1
LT1936
1936fa
APPLICATIO S
U
FEATURES
TYPICAL APPLICATIO
U
DESCRIPTIO
U
1.4A, 500kHz Step-Down
Switching Regulator
Wide Input Range: 3.6V to 36V
Short-Circuit Protected Over Full Input Range
1.9A Guaranteed Minimum Switch Current
5V at 1.4A from 10V to 36V Input
3.3V at 1.4A from 7V to 36V Input
5V at 1.2A from 6.3V to 36V Input
3.3V at 1.2A from 4.5V to 36V Input
Output Adjustable Down to 1.20V
500kHz Fixed Frequency Operation
Soft-Start
Uses Small Ceramic Capacitors
Internal or External Compensation
Low Shutdown Current: <2
A
Thermally Enhanced 8-Lead MSOP Package
Automotive Battery Regulation
Industrial Control Supplies
Unregulated Wall Adapters
3.3V Step-Down Converter
Efficiency
The LT
1936 is a current mode PWM step-down DC/DC
converter with an internal 1.9A power switch, packaged in
a tiny, thermally enhanced 8-lead MSOP. The wide input
range of 3.6V to 36V makes the LT1936 suitable for
regulating power from a wide variety of sources, including
automotive batteries, 24V industrial supplies and unregu-
lated wall adapters. Its high operating frequency allows
the use of small, low cost inductors and ceramic capaci-
tors, resulting in low, predictable output ripple.
Cycle-by-cycle current limit, frequency foldback and ther-
mal shutdown provide protection against shorted outputs,
and soft-start eliminates input current surge during start-
up. Transient response can be optimized by using external
compensation components, or board space can be mini-
mized by using internal compensation. The low current
(<2
A) shutdown mode enables easy power management
in battery-powered systems.
V
IN
4.5V TO 36V
ON OFF
0.22
F
10
H
17.4k
22
F
1936 TA01a
4.7
F
V
OUT
3.3V
1.2A
V
IN
BOOST
V
C
GND
COMP
FB
LT1936
SHDN
SW
10k
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
LOAD CURRENT (A)
0
65
EFFICIENCY (%)
70
75
80
85
95
0.5
1
1936 TA01b
1.5
90
V
OUT
= 5V
V
IN
= 12V
V
OUT
= 3.3V
2
LT1936
1936fa
(Note 1)
V
IN
Voltage ............................................... 0.4V to 36V
BOOST Voltage ........................................................ 43V
BOOST Above SW Voltage ....................................... 20V
SHDN Voltage ........................................... 0.4V to 36V
FB, V
C
, COMP Voltage ............................................... 6V
Operating Temperature Range (Note 2)
LT1936E ............................................. 40
C to 85C
LT1936I ............................................ 40
C to 125C
LT1936H .......................................... 40
C to 150C
Maximum Junction Temperature
LT1936E, LT1936I ............................................ 125
C
LT1936H ......................................................... 150
C
Storage Temperature Range .................. 65
C to 150C
Lead Temperature (Soldering, 10 sec).................. 300
C
JA
= 40
C/W,
JC
= 10
C/W
EXPOSED PAD (PIN 9) IS GND
MUST BE CONNECTED TO PCB
ORDER PART
NUMBER
MS8E PART MARKING
LT1936EMS8E
LT1936IMS8E
LT1936HMS8E
LTBMT
LTBRV
LTBWB
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Undervoltage Lockout
3.45
3.6
V
Quiescent Current
V
FB
= 1.5V
1.8
2.5
mA
Quiescent Current in Shutdown
V
SHDN
= 0V
0.1
2
A
FB Voltage
1.175
1.200
1.215
V
FB Pin Bias Current (Note 4)
V
FB
= 1.20V, E and I Grades
50
200
nA
H Grade
50
300
nA
FB Voltage Line Regulation
V
IN
= 5V to 36V
0.01
%/V
Error Amp g
m
V
C
= 0.5V, I
VC
=
5A
250
S
Error Amp Voltage Gain
V
C
= 0.8V, 1.2V
150
V
C
Clamp
1.8
V
V
C
Switch Threshold
0.7
V
Internal Compensation R
50
k
Internal Compensation C
V
COMP
= 1V
150
pF
COMP Pin Leakage
V
COMP
= 1.8V, E and I Grades
1
A
H Grade
2
A
Switching Frequency
V
FB
= 1.1V
400
500
600
kHz
V
FB
= 0V
40
kHz
Maximum Duty Cycle
87
92
%
Switch Current Limit
1.9
2.2
2.6
A
Switch V
CESAT
I
SW
= 1.2A
410
520
mV
Switch Leakage Current
2
A
Minimum BOOST Voltage Above SW
I
SW
= 1.2A
2
2.2
V
The
denotes specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25
C.
V
IN
= 12V, V
BOOST
= 17V, unless otherwise noted. (Note 2)
ABSOLUTE AXI U RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
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ELECTRICAL CHARACTERISTICS
Consult factory for parts specified with wider operating temperature ranges.
1
2
3
4
BOOST
V
IN
SW
GND
8
7
6
5
COMP
V
C
FB
SHDN
TOP VIEW
9
MS8E PACKAGE
8-LEAD PLASTIC MSOP
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
3
LT1936
1936fa
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
BOOST Pin Current
I
SW
= 1.2A
28
50
mA
BOOST Pin Leakage
V
SW
= 0V
0.1
1
A
SHDN Input Voltage High
2.3
V
SHDN Input Voltage Low
0.3
V
SHDN Pin Current
V
SHDN
= 2.3V (Note 5)
34
50
A
V
SHDN
= 12V
140
240
A
V
SHDN
= 0V
0.01
0.1
A
The
denotes specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25
C.
V
IN
= 12V, V
BOOST
= 17V, unless otherwise noted. (Note 2)
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: The LT1936E is guaranteed to meet performance specifications
from 0
C to 70C. Specifications over the 40C to 85C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LT1936I specifications are
guaranteed over the 40
C to 125C temperature range. The LT1936H
specifications are guaranteed over the 40
C to 150C temperature range.
High junction temperatures degrade operating lifetimes. Operating lifetime
at junction temperatures greater than 125
C is derated to 1000 hours.
Note 3: Current limit guaranteed by design and/or correlation to static test.
Slope compensation reduces current limit at higher duty cycle.
Note 4: Current flows out of pin.
Note 5: Current flows into pin.
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Efficiency, V
OUT
= 5V
Efficiency, V
OUT
= 3.3V
Switch Current Limit
LOAD CURRENT (A)
0
60
EFFICIENCY (%)
70
80
90
100
0.5
1.0
1936 G01
1.5
V
OUT
= 5V
T
A
= 25
C
D1 = DFLS140L
L1 = 15
H, TOKO D63CB
V
IN
= 12V
V
IN
= 24V
LOAD CURRENT (A)
0
60
EFFICIENCY (%)
70
80
90
100
0.5
1.0
1936 G02
1.5
V
OUT
= 3.3V
T
A
= 25
C
D1 = DFLS140L
L1 = 10
H, TOKO D63CB
V
IN
= 5V
V
IN
= 12V
V
IN
= 24V
DUTY CYCLE (%)
0
0
CURRENT LIMIT (A)
0.5
1.0
1.5
2.0
2.5
3.0
20
40
TYP
MIN
60
80
1936 G03
100
4
LT1936
1936fa
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Maximum Load Current
Maximum Load Current
Switch Voltage Drop
Feedback Voltage
Undervoltage Lockout
Switching Frequency
Frequency Foldback
Soft-Start
SHDN Pin Current
INPUT VOLTAGE (V)
0
1.0
LOAD CURRENT (A)
1.2
1.4
1.6
1.8
10
20
5
15
25
1936 G04
30
V
OUT
= 5V
L = 15
H
L = 10
H
INPUT VOLTAGE (V)
0
1.0
LOAD CURRENT (A)
1.2
1.4
1.6
1.8
10
20
5
15
25
1936 G05
30
V
OUT
= 3.3V
L = 6.8
H
L = 10
H
SWITCH CURRENT (A)
0
0
SWITCH VOLTAGE DROP (mV)
100
200
300
400
600
0.5
1.0
1936 G06
1.5
500
T
A
= 45
C
T
A
= 85
C
T
A
= 25
C
TEMPERATURE (
C)
1.185
FEEDBACK VOLTAGE (V)
1.195
1.210
1936 G07
1.190
1.205
1.200
50 25
0
25
50
75
100
150
125
TEMPERATURE (
C)
50
3.0
UVLO (V)
3.2
3.4
3.6
3.8
25
0
25
50
1936 G08
75
100
150
125
TEMPERATURE (
C)
50
400
SWITCHING FREQUENCY (kHz)
450
500
550
600
25
0
25
50
1936 G09
75
100
150
125
FB PIN VOLTAGE (V)
0
700
T
A
= 25
C
600
500
400
300
200
100
0
1936 G10
0.5
1.0
1.5
SWITCHING FREQUENCY (kHz)
SHDN PIN VOLTAGE (V)
0
0
SWITCH CURRENT LIMIT (A)
0.5
1.0
1.5
2.0
2.5
3.0
T
A
= 25
C
DC = 30%
1
2
3
4
1936 G11
SHDN PIN VOLTAGE (V)
0
0
SHDN PIN CURRENT (
A)
50
100
150
200
4
8
1936 G12
12
16
T
A
= 25
C
5
LT1936
1936fa
TYPICAL PERFOR A CE CHARACTERISTICS
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Minimum Input Voltage
Minimum Input Voltage
Switching Waveforms
Switching Waveforms,
Discontinuous Mode
Switch Current Limit
V
C
Voltages
LOAD CURRENT (mA)
1
INPUT VOLTAGE (V)
6
7
1936 G13
5
4
10
100
1000
8
TO START
V
OUT
= 5V
T
A
= 25
C
L = 15
H
TO RUN
LOAD CURRENT (mA)
0
3.0
INPUT VOLTAGE (V)
3.5
4.0
4.5
5.0
5.5
6.0
10
TO START
TO RUN
100
1000
1936 G14
V
OUT
= 3.3V
T
A
= 25
C
L = 10
H
TEMPERATURE (
C)
50
SWITCH CURRENT LIMIT (A)
2.0
2.5
3.0
25
75
1936 G15
1.5
1.0
25
0
50
100
150
125
0.5
0
V
SW
10V/DIV
I
L
500mA/DIV
V
OUT
20mV/DIV
1
s/DIV
V
IN
= 12V
V
OUT
= 3.3V
I
OUT
= 1A
L = 10
H
C
OUT
= 22
F
1936 G16
V
SW
10V/DIV
I
L
500mA/DIV
V
OUT
20mV/DIV
1
s/DIV
V
IN
= 12V
V
OUT
= 3.3V
I
OUT
= 50mA
L = 10
H
C
OUT
= 22
F
1936 G17
TEMPERATURE (
C)
50 25
0
0.5
V
C
VOLTAGE (V)
1.5
0
50
75
1936 G18
1.0
2.5
2.0
25
100
150
125
CURRENT LIMIT CLAMP
SWITCHING THRESHOLD
Error Amp Output Current
FB PIN VOLTAGE (V)
0
60
V
C
PIN CURRENT (
A)
40
20
0
20
60
1
1936 G19
2
40
T
A
= 25
C
V
C
= 0.5V
6
LT1936
1936fa
PI FU CTIO S
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U
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BLOCK DIAGRA
W
BOOST (Pin 1): The BOOST pin is used to provide a drive
voltage, higher than the input voltage, to the internal
bipolar NPN power switch.
V
IN
(Pin 2): The V
IN
pin supplies current to the LT1936's
internal regulator and to the internal power switch. This
pin must be locally bypassed.
SW (Pin 3): The SW pin is the output of the internal power
switch. Connect this pin to the inductor, catch diode and
boost capacitor.
GND (Pin 4): Tie the GND pin to a local ground plane below
the LT1936 and the circuit components. Return the feed-
back divider to this pin.
SHDN (Pin 5): The SHDN pin is used to put the LT1936
in shutdown mode. Tie to ground to shut down the
LT1936. Tie to 2.3V or more for normal operation. If the
shutdown feature is not used, tie this pin to the V
IN
pin.
SHDN also provides a soft-start function; see the Appli-
cations Information. Do not drive SHDN more than 5V
above V
IN
.
FB (Pin 6): The LT1936 regulates its feedback pin to
1.200V. Connect the feedback resistor divider tap to this
pin. Set the output voltage according to V
OUT
= 1.200V
(1 + R1/R2). A good value for R2 is 10k.
V
C
(Pin 7): The V
C
pin is used to compensate the LT1936
control loop by tying an external RC network from this pin
to ground. The COMP pin provides access to an internal
RC network that can be used instead of the external
components.
COMP (Pin 8): To use the internal compensation network,
tie the COMP pin to the V
C
pin. Otherwise, tie COMP to
ground or leave it floating.
Exposed Pad (Pin 9): The Exposed Pad must be soldered
to the PCB and electrically connected to ground. Use a
large ground plane and thermal vias to optimize thermal
performance.
4
R
DRIVER
Q1
S
OSC
SLOPE
COMP
FREQUENCY
FOLDBACK
INT REG
AND
UVLO
V
C
g
m
1.200V
1936 BD
8
2
5
Q
Q
1
3
BOOST
SW
6
FB
GND
R
C
50k
C
C
150pF
V
OUT
R1
R2
L1
D2
C3
C1
D1
V
IN
C2
V
IN
ON OFF
COMP
7
V
C
R4
C5
C4
R3
SHDN
7
LT1936
1936fa
OPERATIO
U
(Refer to Block Diagram)
The LT1936 is a constant frequency, current mode step-
down regulator. A 500kHz oscillator enables an RS flip-
flop, turning on the internal 1.9A power switch Q1. An
amplifier and comparator monitor the current flowing
between the V
IN
and SW pins, turning the switch off when
this current reaches a level determined by the voltage at
V
C
. An error amplifier measures the output voltage through
an external resistor divider tied to the FB pin and servos the
V
C
pin. If the error amplifier's output increases, more
current is delivered to the output; if it decreases, less
current is delivered. An active clamp (not shown) on the V
C
pin provides current limit. The V
C
pin is also clamped to
the voltage on the SHDN pin; soft-start is implemented by
generating a voltage ramp at the SHDN pin using an
external resistor and capacitor.
An internal regulator provides power to the control cir-
cuitry. This regulator includes an undervoltage lockout to
prevent switching when V
IN
is less than ~3.45V. The
SHDN pin is used to place the LT1936 in shutdown,
disconnecting the output and reducing the input current to
less than 2
A.
The switch driver operates from either the input or from
the BOOST pin. An external capacitor and diode are used
to generate a voltage at the BOOST pin that is higher than
the input supply. This allows the driver to fully saturate the
internal bipolar NPN power switch for efficient operation.
The oscillator reduces the LT1936's operating frequency
when the voltage at the FB pin is low. This frequency
foldback helps to control the output current during startup
and overload.
8
LT1936
1936fa
APPLICATIO S I FOR ATIO
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FB Resistor Network
The output voltage is programmed with a resistor divider
between the output and the FB pin. Choose the 1%
resistors according to:
R
R
V
OUT
1
2
1 200
1
=
.
R2 should be 20k or less to avoid bias current errors.
Reference designators refer to the Block Diagram.
Input Voltage Range
The input voltage range for LT1936 applications depends
on the output voltage and the Absolute Maximum Ratings
of the V
IN
and BOOST pins.
The minimum input voltage is determined by either the
LT1936's minimum operating voltage of ~3.45V or by its
maximum duty cycle. The duty cycle is the fraction of time
that the internal switch is on and is determined by the input
and output voltages:
DC
V
V
V
V
V
OUT
D
IN
SW
D
=
+
+
where V
D
is the forward voltage drop of the catch diode
(~0.5V) and V
SW
is the voltage drop of the internal switch
(~0.5V at maximum load). This leads to a minimum input
voltage of:
V
V
V
DC
V
V
IN MIN
OUT
D
MAX
D
SW
(
)
=
+
+
with DC
MAX
= 0.87.
The maximum input voltage is determined by the absolute
maximum ratings of the V
IN
and BOOST pins and by the
minimum duty cycle DC
MIN
= 0.08:
V
V
V
DC
V
V
IN MAX
OUT
D
MIN
D
SW
(
)
=
+
+
Note that this is a restriction on the operating input
voltage; the circuit will tolerate transient inputs up to the
absolute maximum ratings of the V
IN
and BOOST pins.
Inductor Selection and Maximum Output Current
A good first choice for the inductor value is
L = 2.2 (V
OUT
+ V
D
)
where V
D
is the voltage drop of the catch diode (~0.4V) and
L is in
H. With this value the maximum output current will
be above 1.2A at all duty cycles and greater than 1.4A for
duty cycles less than 50% (V
IN
> 2 V
OUT
). The inductor's
RMS current rating must be greater than the maximum
load current and its saturation current should be about
30% higher. For robust operation in fault conditions
(start-up or short circuit) and high input voltage (>30V),
the saturation current should be above 2.6A. To keep the
efficiency high, the series resistance (DCR) should be less
than 0.1
, and the core material should be intended for
high frequency applications. Table 1 lists several vendors
and suitable types.
Table 1. Inductor Vendors
VENDOR
URL
PART SERIES
TYPE
Murata
www.murata.com
LQH55D
Open
TDK
www.component.tdk.com
SLF7045
Shielded
SLF10145
Shielded
Toko
www.toko.com
D62CB
Shielded
D63CB
Shielded
D75C
Shielded
D75F
Open
Sumida
www.sumida.com
CR54
Open
CDRH74
Shielded
CDRH6D38
Shielded
CR75
Open
Of course, such a simple design guide will not always re-
sult in the optimum inductor for your application. A larger
value provides a slightly higher maximum load current and
will reduce the output voltage ripple. If your load is lower
than 1.2A, then you can decrease the value of the inductor
and operate with higher ripple current. This allows you to
use a physically smaller inductor, or one with a lower DCR
resulting in higher efficiency. Be aware that if the inductance
differs from the simple rule above, then the maximum load
current will depend on input voltage. There are several
graphs in the Typical Performance Characteristics section
9
LT1936
1936fa
APPLICATIO S I FOR ATIO
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of this data sheet that show the maximum load current as
a function of input voltage and inductor value for several
popular output voltages. Low inductance may result in
discontinuous mode operation, which is okay but further
reduces maximum load current. For details of maximum
output current and discontinuous mode operation, see
Linear Technology Application Note 44. Finally, for duty
cycles greater than 50% (V
OUT
/V
IN
> 0.5), there is a mini-
mum inductance required to avoid subharmonic oscilla-
tions. Choosing L greater than 1.6 (V
OUT
+ V
D
)
H prevents
subharmonic oscillations at all duty cycles.
Catch Diode
A 1A Schottky diode is recommended for the catch diode,
D1. The diode must have a reverse voltage rating equal to
or greater than the maximum input voltage. The ON
Semiconductor MBRM140 is a good choice. It is rated for
1A DC at a case temperature of 110
C and 1.5A at a case
temperature of 95
C. Diode Incorporated's DFLS140L is
rated for 1.1A average current; the DFLS240L is rated for
2A average current. The average diode current in an
LT1936 application is approximately I
OUT
(1 DC).
Input Capacitor
Bypass the input of the LT1936 circuit with a 4.7
F or
higher value ceramic capacitor of X7R or X5R type. Y5V
types have poor performance over temperature and ap-
plied voltage, and should not be used. A 4.7
F ceramic is
adequate to bypass the LT1936 and will easily handle the
ripple current. However, if the input power source has high
impedance, or there is significant inductance due to long
wires or cables, additional bulk capacitance may be nec-
essary. This can be provided with a low performance
electrolytic capacitor.
Step-down regulators draw current from the input supply
in pulses with very fast rise and fall times. The input
capacitor is required to reduce the resulting voltage ripple
at the LT1936 and to force this very high frequency
switching current into a tight local loop, minimizing EMI.
A 4.7
F capacitor is capable of this task, but only if it is
placed close to the LT1936 and the catch diode; see the
PCB Layout section. A second precaution regarding the
ceramic input capacitor concerns the maximum input
voltage rating of the LT1936. A ceramic input capacitor
combined with trace or cable inductance forms a high
quality (under damped) tank circuit. If the LT1936 circuit
is plugged into a live supply, the input voltage can ring to
twice its nominal value, possibly exceeding the LT1936's
voltage rating. This situation is easily avoided; see the Hot
Plugging Safety section.
For space sensitive applications, a 2.2
F ceramic capaci-
tor can be used for local bypassing of the LT1936 input.
However, the lower input capacitance will result in in-
creased input current ripple and input voltage ripple, and
may couple noise into other circuitry. Also, the increased
voltage ripple will raise the minimum operating voltage of
the LT1936 to ~3.7V.
Output Capacitor
The output capacitor has two essential functions. Along
with the inductor, it filters the square wave generated by
the LT1936 to produce the DC output. In this role it
determines the output ripple, and low impedance at the
switching frequency is important. The second function is
to store energy in order to satisfy transient loads and
stabilize the LT1936's control loop.
Ceramic capacitors have very low equivalent series resis-
tance (ESR) and provide the best ripple performance. A
good value is:
C
V
OUT
OUT
=
150
where C
OUT
is in
F. Use X5R or X7R types. This choice will
provide low output ripple and good transient response.
Transient performance can be improved with a high value
capacitor if the compensation network is also adjusted to
maintain the loop bandwidth.
A lower value of output capacitor can be used, but tran-
sient performance will suffer. With an external compensa-
tion network, the loop gain can be lowered to compensate
for the lower capacitor value. When using the internal
compensation network, the lowest value for stable opera-
tion is:
C
V
OUT
OUT
>
66
10
LT1936
1936fa
APPLICATIO S I FOR ATIO
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This is the minimum output capacitance required, not the
nominal capacitor value. For example, a 3.3V output
requires 20
F of output capacitance. If a small 22F, 6.3V
ceramic capacitor is used, the circuit may be unstable
because the effective capacitance is lower than the nomi-
nal capacitance when biased at 3.3V. Look carefully at the
capacitor's data sheet to find out what the actual capaci-
tance is under operating conditions (applied voltage and
temperature). A physically larger capacitor, or one with a
higher voltage rating, may be required.
High performance electrolytic capacitors can be used for
the output capacitor. Low ESR is important, so choose one
that is intended for use in switching regulators. The ESR
should be specified by the supplier, and should be 0.05
or less. Such a capacitor will be larger than a ceramic
capacitor and will have a larger capacitance, because the
capacitor must be large to achieve low ESR. Table 2 lists
several capacitor vendors.
Frequency Compensation
The LT1936 uses current mode control to regulate the
output. This simplifies loop compensation. In particular,
the LT1936 does not require the ESR of the output capaci-
tor for stability, so you are free to use ceramic capacitors
to achieve low output ripple and small circuit size.
Frequency compensation is provided by the components
tied to the V
C
pin, as shown in Figure 1. Generally a
capacitor (C
C
) and a resistor (R
C
) in series to ground are
used. In addition, there may be lower value capacitor in
parallel. This capacitor (C
F
) is not part of the loop compen-
sation but is used to filter noise at the switching frequency,
and is required only if a phase-lead capacitor is used or if
the output capacitor has high ESR. An alternative to using
external compensation components is to use the internal
RC network by tying the COMP pin to the V
C
pin. This
reduces component count but does not provide the opti-
mum transient response when the output capacitor value
is high, and the circuit may not be stable when the output
capacitor value is low. If the internal compensation net-
work is not used, tie COMP to ground or leave it floating.
Loop compensation determines the stability and transient
performance. Designing the compensation network is a
Table 2. Capacitor Vendors
Vendor
Phone
URL
Part Series
Comments
Panasonic
(714) 373-7366
www.panasonic.com
Ceramic,
Polymer,
EEF Series
Tantalum
Kemet
(864) 963-6300
www.kemet.com
Ceramic,
Tantalum
T494, T495
Sanyo
(408) 749-9714
www.sanyovideo.com
Ceramic,
Polymer,
POSCAP
Tantalum
Murata
(404) 436-1300
www.murata.com
Ceramic
AVX
www.avxcorp.com
Ceramic,
Tantalum
TPS Series
Taiyo Yuden
(864) 963-6300
www.taiyo-yuden.com
Ceramic
+
1.25V
SW
V
C
COMP
GND
50k
600k
150pF
LT1936
1936 F01
R1
OUTPUT
ESR
C
F
C
C
R
C
ERROR
AMPLIFIER
FB
R2
C1
C1
CURRENT MODE
POWER STAGE
g
m
= 2mho
g
m
=
250
mho
+
POLYMER
OR
TANTALUM
CERAMIC
C
PL
Figure 1. Model for Loop Response
11
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APPLICATIO S I FOR ATIO
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Figure 2. Transient Load Response of the LT1936 with Different Output
Capacitors as the Load Current is Stepped from 200mA to 800mA. V
OUT
= 3.3V
bit complicated and the best values depend on the appli-
cation and in particular the type of output capacitor. A
practical approach is to start with one of the circuits in this
data sheet that is similar to your application and tune the
compensation network to optimize the performance. Sta-
bility should then be checked across all operating condi-
tions, including load current, input voltage and temperature.
The LT1375 data sheet contains a more thorough discus-
sion of loop compensation and describes how to test the
stability using a transient load.
Figure 1 shows an equivalent circuit for the LT1936 control
loop. The error amplifier is a transconductance amplifier
with finite output impedance. The power section, consist-
ing of the modulator, power switch and inductor, is
modeled as a transconductance amplifier generating an
output current proportional to the voltage at the V
C
pin.
Note that the output capacitor integrates this current, and
that the capacitor on the V
C
pin (C
C
) integrates the error
amplifier output current, resulting in two poles in the loop.
In most cases a zero is required and comes from either the
output capacitor ESR or from a resistor R
C
in series with
C
C
. This simple model works well as long as the value of
the inductor is not too high and the loop crossover
frequency is much lower than the switching frequency. A
phase lead capacitor (C
PL
) across the feedback divider
may improve the transient response.
Figure 2 compares the transient response across several
output capacitor choices and compensation schemes. In
each case the load current is stepped from 200mA to
800mA and back to 200mA.
COMP
C
OUT
= 22
F
(AVX 1210ZD226MAT)
(2a)
(2b)
(2c)
(2d)
V
OUT
100mV/DIV
V
OUT
100mV/DIV
V
OUT
100mV/DIV
V
OUT
100mV/DIV
I
OUT
500mA/DIV
800mA
200mA
50
s/DIV
1936 F02
V
C
COMP
C
OUT
= 22
F 2
V
C
COMP
C
OUT
= 150
F
(4TPC150M)
V
C
COMP
220k
100pF
C
OUT
= 150
F
(4TPC150M)
V
C
12
LT1936
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APPLICATIO S I FOR ATIO
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BOOST Pin Considerations
Capacitor C3 and diode D2 are used to generate a boost
voltage that is higher than the input voltage. In most cases
a 0.22
F capacitor and fast switching diode (such as the
1N4148 or 1N914) will work well. Figure 3 shows two
ways to arrange the boost circuit. The BOOST pin must be
at least 2.3V above the SW pin for best efficiency. For
outputs of 3V and above, the standard circuit (Figure 3a)
is best. For outputs between 2.8V and 3V, use a 0.47
F
capacitor and a Schottky diode. For lower output voltages
the boost diode can be tied to the input (Figure 3b), or to
another supply greater than 2.8V. The circuit in Figure 3a
is more efficient because the BOOST pin current comes
from a lower voltage. You must also be sure that the
maximum voltage rating of the BOOST pin is not exceeded.
A 2.5V output presents a special case. This is a popular
output voltage, and the advantage of connecting the boost
circuit to the output is that the circuit will accept a 36V
maximum input voltage rather than 20V (due to the
BOOST pin rating). However, 2.5V is marginally adequate
to support the boosted drive stage at low ambient tem-
peratures. Therefore, special care and some restrictions
on operation are necessary when powering the BOOST pin
from a 2.5V output. Minimize the voltage loss in the boost
circuit by using a 1
F boost capacitor and a good, low drop
Schottky diode (such as the ON Semi MBR0540). Because
the required boost voltage increases at low temperatures,
the circuit will supply only 1A of output current when the
ambient temperature is 45
C, increasing to 1.2A at 0C.
Also, the minimum input voltage to start the boost circuit
is higher at low temperature. See the Typical Applications
section for a 2.5V schematic and performance curves.
The minimum operating voltage of an LT1936 application
is limited by the undervoltage lockout (~3.45V) and by the
maximum duty cycle as outlined above. For proper start-
up, the minimum input voltage is also limited by the boost
circuit. If the input voltage is ramped slowly, or the LT1936
is turned on with its SHDN pin when the output is already
in regulation, then the boost capacitor may not be fully
charged. Because the boost capacitor is charged with the
energy stored in the inductor, the circuit will rely on some
minimum load current to get the boost circuit running
properly. This minimum load will depend on input and
output voltages, and on the arrangement of the boost
circuit. The minimum load generally goes to zero once the
circuit has started. Figure 4 shows a plot of minimum load
to start and to run as a function of input voltage. In many
cases the discharged output capacitor will present a load
to the switcher, which will allow it to start. The plots show
the worst-case situation where V
IN
is ramping very slowly.
For lower start-up voltage, the boost diode can be tied to
V
IN
; however, this restricts the input range to one-half of
the absolute maximum rating of the BOOST pin.
At light loads, the inductor current becomes discontinu-
ous and the effective duty cycle can be very high. This
reduces the minimum input voltage to approximately
300mV above V
OUT
. At higher load currents, the inductor
current is continuous and the duty cycle is limited by the
maximum duty cycle of the LT1936, requiring a higher
input voltage to maintain regulation.
Soft-Start
The SHDN pin can be used to soft-start the LT1936,
reducing the maximum input current during start-up. The
SHDN pin is driven through an external RC filter to create
a voltage ramp at this pin. Figure 5 shows the start-up
waveforms with and without the soft-start circuit. By
choosing a large RC time constant, the peak start-up
Figure 3. Two Circuits for Generating the Boost Voltage
V
IN
BOOST
GND
SW
V
IN
LT1936
(3a)
D2
V
OUT
C3
V
BOOST
V
SW
V
OUT
MAX V
BOOST
V
IN
+ V
OUT
V
IN
BOOST
GND
SW
V
IN
LT1936
(3b)
D2
1933 F03
V
OUT
C3
V
BOOST
V
SW
V
IN
MAX V
BOOST
2V
IN
13
LT1936
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APPLICATIO S I FOR ATIO
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Figure 5. To Soft-Start the LT1936, Add a Resistor and Capacitor to the SHDN Pin.
V
IN
= 12V, V
OUT
= 3.3V, C
OUT
= 2
22F, R
LOAD
= 3.3
Figure 4. The Minimum Input Voltage Depends on Output Voltage, Load Current and Boost Circuit
Minimum Input Voltage V
OUT
= 3.3V
Minimum Input Voltage V
OUT
= 5V
RUN
RUN
5V/DIV
I
IN
500mA/DIV
50
s/DIV
V
OUT
5V/DIV
RUN
5V/DIV
I
IN
500mA/DIV
V
OUT
5V/DIV
SHDN
GND
1936 F05a
0.5ms/DIV
1936 F05b
RUN
15k
0.22
F
SHDN
GND
LOAD CURRENT (mA)
0
3.0
INPUT VOLTAGE (V)
3.5
4.0
4.5
5.0
5.5
6.0
10
TO START
TO RUN
100
1000
1936 G14
V
OUT
= 3.3V
T
A
= 25
C
L = 10
H
LOAD CURRENT (mA)
1
INPUT VOLTAGE (V)
6
7
1936 G13
5
4
10
100
1000
8
TO START
V
OUT
= 5V
T
A
= 25
C
L = 15
H
TO RUN
current can be reduced to the current that is required to
regulate the output, with no overshoot. Choose the value
of the resistor so that it can supply 60
A when the SHDN
pin reaches 2.3V.
Shorted and Reversed Input Protection
If the inductor is chosen so that it won't saturate exces-
sively, an LT1936 buck regulator will tolerate a shorted
output. There is another situation to consider in systems
where the output will be held high when the input to the
LT1936 is absent. This may occur in battery charging
applications or in battery backup systems where a battery
or some other supply is diode OR-ed with the LT1936's
output. If the V
IN
pin is allowed to float and the SHDN pin
is held high (either by a logic signal or because it is tied to
V
IN
), then the LT1936's internal circuitry will pull its
quiescent current through its SW pin. This is fine if your
system can tolerate a few mA in this state. If you ground
14
LT1936
1936fa
APPLICATIO S I FOR ATIO
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V
IN
BOOST
COMP GND FB
SHDN
V
C
SW
D4
MBRS140
V
IN
LT1936
1936 F06
V
OUT
BACKUP
Figure 6. Diode D4 Prevents a Shorted Input from Discharging
a Backup Battery Tied to the Output; It Also Protects the Circuit
from a Reversed Input. The LT1936 Runs Only When the Input
is Present
Figure 7. A Good PCB Layout Ensures Low EMI Operation
the SHDN pin, the SW pin current will drop to essentially
zero. However, if the V
IN
pin is grounded while the output
is held high, then parasitic diodes inside the LT1936 can
pull large currents from the output through the SW pin and
the V
IN
pin. Figure 6 shows a circuit that will run only when
the input voltage is present and that protects against a
shorted or reversed input.
High Temperature Considerations
The die temperature of the LT1936 must be lower than the
maximum rating of 125
C (150C for the H grade). This is
generally not a concern unless the ambient temperature is
above 85
C. For higher temperatures, care should be
taken in the layout of the circuit to ensure good heat
sinking of the LT1936. The maximum load current should
be derated as the ambient temperature approaches 125
C
(150
C for the H grade).
The die temperature is calculated by multiplying the LT1936
power dissipation by the thermal resistance from junction
to ambient. Power dissipation within the LT1936 can be
estimated by calculating the total power loss from an
efficiency measurement and subtracting the catch diode
loss. The resulting temperature rise at full load is nearly
independent of input voltage. Thermal resistance depends
on the layout of the circuit board, but values from 40
C/W
to 60
C/W are typical.
Die temperature rise was measured on a 4-layer, 5cm
6.5cm circuit board in still air at a load current of 1.4A. For
12V input to 3.3V output the die temperature elevation
above ambient was 26
C; for 24V in to 3.3V out the rise
was 31
C; for 12V in to 5V the rise was 31C and for 24V
in to 5V the rise was 34
C.
D1
R2
R4
C2
C3
D2
MINIMIZE
LT1936
C2, D1 LOOP
IN
GND
R1
C1
L1
GND
VIAS
OUT
1936 F07
PCB Layout
For proper operation and minimum EMI, care must be
taken during printed circuit board layout. Figure 7 shows
the recommended component placement with trace, ground
plane and via locations. Note that large, switched currents
flow in the LT1936's V
IN
and SW pins, the catch diode (D1)
and the input capacitor (C2). The loop formed by these
components should be as small as possible. These com-
ponents, along with the inductor and output capacitor,
should be placed on the same side of the circuit board, and
their connections should be made on that layer. Place a
local, unbroken ground plane below these components.
The SW and BOOST nodes should be as small as possible.
Finally, keep the FB and V
C
nodes small so that the ground
traces will shield them from the SW and BOOST nodes.
The Exposed Pad on the bottom of the package must be
soldered to ground so that the pad acts as a heat sink. To
keep thermal resistance low, extend the ground plane as
much as possible, and add thermal vias under and near the
LT1936 to additional ground planes within the circuit
board and on the bottom side.
15
LT1936
1936fa
APPLICATIO S I FOR ATIO
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Hot Plugging Safely
The small size, robustness and low impedance of ceramic
capacitors make them an attractive option for the input
bypass capacitor of LT1936 circuits. However, these ca-
pacitors can cause problems if the LT1936 is plugged into
a live supply (see Linear Technology Application Note 88
for a complete discussion). The low loss ceramic capaci-
tor combined with stray inductance in series with the
power source forms an under damped tank circuit, and the
voltage at the V
IN
pin of the LT1936 can ring to twice the
+
+
LT1936
4.7
F
V
IN
20V/DIV
I
IN
10A/DIV
20
s/DIV
V
IN
CLOSING SWITCH
SIMULATES HOT PLUG
I
IN
(8a)
(8b)
(8c)
LOW
IMPEDANCE
ENERGIZED
24V SUPPLY
STRAY
INDUCTANCE
DUE TO 6 FEET
(2 METERS) OF
TWISTED PAIR
+
+
LT1936
4.7
F
22
F
35V
AI.EI.
LT1936
4.7
F
0.1
F
0.7
1936 F08
V
IN
20V/DIV
I
IN
10A/DIV
20
s/DIV
V
IN
20V/DIV
I
IN
10A/DIV
20
s/DIV
DANGER
RINGING V
IN
MAY EXCEED
ABSOLUTE MAXIMUM
RATING OF THE LT1936
Figure 8. A Well Chosen Input Network Prevents Input Voltage Overshoot and
Ensures Reliable Operation When the LT1936 is Connected to a Live Supply
nominal input voltage, possibly exceeding the LT1936's
rating and damaging the part. If the input supply is poorly
controlled or the user will be plugging the LT1936 into an
energized supply, the input network should be designed to
prevent this overshoot.
Figure 8 shows the waveforms that result when an LT1936
circuit is connected to a 24V supply through six feet of
24-gauge twisted pair. The first plot is the response with
a 4.7
F ceramic capacitor at the input. The input voltage
rings as high as 50V and the input current peaks at 26A. One
16
LT1936
1936fa
TYPICAL APPLICATIO S
U
V
IN
4.5V TO 36V
ON OFF
D1
D2
L1
10
H
R1
17.4k
C2
47
F
1936 TA03
C1
4.7
F
C3
0.22
F
V
OUT
3.3V
1.2A
V
IN
BOOST
V
C
GND
COMP
FB
LT1936
SHDN
SW
R2
10k
3.3V Step-Down Converter
5V Step-Down Converter
V
IN
6.3V TO 36V
ON OFF
D1
D2
L1
15
H
R1
31.6k
C2
22
F
1936 TA04
C1
4.7
F
C3
0.22
F
V
OUT
5V
1.2A
V
IN
BOOST
V
C
GND
COMP
FB
LT1936
SHDN
SW
R2
10k
APPLICATIO S I FOR ATIO
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method of damping the tank circuit is to add another ca-
pacitor with a series resistor to the circuit. In Figure 8b an
aluminum electrolytic capacitor has been added. This
capacitor's high equivalent series resistance damps the
circuit and eliminates the voltage overshoot. The extra
capacitor improves low frequency ripple filtering and can
slightly improve the efficiency of the circuit, though it is likely
to be the largest component in the circuit. An alternative
solution is shown in Figure 8c. A 0.7
resistor is added in
series with the input to eliminate the voltage overshoot (it
also reduces the peak input current). A 0.1
F capacitor
improves high frequency filtering. This solution is smaller
and less expensive than the electrolytic capacitor. For high
input voltages its impact on efficiency is minor, reducing
efficiency by one percent for a 5V output at full load oper-
ating from 24V.
Other Linear Technology Publications
Application Notes 19, 35 and 44 contain more detailed
descriptions and design information for buck regulators
and other switching regulators. The LT1376 data sheet
has a more extensive discussion of output ripple, loop
compensation and stability testing. Design Note 100 shows
how to generate a bipolar output supply using a buck
regulator.
17
LT1936
1936fa
1.8V Step-Down Converter
TYPICAL APPLICATIO S
U
V
IN
3.6V TO 20V
ON OFF
D1
D2
L1
4.7
H
R1
10k
D1: DFLS140L
D2: 1N4148
L1: TOKO D63CB
C2
47
F
2
1936 TA05a
C1
4.7
F
C3
0.22
F
V
OUT
1.8V
1.3A
V
IN
BOOST
V
C
GND
COMP
FB
LT1936
SHDN
SW
R2
20k
1.2V Step-Down Converter
LOAD CURRENT (A)
0
50
EFFICIENCY (%)
POWER LOSS (W)
60
70
80
90
0
0.5
1.0
1.5
2.0
0.5
1
1936 TA05b
1.5
POWER LOSS
V
IN
= 5V
V
IN
= 12V
V
OUT
= 1.8V
T
A
= 25
C
Efficiency, 1.8V Output
V
IN
3.6V TO 20V
ON OFF
D1
D2
L1
3.3
H
D1: DFLS140L
D2: 1N4148
L1: TOKO D63CB
C2
47
F
2
1936 TA06a
C1
4.7
F
C3
0.22
F
V
OUT
1.2V
1.3A
V
IN
BOOST
V
C
GND
COMP
FB
LT1936
SHDN
SW
100k
Efficiency, 1.2V Output
LOAD CURRENT (A)
0
50
55
EFFICIENCY (%)
POWER LOSS (W)
60
65
70
75
80
0
0.5
1.0
1.5
2.0
0.5
1
1936 TA06b
1.5
POWER LOSS
V
IN
= 5V
V
IN
= 12V
V
OUT
= 1.2V
T
A
= 25
C
18
LT1936
1936fa
TYPICAL APPLICATIO S
U
2.5V Step-Down Converter
V
IN
3.6V TO 36V
ON OFF
D1
D2
L1
6.2
H
R1
11k
D1: DFLS140L
D2: MBRO540
L1: TOKO D63CB
C2
47
F
1936 TA07a
C1
4.7
F
C3
1
F
V
OUT
2.5V
1.2A
T
A
> 0
C
V
IN
BOOST
V
C
GND
COMP
FB
LT1936
SHDN
SW
R2
10k
Efficiency, 2.5V Output
LOAD CURRENT (A)
0
60
EFFICIENCY (%)
70
80
90
100
0.5
1.0
1936 TA07b
1.5
V
OUT
= 2.5V
T
A
= 25
C
V
IN
= 12V
V
IN
= 5V
Minimum Input Voltage
LOAD CURRENT (mA)
1
INPUT VOLTAGE (V)
4.5
5.0
1936 TA07c
4.0
3.5
3.0
10
100
1000
5.5
V
OUT
= 2.5V
TO START
T
A
= 45
C
TO RUN
T
A
= 45
C
TO START
T
A
= 25
C
TO RUN
T
A
= 25
C
19
LT1936
1936fa
PACKAGE DESCRIPTIO
N
U
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
MS8E Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1662)
MSOP (MS8E) 0603
0.53
0.152
(.021
.006)
SEATING
PLANE
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
0.18
(.007)
0.254
(.010)
1.10
(.043)
MAX
0.22 0.38
(.009 .015)
TYP
0.127
0.076
(.005
.003)
0.86
(.034)
REF
0.65
(.0256)
BSC
0
6 TYP
DETAIL "A"
DETAIL "A"
GAUGE PLANE
1
2
3
4
4.90
0.152
(.193
.006)
8
8
1
BOTTOM VIEW OF
EXPOSED PAD OPTION
7 6 5
3.00
0.102
(.118
.004)
(NOTE 3)
3.00
0.102
(.118
.004)
(NOTE 4)
0.52
(.0205)
REF
1.83
0.102
(.072
.004)
2.06
0.102
(.081
.004)
5.23
(.206)
MIN
3.20 3.45
(.126 .136)
2.083
0.102
(.082
.004)
2.794
0.102
(.110
.004)
0.889
0.127
(.035
.005)
RECOMMENDED SOLDER PAD LAYOUT
0.42
0.038
(.0165
.0015)
TYP
0.65
(.0256)
BSC
20
LT1936
1936fa
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
FAX: (408) 434-0507
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2005
LT/LT 0705 REV A PRINTED IN USA
TYPICAL APPLICATIO
U
2.5V Step-Down Converter
V
IN
3.6V TO 20V
ON OFF
D1
D2
L1
8.2
H
D1: DFLS140L
D2: 1N4148
L1: TOKO D63CB
C2
47
F
1936 TA08a
C1
4.7
F
C3
0.22
F
V
OUT
2.5V
1.3A
V
IN
BOOST
V
C
GND
COMP
FB
LT1936
SHDN
SW
R2
10k
R1
11k
Minimum Input Voltage
LOAD CURRENT (mA)
1
INPUT VOLTAGE (V)
4.5
5.0
1936 TA08b
4.0
3.5
3.0
10
100
1000
5.5
V
OUT
= 2.5V
CONNECTING THE BOOST CIRCUIT TO THE
INPUT LOWERS THE MINIMUM INPUT
VOLTAGE TO RUN AND TO START TO LESS
THAN 3.7V AT ALL LOADS
PART NUMBER
DESCRIPTION
COMMENTS
LT1676
60V, 440mA (I
OUT
), 100kHz, High Efficiency Step-Down
V
IN
: 7.4V to 60V, V
OUT(MIN)
= 1.24V, I
Q
= 3.2mA, I
SD
= 2.5
A,
DC/DC Converter
SO-8 Package
LT1765
25V, 2.75A (I
OUT
), 1.25MHz, High Efficiency Step-Down
V
IN
: 3V to 25V, V
OUT(MIN)
= 1.20V, I
Q
= 1mA, I
SD
= 15
A,
DC/DC Converter
SO-8 and 16-Lead TSSOPE Packages
LT1766
60V, 1.2A (I
OUT
), 200kHz, High Efficiency Step-Down
V
IN
: 5.5V to 60V, V
OUT(MIN)
= 1.20V, I
Q
= 2.5mA, I
SD
= 25
A,
DC/DC Converter
16-Lead TSSOP/TSSOPE Packages
LT1767
25V, 1.2A (I
OUT
), 1.25MHz, High Efficiency Step-Down
V
IN
: 3V to 25V, V
OUT(MIN)
= 1.20V, I
Q
= 1mA, I
SD
= 6
A,
DC/DC Converter
MS8/MS8E Packages
LT1776
40V, 550mA (I
OUT
), 200kHz, High Efficiency Step-Down
V
IN
: 7.4V to 40V, V
OUT(MIN)
= 1.24V, I
Q
= 3.2mA, I
SD
= 30
A,
DC/DC Converter
N8/SO-8 Packages
LT1933
600mA, 500kHz, Step-Down Switching Regulator in SOT-23
V
IN
: 3.6V to 36V, V
OUT(MIN)
= 1.25V, I
Q
= 1.6mA, I
SD
< 1
A,
ThinSOT
TM
Package
LT1940
25V, Dual 1.4A (I
OUT
), 1.1MHz, High Efficiency Step-Down
V
IN
: 3V to 25V, V
OUT(MIN)
= 1.2V, I
Q
= 3.8mA, I
SD
< 1
A,
DC/DC Converter
16-Lead TSSOPE Package
LT1956
60V, 1.2A (I
OUT
), 500kHz, High Efficiency Step-Down
V
IN
: 5.5V to 60V, V
OUT(MIN)
= 1.20V, I
Q
= 2.5mA, I
SD
= 25
A,
DC/DC Converter
16-Lead TSSOP/TSSOPE Packages
LT1976
60V, 1.2A (I
OUT
), 200kHz, High Efficiency Step-Down
V
IN
: 3.3V to 60V, V
OUT(MIN)
= 1.20V, I
Q
= 100
A, I
SD
< 1
A,
DC/DC Converter with Burst Mode
Operation
16-Lead TSSOPE Package
LT3010
80V, 50mA, Low Noise Linear Regulator
V
IN
: 1.5V to 80V, V
OUT(MIN)
= 1.28V, I
Q
= 30
A, I
SD
< 1
A,
MS8E Package
LTC
3407
Dual 600mA (I
OUT
), 1.5MHz, Synchronous Step-Down
V
IN
: 2.5V to 5.5V, V
OUT(MIN)
= 0.6V, I
Q
= 40
A, I
SD
< 1
A,
DC/DC Converter
10-Lead MSE Package
LTC3412
2.5A (I
OUT
), 4MHz, Synchronous Step-Down
V
IN
: 2.5V to 5.5V, V
OUT(MIN)
= 0.8V, I
Q
= 60
A, I
SD
< 1
A,
DC/DC Converter
16-Lead TSSOPE Package
LTC3414
4A (I
OUT
), 4MHz, Synchronous Step-Down
V
IN
: 2.3V to 5.5V, V
OUT(MIN)
= 0.8V, I
Q
= 64
A, I
SD
< 1
A,
DC/DC Converter
20-Lead TSSOPE Package
LT3430/LT3431
60V, 2.75A (I
OUT
), 200kHz/500kHz, High Efficiency
V
IN
: 5.5V to 60V, V
OUT(MIN)
= 1.20V, I
Q
= 2.5mA, I
SD
= 30
A,
Step-Down DC/DC Converters
16-Lead TSSOPE Package
Burst Mode is a registered trademark of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation.
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