1
LT1316
Micropower
DC/DC Converter
with Programmable
Peak Current Limit
s
Precise Control of Peak Switch Current
s
Quiescent Current:
33
A in Active Mode
3
A in Shutdown Mode
s
Low-Battery Detector Active in Shutdown
s
Low Switch V
CESAT
: 300mV at 500mA
s
8-Lead MSOP and SO Packages
s
Operates with V
IN
as Low as 1.5V
s
Logic Level Shutdown Pin
FEATURES
DESCRIPTIO
N
U
The LT
1316 is a micropower step-up DC/DC converter
that operates from an input voltage as low as 1.5V. A
programmable input current limiting function allows pre-
cise control of peak switch current. Peak switch current
can be set to any value between 30mA and 500mA by
adjusting one resistor. This is particularly useful for
DC/DC converters operating from high source impedance
inputs such as lithium coin cells or telephone lines.
The fixed off-time, variable on-time regulation scheme
results in quiescent current of only 33
A in active mode.
Quiescent current decreases to 3
A in shutdown with the
low-battery detector still active.
The LT1316 is available in 8-lead MSOP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
N
U
APPLICATIO
N
S
U
s
Battery Backup
s
LCD Bias
s
Low Power 48V to 5V/3.3V Converters
2-Cell to 5V Step-Up Converter
V
IN
SW
R
SET
GND
FB
SHDN
6
5
8
1
4
3
2
7
LBO
LBI
LT1316
C2
47
F
NC
NC
R5
10k
1%
C1
47
F
2 CELLS
L1
47
H
D1
5V
50mA
D1: MOTOROLA MBR0520L
L1: SUMIDA CD43-470
1316 TA01
+
+
R1
1M
1%
R2
324k
1%
LOAD CURRENT (mA)
0.1
60
EFFICIENCY (%)
80
90
1
10
100
1316 TA02
70
3.3V
IN
2.5V
IN
1.8V
IN
Efficiency vs Load Current
2
LT1316
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
V
IN
Voltage .............................................................. 12V
SW Voltage ............................................... 0.4V to 30V
FB Voltage ..................................................... V
IN
+ 0.3V
R
SET
Voltage ............................................................. 5V
SHDN Voltage ............................................................ 6V
LBI Voltage ................................................................V
IN
LBO Voltage ............................................................. 12V
Maximum Switch Current ................................... 750mA
Maximum Junction Temperature ......................... 125
C
Operating Temperature Range
Commercial ............................................. 0
C to 70
C
Extended Commercial (Note 1) .......... 40
C to 85
C
Industrial (Note 2) .............................. 40
C to 85
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
LT1316CMS8
ORDER PART
NUMBER
MS8 PART MARKING
LTCD
ORDER PART
NUMBER
S8 PART MARKING
1
2
3
4
8
7
6
5
TOP VIEW
LBO
LBI
R
SET
GND
FB
SHDN
V
IN
SW
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125
C,
JA
= 120
C/W
1
2
3
4
LBO
LBI
R
SET
GND
8
7
6
5
FB
SHDN
V
IN
SW
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125
C,
JA
= 160
C/W
Consult factory for Military grade parts.
ELECTRICAL C
C
HARA TERISTICS
Commercial grade 0
C to 70
C, Industrial grade 40
C to 85
C, V
IN
= 2V, V
SHDN
= V
IN
, T
A
= 25
C unless otherwise noted. (Notes 1, 2)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Minimum Operating Voltage
1.5
1.65
V
Maximum Operating Voltage
12
V
Quiescent Current
V
SHDN
= 2V, Not Switching
33
45
A
q
50
A
Quiescent Current in Shutdown
V
SHDN
= 0V, V
IN
= 2V
q
3
5
A
V
SHDN
= 0V, V
IN
= 5V
q
7
10
A
FB Pin Bias Current
q
3
30
nA
Line Regulation
V
IN
= 1.8V to 12V
q
0.04
0.15
%/V
LBI Input Threshold
Falling Edge
q
1.1
1.17
1.25
V
LBI Pin Bias Current
q
3
20
nA
LBI Input Hysteresis
q
35
65
mV
LBO Output Voltage Low
I
SINK
= 500
A
q
0.2
0.4
V
LBO Output Leakage Current
LBI = 1.7V, LBO = 5V
q
0.01
0.1
A
SHDN Input Voltage High
q
1.4
V
SHDN Input Voltage Low
q
0.4
V
SHDN Pin Bias Current
V
SHDN
= 5V
q
2
5
A
V
SHDN
= 0V
q
1
3
A
LT1316CS8
LT1316IS8
1316
1316I
3
LT1316
ELECTRICAL C
C
HARA TERISTICS
Commercial grade 0
C to 70
C, Industrial grade 40
C to 85
C, V
IN
= 2V, V
SHDN
= V
IN
, T
A
= 25
C unless otherwise noted. (Notes 1, 2)
Load Transient Response
Burst Mode
TM
Operation
V
OUT
100mV/DIV
AC COUPLED
V
OUT
100mV/DIV
AC COUPLED
V
SW
5V/DIV
INDUCTOR
CURRENT
200mA/DIV
1316 G01
1316 G02
Burst Mode IS A TRADEMARK OF LINEAR TECHNOLOGY
CORPORATION.
Commercial grade 0
C to 70
C, V
IN
= 2V, V
SHDN
= V
IN
, T
A
= 25
C unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Switch OFF Time
FB > 1V
1.4
2.0
2.6
s
q
1.1
3.0
s
FB < 1V
3.4
s
Switch ON Time
Current Limit Not Asserted
4.4
6.3
8.2
s
1V < FB < 1.2V
q
3.4
9.5
s
Maximum Duty Cycle
Current Limit Not Asserted
74
76
90
%
1V < FB < 1.2V
q
73
90
%
Switch Saturation Voltage
I
SW
= 0.5A
q
0.30
0.4
V
I
SW
= 0.1A
q
0.06
0.15
V
Switch Leakage
Switch Off, V
SW
= 5V
q
0.1
5
A
FB Comparator Trip Point
q
1.21
1.23
1.25
V
Peak Switch Current
R
SET
= 27.4k, T
A
= 25
C
90
100
110
mA
R
SET
= 27.4k, T
A
=0
C
90
100
115
mA
R
SET
= 27.4k, T
A
= 70
C
70
90
110
mA
R
SET
= 10K
q
250
290
340
mA
R
SET
= 121k
25
mA
FB Comparator Trip Point
q
1.205
1.23
1.255
V
Peak Switch Current
R
SET
= 27.4k,
q
70
100
125
mA
R
SET
= 10k
q
200
290
370
mA
Industrial grade 40
C to 85
C, V
IN
= 2V, V
SHDN
= V
IN
, T
A
= 25
C unless otherwise noted.
over the 40
C to 85
C temperature range by design or correlation, but
are not production tested.
Note 2: I grade device specifications are guaranteed over the 40
C to
85
C temperature range.
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
0mA
50mA
I
LOAD
The
q
denotes specifications which apply over the specified temperature
range.
Note 1: C grade device specifications are guaranteed over the 0
C to 70
C
temperature range. In addition, C grade device specifications are assured
4
LT1316
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
SWITCH CURRENT (mA)
0
SWITCH SATURATION VOLTAGE (mV)
500
400
300
200
100
0
300
500
800
1316 G03
100 200
400
600 700
100
C
40
C
75
C
25
C
Switch Saturation Voltage
vs Switch Current
TEMPERATURE (
C)
50
LBI PIN CURRENT (nA)
8
6
4
2
0
25
0
25
50
1316 G04
75
100
Off-Time vs Temperature
TEMPERATURE (
C)
50
OFF-TIME (
s)
4
3
2
1
0
25
0
25
50
1316 G05
75
100
TEMPERATURE (
C)
50
MAXIMUM ON-TIME (
s)
8
7
6
5
25
0
25
50
1316 G06
75
100
Maximum On-Time
vs Temperature
Quiescent Current vs Temperature
TEMPERATURE (
C)
50
QUIESCENT CURRENT (
A)
36
34
32
30
28
26
25
0
25
50
1316 G07
75
100
Feedback Voltage vs Temperature
TEMPERATURE (
C)
50
FEEDBACK VOLTAGE (V)
1.240
1.235
1.230
1.225
1.220
25
0
25
50
1316 G08
75
100
LBI Pin Bias Current
vs Temperature
10
PEAK SWITCH CURRENT (mA)
100
1000
TEMPERATURE (
C)
50
25
0
25
50
1316 G10
75
100
R
SET
= 4.84k
R
SET
= 27.4k
R
SET
= 97.3k
R
SET
= 10k
Shutdown Pin Bias Current
vs Shutdown Pin Voltage
FB Pin Bias Current
vs Temperature
Peak Switch Current
vs Temperature
SHUTDOWN PIN VOLTAGE (V)
0
SHUTDOWN PIN CURRENT (
A)
4
3
2
1
0
1
1
2
3
4
1316 G09
5
6
TEMPERATURE (
C)
50
FB PIN BIAS CURRENT (nA)
4
3
2
1
25
0
25
50
1316 G11
75
100
5
LT1316
PI
N
FU
N
CTIO
N
S
U
U
U
LBO (Pin 1): Low-Battery Detector Output. Open collector
can sink up to 500
A. Low-battery detector remains active
in shutdown mode.
LBI (Pin 2): Low-Battery Detector Input. When voltage at
this pin drops below 1.17V, LBO goes low.
R
SET
(Pin 3): A resistor between R
SET
and GND programs
peak switch current. The resistor value should be between
3k and 150k. Do not float or short to ground. This is a high
impedance node. Keep traces at this pin as short as
possible. Do not put capacitance at this pin.
GND (Pin 4): Ground. Connect directly to ground plane.
SW (Pin 5): Collector of NPN Power Transistor. Keep
traces at this pin as short as possible.
V
IN
(Pin 6): Input Supply. Must be bypassed close to the
pin.
SHDN (Pin 7): Shutdown. Ground this pin to place the part
in shutdown mode (only the low-battery detector remains
active). Tie to a voltage between 1.4V and 6V to enable the
device. SHDN pin is logic level and need only meet the
logic specification (1.4V for high, 0.4V for low).
FB (Pin 8): Feedback Pin. Reference voltage is 1.23V.
Connect resistive divider tap here. Minimize trace area at
FB. Set V
OUT
according to: V
OUT
= 1.23V(1 + R1/R2).
+
+
1.17V
A3
LBI
A2
DRIVER
LB0
L1
R3 = 10R4
1.5V
UNDERVOLTAGE
LOCKOUT
D1
C1
R5
R4
0.5V
Q2
1
R2
R1
V
OUT
V
IN
Q1
200
OSCILLATOR
6.3
s ON
2
s OFF
+
+
V
REF
1.23V
FB
2
3
4
7
8
5
6
1
A4
R
SET
V
IN
SW
GND
1316 F01
SHDN
A1
Figure 1. LT1316 Block Diagram
BLOCK DIAGRA
W
6
LT1316
APPLICATIO
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FOR
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ATIO
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10
s/DIV
1316 F02
Figure 2. Switching Waveforms
R
SET
(k
)
10
DC CURRENT LIMIT (mA)
100
1000
10
100
1316 F03
Figure 3. DC Current Limit vs R
SET
Resistor
Note: DC Current is the Peak Switch Current if the Power
Transistor had Zero Turn-Off Delay
V
OUT
AC COUPLED
200mV/DIV
V
SW
5V/DIV
INDUCTOR
CURRENT
100mA/DIV
During the portion of the switch cycle when Q1 is turned
off, current is forced through D1 to C1 causing output
voltage to rise. This switching action continues until
output voltage rises enough to overcome A1's hysteresis.
Peak switch current is set by a resistor from the R
SET
pin
to ground. Voltage at the R
SET
pin is forced to 0.5V by A4
and is used to set up a constant current through R5. This
current also flows through R3 which sets the voltage at the
positive input of comparator A2. When Q1 turns on, the
SW pin goes low and current ramps up at the rate V
IN
/L.
Current through Q2 is equal to Q1's current divided by 200.
When current through Q2 causes the voltage drop across
R4 and R3 to be equal, A2 changes state and resets the
oscillator, causing Q1 to turn off. Shutdown is accom-
plished by grounding the SHDN pin.
The low-battery detector A3 has its own 1.17V reference
and is always on. The open collector output device can sink
up to 500
A. Approximately 35mV of hysteresis is built
into A3 to reduce "buzzing" as the battery voltage reaches
the trip level.
Current Limit
During active mode when the part is switching, current in
the inductor ramps up each switch cycle until reaching a
preprogrammed current limit. This current limit value
must be set by placing the appropriate resistor from the
R
SET
pin to ground. This resistance value can be found by
using Figure 3 to locate the desired DC current limit and
Table 1 simplifies component selection for commonly
used input and output voltages. The methods used in
determining these values are discussed in more detail later
in this data sheet.
V
OUT
can be set using the equation:
V
OUT
= 1.23
R2 + R1
R2
)
)
R1
V
OUT
R2
1316 EQF01
FB
Table 1. R
SET
Resistor and Inductor Values
LOAD
R
SET
PEAK SWITCH
V
IN
V
OUT
CURRENT
RESISTOR
INDUCTOR
CURRENT
2
5
10mA
36.8k
100
H
80mA
2
5
25mA
18.2k
68
H
165mA
2
5
50mA
10k
47
H
320mA
2
5
75mA
6.81k
33
H
500mA
5
12
100mA
6.81k
82
H
490mA
5
28
1mA
75k
100
H
56mA
5
28
5mA
22.1k
100
H
140mA
5
28
10mA
10k
100
H
270mA
Operation
To understand operation of the LT1316, first examine
Figure 1. Comparator A1 monitors FB voltage which is
V
OUT
divided down by resistor divider network R1/R2.
When voltage at the FB pin drops below the reference
voltage (1.23V), A1's output goes high and the oscillator
is enabled. The oscillator has an off-time fixed at 2
s and
an on-time limited to 6.3
s. Power transistor Q1 is cycled
on and off by the oscillator forcing current through the
inductor to alternately ramp up and down (see Figure 2).
7
LT1316
APPLICATIO
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ATIO
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U
U
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then adding in the amount of overshoot that will occur due
to turn-off delay of the power transistor. This turn-off
delay is approximately 300ns.
Peak switch current = DC current limit from graph +
V
IN
/L(turn-off delay)
Example:
Set peak switch current to 100mA for: V
IN
= 2V,
L = 33
H
Overshoot = V
IN
/L(turn-off delay) = (2/33
H)(300ns)
= 18.2mA
Refer to R
SET
graph and locate
(100mA 18.2mA)
82mA
R
SET
33k
Calculating Duty Cycle
For a boost converter running in continuous conduction
mode, duty cycle is constrained by V
IN
and V
OUT
according
to the equation:
DC =
V
OUT
V
IN
+ V
D
V
OUT
V
SAT
+ V
D
where V
D
= diode voltage drop
0.4V and V
SAT
= switch
saturation voltage
0.2V.
If the duty cycle exceeds the LT1316's minimum specified
duty cycle of 0.73, the converter cannot operate in con-
tinuous conduction mode and must be designed for
discontinuous mode operation.
Inductor Selection and Peak Current Limit for
Continuous Conduction Mode
Peak current and inductance determine available output
power. Both must be chosen properly. If peak current or
inductance is increased, output power increases. Once
output power or current and duty cycle are known, peak
current can be set by the following equation, assuming
continuous mode operation:
I
PEAK
=
2(I
OUT
)
1 DC
(1)
Inductance can now be calculated using the peak current:
L =
(t
OFF
)
V
OUT
V
IN
+ V
D
0.4(I
PEAK
)
(2)
where t
OFF
= 2
s and V
D
= 0.4V.
As a result of equations 1 and 2, ripple current during
switching will be 40% of the peak current (see Figure 2).
Using these equations at the specified I
OUT
, the part is
delivering approximately 60% of its maximum output
power. In other words, the part is operating on a 40%
reserve. This is a safe margin to use and can be decreased
if input voltage and output current are tightly controlled.
For some applications, this recommended inductor size
may be too large. Inductance can be reduced but available
output power will decrease. Also, ripple current during
switching will increase and may cause discontinuous
operation. Discontinuous operation occurs when
inductor current ramps down to zero at the end of each
switch cycle (see Figure 4). Shown in Figure 5 is minimum
inductance vs peak current for the part to remain in
continuous mode.
Figure 5. Minimum Inductance vs Peak Current
for Continuous Mode Operation
PEAK CURRENT (mA)
10
10
MINIMUM INDUCTANCE FOR
CONTINOUS MODE OPERATION (
H)
100
1000
100
1000
1316 F05
5V TO 18V
5V TO 12V
2V TO 5V
2
s/DIV
Figure 4. Discontinuous Mode Operation
1316 F04
SW PIN
5V/DIV
0mA
INDUCTOR
CURRENT
100mA/DIV
8
LT1316
APPLICATIO
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M
ATIO
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W
U
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Discontinuous Mode Operation
A boost converter with a high V
OUT
:V
IN
ratio operates with
a high duty cycle in continuous mode. For duty cycles
exceeding the LT1316's guaranteed minimum specifica-
tion of 0.73, the circuit will need to be designed for
discontinuous operation. Additionally, very low peak cur-
rent limiting below 50mA may necessitate operating in this
mode unless high inductance values are acceptable. When
operating in discontinuous mode, a different equation
governs available output power. For each switch cycle, the
inductor current ramps down to zero, completely releas-
ing the stored energy. Energy stored in the inductor at any
time is equal to 1/2 LI
2
. Because this energy is released
each cycle, the equation for maximum power out is:
P
OUT(MAX)
= 1/2L(I
PEAK
2
)f
Where f =
+ t
OFF
1
I
PEAK
(L)
V
IN
V
SAT
)
)
When designing for very low peak currents (< 50mA), the
inductor size needs to be large enough so that on-time is
a least 1
s. On-time can be calculated by the equation:
On-Time =
I
PEAK
L
(V
IN
V
SAT
)
)
)
where V
SAT
= 0.2V.
Also, at these low current levels, current overshoot due to
power transistor turn-off delay will be a significant portion
of peak current. Increasing inductor size will keep this to
a minimum.
Design Example 1
Requirements: V
IN
= 2V, V
OUT
= 5V and I
LOAD
= 10mA.
1. Find duty cycle
DC =
V
OUT
V
IN
+ V
D
V
OUT
V
SAT
+ V
D
)
)
=
= 0.654
5 2 + 0.4
5 0.2 + 0.4
)
)
Because duty cycle is less than the LT1316 minimum
specification (0.73), the circuit can be designed for
continuous operation.
2.
I
PEAK
=
2(I
OUT
)
1 DC
=
= 58mA
2(10mA)
1 0.654
3. Find L
L =
V
OUT
V
IN
+ V
D
0.4(I
PEAK
)
)
)
=
= 293
H
5 2 + 0.4
0.4(58mA)
)
)
t
OFF
2
s
4. Find R
SET
resistor
Overshoot =
300ns
V
IN
L
)
)
=
= 1.8mA
2
330
H
)
)
Find R
SET
from Figure 3 for 58mA 1.8mA = 56.2mA
R
SET
47k
Design Example 2
Requirements: V
IN
= 3.3V, V
OUT
= 28V and I
LOAD
= 5mA.
1. Find duty cycle:
DC =
V
OUT
V
IN
+ V
D
V
OUT
V
SAT
+ V
D
)
)
=
= 0.89
28 3.3 + 0.4
28 0.2 + 0.4
)
)
Because duty cycle exceeds LT1316 minimum specifi-
cation of 73%, the circuit must be designed for discon-
tinuous operation.
2. Find P
OUT(MAX)
Multiply P
OUT
by 1.4 to give a safe operating margin
P
OUT(MAX)
= P
OUT
(1.4) = (5mA)(28V)(1.4) = 0.196W
3. Set the on-time to the data sheet minimum of 3.4
s and
find L
L =
(t
ON
2
)(V
IN
V
SAT
)
2
2P
OUT(MAX)
(t
ON
+ t
OFF
)
=
= 52
H
(3.4
s
2
)(3.3 0.2)
2
2(0.196W)(3.4
s + 2
s)
9
LT1316
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4. Find I
PEAK
for 3.4
s on-time
I
PEAK
=
= 0.202A
t
ON
(V
IN
V
SAT
)
L
=
3.4
s(3.3 0.2)
52
H
5. Find R
SET
resistor
Overshoot =
300ns
V
IN
L
)
)
=
300ns = 19mA
3.3
52
H
)
)
Find R
SET
from Figure 3 for 0.202A 19mA = 0.183A
R
SET
13k
These discontinuous mode equations are designed to
minimize peak current at the expense of inductor size. If
smaller inductors are desired peak current must be
increased.
Capacitor Selection
Low ESR (Equivalent Series Resistance) capacitors should
be used at the output of the LT1316 to minimize output
ripple voltage. High quality input bypassing is also
required. For surface mount applications AVX TPS series
tantalum capacitors are recommended. These have been
specifically designed for switch mode power supplies and
have low ESR along with high surge current ratings.
For through-hole applications Sanyo OS-CON capacitors
offer extremely low ESR in a small package size. If peak
switch current is reduced using the R
SET
pin, capacitor
requirements can be eased and smaller, higher ESR units
can be used. Ordinary generic capacitors can generally be
used when peak switch current is less than 100mA,
although output voltage ripple may increase.
Diodes
Most of the application circuits on this data sheet specify
the Motorola MBR0520L surface mount Schottky diode.
This 0.5A, low drop diode suits the LT1316 well. In lower
current applications, a 1N4148 can be used although
efficiency will suffer due to the higher forward drop. This
effect is particularly noticeable at low output voltages. For
higher output voltage applications, such as LCD bias
generators, the extra drop is a small percentage of the
output voltage so the efficiency penalty is small. The low
cost of the 1N4148 makes it attractive wherever it can be
used. In through-hole applications the 1N5818 is the all
around best choice.
Lowering Output Ripple Voltage
To obtain lower output ripple voltage, a small feedforward
capacitor of about 50pF to 100pF may be placed from
V
OUT
to FB as detailed in Figure 6. Ripple voltages with
and without the added capacitor are pictured in Figures
7 and 8.
V
IN
SW
R
SET
GND
FB
SHDN
LT1316
47
F
10k
R1
1M
1%
C1
100pF
R2
324k
1%
47
F
2
CELLS
L1
47
H
D1
V
OUT
1316 F06
+
+
SHUTDOWN
Figure 6. 2-Cell to 5V Step-Up Converter
with Reduced Output Ripple Voltage
10
LT1316
APPLICATIO
N
S I
N
FOR
M
ATIO
N
W
U
U
U
V
OUT
100mV/DIV
AC COUPLED
I
L
100mA/DIV
100
s/DIV
1316 F07
Figure 7. Switching Waveforms for the Circuit
Shown in Figure 7 Without C1. The Output Ripple
Voltage is Approximately 140mV
P-P
50
s/DIV
1316 F08
Figure 8. By Adding C1, Output Ripple Voltage
is Reduced to Less Than 80mV
P-P
I
L
100mA/DIV
V
OUT
100mV/DIV
AC COUPLED
1
F ceramic capacitor acts to smooth voltage spikes at
switch turn-on and turn-off. If the power source is far away
from the IC, inductance in the power source leads results
in high impedance at high frequency. A local high capaci-
tance bypass is then required to restore low impedance at
the IC.
Low-Battery Detector
The LT1316 contains an independent low-battery detector
that remains active when the device is shut down. This
detector, actually a hysteretic comparator, has an open
collector output that can sink up to 500
A. The compara-
tor also operates below the switcher's undervoltage lock-
out threshold, operating until V
IN
reaches approximately
1.4V.
Layout/Input Bypassing
The LT1316's high speed switching mandates careful
attention to PC board layout. Suggested component place-
ment is shown in Figure 9. The input supply must have low
impedance at AC and the input capacitor should be placed
as indicated in the figure. The value of this capacitor
depends on how close the input supply is to the IC. In
situations where the input supply is more than a few
inches away from the IC, a 47
F to 100
F solid tantalum
bypass capacitor is required. If the input supply is close to
the IC, a 1
F ceramic capacitor can be used instead. The
LT1316 switches current in pulses up to 0.5A, so a low
impedance supply must be available. If the power source
(for example, a 2 AA cell battery) is within 1 or 2 inches of
the IC, the battery itself provides bulk capacitance and the
1316 F09
8
7
6
5
4
3
2
1
LT1316
C
OUT
R
SET
V
IN
GND
V
OUT
L
D
C
IN
+
+
Figure 9. Suggested PC Layout
11
LT1316
TYPICAL APPLICATIO
N
S
N
U
Efficiency vs Load Current
LOAD CURRENT (mA)
1
40
EFFICIENCY (%)
50
60
70
80
10
100
1316 TA04
90
36V
IN
72V
IN
48V
IN
+
+
LT1316
LBI
LB0
FB
SHDN
7
1
2
R3
604k
1%
Q3
2N3904
48V
R2
1.30M
1%
R5
69.8k
1%
R6
121k
1%
R7
432k, 1%
Q2
MPSA92
8
3
4
6
R4
2M
R1
1.3M
C1
0.1
F
C2
0.022
F
C4
47
F
D2
1N4148
C3
47
F
D1
1N5817
T1
10:1:1
L3
2
1
6
7
4
3
L1
V
OUT
5V
50mA
5
Q1
D3
1N4148
V
IN
SW
R
SET
GND
T1 = DALE LPE-4841-A313 (605-665-9301)
L
PRI
: 2mH
R
DS(ON)
: 4.3
AT V
GS
= 2.5V
R6, Q2,R7 MUST BE PLACED NEXT
TO THE FB PIN
I
IN
= 190
A WHEN
V
IN
= 48V, I
LOAD
= 1mA
L2
V
A
1316 TA03
Nonisolated 48V to 5V Flyback Converter
12
LT1316
TYPICAL APPLICATIO
N
S
N
U
Positive-to-Negative Converter for LCD Bias
V
IN
V
IN
SW
R
SET
FB
7
6
5
D1
MMBD914
8
4
3
SHDN
LT1316
GND
C4
1
F
35V
R3
15k
C1
33
F
10V
2 CELLS
L1
33
H
C4: SPRAGUE 293D105X9035B2T
C5: SPRAGUE 293D225X0035B2T
L1: SUMIDA CD43-330
1316 TA06
SHUTDOWN
+
C5
2.2
F
35V
+
+
R1
3.3M
2.2M
C2
0.01
F
50V
R2
210k
CONTRAST
ADJUST
D3
MBR0530L
V
OUT
20V
6mA
C3
100pF
50V
C6
0.33
F
50V
D2
MMBD914
Battery-Powered Solenoid Driver
CAP GOOD
5V/DIV
V
ENERGIZE
5V/DIV
I
L1
200mA/DIV
V
CAP
10V/DIV
1316 TA09
500ms/DIV
When Solenoid Is Energized (V
ENERGIZE
High) Peak Input Current
Remains Low and Controlled, Maximizing Battery Life
V
IN
V
IN
SW
R
SET
FB
7
2
6
5
BAT-85
V
CAP
ZTX949
V
ENERGIZE
8
1
4
3
SHDN
LBI
LBO
LT1316
GND
20k
470k
C1
47
F
16V
2 CELLS
L1
47
H
C1: AVX TPS 47
F, 16V
C2: SANYO 50MV470GX
L1: SUMIDA CD43-470
1316 TA08
SHUTDOWN
CAP
GOOD
+
+
5k
1.3k
2N3904
6.8M
324K
47k
SOLENOID
1N4148
C2
470
F
50V
50k
13
LT1316
TYPICAL APPLICATIO
N
S
N
U
Super Cap Backup Supply
50V to 6V Isolated Flyback Converter
L1
47
H
D1
0.5A
1316 TA10
RUN
R
SET
33k
CONNECT TO
MAIN SUPPLY
5V
6mA
READY
1.00M
100pF
1M
R1
10k
C
IN
33
F
10V
1.00M
357k
324k
+
+
C
OUT
33
F
10V
TAJB330M010R
PANASONIC EEC-S5R5V104
C
IN
, C
OUT
:
C
SUP
:
+
C
SUP
0.1F
5.5V
75
MBR0520LT3
SUMIDA CD43-470
D1:
L1:
V
IN
SW
LT1316
SHDN
LBI
LBO
FB
7
2
1
6
5
8
4
3
R
SET
GND
+
LT1316
LBI
LB0
FB
SHDN
7
1
2
604k
1%
2N3904
1.30M
1%
69.8k
1%
12.7k
50k
8
3
4
6
2M
510k
+V
IN
25V TO
50V
0.1
F
0.022
F
100V
CERAMIC
1
F
16V
CERAMIC
1N4148
C1
100
F
16V
1N5817
T1
L
PRI
: 2mH
10:1:1
2
1
4
3
7
6
V
OUT
6V/20mA
75% EFFICIENCY
5
Q1
1N4148
V
IN
SW
R
SET
GND
C1 = SANYO OS-CON 100
F, 16V
Q1 = ZETEX ZVN 4424A
T1 = DALE LPE-4841-A313 (605-665-9301)
1316 TA11
+
14
LT1316
TYPICAL APPLICATIO
N
S
N
U
LCD Bias Generator with Output Disconnect in Shutdown
V
IN
V
IN
3.3V
SW
R
SET
7
8
6
5
MBR0540LT1
OPTIONAL CONNECTION
V
BAT
1.6V TO 3.5V
V
ADJ
(V
OUT
ADJUST)
0V TO 3.3V
4
3
SHDN
FB
LT1316
GND
11k
1%
L1
22
H
C1
22
F
6.3V
C1: AVX TAJA226M006R
C2: AVX TAJB335M035R
L1: MURATA LQH3C220K04
Q1: MMBT3906LT3
1316 TA12
SHUTDOWN
+
+
4.7M
150k
100pF
50V
CERAMIC
V
OUT
17.1V TO 19.8V
4mA
3.32M
1%
232k
1%
C2
3.3
F
35V
0.33
F
50V
CERAMIC
Q1
Universal Serial Bus (USB) to 5V/100mA DC/DC Converter
V
IN
V
IN
4V TO
7V
SW
R
SET
3
8
6
5
D1
7
4
SHDN
FB
LT1316
GND
R3
10k
R
B
100
L1
33
H
C1
10
F
10V
C1: 10
F 10V AVX TAJB106M010
C2: 33
F 10V AVX TPSC336M010
C3: 10
F ALUMINUM ELECTROLYTIC
D1: MBR0520LT1
L1: 33
H SUMIDA CD43 (OR COILCRAFT DO1608)
Q1: MPS1907A
1316 TA13
+
+
R2
1.00M
R1
324k
100pF
V
OUT
5V
100mA
C2
33
F
10V
+
C3
10
F
10V
Q1
15
LT1316
PACKAGE DESCRIPTIO
N
U
Dimensions in inches (millimeter) unless otherwise noted.
1
2
3
4
0.150 0.157**
(3.810 3.988)
8
7
6
5
0.189 0.197*
(4.801 5.004)
0.228 0.244
(5.791 6.197)
0.016 0.050
0.406 1.270
0.010 0.020
(0.254 0.508)
45
0
8
TYP
0.008 0.010
(0.203 0.254)
SO8 0996
0.053 0.069
(1.346 1.752)
0.014 0.019
(0.355 0.483)
0.004 0.010
(0.101 0.254)
0.050
(1.270)
TYP
DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
*
**
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
MSOP (MS8) 1197
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
0.021
0.006
(0.53
0.015)
0
6
TYP
SEATING
PLANE
0.007
(0.18)
0.040
0.006
(1.02
0.15)
0.012
(0.30)
REF
0.006
0.004
(0.15
0.102)
0.034
0.004
(0.86
0.102)
0.0256
(0.65)
TYP
1
2
3
4
0.192
0.004
(4.88
0.10)
8
7 6
5
0.118
0.004*
(3.00
0.102)
0.118
0.004**
(3.00
0.102)
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
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 circuits as described herein will not infringe on existing patent rights.
16
LT1316
1316f LT/TP 0298 4K PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1997
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
q
(408) 432-1900
FAX: (408) 434-0507
q
TELEX: 499-3977
q
www.linear-tech.com
TYPICAL APPLICATIO
N
S
N
U
Low Profile 2 Cell-to-28V Converter for LCD Bias
V
IN
SW
R
SET
FB
7
1
2
6
5
D1
8
4
3
SHDN
LBI
LBO
LT1316
GND
C2
1
F
35V
10k
C1
10
F
2 CELLS
V
IN
L1
22
H
V
OUT
28V
5mA
C1: MURATA GRM235Y5V106Z010
C2: SPRAGUE 293D105X9035B2T
C3: 0.33
F CERAMIC, 50V
C4: 100pF CERAMIC, 50V
D1: BAT-54
L1: MURATA LQH3C220K04
1316 TA05
SHUTDOWN
+
4.32M
C4
100pF
50V
204k
C3
0.33
F
50V
Bipolar LCD Bias Supply
V
IN
V
IN
3.3V TO
4.2V
SW
R
SET
8
6
5
1N914
7
4
SHDN
FB
LT1316
GND
3
47k
L1
47
H
C1
22
F
16V
C4
3.3
F
35V
1316 TA14
+
+
1.00M
88.7k
(BAT54 = TWO DIODES IN SOT23)
BAT54
2
100pF
13V
0.5mA
15V
1.5mA
C3
1
F
35V
C2
1
F
35V
+
+
2N3904
22k
10k
C1: AVX TAJB226M016R
C2, C3: AVX TAJA105K035R
C4: AVX TAJB335M035R
L1: MURATA LQH3C470
PART NUMBER
DESCRIPTION
COMMENTS
LTC
1163
Triple High Side Driver for 2-Cell Inputs
1.8V Minimum Input, Drives N-Channel MOSFETs
LTC1174
Micropower Step-Down DC/DC Converter
94% Efficiency, 130
A I
Q
, 9V to 5V at 300mA
LT1302
High Output Current Micropower DC/DC Converter
5V/600mA from 2V, 2A Internal Switch, 200
A I
Q
LT1304
2-Cell Micropower DC/DC Converter
Low-Battery Detector Active in Shutdown, 5V at 200mA for 2 Cells
LT1307
Single Cell Micropower 600kHz PWM DC/DC Converter
3.3V at 75mA from 1 Cell
LTC1440/1/2
Ultralow Power Single/Dual Comparators with Reference 2.8
A I
Q
, Adjustable Hysteresis
LTC1516
2-Cell to 5V Regulated Charge Pump
12
A I
Q
, No Inductors, 5V at 50mA from 3V Input
LT1521
Micropower Low Dropout Linear Regulator
500mV Dropout, 300mA Current, 12
A I
Q
RELATED PARTS
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