LM2653
1.5A High Efficiency Synchronous Switching Regulator
General Description
The LM2653 switching regulator provides high efficient
power conversion over a 100:1 load range (1.5A to 15 mA).
This
feature
makes
the
LM2653
an
ideal
fit
in
battery-powered applications.
Synchronous rectification is used to achieve up to 97%
efficiency. At light loads, the LM2653 enters a low power
hysteretic or "sleep" mode to keep the efficiency high. In
many applications, the efficiency still exceeds 80% at 15 mA
load. A shutdown pin is available to disable the LM2653 and
reduce the supply current to 7A.
All the power, control, and drive functions are integrated
within the ICs. The ICs contain patented current sensing
circuity for current mode control. This feature eliminates the
external
current
sensing
resistor
required
by
other
current-mode DC-DC converters.
The ICs have a 300 kHz fixed frequency internal oscillator.
The high oscillator frequency allows the use of extremely
small, low profile components.
Protection features include thermal shutdown, input under-
voltage lockout, adjustable soft-start, cycle by cycle current
limit, output overvoltage and undervoltage protections.
Features
n
Efficiency up to 97%
n
4V to 14V input voltage range
n
1.5V to 5.0V adjustable output voltage
n
0.1
Switch On Resistance
n
300 kHz fixed frequency internal oscillator
n
7 A shutdown current
n
Patented current sensing for current mode control
n
Input undervoltage lockout
n
Output overvoltage shutdown protection
n
Output undervoltage shutdown protection
n
Adjustable soft-start
n
Adjustable PGOOD delay
n
Current limit and thermal shutdown
Applications
n
Webpad
n
Personal digital assistants (PDAs)
n
Computer peripherals
n
Battery-powered devices
n
Notebook computer video supply
n
Handheld scanners
n
GXM I/O and core voltage
n
High efficiency 5V conversion
Typical Application
Efficiency vs Load Current
(V
IN
= 5V, V
OUT
= 3.3V)
10104902
10104930
March 2001
LM2653
1.5A
High
Efficiency
Synchronous
Switching
Regulator
2001 National Semiconductor Corporation
DS101049
www.national.com
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Input Voltage
15V
PGOOD Pin Voltage
15V
Feedback Pin Voltage
-0.4V
V
FB
5V
Power Dissipation (T
A
=25C),
(Note 2)
893 mW
Junction Temperature
Range
-40C
T
J
+125C
Storage Temperature Range
-65C to +150C
Lead Temperature
M Package
Vapor Phase (60 sec.)
215C
Infrared (15 sec.)
220C
Maximum Junction Temperature
150C
ESD Susceptibility
Human Body Model (Note 3)
1 kV
Operating Ratings
(Note 1)
Supply Voltage
4V
V
IN
14V
Electrical Characteristics
Specifications with standard typeface are for T
J
= 25C, and those in boldface type apply over full Operating Temperature
Range. V
IN
= 10V unless otherwise specified.
Symbol
Parameter
Conditions
Typical
(Note 5)
Limit
(Note 4)
Units
V
FB
Feedback Voltage
I
LOAD
= 900 mA
1.238
1.200
1.263
V
V(min)
V(max)
V
OUT
Output Voltage Line
Regulation
V
IN
= 4V to 12V
I
LOAD
= 900 mA
0.2
%
Output Voltage Load
Regulation
I
LOAD
= 10 mA to 1.5A
V
IN
= 5V
1.3
%
Output Voltage Load
Regulation
I
LOAD
= 200 mA to 1.5A
V
IN
= 5V
0.3
%
V
INUV
V
IN
Undervoltage Lockout
Threshold Voltage
Rising Edge
3.8
3.95
V
V(max)
V
UV_HYST
Hysteresis for the Input
Undervoltage Lockout
210
mV
I
CL
Switch Current Limit
V
IN
= 5V
V
OUT
= 2.5V
2.0
1.55
2.60
A
A(min)
A(max)
I
SM
Sleep Mode Threshold
Current
V
IN
= 5V, V
OUT
= 2.5V
100
mA
V
HYST
Sleep Mode Feedback
Voltage Hysteresis
24
mV
I
Q
Quiescent Current
1.7
2.0
mA
mA(max)
I
QSD
Quiescent Current in
Shutdown Mode
Shutdown Pin Pulled Low
7
12/20
A
A(max)
R
DS(ON)
High-Side or Low-Side
MOSFET ON Resistance
I
SWITCH
= 1A
75
130
m
m
(max)
R
SW(ON)
High-Side or Low-Side
Switch On Resistance
(MOSFET ON Resistance +
Bonding Wire Resitstance)
I
SWITCH
= 1A
110
m
I
L
Switch Leakage
Current -- High Side
130
nA
Switch Leakge
Current -- Low Side
130
nA
LM2653
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2
Electrical Characteristics
(Continued)
Specifications with standard typeface are for T
J
= 25C, and those in boldface type apply over full Operating Temperature
Range. V
IN
= 10V unless otherwise specified.
Symbol
Parameter
Conditions
Typical
(Note 5)
Limit
(Note 4)
Units
V
BOOT
Bootstrap Regulator Voltage
I
BOOT
= 1 mA
6.75
6.45/6.40
6.95/7.00
V
V(min)
V(max)
G
M
Error Amplifier
Transconductance
1250
mho
A
V
Error Amplifier Voltage Gain
100
I
EA_SOURCE
Error Amplifier Source
Current
V
IN
= 3.6V, V
FB
= 1.17V, V
COMP
= 2V
40
25/15
A
A(min)
I
EA_SINK
Error Amplifier Sink Current
V
IN
= 3.6V, V
FB
= 1.31V, V
COMP
= 2V
65
30
A
A(min)
V
EAH
Error Amplifier Output Swing
Upper Limit
V
IN
= 4V, V
FB
= 1.17V
2.70
2.50/2.40
V
V(min)
V
EAL
Error Amplifier Output Swing
Lower Limit
V
IN
= 4V, V
FB
= 1.31V
1.25
1.35/1.50
V
V(max)
V
D
Body Diode Voltage
I
DIODE
= 1.5A
1
V
F
OSC
Oscillator Frequency
Measured at Switch Pin
V
IN
= 4V
300
280/255
330/345
kHz
kHz(min)
kHz(max)
D
MAX
Maximum Duty Cycle
V
IN
= 4V
95
92
%
%(min)
I
SS
Soft-Start Current
Voltage at the SS Pin = 1.4V
11
7
14
A
A(min)
A(max)
V
OUTUV
V
OUT
Undervoltage Lockout
Threshold Voltage
81
76
84
%V
OUT
%V
OUT
(min)
%V
OUT
(max)
Hysteresis for V
OUTUV
5
%V
OUT
V
OUTOV
V
OUT
Overvoltage Lockout
Threshold Voltage
108
106
114
%V
OUT
%V
OUT
(min)
%V
OUT
(max)
Hysteresis for V
OUTOV
3
%V
OUT
I
LDELAY__
SOURCE
LDELAY Pin Source Current
5
A
I
PGOOD__SINK
PGOOD Pin Sink Current
V
PGOOD
= 0.4V
15
mA(max)
I
PGOOD__LEAKAGE
PGOOD Pin Leakage
Current
V
PGOOD
= 5V
50
nA
I
SHUTDOWN
Shutdown Pin Current
Shutdown Pin Pulled Low
2.2
0.8/0.5
3.7/4.0
A
A(min)
A(max)
V
SHUTDOWN
Shutdown Pin Threshold
Voltage
Rising Edge
0.6
0.3
0.9
V
V(min)
V(max)
T
SD
Thermal Shutdown
Temperature
165
C
T
SD_HYST
Thermal Shutdown
Hysteresis Temperature
25
C
Note 1: Absolute Maxmum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but device parameter specifications may not be guaranteed under these conditions. For guaranteed specifications and test conditions, see
the Electrical Characteristics.
LM2653
www.national.com
3
Electrical Characteristics
(Continued)
Note 2: The maximum allowable power dissipation is calculated by using P
DMAX
= (T
JMAX
- T
A
)/
JA
, where T
JMAX
is the maximum junction temperature, T
A
is the
ambient temperature, and
JA
is the junction-to-ambient thermal resistance of the specified package. The 893 mW rating results from using 150C, 25C, and
140C/W for T
JMAX
, T
A
, and
JA
respectively. A
JA
of 140C/W represents the worst-case condition of no heat sinking of the 16-pin TSSOP package. Heat sinking
allows the safe dissipation of more power. The Absolute Maximum power dissipation must be derated by 7.14 mW per C above 25C ambient. The LM2653 actively
limits its junction temperatures to about 165C.
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 k
resistor into each pin.
Note 4: Typical numbers are at 25C and represent the most likely norm.
Note 5: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (bold typeface). All room temperature limits are 100%
production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used
to calculate Average Outgoing Quality Level (AOQL).
LM2653
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4
Typical Performance Characteristics
Efficiency vs Load Current
(V
IN
= 5V, V
OUT
= 2.5V)
l
Q
vs V
IN
I
QSD
vs Input Voltage
10104922
10104904
10104925
I
QSD
vs Junction Temperature
Frequency vs Junction Temperature
R
SW(ON)
vs Input Voltage
10104926
10104907
10104923
R
SW(ON)
vs Junction Temperature
Current Limit vs Input Voltage (V
OUT
= 2.5V)
Current Limit vs Junction
Temperature (V
OUT
= 2.5V)
10104924
10104927
10104928
LM2653
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5
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