LM25007MMX Datasheet, PDF (3/19 Pages) Texas Instruments – LM25007 42V, 0.5A Step-Down Switching Regulator

LM25007
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Pin
Name
Description
1
SW
Switching Node
2
BST Boost Boot–strap
capacitor input
3
RCL Current Limit OFF time
programming pin
4
RTN Circuit Ground
5
FB
Feedback Signal from
Regulated Output
6
RON/SD On-time set pin
7
VCC Output from the internal
high voltage bias
regulator.
8
VIN
Input supply voltage
-
EP
Exposed pad, underside
of the WSON package
option
SNVS401C – JANUARY 2006 – REVISED FEBRUARY 2013
Pin Descriptions
Application Information
Power switching node. Connect to the inductor, bootstrap capacitor, and free-wheeling
diode.
An external capacitor is required between the BST and the SW pins. A 0.01µF ceramic
capacitor is recommended.
A resistor between this pin and RTN sets the off-time when current limit is detected.
The off-time is preset to 17 µs if FB = 0V .
This pin is connected to the inverting input of the internal regulation comparator. The
regulation threshold is 2.5V.
A resistor between this pin and VIN sets the switch on-time as a function of Vin. The
minimum recommended on-time is 300ns at the maximum input voltage.
If an auxiliary voltage is available to raise the voltage on this pin above the regulation
setpoint (7V), the internal series pass regulator will shutdown, reducing the IC power
dissipation. Do not exceed 14V. This output provides gate drive power for the internal
Buck switch. An internal diode is provided between this pin and the BST pin. A local
0.1uF decoupling capacitor is recommended.
Recommended operating range: 9V to 42V.
Exposed metal pad on the WSON package underside. It is recommended to connect
this pad to the PC board ground plane to aid in heat dissipation.
Typical Application Circuit and Block Diagram
12V -42V
C1
1 PF
C5
0.1 PF,
100V
R_ON
200k
SHUTDOWN
R2
100k
8
V_IN
7V SERIES
REGULATOR
LM25007
SD
V_{CC 7}
ON TIMER
START
UVLO
THERMAL
SHUTDOWN
6
COMPLETE
SD/ ^Ron
R_ON
OVER-VOLTAGE
COMPARATOR
+
2.875V -
2.5V
5
FB
+
-
REGULATION
COMPARATOR
START
MINIMUM OFF
TIMER
COMPLETE
SET
SQ
RQ
CLR
BST 2
UVLO ^SD
V_IN
LEVEL
SHIFT
DRIVER
SW 1
3
FB
R_CL ^RCL
COMPLETE
START
CURRENT LIMIT
OFF TIMER
+
-
0.725A
BUCK
SWITCH
CURRENT
SENSE
4 RTN
C3
0.1 PF
C4
0.01 PF
100 PH
L1
D1
10V
R3
3.01k
R5
1
R4
1k
C2
15 PF
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