Datasheet

SW
BST
NC
NC
NC
NC
RTN
FB
SS
11
10
9
5
4
3
2
1
6
7 8
12
13
14
VCC
VIN
RON/SD
SGND
ISEN
SW
BST
RTN
VCC
FB
SS
VIN
10
9
8
7
6
5
4
3
2
1
RON/SD
SGND
ISEN
LM25010
SNVS419D –DECEMBER 2005–REVISED FEBRUARY 2013 www.ti.com
Connection Diagram
Pin Descriptions
PIN NUMBER NAME DESCRIPTION APPLICATION INFORMATION
WSON-10 HTSSOP-14
1 2 SW Switching node Internally connected to the buck switch source. Connect to
the inductor, free-wheeling diode, and bootstrap capacitor.
2 3 BST Boost pin for bootstrap Connect a capacitor from SW to the BST pin. The capacitor
capacitor is charged from VCC via an internal diode during the buck
switch off-time.
3 4 ISEN Current sense During the buck switch off-time, the inductor current flows
through the internal sense resistor, and out of the ISEN pin
to the free-wheeling diode. The current limit comparator
keeps the buck switch off if the ISEN current exceeds 1.25A
(typical).
4 5 SGND Current sense ground Re-circulating current flows into this pin to the current sense
resistor.
5 6 RTN Circuit ground Ground return for all internal circuitry other than the current
sense resistor.
6 9 FB Voltage feedback input from Input to both the regulation and over-voltage comparators.
the regulated output The FB pin regulation level is 2.5V.
7 10 SS Softstart An internal 11.5 µA current source charges the SS pin
capacitor to 2.5V to soft-start the reference input of the
regulation comparator.
8 11 RON/SD On-time control and An external resistor from VIN to the RON/SD pin sets the
shutdown buck switch on-time. Grounding this pin shuts down the
regulator.
9 12 VCC Output of the bias regulator The voltage at VCC is nominally equal to V
IN
for V
IN
< 8.9V,
and regulated at 7V for V
IN
> 8.9V. Connect a 0.47 µF, or
larger capacitor from VCC to ground, as close as possible to
the pins. An external voltage can be applied to this pin to
reduce internal dissipation if V
IN
is greater than 8.9V.
MOSFET body diodes clamp VCC to VIN if V
CC
> V
IN
.
10 13 VIN Input supply voltage Nominal input range is 6V to 42V. Input bypass capacitors
should be located as close as possible to the VIN and RTN
pins.
1, 7, 8, 14 NC No connection No internal connection. Can be connected to ground plane to
improve heat dissipation.
EP Exposed pad Exposed metal pad on the underside of the device. It is
recommended to connect this pad to the PC board ground
plane to aid in heat dissipation.
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
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