Datasheet

SW
BST
RTN
V
CC
FB
SS
V
IN
10
9
8
7
6
5
4
3
2
1
RON/SD
SGND
ISEN
LM34914
SNVS453B –MAY 2006–REVISED MARCH 2013 www.ti.com
Connection Diagram
10-Lead WSON
PIN DESCRIPTIONS
Pin Number Name Description Application Information
Internally connected to the buck switch source. Connect to
1 SW Switching Node
the inductor, diode, and bootstrap capacitor.
Connect a 0.022 µF capacitor from SW to this pin. The
2 BST Boost pin for bootstrap capacitor
capacitor is charged each off-time via an internal diode.
The re-circulating current flows out of this pin to the free-
3 ISEN Current sense
wheeling diode.
Re-circulating current flows into this pin to the current sense
4 SGND Sense Ground
resistor.
Ground for all internal circuitry other than the current limit
5 RTN Circuit Ground
detection.
Feedback input from the regulated Internally connected to the regulation and over-voltage
6 FB
output comparators. The regulation level is 2.5V.
An internal current source charges an external capacitor to
7 SS Softstart
2.5V, providing the softstart function.
An external resistor from VIN to this pin sets the buck switch
8 RON/SD On-time control and shutdown
on-time. Grounding this pin shuts down the regulator.
Nominally regulated at 7.0V. Connect a 0.1 µF capacitor from
this pin to RTN. An external voltage (8V to 14V) can be
9 V
CC
Output from the startup regulator
applied to this pin to reduce internal dissipation. An internal
diode connects VCC to VIN.
10 VIN Input supply voltage Operating input range is 8.0V to 40V.
Exposed metal pad on the underside of the device. It is
EP Exposed Pad 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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