SC417/SC427

13

Pin Descriptions

Pin #

Pin Name

Pin Function

1FB

Feedback input for switching regulator used to program the output voltage — connect to an external resis-

tor divider from VOUT to AGND.

2

FBL

Feedback input for the LDO — connect to an external resistor divider from VLDO to AGND — used to pro-

gram the LDO output.

3

V5V

5V power input for internal analog circuits and gate drives — connect to external 5V supply or configure

the LDO for 5V and connect to VLDO.

4, 30, PAD 1

AGND

Analog ground

5

VOUT

Switcher output voltage sense pin — also the input to the internal switch-over between VOUT and VLDO.

The voltage at this pin must be less than or equal to the voltage at the V5V pin.

6, 9-11,

PAD 2

VIN

Input supply voltage

7

VLDO

LDO output — The voltage at this pin must be less than or equal to the voltage at the V5V pin.

8

BST

Bootstrap pin — connect a capacitor of at least 100nF from BST to LX to develop the floating supply for the

high-side gate drive.

12

DH

High-side gate drive — do not connect this pin

13

LXBST

LX Boost — connect to the BST capacitor.

23-25, PAD 3

LX

Switching (phase) node

14

DL

Low-side gate drive — do not connect this pin

15-22

PGND

Power ground

26

PGOOD

Open-drain power good indicator — high impedance indicates power is good. An external pull-up

resistor is required.

27

ILIM

Current limit sense pin — used to program the current limit by connecting a resistor from ILIM to LX.

28

LXS

LX sense — connects to R

ILIM

.

29

EN/PSV

Enable/power-save input for the switching regulator — connect to AGND to disable the switching regulator.

Float to operate in forced continuous mode (power-save disabled). SC417 — connect to V5V to operate with

ultra-sonic power-save mode enabled. SC427 — connect to V5V to operate with power-save mode enabled

with no minimum frequency.

31

TON

On-time programming input — set the on-time by connecting through a resistor to AGND

32

ENL

Enable input for the LDO — connect ENL to AGND to disable the LDO. Drive with logic to +3V for logic con-

trol, or program the VIN UVLO with a resistor divider between VIN, ENL, and AGND.