SC418

11

Pin Descriptions

Pin #

Pin Name

Pin Function

1

FB

Feedback input for switching regulator — connect to an external resistor divider from output — used to

program the output voltage.

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

VDDA

Supply input for internal analog circuits — connect to external 3.3V or 5V supply, or configure the LDO for

3.3V or 5V and connect to VLDO — also the sense input for VDDA UVLO.

4

VOUT

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

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

5

NC

No Connection

6

VIN

Input supply voltage — connect to the same supply used for the high-side MOSFET. Connect a 100nF ca-

pacitor from this pin to AGND.

7

VLDO

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

8

BST

Bootstrap pin — connect a 100nF minimum capacitor from BST to LX to develop the floating voltage for the

high-side gate drive.

9

DH

High-side gate drive output

10

LX

Switching (phase) node

11

PGND

Power ground

12

DL

Low-side gate drive output

13

VDDP

Supply input for the DH and DL gate drives — connect to the same 3.3V or 5V supply used for VDDA.

14

PSV

Power-save programming input — connect a resistor to AGND to set a minimum (ultrasonic) power-save

frequency — float pin to select power-save with no minimum frequency — pull up to VDDA to disable

power-save and select forced continuous mode.

15

PGOOD

Open-drain Power Good indicator — high impedance indicates the switching regulator output is good. An

external pull-up resistor is required.

16

ILIM

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

17

EN

Enable input for switching regulator — logic low disables the switching regulator — logic high enables the

switching regulator.

18

AGND

Analog ground

19

TON

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

20

ENL

Enable input for the LDO and VIN UVLO input for the switching regulator — connect ENL to AGND to disable

the LDO — drive to logic high (>3V) to enable the LDO and inhibit VIN UVLO — connect to resistor divider

from VIN to AGND to program the V

PAD

AGND

Analog ground