SC508/SC508A

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 pro-

gram the output voltage.

2

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 not exceed the VDDA pin. For output voltages up to 5V connect this pin

directly to the switcher output. For output voltages exceeding 5V connect this pin to the switcher output

through a resistor divider.

3

VDDA

Supply input for internal analog circuits — connect to external 5V supply or connect to VLDO — also the

sense input for VDDA Under Voltage Lockout (VDDA UVLO).

4

VLDO

Output of the 5V LDO — The voltage at this pin must not exceed the voltage at the VDDA pin.

5

VIN

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

tor from this pin to AGND to filter high frequency noise.

6

SS

Soft-Start — connect tan external capacitor to AGND to program the soft start and automatic recovery time.

7

NC

No Connection

8

BST

Bootstrap pin — connect a 100nF minimum capacitor and series resistor from BST to LX to develop the float-

ing voltage for the high-side gate drive. A 3.3 ohm resistor is recommended.

9

DH

High-side gate drive output

10

LX

Switching (phase) node

11

PGND

Power ground for the DL and DH drivers and the low-side external MOSFET.

12

DL

Low-side gate drive output

13

VDDP

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

14

PSV

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

quency — 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 (>1.7V) to enable the LDO and inhibit V

from VIN to AGND to program the V

PAD

AGND

Analog ground