PIN FUNCTIONS

N.

Name

Description

1

H5STRAP

+5.1V section bootstrap capacitor connection

Device supply voltage. From 5.5 to 25V

3

REG5

+5V regulator supply. Used mainly for bootstrap capacitors. It should be bypassed to ground.

4

V5SW

Alternative device supply voltage. When the +5.1V section is operating, the device is no

5

V5SNS

This pin connects to the (-) input of the +5.1V internal current sense comparator

6

I5SNS

This pin connects to the (+) input of the +5.1V internal current sense comparator

7

COMP5

Feedback input for the +5.1V section.

8

SOFT5

Soft-start input of the +5.1V section. The soft-start time is programmed by an external

capacitor connected between this pin and SGND. Approximately, 1ms/nF @ full load.

9

CRST

Input used for start-up and shut-down timing. A capacitor defines a time of 2ms/nF.

10

PWROK

Power-good diagnostic signal. This output is driven high when both switching sections are

enabled and running properly, after a delay defined by the CRST capacitor.

11

RUN5

Control input to enable/disable the 5.1V section. A high level (>2.4V) enables this section, a

low level (<0.8V) shuts it down

12

VREF

Internal +3.39V high accuracy voltage generator. It can source 5mA to external load. Bypass

to ground with a 4.7

µF capacitor to reduce noise.

13

SGND

Signal ground. Reference for internal logic circuitry. It must be routed separately from high

current returns.

14

NOSKIP

Pulse skipping mode control. A high level (>2.4V) disables pulse skipping at low load current,

a low level (<0.8V) enables it.

15

OSC

Oscillator frequency control: connect to 2.5V to select 300KHz operation, to ground or to 5V

for 200KHz operation. A proper external signal can synchronize the oscillator

16

RUN3

Control input to enable/disable the +3.3V section. A high level (>2.4V) enables this section, a

low level (>0.8V) shuts it down.

17

SOFT3

Soft-start input for the 3.3V section. The soft-start time is programmed by an external

capacitor connected between this pin and GND. Approximately, 1ms/nF @full load.

18

COMP3

Feedback input for the +3.3V section

19

I3SNS

This pin connects to the (+) input of the +3.3V internal current sense comparator

20

V3SNS

This pin connects to the (-) input of the +3.3V internal current sense comparator

21

V13IN

12V regulator input supply voltage, included between 13 and 20V. This voltage can be

supplied by a flyback winding on +3.3V inductor

22

REG12

12V regulator output voltage. It can source up to 150mA to an external load

23

SGND

To be connected to pin 13

24

H3STRAP

+3.3V section bootstrap capacitor connection

25

H3GATE

Gate- driver output for the +3.3V high-side N-MOS

26

H3SRC

+3.3V high-side N-MOS source connection

27

R3GATE

Gate- driver output for the +3.3V low- side N-MOS (synchronous rectifier).

28

PGND3

Current return for +3.3V section drivers

29

PGND5

Current return for +5.1V section drivers

30

R5GATE

Gate-driver output for the +5.1V low-side N-MOS (synchronous rectifier).

31

H5SRC

+5.1V high-side N-MOS source connection

32

H5GATE

Gate-driver output for the +5.1V high-side N-MOS

L4992

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