Dual-Output Power-Supply

Controller for Notebook Computers

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7

PIN

NAME

FUNCTION

1

CS3

Current-sense input for +3.3V; +100mV = current limit level referenced to FB3.

2

SS3

Soft-start input for +3.3V. Ramp time to full current limit is 1ms/nF of capacitance to GND.

3

ON3

ON/OFF control input disables the +3.3V PWM. Tie directly to VL for automatic start-up.

4

D1

#1 level-translator/comparator noninverting input, threshold = +1.650V. Controls Q1. Tie to GND if unused.

5

D2

#2 level-translator/comparator noninverting input (see D1)

6

VH

External positive supply-voltage input for the level translators/comparators

7

Q2

#2 level-translator/comparator output. Sources 20µA from VH when D2 is high. Sinks 500µA to GND

when D2 is low, even with VH = 0V.

8

Q1

#1 level translator/comparator output (see Q2)

9

GND

Low-current analog ground

10

REF

3.3V reference output. Sources up to 5mA for external loads. Bypass to GND with 1µF/mA of load or

0.22µF minimum.

11

SYNC

Oscillator control/synchronization input. Connect to VL or GND for 200kHz; connect to REF for

300kHz. For external clock synchronization in the 240kHz to 350kHz range, a high-to-low transition

causes a new cycle to start.

12

SHDN

Shutdown control input, active low. Tie to VL for automatic start-up. The 5V VL supply stays active in

shutdown, but all other circuitry is disabled. Do not force SHDN higher than VL + 0.3V.

13

ON5

ON/OFF control input disables the +5V PWM supply. Tie to VL for automatic start-up.

14

SS5

Soft-start control input for +5V. Ramp time to full current limit is 1ms/nF of capacitance to GND.

15

CS5

Current-sense input for +5V; +100mV = current-limit level referenced to FB5.

16

DH5

Gate-drive output for the +5V high-side MOSFET

17

LX5

Inductor connection for the +5V supply

18

BST5

Boost capacitor connection for the +5V supply (0.1µF)

19

DL5

Gate-drive output for the +5V low-side MOSFET

20

PGND

Power ground

21

FB5

Feedback and current-sense input for the +5V PWM

22

VL

5V logic supply voltage for internal circuitry. VL is always on and can source 5mA for external loads.

23

V+

Supply voltage input from battery, 5.5V to 30V

24

DL3

Gate-drive output for the +3.3V low-side MOSFET

25

BST3

Boost capacitor connection for the +3.3V supply (0.1µF)

26

LX3

Inductor connection for the +3.3V supply

27

DH3

Gate-drive output for the +3.3V high-side MOSFET

28

FB3

Feedback and current-sense input for the +5V PWM

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