__________________________________________________________________________Pin Description

Multi-Output, Low-Noise Power-Supply

Controllers for Notebook Computers

6

_______________________________________________________________________________________

____________________________________Typical Operating Characteristics (continued)

1000

0.1

0.1

10

1000

100

SWITCHING FREQUENCY

vs. LOAD CURRENT

10

1

100

LOAD CURRENT (mA)

1

5.00

4.90

50

60

VL REGULATOR OUTPUT VOLTAGE

vs. OUTPUT CURRENT

4.98

OUTPUT CURRENT (mA)

0

4.94

4.92

30

40

4.96

10

20

ON3 = ON5 = 0V

2.510

2.480

2.485

56

REF OUTPUT VOLTAGE

vs. OUTPUT CURRENT

2.505

OUTPUT CURRENT (mA)

0

2.495

2.490

34

2.500

12

ON3 = ON5 = 0V

2ms/div

STARTUP WAVEFORMS

RUN

5V/div

3.3V OUTPUT

2V/div

TIME

5V/div

5V OUTPUT

5V/div

SEQ = VL, 0.015

μF CAPACITOR ON-TIME

4

1

CSH3

Current-Sense Input for the 3.3V SMPS. Current-limit level is 100mV referred to CSL3.

STEER

(MAX1631A/

MAX1634A)

Logic-Control Input for secondary feedback. Selects the PWM that uses a transformer and secondary

feedback signal (SECFB):

STEER = GND: 3.3V SMPS uses transformer

STEER = VL: 5V SMPS uses transformer

PIN

NAME

FUNCTION

2

CSL3

Current-Sense Input. Also serves as the feedback input in fixed-output mode.

12OUT

(MAX1630A/

32A/33A/35A)

1µF minimum.

3

FB3

Feedback Input for the 3.3V SMPS; regulates at FB3 = REF (approx. 2.5V) in adjustable mode. FB3 is a

Dual Mode input that also selects the 3.3V fixed output voltage setting when tied to GND. Connect FB3

to a resistor-divider for adjustable-output mode.