Copyright

© ANPEC Electronics Corp.

Rev. A.4 - Jan., 2009

APW7108

www.anpec.com.tw

13

Pin Description (Cont.)

PIN

QFN-24

SSOP-28

NAME

FUNCTION

-

11

OCSET1

Current-limit threshold setting pin (PWM1). This pin is a buffered 0.9V internal reference

voltage. A resistor from this pin to the ground sets the current limit threshold for the

converter.

8

12

SOFT1

Soft-start and soft-stop interval setting pin. The SOFT1 pin can source 4.5µA in soft-start

process or sink 2.2

µA in soft-stop process. The SOFT1 current charges or discharges

the capacitor connected from the pin to the GND. The output voltage of the converter

follows the ramping-up/down voltage on the SOFT1 pin in the soft-start/soft-stop process

with the SOFT1 pin voltage as reference. When the SOFT1 pin voltage is higher than

internal reference 0.9V, the error amplifier will use the reference to regulate output

voltage. In the event of under-voltage, or EN1 shutdown, the SOFT1 is used by the

soft-stop function and then pulled down though a 2K resistor to the ground after the

falling SOFT1 voltage reaches about 50mV threshold. In soft-stop process, the converter

only has sinking capability even though the output voltage is below the regulated

voltage.

-

13

NC

No comment

9

14

VIN

Battery voltage input pin.

10

15

PG1

Power-good output pin of PWM 1. PGOOD1 is an open drain output used to indicate the

status of the output voltage. This pin is pulled low when the PWM 1 Converter output is

out of -11% ~ +15% of the set value.

11

16

PG2

Power-good output pin of PWM 2. The function is same as the PG1 pin.

12

17

SOFT2

Soft-start and soft-stop interval setting pin. The function is the same as the SOFT1 pin.

-

18

OCSET2

Current-limit threshold setting pin (PWM 2). This pin is a buffered 0.9V internal reference

voltage. A resistor from this pin to ground sets the current-limit threshold for the

converter.

13

19

VSEN2

Output voltage feedback pin. This pin is connected to the resistive divider that set the

desired output voltage for PWM 2. The PGOOD, UVP, and OVP circuits use this signal to

report output voltage status.

14

20

VOUT2

Selection pin for PWM 2 controller to operate in either forced PWM or automatic

PFM/PWM mode.

15

21

EN2

Enable pin of the PWM 2 controller. The PWM 2 is enabled when EN2 = 1. When both

EN1 and EN2 are low, the chip is disabled and only low leakage current is taken from

16

22

ISEN2

Current sense pin (PWM 2). This pin has the same function as ISEN1.

17

23

BOOT2

Supply Input for the UGATE2 Gate Driver and an internal level-shift circuit. Its function is

same as BOOT1.

18

24

UGATE2

Output of the high-side MOSFET driver (PWM 2). Connect this pin to Gate of the

high-side MOSFET.

19

25

PHASE2

Junction point of the high-side MOSFET source, output filter inductor and the low-side

MOSFET Drain. Connect this pin to the Source of the high-side MOSFET. PHASE2

serves as the lower supply rail for the UGATE2 high-side gate driver.

-

26

PGND2

Power ground of the LGATE2 low-side MOSFET driver. Connect the pin to the Source of

the low-side MOSFET.

20

27

LGATE2

Output of the low-side MOSFET driver (PWM 2). Connect this pin to Gate of the low-side

MOSFET. Swings from PGND2 or PGND to VCC.

21

28

VCC

Supply voltage input pin for control circuitry and both low-side MOSFET drivers.

7

-

OCSET

Current limit threshold setting pin for PWM1 and PWM 2. This pin is a buffered 0.9V

internal reference voltage. A resistor from this pin to the ground sets the current-limit

threshold for the converter.

Thermal

Pad

-

PGND

Power ground of the both channels’low-side MOSFET drivers. Connect the Sources of

the both channels' low-side MOSFETs to the IC thermal pad as close as possible.