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APW7015

Advanced PWM and Dual Linear Power Control

Anpec Electronics 

APW7015

Functional Pin Description (Cont.)

SS (Pin 10)

COMP and FB (Pin 17, and 18)

Connect a capacitor from this pin to ground. This

capacitor, along with an internal 28mA current source,

sets the soft-start interval of the converter.

FAULT (Pin 11)

This pin provides oscillator switching frequency

adjustment. By placing a resistor (RT) from this pin to

GND, the nominal 200kHz switching frequency is in-

creased according to the following equation:

Fs =200kHz + 5 ´ 10 6 / RT (kW) (RT to GND)

Conversely, connecting a resistor from this pin to VCC

reduces the switching frequency according to the fol-

lowing equation:

Fs =200kHz + 4 ´ 10 7 / RT (kW) (RT to 12V)

Nominally, the voltage at this pin is 1.26V. In the event

of an over-voltage or over-current condition, this pin

is internally pulled to VCC.

VAUX (Pin 13)

COMP and FB are the available external pins of the

PWM converter error amplifier. The FB pin is the in-

verting input of the error amplifier. Similarly, the COMP

pin is the error amplifier output. These pins are used

to compensate the voltage-mode control feedback

loop of the synchronous PWM converter.

VSEN1 (Pin 19)

This pin is connected to the PWM converter’s output

voltage. The PGOOD and OVP comparator circuits

use this signal to report output voltage status and for

over- voltage protection.

OCSET (Pin 20)

Connect a resistor from this pin to the drain of the

respective upper MOSFET. This resistor, an internal

200µA current source, and the upper MOSFET’s on-

resistance set the converter over-current trip point.

An over-current trip cycles the soft-start function.

The voltage at this pin is monitored for power-on re-

set (POR) purposes and pulling this pin low with an

open drain device will shutdown the IC.

This pin provides boost current for the linear

regulator’s output drives in the event bipolar NPN tran-

sistors (instead of N-channel MOSFETs) are em-

ployed as pass elements. The voltage at this pin is

monitored for power-on reset purposes.

PGND (Pin 21)

This is the power ground connection. Tie the syn-

chronous PWM converter’s lower MOSFET source

to this pin.

GND (Pin 14)

LGATE (Pin 22)

Signal ground for the IC. All voltage levels are mea-

sured with respect to this pin.

DRIVE3 (Pin 15)

Connect this pin to the gate of an external MOSFET.

This pin provides the drive for the FBVDDQ

regulator’s pass transistor.

VSEN3 (Pin 16)

Connect this pin to a resistor divider to set the linear

regulator (FBVDDQ) output voltage.

Connect LGATE to the PWM converter’s lower

MOSFET gate. This pin provides the gate drive for

the lower MOSFET.

PHASE (Pin 23)

Connect the PHASE pin to the PWM converter’s up-

per MOSFET source. This pin represents the gate

drive return current path and is used to monitor the

voltage drop across the upper MOSFET for over-cur-

rent protection.

Copyright  ANPEC Electronics Corp.

5

Rev. P.1 - Mar., 2000

www.anpec.com.tw

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