Copyright

 ANPEC Electronics Corp. Rev. A.

Rev.A.1 - Dec., 2001

APW7055

www.anpec.com.tw

4

Functional Pin Description

VCC (Pin 1)

Provide a +5V bias supply for the IC to this pin. This

pin also provides the gate bias charge for the MOS

FETs of the source-sink regulator. The voltage at th

is pin is monitored for Power-On Reset (POR)

purposes.

SS (Pin 2)

This pin provides the soft start for the standard buck

converter and source-sink regulator. Connect a ca-

pacitor from this pin to ground.This capacitor, along

with an internal 28uA current source,sets the soft-start

interval of the converter and preventing the outputs from

overshoot as well as limiting the input current .

SD (Pin 3)

T

he pin shuts down all the outputs. A TTL-compatible,

logic level high signal applied at this pin immediately

discharges the soft-start capacitor,disabling all the

outputs.When IC re-enabled, the IC undergoes a new

soft-start cycle.Left open, this pin is pulled low by an

internal pull-down resistor,enabling operation.

SOURCE (Pin 4)

Connect the pin to the upper MOSFET gate drive of

the source-sink regulator. This pin is used to drive the

1. Recommended operating conditions, Unless otherwise noted.

2. Refer to Block and Simplified Power System Diagrams , and Typical Application Schematic.

APW7055

Symbol

Parameter

Test Conditions

Min.

Typ.

Max.

Unit

Protection

VSEN Rising

115

120

VSEN O.V. Hysteresis

2

%

I

OCSET

Ocset Current Source

Vocset=3V

170

200

230

I

SS

Soft start Current

28

uA

upper external MOSFET as a source regulator.

SINK (Pin 5)

Connect the pin to the lower MOSFET gate drive of

the source-sink regulator.This pin is used to drive the

lower external MOSFET as a sink regulator.

FB (Pin 6)

Connect this pin to output of the source-sink regulator.

This pin provide the voltage feedback path for source

and sink regulators. This pin is internally connected

to the negative input of the source controller, and also

connected to the positive input of the sink controller.

VIN (Pin 7)

Connect this pin to a voltage source. Two voltages,

above 0.5VIN, are generated by an internal resistor

divider as the reference voltage of the source and sink

controllers. The internal resistor divider provides an

offset voltage to ensure higher sink regulation voltage

and prevent an direct current path through the upper

and lower MOSFETs, damaging the two MOSFETs.

GND (Pin 8)

Signal ground for the IC. All voltage levels are mea

sured with respect to this pin voltage protection.

Electrical Characteristics (Cont.)