Copyright ANPEC Electronics Corp. Rev. A.
Rev.A.1 - Dec., 2001
)29%##
www.anpec.com.tw4
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)
The 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 O.V. trip point (VSEN/V
DAC
) 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.)