Copyright ANPEC Electronics Corp.
Rev. A.3 - Jul., 2005
APW7095/A
www.anpec.com.tw15
Function Descriptions
General
The APW7095/A provides voltage-mode feedback con-
trols for six DC/DC PWM converters(CH1 to CH6).
Each channel operates with an error amplifier, PWM
comparator, short-circuit comparator, ON/OFF con-
trol and output driver. An internal temperature-com-
pensated voltage provides reference voltages for each
channel. An triangular-wave oscillator(CT) with a tim-
ing resistor and capacitor generates triangular waves
to each channel. A inverting amplifier(CH4) cooper-
ates with the error amplifier for an inverting converter
(with negative output voltage) .
Reference Voltage
The APW7095 outputs a temperature- compensated
reference voltage(2.49V) at VREF pin. It is regulated
from the voltage at VCC pin and can source current of
max. 1mA to external loads. It also supplies bias for
the IC’s internal circuitry.
Triangular-wave Oscillator
The triangular-wave oscillator is designed to gener-
ates a triangular oscillation signal (CT) with amplitude
of 0.3V~0.8V at CT pin, providing signal to CH6. The
oscillator frequency is settable from 100kHz to 1MHz
and set by a timing resistor and a timing capacitor
connected respectively from RT and CT pins to ground.
Additional two triangular oscillation signals (CT1 and
CT2) are also internally generated with amplitude of 1.
1V~1.8V. The CT1 is in phase with the CT to the PWM
comparators of CH2 and CH4; the CT2 is out of phase
with the CT to the PWM comparators of CH1, CH3
and CH5.
Error Amplifier
The error amplifier is designed with unit-gain-bandwidth
of 1MHz and to satisfy wide application requirements.
It works with enternal resistor-capacitor network for
each converter’s feedback compensation. The loop gain
can be set by connecting a feedback resistor and
capacitor from the output pin(FB) to inverted input pin
of the error amplifier for stable operations.
Inverting Amplifier (Inv Amp)
The inverting amplifier detects the inverting DC/DC con-
verter output voltage (as a negative voltage) and out-
puts a control signal to the error amp.
Channel Control Function
The channel control function turns on/off one or more
channels depending on the states (“H” or “L” level) at
CTL, CTL1,2 to CTL5 pins. The on/off control logic is
shown as the following table:
Voltage Level at CTL Pin Channel ON/OFF State
CTL CTL1,2 CTL3 CTL4 CTL5 Power
/CH6 CH1
/CH2 CH3 CH4 CH6
Lx x x x OFF(Standby State)
LOFF
LHOFF ON
LOFF
LHH
OFF ON ON
LOFF
LHOFF ON
LOFF
L
HHH
OFF
ON ON ON
LOFF
LHOFF ON
LOFF
LHH
OFF ON ON
LOFF
LHOFF ON
LOFF
H
H
HHH
ON
ON
ON ON ON
Channel on/off Setting Table
Voltage Level at CTL Pin Channel ON/OFF State
CTL CTL1,2 CTL3 CTL4 CTL5 Power
/CH6 CH1
/CH2 CH3 CH4 CH6
Lx x x x OFF(Standby State)
LOFF
LHOFF ON
LOFF
LHH
OFF ON ON
LOFF
LHOFF ON
LOFF
L
HHH
OFF
ON ON ON
LOFF
LHOFF ON
LOFF
LHH
OFF ON ON
LOFF
LHOFF ON
LOFF
H
H
HHH
ON
ON
ON ON ON
Channel on/off Setting Table
MOSFET Drive Circuits
APW7095/A uses push-pull configuration at output of
each MOSFET driver for providing large drive current
to MOSFET gate. The following table shows the
MOSFETs connected to the drivers:
IC APW7095 APW7095A
CH1 OUT1-1 : PMOS
OUT1-2 : NMOS OUT1-1 : PMOS
OUT1-2 : NMOS
CH2 OUT2-1 : PMOS
OUT2-2 : NMOS OUT2-1 : NMOS
OUT2-2 : PMOS
CH3 OUT3 : NMOS OUT3 : NMOS
CH4 OUT4 : NMOS OUT4 : PMOS
CH5 OUT5-1 : NMOS
OUT5-2 : PMOS OUT5-1 : NMOS
OUT5-2 : PMOS
CH6 OUT6 : NMOS OUT6 : NMOS