Copyright ANPEC Electronics Corp.
Rev. A.4 - Dec., 2008
APW7095/A
www.anpec.com.tw15
Function Description
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 control, and output
driver. An internal temperature-compensated voltage pro-
vides reference voltages for each channel. An triangular-
wave oscillator(CT) with a timing resistor and capacitor
generates triangular waves to each channel. A inverting
amplifier(CH4) cooperates with the error amplifier for an
inverting converter (with negative output voltage) .
Reference Voltage
The APW7095 outputs a temperature- compensated ref-
erence 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 generates
a triangular oscillation signal (CT) with amplitude of
0.3V~0.8V at CT pin, providing signal to CH6. The oscilla-
tor frequency is settable from 100kHz to 1MHz and set by
a timing resistor and a timing capacitor connected re-
spectively from RT and CT pins to ground. Additional two
triangular oscillation signals (CT1 and CT2) are also in-
ternally 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 outputs 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
Lx x x x OFF(Standby State)
L
LH
L
LHH
L
LH
L
L
HHH
LOFF
LH
ON
LOFF
LHH
ON
LOFF
LH
L
H
H
HHH
Channel on/off Setting Table
Voltage Level at CTL Pin Channel ON/OFF State
Lx x x x OFF(Standby State)
L
LH
L
LHH
L
LH
L
L
HHH
LOFF
LH
ON
LOFF
LHH
ON
LOFF
LH
L
H
H
HHH
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
Timer-Latch Short-Circuit Protection Circuit
The short-circuit protection comparator in each channel
(CH1 to CH5) monitors converter’s output voltage via in-
put pin of error amplifier. In CH6, the short-circuit com-
parator detects the voltage at output of error amplifier. As
any detected voltages of CH1 to CH5 falls below 1.0V or
the detected voltage of CH6 is larger than 0.9V, the timer
circuits is actuated to start charging the external capacitor
CSCP connected from CSCP pin to ground. When the
rising voltage of CSCP reaches 0.7V, the IC turns off all