AIC1571 AIC [Analog Intergrations Corporation], AIC1571 Datasheet - Page 9

• Manufacturer Part Number: AIC1571
• Description: 5-bit DAC, Synchronous PWM Power Regulator with Dual Linear Controllers
• Manufacturer: AIC [Analog Intergrations Corporation]

Pin 9: SS:
Pin 10: RT:
Pin 11: FB2:
Pin 12: VIN2:
Pin 13: GATE2: Linear Controller output drive pin.
Pin 14: GND:
Pin 15: GATE3: Linear Controller output drive pin.
Pin 16: FB3:
Pin 17: COMP1: External compensation pin. This
Soft-start pin. Connect a ca-
pacitor from this pin to ground.
This capacitor, along with an in-
ternal 10µA (typically) current
source, sets the soft-start inter-
val
Pulling this pin low will shut
down the IC.
Frequency adjustment pin. Con-
necting a resistor (RT) from this
pin to GND, increasing the fre-
quency. Connecting a resistor
(RT) from this pin to VCC, de-
creasing the frequency by the
following figure (Fig.3).
Connect this pin to a resistor di-
vider to set the linear controller
output voltage.
This pin is used to monitor the
3.3V supply. If, following a start-
up cycle, the voltage drops be-
low 2.6V (typically), the chip
shuts down. A new soft-start cy-
cle is initiated upon return of the
3.3V supply above the under-
voltage threshold.
This pin can drive either a Dar-
lington NPN transistor or a N-
channel MOSFET.
Signal GND for IC. All voltage
levels are measured with re-
spect to this pin.
This pin can drive either a Dar-
lington NPN transistor or a N-
channel MOSFET.
Negative feedback pin for the
linear controller error amplifier
connect this pin to a resistor di-
vider to set the linear controller
output voltage.
pin is connected to error ampli-
fier output and PWM comparator.
of
the
converter.
Pin 18: FB1:
Pin 19: VSEN:
Pin 20: OCSET: Current limit sense pin. Connect
Pin 21: PGND:
Pin 22: LGATE: Lower N-MOSFET gate drive pin.
Pin 23: PHASE: Over-current detection pin. Con-
Pin 24: UGATE: External high-side N-MOSFET
An RC network is connected to
FB1 in to compensate the volt-
age control feedback loop of the
converter.
The error amplifier inverting in-
put pin. the FB1 pin and COMP1
pin are used to compensate the
voltage-control feedback loop.
pin. Connect this pin to the con-
verter output. The PGOOD and
OVP comparator circuits use
this signal to report output volt-
age status and for over-voltage
protection function.
a resistor R
the drain of the external high-
side N-MOSFET. R
ternal 200µA current source
(I
MOSFET on-resistance (R
set the over-current trip point
according to the following equa-
tion:
Driver power GND pin. PGND
should be connected to a low
impedance
close
source.
nect the PHASE pin to source of
the
MOSFET. This pin detects the
voltage drop across the high-
side
over-current protection.
gate drive pin. Connect UGATE
to gate of the external high-side
N-MOSFET.
Converter output voltage sense
I
PEAK
OCSET
=
),
external
N-MOSFET
to
I
OCSET
and
OCSET
R
lower
ground
DS(ON)
×
the
AIC1571
R
from this pin to
high-side
OCSET
OCSET
R
N-MOSFET
upper
DS(ON)
plane
, an in-
DS(ON)
9
for
N-
N-
in
)