AIC1570 Datasheet, PDF (9/18 Pages) Analog Intergrations Corporation – 5-bit DAC, Synchronous PWM Power Regulator with LDO and Linear Controller

AIC1570
the other outputs are below their
under-voltage thresholds. The
PGOOD output is open for VID
codes that inhibit operation. See
Table 1.
Pin 8:
FAULT:
This pin is low during normal
operation, but it is pulled to VCC
in the event of an over-voltage or
over-current condition.
Pin 9: SS:
Soft-start pin. Connect a
capacitor from this pin to ground.
This capacitor, along with an
internal 10µA (typically) current
source, sets the soft-start
interval of the converter.
Pulling this pin low will shut
down the IC.
Pin 10: RT:
Frequency adjustment pin.
Connecting a resistor (RT) from
this pin to GND, increasing the
frequency. Connecting a resistor
(RT) from this pin to VCC,
decreasing the frequency by the
following figure (Fig.3).
Pin 11: FB2:
Connect this pin to a resistor
divider to set the linear regulator
output voltage.
Pin 12: VIN2:
This pin supplies power to the
internal regulator. Connect this
pin to a suitable 3.3V source.
Additionally, this pin is used to
monitor the 3.3V supply. If,
following a start-up cycle, the
voltage drops below 2.6V
(typically), the chip shuts down.
A new soft-start cycle is initiated
upon return of the 3.3V supply
above the under-voltage
threshold.
Pin 13: VOUT2: Output of the linear regulator.
Supplies current up to 500mA.
Pin 14: GND: Signal GND for IC. All voltage
levels are measured with respect
to this pin.
Pin 15: GATE3: Linear Controller output drive pin.
This pin can drive either a
Darlington NPN transistor or a
N-channel MOSFET.
Pin 16: FB3:
Negative feedback pin for the
linear controller error amplifier
connect this pin to a resistor
divider to set the linear controller
output voltage.
Pin 17: COMP1: External compensation pin. This
pin is connected to error
amplifier output and PWM
comparator. An RC network is
connected to FB1 in to
compensate the voltage control
feedback loop of the converter.
Pin 18: FB1:
The error amplifier inverting
input pin. the FB1 pin and
COMP1 pin are used to
compensate the voltage-control
feedback loop.
Pin 19: VSEN:
Converter output voltage sense
pin. Connect this pin to the
converter output. The PGOOD
and OVP comparator circuits
use this signal to report output
voltage status and for over-
voltage protection function.
Pin 20: OCSET: Current limit sense pin. Connect
a resistor R_OCSET from this pin to
the drain of the external high-
side N-MOSFET. R_OCSET, an
internal 200µA current source
(I_OCSET), and the upper N-
MOSFET on-resistance (R_DS(ON))
set the over-current trip point
according to the following
equation:
IPEAK
=
IOCSET × ROCSET
RDS(ON)
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