AIC1580/L
BLOCK DIAGRAM
Over Current
-
+
PHASE
OCSET
200µA
SD
Power-On
Reset
Built-In Soft Start
VCC
REF
FB
COMP
+
-
Error AMP
PWM Comparator
+
-
Gate Control
UGATE
GND
Oscilator
PIN DESCRIPTIONS
PIN 1: OCSET - Current limit sense pin. Connect
a resistor R
OCSET
from this pin to
the drain of the external
MOSFET. R
OCSET
, an internal
200
µ
A current source (I
OCSET
),
and the external MOSFET on-
resistance (R
DS(ON)
) jointly set
the overcurrent
trip
point
according to the following
equation:
I
PEAK
=
I
OCSET
×
R
OCSET
R
DS(ON)
connected to FB pin to
compensate the voltage-control
feedback loop of the converter.
PIN 4: FB -
The error amplifier inverting
input pin. The FB pin and COMP
pin are used to compensate the
voltage-control feedback loop.
Ground pin.
Overcurrent
detection
pin.
Connect the PHASE pin to
source of the external N-
MOSFET. This pin detects the
voltage
drop
across
the
MOSFET R
DS(ON)
for overcurrent
protection.
PIN 5: GND-
PIN 6: PHASE-
If FB pin voltage is sensed to be
below 50% of the internal
voltage reference VDAC, the
overcurrent comparator cycles
the soft-start function.
PIN 2: SD
- Shutdown pin. Connect this pin
to ground for shutdown.
PIN 7: UGATE- External MOSFET gate drive pin.
Connect this pin to gate of the
external MOSFET.
PIN 8: VCC
-The chip power supply pin.
Recommended supply voltage is
12V.
PIN 3: COMP - External compensation pin. This
pin is connected to error
amplifier output and PWM
comparator. A RC network is
6
AIC [ ANALOG INTERGRATIONS CORPORATION ]
