nx2155h Microsemi Corporation, nx2155h Datasheet - Page 4

• Manufacturer Part Number: nx2155h
• Description: Single Power Supply Synchronous Pwm Controller
• Manufacturer: Microsemi Corporation

PIN DESCRIPTIONS
Rev.1.1
04/16/09
PIN #
PAD
10
7
5
6
9
8
3
1
2
4
PIN SYMBOL
RT
5VREG
VIN
FB
COMP
BST
OCP
SW
HDRV
GND
LDRV
An internal 5V regulator provides supply voltage for the low side fet driver, BST
and internal logic circuit. A high frequency 4.7uF X5R ceramic capacitor must
be connected from this pin to the GND pin as close as possible.
Voltage supply for the internal 5V regulator. A high freuqncy 0.1uF ceramic ca-
pacitor must be connected from this pin to GND.
This pin is the error amplifier inverting input. This pin is also connected to the
output UVLO comparator. When this pin falls below threshold, both HDRV and
LDRV outputs are in hiccup.
This pin is the output of the error amplifier and together with FB pin is used to
compensate the voltage control feedback loop. This pin is also used as a shut
down pin. When this pin is pulled below 0.3V, both drivers are turned off and
internal soft start is reset.
This pin supplies voltage to the high side driver. A high frequency
ceramic capacitor of 0.1 to 1 uF must be connected from this pin to SW pin.
This pin is connected to the drain of the external low side MOSFET and is the
input of the over current protection(OCP) comparator. An internal current source
is flown to the external resistor which sets the OCP voltage across the Rdson
of the low side MOSFET. Current limit point is this voltage divided by the Rds-
on.
This pin is connected to the source of the high side MOSFET and provides return
path for the high side driver.
High side MOSFET gate driver.
Ground pin.
Low side MOSFET gate driver.
Oscillator's frequency can be set by using an external resistor from this pin to
GND.
PIN DESCRIPTION
NX2155H
4