NX2116 Datasheet, PDF (4/14 Pages) Microsemi Corporation – SYNCHRONOUS PWM CONTROLLER WITH CURRENT LIMIT, POWER GOOD & OVER VOLTAGE

NX2116/2116A/2116B/2117/2117A
PIN DESCRIPTIONS
PIN SYMBOL
VCC
PIN DESCRIPTION
Power supply voltage. A high freq 1uF ceramic capacitor is placed as close as possible to
and connected to this pin and ground pin. The maximum rating of this pin is 5V.
This pin supplies voltage to high side FET driver. A high freq 0.1uF ceramic capacitor is
BST
placed as close as possible to and connected to these pins and respected SW pins.
GND
Ground pin.
This pin is the error amplifier inverting input. It is connected via resistor divider to the
FB
output of the switching regulator to set the output DC voltage. When FB pin voltage is
lower than 0.6V, hiccup circuit starts to recycle the soft start circuit after 2048 switching
cycles.
OCP
This pin is connected to the drain of the external low side MOSFET via resistor and is the
input of the over current protection(OCP) comparator. An internal current source 40uA 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. Once this threshold is
reached the Hdrv and Ldrv pins are latched out.
This pin is connected to source of high side FET and provides return path for the high side
SW
driver. It is also used to hold the low side driver low until this pin is brought low by the
action of high side turning off. LDRV can only go high if SW is below 1V threshold .
HDRV
High side gate driver output.
LDRV
Low side gate driver output.
PGOOD
An open drain output that requires a pull up resistor to Vcc or a voltage lower than Vcc.
When FB pin reaches 90% of the reference voltage PGOOD transitions from LO to HI
state.
EN
A resistor divider is connected from the respective switcher BUS voltages to these pins
that holds off the controller's soft start until this threshold is reached. An external low cost
Transistor can be connected to this pin for external enable control.
COMP
This pin is the output of error amplifier and is used to compensate the voltage control
feedback loop. This pin can also be used to perform a shutdown if pulled lower than 0.3V.
Rev. 3.0
4
03/14/06