nx2142 Microsemi Corporation, nx2142 Datasheet - Page 4

• Manufacturer Part Number: nx2142
• Description: Single Channel Pwm Controller With Feedforward And 5v Bias Regulator
• Manufacturer: Microsemi Corporation

PIN DESCRIPTIONS
Rev. 1.1
10/28/07
PIN SYMBOL
REGOUT
COMP
HDRV
LDRV
GND
VCC
BST
SW
VIN
FB
This pin supplies the internal 5V bias circuit. A 1uF high frequency ceramic X5R
capacitor must be placed as close as possible to this pin and ground pin to provide
high frequency bypass and to make the 5V regulator stable.
This pin supplies voltage to high side FET driver. A minimum 0.1uF ceramic high
frequency capacitor is placed as close as possible to and connected to this pin and
SW pin.
Power ground.
This pin is the error amplifiers inverting input. It is connected via resistor divider to
the output of the switching regulator to set the output DC voltage.
This pin is the output of the error amplifier and together with FB pin is used to compen-
sate the voltage control feedback loop. You can shutdown the switching regulator by
pulling this pin below 0.3V.
This pin is connected to source of high side FETs and provides return path for the
high side driver. This pin also provides input for the OCP comparator by sensing the
RDSON of the lower MOSFET. When this pin is below ground by 320mV, both drivers
are shutdown and enter hiccup mode.
High side gate driver output.
Low side gate driver output.
The output of the 5V regulator controller that drives a low current low cost external
bipolar transistor or an external MOSFET to regulate the voltage at Vcc pin derived
from bus voltage. This eliminates an otherwise external regulator needed in applica-
tions where 5V is not available. This regulator request a 1uF ceramic X5R type output
capacitor in order to be stable.
This pin provides the input voltage to the 5V regulator controller as well as the
oscillator for the PWM feed forward to work. When VIN exceeds 6V, the converter
starts to operate.
PIN DESCRIPTION
NX2142/2142A
4