nx2138 Microsemi Corporation, nx2138 Datasheet - Page 5

• Manufacturer Part Number: nx2138
• Description: Single Channel Mobile Pwm Controller
• Manufacturer: Microsemi Corporation

PIN DESCRIPTIONS
Rev. 1.6
12/09/09
PIN NUMBER PIN SYMBOL
10
11
12
13
14
15
16
17
1
2
3
4
5
6
7
8
9
PGOOD
OCSET
ENSW/
MODE
AGND
PGND
VOUT
PVCC
HDRV
LDRV
VCC
TON
BST
PAD
SW
NC
NC
FB
This pin is directly connected to the output of the switching regulator and
senses the VOUT voltage. An internal MOSFET discharges the output during
turn off.
This pin supplies the internal 5V bias circuit. A 1uF X7R ceramic capacitor is
placed as close as possible to this pin and ground pin.
This pin is the error amplifiers inverting input. This pin is connected via
resistor divider to the output of the switching regulator to set the output DC
voltage from 0.75V to 3.3V.
PGOOD indicator for switching regulator. It requires a pull up resistor to Vcc
or lower voltage. When FB pin reaches 90% of the reference voltage
PGOOD transitions from LO to HI state.
Not used.
Analog ground.
Power ground.
Low side gate driver output.
Provide the voltage supply to the lower MOSFET drivers. Place a high
frequency decoupling capacitor 1uF X5R to this pin.
This pin is connected to the drain of the external low side MOSFET and is
the input of 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.
This pin is connected to source of high side FETs and provide return path for
the high side driver. It is also the input of zero current sensing comparator.
High side gate driver output.
This pin supplies voltage to high side FET driver. A high freq 1uF X7R
ceramic capacitor and 2.2ohm resistor in series are recommended to be
placed as close as possible to and connected to this pin and SW pin.
Not used.
Switching converter enable input. Connect to VCC for PFM/Non synchronous
mode, connected to an external resistor divider equals to 70%VCC for ultra-
sonic, connected to GND for shutdown mode, floating or connected to 2V for
the synchronous mode.
VIN sensing input. A resistor connects from this pin to VIN will set the fre-
quency. A 1nF capacitor from this pin to GND is recommended to ensure the
proper operation.
Used as thermal pad. Connect this pad to ground plane through multiple vias.
PIN DESCRIPTION
NX2138
5