MCP19035-AAAAESLASHMF datasheet(11/44 Pages) MICROCHIP

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 2012-2013 Microchip Technology Inc.

DS22326B-page 11

MCP19035

3.0

PIN DESCRIPTION

Description of the pins are listed in Table 3-1.

3.1

Shutdown Input Pin (SHDN)

This pin enables or disables the MCP19035 device.

When logic “High” is applied to this pin, the device is

enabled. A logic “Low” will disable the device. When

the device is disabled, both the LDRV and HDRV pins

are held low. The internal LDO regulator is also dis-

abled when the SHDN pin is pulled low. Do not let this

pin float. If not used, connect to VIN using a 100 k

resistor.

3.2

Feedback Voltage Input Pin (FB)

This is the internal error amplifier’s negative input, and

is used to sense the output voltage. The positive input

to the amplifier is connected to the internal reference

voltage.

3.3

Internal Error Amplifier Pin

(COMP)

This is the output of the internal error amplifier. The

compensation network is connected between this pin

and the FB pin.

3.4

Input Voltage Pin (VIN)

This pin is the input power for the controller. A bypass

capacitor must be connected between this pin and the

GND pin. The input of an internal voltage regulator

(LDO) is connected to this pin to generate the +5V VCC

used for internal circuitry bias.

3.5

Power Good Pin (PWRGD)

The power good pin is an open drain output. This pin is

pulled low when the output is 90% less than the typical

value. Connect this pin to +VCC pin through a pull-up

resistor. The recommended value for the pull-up resis-

tor is 100 kΩ.

3.6

LDO Output Voltage Pin (+VCC)

This pin is the output of the internal voltage regulator

(LDO). The internal circuitry of the controller is powered

from this pin (+5.0V). External low noise loads can be

powered from this pin, but the sum of the external load

current and the internal circuitry current should not

exceed 50 mA. A 4.7 μF ceramic capacitor must be

connected between this pin and GND.

3.7

Lower Gate Pin (LDRV)

This pin is the drive output for the low-side N-Channel

MOSFET (synchronous rectifier). The LDRV drive is

capable of sourcing 1A and sinking 1.5A.

3.8

Bootstrap Supply Pin (BOOT)

The BOOT pin is the floating bootstrap power supply

pin for the high-side MOSFET gate driver. A capacitor

connected between this pin and the PHASE pin pro-

vides the necessary charge to turn on the external

high-side MOSFET.

TABLE 3-1:

PIN DESCRIPTION TABLE

MCP19035

3x 3 DFN

Symbol

Description

SHDN

Device shutdown input pin

Feedback voltage input pin

COMP

Internal error amplifier output pin

4VIN

Input voltage pin

PWRGD

Power good pin

6+VCC

+5.0V output voltage pin

LDRV

Lower gate drive output pin

BOOT

Floating bootstrap supply pin

PHASE

Switching node pin

HDRV

Upper gate drive output pin

Exposed Thermal Pad, must be connected to GND

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