MCP16331 datasheet(10/40 Pages) MICROCHIP

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MCP16331

DS20005308B-page 10

 2014 Microchip Technology Inc.

3.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 3-1.

3.1

Switch Node (SW)

The switch node pin is connected internally to the

NMOS switch, and externally to the SW node

consisting of the inductor and Schottky diode. The

external Schottky diode should be connected close to

the SW node and GND.

3.2

Enable Pin (EN)

The EN pin is a logic-level input used to enable or

disable the device switching, and lower the quiescent

current while disabled. By default the MCP16331 is

enabled through an internal pull-up. To turn off the

device, the EN pin must be pulled low.

3.3

Ground Pin (GND)

The ground or return pin is used for circuit ground

connection. The length of the trace from the input cap

return, output cap return and GND pin should be made

as short as possible to minimize the noise on the GND

pin.

3.4

Feedback Voltage Pin (VFB)

The VFB pin is used to provide output voltage regulation

by using a resistor divider. The VFB voltage will be 0.8V

typical with the output voltage in regulation.

3.5

Boost Pin (BOOST)

The supply for the floating high side driver used to turn

the integrated N-Channel MOSFET on and off is

connected to the boost pin.

3.6

Power Supply Input Voltage Pin

(VIN)

Connect the input voltage source to VIN. The input

source should be decoupled to GND with a

4.7 µF - 20 µF capacitor, depending on the impedance

of the source and output current. The input capacitor

provides current for the switch node and a stable

voltage source for the internal device power. This

capacitor should be connected as close as possible to

the VIN and GND pins.

3.7

Exposed Thermal Pad Pin (EP)

There is an internal electrical connection between the

EP and GND pin for the TDFN package.

TABLE 3-1:

PIN FUNCTION TABLE

MCP16331

Symbol

Description

TDFN

SOT-23

Output switch node, connects to the inductor, freewheeling diode and the

bootstrap capacitor.

Enable pin. There is an internal pull up on the VIN. To turn the device off,

connect EN to GND.

—

Not connected

—

Not connected

GND

Ground pin

VFB

Output voltage feedback pin. Connect VFB to an external resistor divider to set

the output voltage.

BOOST

Boost voltage that drives the internal NMOS control switch. A bootstrap

capacitor is connected between the BOOST and SW pins.

VIN

Input supply voltage pin for power and internal biasing.

—

Exposed Thermal Pad

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