MCP16331 datasheet(14/48 Pages) MICROCHIP

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MCP16331

DS20005308D-page 14

 2014-2021 Microchip Technology Inc.

FIGURE 4-1:

MCP16331 Block Diagram.

4.2

Functional Description

4.2.1

STEP-DOWN OR BUCK CONVERTER

The MCP16331 device is a non-synchronous, step-down

or buck converter capable of stepping input voltages

ranging from 4.4V to 50V down to 2.0V to 24V for

VIN > VOUT.

The integrated high-side switch is used to chop or

modulate the input voltage using a controlled duty cycle

for output voltage regulation. High efficiency is

achieved by using a low-resistance switch, low forward

drop diode (Schottky diode), low Equivalent Series

Resistance (ESR) capacitors and low Direct Current

Resistance (DCR) inductor. When the switch is turned

on, a DC voltage is applied across the inductor (VIN –

VOUT), resulting in a positive linear ramp of inductor

current. When the switch turns off, the applied inductor

voltage is equal to -VOUT, resulting in a negative linear

ramp of inductor current (ignoring the forward drop of

the Schottky diode).

For steady-state, continuous inductor current opera-

tion, the positive inductor current ramp must equal the

negative current ramp in magnitude. While operating in

steady state, the switch duty cycle must be equal to the

relationship of VOUT/VIN for constant output voltage

regulation, under the condition that the inductor current

is continuous or never reaches zero. For discontinuous

inductor current operation, the steady-state duty cycle

will be less than VOUT/VIN to maintain voltage regula-

tion. The average of the chopped input voltage or SW

node voltage is equal to the output voltage, while the

average of the inductor current is equal to the output

current.

Schottky

Diode

COUT

CBOOST

Slope

Comp

PWM

Latch

–

Overtemp

Precharge

Comp

Amp

–

CCOMP

RCOMP

Drive

VREG

REF

VREF

Overtemperature

Boost

Precharge

Charge

500 kHz Osc

VOUT

RSENSE

GND

Boost

VIN

RTOP

RBOT

BOOST

GND

VREF

SHDN All Blocks

–

CIN

Note: EN has an internal pull-up, so the device will start even if the EN pin is left floating.

Diode

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