MCP16301HT-ESLASHCH datasheet(12/40 Pages) MICROCHIP

12 / 40 page

MCP16301/H

DS20005004D-page 12

 2011-2015 Microchip Technology Inc.

FIGURE 4-1:

MCP16301/H Block Diagram.

4.2

Functional Description

4.2.1

STEP-DOWN OR BUCK

CONVERTER

The MCP16301/H devices are non-synchronous

step-down or buck converters, capable of stepping

input voltages ranging from 4V to 30V (MCP16301) or

36V (MCP16301H) down to 2.0V to 15V 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, low equivalent series resistance (ESR), an

inductor and a capacitor. When the switch is turned on,

a DC voltage is applied to 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

operation, 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 regulation. 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.

FIGURE 4-2:

Step-Down Converter.

Schottky

Diode

COUT

CBOOST

Slope

Comp

PWM

Latch

Overtemp

Precharge

Comp

Amp

CCOMP

RCOMP

Drive

VREG

REF

VREF

OTEMP

Boost

Pre-

charge

500 kHz OSC

VOUT

RSENSE

GND

Boost Diode

VIN

RTOP

RBOT

BOOST

GND

VREF

SHDN all blocks

CIN

Schottky

Diode

COUT

VOUT

VIN

off

IOUT

VOUT

VIN

off

IOUT

VIN

Continuous Inductor Current Mode

Discontinuous Inductor Current Mode

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