MCP16301HT-ESLASHCH datasheet(11/40 Pages) MICROCHIP

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DS20005004D-page 11

MCP16301/H

4.0

DETAILED DESCRIPTION

4.1

Device Overview

The MCP16301/H devices are high-input voltage

step-down regulators, capable of supplying 600 mA to

a regulated output voltage from 2.0V to 15V. Internally,

the trimmed 500 kHz oscillator provides a fixed

frequency, while the peak current mode control

architecture varies the duty cycle for output voltage

regulation. An internal floating driver is used to turn the

high-side integrated N-Channel MOSFET on and off.

The power for this driver is derived from an external

boost capacitor whose energy is supplied from a fixed

voltage ranging from 3.0V to 5.5V, typically the input or

output voltage of the converter. For applications with an

output voltage outside of this range, such as 12V, the

boost capacitor bias can be derived from the output

using a simple Zener diode regulator.

4.1.1

INTERNAL REFERENCE VOLTAGE

(VREF)

An integrated precise 0.8V reference combined with an

external resistor divider sets the desired converter

output voltage. The resistor divider range can vary

without affecting the control system gain. High-value

resistors consume less current, but are more

susceptible to noise.

4.1.2

INTERNAL COMPENSATION

All control system components necessary for stable

operation over the entire device operating range are

integrated, including the error amplifier and inductor

current slope compensation. To add the proper amount

of slope compensation, the inductor value changes

along with the output voltage (see Table 5-1).

4.1.3

EXTERNAL COMPONENTS

External components consist of:

• input capacitor

• output filter (inductor and capacitor)

• freewheeling diode

• boost capacitor

• boost blocking diode

• resistor divider.

The selection of the external inductor, output capacitor,

input capacitor and freewheeling diode is dependent

upon the output voltage and the maximum output

current.

4.1.4

ENABLE INPUT

Enable input, (EN), is used to enable and disable the

device. If disabled, the MCP16301/H devices consume

a minimal current from the input. Once enabled, the

internal soft start controls the output voltage rate of rise,

preventing high-inrush current and output voltage

overshoot.

4.1.5

SOFT START

The internal reference voltage rate of rise is controlled

during start-up, minimizing the output voltage over-

shoot and the inrush current.

4.1.6

UNDERVOLTAGE LOCKOUT

An integrated Undervoltage Lockout (UVLO) prevents

the converter from starting until the input voltage is high

enough for normal operation. The converter will typically

start at 3.5V and operate down to 3.0V. Hysteresis is

added to prevent starting and stopping during start-up,

as a result of loading the input voltage source.

4.1.7

OVERTEMPERATURE

PROTECTION

Overtemperature protection limits the silicon die

temperature to +150°C by turning the converter off. The

normal switching resumes at +120°C.

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