MPQ2451-5/33―36V, 2.2MHz, 0.6A, STEP-DOWN CONVERTER, AEC-Q100 QUALIFIED

MPQ2451-5/33 Rev 1.0

www.MonolithicPower.com

11

5/25/2016

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© 2016 MPS. All Rights Reserved.

OPERATION

The MPQ2451-5/33 is a 2.2MHz, asynchronous,

step-down, switching regulator with an integrated

high-side,

high-voltage,

power

MOSFET.

It

provides

an

internally-compensated,

highly-

efficient output of up to 0.6A with current-mode

control. It also features a wide input voltage

range, internal soft-start control, and a precise

current limit. Its very-low, operational, quiescent

current makes it suitable for battery-powered

applications.

PWM Control

At

moderate-to-high

output

current,

the

MPQ2451-5/33 operates in a fixed-frequency,

peak-current-control mode to regulate the output

voltage. A PWM cycle

—initiated by the internal

clock

—turns the power MOSFET on, and the

MOSFET remains on until its current reaches the

low, the power switch turns off and remains off

for at least 100ns before the next cycle starts.

If the current in the power MOSFET does not

reach the COMP-set current value within one

PWM cycle, the power MOSFET remains ON to

avoid a turn-off operation.

Pulse-Skipping Mode

Under light-load conditions, the MPQ2451-5/33

enters pulse-skipping mode to improve efficiency.

the internal sleep threshold, which generates a

PAUSE command to block the turn-on clock

pulse so the power MOSFET does not turn ON;

this

procedure

reduces

gate

driving

and

switching losses. This PAUSE command causes

the whole chip to enter sleep mode, reducing the

quiescent current to further improve light-load

efficiency.

PAUSE signal resets and the chip resumes

normal PWM operation. Whenever the PAUSE

changes state from LOW to HIGH, the PWM

signal immediately goes HIGH and turns on the

power MOSFET.

Error Amplifier

The error amplifier is composed of an internal op-

amp with an RC feedback network connected

between its output node (COMP) and its negative

drives the COMP output high, driving the switch

peak current to rise and deliver more energy to

Internal Regulator

The 2.6V internal regulator powers most of the

exceeds 3.0V, the output of the regulator is in full

output degrades.

Enable Control

The MPQ2451-5/33 has a dedicated enable

the EN pin can enable or disable the chip for

HIGH effective logic. Its falling threshold is 1.2V,

and its rising threshold is about 1.6V. When left

floating, the EN pin is internally pulled down to

GND to disable the chip.

When the EN voltage is pulled to 0V, the chip

enters

the

lowest

shutdown

current

mode.

Between 0V and the rising threshold, the chip

remains in shutdown mode with a slightly higher

shutdown current.

Under-Voltage Lockout (UVLO)

chip from operating at an insufficient supply

voltage. The UVLO rising threshold is ~2.9V

while its falling threshold is 2.6V.

Internal Soft-Start

A reference-type soft-start (SS) prevents the

converter-output

voltage

from

overshooting

during startup. When the chip starts, the internal

amplifier reference.

accommodates short-circuit recovery; when the

output-voltage overshoot.