MPQ2167 – 6V, 4A, FREQUENCY PROGRAMMABLE, BUCK CONVERTER, AEC-Q100 QUALIFIED

MPQ2167 Rev. 1.0

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19

3/21/2019

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not be on again until the inductor is lower than a

certain current threshold, which is called valley

current limit. The device will repeat this operation

until the short circuit disappears, and the output

returns to the regulation level. This protection

mode is very useful to prevent the inductor

current

from

running

away

and

possibly

damaging the components.

Over-Voltage Protection (OVP)

The MPQ2167 monitors the output voltage

through FB to detect output over-voltage

conditions. A VFB that exceeds 115% × VREF

(0.606V) triggers OVP, and the LS-FET turns on

to discharge VOUT until the inductor current drops

to zero while the HS-FET remains off. Then the

LS-FET will be shut off, and the output will be

discharged through the internal 100Ω resistor in

parallel to the LS-FET. The control will not begin

to switch until the output is within regulation.

Under Voltage Lock Out Protection (UVLO)

The MPQ2167 has input under voltage lock out

protection (UVLO) to ensure reliable output

power. Assuming EN is active, the MPQ2167 is

powered on when the input voltage is higher than

the UVLO rising threshold. It is powered off when

the input voltage drops below the UVLO falling

threshold. This function prevents the device from

operating at an insufficient voltage. It is a non-

latch protection.

Thermal Shutdown

The MPQ2167 has thermal protection by

monitoring the IC temperature internally. This

function prevents the chip from operating at an

exceedingly high temperature. If the junction

temperature

exceeds

the

threshold

value

(typically 170°C), it shuts down the whole chip.

This is a non-latch protection. There is a 25°C

hysteresis. Once the junction temperature drops

to about 145°C, the device resumes operation by

initiating a soft start.

Start-Up and Shutdown

If both VIN and VEN exceed their appropriate

thresholds, the chip starts up. The reference

block starts first, generating stable reference

voltage and currents, and then the internal

regulator is enabled. The regulator provides a

stable supply for the remaining circuitries.

While the internal supply rail is up, an internal

timer holds the power MOSFET OFF for about

50µs to blank the start-up glitches. When the

soft-start block is enabled, it first holds its SS

output low to ensure the rest of the circuitries are

ready, and then it slowly ramps up.

Three events can shut down the chip: EN low, VIN

UVLO, and thermal shutdown. In the shutdown

procedure, the signaling path is blocked first to

avoid any fault triggering. The COMP voltage and

the internal supply rail are then pulled down. The

floating driver is not subject to this shutdown

command, but its charging path is disabled.