MP3427 – 17A, 600kHz, 8V WIDE INPUT RANGE SYNCHRONOUS BOOST CONVERTER IN A SMALL 3X4MM QFN PACKAGE

MP3427 Rev. 1.0

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12/26/2014

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current. This causes the MP3427 to enter

hiccup mode (after 1.1ms). MP3427 re-starts

after 60ms in hiccup mode. If the sampled

current signal rises to 100mV (within the 1.1ms

blank time), MP3427 operates in hiccup mode

immediately.

MP3427 starts switching in internal current-

sense mode after it detects 0V on MODE. In

external current-sense mode, MP3427 detects

MODE voltage and starts switching (after

or hiccup mode, MODE is pulled low. If the

average current limit is triggered before

switching, the MP3427 may not start switching

because MODE is regulated low in an overload

condition.

If the peak-inductor current is higher than 6A,

an

external

current-sensing

resistor

is

recommended. Do NOT change the sensing

configuration when MP3427 is in operation.

Light-Load Operation

To optimize efficiency at light load, MP3427

employs a pulse-skipping mechanism and

foldback frequency. When the load becomes

lighter, the COMP voltage decreases, causing

the MP3427 to enter foldback operation (the

higher the load, the lower the frequency).

However, if the load becomes exceedingly low,

the MP3427 enters PSM. PSM operation is

optimized so that only one SW pulse is

launched every burst cycle. Therefore the

output ripple is very low.

Enable and Programmable UVLO

EN enables and disables the device. When

applying voltage higher than the EN higher

threshold (1V, typically), MP3427 starts up

some of the internal circuits (micro-power

mode). If EN voltage exceeds the turn-on

threshold

(1.33V),

MP3427

enables

all

functions and starts boost operation. Boost

operation turns off if EN voltage falls below the

1.33V threshold. To shut down the device, the

<0.4V low-level voltage is required on EN. After

being shut down, MP3427 sinks a current from

input power (less than 1uA, typically).

The maximum recommended voltage on EN is

5.5V. If the EN control signal comes from a

voltage higher than 5.5V, a resistor should be

added between EN and the control source, An

internal Zener diode on EN clamps the EN

voltage to prevent runaway. Ensure the Zener

clamped current flowing into EN is less than

0.3mA.

Meanwhile, EN programs Vin’s UVLO (see

“Applications\UVLO Hysteresis” section).

Thermal Shutdown (TSD)

Tp prevent thermal damage, the device has an

internal

temperature

monitor.

If

the

die

temperature exceeds 150°C, the converter

turns off. Once the temperature drops below

125°C, the power supply resumes operation.

.