MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE

MP3421 Rev. 1.0

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12

11/13/2014

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are recommended for good stability and

transient balance.

Current Sensing

Lossless-current sensing converts the NMOS

switch current signal to voltage, which is

summed with the internal slope compensation.

The summed signal is compared to the error

amplifier output to provide a peak-current

control command for the PWM. The minimum

peak-switch current limit is 5.5A. Internally, the

switch-current signal is blanked for about 60ns

to enhance noise rejection.

Output Disconnect

The MP3421 has true output disconnect by

eliminating body diode conduction from the

to 0V during shutdown or isolate and maintain

inrush-current limit at startup, minimizing surge

current from the input supply. To efficiently

utilize output disconnect, eliminate (if necessary)

the external Schottky diode connection between

Over-Load (OLP)and Short-Circuit (SCP)

Protection

If an overload or short circuit occurs, the output

drops below 1.7V, the device enters linear

nominal

output

voltage,

the

MP3421

immediately shuts down and re-starts in a

power-on cycle after 40μs.

Over-Voltage Protection (OVP)

This prevents overvoltage from damaging the

internal power MOSFET.

When the output

drops below 7V, the device resumes switching

automatically.

Thermal Shutdown (TSD)

The device contains an internal temperature

monitor.

The switches turn off if the die

temperature exceeds 150°C.

The device

resumes

normal

operation

below

130°C.