MPM3530

– 55V, 3A, STEP-DOWN POWER MODULE

MPM3530 Rev. 1.0

www.MonolithicPower.com

11

9/21/2018

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© 2018 MPS. All Rights Reserved.

OPERATION

The MPM3530 is a high-performance and

complete power solution that features a wide

input

voltage

range,

high

efficiency,

external/internal

soft

start,

programmable

frequency,

and

comprehensive

protection

modes (OVP, OCP, OTP).

Pulse-Width Modulation (PWM) Control

The MPM3530 uses peak-current-mode control

to regulate the output voltage. A pulse-width

modulation (PWM) cycle is initiated by the

internal clock at the beginning of every cycle.

After the high-side MOSFET (HS-FET) turns on,

the inductor current rises linearly to provide

energy to the load. The HS-FET remains on

until its current reaches the COMP voltage

amplifier (EA). The output voltage of the error

amplifier depends on the difference of the

output feedback voltage and the internal high-

precision reference, and it decides how much

energy should be transferred to the load. The

After the high-side switch turns off, the low-side

switch turns on, and the inductor current flows

through the low-side switch. To avoid a shoot-

through issue, a dead time is inserted to

prevent the HS-FET and LS-FET from turning

on at the same time. For each turn-on and turn-

off in a switching cycle, the HS-FET turns on

and off with a minimum on and off time limit.

Light-Load Operation

To achieve high efficiency, the MPM3530 uses

two features during light load.

First, when the load current decreases, the

inductor current drops at the same time. The

LS-FET turns off to save driver loss when the

inductor current drops to zero.

Second,

when

the

load

decreases,

the

switching frequency is scaled down to reduce

below a certain threshold.

Error Amplifier (EA)

The error amplifier compares the FB voltage

current proportional to the difference between

the two. This current is used to charge the

which is used to control the HS-FET peak

current and regulate the output voltage.

Oscillator and SYNC Function

The internal oscillator frequency is set by the

frequency

set

resistor

connected

between FREQ and GND. The relationship

shown in Table 1 on page 14.

During light load, the switching frequency is

lower

than

about

0.8V. The switching

is

Reduce switching loss and thermal dissipation,

the switching frequency is decreased according

switching frequency starts decreasing from the

normal value and finally drops to 5% of the

normal value when FB is zero.

FREQ can be used to synchronize the internal

oscillator rising edge to an external clock falling

edge. Ensure that the high amplitude of the

SYNC clock is higher than 1.5V and the low

amplitude is lower than 1V to drive the internal

logic.

The

recommended

external

SYNC

frequency is in the range of 100kHz to 1MHz.

There is no pulse-width requirement but note

that there is always a parasitic capacitance of

the pad. If the pulse width is too short, a clear

rising and falling edge may not be seen due to

the parasitic capacitance. A pulse longer than

100ns is recommended in the application.

Enable Control (EN)

EN is a control pin that turns the module on and

off. Drive EN above 1.6V to turn on the

regulator. Drive EN below 1.3V to turn off the

regulator.