MP6903- FAST TURN-OFF INTELLIGENT CONTROLLER

MP6903 Rev. 1.04

www.MonolithicPower.com

7

1/31/2013

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FUNCTIONAL BLOCK DIAGRAM

Figure 1: Functional Block Diagram

OPERATION

The MP6903 supports operation in discontinuous

current mode (DCM), continuous current mode

(CCM), and critical conduction mode (CrCM)

condition. Operating in either a DCM or CrCM

condition, the control circuitry controls the gate in

forward mode and will turn the gate off when the

MOSFET current goes low. In CCM operation,

the control circuitry turns off the gate when very

fast transients occur.

Blanking

The control circuitry contains a blanking function.

When the MOSFET turns on or off, the blanking

function ensures that the previous state extends

for some minimum time period. The turn-on

blanking time is ~0.8µs. During the turn-on

blanking period, the turn-off threshold is not

totally blanked, but changes the threshold

voltage to approximately 100mV (instead of 0mV).

This assures that the part can always turn off

even during the turn-on blanking period. (The

synchronous period is recommended to be

greater than 0.8μs in CCM in the LLC Converter

to avoid shoot-through.)

VD Clamp

A high-voltage JFET is used at the input because

MOSFET.

Under-Voltage Lockout (UVLO)

part goes into sleep mode and a 10kΩ resistor

Enable pin

with a ~15uA current source. Leave this pin open

if unused.

When use external signal to control EN, it is

highly recommended the pull down current be

larger than 15uA to make sure the EN pin can be

pulled to low.