MP8042 – HIGH CURRENT, DUAL CHANNEL POWER HALF-BRIDGE

INITIAL RELEASE – SPECIFICATIONS SUBJECT TO CHANGE

MP8042 Rev. 0.9

www.MonolithicPower.com

7

5/23/2006

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TM

OPERATION

The MP8042 is a high voltage, dual channel

power half- bridge that can be configured as the

output of a Class D amplifier. The output is in

phase with the input, and the dead time is

optimized

for

symmetrical

performance,

regardless of load conditions.

causes both channels 1 and 2 to be shut off.

causes the outputs of both channels to go into

high impedance. However, when the voltage

across the BST1/2 and OUT1/2 pins drops

sufficiently low, the bottom MOSFET is turned

on to refresh the external bootstrap capacitor.

For a bootstrap capacitor of 100nF, the refresh

time is approximately 300µs.

In order to prevent erratic operation, two under

voltage lockout (UVLO) circuits are used. One

of them is to ensure that the supply for the

bottom gate drive circuit is sufficiently high and

the other is for the top gate driver.

Fault Protection

To protect the power MOSFETs, two layers of

protection are provided. The first is the current

limit, wherein if the current through either the

top or the bottom MOSFET exceeds an

internally preset value of 5A, that particular

MOSFET is immediately shut down and the

complementary MOSFET is turned on. If this

fails to reset the current and there is an

indication that the current is going to runaway,

the current foldback will kick in. This ensures

that the current is reset close to zero before

resuming operation.

Thermal monitoring is also integrated into the

MP8042. If the die temperature rises above

150

°C, both switches are turned off. The

temperature must fall below 140

°C before

normal operation resumes.

Fault Output

The MP8042 includes an open drain, active low

indicated if one of the following conditions is

detected: the current limit is tripped, the thermal

shutdown is tripped, the UVLO for the bottom

gate driver is tripped or the part is disabled.

be pulled low. However, only that fault channel

has its output set to high impedance.