TM
MP8042 – HIGH CURRENT, DUAL CHANNEL POWER HALF-BRIDGE
INITIAL RELEASE – SPECIFICATIONS SUBJECT TO CHANGE
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.
The shutdown pin (
SHDN
), when set low,
causes both channels 1 and 2 to be shut off.
When the standby pin (
STBY
) is pulled low, it
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
fault indicator output (
FAULT
). A fault will be
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.
A fault on any channel causes the
FAULT
pin to
be pulled low. However, only that fault channel
has its output set to high impedance.
Do not apply more than 6V to the
FAULT
pin.
MP8042 Rev. 0.9
5/23/2006
www.MonolithicPower.com
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