MP8040 – HIGH CURRENT INTEGRATED HALF BRIDGE + DRIVER

MP8040 Rev. 1.5

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5

5/3/2005

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TM

SW Output

The SW output drives the load. It is controlled

by the logic input signal at PWM. When the

signal at PWM is high (above 2V), the high-side

switch is turned on. When the signal at PWM is

low (less than 0.4V), the low-side switch is

turned on.

The

MP8040

uses

internal

N-Channel

MOSFETs for both the high-side and low-side

switches. The high-side MOSFET gate drive is

powered from the voltage between SW and BS,

allowing BS to rise above the SP input voltage

to power the high-side MOSFET. To do this a

bootstrap capacitor is connected between SW

and BS. When the low-side switch is on, the

capacitor is internally charged from the voltage

at DRV, which is also internally generated.

There is a dead time region (typically 40ns)

where both the upper and lower switches are

off (see Figure 2).

Both the high-side and low-side switches have

internal current limits to prevent failure due to

excessive load current. Once the current limit is

reached, both output switches are turned off

and the fault output is asserted (driven low).

Shutdown

The MP8040 includes a 2.5µA shutdown mode.

When SHDN is high, both output switches are

turned off and the input current drops to 2.5µA.

When the MP8040 is shutdown, the internally

generated voltage at DRV drops to 0V, and the

fault output (FLT) is asserted (driven low). If the

shutdown mode is not used, connect SHDN

directly to GND.

Fault Output

The MP8040 includes a fault indicator output

(FLT). This is an active-low open drain output.

The MP8040 detects faults due to over-current

(>9A),

over-temperature

(>160°C),

under-

voltage at SP (<6.5V), or if the part is disabled.

Connect FLT to DRV or to an external voltage

up to 6V through a 27kΩ or greater resistor.

When any of the 3 fault conditions are detected,

both output switches are turned off and the SW

output is high-impedance.

Thermal Shutdown

The MP8040 includes a thermal overload

protection circuit. If the die temperature rises

above 160°C, the output switches are turned off

and the fault output is asserted. Once the

thermal overload circuit is tripped, the die

temperature must drop below 140°C before

automatically restarting.

TIME

SW

DT (RISE)

DT (FALL)

DEAD TIME RISING = 20ns

DEAD TIME FALLING = 40ns

MP8040_F01

MP8040

SP

GND

2

4

3

SW

Figure 2—Dead Time