MP8049S - 24V, 5.5A QUAD CHANNEL POWER HALF-BRIDGE

MP8049S Rev. 1.01

www.MonolithicPower.com

10

10/24/2018

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OPERATION

The MP8049S is a quad channel power half-

bridge driver 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.

When the shutdown (SHDN) pin is low, all

channels will be off. When the standby (STBYB)

is pulled low, it causes the outputs of all channels

to go into high impedance. However, when the

voltage

across

the

BST1A/1B/2A/2B

and

SW1A/1B/2A/2B pins drops sufficiently low, the

bottom MOSFET will be turned on to refresh the

external bootstrap capacitor. Suggest connect a

0.1μF or greater capacitor between BST and SW

pins as the bootstrap capacitor.

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, an internal

current limit of 5.5A is set for all MOSFETs.

When this limit is reached, all four MOSFETs of

the over current full bridge channel will go into

high

impedance

for

a

fixed

duration

of

approximately 30us before resuming normal

operation.

Thermal monitoring is also integrated into the

MP8049S. If the die temperature rises above

160ºC, all

switches are

turned off. The

temperature must fall below 125ºC before normal

operation resumes.

To enhance the robustness of the device under

short circuit condition, a capacitor can be

connected to the FaultB pin, as shown in figure 1.

The time constant of the RC is selected to be

greater than 50ms for the FaultB node to reach

2V. Under short circuit condition, the FaultB node

will be reset to zero and the part will be place in

standby mode until the voltage at the STBYB pin

is above 2V.

FAULTB

STBYB

R

C

MP8049S

5V

Figure 1—Fault Protection Enhancement

Circuit

Fault Output

The MP8049S includes an open drain, active low

fault indicator output (FAULTB). A fault will be

indicated if one of the following conditions is

detected: the current limit is tripped, or the

thermal shutdown is tripped.

A fault on any channel will cause the FAULTB pin

to be pulled low. When the fault goes away, the

MP8049S will resume normal operation.

Do not apply more than 6V to the FAULTB pin.

Error Reporting

The MP8049S also have two fault monitor pins

(FLT3B and FLT2B), which are active low and

open-drain

outputs.

Their

function

is

for

protection-mode signaling to a PWM controller or

other system control device, as shown in the

below table.

OCP

OTP

UVP

FLTB2

FLTB3

0

0

0

1

1

0

0

1

0

1

0

1

0

1

0

1

0

0

0

0

Table 1- Fault Boolean