MP7758

– 18V, 2x15W, STEREO BTL, INDUCTORLESS CLASS-D AUDIO AMPLIFIER

MP7758 Rev. 1.0

www.MonolithicPower.com

16

12/3/2020

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Gain Setting

The MP7758

’s gain is set by the input terminals

GAIN0 and GAIN1. The actual gain settings are

controlled by the ratios of the internal input and

feedback resistors (see Table 2).

Table 2: Gain Setting

GAIN0 GAIN1

Typical

Gain (dB)

Typical Input

Impedance (k

Ω)

0

0

20

75

1

0

26

50

0

1

32

30

1

1

36

20

Over-Temperature Shutdown

The MP7758 monitors the temperature. If the

die temperature rises above 150°C, all switches

turn off. The temperature must fall below 130°C

before normal operation resumes. The device

uses the same start-up sequence to prevent

popping noise.

Short-Circuit Protection (SCP)

The MP7758 has internal overload and short-

circuit protection (SCP). The currents in both

the high-side and low-side MOSFETs are

measured. If a short circuit is detected, all

MOSFETs of the full bride that detected the

over-current condition go into high impedance

for a fixed duration before resuming normal

operation. If the short circuit condition is

removed after the fixed duration, the MP7758

restarts. The device uses the same start-up

sequence to prevent popping noise.

Fault Output

The MP7758 includes an open drain, active low

fault indicator output on the /FAULT pin. A fault

triggers if either the current limit or thermal

shutdown threshold is tripped.

A fault on any channel causes the /FAULT pin

to pull low. A fault on either channel causes the

all outputs to go into high impedance. When the

fault

condition

is

removed,

the

MP7758

resumes normal operation (see Figure 5).

Normal Operation

Over-current

condition

detected?

No

Disable output,

/FAULT = low

Yes

Enable output,

/FAULT = high

Yes

TEMP >

150°C?

No

Disable output,

/FAULT = low

Yes

TEMP <

130°C?

No

Yes

Enable output,

/FAULT = high

100µs timeout

finished?

No

Figure 5: Fault Timing Chart