MP7770 –2 X 45W STEREO SE OR 90W MONO BTL CLASS D AUDIO AMPLIFIER

MP7770 Rev.1.0

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18

12/4/2012

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to the MP7770 while blocking the DC voltage.

Choose an input coupling capacitor such that

passband frequency. The corner frequency is

calculated as:

IN

IN

IN

C

R

2

1

f











Timer capacitor

The start-up source current slew rate is

value larger than 312nF, so the start-up current

slew rate would be smaller than 20mA/50ms

which helps eliminate the turn-on pop. The

a start-up current slew rate of approximately

20mA/350ms.

Power Source

For maximum output power, the amplifier circuit

requires a regulated external power source. A

high power-supply voltage can deliver more

power to a given load resistance, but a power-

source voltage exceeding the maximum voltage

of 36V can damage the MP7770. The

MP7770’s power supply rejection is excellent,

though power-supply noise can pass to the

output, so care must be taken to minimize

power supply noise within the pass-band

frequencies. Bypass the power supply with a

large capacitor (typically aluminum electrolytic)

along with a smaller 1μF ceramic capacitor at

PCB Layout

Circuit layout is critical for optimal performance,

low output distortion, and noise. Duplicate the

EVB layout for best results. For layout changes,

follow these guidelines and use Figure 8 as SE

layout references, use Figure 9 as BTL layout

reference.

1) Place the following components as close to

the MP7770 as possible:

Bootstrap Capacitors

BST1/2 pin and SW1/2 pin as possible.

SW2 pins as possible.

Power Supply Bypass Capacitors

the

switching

power

stage.

To

avoid

overstressing the MP7770 and excessive

pins and PGND1 pins as possible, and place

pins as possible.

Integral Capacitors

and are typically on the order of a few nF. Place

corresponding input as possible to reduce

as close to pins 2 and 3 as possible at SE

output configuration.

Reference Bypass Capacitors for SE Output

When used with SE output, CR1 and CR2 filter

power supply rejection and reduce distortion

and noise at the output.

2) The Inductor-Capacitor (LC) filter converts

the pulse train at SW to the output voltage that

drives the speaker. Please keep the filter

capacitor close to the inductor.

3) Keep the sensitive feedback signal trace on

the input side and shield the trace with the

AGND plane. Make sure that any traces

carrying the switch node (SW) voltages are

routed far from any input signal traces. If the

trace must run near the SW trace near the

input, shield the input with a ground plane

between the traces. Physically separate each

channel

to