MP7747 – 20W CLASS D MONO SINGLE ENDED AUDIO AMPLIFIER

MP7747 Rev. 1.0

www.MonolithicPower.com

9

1/28/2011

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Programmable UVP

MP7747 integrate programmable UVP function,

which can be used to shutdown the MP7747 to

escape the pop, by controlling the UVP node

voltage. The corresponding circuit is shown in

the followed figure 2. If the UVP pin is NC, the

default VDD UVP voltage (rising threshold) is

8.4V since there is internal voltage divided

circuit.

The VDD UVP voltage (rising threshold) can be

flexibly adjusted by controlling UVP pin voltage.

The recommended VDD shutdown voltage is

from 9.5V to power supply. As shown in the

figure 2, if external resistor RH and RL is low

enough (e.g. RH, RL < 50kΩ) compared with

internal 500kΩ and 550kΩ resistor, the VDD

shutdown voltage (rising threshold) can be

calculated by the equation:

HL

VDD _ shutdown

L

(R

R )

V4 *

R

+

=

The hysteresis voltage can be calculated by the

equation：

HL

hysteresis

L

RR

V0.3 *

R

+

=

VDD

UVP

AGND

+4V

+

-

MP7747

RH

RL

500k

Ω

550k

Ω

VDD

Figure 2—UVP Block Diagram