SHARP SD-AT1000H
Service Manual

SD-AT1000H

WAVEFORMS OF 1-BIT CIRCUIT
2.00V/div AD IC Output 2.00V/div + Side
2.00 V/div 2.00 V/div LEVEL SHIFT OUT
T

1 2
5V

T

2

5 6

DEAD TIME

1

- Side 500 ns/div Amplitude from 0 to 5 V 194.545465 µs 520 mV
50.0 ns/div 0.0 s -12.30 V Dead time is generated by level shift input. Leading edge is delayed at CR, passing R at DI. Set value: 20 - 25 nsec.

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2.00 V/div

2.00 V/div

10.0 V/div

10.0 V/div

3
2

+ FETOUT + SIDE
2

11
AD IC NF IN

T

12
1

- SIDE

1

4
500 ns/div 194.545465 µs -12.30 V
500 ns/div Waveforms before low-pass filters at both ends of the speaker. H-bridge may be considered as BTL. However, here and at the gate drive, dead time is not observed; since bootstrap operates based on output, DEAD TIME part is in floating condition. The waveform on the HIGH side shows that only the booted voltage lowers. 194.545465 µs -12.3 V

In partial pressure OUT, 4 to 7 V amplitude of GND reference is observed. In IC of 75 kohms, the reference is 2.5 V because of VREF. Due to imaginary GND of operational amplifier inside IC, the waveform cannot be monitored. This waveform is partial pressure OUT.

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