Sharp SD-AT1000 (serv.man15) Service Manual ▷ View online
SD-AT1000
– 42 –
WAVEFORMS OF 1-BIT CIRCUIT
T
2
1
2.00V/div
500 ns/div
194.545465
µ
s
520 mV
2.00V/div
AD IC Output
+ Side
- Side
5 V
Amplitude
from 0 to 5 V
from 0 to 5 V
1
2
2
T
10.0 V/div
500 ns/div
194.545465
µ
s
-12.3 V
10.0 V/div
+ SIDE
+ FETOUT
- SIDE
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.
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.
2
1
11
12
12
2
1
2.00 V/div
500 ns/div
194.545465
µ
s
-12.30 V
2.00 V/div
AD IC NF IN
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.
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.
3
4
T
2.00 V/div
50.0 ns/div
0.0 s
-12.30 V
2.00 V/div
LEVEL SHIFT OUT
DEAD TIME
ZOOM UP
Dead time is generated by level
shift input.
Leading edge is delayed at CR,
passing R at DI.
Set value: 20 - 25 nsec.
shift input.
Leading edge is delayed at CR,
passing R at DI.
Set value: 20 - 25 nsec.
5
6
6
Display
