Waveforms Of 1-Bit Circuit - Sharp SD-SH111H Service Manual

2.00V/div 2.00V/div
AD IC Output
1
2
500ns/div
Amplitude
from 0 to 5 V
2.00V/div 2.00V/div
3
AD IC NF IN
4
500ns/div

WAVEFORMS OF 1-BIT CIRCUIT

+ Side
5V
- Side
194.545465µs 520mV
194.545465µs -12.30V
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.
2.00V/div
LEVEL SHIFT OUT
5
T
2
6
1
ZOOM UP
10.0V/div
+FETOUT
2
11
12
1
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 HI GH side shows that only the
booted voltage lowers.
– 87 –
SD-SH111H
2.00V/div
DEAD TIME
50.0ns/div 0.0s
Dead time is generated by level
shift input.
Leading edge is delayed at CR,
passing R at DI.
Set value: 20 -25 nsec
10.0V/div
+SIDE
- SIDE
500ns/div 194.545465µs
T
-12.30V
2
T
1
-12.3V