Circuit Descriptions, Abbreviation List, and IC Data Sheets
EN 109
EJ2.0U LA
9.
9.2.2
Over-Current Protection
If an over current error occurs (short-circuit on the output),
transistors 7D30 and 7D12-1 will conduct and 7D12-2, 7D26-2
and 7D26-1 will block. This causes the MUTE output to be
“high”. See figure “Over-current protection and sound mute” for
details. The arrows indicate the signal levels during over-
current protection active.
Figure 9-7 Over-current protection and sound mute
During start-up, diode 6D11 is blocked causing transistors
7D12, 7D26-2 and 7D26-1 to be blocked. MUTE is then “high”.
This prevents an audio plop during start-up. When supply is at
normal level, diode 6D11 will conduct causing transistors
7D12-2, 7D26-2 and 7D26-1 to conduct as well. A sound mute
is then depending on the signal on the SOUND_ENABLE line:
“high” causes a sound mute (MUTE is “high”) and “low” causes
sound enabled (MUTE is “low”).
Over Current Prot Mute
Under-volt supply
protection (18V)
If mute 2V to 4V
In play mode = 0V
Amplifier output
H
H
H
L
L
OVER-CURRENT PROTECTION
SIGNAL LEVELS
G_15940_066.eps
260506
3D82
2D51
1n
3D83
47k
3D26
2k2
3D24
10k
3D25
47k
3D85
47k
3D84
47k
3D42
47k
3D87
47k
3D88
33k
3D23
2k2
3D86
47k
3D77
22k
3D60
0R1
3D75
47k
6D11
7D25-2
7D26-2
7D30
7D26-1
7D12-1
7D25-1
- MUTE ACTIVE: 2V TO 4V
- MUTE NOT ACTIVE: 0V (PLAY MODE)
“HIGH’: SOUND DIS ABLED
”LOW”: SOUND ENABLED
7D12-2
47k
