Rolsen 21C19/PF21C19, Service Manual

Page: 27 / 46

SERVICE MANUAL
25
1.3 Sound power amplifier TDA7057AQ
2×8W Stereo BTL Audio Output Amplifier with DC Volume Control
1). Features
·
DC volume control
· Few external components
·
Mute mode
·
Thermal protection
·
Short-circuit proof
·
No switch-on and switch-off clicks
· Good overall stability
·
Low power consumption
·
Low HF radiation
·
ESD protected on all pins.
2). General Description
The TDA7057AQ is a stereo BTL output amplifier
with DC volume control. The device is designed for
use in TVs and monitiors, but is also suitable for
battery-fed portable recorders and radios.
Missing Current Limiter (MCL)
A MCL protection circuit is built-in. The MCL circuit is
activated when the difference in current between the
output terminal of each amplifier exceeds 100 mA
(typical 300 Ma). This level of 100 mA allows for
single-ended headphone applications.
3). Block Diagram
Fig.12