Application Information High-Efficiency; Other Features; Turn On/Off Suggested Sequence; Single Signal St-By/Mute Control Circuit - Onkyo HTP-420 Service Manual

Figure 4: Turn ON/OFF Suggested Sequence
In addition to the overload protection described
above, the device features a thermal shutdown
circuit which initially puts the device into a muting
o
state (@ Tj = 150 C) and then into stand-by (@
o
Tj = 160 C).
Full protection against electrostatic discharges on
every pin is included.
Figure 5: Single Signal ST-BY/MUTE Control
Circuit
MUTE/
ST-BY
10K

3) Other Features

The device is provided with both stand-by and
+Vs
(V)
+40
-40
-Vs
V IN
(mV)
V ST-BY
5V
PIN #9
(V)
V MUTE 5V
PIN #10
(V)
I Q
(mA)
V OUT
(V)
OFF
ST-BY
MUTE
MUTE STBY
20K
30K
10µF 10µF
1N4148
D93AU014
PLAY ST-BY
MUTE
mute functions, independently driven by two
CMOS logic compatible input pins.
The circuits dedicated to the switching on and off
of the amplifier have been carefully optimized to
avoid any kind of uncontrolled audible transient at
the output.
The sequence that we recommend during the
ON/OFF transients is shown by Figure 4.
The application of figure 5 shows the possibility of
using only one command for both st-by and mute
functions. On both the pins, the maximum appli-
cable range corresponds to the operating supply
voltage.
APPLICATION INFORMATION
HIGH-EFFICIENCY
Constraints of implementing high power solutions
are the power dissipation and the size of the
power supply. These are both due to the low effi-
ciency of conventional AB class amplifier ap-
proaches.
Here below (figure 6) is described a circuit pro-
posal for a high efficiency amplifier which can be
adopted for both HI-FI and CAR-RADIO applica-
tions.
OFF
D98AU817
TDA7293
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