Datasheet

Philips Semiconductors
TDA8945S
15 W mono BTL audio amplifier
Product specification Rev. 02 — 7 April 2000 6 of 21
9397 750 06866
© Philips Electronics N.V. 2000. All rights reserved.
8.4 Supply Voltage Ripple Rejection (SVRR)
The SVRR is measured with an electrolytic capacitor of 10 µF on pin SVR at a
bandwidth of 10 Hz to 80 kHz. Figure 12 on page 11 illustrates the SVRR as function
of the frequency. A larger capacitor value on the SVR pin improves the ripple rejection
behaviour at the lower frequencies.
8.5 Built-in protection circuits
The TDA8945S contains two types of protection circuits, i.e. short-circuit and thermal
shutdown.
8.5.1 Short-circuit protection
Short-circuit to ground or supply line — This is detected by a so-called ‘missing
current’ detection circuit which measures the current in the positive supply line and
the current in the ground line. A difference between both currents larger than 0.7 A,
switches the power stage to standby mode (high impedance).
Short-circuit across the load — This is detected by an absolute-current
measurement. An absolute-current larger than 3 A, switches the power stage to
standby mode (high impedance).
8.5.2 Thermal shutdown protection
The junction temperature is measured by a temperature sensor; at a junction
temperature of approximately 150 °C this detection circuit switches the power stage
to standby mode (high impedance).
9. Limiting values
10. Thermal characteristics
Table 5: Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol Parameter Conditions Min Max Unit
V
CC
supply voltage no signal −0.3 +25 V
operating −0.3 +18 V
V
I
input voltage −0.3 V
CC
+ 0.3 V
I
ORM
repetitive peak output current - 2 A
T
stg
storage temperature non-operating −55 +150 °C
T
case
operating case temperature −40 +70 °C
P
tot
total power dissipation - 14 W
V
CC(sc)
supply voltage to guarantee
short-circuit protection
-18V
Table 6: Thermal characteristics
Symbol Parameter Conditions Value Unit
R
th(j-mb)
thermal resistance from junction to mounting base in free air 9 K/W