Table of Contents
Advertisement
Philips Semiconductors
8.5 Built-in protection circuits
9. Limiting values
10. Thermal characteristics
TFA9843AJ_1
Preliminary data sheet
The TFA9843AJ contains two types of temperature sensors; one measures the local
temperatures of the power stages and one measures the global chip temperature. At a
local temperature of the power stage of approximately 185 C or a global temperature of
approximately 150 C this detection circuit switches off the power stages for 2 ms. When
the outputs are switched off the voltage is measured on the outputs. In the event of a
short-circuit to ground or to V
cases the power stages switch-on automatically and the detection will take place again;
however a too high temperature will switch-off the power stages immediately. This can
result in repetitive switching during too high junction temperature. This protects the
TFA9843AJ against short-circuits to ground, to the supply voltage, across the load and too
high chip temperatures.
The protection will only be activated when necessary, so even during a short-circuit
condition, a certain amount of (pulsed) current will still flow through the short-circuit (as
much as the power stage can handle without exceeding the critical temperature level).
Table 6.
Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134).
Symbol
Parameter
V
supply voltage
CC
V
input voltage
I
I
repetitive peak output current
ORM
T
storage temperature
stg
T
ambient temperature
amb
P
total power dissipation
tot
V
short-circuit protection supply
CC(scp)
voltage
Table 7.
Thermal characteristics
Symbol
Parameter
R
thermal resistance from
th(j-a)
junction to ambient
R
thermal resistance from
th(j-c)
junction to case
20 W stereo power amplifier with volume control
the device will remain in Protection mode. In all other
CC
Conditions
operating
non-operating
operating
Conditions
in free air
both channels
driven
Rev. 01 — 28 April 2006
TFA9843AJ
Min
Max
0.3
+28
0.3
V
+ 0.3
CC
-
4
55
+150
40
+85
-
35
-
26
Value
Unit
40
K/W
2.0
K/W
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Unit
V
V
A
C
C
W
V
6 of 19
Advertisement
Table of Contents
