tfa9842j-n1 NXP Semiconductors, tfa9842j-n1 Datasheet - Page 6

• Manufacturer Part Number: tfa9842j-n1
• Description: 2-channel Audio Amplifier; Se 1 W To 7.5 W; Btl 2 W To 15 W
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 12013
Preliminary data
8.4 Supply voltage ripple rejection
8.5 Built-in protection circuits
Standby — The current consumption is very low and the outputs are floating. The
device is in standby mode when V
Mute — The amplifier is DC-biased but not operational (no audio output). This allows
the input coupling capacitors to be charged to avoid pop-noise. The device is in mute
mode when 4.5 V < V
On — The amplifier is operating normally. The operating mode is activated at
V
The supply voltage ripple rejection (SVRR) is measured with an electrolytic capacitor
of 150 F on pin SVR using a bandwidth of 20 Hz to 22 kHz.
SVRR as function of the frequency. A larger capacitor value on pin SVR improves the
ripple rejection behavior at the lower frequencies.
The TFA9842J contains two types of temperature sensors; one measures local
temperatures of the power stages and one measures the global chip temperature. At
a local temperature of the power stage of approximately 185
temperature of approximately 150
stages for 2 ms. High impedance of the outputs is the result. After this time period the
power stages switch on automatically and the detection will take place again; still a
too high temperature switches off the power stages immediately. This protects the
TFA9842J against shorts 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 be flowing through the short,
just as much as the power stage can handle without exceeding the critical
temperature level.
Fig 3. Mode selection.
MODE
> (V
CC
standby
2.0 V).
Rev. 01 — 26 April 2004
0.8
MODE
4.5
< (V
CC
MODE
o
C this detection circuit switches off the power
3.5 V).
2-channel audio amplifier (2 x SE or 1 x BTL)
all mute
< 0.8 V, or when pin MODE is grounded.
V CC 3.5
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
V CC 2.0
1/2 on
Figure 11
o
V MODE (V)
C or a global
TFA9842J
V CC
MCE502
illustrates the
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