TFA9881_1104 PHILIPS [NXP Semiconductors], TFA9881_1104 Datasheet - Page 12

• Manufacturer Part Number: TFA9881_1104
• Description: 3.4 W PDM input class-D audio amplifier
• Manufacturer: PHILIPS [NXP Semiconductors]

NXP Semiconductors
TFA9881
Product data sheet
8.6.3 Supply voltage protection mechanisms (UVP and OVP)
8.6.4 OverCurrent Protection (OCP)
UVP is activated, setting the outputs floating, if V
protection threshold, V
supply voltage rises above V
f
OVP is activated, setting the power stages floating, if the supply voltage rises above the
overvoltage protection threshold, V
supply voltage drops below V
f
Note that a supply voltage > 5.5 V may damage the TFA9881.
OCP will detect a short circuit across the load or between one of the amplifier outputs and
one of the supply lines. If the output current exceeds the overcurrent protection threshold
(I
not powered down completely). This is called current limiting. The amplifier can
distinguish between an impedance drop at the loudspeaker and a low-ohmic short circuit
across the load or to one of the supply lines. The impedance threshold depends on which
supply voltage is being used:
clk
clk
O(ocp)
•
•
= 6.144 MHz.
= 6.144 MHz.
In the event of a short circuit across the load or a short to one of the supply lines, the
audio amplifier is switched off completely. It will try to restart again after approximately
100 ms with f
time, this cycle will be repeated. Average dissipation will be low because of the short
duty cycle.
In the event of an impedance drop (e.g. due to dynamic behavior of the loudspeaker),
the same protection mechanism will be activated. The maximum output current is
again limited to I
audio holes from occurring). This will result in a clipped output signal without artifacts.
), it will be limited to I
All information provided in this document is subject to legal disclaimers.
clk
= 6.144 MHz. If the short-circuit condition is still present after this
O(ocp)
P(uvp)
Rev. 2 — 1 April 2011
, but the amplifier will not switch off completely (thus preventing
O(ocp)
. This transition will be silent, without pop noise. When the
P(uvp)
P(ovp)
while the amplifier outputs are switching (the amplifier is
again, the system will be restarted after 100 ms with
P(ovp)
again. The system will be restarted after 100 ms with
. The power stages are re-enabled as soon as the
3.4 W PDM input class-D audio amplifier
DDP
drops below the undervoltage
TFA9881
© NXP B.V. 2011. All rights reserved.
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