TFA9815 Datasheet, PDF (7/26 Pages) NXP Semiconductors – Stereo full-bridge audio amplifier 2 x 17 W

NXP Semiconductors
TFA9815
Audio amplifier 2 x 17 W
8.5 Protections
The TFA9815 has the following protections:
• OverTemperature Protection (OTP)
• OverCurrent Protection (OCP)
• OverVoltage Protection (OVP)
• UnderVoltage Protection (UVP)
• OverDissipation Protection (ODP)
• Window Protection (WP)
When either the OTP or the OCP are activated the output power stage is switched off and
all the outputs (OUT1N, OUT1P, OUT2N and OUT2P) become floating. The power stage
will switch back on after 5 µs or as soon as the fault condition is removed.
When any other protection is activated (OVP, UVP, ODP, or WP) all the outputs become
floating and the device shuts down. The TFA9815 will resume operating after the fault
condition has been removed, going through the restart sequence shown in Figure 3.
Restarting will typically take 500 ms, depending on the power-supply voltage level.
• Overtemperature protection
If the junction temperature (T_j) exceeds a threshold level of about 150 °C the outputs
become floating. The device will start switching again after 5 ms and when the
temperature is below 150 °C. This thermal limitation is without audible interruptions.
• Overcurrent protection
If the output current exceeds the maximum output-current threshold level the outputs
become floating. The device will start switching again after 5 µs. This current limitation
is without audible interruptions.
• Overvoltage protection
If the supply voltage applied to the TFA9815 exceeds the maximum supply-voltage
threshold level the device shuts down. The device will resume operating when the
supply is within the operating range, going through the restart sequence.
• Undervoltage protection
If the supply voltage applied to the TFA9815 falls below the minimum supply-voltage
threshold level the device shuts down. The device will resume operating when the
supply is within the operating range, going through the restart sequence.
• Overdissipation protection
If the junction temperature (T_j) exceeds 135 °C an internal OverTemperature Warning
(OTW) signal is generated. If the overcurrent protection is generated while the OTW is
active the device will shut down and resume operating automatically, going through
the restart sequence.
• Window protection
During start-up, if one of the outputs is shorted to V_SS or V_DD the device will interrupt
the start-up sequence and wait until the short is removed. This is an effective
measure to protect the device against shorts between the outputs (before the filter)
and the ground or supply lines. The WP protects the device against errors made
during board assembly.
TFA9815_1
Preliminary data sheet
Rev. 01 — 16 December 2008
© NXP B.V. 2008. All rights reserved.
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