Datasheet

TAS5624A
SLAS844 –MAY 2012 www.ti.com
DEVICE PROTECTION SYSTEM
The TAS5624A contains advanced protection circuitry carefully designed to facilitate system integration and ease
of use, as well as to safeguard the device from permanent failure due to a wide range of fault conditions such as
short circuits, overload, overtemperature, and undervoltage. The TAS5624A responds to a fault by immediately
setting the power stage in a high-impedance (Hi-Z) state and asserting the FAULT pin low. In situations other
than overload and overtemperature error (OTE), the device automatically recovers when the fault condition has
been removed, i.e., the supply voltage has increased.
The device will function on errors, as shown in the following table.
Table 3. Device Protection
BTL Mode PBTL Mode SE Mode
Channel Fault Turns Off Channel Fault Turns Off Channel Fault Turns Off
A A+B A A+B+C+D A A+B
B B B
C C+D C C C+D
D D D
Bootstrap UVP does not shutdown according to the table, it shuts down the respective high-side FET.
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PIN-TO-PIN SHORT CIRCUIT PROTECTION (PPSC)
The PPSC detection system protects the device from permanent damage if a power output pin (OUT_X) is
shorted to GND or PVDD_X. For comparison, the OC protection system detects an over current after the
demodulation filter where PPSC detects shorts directly at the pin before the filter. PPSC detection is performed at
startup i.e. when VDD is supplied, consequently a short to either GND or PVDD_X after system startup will not
activate the PPSC detection system. When PPSC detection is activated by a short on the output, all half bridges
are kept in a Hi-Z state until the short is removed, the device then continues the startup sequence and starts
switching. The detection is controlled globally by a two step sequence. The first step ensures that there are no
shorts from OUT_X to GND, the second step tests that there are no shorts from OUT_X to PVDD_X. The total
duration of this process is roughly proportional to the capacitance of the output LC filter. The typical duration is
<15 ms/μF. While the PPSC detection is in progress, FAULT is kept low, and the device will not react to changes
applied to the RESET pins. If no shorts are present the PPSC detection passes, and FAULT is released. A
device reset will not start a new PPSC detection. PPSC detection is enabled in BTL and PBTL output
configurations, the detection is not performed in SE mode. To make sure not to trip the PPSC detection system it
is recommended not to insert resistive load to GND or PVDD_X.
OVERTEMPERATURE PROTECTION
The TAS5624A has a two-level temperature-protection system that asserts an active-low warning signal (OTW)
when the device junction temperature exceeds 125°C (typical). If the device junction temperature exceeds 155°C
(typical), the device is put into thermal shutdown, resulting in all half-bridge outputs being set in the high-
impedance (Hi-Z) state and FAULT being asserted low. OTE is latched in this case. To clear the OTE latch,
RESET must be asserted. Thereafter, the device resumes normal operation.
OVERTEMPERATURE WARNING, OTW
The over temperature warning OTW asserts when the junction temperature has exceeded recommended
operating temperature. Operation at junction temperatures above OTW threshold is exceeding recommended
operation conditions and is strongly advised to avoid.
If OTW asserts, action should be taken to reduce power dissipation to allow junction temperature to decrease
until it gets below the OTW hysteresis threshold. This action can be decreasing audio volume or turning on a
system cooling fan.
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