Datasheet

TAS5631B
www.ti.com SLES263C –NOVEMBER 2010–REVISED SEPTEMBER 2012
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_X or PVDD_X. For comparison, the OC protection system detects an overcurrent after the
demodulation filter, whereas 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_X or PVDD_X after
system startup does 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 start-
up 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_X; 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, SD is kept low, and the device
does not react to changes applied to the RESET pin. If no shorts are present, the PPSC detection passes, and
SD is released. A device reset does 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 between OUT_X and GND_X or PVDD_X.
OVERTEMPERATURE PROTECTION
The two different package options have individual overtemperature protection schemes.
PHD Package
The TAS5631B PHD package option has a three-level temperature-protection system that asserts an active-low
warning signal (OTW1) when the device junction temperature exceeds 100°C (typical), (OTW2) when the device
junction temperature exceeds 125°C (typical) and, 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 SD being asserted low. OTE is latched in this case. To clear the OTE latch, RESET must be asserted.
Thereafter, the device resumes normal operation. For highest reliability, the RESET should not be asserted until
OTW1 has cleared.
DKD Package
The TAS5631B DKD package option has a two-level temperature-protection system that asserts an active-low
warning signal (OTW) when the device junction temperature exceeds 125°C (typical) and, 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 SD being asserted low. OTE is latched in this case. To clear the
OTE latch, RESET must be asserted. It is recommended to wait until OTW has cleared before asserting RESET.
Thereafter, the device resumes normal operation.
UNDERVOLTAGE PROTECTION (UVP) AND POWER-ON RESET (POR)
The UVP and POR circuits of the TAS5631B fully protect the device in any power-up/down and brownout
situation. While powering up, the POR circuit resets the overload circuit (OLP) and ensures that all circuits are
fully operational when the GVDD_X and VDD supply voltages reach values stated in the Electrical
Characteristics table. Although GVDD_X and VDD are independently monitored, a supply-voltage drop below the
UVP threshold on any VDD or GVDD_X pin results in all half-bridge outputs immediately being set in the high-
impedance (Hi-Z) state and SD being asserted low. The device automatically resumes operation when all supply
voltages have increased above the UVP threshold.
DEVICE RESET
When RESET is asserted low, all power-stage FETs in the four half-bridges are forced into a high-impedance
(Hi-Z) state.
In BTL modes, to accommodate bootstrap charging prior to switching start, asserting the reset input low enables
weak pulldown of the half-bridge outputs. In the SE mode, the output is forced into a high-impedance state when
asserting the reset input low. Asserting the reset input low removes any fault information to be signaled on the
SD output, i.e., SD is forced high. A rising-edge transition on the reset input allows the device to resume
operation after an overload fault. To ensure thermal reliability, the rising edge of reset must occur no sooner than
4 ms after the falling edge of SD.
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