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TAS5352A

SLES239A – NOVEMBER 2008 – REVISED DECEMBER 2016

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Copyright © 2008–2016, Texas Instruments Incorporated

Setting the OC threshold too low might cause issues such as lack of enough output power or unexpected

shutdowns due to too-sensitive overload detection.

In general, TI recommends following the external component selection and PCB layout in the Detailed Design

Procedure closely.

For added flexibility, the OC threshold is programmable within a limited range using a single external resistor

connected between the OC_ADJ pin and AGND. See the Electrical Characteristics table for information on the

correlation between programming-resistor value and the OC threshold.

NOTE

A properly functioning overcurrent detector assumes the presence of a properly designed

demodulation filter at the power-stage output. It is required to follow the guidelines in

Table 3 when selecting the OC threshold and an appropriate demodulation inductor.

Table 3. Overcurrent Resistor Selection

OC-ADJUST RESISTOR VALUES (k

Ω)

MAX CURRENT BEFORE OC OCCURS (A), TC = 75°C

22

10.9

33

9.1

47

7.1

The reported maximum peak current in the table above is measured with continuous current in 1

Ω, one channel

active and the other one muted.

7.3.4.3 Pin-to-Pin Short-Circuit Protection (PPSC)

The PPSC detection system protects the device from permanent damage in the case that a power output pin

(OUT_X) is shorted to GND_X 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 start-up, that is, when VDD is supplied, consequently a short to either GND_X or PVDD_X after

system start-up 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 pins. If no shorts are present the PPSC detection passes, and

SD 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, TI recommends not to insert any resistive load to GND_X or PVDD_X.

7.3.4.4 Overtemperature Protection

The TAS5352A 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, either

RESET_AB or RESET_CD must be asserted. Thereafter, the device resumes normal operation.

7.3.4.5 Undervoltage Protection (UVP) and Power-On-Reset (POR)

The UVP and POR circuits of the TAS5352A fully protect the device in any power up, power down, or brownout

situations. 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 stated in the Electrical Characteristics.

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.