TAS5352A datasheet(22/27 Pages) TI

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Overtemperature Protection

DEVICE RESET

Undervoltage Protection (UVP) and Power-On

TAS5352A

SLES239 – NOVEMBER 2008 ........................................................................................................................................................................................... www.ti.com

The

TAS5352A

has

two-level

Two reset pins are provided for independent control

temperature-protection

system

that

asserts

of half-bridges A/B and C/D. When RESET_AB is

active-low warning signal (OTW) when the device

asserted low, all four power-stage FETs in half--

junction temperature exceeds 125°C (typical) and, if

bridges A and B are forced into a high-impedance

the device junction temperature exceeds 155°C

(Hi-Z) state. Likewise, asserting RESET_CD low

(typical), the device is put into thermal shutdown,

forces all four power-stage FETs in half-bridges C

resulting in all half-bridge outputs being set in the

and D into a high-impedance state. Thus, both reset

high-impedance (Hi-Z) state and SD being asserted

pins are well suited for hard-muting the power stage if

low. OTE is latched in this case. To clear the OTE

needed.

latch, either RESET_AB or RESET_CD must be

In BTL modes, to accommodate bootstrap charging

asserted. Thereafter, the device resumes normal

prior to switching start, asserting the reset inputs low

operation.

enables weak pulldown of the half-bridge outputs. In

the SE mode, the weak pulldowns are not enabled,

and it is therefore recommended to ensure bootstrap

Reset (POR)

capacitor charging by providing a low pulse on the

The UVP and POR circuits of the TAS5352A fully

PWM inputs when reset is asserted high.

protect

the

device

any

power-up/down

and

Asserting either reset input low removes any fault

brownout situation. While powering up, the POR

information to be signaled on the SD output, i.e., SD

circuit resets the overload circuit (OLP) and ensures

is forced high.

that all circuits are fully operational when the

GVDD_X and VDD supply voltages reach stated in

A rising-edge transition on either reset input allows

the

Electrical

Characteristics

Table.

Although

the device to resume operation after an overload

GVDD_X and VDD are independently monitored, a

fault. To ensure thermal reliability, the rising edge of

supply voltage drop below the UVP threshold on any

reset must occur no sooner than 4 ms after the falling

VDD or GVDD_X pin results in all half-bridge outputs

edge of SD.

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.

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