TAS5261 datasheet(17/21 Pages) TI

17 / 21 page

www.ti.com

Error Reporting

Over Current (OC) Protection With Current

Device Protection System

TAS5261

SLES188 – AUGUST 2006

Limiting and Overload Detection

The

and

OTW

pins

are

both

active-low,

open-drain

outputs.

Their

function

for

The device has independent, fast-reacting current

protection-mode signaling to a PWM controller or

detectors with programmable trip threshold (OC

other system-control device. Any fault resulting in

threshold) on all high-side and low-side power-stage

device shutdown is signaled by the SD pin going low.

FETs. See Table 3 for OC-adjust resistor values. The

Likewise, OTW goes low when the device junction

detector outputs are closely monitored by two

temperature exceeds 115

°C. (see Table 2).

protection systems. The first protection system

controls the power stage in order to prevent the

Table 2. Error Reporting

output current from further increasing. For instance, it

performs a current-limiting function

rather

than

OTW

DESCRIPTION

prematurely shutting down during combinations of

Over Temperature (OTE) or Over

high-level music transients and extreme speaker

Load (OLP) or Under Voltage (UVP)

load impedance drops. If the high-current situation

Over Load (OLP), PWM Activity

persists, i.e., the power stage is being overloaded, a

Dectector, or Under Voltage (UVP)

second

protection

system

triggers

latching

Over Temperature Warning. Junction

shutdown, resulting in the power stage being set in

temperature higher than 125

°C.

the high-impedance (Hi-Z) state.

Normal operation. Junction

temperature lower than 125

°C.

Table 3. OC-Adjust Resistor Values

It should be noted that asserting RESET low forces

CURRENT BEFORE OC OCCURS

OC-ADJUST

(A)

the SD and OTW signals high, independent of faults

RESISTOR VALUES

Ω) (1)

being present. It is recommended to monitor the

MIN

TYP

MAX

OTW signal using the system microcontroller and

respond to an overtemperature warning signal by, for

example, turning down the volume to prevent further

heating of the device resulting in device shutdown

(OTW). To reduce external component count, an

internal pullup resistor to 3.3 V is provided on both

100

the SD and OTW outputs. Level compliance for 5-V

(1)

Resistor tolerance is

±5%.

logic can be obtained by adding external pullup

resistors to 5 V (see the Electrical Characteristics

For

lowest-cost

bill

materials

terms

section of this data sheet for further specifications).

component selection, the OC threshold current

should be limited, considering the power output

requirement

and

minimum

load

impedance.

Higher-impedance

loads

require

lower

The TAS5261 contains advanced protection circuitry

threshold.

carefully designed to facilitate system integration and

ease of use, as well as safeguarding the device from

The demodulation filter inductor must retain a

permanent failure due to a wide range of fault

minimum of 5-H inductance at twice the selected OC

conditions, such as short circuit, overload, and

threshold current.

undervoltage. The TAS5261 responds to a fault by

Most inductors have decreasing inductance with

immediately

setting

the

power

stage

increasing

temperature

and

increasing

current

high-impedance state (Hi-Z) and asserting the SD

(saturation).

some

degree,

increase

pin low. In situations other than overload, the device

temperature naturally occurs when operating at high

automatically recovers when the fault condition has

output currents, due to inductor core losses and the

been

removed

(e.g.,

the

voltage

supply

has

dc resistance of the inductor copper winding. A

increased). For highest possible reliability, recovering

thorough analysis of inductor saturation and thermal

from an overload fault requires external reset of the

properties is strongly recommended.

device no sooner than 1 s after the shutdown (see

the Device Reset section of this data sheet).

Setting the OC threshold too low might cause issues,

such as lack of enough output power and/or

unexpected shutdowns due to sensitive overload

detection.

In general, it is recommended to follow closely the

external component selection and PCB layout as

given in the Application Information section of this

data sheet.

Submit Documentation Feedback

TAS5261 Datasheet(PDF) 17 Page - Texas Instruments

TAS5261 Datasheet(HTML) 17 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Datasheet Download

Link URL