TDA7562 Просмотр технического описания (PDF) - STMicroelectronics

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TDA7562

MULTIFUNCTION QUAD POWER AMPLIFIER WITH BUILT-IN DIAGNOSTICS FEATURES

STMicroelectronics 

TDA7562

DIAGNOSTICS FUNCTIONAL DESCRIPTION

Detectable conventional faults are:

- SHORT TO GND

- SHORT TO Vs

- SHORT ACROSS THE SPEAKER

The following additional features are provided:

- OUTPUT OFFSET DETECTION

The TDA7562 has 2 operating statuses:

1) RESTART mode. The diagnostic is not en-

abled. Each audio channel operates inde-

pendently from each other. If any of the a.m.

faults occurs, only the channel(s) interested is

shut down. A check of the output status is made

every 1 ms (fig. 14). Restart takes place when the

overload is removed.

2) DIAGNOSTIC mode. It is enabled via I2C bus

and self activates if an output overload (such to

cause the intervention of the short-circuit protec-

tion) occurs to the speakers outputs . Once acti-

vated, the diagnostics procedure develops as fol-

lows (fig. 15):

- To avoid momentary re-circulation spikes from

giving erroneous diagnostics, a check of the out-

put status is made after 1ms: if normal situation

(no overloads) is detected, the diagnostic is not

performed and the channel returns back active.

-Instead, if an overload is detected during the

check after 1 ms, then a diagnostic cycle having a

duration of about 100 ms is started.

-After a diagnostic cycle, the audio channel inter-

ested by the fault is switched to RESTART mode.

The relevant data are stored inside the device

and can be read by the microprocessor. When

one cycle has terminated, the next one is acti-

vated by an I2C reading. This is to ensure con-

tinuous diagnostics throughout the car-radio oper-

ating time.

-To check the status of the device a sampling

system is needed. The timing is chosen at micro-

processor level (over half a second is recom-

mended).

Figure 14. Restart timing without Diagnostic Enable

Each 1mS time, a sampling of the fault is done

1-2mS

1mS

1mS

1mS

1mS

Out

Overcurrent and short

circuit protection intervention

(i.e. short circuit to GND)

Figure 15. Restart timing with Diagnostic Enable

1mS

100mS

t

Short circuit removed

1mS

1mS

Overcurrent and short

(i.e. short circuit to GND)

t

Short circuit removed

8/17

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