STA506

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There are two possible modes subsequent to activating a fault:

– 1) SHUTDOWN mode: with FAULT (pull-up resistor) and TRI-STATE pins independent, an activated

fault will disable the device, signaling low at the FAULT output.

The device may subsequently be reset to normal operation by toggling the TRI-STATE

pin from

High to Low to High using an external logic signal.

– 2) AUTOMATIC recovery mode: This is shown in the Application Circuit of fig.1.

The FAULT and TRI-STATE pins are shorted together and connected to a time constant circuit com-

prising R59 and C58.

An activated FAULT will force a reset on the TRI-STATE pin causing normal operation to resume fol-

lowing a delay determined by the time constant of the circuit.

If the fault condition is still present , the circuit operation will continue repeating until the fault condition

is removed .

An increase in the time constant of the circuit will produce a longer recovery interval. Care must be

taken in the overall system design as not to exceed the protection thesholds under normal operation.

3.3 Power Outputs:

The STA506 power and output pins are duplicated to provide a low impedance path for the device's bridged

outputs .

All duplicate power, ground and output pins must be connected for proper operation.

The PWRDN or TRI-STATE pins should be used to set all MOSFETS to the Hi-Z state during power-up until the

3.4 Parallel Output / High Current Operation:

When using DDX Mode output , the STA506 outputs can be connected in parallel in order to increase the output

current capability to a load.

In this configuration the STA506 can provide 80W into 8 ohm or up to 120W into 4ohm.

This mode of operation is enabled with the CONFIG pin (pin.24) connected to VREG1 and the inputs combined

INLA=INLB, INRA=INRB and the outputs combined OUTLA=OTLB, OUTRA=OUTRB.

3.5 Additional Informations:

Output Filter: A passive 2nd-order passive filter is used on the STA506 power outputs to reconstruct an analog

Audio Signal .

System performance can be significantly affected by the output filter design and choice of passive components.

A filter design for 6ohm/8ohm loads is shown in the Typical Application circuit of fig.1. Figure 9 shows a filter

design suitable for 4ohm loads.

Figure 10 shows a filter for ½ bridge mode , 4 ohm loads.

Power Dissipation & Heat Sink requirements: The power dissipated within the device will depend primarily

on the supply voltage, load impedance and output modulation level.

The PowerSO36 package of the STA506 includes an exposed thermal slug on the top of the device to provide

a direct thermal path from the IC to the heatsink.

Careful consideration must be given to the overall thermal design . See figure 8 for power derating

versus Slug temperature using different heatsinks and considering the Rth-jc =1.5°C/W.