STA518

Technical information

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The STA518 includes protection circuitry for over-current and thermal overload conditions. A

thermal warning pin (pin.28) is activated low (open drain MOSFET) when the IC

temperature exceeds 130°C, in advance of the thermal shutdown protection. When a fault

condition is detected , an internal fault signal acts to immediately disable the output power

MOSFETs, placing both H-Bridges in high impedance state. At the same time an open-drain

MOSFET connected to the fault pin (pin.27) is switched on.

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 Audio Application Circuit of Quad

single Ended). The FAULT and TRI-STATE pins are shorted together and connected to

a time constant circuit comprising R59 and C58.

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

resume following 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.

4.2

Power outputs:

The STA518 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

4.3

Parallel output / high current operation:

When using DDX Mode output , the STA518 outputs can be connected in parallel in order to

increase the output current capability to a load. In this configuration the STA518 can provide

70W into 8 ohm.

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.

4.4

Additional informations:

Output Filter: A passive 2nd-order passive filter is used on the STA518 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 Figure 9.

Quad Single ended circuit (Figure 1) shows a filter for ½ bridge mode, 4 ohm loads.