STA516B

Applications information

Doc ID 13183 Rev 4

11/17

5.2

Protection circuitry

The STA516B includes protection circuitry for overcurrent and thermal overload conditions.

A thermal warning pin (THWARN, pin 28, open drain MOSFET) is activated low when the IC

temperature exceeds 130 °C, just in advance of thermal shutdown. When a fault condition is

detected an internal fault signal immediately disables the output power MOSFETs, placing

both H-bridges in a high-impedance state. At the same time the open-drain MOSFET of pin

FAULT (pin 27) is switched on.

There are two possible modes subsequent to activating a fault.

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Shutdown mode: with pins FAULT (with pull-up resistor) and TRISTATE separate, an

activated fault disables the device, signalling a low at pin FAULT output.

The device may subsequently be reset to normal operation by toggling pin TRISTATE

from high to low to high using an external logic signal.

"

Automatic recovery mode: This is shown in the applications circuits below where pins

FAULT and TRISTATE are connected together to a time-constant circuit (R59 and C58).

An activated fault forces a reset on pin TRISTATE causing normal operation to resume

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

If the fault condition persists, the circuit operation repeats until the fault condition is

cleared.

An increase in the time constant of the circuit produces a longer recovery interval. Care

must be taken in the overall system design not to exceed the protection thresholds

under normal operation.

5.3

Power outputs

The STA516B power and output pins are duplicated to provide a low-impedance path for the

device bridged outputs. All duplicate power, ground and output pins must be connected for

proper operation.

The PWRDN or TRISTATE pin should be used to set all power MOSFETs to the

5.4

Parallel output / high current operation

increase the output current capability to the load. In this configuration the STA516B can

provide up to 400 W into a 3-

Ω load.

This mode of operation is enabled with pin CONFIG (pin 24) connected to pin VDD. The

inputs are joined so that IN1A = IN1B, IN2A = IN2B and similarly the outputs

OUT1A = OUT1B, OUT2A = OUT2B as shown in Figure 8.

5.5

Output filtering

A passive 2nd-order filter is used on the STA516B power outputs to reconstruct the analog

audio signal. System performance can be significantly affected by the output filter design

and choice of passive components. Filter designs for 3- and 6-

Ω loads are shown in the

applications circuits of Figure 7, Figure 8 and Figure 9.