Technical information

STA510A

12/21

DocID11077 Rev 4

4.2

Protection circuitry

The STA510A 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.

•

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 thesholds

under normal operation.

4.3

Power outputs

The STA510A 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 high-

impedance state during power-up until the logic power supply, VL, has settled.

4.4

Parallel output / high current operation

When using the DDX mode output, the STA510A outputs can be connected in parallel in

order to increase the output current capability to a load. In this configuration the STA510A

can provide up to 200 W into a 3-

Ω load.

This mode of operation is enabled with the 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 9.

4.5

Output filtering

A passive 2nd-order filter is used on the STA510A power outputs to reconstruct the analog

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

and choice of passive components. A filter design for 6- or 8-

Ω loads is shown in the

application circuit of Figure 8, and for 4-

Ω loads in Figure 9 and Figure 10.