ZHCSFV8C May 2016 – January 2018 TPA3128D2 , TPA3129D2
PRODUCTION DATA.
The TPA31xxD2 has a built-in voltage limiter that can be used to limit the output voltage level below the supply rail, the amplifier operates as if it was powered by a lower supply voltage, and thereby limits the output power. Add a resistor divider from GVDD to ground to set the voltage at the PLIMIT pin. An external reference may also be used if tighter tolerance is required. Add a 1-µF capacitor from pin PLIMIT to ground to ensure stability.
The PLIMIT circuit sets a limit on the output peak-to-peak voltage. The limiting is done by limiting the duty cycle to a fixed maximum value. The limit can be thought of as a "virtual" voltage rail which is lower than the supply connected to PVCC. The "virtual" rail is approximately four times the voltage at the PLIMIT pin. The output voltage can be used to calculate the maximum output power for a given maximum input voltage and speaker impedance.
where
PVCC (V) | PLIMIT VOLTAGE (V)(1) | R to GND | R to GVDD | OUTPUT VOLTAGE (Vrms) |
---|---|---|---|---|
24 V | GVDD | Open | Short | 17.9 |
24 V | 3.3 | 45 kΩ | 51 kΩ | 12.67 |
24 V | 2.25 | 24 kΩ | 51 kΩ | 9 |
12 V | GVDD | Open | Short | 10.33 |
12 V | 2.25 | 24 kΩ | 51 kΩ | 9 |
12 V | 1.5 | 18 kΩ | 68 kΩ | 6.3 |