SLOS970B January 2018 – January 2025 TPA6404-Q1
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The gain of the TPA6404-Q1 is configurable in the gain control register through I2C. There are four gain settings of 10 dB, 16 dB, 22 dB, and 28 dB. 22 dB is the default setting. It is recommended to select the lowest possible gain for the expected PVDD operation and input voltage range to minimize output noise and optimize dynamic range performance.
The combination of input voltage range and supply voltage sets the requirement for the chosen gain setting. Table 7-1 below shows examples:
| INPUT VOLTAGE | SUPPLY VOLTAGE | GAIN |
|---|---|---|
| 0.5 Vrms Single ended | 14.4V | 28dB |
| 1 Vrms Single ended | 14.4V | 22dB |
| 1 Vrms Differential | 14.4V | 16dB |
| 2 Vrms Single ended | 14.4V | 16dB |
| 2 Vrms Differential | 14.4V | 10dB |
| 1 Vrms Single ended | 18V | 28dB |
| 1 Vrms Differential | 18V | 22dB |
| 2 Vrms Single ended | 18V | 22dB |
| 2 Vrms Differential | 18V | 16dB |
The input impedance is a function of the selected gain, see Table 7-2.
| GAIN | INPUT IMPEDANCE | INPUT CAPACITOR | HIGH-PASS FILTER |
|---|---|---|---|
| 10dB | 80kΩ | 1µF | 2Hz |
| 16dB | 40kΩ | 1µF | 4Hz |
| 22dB | 20kΩ | 1µF | 8Hz |
| 28dB | 10kΩ | 1µF | 16Hz |
The inputs need to be AC-coupled to minimize the output DC-offset and ensure correct ramping of the output voltages during power-ON and power-OFF. The input AC-coupling capacitor together with the input impedance forms a high-pass filter with the following cut-off frequency:
Figure 7-2 Input High Pass Filter CalculationIf a flat frequency response is required down to 20Hz the recommended cut-off frequency is a tenth of that, 2Hz. Table 7-2 lists the high-pass filter frequency when using a 1µF AC-coupling capacitor. If lower high-pass filter frequencies are needed then larger capacitor values should be used.
It is recommenced to use AC-coupling capacitors with low leakage current, like ceramic-, film- or quality electrolytic-capacitors.
The TPA6404-Q1 has an output DC detection built it to protect the attached speaker in case an input AC-coupling capacitor fails or has too high leakage current.