SLOS970B January 2018 – January 2025 TPA6404-Q1
PRODUCTION DATA
The impedance magnitude value was measured during the second stage or phase measurement stage. These values are stored in register 0x17 through 0x1A, one register per channel. The hexadecimal value must be converted to decimal and used to calculate the impedance magnitude using the following equation:
Figure 7-5 AC Magnitude CalculationWhere:
Gain is the value chosen in register 0x15
I is the current chosen in register 0x16
An alternative is to use the values in Table 7-3 to determine the magnitude of the impedance using the ohms / code value. Change the code to decimal for this calculation.
| Setting | Gain at 18.75kHz Ohm / Code (decimal) | I (mA) | Impedance Range | Ohm / Code (decimal) |
|---|---|---|---|---|
| Reg 0x15 bit 7, 5 = 1 Reg 0x16 bit 2 = 1 | 4 | 20 | 0 to 6Ohms | 0.029643 |
| Reg 0x15 bit 7, 5 = 1 Reg 0x16 bit 2 = 0 | 4 | 10 | 0 to 12Ohms | 0.059287 |
| Reg 0x15 bit 7, 5 = 0 Reg 0x16 bit 2 = 1 | 1 | 20 | 0 to 24Ohms | 0.11857 |
| Reg 0x15 bit 7, 5 = 0 Reg 0x16 bit 2 = 0 | 1 | 10 | 0 to 48Ohms | 0.23714 |