SLOA250C July 2017 – June 2022 TAS2505 , TAS2505-Q1
Information regarding short and open load fault conditions for the speakers of the TAS2505-Q1 amplifier can be accessed through two integrated registers using I2C. External host can poll the two registers (registers 62 and 46) to see if an error occurred. See Table 4-1 to interpret the error. There is no requirement on how often to poll these registers as the device self protects on the event of an error.
To determine whether or not a short has occurred, the host reads register 45 of page 1. If bit D1 of this register is low, then a short condition exists in the amplifier and has caused it to shut down. The fault condition needs to be fixed before it can operate again. If this bit is high, then no short circuit condition has been detected.
The other primary type of output fault condition, open load, can also be read through I2C. To do this, the first output of the LM2903 dual comparator is routed back to the GPIO/DOUT pin. Additionally, you should first mute the amplifier to stop switching at the outputs. To do this, set bit D1 of register 45 from page 1 to 0. Then write "00001000" or "0x08" to register 52 of page 0. This sets the GPIO/DOUT control register to its general input setting. The first output of the comparator is then automatically written to this register and stored in bit D1 as a high or low bit. It is then possible to read back register 52 of page 0 at any time and determine if an open load fault has occurred, by comparing its D1 bit with the D1 bit of register 46 on page 1. Once diagnostic reading is complete, ensure that D1 of register 45 from page 1 is reset back to 1 to re-enable the amplifier. If a fault was detected, it needs to be corrected before sound can be played again. Table 4-1 demonstrates the register information that corresponds to each primary state of amplifier operation.
Amplifier State | Page 0, Register 52, Bit D1 | Page 1, Register 46, Bit D1 |
---|---|---|
No Fault | 1 | 1 |
Short Circuit | X | 0 |
Open Load | 0 | 1 |
Amplifier State | Comparator Out 1 | Comparator Out 2 | Page 1, Reg 46, Bit 1 |
---|---|---|---|
No Fault | 1 | 1 | 1 |
Short to GND | 1 | 0 | 0 |
Short to Power | 0 | 1 | 0 |
Shorted Load | 1 | 1 | 0 |
Open Load | 0 | 0 | 1 |