TLV320AIC3100: short circuit detection and released

Hi Ajita,

1) The short-circuit flag will get set on short circuit detection. Reading the flag once will clear this flag. Reading it back again will determine if the short has been removed or not.

2) I'm not sure what you mean by parallel short, but the short circuit is measured not by impedance directly. If the current draw is excessive then the short will be reported. Since only a small current is being drawn, the device won't detect a short yet.

Best regards,
Jeff McPherson

Hi Jeff,

I have set page 0 /Register 48(INT1 control Register) as 0xC8 i.e enabled headphone detection, button detection and short circuit detection on INT1.

When I insert shorted/faulty headphone into jack,

1. Page 1 /Register 31(Headphone driver) => Reflects Headphone Insertion, doesn't reflect short circuit. 
2. Page 0 /Register 46 (Interrupt Flags—DAC) => Reflects Headphone Insertion, doesn't reflect short circuit.
3. Page 0 /Register 46 (Sticky/latched Interrupt Flags—DAC) => Reflects Headphone Insertion, does reflect short circuit.

Can you tell me why sticky flag but not non-sticky flag shows short circuit detection? Also note that short circuit of headphone are only observed when Audio is playing.

Thanks,

Ajita

Hi Ajita,

How are the non-sticky flags being measured? Sometimes these non-sticky registers will not report the interrupt 100% of the time due to noise or debounce so you may accidentally measure a moment in time where the non-sticky flag is low, especially since it's more efficient to only readback from one place. Sticky registers are more reliable and I would read those back to determine if a short is present. The flag can be read back to clear.

Best regards,

Jeff McPherson

Hi Jeff,

Here is detail explanation about my approach.

I want to get interrupt on short circuit (both Headphone and Speaker). Note: I have configured PLL, MICBIAS, SPK, Headphone initially and successfully able to play and record audio at 44100Hz.

Now short circuit steps are as below:

Step 1. I have configured Page 1 / Register 31 as "1100 0110" ==> enabled short circuit on headphones

Step 2. I have configured Page 0 / Register 67 as "1001 0111" ==> Enabled Headphone detection

Step 3. I have configured Page 0 / Register 48 as "1100 1000" ==> Enabled Headphone detection, Button-press detect, Short Circuit detection on INT1.

Step 4. I have configured Page 0 / Register 51 as "0001 0110" ==> Enabled INT1 on GPIO1

After following above steps, I am able to get headphone, button detection interrupt but not short circuit one. 

How I am checking short circuit interrupt now??
==> I am getting interrupt on headphone detection, so I read below registers. I am using shorted headphones which should trigger short circuit flag.

1) I read page 1 / Register 31 ==> D0 bit remains 0, doesn't reflect short circuit. 

2) I read page 0 / Register 46 (non-sticky flags i.e it doesn't get clear after user read)

Scenario 1: When no audio is playing.
==> On insertion of headphones, reads  0x10, detects headphone insertion, doesn't reflect short circuit
==> On Removal of headphones,  reads 0x00, detects headphone removal, doesn't reflect short circuit

Scenario 2: When audio is playing.
==> On insertion of headphones, read 0x1c, detects headphone insertion,  doesn't reflect short circuit, but DAC signal power is above threshold of DRC
==> On Removal of headphones, read 0x0c, detects headphone removal,  doesn't reflect short circuit, but DAC signal power is above threshold of DRC

3) I read page 0 / Register 44 (sticky flags i.e it gets clear after user read)

Scenario 1: When no audio is playing.
==> On insertion of headphones, reads  0x10, detects headphone, doesn't reflect short circuit. 
==> On Removal of headphones, reads 0x80, does reflect short circuit.

Scenario 2: When audio is playing.
==> On insertion of headphones, reads  0x80, does reflect short circuit.
==> On Removal of headphones, reads 0x1C, doesn't reflect short circuit. 

Can you tell me why sticky flag but not non-sticky flag shows short circuit detection? Also how to enable short circuit detection on speaker as well?

Thanks for your patience,
Ajita

Hi Ajita,

As I mentioned, live (non-sticky) registers can deal with noise or debounce problems that may prevent them from reading back the correct value 100% of the time. Sticky registers capture the interrupt and hold it to read back regardless of what time.

I am not sure about shorted headphones. Can you give details about how the short is being created in the headphones? You might also try a hardwire short instead. Do you also notice the driver powering down according to Register 31?

Short circuit protection on the speaker cannot be turned off. It is on by default. 

Best regards,
Jeff McPherson

Hi Jeff,

I can work with sticky registers. I have shorted left audio with ground for left audio also right audio with ground for right audio. Which make it short circuit. I have configured headphone driver short circuit behavior as power down. It works accordingly. How to configure speaker short circuit behavior? Default its on current limiting, it doesn't shut down speaker.

Thanks,

Ajita

Hi Ajita,

There is no configuration available for the speaker short circuit behavior. It is hardwired to the device and will always be active.

Best regards,
Jeff McPherson