PCM1860: Schematic review and I2S bus function check

R1 Solder 0R

Are you planning to use Vin1 p and Vin1m as differential input. 

I see Vin1m and Vin2 m connected together. Why is this done?

We need to give a differential input between Vin1p and Vin1m  and a second differential input connected between Vin2p and Vin2m. 

The BCLK and FSYNC seem to be appearing from the chip so the issue is perhaps the input signal connections i mention

Hi Sir,

PCM1860 Input mode setting to difference and input architecture use virtual difference input so Vin1m and Vin2 m connected together.

some questions as below,

1.When will I2S data be output? 

2. Is there no output for I2S data without an input signal?

Thanks,

Tom

Hi Sir,

Supplementary Instructions:

1.I2S Data pin: the current output state is like DC 0V

2.When input differential 1Khz/1V signal to VINL- and VINL+ but I2S data pin still no data output (~0V) (After removing the R1 condition)

B/R

Tom

Please connect the differential signal to the Input side of Capacitors C8 and C9. Please disconnect R1,C10 and C11 for this test.

Please also send Oscilloscope plots of Vin L+ and Vin L- with Scope set to DC coupling and an input signal of 1 Khz applied

Hi Sir,

The measurement data as below,

1. disconnect R1,C10 and C11

2. measurement waveform-1

3. measurement waveform-2 (oscilloscope probe contact still over 5sec. and the DC offset voltage will still drop)

PS: I2S No data output, about ~0V

B/R

Tom

Hi Sir,

Some experimental results are as follows:

1.Disconnect R18 and connect R19 to change MD6/MD5/MD2 settings from 110 to 000 (SE Ch 1 (VINL1 and VINR1)

2. Reconnect R1, C10 and C11

3. Input 1Khz 0.1Vrms to VINL1/VIN1P and VINR1/VIN2P

4. The test result is the same as before, I2S has no data output.

B/R

Tom

I would expect that both the input  pins voltage should be 1.65v without any signal. With signal the signal should ride over the pin voltage.

It looks that the pin voltage on your chip is 500mv only and there is no DC Bias. 

Please disconnect the signals and check pin voltages of all input pins. You should see 1.65v. Please see snapshot below

Hi Sir,

In MD6/MD5/MD2 (000) SE Ch 1 (VINL1 and VINR1) mode, the measurement data is as follows,

Pin1 (VINL2/VIN1M), Pin2 (VINR2/VIN2M) and Pin27~30 DC Bias are 1.65V, but Pin3 and Pin4 have no DC Bias, why are there such measurement results?

Please help to troubleshoot this problem,

Thanks,

Tom

Hi Tom,

Apologies for the delay, Sanjay-san will respond as soon as possible. *For record keeping purposed please wait to respond until Sanjay has continued the thread.

Kind regards,

Tom, if the DC Bias on the pin is 1.65v then the sine waves seen on the input pins should be varying about 1.65v. Your Plots do not show this. Can you please recheck the pin waveforms. 

For this to work the pin signals should be varying about 1.65v

Hi Sir,

Is there any solution to my problem?

B/R

Tom

It looks that 2 or the 4 pins have the correct DC Bias on them. Its possible that the MD6,MD5,MD2 pins are not properly connected to the pins of the

IC such that differential mode is not selected properly. Alternatively it is possible that you have pin damage. Have you tried changing the chip?

Please check Below:

MD6 MD5 MD2

1          1       0

Hi Sir,

The new sample measurement data is as follows, set to differential mode, MD6/MD5/MD2 =110: Diff Ch 1 (VIN1P and VIN1M, VIN2P and VIN2M).

1. Pin 6 (VREF)/C17=1.63V & Pin 11 (LDO)/C29:=1.93V

2. Pin16 (LRCLK)/R24=48Khz & Pin 17 (BCK)/R25= ~3.07Mhz

3. Pin 18 (SDOUT)/R26: No dataoutput ~ 0V?

4. Pin1 , Pin2 , Pin3 , Pin4  DC Bias are drifts unstable about 0.25V (Why not 1.65V?)

5. Pin27 , Pin28 , Pin29 , Pin30  DC Bias are 1.65V.

My question is why P1~P4 don't have a DC bias of 1.65V?

Thanks,

Tom

Would you mind trying MD6 MD5 MD2 as 111 ? Does DC of 1.65 appear at pin 1-4 ?

Hi Sir,

As you said, I changed the mode of MD6 MD5 MD2 from 110 to 111, the input DC bias voltage data is as follows, I tried to input 1Khz to pin 30 then I2S data pin still no data output.

1. Pin1, Pin2, Pin3, Pin4 the DC Bias are about 0.0V

2. Pin27, Pin28, Pin29, Pin30 the DC Bias are 1.65V

I also tried 1Khz input to pin 30 in MD6 MD5 MD2 =110 mode and still no data output from I2S data pin,

Please give me your suggestion to solve this problem,

Thanks,

Tom

We shall try on an evaluation module and get back to you. Please give us some time .

Hi Sir,

Is there any solution to my problem?

B/R

Tom

EVM has been ordered. It will take some time to get to me. I shall update you soon

I set up a PCM1860 EVM.

With original settings from your side, I saw a Data output on Oscilloscope(Yellow).

LRCLK was 48K 

BCLK was 3.072Mhz

DC Voltage on Input pin 1 is 1.6v (Red)

The Below is the Link to EVM user Guide.

https://www.ti.com/lit/ug/slau615/slau615.pdf?ts=1665417901262&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FPCM1864EVM

My suggestion would be to Replace IC and Check ia all connections on the Board are fine.,

Dear Sir,

Some questions are as follows,

1. Is it set to differential mode, MD6/MD5/MD2 (110) and then measure the data?
2. Whether analog signal input is required when I2S data is output?

Thanks,

Tom

MD6/MD5/MD2 (110)  was the setting

No signal was applied

The Bias was present on all Input pins.

Dear Sir,

I have replaced the PCM1860 2 pcs purchased from TI's official website. The measured data is the same as the data before replacement.

Mode setting: MD6/MD5/MD2 =110: Diff Ch 1 (VIN1P and VIN1M, VIN2P and VIN2M).

1. Pin 6 (VREF)/C17=1.63V & Pin 11 (LDO)/C29:=1.93V
2. Pin16 (LRCLK)/R24=48Khz & Pin 17 (BCK)/R25= ~3.07Mhz
3. Pin 18 (SDOUT)/R26: No data output ~ 0V?
4. Pin1 , Pin2 , Pin3 , Pin4  DC Bias are drifts unstable about 0.25V (Why not 1.65V?)
5. Pin27 , Pin28 , Pin29 , Pin30  DC Bias are 1.65V.

My question is why P1~P4 don't have 1.65V DC bias and I2S data pin have no data output?

Any suggestions to troubleshoot this issue please?

could you open pin 1,2 3 4 by lifting pins from the Board. Then Check pin Waveform through an Oscilloscope and let me know what you see. Do not rely on a Multimeter.

I would also open the INT pin and check if there are pulses on INT Pin.

Dear Sir,

The measurement waveform is as follows,

1. Remove R2, R3, R4, R5, D4, D5, D6, D7 leaving P1 to P4 with only pcb traces

2. Measured waveforms of Pin 16 (LRCLK) , Pin 17 (BCK) and Pin 18 (DOUT)

3. The measurement waveforms of Pin 1 to Pin 4 and the waveform of Pin 2~4 are similar to Pin 1

PS: There is only one surge measured at the moment the oscilloscope probe touches

Hope to have some information on the solution to this problem

Thanks,

Tom

Have you opened INT Pin and seen measurements on this pin?

Also my suggestion is to lift the Pins 1 to 4 off the board and see the waveform on the pin itself. Do you see some waveform on the INT pin?

Dear Sir,

I left pin 19 (INT) unconnected as you suggested and the function of ADC seem worked and INT pin measurement data is about 0 voltage

How to properly control this INT pin, the datasheet mentions is that " pulling high for active mode" ?

Your suggestion helped a lot to solve the problem.

Thanks a lot,

Tom