DAC81416EVM: TEMP ALM bit

Hi,

Are you able to read and write to the device?

if not, there is some issue with the board or device soldering.

Did you enable the internal reference by any chance? Whats the value you are writing into GENCONFIG register?

Did you configure SPICONFIG register to enable the outputs?

Let me the answers for above questions. your jumper settings are correct.

Also can you let me know the power up procedure and register writes you did after power up?

Regards,

AK

Hello AK.

Yes I am able to read and write into the device, I am attaching a screenshot of the register values. I am writing and reading values using the dac-evm software and the changes in values are reflected when I read back the registers.

Did you enable the internal reference by any chance? Whats the value you are writing into GENCONFIG register:

By selecting 1-2 I am using the on-board reference. If you are referring to the REF-PWDWN bit in GENCONFIG, I have set it to 1. GENCONFIG value that I am writing is 4000h.

Did you configure SPICONFIG register to enable the outputs?

DEV-PWDWN bit is set to 0. SPICONFIG=0A84h

Also can you let me know the power up procedure and register writes you did after power up?

My power up procedure is as follow:

1. connect usb2any jumper cable with dac-evm

2. turn on power supply inputs to dac

3. set registers one by one. read all registers->write into spiconfig, genconfig etc -> write dac values

Hi,

Are you using differential mode?  Also DAC output is connected to any load?

Did you write DACPWDN TO 0x0000 in address 0x09,  if not do the same and check.

Please do the following procedure as a debug.

1. Power up the device

2. Write SPICONFIG 0x0A84

3. Write GENCONFIG 0x7F00

4. Read the above two registers ( should be able to read the contents correctly)

5. Write BROADCONFIG 0x0000 ( default value is 0xFFFF)

6. Write DACPWDN 0x0000

7. Send DAC_DATA to any of the channels and observe the output.

Regards,

AK

Are you using differential mode?  Also DAC output is connected to any load?

No, I have set the DIFF-EN bits 0 in GENCONFIG register. No load is connected.

Did you write DACPWDN TO 0x0000 in address 0x09,  if not do the same and check.

I have tried the same but, even if I write 0000h in the DACPWDN register, when I read it back, it returns with FFFFh value.

Please do the following procedure as a debug.

I have followed these steps, except instead of 7F00h, I have written 4000h in the GENCONFIG register. Till this point, I have checked, I am able to read the contents correctly.

Only in step 6, the DAC-PWDN register returns FFFFh.

I also tried to set the ALM_RESET bit in TRIGGER register(Offset= 0Eh). But status register still returns 0009h.

Thanks,

Sufyan Khan

Hi,

Can you let me know the supply currents on VCC, VDD?

Regards,

AK

Hello AK,

I dont think the current drawn is in the measurement range of my Power supply. It is definitely less than 1mA. I have attached an image of the front panel for your reference.

Hi,

Seems like device is still in power down mode. 

Can you let me know the TEMPOUT pin reading? Also can you please check with another device?

Also make sure reference should come last.

Regards,

AK

Hi,

Tempout reading is 5V. Another device as in another Power supply? or DAC-EVM?

Hi,

This seems interesting. TEMP_OUT should not read 5V in any case.

Can you make sure that reference comes last in sequencing?

Can you check with another device, not another EVM, solder another device.

Meanwhile I will check this with my design team as well.

Regards,

AK

Upon close monitoring, I have noted that TEMP_OUT value is changing depending on DEV_PWDWN bit in SPICONFIG register. When DEV_PWDWN = 0, TEMPOUT shows 1.27V, whereas when DEV_PWDWN bit is  1, TEMP_OUT shows ~5V. However in both cases DAC_PWDWN register is stuck at FFFFh, hence no voltage is comes at output pins.

I checked with reference as last in sequence, i.e writing GENCONFIG last. It didn't make any difference. DAC_PWDWN register is fixed at FFFFh.

I don't have a spare IC at the moment. Can you send me a sample IC?

Sure, please check with your team. 

Thanks an regards,

Sufyan Khan 

Hi,

The temp_out temp sensor's output is pulled high during power down. So the Temp_out pin being high points to the device being in PDN state.

This is the reason its at 5V, expected behavior. Enable the DAC by DEV_PWDN = 0.

Did you check the reference voltage at DAC input? is it reading 2.5V? Can you please enable internal reference ( make sure appropriate jumpers are installed)

write GENCONFIG as 0x3F00 to enable internal reference and test the same.

Regards,

AK

Ref voltage on TP12 is 2.48V when I selected on board reference.

Leaving J11 open, I turned on internal reference and read 2.48V.

In both cases, I could not obtain any output.

What is the solution to not being able to write into the DAC_PWDN register. Everything else seems to work fine.

Hi,

I assume the device is still in power dwon state and ALM-RESET bit is set. To resume normal operation, the thermal alarm must be cleared through the ALM-RESET bit while the DAC channels are in power-down mode.

After that enable the DAC outputs and check.

Regards,

AK