ADS8341: Malfunctioning issue after power-on

Sadanori Kato

Part Number: ADS8341

Tool/software:

Hi,

ADS8341EB may not work normally after power-on. The symptom is that BUSY keeps low and AD conversion cannot be performed. This is a malfunction in a product that is actually being used on the market. Especially, even when using the same board and the same component, the incidence of this symptom increases when Ta is 50°C or higher.
Have you had any experience with this in the past? Could the power supply ramp-up speed or input terminal handling cause a malfunction?
The schematic and the screenshots at power up are as follows.

Could you please give me any comments?

Best regards,
Kato

over 1 year ago

0 Tom Hendrick over 1 year ago

TI__Guru**** 181021 points

Hi Kato,

I've not seen this behavior with the ADS8341. Can you zoom in and capture the SDI, SCLK, /CS and BUSY lines?

0 Sadanori Kato over 1 year ago in reply to Tom Hendrick

Guru 36540 points

Hi Tom-san,

Thank you for your prompt reply.

This week is a holiday in Japan, so I will get back to you again next week.

Best regards,
Kato

0 Sadanori Kato over 1 year ago in reply to Sadanori Kato

Guru 36540 points

Hi Tom-san,

I would like to confirm how to set ADS8341EB up in internal clock mode after power-on.
According to page 13 of ADS8341EB data sheet, is my understanding correct that it should be performed the following steps (1) to (4)?

- Setup procedure for internal clock mode -
(1) Applying the power supply voltage
(2) Writing PD1 = 1 and PD0 = 0 to set for internal clock mode
(3) Writing PD1 = 0 and PD0 = 0 to set for power-down mode
(4) Writing PD1 = 1 and PD0 = 0 to resume to internal clock mode

Currently, the procedure above (2) was not applied. Could this be the cause of the abnormal behavior?
If the setup procedure from (1) to (4) for internal clock mode is correct, how should the /CS and DCLK signals be handled?

- Questions -
(a) Is it necessary to set /CS to "high" once between step (2) and step (3)? Or is it necessary to input DCLK?
(b) Is it necessary to set /CS to "high" once between step (3) and step (4)? Or is it necessary to input DCLK?

Best regards,
Kato

+1 Tom Hendrick over 1 year ago in reply to Sadanori Kato

TI__Guru**** 181021 points

Hi Kato,

If you plan to use the internal clock you need to enable that with (2) above. The DCLK is always needed when writing to or reading from the ADS8341. You don't need to toggle /CS high between commands.

0 Sadanori Kato over 1 year ago in reply to Tom Hendrick

Guru 36540 points

Hi Tom-san,

Thank you for your information.

This malfunctioning issue after power-on has been resolved.
I appreciate your cooperation.

Best regards,
Kato

0 Tom Hendrick over 1 year ago in reply to Sadanori Kato

TI__Guru**** 181021 points

Hi Kato-san,

Can you tell me what the resolution was?

0 Sadanori Kato over 1 year ago in reply to Tom Hendrick

Guru 36540 points

Hi Tom-san,

Even though BUSY keeps low after power-on, AD conversion can be performed successfully by applying the above the setup procedure (1) to (4).

Best regards,
Kato

0 Sadanori Kato over 1 year ago in reply to Sadanori Kato

Guru 36540 points

Hi Tom-san,

After power-on, the ADS8341EB can work normally regardless of the BUSY status, by following the initial setup procedure below.

However, even though /CS is "High", why does BUSY keep "Low" after power-on? In other words, why isn't BUSY high impedance? It seems that ADS8341EB cannot be initialized properly.

Best regards,
Kato

+1 Tom Hendrick over 1 year ago in reply to Sadanori Kato

TI__Guru**** 181021 points

Hi Kato,

The ADS8341 does not have any specific power on reset state which is why BUSY is sometimes held low at power up. If it does not respond properly after you initialize the device with your desired commands, that would be cause for concern.

0 Sadanori Kato over 1 year ago in reply to Tom Hendrick

Guru 36540 points

Hi Tom-san,

Thank you for your quick response.

I understand and will contact you if I have any additional questions.

Best regards,
Kato

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ADS8341: Malfunctioning issue after power-on