AD7175-8 : settling time of single conversion mode

Hi,

In continuous conversion mode, the timing for the very first conversion will be 28us and 24us for succeeding channels. Since in single conversion mode, the part is placed in standby mode after the conversion is complete. So it needs to come out of standby to power up and settle. Thus, the timing for the very first conversion will take longer than that in continuous conversion mode, approximately 128 modulator clocks or about 16us extra. This is the reason why you are seeing around 46us. However, I am not sure yet why you are seeing 13us instead of 24us. Do you have a scope shot of your digital interface? If you could also send to us your register map settings, it would be great.

Thanks,

Jellenie

Hi,

In continuous conversion mode, the timing for the very first conversion will be 28us and 24us for succeeding channels. Since in single conversion mode, the part is placed in standby mode after the conversion is complete. So it needs to come out of standby to power up and settle. Thus, the timing for the very first conversion will take longer than that in continuous conversion mode, approximately 128 modulator clocks or about 16us extra. This is the reason why you are seeing around 46us. However, I am not sure yet why you are seeing 13us instead of 24us. Do you have a scope shot of your digital interface? If you could also send to us your register map settings, it would be great.

Thanks,

Jellenie

Hello Jellenie,

Thank you for your prompt reply.

> If you could also send to us your register map settings, it would be great.

Yes, I'd like to confirm the register data.

ODR and filter type may defferent from customer's information.

Best regards,

y-suzuki

Hello Jellenie,

I got the register data.

That are followings.

0x01 (ADCMODE)     0x4010
0x02 (IFMODE)          0x0000
0x06 (GPIOCON)      0x0000
0x10 (CH0)                0x8010
0x11 (CH1)                0x8030
0x12 (CH2)                0x8050
0x13 (CH3)                0x8070
0x14 (CH4)                0x8090
0x15 (CH5)                0x80B0
0x16 (CH6)                0x80D0
0x17 (CH7)                0x80F0
0x20 (SETUPCON0)   0x0C00
0x28 (FILTCON0)        0x050

Coulf you please check these data ?

Best regards,

y-suzuki

Hi,

Can you confirm the FILTCON0 settings? Looks like it is not a valid value as you need to select a specific filter type. If you want ODR=125ksps with Sinc5+Sinc1 filter this should be 0x1. I would also suggest to enable the Data_Stat bit in the status register when multiple channels are enabled. I'm confused also about writing a command of 0x8010. What is this for? The customer should always need to start writing to communication register. So to initiate the single conversion mode, you have to write 0x01 then followed by the data to write to the ADCMODE register which is 0x4010 in this case. If the customer wants to monitor the start of conversion they can use the SYNC pin to inititate conversion.

Thanks,

Jellenie

ello Jellenie,

> If you want ODR=125ksps with Sinc5+Sinc1 filter this should be 0x1.

I understood the setting of  FILT0 as followings.
  desired condition: ODR=125ksps , select Sinc5+Sinc1 filter, disable enhansed filter
  ENHFILTEN0 : "0"
  ENHFILT0 : "101" (default)  <- not valid by "ENHFILTEN0"
  ORDER0 : "00"
  ODR0 : "00001"
then the FILTCON0 register value is 0x0501
Does it wrong value ?

Best regards,

y-suzuki

Hi,

Yes, that's correct it should be 0x0501.

Thanks,

Jellenie