Running AFE4400 at lower frequency

Santhana Kumar

Prodigy 150 points

Other Parts Discussed in Thread: AFE4400, AFE4404

I need few clarification regarding AFE4400 as listed below:

As per the datasheet, the typical value for crystal is 8 MHz with no upper and lower limits mentioned. With 8 MHz crystal, the lowest possible pulse repetition period is 61 Hz(4000000/65535). But I want to run the led at 12 Hz. Is it possible to do so with the standard 8 MHz crystal by changing any register settings? If not, can we reduce the crystal frequency to achieve the required pulse repetition period and what are its upper and lower limits?
Also, I want to run the ADC at 1.8 KHz while the LED is switching at 12 Hz. Is it possible to run ADC and LED at different frequencies.

Please let me know whether the above scheme can be implemented using AFE4400.

Thanks,

Santhana Kumar

over 9 years ago

Praveen Aroul over 9 years ago

TI__Mastermind 49756 points

Hello Santhana Kumar,

Regarding your questions about AFE4400, the crystal frequency cannot be changed and hence the lowest PRF supported is 62.5 Hz.

For your application, you may want to check out the new part in the AFE44xx family: AFE4404.
AFE4404 supports flexible clocking options and Pulse repetition frequency in the range of 10 to 1K Hz.

Santhana Kumar over 9 years ago in reply to Praveen Aroul

Prodigy 150 points

Hi Praveen,

Thanks for the information. Regarding AFE4404, i could only find the pining description in the datasheet. I downloaded the datasheet from this link www.ti.com/.../afe4404.pdf. No register description or functional working of the AFE is detailed in this datasheet. Could you please share a more detailed document for AFE4404.

Thanks,

Santhana Kumar

Amy Schnoor over 9 years ago in reply to Santhana Kumar

TI__Mastermind 18285 points

Santhana,

The AFE4404 is currently a preview. When the part RTMs, it will be listed as active. We plan to release the device soon.

Santhana Kumar over 9 years ago in reply to Amy Schnoor

Prodigy 150 points

Hi Amy Schnoor,

Can you please forecast when this AFE4404 will reach market. As we have a development based on this AFE, we need to check and verify its working for our requirement. If it is expected to be released in near future, we can at least wait for this product.

Thanks,

Santhana Kumar

Santhana Kumar over 9 years ago in reply to Santhana Kumar

Prodigy 150 points

Hi Amy Schnoor,

I could see the user guide for AFE4404 EVM from TI website but could not find any link to buy the evaluation module. Can you please share me the link to buy the evaluation module.

Thanks,

Santhana Kumar

Amy Schnoor over 9 years ago in reply to Santhana Kumar

TI__Mastermind 18285 points

Santhana,

The EVM will also become available when the device releases to the market.

Amy Schnoor over 9 years ago in reply to Amy Schnoor

TI__Mastermind 18285 points

The AFE4404 is now released.

Santhana Kumar over 9 years ago in reply to Amy Schnoor

Prodigy 150 points

Hi Amy Schnoor,

Thanks for your information. As i mentioned earlier, i want to run the LED and ADC at different frequency. The LED will be pulsed at 12Hz and ADC will be sampling at 1800Hz. But, as per AFE4404 datasheet, the LED driving, ADC sampling and conversion states forms one PRP(pulse repetition period), implies LED and ADC cannot run independently or at different frequency. Please see the below timing diagram for my actual requirement. Please clarify whether this requirement can be achieved with AFE4404.

Thanks,

Santhana Kumar

Amy Schnoor over 9 years ago in reply to Santhana Kumar

TI__Mastermind 18285 points

Santhana,

The ADC sampling rate is fixed. You do have the option of changing the LED timing if you wish.

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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Running AFE4400 at lower frequency