AFE4490: Questions about how to use AFE4490

Takashi Matsumura

Part Number: AFE4490

I have a question about the contents of pages 36-38 of the AFE4490 specification.
Since the clock is 4MHz and the total count of EXAMPLE in Table 2 is 8000,
1 / 4MHzX8000 = 2ms. I understand that the PRP in Fig64 of the timing chart is 2ms.
Is it possible to shorten this measurement cycle of 2ms to 1ms?

If the 8MHz clock is changed to the 16MHz clock in Fig59 on page 33, IC will become inoperable.
Is it possible to set the register to acquire only the data of either LED1 (IR) or LED2 (RED)?
I understand from the specifications that such a setting is not possible.
The purpose is to change the measurement cycle from 2ms to 1ms.

over 2 years ago

0 Nick Zahabizadeh over 2 years ago

TI__Expert 4134 points

Hello Matsumura-san,

Welcome to the E2E design forums. I've viewed your ticket, please allow me 24 hours for providing a response.

Kind regards,
Nick Zahabizadeh

0 Nick Zahabizadeh over 2 years ago in reply to Nick Zahabizadeh

TI__Expert 4134 points

Hello Matsumura-san,

The Pulse Repetition Period is a function of the Pulse Repetition Frequency. PRP = 1/PRF.
The PRF can be configured from 62.5 to 5000 samples per second. Therefore, with a PRF pf 1000 SPS, you'll achieve a PRP of 1ms.

You can choose to not take any measurement of the IR sensor by modifying when the rising and falling edges of the IR phase will be. By making the rising edge of the IR sensor after the falling, it'll never take an IR measurement.

Kind regards,
Nick

0 Takashi Matsumura over 2 years ago in reply to Nick Zahabizadeh

Prodigy 60 points

Dear Mr. Nick,
Thank you for your support.
Is "PRF = 62.5min.-5000max" the result of the text "PRPCOUNT values should be set in the range 800-64000" on page 72?
The value of EXAMPLE in Table 2 on page 36 is the value under the condition of PRF = 500.
If PRF = 1000, change all values to 1/2 and attach the settings for that.
Is this setting okay if I use both LED1 (IR) and LED2 (RED)?

AFE4490registersetting.pdf