We are testing the AFE 4490 overhere have have some questions regarding regarding the start up behaviour.
When starting up the AFE, we notice a relative long time before the data is accurate and stabilized. The datasheet mentions the time is > 1 s when data becomes accurate, in our tests we see that the signal of both LEDS are stabilized after about 400-600 samples (@ 200 Hz ~ 2-3 seconds). Is this a normal situation? Can this time somehow be decreased?
We also measured the voltage of TX reference volatage (TX_REF pin) during power up AFE4490 (AFE_PDN-pin going high) and see it takes about 2 seconds before the voltage is settled. Is it possible to e.g. lower the capacitor value of the TX_REF-pin so we decrease the settling time of the AFE LED driver?
The settings we use:
- LED/sensor combination Osram SFH7050
- Power supply voltage = 3.0 V
- Tx reference voltage = 0.5 V
- LED_RANGE = 50 mA
- TX_REF pin is coupled with capacitor of 2.2uF
Can someone give more information? Thanks!
