I'm now pn the promotion to my customer, but there is some abnormal phenomenon. so I hope to get a help from AE team.
#1. actually, customer is now using 16channels(IN16 to IN31) as a input. But the last channel (IN31) data is something wrong. so when customer changes to the other Input (IN 32 to IN 47), only IN47 input channel makes adnormal data than normal channel (some data is high and some data is low than normal)
#2. about INPUT range (PGA0~2), when I change PGA2~0 to get the different output. that output is not linearlyty. Is this corrent output?
ex,, Range1=0 R2=1 R3=2 R4=3 R5=2.5 R6=1.5 R7=0.5
TEXAS INSTRUMENTS KOREA,
AIP, FIELD APPLICATION ENGINEER.
Max, Roh ( firstname.lastname@example.org ) +82-10-9184-7484
#1. The question is not very clear. If you could share some numbers (how much higher or lower) and schematic (what is the input connected to, what is the ADC and the corresponding timing), it would help understand this better.
#2. You mentioned Range1=0 R2=1 etc, can you tell me what are the units of measurement. Some data would help (what is the analog output on OUTP OUTM looking like for each of these ranges).
I would be glad to help. Please give me the data.
Dear Surendranath Nagesh
Out customer is using AFE0064.
For your request,
#1. Refer to below pictures and tes condition
1) Integration time = 66uS
With 2V, the input current will be (2V-EXT_C)/8.3Mohm = (2-1.6)/8.2M = 48.8nA
With integration time of 66us, the input charge is = 48.8nA*66us = 3.22pC
For this charge range, the customer has to use minimum of range 5, other wise the AFE outputs will be non-linear as they will saturate.
I am not able to zoom into the picture for #2 that you have attached. Or Can you please send me one where I can zoom and see. Is this measurement of OUTP-OUTM or only OUTP?
Also, can you please provide me the following additional information?
1) I wish to have the timing being used? I wish to see the complete timing diagram along with the various time duration.
2) Can you please verify customer is using integrate down mode?
3) What is the application? Have they considered using DDC264? It has integrated ADC and may be easier to use. If they cannot use DDC, can you please find the reason?
Thanks for your quick reply..
Our customer is on a vacation now. I'll inform you after return to work.
Dear Mr. Surendranath Nagesh.
Pls refer to the reply below.
1) Refer to attached file.5078.AFE_ADC_timing.zip
2) Yes, she used Integrate down mode.
3) Apllication : Infra Red Night Vision Camera for automotive.
I've already promoted DDC264, and she is interested in powerful performance of DDC264. But she want to know why AFE0064 did not work as expectation now.
1) Last channel data issue: As per the mail from Max Roh, when IN16 to IN31 is used, IN31 is abnormal and when IN32 to IN47 is used, IN47 is abnormal. So the issue is actually on the first channel that is being shifted out on OUTP/OUTM. The ADC inputs may not be settling. The customer could move the ADC convert start edge ADC_NCONVST closer to the next rise edge of AFE_CLK to give more time for the ADC inputs to settle.
2) The AFE0064 output is=integrator output at SHS fall-integrator output at SHR fall.
Since the input charge is large (3.22pC), the outputs of the AFE0064 will be correct only in range 5, 6 and 7. Below range 5, the SHS sample will have saturated and hence the SHS-SHR value will be smaller and the output will reduce. So this behavior is as expected.
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