Part Number: ADC3660
Hi TI team,
I am currently using ADC3660 and encountered an issue where the digital output code does not match the expected value.
I am using an FPGA to capture the digital output from the ADC.
I have already verified the digital interface by enabling the ramp pattern mode, and the FPGA can correctly decode the incrementing digital pattern. Therefore, I believe the digital interface timing and FPGA decoding are working properly.
For the analog input test:
- AINP = 0.95V
- AINN = 0.95V
Based on my understanding, the ADC output should be close to mid-scale (around 32768 for 16-bit output). However, the actual captured value is only around 21636, which seems unreasonable.
I would like TI to help review whether there may be any issue in the schematic or analog front-end design.
However, due to confidentiality concerns, I cannot upload the schematic publicly on E2E.
Would it be possible to share the schematic through a private review method for checking?
The following are my software settings.
# System setting
# 16-bit 2-wire
# CLKP: 20MHz, DCLK: 80MHz
# use internal voltage reference
# single-ended clk input
# differential analog data input
# output format: offset binary
# CMD format:
# spi_write reg_addr reg_HEXvalue
#step0: reset
spi_write 00 01
sleep 0.001
#step1: select the output interface bit mapping
spi_write 07 4B
#step2: use E-fuse
spi_write 13 01
sleep 0.001
spi_write 13 00
#step3: set CMOS output buffer
spi_write 0A 7F
spi_write 0B EE
spi_write 0C FC
#step4: enable DCLK i/o buffer
spi_write 18 10
#step5: set FCLK
spi_write 19 12
#step6: set resolution to 16bit
spi_write 1B 88
#step7: set DCLK
spi_write 1F 50
#step8: set FCLK duty cycle(default setting)
spi_write 20 00
spi_write 21 FC
spi_write 22 0F
# set voltage ref and clk input type
spi_write 0E 09
# DLL PDN on
spi_write 11 04
# enable digital features block
spi_write 24 04
sleep 0.001
# change chnnel A/B data format to offset binary
spi_write 8F 02 # change A ch data format from signed to unsigned
spi_write 92 02 # change B ch data format from signed to unsigned
Thanks.