Hi ADI team,
Setup (simplified):
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AVDD = 3.3 V
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IOUT = 1 mA from AD7124 to a piezoresistive sensor
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Effective load ≈ 5 kΩ
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Measurement on a separate differential pair (AIN2/AIN3)
Observation:
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With the sensor connected, the current collapses to ~0.86 mA.
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The sensor’s IN+ node sits around ~2.8 V.
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Datasheet shows IOUT output compliance ≈ AVDD − 0.48 V, so at 3.3 V I only have ~2.82 V headroom, which explains the drop for a 5 kΩ load at 1 mA.
Question:
With AVDD fixed at 3.3 V, is there any recommended method using the AD7124 (or a simple adjunct circuit) to maintain a true 1 mA through a ~5 kΩ load without current drop (i.e., overcoming the compliance limit)? Or is the only practical approach to raise AVDD, reduce IOUT, or use an external precision current source?
Thanks,
Batu
