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AMC1306E05 Datasheet, PDF (28/40 Pages) Texas Instruments – Small, High-Precision, Reinforced Isolated Delta-Sigma Modulators with High CMTI
AMC1306E05, AMC1306E25, AMC1306M05, AMC1306M25
SBAS734 – MARCH 2017
www.ti.com
This additional series resistor (R3') influences the gain error of the circuit. The effect can be calculated using
Equation 5 with R5 = R5' = 50 kΩ and R4 = R4' = 2.5 kΩ (for the AMC1306x05) or 12.5 kΩ (for the
AMC1306x25).
E G(%)
§
¨©1
R4
R4' R3
'
·
¸¹
u
100%
(5)
9.2.2.3 Application Curve
Figure 55 shows the dependency of the input bias current on the common-mode voltage at the input of the
AMC1306.
60
40
20
0
-20
-40
-60
-80
-0.5 0 0.5 1 1.5 2 2.5 3 3.5
VCM (V)
D005
Figure 55. Input Bias Current vs Common-Mode Input Voltage
9.2.3 Do's and Don'ts
Do not leave the inputs of the AMC1306 unconnected (floating) when the device is powered up. If both modulator
inputs are left floating, the input bias current drives these inputs to the output common-mode of the analog front-
end of approximately 2 V. If that voltage is above the specified input common-mode range, the front gain
diminishes and the modulator outputs a bitstream resembling a zero input differential voltage.
28
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