AMC1304L05_15 Datasheet, PDF (27/39 Pages) Texas Instruments – AMC1304x High-Precision,Reinforced Isolated Delta-Sigma Modulators with LDO

www.ti.com
AMC1304L05, AMC1304L25, AMC1304M05, AMC1304M25
SBAS655C – SEPTEMBER 2014 – REVISED SEPTEMBER 2015
Typical Applications (continued)
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 AMC1304x05) or 12.5 kΩ (for the
AMC1304x25).
E_G (%)
¨§ 1
©
R4 _{¸· *100%}
R4' R3' _¹
(5)
9.2.2.3 Application Curve
Figure 54 shows the dependency of the input bias current on the common-mode voltage at the input of the
AMC1304.
20
0
-20
-40
-60
-80
AMC1304x05
AMC1304x25
-100
-0.2
0
0.2 0.4 0.6 0.8
1
1.2
V_CM (V)
D001
Figure 54. Input Current vs Input Common-Mode Voltage
9.2.3 Do's and Don'ts
Do not leave the inputs of the AMC1304 unconnected (floating) when the device is powered up. If both modulator
inputs are left floating, the input bias current drives them to the output common-mode of the analog front end of
approximately 2 V that is above the specified input common-mode range. As a result, the front gain diminishes
and the modulator outputs a bitstream resembling a zero input differential voltage.
Copyright © 2014–2015, Texas Instruments Incorporated
Submit Documentation Feedback
27
Product Folder Links: AMC1304L05 AMC1304L25 AMC1304M05 AMC1304M25