AMC1303E0510 Datasheet, PDF (27/40 Pages) Texas Instruments – Small, High-Precision, Reinforced Isolated Delta-Sigma Modulators with Internal Clock

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AMC1303E0510, AMC1303M0510, AMC1303E0520, AMC1303M0520
AMC1303E2510, AMC1303M2510, AMC1303E2520, AMC1303M2520
SBAS771 – JUNE 2017
9.2.2 Isolated Voltage Sensing
The AMC1303 is optimized for usage in current-sensing applications using low-resistance shunts. However, the
device can also be used in isolated voltage-sensing applications if the effect of the (usually higher) value of the
resistor used in this case is considered. For best performance, TI recommends using the ±250-mV versions of
the device (AMC1303x25xx) for this use case.
Figure 50 shows a simplified circuit typically used in high-voltage-sensing applications. The high value resistors
(R1 and R2) are used as voltage dividers and dominate the current value definition. The resistance of the
sensing resistor R3 is chosen to meet the input voltage range of the AMC1303. This resistor and the differential
input resistance of the AMC1303x25x is 22 kΩ also create a voltage divider that results in an additional gain
error. With the assumption of R1, R2, and R_IND having a considerably higher value than R3, the resulting total
gain error can be estimated using Equation 4, with E_G being the gain error of the AMC1303.
E_Gtot
= E_G
+ ^R3
R_IN
(4)
This gain error can be minimized during the initial system-level gain calibration procedure.
High Voltage
Potential
R1
3.3 V
or 5 V
AVDD
AMC1303x25x
R2
AINP
R4
R5
IIB
R3
RIND
AINN
û Modulator
R3'
R4'
R5'
AGND
AGND
VCM = 1.9 V
Figure 50. Using the AMC1303x25x for Isolated Voltage Sensing
9.2.2.1 Design Requirements
Table 2 lists the parameters for the typical application in the Isolated Voltage Sensing section.
Table 2. Design Requirements
PARAMETER
High-side supply voltage
Low-side supply voltage
Voltage drop across the resistor R3 for a linear response
VALUE
3.3 V or 5 V
3.3 V or 5 V
AMC1303x25x: ±250 mV (maximum)
Copyright © 2017, Texas Instruments Incorporated
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