21

AMC1035

www.ti.com

SBAS837B – AUGUST 2018 – REVISED APRIL 2020

Product Folder Links: AMC1035

Submit Documentation Feedback

Copyright © 2018–2020, Texas Instruments Incorporated

Typical Applications (continued)

8.2.1.1 Design Requirements

Table 2 lists the parameters for this typical application.

Table 2. Design Requirements

PARAMETER

VALUE

Supply voltage

3.3 V

Voltage drop across the sensing resistor RDC1 for a linear response

1 V (maximum)

Voltage drop across the sensing resistors RACx for a linear response

±1 V (maximum)

Current through the sensing resistors RACx

±100 µV (maximum)

8.2.1.2 Detailed Design Procedure

Use Ohm's Law to calculate the minimum total resistance of the resistive dividers to limit the cross current to the

desired values:

•

For the voltage sensing on the DC bus: RDC1 + RDC2 + RDC3 = VBUS / IDC

•

For the voltage sensing on the output phases U, V, and W: RAC1 + RAC2 + RAC3 = VPHASE (max) / IAC

Consider the following two restrictions to choose the proper value of the resistors RDC3 and RAC3:

•

The voltage drop caused by the nominal voltage range of the system must not exceed the recommended

input voltage range of the AMC1035: VxC3 ≤ VFSR

•

The voltage drop caused by the maximum allowed system overvoltage must not exceed the input voltage that

causes a clipping output: VxC3 ≤ VClipping

Use similar approach for calculation of the shunt resistor values RSHUNT and see the AMC1306M25 data sheet

for further details.

Table 3 lists examples of nominal E96-series (1% accuracy) resistor values for systems using 600 V and 800 V

on the DC bus.

Table 3. Resistor Value Examples for DC Bus Sensing

PARAMETER

600-V DC BUS

800-V DC Bus

Resistive divider resistor RDC1

3.01 MΩ

4.22 MΩ

Resistive divider resistor RDC2

3.01 MΩ

4.22 MΩ

Sense resistor RDC3

10 kΩ

10.5 kΩ

Resulting current through resistive divider IDC

99.5 µA

94.7 µA

Resulting voltage drop on sense resistor VRDC3

0.995 V

0.994 V

Table 4 lists examples of nominal E96-series (1% accuracy) resistor values for systems using 230 V and 690 V

on the output phases.

Table 4. Resistor Value Examples for Output Phase Voltage Sensing

PARAMETER

±400-VAC PHASE

±690-VAC PHASE

Resistive divider resistor RAC1

2.0 MΩ

3.48 MΩ

Resistive divider resistor RAC2

2.0 MΩ

3.48 MΩ

Sense resistor RAC3

10.0 kΩ

10.0 kΩ

Resulting current through resistive divider IAC

99.8 µA

99.0 µA

Resulting voltage drop on sense resistor VRAC3

±0.998 V

±0.990 V