JAJSE67C December   2017  – June 2022

PRODUCTION DATA

1. 特長
2. アプリケーション
3. 概要
4. Revision History
5. Device Comparison Table
6. Pin Configuration and Functions
7. Specifications
8. Detailed Description
1. 8.1 Overview
2. 8.2 Functional Block Diagram
3. 8.3 Feature Description
4. 8.4 Device Functional Modes
9. Application and Implementation
1. 9.1 Application Information
2. 9.2 Typical Application
3. 9.3 What To Do and What Not To Do
10. 10Power Supply Recommendations
11. 11Layout
12. 12Device and Documentation Support
13. 13Mechanical, Packaging, and Orderable Information

• DWV|8

### 9.2.2 Detailed Design Procedure

The 100-μA, cross-current requirement at the maximum DC link voltage (400 V) determines that the total impedance of the resistive divider is 4 MΩ. The impedance of the resistive divider is dominated by the top portion (shown exemplary as RX1 and RX2 in Figure 9-1) and the voltage drop across RSNS can be neglected for a moment. The maximum allowed voltage drop per unit resistor is specified as 75 V; therefore, the minimum number of unit resistors in the top portion of the resistive divider is 400 V / 75 V = 6. The calculated unit value is 4 MΩ / 6 = 666 kΩ and the next closest value from the E96 series is 665 kΩ.

RSNS is sized such that the voltage drop across the resistor at the maximum DC link voltage (400 V) equals the linear full-scale range input voltage (VFSR) of the AMC1311, which is 2 V. This voltage is calculated as RSNS = VFSR / (VDC-link, max – VFSR) × RTOP, where RTOP is the total value of the top resistor string (6 × 665 kΩ = 3990 kΩ). RSNS is calculated as 20.05 kΩ and matches a value from the E96 series.

Table 9-2 Resistor Value Example
PARAMETER VALUE
Unit resistor RX 665 kΩ
Number of unit resistors 6
Sense resistor RSNS 20.05 kΩ
Resulting current through resistive divider ICROSS 99.7 μA
Resulting voltage drop across sense resistor 2.000 V
Power dissipated in unit resistor RX 6.6 mW
Total power dissipated in resistive divider 39.9 mW