78M6610+PSU
Hardware Design Guidelines
APPLICATION NOTE
AN_6610_107
July 2012
Rev 0 1
1 Introduction
This application note describes hardware and system design guidelines for incorporating precision power
monitoring of better than 1% accuracy into AC/DC power supplies using the 78M6610+PSU. For real-time
embedded measurement of the AC input power in a power supply, there are three possible sensor
locations:
1. Measuring behind the EMI filtering circuit (recommended).
• Balanced approach to component cost and calibration cost made possible by real-time XY
capacitor compensation and data processing included with the 78M6610+PSU.
2. Measuring right at the AC inlet (supported).
• Size (and cost) of isolated sensors often prohibitive.
3. Measuring the half-wave rectified signal after the bridge (not covered).
• Not recommended for precision accuracy across entire operating range due to extensive offset
and gain calibration times.
The following topics are discussed in more detail:
• Recommended Sensor Configuration
- Powering the 78M6610+PSU
- Line Voltage Resistor Dividers
- Current Shunt Selection
• Alternative Sensor Configuration
- Current Transformers
• Device Configuration
- Clock Circuitry
- Reset Circuitry
- Connecting 5V Devices
- Driving External Loads
- Serial Interfaces
• PCB Layout Guidelines
