This reference design demonstrates a unique approach for extending current measurement range using a single shunt and voltage measurement AMC1304Mx5 isolated delta-sigma (ΔΣ) modulator. With careful selection of a low-value shunt resistor that minimizes power dissipation, a front-end amplifier with low noise and by introducing two gain paths, both upper and lower current limit is extended. Accuracy of < ±0.5 % for both current and voltage measurement is achieved by interfacing the modulator output to AM437x host processor which performs the Sinc3 filtering.
Features
- Single-phase voltage and current measurement (shunt based) using isolated delta-sigma modulator (AMC1304Mx5)
- Measurement accuracy:
- AC current: < ± 0.5% from 0.1 A to 40 A (or 60 A) for In = 1 A
- AC voltage: < ± 0.5% from 10 V to 300 V
- AFE interfaced to host MCU (AM437x Sitara™ ARM® Cortex®-A9 processor) which performs Sinc3 digital filtering using PRU-ICSS
- Onboard isolated ± 2.5-V and +5.0-V Power supply for AMC1304Mx5 and OPA188 using transformer driver and LDOs
- Designed to work from 0.1 A to 60 A (In = 1 A) and can be extended for wider range (In = 5 A) by changing shunt and gain values.