Figure 7-1 shows a simplified schematic of a full-bridge motor drive that uses an AMC0106M25 to sense the motor current. The current flowing through an external shunt resistor RSHUNT produces a voltage drop that is sensed by the AMC0106M25. The AMC0106M25 digitizes the analog input signal on the high-side and transfers the data across the isolation barrier to the low-side. The device then outputs the digital bitstream on the DOUT pin that is synchronized to the clock applied to the CLKIN pin. The digital bitstream is processed by a low-pass digital filter in a micro control unit (MCU) or FPGA.

The 48V DC link voltage in this application is sensed by an AMC0136 isolated modulator.

Figure 7-1 Using the AMC0106M25 for Current Sensing in a Full-Bridge 48V Motor Driver Design

The high-side power supply (AVDD) is generated from a bootstrap circuit (R4, D1, C2). The low-side supply is shared with circuitry in the signal domain. Use the optional 49.9Ω resistor on the DOUT pin for line-termination to improve signal integrity on the receiving end.

The galvanic isolation barrier and high common-mode transient immunity (CMTI) of the AMC0106M25 provide reliable and accurate operation even in high-noise environments.