Bidirectional H-Bridge Monitoring with ADC-Friendly Differential Output

The dual outputs of the LTC6103 can be used individually to provide overload detection, and/or may be taken as a differential pair to provide a bidirectional signal to an analog-to-digital converter (ADC) for example. Figure 3 shows a typical circuit for a generic H-bridge application. The power devices may be complementary MOSFETs, pure N-MOSFETs, or other switching devices. When the bridge drives the load (a motor assumed in the example shown), one of the LTC6103 outputs rises above ground, while the other remains pulled down to ground, thereby forming an accurate bidirectional differential output with a common mode voltage that never falls below ground. The selection of output resistance (4.99k in the example) can be scaled to satisfy the source-impedance requirement of any ADC.