ZHCSJ76A March 2018 – April 2019 DRV8343-Q1
PRODUCTION DATA.
The current sense amplifiers on the DRV8343-Q1 SPI device can be configured to amplify the voltage across the external low-side MOSFET VDS. This configuration lets the external controller measure the voltage drop across the MOSFET RDS(on) without the shunt resistor and then calculate the half-bridge current level. This setting is not available in the H/W device.
To enable this mode set the CSA_FET bit to 1. The positive input of the amplifier is then internally connected to the DLx pin with an internal clamp to prevent high voltage on the DLx pin from damaging the sense amplifier inputs. During this mode of operation, the SPx pins should stay disconnected. When the CSA_FET bit is set to 1, the negative reference for the low-side VDS monitor is automatically set to the SNx pin, regardless of the state of the state of the LS_REF bit. This setting is implemented to prevent disabling of the low-side VDS monitor.
If the system operates in MOSFET VDS current sense mode, route the DLx and SNx pins with Kelvin connections across the drain and source of the external low-side MOSFETs.
When operating in MOSFET VDS current sense mode, the amplifier is enabled at the end of the tDRIVE time. At this time, the amplifier input is connected to the DLx pin, and the SOx output is valid. When the low-side MOSFET receives a signal to turn off, the amplifier inputs, SPx and SNx, are shorted together internally.