Other Parts Discussed in Thread: LM2904B, INA240
Hello E2E team,
I have two variants of my ECU design, where we utilize CH7&CH8 to drive either one full H-bridge, or two 1/2-bridges. However, the current shunt configuration is swapped between these two designs. +VBAT is connected to PVDD.
The first variant with one full H-bridge has the current shunt on the low-side, since the lower FETs can be used to protect the shunt in case of short-to-batt condition. 0Ω jumper resistors R1 and R2 would be used to connect SP2/SN2 to this shunt+bridge.
The second variant with two 1/2-bridges utilizes a high-side shunt, since the low-side FETs cannot be used to protect the shunt (both motors are uni-directional brushed motors that connect to GND). Jumper resistors R3 and R4 would be used to connect the same SP2/SN2 pins to this configuration, while depopulating jumper R1, R2 resistors to deactivate the other configuration.
My overall questions are listed below:
- Would this configuration swapping be feasible for the DRV8718? Can the registers be configured separately to have separate implementations like this?
- The electrical characteristics for this shunt amplifier states that the input bias current is approximately I_BIAS = 100µA. Does this bias current have an increased effect on the sleep current of the DRV8718 if utilized on the high-side, since the current will be pulled directly from +VBAT (PVDD)?
- What would be a feasible external op-amp from T, with positive common-mode voltage range (e.g. -V to +V +2), that could be used for high-side current shunt measurement, if this solution is not feasible?
- We currently only use the LM2904B for external op-amp shunt amplification, but this is only feasible for low-side shunt measurements, due to low common-mode voltage range (-V to +V -2).
Regards,
Seid
