Tool/software:
Hi,
I think these questions has been asked in some variation on this forum before, however I cannot find any full description of the solution/what goes on under the hood.
How does the DRV8353S trigger the auto calibration of the current sense amplifier
From the datasheet, I have the following; the auto calibration will occur when VREF passes some threshold.
How does this interact with the gate driver enable pin/device sleep state? The datasheet says that in sleep mode, the sense amplifiers are disabled. Does this mean that the sense amplifier will actually only auto calibrate when VREF and functional mode == operating?
Does this mean that, if the gate driver is powered (VREF is stable for a long period), the auto calibration will be triggered when the gate driver transitions from sleep to operating mode?
From the above description of the auto calibration, it is suggesting that the only triggering event for the auto calibration is VREF matching some threshold, and it is independent of the device functional mode.
How exactly are the SPI registers for calibration supposed to work. The datasheet is not at all clear on their operation and how they should be used.
The datasheet states that the CSA_CAL_X bits should be used to make each amplifier go into calibration mode. How exactly are these registers supposed to be used. It says that the AUTO_CAL bit should be set to 1, and then the CSA_CAL_X bits should be set to rerun the auto calibration routines. This description doesnt make sense with the description of the AUTO_CAL register. 0 is the manual calibration mode, and 1 is the auto calibration mode. For AUTO_CAL, what do these bits mean? Does manual mode mean we are manually triggering CSA_CAL_X after the initial boot-up auto calibration? Or if the previous statement is correct, why is bit == 1 called "auto", when we are manually having to trigger the calibration routine by setting CSA_CAL_X ? What does manual mode actually mean here, there is no other reference to it in the datasheet.
Furthermore, how is CSA_CAL_X supposed to be used? It appears that it needs to be turned on, and then off at some period of time. Without turning this off, the sense amplifier appears to not work and causes an over current event on the HW.
Essentially, I want to know exactly what the sequence is to re-run the amplifier calibration at a known time. What register accesses need to be made, in what order, with what timings, and how does this interact with the rest of the gate driver state.
To do this, simply write high/low to the associated Cal_x register when desired during the switching off period of a phase-X (while the other two phases are active to minimize noise impact on the calibration)