MC33937 Datasheet, PDF (40/48 Pages) Freescale Semiconductor, Inc – Three Phase Field Effect Transistor Pre-driver

FUNCTIONAL DEVICE OPERATION
INITIALIZATION REQUIREMENTS
IC INITIALIZATION
This process flow will initialize the IC and its software environment.
1. Apply power (V_SYS) to module
2. Remove RST (RST goes high, EN1 and EN2 are still low)
2.1. When RST rises above the threshold, the device will power-up. The charge pump (if configured) will start, allow V_DD
and V_LS to stabilize.
3. Initialize registers
3.1. Clear all interrupt status flags (send CINT0 and CINT1)
3.2. Initialize MASK register by sending 0010 xxxx or 0011 xxxx to mask out unwanted interrupts.
3.3. Set desired dead time either by commanding zero dead time or calibrating the dead time.
3.4. Send MODE command with desired bits, and also the Lock bit. e.g. 01000001. This prevents further mode changes.
4. Bring EN1 & EN2 high
5. Initialize the outputs
5.1. Command all Px_HS to logic 1 (High Side OFF)
5.2. Command all Px_LS to logic 1 (commanding Low Side ON). The input must transition from low to high after EN1 and
EN2 have gone high.
5.3. Wait for the bootstrap capacitors to charge (about 1us typically)
5.4. Command all Px_LS to logic 0 (command Low Side OFF)
5.5. Command all Px_HS to logic 0 (command High Side ON)
5.6. Command all Px_HS to logic 1 (command High Side OFF)
The device is now ready for normal operation.
INTERRUPT HANDLER
When an interrupt occurs, the general procedure is to send NULL0 and NULL1 commands to determine what happened, take
corrective action (if needed), clear the fault and return.
Because the return value from an SPI command is actually returned in the subsequent message, main-loop software that tries
to read SR1, SR2 or SR3, may experience an interrupt between sending the SPI command and the subsequent read. Thus if
these registers are to be read, special care must be taken in the software to ensure that the correct results are being interpreted.
33937A
40
Analog Integrated Circuit Device Data
Freescale Semiconductor