L9300 datasheet(52/178 Pages) STMICROELECTRONICS

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One particular condition is implemented in case number of dither step is set to 0: a single positive and negative

pulse is generated with amplitude provided by amplitude parameter.

Through a dedicated bit in the CONFIGURATION register it is possible to enable dither synchronization feature:

once this bit is set the dither waveform is changed to start the new dither step synchronously to solenoid PWM

signal. Synchronization can be implemented in two ways depending on the settings of SYNC_TYPE bit in

CONFIGURATION register: if the SYNC_TYPE is set to 0 the dither step synchronization is done at each change

in the step value itself otherwise the synchronization is performed at the start of each dither period.

In case of dither step synchronization at each dither step is selected (SYNC_TYPE = 0) the dither step duration is

increased with respect to the programmed value to include an integer number of PWM periods; the exact formula

is given by:

Tstep_sync = ceil (((1 + (M+1)*2N)*tref_dth)/Tpwm)*Tpwm

The resulting dither period is 4 times the programmed Dither current step number bits of DITHPGM register

multiplied by T_step_sync.

Dither Period = 4 * Nstep * Tstep_sync

In case of dither period synchronization at each dither period is selected (SYNC_TYPE = 1) only the first dither

step duration is increased with respect to the programmed value in order to have a resulting dither period

including an integer number of PWM periods; the Tstep_duration formula is unchanged with respect to the

condition of synchronization disabled, while the resulting dither period is given by:

Dither Period = ceil (4*Nstep*Tstep/TPWM)*TPWM

Where Nstep is the programmed Dither current step number in DITHPGM register.

Figure 29. Dither functionality

GADG1807171117PS

HW Current Control Loop Configuration

When HW current feedback mode is selected, the solenoid current is controlled through a PI algorithm. In order to

tune the transient response and settling time of the loop that may vary changing the load configuration, a sub set

of control loop parameters are available through SPI registers.

For both variable and fixed frequency control the following parameters can be changed.

•

KI Integral portion of the loopgain:

–

In variable frequency mode it is based on the formula KI = 2-(N+3)

–

In fixed frequency mode it is based on the formula KI = 2-(N+5)

where N is the decimal value stored in the 3 bits of the KGAINS register.

L9300

Valve drivers

DS12258 - Rev 5

page 52/178

L9300 датащи(PDF) 52 Page - STMicroelectronics