L9305 datasheet(28/107 Pages) STMICROELECTRONICS

28 / 107 page

Integrator low threshold:

The integrator such a threshold corresponds to the integrator value at which the PWM toggles from high to low

and the output driver switches off. At this point, the load current reaches its max peak level. In variable frequency

this level also corresponds to the “F_INTEGRAL” signal at the frequency integrator output. Use this integrator

reading to correctly set the “Fint_Start” parameter.

Integrator high threshold:

The integrator such a threshold corresponds to the integrator value at which the PWM toggles from low to high

and the output driver switches on. At this point, the load current reaches its min peak level. In variable frequency

this level is zero. Use this integrator reading to verify the correct functionality of the variable frequency algorithm.

Integrator minimum level:

The minimum current integrator level. Use this integrator reading to correctly set the “NEGINTLIM” parameter.

Integrator maximum level:

The maximum current integrator level. Use this integrator reading to correctly set the “POSINTLIM” parameter.

6.3.3

Solenoid PWM period feedback

The actual PWM time period, whether it is generated by the internal logic in hardware mode or by the INx pins in

software mode, is internally measured at each PWM rising edge and provided to the MCU for comparison with the

programmed value in register Channel_x.PWMSENSE. It is also checked against the minimum period reference

(Tpwm_min) and maximum period reference (Tpwm_max) values. Should the PWM period fall outside these limits,

the TMOUT flag is set in SPI register Channel_x.PWMSENSE indicating the control loop is working at an unusual

value. If no PWM signal is generated after the maximum reference period (Tpwm_max), the average current is

calculated over Tpwm_max period of time.

The PWM period is provided using 15 bits with 1µs resolution, providing feedback for periods exceeding

Tpwm_max values. The PWM period feedback value is obtained by the formula:

PWMPeriod=Cℎannel_x.PWMSENSE.PWMCodeμs

(1)

•

Tpwm_min = 40 µs → fpwm_max = 25 kHz

•

Tpwm_max = 16.667 ms → fpwm_min = 60 Hz

6.3.4

Out of regulation flag

An out of regulation flag is set when the current controller average error is not zero for a time longer than 8 PWM

periods, where the PWM period is the programmed PWM period in SPI register Channel_x.CTRLCFG. The flag is

independent for each channel and is only available in Hardware Current Control mode.

L9305

Current control drivers

DS12774 - Rev 10

page 28/107

L9305 Datasheet(PDF) 28 Page - STMicroelectronics