L9300 datasheet(59/182 Pages) STMICROELECTRONICS

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AVGCURR

Load target current HILOAD = 0

[bit resolution = 1500/2047 = 0.733 mA]

Load target current HILOAD = 1

[bit resolution = 2000/2047 = 0.9770 mA]

2 * 0,733 [mA]

2 * 0,977 [mA]

…

2046

2046 * 0,733 [mA]

2046 * 0,977 [mA]

2047

1500 [mA]

2000 [mA]

INSTCUR is the instantaneous current in the solenoid valve as it is read by the PI control loop input after offset

compensation and calibration; the data is stored in the INSTCURR register with 12 bit signed (2’s complement)

format where the LSB is the ADC full scale (peak current regulation value, 2.25 A or 3 A depending on HILOAD

bit settings) divided by 2047. This data can be used for example in SW mode to verify solenoid current flow

depending on PWM level on INx inputs.

Table 33. Instantaneous current configuration

INSTCURR

Load target current HILOAD = 0

[bit resolution = 2250/2047 = 1.099 mA]

Load target current HILOAD = 1

[bit resolution = 3000/2047 = 1.465 mA]

0 [mA]

± 1

± 1 * 1,099 [mA]

± 1 * 1,465 [mA]

± 2

± 2 * 1,099 [mA]

± 2 * 1,465 [mA]

…

± 2046

± 2046 1,099 [mA]

± 2046 * 1,465 [mA]

± 2047

± 2250 [mA]

± 3000 [mA]

The current sense amplifier input offset is cancelled through the choppering function; the following chopper

parameters can be set through Frequency Control Register:

•

Chopper time sets the toggling time of the chopper function (chopper period is twice this value)

–

If TOFSCHOP = 0 → Offset Toggling Chopper Time = 26 * 125ns

–

If TOFSCHOP = 1 → Offset Toggling Chopper Time = 27 * 125ns

•

Offset Integrator time: sets the integrator time constant used to estimate the recovered high–side/low–side

offsets of current sense circuit. The estimated offset values are available on read in the CSA Offset

Compensation SPI register: the values are stored in the register using 9 bit signed (2’s complement) for

both HS and LS where the LSB weight is

–

Case 1.5 A full scale: 1.5 A * 1.5/213 = 275 µA/LSB

–

Case 2 A full scale: 2 A * 1.5/213 = 367 µA/LSB

–

If TOFSINT = 0 → Offset IntegratorTime = 214 * 125 ns

–

If TOFSINT = 1 → Offset IntegratorTime = 215 * 125 ns

•

Offset Filter time sets the cut off frequency of the hi-pass filter used to extract offset choppered signal

superimposed on the output current.

–

Offset Filter Time = 2N+3 * 125 ns where N is the decimal value stored in the 3 bits.

10.1.1.4

Solenoid PWM period feedback

The driver PWM period, generated by internal logic, is internally measured at each PWM rising edge and provided

to the MCU for comparison with the programmed one in the PWMSENSE SPI register. The PWM period is

provided over 18 bits in order to feedback also periods exceeding TMOUT values; the period value is equal to

N*Tref_PWM where N is the value in the PWMSENSE register and Tref_PWM is 125 ns.

L9300

Solenoid driver

DS12258 - Rev 4

page 59/182

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