L9300_V01 datasheet(53/178 Pages) STMICROELECTRONICS

53 / 178 page

•

KP Proportional portion of the loop gain:

–

KP = 2N+1

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

Note:

Default values in KGAINS register are set in order to operate properly with typical load values in fixed frequency

mode.

For variable frequency mode only the following parameters can be used to control integrator saturation of PI loop.

In fixed frequency mode integrator saturation limits are internally computed and the above parameters are not

used.

•

INTLIMVAL Integrator Saturation Limit. Its value is:

–

2N+7 if N≤13, where N is the decimal value stored in the 4 bits

–

220 if N>13

where N is the decimal value stored in the 4 bits of the INTGLIM register.

•

TRINTLIMVAL Transient Integrator Saturation Limit: it is the integrator saturation limit during set point

change transient response; transient response is defined as the time needed from set point change to

reach zero error in the sensed current.

–

0xxx → TRINTLIMVAL = 2-N * INTLIMVAL

–

1xxx → TRINTLIMVAL = 1

where N is the decimal value stored in the 3 less significant bits of the INTGLIM register.

In variable frequency mode additional parameters can be configured through the Frequency Control Register to

tune the PI coefficients of the frequency control loop:

•

KFI Integral portion of the frequency control loop gain: it is available through 3 bits as 2-N

•

KFP Proportional portion of the frequency control loop gain: it is available through 3 bits as 2-N

•

FCIL: Frequency Control Integrator Limit: it enables saturation of the integrator in the frequency control

loop. Saturation limit is internally computed and cannot be programmed.

Full On Mode

Each driver can be programmed to work in full on mode. If the bit FULL_ON_x is set to 1 (default is 0) the driver is

kept on continuously, until the bit is programmed to 0 or a fault occurs.

10.1.1.2

Software current control

In this configuration, SW_cntr_x = 1, the device works as simple driver and provides the load current

measurement to the microcontroller by SPI. In that way the microcontroller can close the current control loop

acting directly on the parallel input of the channels.

In software mode a toggling of INx longer than INx_in_ft is used to trigger the measurement of the mean current

flowing in the load; average current is calculated and updated into the dedicated AVGCUR SPI register at the end

of a valid PWM input signal (see Figure 32 / Figure 33). To properly turn on the driver a command duration longer

than LOADx_Ton_res has to be provided. (the same for the turning-off phase).

In case the INx input command is stucked, the average is evaluated till timeout set to 133334*tref_PWM, where

tref_PWM = 125 ns, and a warning flag TMOUT is set in PWMSENSE register. At TMOUT the average current

and PWM code calculations are restarted automatically.

L9300

Valve drivers

DS12258 - Rev 5

page 53/178

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