TLE7241E Datasheet, PDF (30/71 Pages) Infineon Technologies AG – Dual Channel Constant Current Control Solenoid Driver

TLE 7241E
Functional Description and Electrical Characteristics
5.5
Current Control
5.5.1 Hysteretic Current Control
The TLE 7241E device uses a hysteretic control method to regulate the solenoid current.
The output transistor is toggled on and off based on the measured value of the solenoid
current. The solenoid current is measured at the pins POSx and NEGx which are
connected to an external current sense resistor. The device calculates an upper and
lower switch point based on the input commands from the microprocessor. The output
transistor is turned on until the upper threshold is reached, and then turned off until the
lower threshold is reached. See Figure 15 for an example of the solenoid current
waveform. In this example, the dither is disabled.
The average switch point
SP_AVG
=
-U----p---p----e---r----s---w----i-t--c---h-----p---t---+-----L----o---w----e----r---s---w-----i-t--c---h-----p---t
2
(3)
is determined by the contents of the average current command register.
The relationship is:
SP_AVG
=
r--e----g---i--s---t-e----r---v---a----l-u---e--
2¹⁰
×
1230
mV
(4)
The hysteresis value can be programmed to a value from 40 mVpp to 110 mVpp in steps
of 10 mVpp.
Upper Switch Point
Hysteresis
Lower Switch Point
Figure 15 Output Current Waveform - No Dither
Data Sheet
30
Rev. 1.1, 2009-01-19