TLE82453-3SA_15 Datasheet, PDF (28/71 Pages) Infineon Technologies AG – 3 Channel High-Side and Low-Side Linear Solenoid Driver IC

TLE82453-3SA
Current Control
8.4
Sense Resistor
The current sense resistor is integrated into the device. The initial error and the temperature drift of this resistor
are measured and trimmed during the device manufacturing process.The internal protection circuits are built in a
way, that repeated shorts to VBAT/GND will not destroy the internal shunt.
8.5
Current Controller
The current controller regulates the load current by alternatively turning on the drive switch and the recirculation
switch. The on time of the drive switch is determined by the integrated PWM period controller. The off time of the
transistor is determined by the average current controller. When the average load current over the current PWM
period is equal to the setpoint during freewheeling, the drive transistor is turned on again and the next PWM cycle
is started.
Output Stage
State
Load
Current
“on time”
“off time”
I _setpoint
Error
Integrator
threshold
Current control
w av ef orm. v s d
Figure 10 Controller waveforms
The controller includes an integrator which integrates the difference between the average load current and the
setpoint over the time duration of the PWM cycle. At the start of a PWM cycle, the driving FET is turned on and
the recirculation FET is turned off. In this phase of operation, the load current will increase. When the value of the
error integrator exceeds the integrator threshold, the driving FET is turned off and the recirculation FET is turned
on. The load current will decrease in this phase of operation. The integrator threshold is adjusted automatically by
the internal PWM period controller until the desired PWM period is reached. When the error integrator decreases
to 0, the recirculation FET is turned off and the driving FET is turned on to start the next PWM cycle.
The integrator can be automatically limited by the device after a change in setpoint by setting the Auto-Limit bit in
the SETPOINT register. The device will limit the integrator output to a small value (+/- 20d) during the setpoint
change and then automatically revert back to the normal integrator limit values after the setpoint change has been
achieved when this bit is set. The bit remains set until changed, or a reset occurs.
A “Regulator Error” fault bit in the DIAGNOSIS register is set when the programmed setpoint current is not reached
after 8 PWM cycles after the SETPOINT register is written.
Data Sheet
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28
Rev 1.0, 2015-03-27