Infineon Squib Driver

Accordingly, an identical steady-state voltage can be obtained in both operation modes i. Starting from the circuit shown in Fig. As a consequence, only the typically very low resistance of the controllable energy-coupling element limits the speed at which the charge can flow to the control electrode of the power transistor.

It should further be mentioned that the advantages of the present invention can be reached using a combination of the pre-charge capacitance and the controllable energy-coupling element. With respect to the graphical representation of Fig. Typically, one field-effect transistor of the pair of field-effect transistors is placed at each side of the squib. Furthermore, the controllable energy-coupling element can be a switch or a controllable buffer. The guaranteed closed-loop voltage provided by the second voltage source is needed for new-generation squibs and is useful for implementing the diagnosis stand-by mode.

Also, the first voltage regulator may be replaced by a charging circuit as described with respect to power switch circuit of Fig. The equivalent circuit of Fig. If the multiplexer is switched to connect the output of the voltage-providing circuit to the capacitance, the first current source is deactivated. Also, it should be noted that the pre-charge capacitance constitutes a safety mechanism.

The Curse of the Infineon TPM Driver and BitLocker

Accordingly, there is still a possibility that a malfunction is not detected. For example, the fixed potential may be the reference potential. Furthermore, the voltage follower can be adapted to scale the reference voltage, which can, for example, be achieved by an appropriate circuit comprising an operational amplifier. Furthermore, it is assumed that a source electrode S of the power transistor is connected to the load comprising a resistive and possibly also a capacitive component. It should also be noted that in another embodiment the present invention comprises a load capacitance connected between the second terminal of the power transistor and the reference potential.

Modern automotive security systems require a very fast reaction time. Furthermore, the second current source is preferably activated for a predetermined period of time after switching the circuit of Fig. The charger circuit may further comprise a diode connected between a supply potential of the charger charging circuit.

Infineon squib driverInfineon squib driverInfineon squib driverInfineon squib driver

Furthermore, the diagnostic of the presence of the pre-charge capacitance can be performed at every startup wherein a startup is a transition from the stand-by mode to the firing mode. Accordingly, the pre-charge capacitance can help to stabilize the potential at the control electrode of the power transistor at a fixed value. The security feature can be supported by a control circuit adapted to close the second switch when the energy-coupling element is inactive e. Using an operational amplifier is particularly advantageous as the operational amplifier can be implemented easily and provides a very high accuracy of the output voltage. In such security-related systems a periodic check of the presence of the reservoir capacitance has to be performed.

This allows a fast startup as the current is not limited in stand-by mode. Additionally, some logic interfaces manage the transitions from stand-by mode to firing mode and vice versa. So, the power transistor can even be activated put into the conducting state in the absence of a sufficient supply potential for the charging circuit. In other words, the switch or buffer can also be considered a controllable energy-coupling element. This high impedance results in a very good decoupling between the control terminal of the power transistor and the charging circuit, and accordingly helps to improve stability.

For example, the squib module may comprise a series connection of a high-side switch e. The usual way to check the presence of a capacitor is to sink a current from the capacitor and to monitor the slope of the voltage during discharge.

Infineon squib driver

The Curse of the Infineon TPM Driver and BitLocker - The Billable Life

In particular, control logic may also control one or more self diagnosis steps. This allows a simple identification of any defective elements. However, in another embodiment the resistor may be omitted.

In order to enable such a test, it is just necessary to have a certain regulated voltage at the input of the squib drivers circuitry, i. This voltage was found to be useful to implement some kind of diagnostic on the squib driver circuit. The combination of these two elements allows both a high degree of stability and a sufficiently fast switching speed. Furthermore, aarp alamo additional driver in the firing mode of operation the N-type channel field-effect transistor may conduct a high current through its load path.

Also, some characteristics of the inventive circuit will be derived. For that reason, the pre-charged capacitor has to be really huge order of magnitude of some mF.

Furthermore, the voltage applied to the source of the N-type channel field-effect transistor can be considered to be a safety feature, as will be outlined in detail below. In other words, the auxiliary voltage source may sense the voltage at the second terminal of the power transistor and comprise a closed regulator loop.

Furthermore, both the buffer and the switch have a sufficiently small resistance so that they do not severely degrade the transient response of the power switch circuit. In other words, the charging circuit may comprise an operational amplifier, the output of which is coupled with the pre-charge capacitance. In other words, the buffer and the parasitic resistance in Fig. Furthermore, it should be noted that some circuits intended to define and limit the amount of current flowing through the series connection have already been proposed and studied.

This can help to relax the requirements with respect to the charging circuit and reduce the overall current consumption. The output the source terminal of the additional power element is driven in a source-follower configuration, wherein the source voltage is determined directly by the value of the gate voltage. Besides, it should be noted that the circuit of Fig. For example, the firing squib and the driver circuit may be connected as already described with reference to Fig.

However, such a known solution requires additional wiring. In other words, in a stand-by mode, preferably the second voltage regulator is active. The energy-coupling element is further preferably adapted to isolate the pre-charge capacitance from the control electrode of the power transistor in the non-conducting state. Otherwise, if the voltage monitor detects a high absolute or relative voltage change e.

The first voltage regulator may, for example, comprise any voltage regulation means. Overall, using the inventive approach the order of the system is reduced to a second-order system. If the pre-charge capacitance is charged i.

Infineon squib driver

Certain diagnostic functions can be performed directly on the squib drivers but also on the external power switching element itself in order to check the integrity of the system. The presence of a constant voltage for the squib explosion circuitry was found to be useful to check whether squibs are functional or not.

The microcontroller can change from a first state idle or stand-by to the second state firing mode and vice versa. Such tests can be performed without the power transistor being switched on. The second current source is preferably adapted to discharge the pre-charge capacitance by sinking a second current if the second current source is activated. In the conducting state of the controllable energy-coupling element, the charge of the pre-charge capacitance can be transferred to the control electrode of the power transistor very fast. The complete timing is specified in the diagram of Fig.