In the figure:
Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.
In normal operation the voltage in to terminal 12 is within normal operating range, VGate
In protective operation, the voltage VIN increases over the normal operating range. When VGate
In applications, such as a motor vehicle, circuitry often has a maximum voltage which is lower than possible peaks. For example, power control units (PCU) often have a maximum voltage of 40V. During a load dump, the voltages applied to the PCU may far exceed this maximum voltage threshold, and the circuit of
During the aforementioned load dump, transistor T2 is activated when VIN reaches predetermined set threshold value, such as 30V. The activation of transistor T2 causes transistor T1 to be turned off. The PCU current, approximately 300 mA generates a voltage drop across the resistors R1 through R4. If resistors R1 through R4 are each approximately 40 Ohm resistors, the voltage drop is approximately 3V.
This enables the current load dump protection circuit to be implemented in scenarios where voltages reach values higher than the 40 V threshold voltage without harming the PCU.
This circuit can be adjusted by component selection to switch on at any required voltage, have a predetermined voltage drop based on current draw and clamp the output voltage to any safe maximum voltage.
An additional use of the circuit described above is to provide an output voltage that is clamped under a set value, such as 28V. In many vehicles, the PCU has a threshold voltage of 28V, causing the PCU to activate a pump motor FET.
The many features and advantages of the invention are apparent from the detailed specification. Thus, the appended claims are to cover all such features and advantages of the invention that fall within the true spirit and scope of the invention. Furthermore, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described. Accordingly, appropriate modifications and equivalents may be included within the scope of the invention.
Although this invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made which clearly fall within the scope of the invention.