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 THE L9380 TRIPLE CHARGE PUMP This triple high side power MOSFET driver features all necessary control and protection functions to drive three n-channel power MOS transistors operating as highside switches in automotive electronic control units. The key application field is relays replacement in systems where high current loads, usually motors with nominal currents of about 40A connected to ground, has to be switched. An n-channel MOSFET in highside configuration needs a gate driving voltage higher than the supply voltage. In the case of the L9380 it is generated by means of a charge pump with integrated charge transfer capacitors and one external charge storage capacitor. The charge pump of the L9380 is dimensioned to load a capacitor of 33nF in less than 20ms up to 8V above the supply voltage. In case the supply voltage exceeds values of 25V (typical) the charge pump oscillation is stopped. Two out of three outputs of the L9380 provide drain to source voltage sensing. When the activation threshold, set by external resistors is exceeded, programmable shut-off delay is activated. Positive ISO-pulses at drain, gate and source are internally clamped to less than 60V. A typical automotive system where the L9380 is used is the Traction Control System (TCS), a combination of Anti-Lock Braking System (ABS) and Anti-Slip Control (ASC). For redundancy reasons in Traction Control Systems two DC motors are needed to drive the pumps for the hydraulic circulation. Both motors are controlled one at a time by one single power switch in highside configuration. In addition, the third output of the L9380 is used to drive a power MOSFET for common reverse battery protection of all eight valves needed in Traction Control Systems.  |
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