The TPIC44H01 is a four channel high-side pre-FET driver which provides serial or parallel input interface to control four external NMOS power FETs. It is designed for use in low frequency switching applications for resistive or inductive loads, including solenoids and incandescent bulbs.
Each channel has over-current, short-to-ground, and open-load detection that is flagged through the FLT\ pin and distinguished through the serial interface. Over-current thresholds are set through the V(PK_x) and V(COMP1-4) pins. Short-to-ground and open-load thresholds are set internally to approximately 2.5 V. The AR_ENBL pin is used to define the operation of the device during a fault condition, allowing the outputs to either latch off or to enter a low duty cycle, auto-retry mode. An over-voltage lockout circuit on V(PWR) protects the device and the external FETs. A low current sleep state mode is provided to allow the TPIC44H01 to be used in applications where V(PWR) is connected directly to the battery. An internal charge pump allows the use of N-channel FETs for high-side drive applications, while current-limit gate drive provides slope control for reduced RFI.
By having the unique ability to develop a dynamic over-current threshold, the TPIC44H01 can be used to drive incandescent bulbs with long inrush currents without falsely flagging a fault. Likewise, the user can select an internally set over-current threshold of ~1.25 V by pulling the respective V(COMP1-4) pin to VCC.
The 8-bit serial peripheral interface (SPI) allows the user to command any of the four outputs on or off, to program one of eight possible open-load, over-current, and short-load fault deglitch timer settings, and to engage the sleep state. Data is clocked into the SDI pin on the rising edge of SCLK and clocked out of the SDO pin on the SCLK falling edge. The serial input bits are logic OR'ed with the IN1-IN4 parallel inputs pins. The serial interface is also used to read normal-load, open-load, over-current, and short-to-ground conditions for each channel. Over-voltage lockout can be detected when the FLT\ pin is low and no bits are set in the SDO register. Multiple TPIC44H01 devices may be cascaded together using the serial interface to further reduce I/O lines from the host controller.
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