A configurable high-side/low-side driver with fast and equalized switching delay

A configurable high-side/low-side driver (HSD/LSD) for inductive loads is presented. The operating mode of this driver depends just upon external connection. The circuit incorporates improved protection circuitry using modified Zener diodes. These diodes are isolated, allowing large negative voltages at source and gate of the switch device. Drain-gate clamping turned out to be most suitable. Together with an isolated output stage of the driving circuit, this results in large negative source and gate voltages for the HSD configuration, leading to faster switch-off. After a qualitative description of the switching behavior, equations for the switching delay are derived which confirm fast and similar HSD/LSD switching times for the proposed driver. Experimental results in a 0.35 μm BiCMOS technology show that the gate can drop as low as -28 V in the high-side configuration. In the low-side configuration, the drain can rise as high as 45 V. Delay measurements for varying clamping levels and inductance values are presented. The configurable driver shows an excellent behavior both for high-side and low-side in an H-bridge motor driver.