The high-side gate-drive voltage supply is created using a doubler charge pump that operates from the VM and VDRAIN voltage supply inputs. The charge pump allows the gate driver to correctly bias the high-side MOSFET gate with respect to the source across a wide input supply voltage range. The charge pump is regulated to keep a fixed output voltage of VVDRAIN + 10.5 V and supports an average output current of 25 mA. When VVM is less than 12 V, the charge pump operates in full doubler mode and generates VVCP = 2 × VVM – 1.5 V with respect to VVDRAIN when unloaded. The charge pump is continuously monitored for undervoltage to prevent under-driven MOSFET conditions.
The charge pump requires a X5R or X7R, 1-µF, 16-V ceramic capacitor between the VDRAIN and VCP pins to act as the storage capacitor. Additionally, a X5R or X7R, 47-nF, VDRAIN-rated ceramic capacitor is required between the CPH and CPL pins to act as the flying capacitor.
The low-side gate drive voltage is created using a linear regulator that operates from the VM voltage supply input. The VGLS linear regulator allows the gate driver to correctly bias the low-side MOSFET gate with respect to ground. The VGLS linear regulator output is fixed at 14.5 V and further regulated to 11-V on the GLx outputs during operation. The VGLS regulator supports an output current of 25 mA. The VGLS linear regulator is monitored for undervoltage to prevent under driver MOSFET conditions. The VGLS linear regulator requires a X5R or X7R, 1-µF, 16-V ceramic capacitor between VGLS and GND.
Since the charge pump output is regulated to VVDRAIN + 10.5 V this allows for VM to be supplied either directly from the high voltage motor supply (up to 75 V) to support a single supply system or from a low voltage gate driver power supply derived from a switching or linear regulator to improve the device efficiency or utilize an externally available power supply. On the DRV8350R and DRV8353R devices the integrated buck regulator can be used to create the efficient low voltage supply for VM without the need for an additional regulator. Figure 30 and Figure 31 show examples of the DRV835x configured in either single supply or dual supply configuration.