SNVSBJ0A December 2019 – June 2020 LM5170
Figure 20 shows the external and internal configuration for the VIN and VINX pins. Both are rated at 100 Vdc. The VIN pin should be connected either directly to the voltage rail of the HV-Port, or through a small RC filter consisting of 10- to 20-Ω resistor and 0.1-µF to 1-µF bypass capacitor. The internal 330-µA current source supplying the BRKG pin is supplied by the VIN pin.
A cutoff switch connects and disconnects the VIN and VINX pins. When the UVLO pin voltage is greater than 2.5 V, and when the VCC voltage is greater than 8.5 V, the switch is closed and the VINX and VIN pins are connected.
The VINX pin serves as the supply pin for the RAMP generators (see Figure 20 and the Ramp Generator section for details). It is also the high-side terminal of the internal 3-MegΩ pullup resistor for the OVPA pin (see Overvoltage Protection (OVPA, OVPB) for details). Moreover, it serves as the HV-Port voltage sense for internal circuit use during operation.