ZHCSJ74A December 2018 – January 2020 TCAN4550
PRODUCTION DATA.
Figure 111 and Figure 112 shows the behavior of the 5 V LDO in relationship to ISUP, VSUP, LDO load of 70 mA, CAN bus dominant and ambient temperature. The ISUP current is based upon a 70 mA load on VCCOUT and the CAN bus held dominant for about a total of 120 mA. As can be seen, an ambient temperature of 125°C can cause a thermal shut down event when VSUP reaches 20 V and VCCOUT is providing 70 mA to a load. The load on the CAN bus is 60 Ω. When the CAN bus load is 50 Ω a VSUP of 19 V and ambient temperature of 125 can trigger a thermal shut down event. The reason the curve shows ISUP leveling out to approximately 74.5 mA is due to thermal shut down where the device shuts off the LDO and CAN transceiver. The device cools below TSD leaving thermal shutdown quickly. When the TSD event goes away the device then enters standby mode, turning on the LDO. The 74.5 mA is the 70 mA LDO load and a dominant on the CAN bus in standby mode. This is happening quickly enough that LDO shut off is not seen. If the TSD event is prolonged the current would drop to micro-amps and VCCOUT would be 0 V once the decoupling capacitor discharges.
VCCOUT = 5 V at 70 mA | CAN Bus = Dominant | CAN Load = 60 Ω |
VCCOUT = 5 V at 70 mA | CAN Bus = Dominant | CAN Load = 60 Ω |