ZHCSL09C April 2020 – December 2020 LM7480-Q1
PRODUCTION DATA
Figure 9-5 shows the implementation of Dual OR-ing with Inrush Current Limiting, overvoltage Protection and power path ON/OFF control. The input side SMBJ36CA TVS across the ideal diodes is required for ISO7637 Pulse 1 transient suppression to limit the input voltage within the device max voltage rating of –65V.
R1 and R2 are the programming resistors for over voltage protection (OVP) threshold. When the voltage at OV pin exceeds OV cut-off reference threshold then the HGATE driver turns OFF the FET Q3, disconnecting the power path and protecting the downstream load. HGATE goes high once the OVP pin voltage goes below the OVP falling hysteresis threshold. Use 0.1-μF to 1-μF capacitor across VS to CAP pins of the LM7480x-Q1. This is the charge pump capacitor and acts as the supply for both the DGATE and HGATE driver stages. The DGATE driver of the LM7480x-Q1 is equipped with 20-mA peak source current and 2.6-A peak sink current capability resulting in fast and efficient transient responses during the ISO16750 or LV124 short interruptions as well as AC superimpose testing.
Pull EN low during the sleep/standby mode. With EN low, both the DGATE and HGATE drivers are pulled low turning OFF both the power FETs. VOUT1 gets disconnected from the input supply rail reducing the system IQ. VOUT2 is gets power through the body diode of the MOSFET Q2 and this supply can be utilized for always ON loads. The LM7480x-Q1 draws a 2.87-μA (typ) current during this mode.