RICHTEK RT1720GF

The RT1720 is an over-voltage and over-current protection circuit. It monitors a circuit’s input voltage and current with its adjustable over-voltage and over-current thresholds and drives an external N-MOSFET switch to connect the input to the output voltage only when it is safe. Its wide input voltage range makes it useful for high-voltage applications and in systems that experience large transient voltages and currents, such as automotive, telecom, and industrial applications.

During over-voltage events, the RT1720 quickly reduces the gate drive of the external MOSFET to regulate the output voltage at the level chosen by its external FB resistors. During over-current events, when the load draws excessive current, the RT1720 reduces the gate drive to regulate the output current at the level set by its external current sense resistor. In both cases the output voltage or current is linearly regulated, thermally stressing the MOSFET load switch. However, an externally-adjustable timer limits the duration of MOSFET stress, eventually signaling a fault and then turning off the MOSFET. The RT1720 then periodically restarts operation to test if the fault has cleared. The timer protects the MOSFET while allowing the load circuit to temporarily operate normally through voltage and current surges, such as load dump in automobiles or spinning up disk drives.

The RT1720 features include, open-drain fault and power-good outputs, and a shutdown input. The RT1720 is available in the MSOP-10 package.

• Wide Input Operation Range : 5V to 80V
• Negative Input Voltage Rating to −60V
• Adjustable Output Clamp Voltage
• Adjustable Over-Current Protection
• Programmable Timer for Fault Protection
• Low Shut Down Current
• Internal Charge Pump N-MOSFET Drive
• Fast 80mA MOSFET Shut-off for Overvoltage
• Fault Output Indication

• Automotive Surge Protection
• Hot Swap/Live Insertion
• High-Side Switch for Battery Powered Systems
• Intrinsic Safety Applications