The MAX17616/MAX17616A offers highly versatile and programmable protection boundaries for systems against input voltage faults and output overcurrent faults. Input-voltage faults (with positive polarity) are protected up to +80V (without Reverse Current Protection)/+75V (with Reverse Current Protection), by an internal nFET featuring low ON-resistance (20mΩ typ). The devices feature a programmable undervoltage-lockout (UVLO) thresholds by using external voltage-dividers. The MAX17616 features a programmable overvoltage-lockout (OVLO) while MAX17616A offers a programmable output voltage clamp function through the OVFB pin that features an output voltage limiting regulation during input transient surge events. Input undervoltage and overvoltage protection (MAX17616)/output voltage clamp function (MAX17616A) can be programmed across the entire 3V to 80V operating range.
Input reverse-polarity protection is realized using an external nFET that is controlled by the devices. The magnitude of reverse-polarity voltage protection is dependent on the operating load-bus voltage (VOUT
) and the voltage-blocking capability of the external nFET. For example, for protection down to a -55V input range with VOUT = 30V, an external nFET rated at 85V is needed. The external nFET is also needed for the optional reverse-current protection. When used with a Reverse Protection external nFET (Q1), the devices prevent reverse current flow from load to source by turning off Q1. The reverse current thresholds and forward bias characteristics of the reverse current protection feature are tuned to achieve an ideal diode function suited for OR-ing and Power Multiplexer applications. If reverse polarity protection and reverse-current protection are not needed, SN and GN pins must be connected to IN. The devices are tolerant against accidental output reverse-polarity application due to incorrect wiring across the output terminals.
The current limit of the devices is programmed by connecting a resistor from the SETI pin to GND. The current limit can be programmed from 0.7A to 7.0A. When the current through the devices reaches or exceeds the set current limit, the resistance of the internal nFET is modulated to limit the current. The devices offer three current-limit behavioral modes: Continuous, Auto-retry, and Latch-off modes. In addition, the devices allow programmable startup inrush current limit during startup events, to prevent inrush current from limited power sources flowing into capacitive or negative impedance output loads.
The IMON pin presents a current proportional to the device current under normal operation. Together with the IMON resistor (between IMON and GND), the IMON pin presents a voltage that is proportional to the device current. This voltage can be read by a monitoring system to record the instantaneous current of the device. Place a 100nF ceramic capacitor from IMON to GND.
The device can be turned ON or OFF by enabling input EN by a controller supervisory system. This allows the controller supervisory system to Turn ON or OFF the power delivery to connected loads.
The devices offer loss-of-ground protection where it safely turns OFF the device operation during a loss-of-ground fault event, i.e., when the safety ground fuse opens in a redundant safety application.
The devices offer a status announcement signal (SMBALERT) to indicate operational and fault signals. The devices also offer a Power Good Signal (PGOOD/TJ) that may be used by a supervisory system to enable/disable the downstream loads. PGOOD/TJ is an open drain pin and requires an external pullup resistor to the appropriate system interface.
The devices offer a programmable output undervoltage sense threshold that governs the restart response after the output voltage drops below the OUTUV Rising threshold. The device also offers internal thermal shutdown protection against excessive power dissipation.
The devices offer a PMBus compatible Serial Peripheral Interface, with commands to control the device operation and observe system level parameters.
APPLICATIONS
- Input Voltage and Output Overcurrent Protections
- Loss of Ground Protection
- Surge Protection
