The MAX4970/MAX4971/MAX4972 family of overvoltage protection devices features a low 40mΩ (typ) R_ON internal FET and protect low-voltage systems against voltage faults up to +28V. These devices also drive an optional external pFET to protect against reverse-polarity input voltages. When the input voltage exceeds the overvoltage threshold, the internal FET is turned off to prevent damage to the protected components.

All switches feature a 2.3A (min) current-limit protection. During a short-circuit occurrence, the device operates in an autoretry mode where the internal MOSFET is turned on to check if the fault has been removed. The autoretry interval time is 15ms, and if the fault is removed, the MOSFET remains on.

The MAX4970/MAX4971/MAX4972 feature an enable input (active-low EN) that controls the operation of the internal nFET as well as the optional external pFET. The use of active-low EN allows the external pFET to block reverse voltages independent of any signal present at the output.

The overvoltage thresholds (OVLO) are preset to 4.65V (MAX4972), 5.8V (MAX4970), or 6.35V (MAX4971). The undervoltage thresholds (UVLO) are preset to 2.45V. When the input voltage drops below the UVLO, the devices enter a low-current standby mode.