The MAX4838–MAX4842 are overvoltage protection ICs that protect low-voltage systems against voltages of up to 28V. If the input voltage exceeds the overvoltage trip level, the MAX4838–MAX4842 turn off the low-cost external n-channel FET(s) to prevent damage to the protected components. An internal charge pump eliminates the need for external capacitors and drives the FET gate for a simple, robust solution. The MAX4838/MAX4839 have a 7.4V overvoltage threshold, and the MAX4840/MAX4841EXT have a 5.8V overvoltage threshold. The MAX4842 has a 4.7V overvoltage threshold. The MAX4838–MAX4841EXT have an undervoltage lockout (UVLO) threshold of 3.25V while the MAX4842 has a UVLO of 3.0V. In addition to the single FET configuration, the devices can be configured with back-to-back external FETs to prevent currents from being back-driven into the adapter. On power-up, the device waits for 50ms before driving GATE high. Active-low FLAG is held low for an additional 50ms after GATE goes high before deasserting. The MAX4838/MAX4840/MAX4842 have an open-drain active-low FLAG output, and the MAX4839/MAX4841EXT have a pushpull FLAG output. The active-low FLAG output asserts immediately to an overvoltage fault. Additional features include a 15kV ESD-protected input (when bypassed with a 1μF capacitor) and a shutdown pin (active-low EN) to turn off the device (MAX4838/MAX4840/MAX4842). All devices are offered in a small 6-pin SC70 package and are specified for operation from -40°C to +85°C. 
Feature
 
 
  
  - Overvoltage Protection Up to 28V 
 
  - Preset 7.4V, 5.8V, or 4.7V Overvoltage Trip Level 
 
  - Drive Low-Cost NMOS FET 
 
  - Internal 50ms Startup Delay 
 
  - Internal Charge Pump 
 
  - Undervoltage Lockout 
 
  - 15kV ESD-Protected Input 
 
  - Voltage Fault active-low FLAG Indicator 
 
  - 6-Pin SC70 Package 
 
 
 
  
Applications
 
 
 
  - Cell Phones
 
  - Digital Still Cameras
 
  - MP3 Players
 
  - PDAs and Palmtop Devices