AMS1117-3.3

The AMS1117-3.3 is a 1A low-dropout voltage regulator from Advanced Monolithic Systems (AMS), providing a fixed 3.3V output with guaranteed maximum dropout voltage of 1.3V at full 1A load. The output voltage is trimmed to +/-2% accuracy using on-chip precision trimming. Built-in thermal shutdown and current limiting protect the device under overload conditions. The AMS1117-3.3 is pin-compatible with the industry-standard 1117 family, making it a drop-in replacement for LM1117-3.3, LD1117-3.3, and other 1117-series devices in SOT-223, TO-252, and SOT-89 packages.

The AMS1117-3.3 uses a PNP pass transistor to achieve low dropout voltage. An error amplifier compares a divided-down version of the output voltage with an internal bandgap reference trimmed to +/-1% accuracy. The amplifier drives the PNP pass element to maintain 3.3V at the output. When the input-output differential falls below the dropout voltage, the PNP saturates and the output tracks the input minus the dropout. The on-chip thermal shutdown circuit disables the output when junction temperature exceeds approximately 150C, while current limiting restricts output current to approximately 1.1A under overload conditions.

• 5V to 3.3V regulation in digital and MCU systems
• Post-regulation after DC-DC switching converters
• Battery-powered instrumentation and meters
• PC add-on card and motherboard clock supply
• LCD monitor and set-top box power rails