AMS1117-ADJS

Overview

The EVVO AMS1117-ADJS is a positive adjustable low dropout linear regulator (LDO) capable of delivering up to 1A output current. It features an internal bandgap reference voltage with a typical value of 1.25V and an accuracy of less than 1.5%. The device operates within an input voltage range of up to 18V absolute maximum, with recommended operating conditions up to 12V. Dropout voltage is typically 1.2V at 1A load. It includes thermal shutdown and current limiting protection. Available in SOT-223-3L, TO-252-2L, and SOT-89-3L packages, it supports an operating junction temperature range of -40°C to +125°C.

Feature Summary

• Adjustable output voltage via external resistors
• Integrated thermal shutdown and current limiting protection
• Low dropout voltage operation for high efficiency
• High ripple rejection ratio for clean power supply

Applications

• Battery chargers
• Post-regulators for switching mode power supplies
• Portable instrumentation
• Cellular and cordless telephones
• Notebook and palmtop computers

Procurement Notes

Verify the specific package variant (SOT-223-3L, TO-252-2L, or SOT-89-3L) required for your design, as pinouts and thermal characteristics differ. Confirm that the manufacturer datasheet aligns with your PCB footprint and thermal management requirements. Ensure input and output capacitor values meet stability criteria specified in the application circuit section.

Selection Notes

Select this component when an adjustable voltage rail between approximately 1.25V and the input voltage minus dropout is needed. It is suitable for applications requiring up to 1A continuous current with moderate line and load regulation needs. Consider thermal resistance and ambient temperature constraints when designing for high power dissipation scenarios.

Part Context

The AMS1117 series is a widely used family of three-terminal LDO regulators. The ADJ suffix denotes the adjustable version, allowing designers to set the output voltage using two external resistors. This model provides flexibility compared to fixed-voltage variants while maintaining the core benefits of low dropout and robust protection features common to the series.

Replacement Considerations

Pin-compatible alternatives include other 1A LDO regulators in similar packages. Verify that replacement parts match the reference voltage tolerance, dropout characteristics, and thermal performance specifications.

FAQ

How is the output voltage determined for the AMS1117-ADJS?

The output voltage is set by two external resistors connected to the ADJ pin, following the formula VOUT = VREF × (1 + R2/R1) + IADJ × R2, where VREF is typically 1.25V.

What protection features are included in the AMS1117-ADJS?

The device includes thermal shutdown to protect against excessive junction temperatures and current limiting to prevent damage during overload or short-circuit conditions.

What is the minimum dropout voltage for this regulator?

The typical dropout voltage is 1.2V at a 1A load current, though it decreases at lower load currents.