AMS1117-1.8

Overview

The AMS1117-1.8 is a positive low dropout linear regulator providing a fixed 1.8V output with a maximum current of 1A. It features an input voltage range up to 18V and operates within a junction temperature range of -40°C to +125°C. The device guarantees a typical dropout voltage of 1.2V at full load, with line regulation of 9mV and load regulation of 10mV. Quiescent current is typically 5mA, while ripple rejection reaches 60dB at 120Hz. Thermal shutdown activates at 150°C, and current limiting caps at 2.5A.

Feature Summary

• Fixed 1.8V output with less than 1.5% tolerance
• Integrated thermal shutdown for overload protection
• On-chip current limiting prevents excessive stress
• Low dropout operation optimized for transient response

Applications

• Laptop, Palmtop, and Notebook Computers
• Battery Charger Systems
• SCSI-II Active Terminator
• Cellular Phone Power Management
• SMPS Post-Regulator

Procurement Notes

Verify the specific package variant (SOT-223-3L, SOT-89-3L, or TO-252-2L) required for your PCB layout before ordering. Confirm that the supplier provides the official datasheet matching the AMS1117-1.8 specification sheet. Ensure the component meets the operating junction temperature range of -40°C to +125°C for your intended environment. Check lead soldering temperature ratings against your assembly process requirements.

Selection Notes

Select this regulator when a stable 1.8V rail is needed for digital logic or sensors drawing up to 1A. The low dropout characteristic allows efficient power conversion from slightly higher voltages like 3.3V or 5V. Consider the thermal resistance of the chosen package to manage heat dissipation under high load conditions. Ensure adequate input-to-output voltage differential to maintain regulation without triggering thermal shutdown.

Part Context

The AMS1117 series includes adjustable and fixed voltage variants such as 1.2V, 1.5V, 2.5V, 3.3V, and 5.0V. These regulators are designed for low-voltage applications requiring high efficiency and minimal heat generation. The series utilizes a PNP-driven NPN pass transistor architecture to achieve its low dropout performance across various surface mount packages.

Replacement Considerations

Compatible substitutes include other 1A LDOs with 1.8V fixed output and similar pinouts, such as the LD1117S18 or AP1117-1.8. Verify that replacement parts match the 1.8V output tolerance and thermal shutdown thresholds. Ensure the alternative component supports the same SOT-223-3L or SOT-89-3L footprint for direct board integration.