1A LOW DROPOUT LINEAR REGULATOR # AZ1117T18E1 Low Dropout Voltage Regulator Technical Documentation
Manufacturer : BCD Semiconductor Manufacturing Limited
## 1. Application Scenarios
### Typical Use Cases
The AZ1117T18E1 is a 1.8V fixed-output low dropout (LDO) voltage regulator designed for applications requiring stable, clean power supply with minimal voltage headroom. Typical use cases include:
- Battery-Powered Systems : Portable devices, IoT sensors, and handheld instruments where battery voltage decreases over time but stable 1.8V rail is required
- Post-Regulation : Secondary regulation following switching regulators to reduce noise and ripple
- Microprocessor/Microcontroller Power : Providing clean 1.8V core voltage for modern MCUs, DSPs, and FPGAs
- Analog Circuit Power : Sensitive analog circuits requiring low-noise power supplies
- Memory Module Power : DDR memory and other memory interfaces requiring precise 1.8V supply
### Industry Applications
- Consumer Electronics : Smartphones, tablets, digital cameras, portable media players
- Industrial Automation : PLCs, sensor interfaces, control systems
- Telecommunications : Network equipment, base stations, communication modules
- Medical Devices : Portable medical monitors, diagnostic equipment
- Automotive Electronics : Infotainment systems, body control modules (within specified temperature ranges)
### Practical Advantages and Limitations
Advantages:
- Low Dropout Voltage : Typically 1.1V at 1A load, enabling operation with small input-output differential
- High Accuracy : ±1% output voltage tolerance over line, load, and temperature variations
- Current Limiting & Thermal Protection : Built-in protection against overload and overtemperature conditions
- Low Quiescent Current : Typically 5mA, suitable for battery-operated applications
- Compact Package : SOT-223 package offers good thermal performance in small footprint
Limitations:
- Fixed Output : 1.8V fixed output limits flexibility for different voltage requirements
- Power Dissipation : Maximum 1A output current requires proper heat sinking for continuous operation
- Input Voltage Range : Maximum 15V input voltage may not suit all high-voltage applications
- Dropout Voltage : While low, may still be too high for very low-voltage battery applications
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Insufficient Heat Management
- Problem : Operating at high current loads without adequate cooling causes thermal shutdown
- Solution : Implement proper PCB copper pour for heat dissipation, consider adding heatsink for continuous high-current operation
Pitfall 2: Input Capacitor Selection
- Problem : Using capacitors with insufficient ESR or incorrect values causing instability
- Solution : Use 10μF tantalum or low-ESR electrolytic capacitor at input, placed close to regulator
Pitfall 3: Output Capacitor Issues
- Problem : Insufficient output capacitance or incorrect ESR leading to oscillation
- Solution : Minimum 22μF tantalum or low-ESR electrolytic capacitor at output; ceramic capacitors may require series resistance
Pitfall 4: Layout Problems
- Problem : Long traces between regulator and capacitors causing instability and poor regulation
- Solution : Place input and output capacitors as close as possible to regulator pins
### Compatibility Issues with Other Components
Input Source Compatibility:
- Compatible with lithium-ion batteries (3.7V nominal), 5V systems, and higher voltage supplies up to 15V
- May require pre-regulation for inputs exceeding 15V absolute maximum
Load Compatibility:
- Ideal for digital ICs, memory devices, and analog circuits requiring 1.8V supply
- Not suitable for loads requiring rapid transient response beyond regulator capabilities
