2.5V Micropower, Low Noise Precision Voltage References with Shutdown# ADR391AUJZREEL7 Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The ADR391AUJZREEL7 is a precision voltage reference IC primarily employed in applications requiring stable, accurate voltage sources. Key use cases include:
- High-Precision Data Acquisition Systems : Serving as reference voltage for 16-bit to 24-bit ADCs in measurement equipment
- Industrial Process Control : Providing stable references for sensor signal conditioning circuits
- Medical Instrumentation : Used in patient monitoring equipment where voltage accuracy is critical
- Portable Test Equipment : Battery-powered devices requiring low power consumption with high accuracy
- Automotive Electronics : Engine control units and sensor interfaces requiring temperature-stable references
### Industry Applications
- Industrial Automation : PLCs, motor controllers, and process instrumentation
- Communications Infrastructure : Base station power management and signal processing
- Consumer Electronics : High-end audio equipment and precision power supplies
- Aerospace and Defense : Avionics systems and military-grade test equipment
- Energy Management : Smart grid monitoring and power quality analysis systems
### Practical Advantages and Limitations
Advantages:
- Low Temperature Coefficient : 3 ppm/°C maximum ensures stability across operating temperatures
- Low Noise Performance : 3.8 μVp-p (0.1 Hz to 10 Hz) minimizes signal interference
- Low Power Consumption : 100 μA maximum supply current extends battery life
- High Initial Accuracy : ±0.06% maximum error reduces calibration requirements
- Small Package : SOT-23-6 enables space-constrained designs
Limitations:
- Limited Output Current : 10 mA maximum requires buffer for high-current applications
- Temperature Range : -40°C to +125°C may not suit extreme environment applications
- Cost Considerations : Higher precision comes at premium compared to basic references
- Load Regulation : 60 ppm/mA may require additional regulation for dynamic loads
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Decoupling
- Issue : Poor transient response and increased noise
- Solution : Use 1 μF ceramic capacitor at input and 1 μF at output, placed within 5 mm
Pitfall 2: Thermal Management
- Issue : Self-heating affects accuracy in high-ambient temperatures
- Solution : Implement thermal vias under package and ensure adequate airflow
Pitfall 3: PCB Contamination
- Issue : Leakage currents degrading precision performance
- Solution : Use conformal coating and guard rings around sensitive nodes
Pitfall 4: Layout-Induced Noise
- Issue : Digital noise coupling into reference circuitry
- Solution : Separate analog and digital grounds, use star grounding technique
### Compatibility Issues with Other Components
ADC/DAC Interfaces:
- Ensure reference voltage matches ADC full-scale input range
- Verify settling time compatibility with conversion rates
- Check for reference input impedance requirements
Amplifier Circuits:
- Buffer amplifiers may be needed for high-load applications
- Consider amplifier offset and drift when cascading stages
- Match impedance levels to prevent loading effects
Power Supply Requirements:
- Operates from 4.5V to 18V supply range
- Ensure power supply noise < reference noise specification
- Consider LDO regulation for noisy supply environments
### PCB Layout Recommendations
Power Distribution:
- Use separate power planes for analog and digital sections
- Implement star-point grounding at reference IC
- Route power traces with minimum 20 mil width
Component Placement:
- Place decoupling capacitors immediately adjacent to IC pins
- Position reference IC away from heat-generating components
- Keep sensitive analog traces short and direct
Routing Guidelines
