Professional IC Distribution & Technical Solutions

The REF25D is a precision voltage reference manufactured by Plessey Semiconductors.

Specifications:

• Output Voltage: 2.5V ±0.1% (typical)
• Initial Accuracy: ±0.1% (max)
• Temperature Coefficient: 5 ppm/°C (typical)
• Operating Temperature Range: -40°C to +85°C
• Long-Term Stability: 20 ppm/1000 hours (typical)
• Supply Voltage Range: 4V to 40V
• Output Current Capability: 10 mA (max)
• Package: TO-39 metal can

Descriptions:

The REF25D is a high-precision, low-drift voltage reference designed for applications requiring stable and accurate voltage references. It features excellent temperature stability and low noise, making it suitable for precision analog circuits, data converters, and instrumentation.

Features:

• High precision (±0.1% initial accuracy)
• Low temperature coefficient (5 ppm/°C typical)
• Wide operating voltage range (4V to 40V)
• Low output noise
• Robust TO-39 metal can package
• Long-term stability (20 ppm/1000 hours)

This component is ideal for use in precision measurement systems, industrial controls, and high-accuracy analog circuits.

# REF25D Voltage Reference: Application, Design Considerations, and Implementation

## Practical Application Scenarios

The REF25D from PLESSEY is a precision voltage reference IC designed for applications requiring stable, low-noise voltage regulation. Its key specifications—low temperature drift (typically 5ppm/°C) and high initial accuracy (±0.05%)—make it suitable for demanding environments.

High-Precision Data Acquisition Systems

In 16-bit+ ADCs or DACs, the REF25D ensures minimal voltage drift, reducing conversion errors. Its low output noise (3µVpp typical) is critical for medical instrumentation and seismic sensors, where signal integrity is paramount.

Industrial Control Systems

The REF25D’s wide operating temperature range (-40°C to +125°C) suits harsh industrial environments, such as motor control units or PLCs. Its ability to maintain stability under load variations (sourcing up to 10mA) prevents calibration drift in long-term deployments.

Battery-Powered Devices

With a low quiescent current (150µA), the REF25D is ideal for portable equipment like handheld meters or IoT sensors. Its shutdown mode further reduces power consumption during idle periods.

## Common Design Pitfalls and Avoidance Strategies

Thermal Management Errors

Pitfall: Ignoring thermal gradients can degrade performance, especially in high-precision applications.

Solution: Place the REF25D away from heat sources (e.g., power regulators) and use thermal vias or ground planes to dissipate heat.

Improper Decoupling

Pitfall: Insufficient decoupling leads to noise coupling or instability.

Solution: Use a 1µF ceramic capacitor (X7R) at the output and a 0.1µF capacitor at the input, placed as close as possible to the IC pins.

Load Regulation Oversights

Pitfall: Exceeding the 10mA output current limit causes voltage droop.

Solution: For higher current demands, buffer the output with a low-noise op-amp in a voltage-follower configuration.

## Key Technical Considerations for Implementation

PCB Layout

• Minimize trace lengths to the REF25D’s output to reduce noise pickup.
• Use a star-ground configuration to avoid ground loops.

Startup Behavior

The REF25D exhibits a soft-start characteristic (~200µs settling time). Designers should account for this delay in systems requiring rapid power cycling.

Environmental Factors

For applications exposed to humidity or contaminants, conformal coating may be necessary to protect the REF25D’s performance, as moisture ingress can alter output stability.

By addressing these factors, engineers can fully leverage the REF25D’s precision capabilities while mitigating common integration challenges.