Power management
Voltage Reference
Stable, low-noise voltage source for ADCs, DACs, and precision analog circuits.
What is it?
A voltage reference is a precision IC that outputs a stable voltage (e.g., 1.25 V, 2.5 V, 4.096 V) across temperature, time, and load variation. Used wherever measurement accuracy matters — ADC reference input, DAC output scaling, comparator threshold setting. Better than using the supply rail (which moves with battery / regulator), better than a Zener (drifts with temperature).
When do you need it?
- ADC reference input (the accuracy of your measurement is bounded by the reference accuracy).
- DAC full-scale reference.
- Precision current source / sink circuits.
- Power-supply over-voltage / under-voltage threshold setting.
- Sensor excitation voltage where ratiometric measurement isn't possible.
How to pick the right one
- Output voltage
- Common: 1.25 V, 2.048 V, 2.5 V, 3.0 V, 4.096 V, 5.0 V. Match to your ADC/DAC reference input.
- Initial accuracy
- ±0.1% (laser-trimmed precision) to ±2% (general purpose). For 16-bit ADCs, accuracy >±0.1% is wasted because resolution is finer.
- Temperature drift (ppm/°C)
- 5-25 ppm/°C for general use, <5 ppm/°C for instrumentation.
- Long-term drift
- Typically specified in ppm/√khr. Matters for instruments that must hold calibration for years.
- Noise (μV peak-to-peak in 0.1-10 Hz band)
- Critical for low-noise analog. Bandgap references are quieter than series Zener types.
- Output current and topology
- Series (3-terminal) for driving loads. Shunt (2-terminal Zener-like) for low-current threshold applications, simpler.
What Magnias offers
Magnias voltage reference portfolio includes shunt-type adjustable references (TL431-class) and fixed-voltage series references in SOT-23 packages. Suitable for general-purpose ADC reference and threshold-setting applications.
Common questions
TL431 — is it really a voltage reference?
Yes, the most common one ever — it's a programmable shunt reference with internal bandgap, used as a regulator feedback element and a general-purpose 2.5 V reference.
Series or shunt reference?
Series (3-terminal) gives you a regulated output node that can drive other circuits — like a tiny LDO. Shunt (2-terminal) just sits across a current source like a Zener and clamps the voltage — lower current, simpler, but no drive capability.
Bandgap vs Zener-based reference?
Bandgap: lower noise, lower voltage (typically <2 V), works at low supply. Zener (buried): higher noise but better long-term stability, typically 6.3 V+.