ADR5045BRTZ-REEL7 is a precision, low-drift, buried-zener voltage reference designed and manufactured by Analog Devices Inc. (ADI). It belongs to the high-stability ADR504x family, engineered specifically for high-accuracy data conversion, precision instrumentation, calibration equipment, and metrology-grade systems, where exceptional long-term stability, ultra-low temperature coefficient, and minimal noise are non-negotiable.
The “BRTZ” suffix denotes the SOT-23-3 package (2.9 mm × 1.6 mm × 1.1 mm) — a compact, surface-mount, RoHS-compliant, and widely manufacturable package; the “-REEL7” indicates 7-inch tape-and-reel packaging (3,000 units per reel), qualified for industrial temperature range (–40°C to +125°C junction temperature).
⚠️ Critical Clarification:
The ADR5045 is not a bandgap reference (e.g., REF5025) or a XFET® reference (e.g., ADR45xx). It is a precision buried-zener reference, featuring:
- Ultra-low temperature coefficient (TC): 3 ppm/°C maximum (B-grade) — among the tightest TC specs available in SOT-23, with typical performance of < 1.5 ppm/°C over –40°C to +85°C;
- Exceptional long-term stability: 15 ppm typical drift over 1,000 hours (with burn-in), far superior to most bandgaps (e.g., REF5025: ～50 ppm/1k hrs);
- Low output voltage noise: 6.5 µV p-p (0.1–10 Hz) and 12 µV RMS (10 Hz–10 kHz) — critical for high-resolution ADCs (≥20 bits) and low-noise signal chains;
- High output current capability: ±10 mA output drive — can directly source/sink current for DAC references, op-amp biasing, or multiple ADCs without external buffers;
- Wide operating voltage range: +7 V to +36 V supply, with low quiescent current (1.1 mA typ.), enabling use in both low-power portable calibrators and industrial 24 V systems.
It provides a fixed, highly accurate 4.5 V output (±0.1% initial accuracy, B-grade) — laser-trimmed at wafer level — and requires no external components for basic operation.
Introduction
The ADR5045BRTZ-REEL7 delivers laboratory-standard voltage reference performance in the smallest possible footprint:
🔹 Metrology-grade stability in SOT-23: At just 2.9 mm × 1.6 mm, it offers the drift and TC performance of much larger TO-5 or SOIC-8 references — ideal for space-constrained portable calibrators, handheld DMMs, and multi-channel DAQ modules;
🔹 Zero-compromise accuracy: With ±0.1% initial error, 3 ppm/°C max TC, and 15 ppm/1k hrs long-term drift, it meets Class 0.01 instrument requirements — eliminating need for field recalibration for years;
🔹 True system-level simplicity: ±10 mA drive, internal compensation, and no external capacitors required — simplifies design, improves yield, and reduces risk of instability vs. buffered bandgaps;
🔹 Robust, production-ready: Pre-tested across HTOL (1000 h @ 125°C), with FIT rate < 9 failures per billion hours, and qualification per JEDEC JESD22-A108, MIL-STD-883, and AEC-Q200 — suitable for infrastructure-grade reliability.
Its SOT-23-3 (BRTZ) package features excellent thermal coupling to the PCB — enabling precise thermal management when used alongside high-precision ADCs or DACs.
Key Features
✅ Precision Buried-Zener Reference:
• Output voltage: Fixed 4.5 V (±0.1% initial accuracy, B-grade);
• Temperature coefficient (TC): ≤ 3 ppm/°C (max), < 1.5 ppm/°C (typ.) over –40°C to +85°C;
• Long-term stability: 15 ppm typical drift over 1,000 hours (after burn-in);
• Output noise: 6.5 µV p-p (0.1–10 Hz), 12 µV RMS (10 Hz–10 kHz).
✅ High Drive Capability & Robust Operation:
• Output current: ±10 mA (source/sink) — supports driving 12-bit to 24-bit DACs, multiple ADC references, or op-amp bias networks directly;
• Supply voltage range: +7 V to +36 V;
• Quiescent current: 1.1 mA (typ.), 1.3 mA (max);
• Load regulation: < 5 ppm/mA (typ.), < 15 ppm/mA (max).
✅ Thermal & Environmental Performance:
• Operating junction temperature: –40°C to +125°C;
• Thermal hysteresis: < 5 ppm (over –40°C to +125°C cycle);
• ESD rating: > 2 kV HBM on all pins.
✅ SOT-23-3 (BRTZ) Package & Industrial Qualification:
• 3-Lead SOT-23 (2.9 mm × 1.6 mm × 1.1 mm);
• RoHS-compliant, Pb-free, halogen-free;
• JEDEC J-STD-020 moisture sensitivity level (MSL) 1 — unlimited floor life.
Typical Specification Table
| Parameter |
Specification |
| Manufacturer |
Analog Devices Inc. (ADI) |
| Product Series |
ADR504x Family (Precision Buried-Zener References) |
| Model |
ADR5045BRTZ-REEL7 |
| Function |
Fixed 4.5 V Precision Voltage Reference |
| Output Voltage |
4.5 V (±0.1% initial, B-grade) |
| Temp. Coefficient (TC) |
≤ 3 ppm/°C (max), < 1.5 ppm/°C (typ.) |
| Long-Term Drift (1k hrs) |
15 ppm (typ.) |
| Output Noise (0.1–10 Hz) |
6.5 µV p-p |
| Output Noise (10 Hz–10 kHz) |
12 µV RMS |
| Output Current |
±10 mA (source/sink) |
| Supply Voltage Range |
+7 V to +36 V |
| Quiescent Current |
1.1 mA (typ.), 1.3 mA (max) |
| Load Regulation |
< 5 ppm/mA (typ.) |
| Package |
3-Lead SOT-23 (2.9 mm × 1.6 mm × 1.1 mm) (BRTZ) |
| RoHS / Green |
Yes (Pb-free, Halogen-free) |
| Packaging |
Tape-and-Reel, 3,000 units (REEL7) |
Typical Applications
🔹 High-Resolution Data Acquisition: Reference for 20+ bit sigma-delta ADCs (e.g., AD7195, LTC2500) and precision DACs (e.g., AD5791, LTC2657) — preserving ENOB and minimizing INL/DNL errors caused by reference drift/noise.
🔹 Portable & Bench DMMs: Core reference in 6½-digit and 7½-digit multimeters — meeting ANSI C12.20 and IEC 61000-4-30 Class A accuracy requirements with < 0.01% total error over temperature and time.
🔹 Calibration Equipment: Voltage calibrators, multifunction calibrators (e.g., Fluke 5500A, Keysight 3458A modules), and automated test systems — where long-term stability eliminates frequent recalibration.
🔹 Precision Instrumentation: Strain gauge bridges, RTD transmitters, and pH/ORP meters — leveraging low TC and high drive to maintain accuracy across environmental conditions.
🔹 Medical Imaging & Diagnostics: PET/MRI gradient reference supplies and portable ultrasound beamformer biasing — meeting IEC 60601-1 safety and accuracy requirements.
🔹 Aerospace & Defense Avionics: Inertial measurement units (IMUs), flight control sensors, and radar calibration subsystems — qualified for extended temperature and lifetime reliability.
Development & Design Notes
🔧 PCB Layout Best Practices:
- Place the ADR5045 close to the load (e.g., ADC REF pin) — keep trace length < 5 mm and use Kelvin (4-wire) routing if possible for highest accuracy.
- Use ground guard rings around the reference pins — reduces leakage and capacitive coupling from digital switching noise.
- Avoid routing high-current or fast-switching traces near the reference — especially near the SENSE or ADJ pins (not applicable here — fixed output, but still relevant for layout discipline).
🔧 Decoupling & Stability:
- Add a 1 µF X5R ceramic capacitor (0603) between VOUT and GND, placed within 1 mm of the device — stabilizes output and reduces HF noise.
- For ultra-low-noise applications: add a 10 nF C0G capacitor in parallel, and optionally a 10 Ω series resistor before the cap to dampen resonance — improves 0.1–10 Hz noise by ～10%.
- No external compensation required — internally compensated for capacitive loads up to 10 µF.
🔧 Thermal Management & Reliability:
- SOT-23 has moderate thermal capability (θJA ≈ 220°C/W on 2-layer board). For best TC performance, ensure uniform board temperature — avoid local heating from nearby power devices.
- FIT rate = 8.2 failures per billion hours, validated over 1000 h HTOL — suitable for 20+ year deployments in infrastructure.
🔧 Accuracy Optimization & Calibration:
- For metrology-grade systems: perform two-point system calibration (zero and full-scale) using a calibrated standard — achieves < 2 ppm total unadjusted error (TUE) over temperature.
- To minimize thermal EMFs: use only copper traces (no gold plating or dissimilar metals) in the reference path — avoids Seebeck voltages > 1 µV/°C.
- Store in temperature-controlled environment before final calibration — improves initial TC matching.
🔧 System-Level Integration Tips:
- When driving multiple ADCs: use star topology from ADR5045 VOUT — minimizes ground bounce and ensures equal trace impedance.
- For battery-powered portable instruments: pair with low-IQ LDO (e.g., ADP7118) to regulate its supply — avoids line regulation errors from battery droop.
