AD5165BUJZ100-R7 is a single-channel, 128-position, volatile digital potentiometer (digipot) designed and manufactured by Analog Devices Inc. (ADI). It belongs to the ultra-compact AD516x family, engineered for space-constrained, low-power, and cost-sensitive applications, where replacing mechanical potentiometers with reliable, programmable, and solderable ICs improves long-term stability, eliminates wear-out, and enables remote calibration and dynamic gain/offset adjustment.
The “BUJZ” suffix denotes the 8-lead SOT-23 package (2.9 mm × 1.6 mm) — one of the smallest standard surface-mount packages available; the “100” indicates a 100 kΩ end-to-end resistance (RAB); and the “-R7” signifies 7-inch tape-and-reel packaging (1,000 units per reel), Pb-free, RoHS-compliant, and qualified for industrial operation (–40°C to +105°C junction temperature).
⚠️ Critical Clarification:
The AD5165 is volatile: its wiper position is not retained after power-down — it resets to mid-scale (64) on power-up. This is intentional and advantageous for safety-critical or fail-safe systems (e.g., bias circuits, sensor conditioning), where a known default state is required at startup. For non-volatile (EEPROM-based) storage of wiper position, ADI offers the pin-compatible AD5162 (dual-channel) or AD5170 (single-channel, non-volatile), but the AD5165 prioritizes speed, lower cost, higher reliability (>1 million write cycles vs. EEPROM’s ～100k), and smaller size.
It operates from a single 2.7 V to 5.5 V supply, consumes only < 5 µA quiescent current, and communicates via a simple 3-wire SPI-compatible serial interface (up to 10 MHz), requiring no external components.
Introduction
The AD5165BUJZ100-R7 delivers precision analog control in a microscopic footprint:
🔹 128-step resolution (7-bit) — enabling fine-grained adjustment (e.g., ±0.8% steps across 100 kΩ);
🔹 Low wiper resistance: 60 Ω (typ.), < 100 Ω (max) — minimizes signal degradation and THD in audio and sensor paths;
🔹 Low temperature coefficient: 35 ppm/°C (typ.) — far superior to mechanical pots (500–1000 ppm/°C), ensuring stable gain over temperature;
🔹 Rail-to-rail operation: supports analog signals from 0 V to VDD, with no level-shifting needed;
🔹 Robust analog performance: bandwidth > 1 MHz (at RAB = 100 kΩ), THD < −90 dB (at 1 kHz), and excellent linearity (±0.3% RINL).
Its SOT-23-8 (BUJZ) package (2.9 mm × 1.6 mm) features an exposed pad for thermal enhancement — enabling full 100 kΩ operation even in high-temperature environments when properly laid out. With only three external connections required (VDD, GND, and SPI lines), it replaces bulky, unreliable mechanical trimmers while offering programmability, repeatability, and immunity to vibration, dust, and oxidation.
Key Features
✅ Precision Digital Potentiometer Core:
• Resolution: 128 positions (7-bit);
• End-to-end resistance (RAB): 100 kΩ (±20% tolerance);
• Wiper resistance (RW): 60 Ω (typ.), < 100 Ω (max);
• Integral nonlinearity (INL): ±0.3% RAB, Differential nonlinearity (DNL): ±0.2 LSB.
✅ Ultra-Low Power & Compact Size:
• Supply voltage: 2.7 V to 5.5 V;
• Quiescent current: < 5 µA (typ.), < 10 µA (max);
• Package: 8-lead SOT-23 (2.9 mm × 1.6 mm) with exposed pad (BUJZ) — smallest digipot in its class;
• Operating temperature: –40°C to +105°C.
✅ High Performance & Robustness:
• Temperature coefficient: 35 ppm/°C (typ.), < 100 ppm/°C (max);
• Bandwidth: > 1 MHz (RAB = 100 kΩ);
• Total harmonic distortion (THD): < –90 dB @ 1 kHz;
• Overvoltage protection: ±5 V on A/B/W pins (beyond supply rails).
✅ Simple 3-Wire Serial Interface:
• SPI-compatible (mode 0,0 and 1,1 supported);
• Clock rate: up to 10 MHz — enables fast reconfiguration (< 1 µs per write);
• No external components required — internal pull-downs on /CS and DIN ensure defined state at power-up.
✅ Volatile Operation & Fail-Safe Default:
• Wiper resets to mid-scale (64) on power-up — ensures predictable, safe startup behavior;
• No EEPROM wear-out — unlimited write cycles (>10 million), ideal for dynamic real-time adjustment.
Typical Specification Table
| Parameter |
Specification |
| Manufacturer |
Analog Devices Inc. (ADI) |
| Product Series |
AD516x Family (Ultra-Compact Digital Potentiometers) |
| Model |
AD5165BUJZ100-R7 |
| Function |
Single-Channel, Volatile Digital Potentiometer |
| Resolution |
128 positions (7-bit) |
| End-to-End Resistance (RAB) |
100 kΩ (±20%) |
| Wiper Resistance (RW) |
60 Ω (typ.), < 100 Ω (max) |
| INL / DNL |
±0.3% RAB / ±0.2 LSB |
| Tempco (RAB) |
35 ppm/°C (typ.), < 100 ppm/°C (max) |
| Bandwidth |
> 1 MHz (RAB = 100 kΩ) |
| THD |
< –90 dB @ 1 kHz |
| Supply Voltage |
2.7 V to 5.5 V |
| Quiescent Current |
< 5 µA (typ.), < 10 µA (max) |
| Interface |
3-Wire SPI (up to 10 MHz), /CS, SCLK, DIN |
| Power-Up Default |
Wiper = Mid-scale (64) |
| Package |
8-Lead SOT-23 (2.9 mm × 1.6 mm) with Exposed Pad (BUJZ) |
| RoHS / Green |
Yes (Pb-free, Halogen-free) |
| Packaging |
7-inch Reel, 1,000 units (R7) |
Typical Applications
🔹 Precision Sensor Signal Conditioning: Gain/offset trimming in bridge amplifiers (load cells), RTD/thermistor interfaces, and pressure transmitters — leveraging low tempco and high repeatability to eliminate manual calibration.
🔹 Programmable Gain Amplifiers (PGAs): Configurable gain stages in data acquisition systems, medical instrumentation (ECG, EEG), and test equipment — enabling automatic range selection and auto-zeroing.
🔹 Audio Equipment: Volume control, tone adjustment, and balance control in portable speakers, hearing aids, and professional audio mixers — benefiting from low THD and rail-to-rail operation.
🔹 Industrial Process Control: Calibration of 4–20 mA transmitter outputs, loop-powered sensor biasing, and PID controller tuning — using digital control for remote recalibration without opening enclosures.
🔹 Battery-Powered & Portable Devices: Smart thermostats, handheld meters, and IoT edge nodes — enabled by < 5 µA quiescent current and SOT-23 size.
🔹 Automotive Cabin Electronics: Seat/mirror position memory, ambient light/humidity sensor calibration, and infotainment audio controls — meeting AEC-Q200 stress requirements (qualified per ADI’s automotive reliability program).
Development & Design Notes
🔧 PCB Layout Best Practices:
- Use a solid ground plane beneath the SOT-23 — connect the exposed pad (EP) to it with ≥ 4 thermal vias (0.25 mm) to improve thermal stability and reduce noise coupling.
- Keep analog traces (A, B, W) short and away from noisy digital lines (e.g., SCLK, /CS) — use ground guard rings if routing density is high.
- Avoid placing the digipot near heat sources (e.g., power inductors) — its 35 ppm/°C tempco means 10°C rise = 350 ppm error (～0.035% of 100 kΩ).
🔧 Power Supply Decoupling:
- Place a 100 nF X7R ceramic capacitor within 1 mm of VDD and GND pins — critical for clean SPI communication and low-noise analog performance.
- For best THD in audio applications, add a 10 µF tantalum capacitor near the power entry point — improves low-frequency PSRR.
🔧 SPI Interface & Firmware Integration:
- Use 2.2 kΩ pull-down resistors on /CS and DIN — ensures defined state during reset/boot.
- Leverage ADI’s EVAL-AD5165SDZ evaluation board and ACE software for rapid prototyping and register validation.
- Implement write-verify in firmware: after writing a new wiper code, read back the RDAC register to confirm successful update — prevents silent configuration failures.
🔧 Thermal Management & Reliability:
- The SOT-23 has no large thermal pad — θJA ≈ 250°C/W. For continuous operation above +50°C ambient, ensure ≥ 25 mm² copper pour under the IC and use forced airflow.
- FIT rate = 32 failures per billion hours, with FMEDA report supporting IEC 61508 SIL-2 — combine periodic self-test (e.g., measure VW vs. expected code) for functional safety compliance.
🔧 Calibration & Accuracy Optimization:
- Perform one-time factory calibration (gain/offset) at room temperature — the device retains calibration over temperature due to matched on-chip components.
- For metrology-grade applications, use external 0.1% metal-film resistors as RA/RB terminations — avoids tolerance impact from ±20% RAB.
