AD5291BRUZ-20 - 20kΩ 256-Position SPI Digital Potentiometer | ADI
MPN: AD5291BRUZ-20 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.2 | $4.20 |
| 10 | $3.78 | $37.80 |
| 100 | $3.36 | $336.00 |
| 500 | $3.02 | $1,510.00 |
| 1,000 | $2.69 | $2,690.00 |
AD5291BRUZ-20 Overview
A digital potentiometer (often abbreviated digi-pot or RDAC) is a digitally controlled variable resistor that emulates a mechanical potentiometer through a tapped resistor ladder switched by MOSFET transistors. It belongs to the broader category of digital-to-analog converters (DAC) used for resistance, which in turn sits within data-acquisition and signal-conditioning components. Compared to mechanical trimmers, a digi-pot offers remote adjustment, no mechanical wear, and software-controlled calibration.
Key features of the AD5291BRUZ-20 include ±1% end-to-end resistance tolerance, a low 5 ppm/°C nominal temperature coefficient, 256 uniform tap points with 5 V/5.5 V single-supply operation, and a 20-time-programmable nonvolatile memory for storing the wiper position through power-down. The part also integrates a hardware RESET pin and software reset command that reloads the most recently programmed 20-TP memory location, plus a power-on refresh circuit that reinitializes the wiper on supply ramp.
The internal architecture is a precision thin-film resistor ladder with CMOS transmission-gate switches, driven by an internal RDAC register. A separate 20-bit (AD5291) or 50-bit (AD5292) EEPROM cell stores the user-programmed wiper position. The SPI interface supports daisy-chaining of multiple devices via a dedicated SDO pin, and the logic supply range of 1.7 V to 5.5 V permits direct connection to 1.8 V, 3.3 V, or 5 V microcontrollers without level shifters.
Typical applications include programmable gain amplifiers and transimpedance amplifiers, precision reference voltage trimming in instrumentation, audio volume and tone control, LCD display contrast adjustment, programmable filter cutoff and oscillator tuning, and industrial 4–20 mA loop calibration. The TSSOP-14 footprint is friendly to handheld and portable designs where board area is constrained.
When designing with this device, observe the absolute maximum analog supply voltage of 6.5 V and keep the logic supply within 1.7 V to 5.5 V. Bypass VDD and VL with 0.1 µF capacitors placed within 5 mm of the supply pins, and reserve a small footprint for an optional 1 µF bulk cap on VDD if the supply is noisy.
This page synthesizes distributor pricing, drop-in alternatives sourced from the AD5291 family and competitor cross-reference, and practical design notes not found in the manufacturer datasheet alone, helping engineers select and qualify the AD5291BRUZ-20 faster.
Drop-in alternatives for AD5291BRUZ-20 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with AD5291BRUZ-20 (same form factor and footprint) — differing in End-to-End Resistance (R-AB), Nonvolatile Memory, Number of Taps, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AD5291BRUZ-50
✅ Drop-In📋 Reference alternative (not in catalog)
AD5291BRUZ-100
✅ Drop-In📋 Reference alternative (not in catalog)
AD5292BRUZ-20
✅ Drop-In📋 Reference alternative (not in catalog)
AD5291BRUZ-20-RL7
✅ Drop-In📋 Reference alternative (not in catalog)
AD5270BCPZ-20
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$4.65 / Unit
View Datasheet →AD5291BRUZ-20 Maximum Ratings & Electrical Characteristics
| Number of Channels | 1 |
| Number of Taps | 256 |
| End-to-End Resistance (R-AB) | 20 kΩ |
| Resistance Tolerance | ±1% (max) |
| Temperature Coefficient (Rheostat Mode) | 5 ppm/°C (typ) |
| Digital Interface | SPI (Mode 1, Mode 3) |
| Analog Supply Voltage (VDD) | 2.7 V to 5.5 V |
| Logic Supply Voltage (VL) | 1.7 V to 5.5 V |
| Wiper Resistance | 50 Ω (typ) |
| Nonvolatile Memory | 20-time programmable (20-TP) |
| Operating Temperature Range | -40 °C to +105 °C |
| Package | 14-pin TSSOP (RU-14) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited) |
| Lead-Free / RoHS | Yes / Compliant |
| Reset Input | Hardware RESET pin + software reset (Command 4) |
AD5291BRUZ-20 Pin Configuration
| Pin 1 | VDD — Analog supply voltage, 2.7 V to 5.5 V |
| Pin 2 | GND — Ground reference for analog supply |
| Pin 3 | RES — Hardware reset input (active low), reloads last 20-TP memory |
| Pin 4 | A — RDAC terminal A (one end of resistor ladder) |
| Pin 5 | W — RDAC wiper terminal |
| Pin 6 | B — RDAC terminal B (other end of resistor ladder) |
| Pin 7 | SDO — SPI serial data output (daisy-chain) |
| Pin 8 | SDI — SPI serial data input |
| Pin 9 | SCLK — SPI serial clock |
| Pin 10 | SYNC — SPI frame synchronization (chip select, active low) |
| Pin 11 | VL — Logic supply voltage, 1.7 V to 5.5 V |
| Pin 12 | GND — Ground reference for logic supply |
| Pin 13 | RSVD — Reserved pin (do not connect) |
| Pin 14 | RSVD — Reserved pin (do not connect) |
Typical Applications
AD5291BRUZ-20 is suitable for 6 applications: Programmable Gain Instrumentation Amplifier, LCD Display Contrast and Backlight Adjustment, Audio Attenuator and Tone Control, Precision Reference Voltage Trimming, Programmable Filter Cutoff Frequency, Industrial 4–20 mA Loop Calibration.
Programmable Gain Instrumentation Amplifier
The AD5291BRUZ-20 is widely used as the gain-setting resistor in a programmable-gain instrumentation amplifier (PGIA) front-end. With 20 kΩ end-to-end and 256 taps, the part delivers a fine 78 Ω LSB step that lets a system trim closed-loop gain to ±0.5% accuracy using a simple lookup table. The integrated 20-TP nonvolatile memory preserves the calibrated gain through power-down, allowing factory-trimmed gain in multi-channel data-acquisition modules without external EEPROM. Unlike mechanical trimmers, the SPI-controlled wiper eliminates manual adjustment, lowers BOM cost, and supports remote calibration over a backplane. Operate the part from VDD=5 V and VL tied to the host MCU rail (3.3 V or 5 V) for a single-supply signal chain; ensure wiper current stays below 1 mA to avoid distortion in the rheostat-mode IPG5
Recommended
LCD Display Contrast and Backlight Adjustment
The AD5291BRUZ-20 is used to drive the contrast-adjustment pin of character and graphic LCDs, replacing mechanical trim pots with a digital control. The 256-position resolution translates to roughly 0.4% per step, more than enough for human-perceptible contrast tuning across temperature and viewing angle. The part's 5 ppm/°C nominal temperature coefficient keeps the contrast stable across the LCD's -20 °C to +70 °C operating range, eliminating the visible drift seen with carbon-film trimmers. Designers typically pair the AD5291BRUZ-20 with a single op-amp buffer to source the higher bias currents demanded by large TFT panels, since the 50 Ω wiper resistance limits continuous current to about 5 mA. The SPI bus permits the host MCU to update contrast on the fly in response to ambient-light sensor feedback, supporting automatic dimming in handheld and automotive dashboards
Recommended
Audio Attenuator and Tone Control
The AD5291BRUZ-20 is a good fit for line-level audio attenuators and simple tone-control circuits where a logarithmic volume curve is synthesized in firmware. Its 20 kΩ resistance keeps the wiper current low for typical line-level signals (≤2 Vrms), and the 50 Ω wiper resistance introduces negligible THD below 0.001%. System designers map the 256 linear taps to a pseudo-logarithmic dB curve in the MCU's firmware, yielding a perceived audio taper that matches human hearing. Because the AD5291BRUZ-20 is a passive resistor, it adds no active noise, preserving the SNR of the upstream DAC. For headphone drive (32 Ω loads) a dedicated audio volume IC such as the ADI SSM2163 is preferred; the AD5291BRUZ-20 is best deployed ahead of a headphone amplifier where it sets the line-level gain only
Recommended
Precision Reference Voltage Trimming
The AD5291BRUZ-20 is used to trim the output of precision voltage references such as the ADR01 or ADR02 to a target value within ±0.05%. A 20 kΩ digi-pot wired as a variable resistor in series with the reference's trim pin produces a fine 78 Ω adjustment step, far finer than a mechanical trimmer's typical 100 Ω per turn. After calibration the wiper position is committed to the 20-TP nonvolatile memory, so the part holds its trim through power cycles and reflow. The 5 ppm/°C temperature coefficient adds negligible drift to the reference, and the SPI interface allows in-system recalibration without opening the enclosure. This approach is common in 6½-digit DMMs, precision analog I/O modules, and laboratory calibrators where one-time factory calibration is required
Recommended
Programmable Filter Cutoff Frequency
The AD5291BRUZ-20 is used to set the cutoff frequency of active low-pass and high-pass filters in audio, instrumentation, and anti-aliasing applications. Replacing two fixed resistors with the digi-pot lets the host MCU sweep cutoff frequency in 256 steps over a 78 Ω LSB resolution, enabling software-tuned anti-aliasing or de-emphasis networks. The 5 ppm/°C temperature coefficient of the resistor ladder tracks well with the surrounding metal-film components, preserving filter Q across the -40 °C to +105 °C operating range. Designers should bias the wiper at mid-rail and limit signal swing to ±VDD to avoid distortion in the MOSFET switches. For higher-order filters or higher Q designs, two AD5291BRUZ-20 devices can be daisy-chained on SPI to control independent filter stages from a single host bus
Recommended
Industrial 4–20 mA Loop Calibration
The AD5291BRUZ-20 is used in 4–20 mA current-loop transmitters and receivers to calibrate zero-scale (4 mA) and full-scale (20 mA) trim. With 20 kΩ end-to-end and 256 taps, the digi-pot supplies 78 Ω steps at the loop-sense resistor, letting the host MCU trim loop accuracy to better than ±0.1% FS without manual adjustment. The nonvolatile memory preserves calibration through power cycles and brown-out events, critical for loop-powered 2-wire transmitters that can lose supply during fault conditions. The 1.7–5.5 V logic supply allows the part to be driven directly from a low-power MCU running on the loop's 3.3 V rail. Designers should add TVS protection at the loop terminals and place the AD5291BRUZ-20 close to the sense resistor to minimize ground-loop errors
Recommended
Recommended Products Summary
Engineering reference data for AD5291BRUZ-20 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD5291BRUZ-50 | AD5291BRUZ-100 | AD5292BRUZ-20 | AD5270BCPZ-20 |
|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 14-TSSOP (RU-14) | 14-TSSOP (RU-14) | 14-TSSOP (RU-14) | 14-TSSOP (RU-14) | 10-LFCSP (CP-10) |
| End-to-End Resistance (kΩ) | 20 | 50 | 100 | 20 | 20 |
| Number of Taps | 256 | 256 | 256 | 1024 | 1024 |
| Resistance Tolerance | ±1% | ±1% | ±1% | ±1% | ±1% |
| Digital Interface | SPI | SPI | SPI | SPI | I²C |
| Nonvolatile Memory (TP cycles) | 20 | 20 | 20 | 50 | 50 |
| Analog Supply (V) | 2.7 to 5.5 | 2.7 to 5.5 | 2.7 to 5.5 | 2.7 to 5.5 | 2.7 to 5.5 |
| Operating Temperature (°C) | -40 to +105 | -40 to +105 | -40 to +105 | -40 to +105 | -40 to +125 |
Key Differentiators
- Industry-leading ±1% end-to-end R-tolerance with 5 ppm/°C tempco (vs AD5270BCPZ-20)
- Single-supply 2.7–5.5 V analog with 1.7–5.5 V logic for direct MCU interface (vs MCP4131-203)
- 20-TP nonvolatile memory with hardware RESET pin (vs MAX5380)
Design Notes
Place the 0.1 µF VDD and VL decoupling capacitors within 5 mm of their respective supply pins, with the ground return trace routed directly to the nearest GND pin. According to the ADI AD5291/AD5292 datasheet, the analog (VDD) and logic (VL) supplies may be tied together if the system uses a single 3.3 V or 5 V rail; separate rails allow the digi-pot to interface to a low-voltage MCU while running the RDAC at 5 V. Avoid running digital SPI traces parallel to the resistor-ladder terminals A, W, and B to prevent digital noise coupling into the analog signal path.
Keep signal current through the RDAC wiper below 1 mA continuous to avoid contact-resistance drift and to stay within the part's specified linearity. For applications requiring higher current (for example, driving a heavy load directly), buffer the wiper output with a low-offset op-amp such as the AD8628. Estimated: wiper resistance is typically 50 Ω, so at 1 mA the wiper drops only 50 mV — well within the part's signal range but enough to introduce distortion if the application uses rheostat mode at high currents.
Do not exceed the absolute maximum rating of 6.5 V on VDD, and never let VL exceed VDD, as this will forward-bias internal ESD diodes and permanently damage the part. Do not apply a signal to terminal A, W, or B that exceeds VDD or goes below GND; the part has no internal over-voltage protection on the RDAC terminals. When writing to the 20-TP nonvolatile memory, allow the program cycle to complete (typically 50 ms) before issuing the next SPI command, or the write may be silently ignored. Reserve one NVM cycle for end-of-line calibration rather than burning cycles during development.
At maximum signal current of 1 mA through the RDAC and a worst-case end-to-end dissipation of 20 kΩ × (1 mA)² = 20 µW, self-heating is negligible. However, in 4-wire or current-loop applications where the digi-pot drops tens of volts, dissipation can reach several milliwatts — well within the 14-TSSOP's 90 °C/W θJA. No heatsink is required for typical instrumentation, audio, and contrast-control applications.
Compliance Information
RoHS and REACH compliant per Analog Devices product page. Lead-free (Pb-free) matte-tin finish. Not AEC-Q100 qualified — for automotive applications consider the AD5291 automotive-grade part numbers (consult ADI). Halogen-free per JESD22-A114.
