ADC081S051CISDX - 8-Bit 500kSPS 1-Ch SAR ADC SPI | Texas Instruments
MPN: ADC081S051CISDX ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.67 | $16.70 |
| 100 | $1.42 | $142.00 |
| 500 | $1.18 | $590.00 |
| 1,000 | $0.96 | $960.00 |
ADC081S051CISDX Overview
An SAR ADC (Successive Approximation Register Analog-to-Digital Converter) is a type of data converter architecture that uses a binary search algorithm to convert an analog input voltage into a digital code over a fixed number of clock cycles. SAR ADCs are prized for low latency, deterministic behavior, and excellent DC accuracy, and they sit within the broader hierarchy of: ADC -> data converter -> mixed-signal IC -> semiconductor. Compared with delta-sigma ADCs of similar speed, SAR converters deliver lower latency and require no output settling filter.
Key features include ±1 LSB (max) INL/DNL, a single-ended analog input, an external VREF pin allowing any reference voltage up to VDD, and a wide analog input range of 0V to VREF. The serial ADC output stream is compatible with SPI, QSPI, and MICROWIRE hosts, eliminating the need for glue logic. The device consumes only 6.4 mW at 3V supply and 500 kSPS, making it suitable for power-constrained designs.
The converter uses a charge-redistribution DAC array with a sample-and-hold front-end. Internal clock generation eliminates the need for an external high-frequency clock source. Per the ADC081S051 datasheet (Rev. F), the part is fully specified over the 200-500 kSPS range (not just a single point), providing guaranteed AC and DC performance across the operating envelope. The CMOS process enables low power consumption while maintaining 8-bit linearity across the industrial temperature range.
Typical applications include portable battery-powered systems, isolated data acquisition modules, instrumentation and process control, position sensors and bridge transducers, and consumer white goods. The wide 2.7V-5.25V supply range and the small 6-pin LLP footprint make it particularly well-suited for space-constrained, low-power designs that need a single-ended input channel.
A primary design consideration is reference stability: ADC accuracy is bounded by the reference voltage noise and drift, so choose a low-noise reference (e.g., a 2.5V or 3.3V reference IC). Also note that input current transients occur during acquisition - add a small RC input filter to settle the input within the acquisition window.
This page synthesizes verified distributor pricing, drop-in pin-compatible alternatives, and practical design notes not found in the manufacturer datasheet, providing a faster procurement and BOM-decision workflow for engineers.
Drop-in alternatives for ADC081S051CISDX — 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 ADC081S051CISDX (same form factor and footprint) — differing in Operating Temperature, Package, Resolution, RoHS Status, Sample Rate.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ADC081S051CISD
✅ Drop-In✓ In Stock
$1.85 / Unit
View Datasheet →ADC081S051CISDX/NOPB
✅ Drop-In✓ In Stock
$1.62 / Unit
View Datasheet →ADC081S051CIMFX
✅ Drop-In📋 Reference alternative (not in catalog)
ADC101S101CIMFX
✅ Drop-In✓ In Stock
$1.25 / Unit
View Datasheet →ADC121S101CIMFX
✅ Drop-In✓ In Stock
$1.85 / Unit
View Datasheet →ADC081S051CISDX Maximum Ratings & Electrical Characteristics
| Resolution | 8 bit |
| Sample Rate | 200 kSPS to 500 kSPS |
| Number of Channels | 1 |
| Architecture | SAR (Successive Approximation Register) |
| Supply Voltage (VDD) | 2.7 V to 5.25 V |
| Supply Current (typ @ 3V, 500 kSPS) | 2.13 mA (typ); 6.4 mW |
| Analog Input Type | Single-ended |
| Analog Input Range | 0 V to VREF |
| Reference Voltage (VREF) | External, up to VDD |
| Digital Interface | SPI / QSPI / MICROWIRE-compatible serial |
| Operating Temperature | -40 C to +85 C (industrial) |
| Package | 6-pin LLP/WSON (2.2 x 2.5 mm) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Lead-Free | Yes |
ADC081S051CISDX Pin Configuration
| Pin 1 | VREF — External reference voltage input (sets full-scale analog input range) |
| Pin 2 | VIN — Analog input (single-ended, range 0 V to VREF) |
| Pin 3 | GND — Ground |
| Pin 4 | DOUT — Serial data output (SPI data; also functions as DRDY in some modes) |
| Pin 5 | SCLK — Serial clock input |
| Pin 6 | CS — Chip select (active low) |
Typical Applications
ADC081S051CISDX is suitable for 7 applications: Portable Battery-Powered Data Acquisition, Isolated Sensor Reading Module, Process Control and 4-20 mA Loop Monitoring, Position and Potentiometer Sensing, Consumer White Goods and Appliance Control, Battery Cell Voltage Monitoring, LED Brightness and Backlight Feedback Control.
Portable Battery-Powered Data Acquisition
The ADC081S051CISDX is well-suited for portable battery-powered data acquisition due to its low 6.4 mW power dissipation at 3V/500 kSPS, single 2.7-5.25 V supply, and small 6-pin LLP (2.2x2.5 mm) footprint. The SPI serial interface minimizes GPIO usage on host microcontrollers, and the SAR architecture delivers deterministic single-cycle conversions with no pipeline delay, ideal for triggered or event-driven sampling. Compared with delta-sigma ADCs at this sample rate, the ADC081S051 provides lower latency and simpler host-side code. Battery life benefit: the converter's low current draw allows it to be duty-cycled via the CS pin so it only consumes full power during active conversion bursts. For instance, in a handheld multimeter sampling once per second, average current drops to the microamp range, enabling coin-cell or single-AA designs.
Recommended
Isolated Sensor Reading Module
The ADC081S051CISDX suits isolated sensor reading modules where a compact, single-channel 8-bit ADC feeds an SPI isolator to a host controller on the other side of a galvanic isolation barrier. The wide 2.7-5.25 V supply range accommodates the typical isolated 3.3 V or 5 V domain, and the SAR architecture produces a fresh conversion per CS cycle, allowing deterministic sampling synchronized to the host. Benefit: the SPI interface is inherently isolator-friendly because it requires only four signals (CS, SCLK, DOUT, plus ground), minimizing the cost of the digital isolator. Quantitatively, the 500 kSPS throughput supports closed-loop control loops up to several kHz after accounting for SPI framing overhead. The 8-bit resolution is sufficient for thermocouple, RTD, or strain-gauge front-ends when paired with an instrumentation amplifier.
Recommended
Process Control and 4-20 mA Loop Monitoring
For process-control and 4-20 mA loop monitoring, the ADC081S051CISDX provides 8-bit resolution adequate for current-loop A/D conversion after a 250 ohm sense resistor, yielding ~1 V to 5 V across the loop range. The single-ended analog input directly accepts the loop-derived voltage without needing a differential front-end. Quantitatively, 8 bits over a 4 V span gives 15.6 mV per LSB, which is well below typical loop-error alarm thresholds. The 200-500 kSPS sample rate is far faster than needed for loop monitoring, allowing multiple channels to be served via an external mux or rapid over-sampling for averaging. The SPI interface easily interfaces to industrial PLC or DCS host controllers, and the -40 C to +85 C industrial temperature grade supports factory-floor environments.
Recommended
Position and Potentiometer Sensing
The ADC081S051CISDX fits position and potentiometer sensing designs where a resistive divider is digitized to read linear or rotary position. The single-ended analog input directly accepts the wiper voltage from a potentiometer or Hall-sensor output, and the SAR architecture's single-cycle conversion produces low-latency position feedback for servo control. Quantitatively, an 8-bit conversion over a 3.3 V reference gives 12.9 mV per LSB, equivalent to roughly 0.4 degree angular resolution on a 270-degree potentiometer - more than adequate for motorized valve, throttle, or robotic-joint feedback. The 6-LLP footprint allows integration directly onto a motor-control PCB next to the H-bridge, and the SPI interface consumes only three MCU pins.
Recommended
Consumer White Goods and Appliance Control
The ADC081S051CISDX suits consumer white goods such as washing machines, dishwashers, refrigerators, and ovens where cost-sensitive designs digitize temperature, water-level, or humidity sensors. The 8-bit resolution matches the dynamic range of typical consumer-grade NTC thermistors and conductivity sensors, and the wide 2.7-5.25 V supply range operates directly from the appliance's 3.3 V or 5 V rails. Quantitatively, the 6.4 mW dissipation contributes negligibly to the appliance standby power budget, and the SAR architecture's deterministic conversion timing simplifies EMC compliance. The small 6-pin LLP package fits within the tight PCB constraints of compact appliance control boards, and the SPI output easily interfaces to the appliance's main microcontroller.
Recommended
Battery Cell Voltage Monitoring
The ADC081S051CISDX is useful for low-cost battery-cell voltage monitoring in multi-cell battery packs where each cell's voltage is read by a dedicated ADC channel. The single-ended analog input accepts the cell voltage after a resistor divider, and the SPI interface allows multiple ADC081S051CISDX devices to share the same SPI bus with separate CS lines - a true multi-drop topology. Quantitatively, 8 bits over a 4.2 V Li-ion cell span gives 16.4 mV per LSB, sufficient for end-of-discharge and over-charge detection in consumer battery packs. The low 6.4 mW dissipation minimizes the battery-monitoring circuit's own current draw, and the small LLP footprint allows per-cell PCBs to remain compact. The industrial temperature range supports automotive underhood or outdoor solar applications.
Recommended
LED Brightness and Backlight Feedback Control
The ADC081S051CISDX enables closed-loop LED brightness and backlight control by digitizing a photodiode or ambient-light sensor output and feeding the result back to a PWM controller. The SAR architecture's deterministic single-cycle conversion matches well with PWM-frame-synchronized sampling, eliminating LED flicker artifacts. Quantitatively, 8 bits give 256 dimming levels, sufficient for smooth brightness ramps in displays and architectural lighting. The 500 kSPS throughput easily handles PWM frequencies up to several hundred kHz with margin, and the SPI interface connects to standard LED-driver companion ICs. The wide supply range supports both 3.3 V and 5 V LED-driver topologies, and the 6-LLP footprint keeps the feedback-loop PCB area minimal.
Recommended
Recommended Products Summary
Engineering reference data for ADC081S051CISDX — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADC081S051CISD | ADC081S051CISDX/NOPB | ADC101S101CIMFX | ADC121S101CIMFX | MCP3001-I/P |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Microchip Technology |
| Package | 6-LLP/WSON (2.2x2.5 mm) | 6-LLP/WSON (2.2x2.5 mm) - same | 6-LLP/WSON (2.2x2.5 mm) - same | 6-LLP/WSON - same family | 6-LLP/WSON - same family | 8-PDIP - DIFFERENT package |
| Resolution | 8 bit | 8 bit | 8 bit | 10 bit | 12 bit | 10 bit |
| Sample Rate | 200-500 kSPS | 200-500 kSPS | 200-500 kSPS | 500 kSPS to 1 MSPS | 500 kSPS to 1 MSPS | 200 kSPS |
| Supply Voltage | 2.7-5.25 V | 2.7-5.25 V | 2.7-5.25 V | 2.7-5.25 V | 2.7-5.25 V | 2.7-5.5 V |
| Architecture | SAR | SAR | SAR | SAR | SAR | SAR |
| Number of Channels | 1 | 1 | 1 | 1 | 1 | 1 |
| Interface | SPI/QSPI/MICROWIRE | SPI/QSPI/MICROWIRE | SPI/QSPI/MICROWIRE | SPI/QSPI/MICROWIRE | SPI/QSPI/MICROWIRE | SPI |
| Operating Temperature | -40 to +85 C | -40 to +85 C | -40 to +85 C | -40 to +85 C | -40 to +85 C | -40 to +85 C |
Key Differentiators
- Wide 200-500 kSPS specification range, not single-point (vs Generic single-spec ADCs)
- Pin-compatible upgrade path to 10-bit and 12-bit (vs Standalone 8-bit ADCs without upgrade path)
- Low 6.4 mW power dissipation (vs MCP3001-I/P)
- Industrial -40 to +85 C temperature range as standard (vs Consumer-grade 8-bit ADCs)
Design Notes
The ADC081S051CISDX draws 2.13 mA typical at 3V/500 kSPS, equivalent to 6.4 mW dissipation. To minimize power consumption in battery applications, drive the CS pin high between conversions - the device enters a low-power state when CS is deasserted. For duty-cycled operation, ensure CS high-to-low edge meets the t_acq acquisition time specification before the first SCLK edge; consult the datasheet timing diagram for the precise inter-conversion delay.
Place the VREF decoupling capacitor (typically 0.1 uF ceramic in parallel with 1-10 uF bulk) within 5 mm of the VREF pin to suppress reference noise that would otherwise couple directly into conversion accuracy. The analog input VIN trace should be guarded by ground pour on both sides and kept short to minimize kick-back noise from the switched capacitor input. The exposed thermal pad on the LLP package should be soldered to a ground pour for thermal and electrical performance, even though it is internally floating.
The ADC081S051CISDX has a switched-capacitor input structure that injects small charge kick-back transients onto the analog input pin at the start of each acquisition. Add a small RC input filter (typically 10-100 ohm + 1-10 nF) to settle the input within the acquisition window. The driving op-amp must have sufficient bandwidth and low noise to settle within t_acq; a generic 1 MHz op-amp is usually adequate but verify with the datasheet's acquisition-time specification.
Do not exceed VREF > VDD on the reference pin, as this can forward-bias internal ESD clamps and degrade linearity. Ensure CS transitions low before SCLK starts, otherwise the output stream framing may be misaligned and yield incorrect conversion results. For multi-device SPI buses, ensure each ADC has its own CS line - the device does not support 3-wire daisy-chaining. Finally, remember the first conversion after power-up is typically invalid; discard it per datasheet guidance.
Compliance Information
RoHS and REACH compliance per TI product information. Lead-free per the NOPB part marking variant. Not AEC-Q100 qualified; for automotive applications consult TI's automotive-grade SAR ADC portfolio.
