ADC128S102 Selection Guide: How to Choose the Right 8-Channel 12-Bit SAR ADC
Compare ADC128S102 variants by supply voltage, temperature range, package, and qualification to pick the right 8-channel 12-bit SAR ADC for your design.
Last updated: June 2026
Bottom Line: Choosing the right 8-channel 12-bit SAR ADC for your design comes down to three factors: supply voltage and input range compatibility, sampling rate versus power budget, and environmental qualification level. The ADC128S102 family from Texas Instruments — including the commercial ADC128S102CIMT, the tape-and-reel ADC128S102CIMT/NOPB, the extended-supply ADC128S102WGMPR, and the radiation-hardened ADC128S102WGRQV — covers commercial, industrial, and space applications with a common SPI interface. This guide walks through every key selection parameter so you can confidently search for the right variant or request a quote without second-guessing your choice.
What Is the ADC128S102 Family?
The ADC128S102 is a CMOS 12-bit successive-approximation (SAR) ADC manufactured by Texas Instruments. It integrates eight single-ended input channels multiplexed to a single 12-bit converter core, all accessible over a 3-wire SPI-compatible serial interface. The device achieves up to 1 MSPS aggregate throughput, making it a popular choice for data acquisition systems, industrial process control, portable instruments, and motor control feedback.
The family spans multiple package and qualification tiers while preserving pin and software compatibility. Upgrading from a commercial variant to an automotive or radiation-hardened variant typically requires only a component swap, not a PCB redesign.
Key Selection Parameter 1: Supply Voltage and Analog Input Range
The ADC128S102 operates from a single supply (V_A = V_DD) in the range of 2.7 V to 5.25 V. The full-scale input range equals V_A, meaning you must match the supply voltage to the signal swing of your sensor or analog front end. For 3.3 V systems running low-power microcontrollers, select the 3.3 V supply option; for legacy 5 V systems or industrial sensors with 0–5 V output, use a 5 V supply.
All eight channels share the same reference derived from V_A, so there is no separate V_REF pin to worry about. If your signal chain requires a different reference voltage, you must scale the input externally before the ADC. This simplicity reduces BOM cost but limits flexibility compared to ADCs with external reference inputs.
The minimum input voltage on any channel is GND (0 V) and the maximum is V_A. Voltages outside this window may damage the input ESD structures — always verify your sensor output swing falls within the ADC supply range.
Key Selection Parameter 2: Sampling Rate and Throughput
The ADC128S102 supports a conversion clock (SCLK) range of 0.8 MHz to 3.2 MHz, corresponding to a per-channel throughput of 50 ksps to 200 ksps. With all eight channels sampled in round-robin fashion, aggregate throughput reaches up to 1 MSPS at the maximum SCLK frequency.
Each conversion requires 16 SCLK cycles: 4 don't-care cycles and 12 data cycles. You set the next channel address in the MSB of the 16-bit write word during the ongoing conversion, enabling seamless pipelined operation without idle cycles between channels.
For applications requiring synchronized multi-channel sampling — such as three-phase motor current sensing — note that the ADC128S102 samples channels sequentially, not simultaneously. If simultaneous sampling is mandatory, use a device with dedicated sample-and-hold stages per channel. For most industrial monitoring and data logging use cases, the sequential architecture is sufficient.
Key Selection Parameter 3: Resolution and Accuracy
The ADC128S102 provides 12-bit resolution (4096 codes), yielding a 1 LSB step of approximately 0.8 mV at 3.3 V supply or 1.2 mV at 5 V supply. Key static accuracy specifications at 5 V supply are:
- Integral non-linearity (INL): ±1 LSB typical, ±2 LSB maximum
- Differential non-linearity (DNL): ±0.5 LSB typical, ±1 LSB maximum (no missing codes guaranteed)
- Offset error: ±1 LSB typical
- Gain error: ±0.4% FSR typical
These specifications meet IEC 61000-series performance requirements for Class B industrial instruments. The no-missing-codes guarantee across the full input range simplifies firmware because you do not need to handle non-monotonic output.
For safety-critical systems requiring ADC diagnostics, consult the functional safety supplement; the ADC128S102 is not AEC-Q100 qualified (only the WGRQV radiation-hardened variant carries MIL-STD qualification).
Key Selection Parameter 4: Interface and Digital Logic Levels
The SPI interface operates in Mode 0 (CPOL = 0, CPHA = 0) and Mode 3 (CPOL = 1, CPHA = 1). The chip-select (CS_N) is active-low; data shifts in on the falling edge of CS_N with the first SCLK rising edge clocking data out. Digital I/O thresholds scale with V_A, so the device is 3.3 V and 5 V logic compatible without level shifters when powered from the same rail.
Maximum SCLK frequency is 3.2 MHz. This is lower than some modern SAR ADCs (which reach 20–80 MHz SCLK), but it is sufficient for most embedded microcontroller applications where SPI bus speed is not the bottleneck. DOUT is a push-pull driver capable of driving 10 pF trace capacitance without external buffering.
Key Selection Parameter 5: Package Options
| Variant | Package | Pins | Footprint |
|---|---|---|---|
| ADC128S102CIMT | TSSOP-16 | 16 | 4.4 mm × 5.1 mm |
| ADC128S102CIMT/NOPB | TSSOP-16 | 16 | 4.4 mm × 5.1 mm (tape-and-reel) |
| ADC128S102CIMTX/NOPB | TSSOP-16 | 16 | 4.4 mm × 5.1 mm (large reel, 2500 pcs) |
| ADC128S102WGMPR | WQFN-16 | 16 | 4.0 mm × 4.0 mm × 0.8 mm |
| ADC128S102WGRQV | WQFN-16 | 16 | 4.0 mm × 4.0 mm (rad-hard) |
The TSSOP-16 packages are preferred for manual assembly and prototyping due to 0.65 mm pitch leads. The WQFN-16 packages offer a 40% smaller footprint for space-constrained designs and have an exposed pad for improved thermal performance, though they require reflow soldering equipment.
All variants share the same 16-pin pinout, so switching between package types requires only a footprint update in your PCB layout — the schematic remains unchanged.
Key Selection Parameter 6: Temperature Range and Qualification
| Variant | Temperature Range | Target Market |
|---|---|---|
| ADC128S102CIMT / CIMT/NOPB / CIMTX/NOPB | 0 °C to +70 °C | Commercial/consumer electronics |
| ADC128S102WGMPR | −40 °C to +85 °C | Industrial, extended |
| ADC128S102WGRQV | −55 °C to +125 °C | Military, radiation-hardened space |
The WGRQV variant is radiation-hardened to MIL-STD-883 and meets JEDEC JESD57 guidelines for single-event effects (SEE), making it suitable for satellite payloads and high-altitude avionics. It is priced significantly higher than commercial variants, so reserve it for designs that genuinely operate in radiation environments.
For industrial automation equipment operating in −40 °C to +85 °C ambient (the IEC 60068-2 standard range for Category C environments), the ADC128S102WGMPR is the cost-effective choice.
Key Selection Parameter 7: Power Consumption
Power consumption scales linearly with supply voltage and SCLK frequency. Typical figures at 5 V supply:
- Normal conversion mode: 1.5 mW at 1 MSPS
- Power-down mode: 1 µA (device enters power-down automatically after the last CS_N rising edge if no new conversion starts within a defined interval)
The on-chip power management means no external enable pin is needed. For duty-cycled IoT applications, you can burst-sample eight channels and then allow the ADC to self-power-down between measurement intervals, achieving average currents well below 100 µA.
At 3.3 V supply, power drops to approximately 0.6 mW in normal operation, making the ADC128S102 suitable for battery-powered portable instruments complying with IEC 62133 (portable equipment safety).
Recommended Products Comparison Table
| Product | V_A Range | Temp Range | Package | Qualification | Best For |
|---|---|---|---|---|---|
| ADC128S102CIMT | 2.7–5.25 V | 0 to +70 °C | TSSOP-16 | Commercial | Lab instruments, consumer devices |
| ADC128S102CIMT/NOPB | 2.7–5.25 V | 0 to +70 °C | TSSOP-16 tape-and-reel | Commercial (RoHS) | Production runs, no Pb |
| ADC128S102WGMPR | 2.7–5.25 V | −40 to +85 °C | WQFN-16 tape-and-reel | Industrial | Factory automation, HVAC, IoT |
| ADC128S102WGRQV | 2.7–5.25 V | −55 to +125 °C | WQFN-16 | MIL-STD-883 / Rad-hard | Space, avionics, defense |
All four variants deliver the same 12-bit / 8-channel / 1 MSPS performance. Selection is driven entirely by temperature range, package preference, and qualification requirement.
Selection Decision Flowchart
Use this decision tree to identify your variant in under a minute:
Does your system operate below 0 °C or above 70 °C?
- No → Go to Step 2
- Yes → Go to Step 3
Do you need tape-and-reel packaging for automated assembly?
- No → Select ADC128S102CIMT (tube packaging)
- Yes → Select ADC128S102CIMT/NOPB (tape-and-reel, RoHS)
Does the system operate in a radiation environment (satellite, avionics, defense)?
- Yes → Select ADC128S102WGRQV (rad-hard, −55 °C to +125 °C)
- No → Does the ambient temperature exceed +85 °C?
- Yes → ADC128S102WGRQV (only option with >+85 °C rating)
- No → ADC128S102WGMPR (industrial, −40 °C to +85 °C, WQFN-16)
Do you prefer the smallest PCB footprint?
- Yes → Favor WGMPR (WQFN-16, 4.0 × 4.0 mm) over the TSSOP-16 variants
Following this flowchart takes under 60 seconds and avoids the most common mistake: using a commercial-temp part in an industrial environment and encountering drift failures after production deployment.
FAQ
What is the maximum sampling rate of the ADC128S102?
The ADC128S102 achieves a maximum aggregate throughput of 1 MSPS across all eight channels combined. At a 3.2 MHz SCLK, each 16-cycle conversion completes in 5 µs, so each individual channel is sampled at up to 200 ksps when channels are sampled sequentially in round-robin order.
Is the ADC128S102 compatible with 3.3 V microcontrollers?
Yes. When powered from a 3.3 V supply, the ADC128S102 digital I/O thresholds scale with V_A. The logic high threshold (V_IH) is 0.7 × V_A = 2.31 V, and V_IL is 0.3 × V_A = 0.99 V, which is directly compatible with standard 3.3 V CMOS GPIO outputs. No level shifter is required.
What is the difference between ADC128S102CIMT and ADC128S102CIMT/NOPB?
The only difference is packaging format and RoHS compliance marking. The /NOPB suffix indicates "No Lead, No Pb" — the device uses lead-free (RoHS-compliant) solder terminations and is shipped in tape-and-reel format. The core silicon die and electrical specifications are identical.
Can I use multiple ADC128S102 devices on the same SPI bus?
Yes. Each device has a dedicated chip-select (CS_N) pin. Connect all devices to the same SCLK, DIN, and DOUT lines, and route individual CS_N signals from separate GPIO pins on your microcontroller. The push-pull DOUT driver requires that only one CS_N be asserted low at a time to avoid bus contention.
Is the ADC128S102 suitable for automotive applications?
The commercial (CIMT) and industrial (WGMPR) variants are not AEC-Q100 qualified and are not recommended for automotive safety systems. The radiation-hardened WGRQV variant meets MIL-STD-883 but is also not AEC-Q100 certified. For automotive ADC applications, Texas Instruments offers the ADS7028-Q1 and ADS8688A-Q1 families, which carry AEC-Q100 Grade 0 or Grade 1 qualification.
Conclusion and Next Steps
The ADC128S102 family delivers a proven 8-channel 12-bit SAR ADC solution with a common hardware and software interface across commercial, industrial, and radiation-hardened tiers. For most new industrial designs, the ADC128S102WGMPR offers the best balance of temperature performance, package density, and cost. For high-volume commercial builds, the ADC128S102CIMT/NOPB in tape-and-reel keeps BOM costs low. Space and defense programs requiring radiation immunity should specify the ADC128S102WGRQV.
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