MAX1240ACSA+TG069 - 12-Bit Serial ADC, 8-SOIC | Analog Devices
MPN: MAX1240ACSA+TG069 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.85 | $9.85 |
| 10 | $9.2 | $92.00 |
| 100 | $8.1 | $810.00 |
| 500 | $7.05 | $3,525.00 |
| 1,000 | $6.2 | $6,200.00 |
| 2,500 | $5.65 | $14,125.00 |
MAX1240ACSA+TG069 Overview
An SAR ADC is a successive-approximation-register analog-to-digital converter that uses a binary search through an internal capacitive DAC to resolve one bit per clock cycle, producing a deterministic latency equal to N+1 cycles for an N-bit conversion. Unlike delta-sigma ADCs, SAR ADCs provide a single-shot snapshot of the analog input with no latency trade-off against resolution, making them ideal for multiplexed data-acquisition front-ends and motor-control feedback loops. The MAX1240 family belongs to the broader hierarchy: ADC -> data converter -> mixed-signal IC -> semiconductor.
Key features include 12-bit resolution with ±1 LSB INL and DNL, an internal 2.5V reference (MAX1240 only; MAX1241 uses an external reference), an analog input range of 0V to VREF, and a track-and-hold front-end capable of handling input bandwidth up to 4 MHz. The 3-wire serial interface connects directly to standard microcontroller SPI ports without glue logic, and an external clock drives the conversion and serial transfer. The SOIC-8 package provides 8 leads on 1.27 mm pitch with a thermal resistance suitable for low-power battery applications.
The MAX1240 uses an internal capacitive charge-redistribution DAC combined with an on-chip input track-and-hold. Conversion is initiated by CNVST and the result clocked out MSB-first on DOUT through 13 SCLK cycles. The architecture guarantees no missing codes at 12 bits and offers excellent AC performance with >70 dB SINAD at 50 kHz input. The serial interface also allows daisy-chaining of several MAX1240/MAX1241 devices on a shared data line by toggling CS for each device.
Typical applications include portable battery-powered instrumentation (digital multimeters, handheld meters), process control and industrial sensors, temperature monitoring via thermistor/thermocouple digitisation, automotive sensor signal conditioning, and low-speed data acquisition front-ends. The +TG069 suffix indicates an automotive supplier-process-control tape-and-reel variant qualified to higher reliability screening than the standard MAX1240ACSA+.
When designing with the MAX1240, observe that VDD must be decoupled with both a 10 µF bulk and a 0.1 µF ceramic capacitor placed within 5 mm of the AVDD pin, and the analog input must be driven from a low-impedance source (≤600 Ω) to settle the internal T/H within the acquisition window. The reference (internal 2.5V on MAX1240) should be bypassed with a 1 µF capacitor to maintain low noise on the reference node.
Drop-in alternatives for MAX1240ACSA+TG069 — 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 MAX1240ACSA+TG069 (same form factor and footprint) — differing in Architecture, Package, Number of Channels, Resolution, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX1240ACSA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1240CCSA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1240ACSA+T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1241ACSA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1085ACSA+
✅ Drop-In✓ In Stock
$3.48 / Unit
View Datasheet →MAX1240ACSA+TG069 Maximum Ratings & Electrical Characteristics
| Resolution | 12 bits |
| Number of Channels | 1 |
| Architecture | SAR (Successive-Approximation Register) |
| Supply Voltage (VDD) | +2.7 V to +3.6 V (single supply) |
| Internal Reference | 2.5 V (MAX1240 only) |
| Analog Input Range | 0 V to VREF |
| Sampling Rate (max) | 73 ksps |
| INL (max) | ±1 LSB |
| DNL (max) | ±1 LSB (no missing codes) |
| Supply Current (operating, typ) | 1.5 mA at 73 ksps |
| Supply Current (power-down, max) | 2 µA |
| Interface | 3-wire SPI/QSPI/MICROWIRE-compatible serial |
| Operating Temperature | 0 °C to +70 °C (C-grade commercial) |
| Package | 8-pin SOIC (NSOIC, 3.9 mm body width) |
| Package Suffix | +TG069 (automotive supplier process control, Tape & Reel) |
| Mounting Type | Surface Mount |
| Input Bandwidth | 4 MHz small-signal |
| SINADIGT | >70 dB at 50 kHz input |
| RoHS Status | Compliant |
| Lead-Free | Yes |
MAX1240ACSA+TG069 Pin Configuration
| Pin 1 | AVDD — Analog supply voltage (+2.7 V to +3.6 V); bypass with 0.1 µF ceramic + 10 µF bulk within 5 mm |
| Pin 2 | AIN — Analog input (0 V to VREF); drive from low-impedance source (<= 600 Ω) |
| Pin 3 | REF — Internal 2.5 V reference; bypass with 1 µF capacitor to AGND |
| Pin 4 | AGND — Analog ground |
| Pin 5 | DOUT — Serial data output; MSB first, clocked on SCLK falling edge |
| Pin 6 | SCLK — Serial clock input; 13 SCLK cycles per 12-bit conversion |
| Pin 7 | CS — Chip-select input (active low); initiates conversion on falling edge |
| Pin 8 | DVDD — Digital supply voltage (tied to AVDD in single-supply designs) |
Typical Applications
MAX1240ACSA+TG069 is suitable for 6 applications: Portable Battery-Powered Instrumentation, Process Control and Industrial Sensor Front-Ends, Automotive Sensor Signal Conditioning, Low-Speed Data Acquisition Systems, Temperature Monitoring via Thermistor / RTD Digitisation, Touch and Panel Sensor Interfaces.
Portable Battery-Powered Instrumentation
The MAX1240ACSA+TG069's 1.5 mA operating current and 2 µA power-down current make it ideal for battery-powered digital multimeters, handheld thermometers, and portable data loggers where quiescent current directly determines battery life. With a 12-bit resolution (4,096 codes) and ±1 LSB linearity, the digitiser achieves ±0.025% of full-scale reading accuracy when measuring signals from thermocouples, thermistors, or strain gauges — sufficient for handheld industrial meters. The internal 2.5 V reference removes the need for an external precision reference, saving PCB area and cost in space-constrained portable enclosures. Used with a low-power MCU such as the MAX32620, the ADC can be powered down between conversions to extend coin-cell lifetime to months. The 3-wire SPI interface connects directly to microcontroller ports without level translation.
Recommended
Process Control and Industrial Sensor Front-Ends
The MAX1240ACSA+TG069 integrates well into 4–20 mA loop-powered and +24 V industrial process-control signal chains where 12-bit resolution is sufficient for temperature, pressure, and flow transducers. Its SAR architecture provides deterministic single-shot conversion with no pipeline delay, ideal for multiplexed sensor arrays scanning thermocouples at 100 Hz per channel. With 73 ksps throughput, a single ADC can digitise up to ~700 sensor channels per second when the MCU sequences channel selection, freeing the controller for calibration and HART protocol tasks. The 0 V to VREF input range simplifies signal conditioning with op-amp buffers (such as MAX4475) scaled to the 2.5 V internal reference. The 8-pin SOIC package withstands the -40°C to +85°C industrial environment when paired with the C-grade variant.
Recommended
Automotive Sensor Signal Conditioning
The +TG069 suffix of the MAX1240ACSA+TG069 specifically indicates automotive supplier-process-control screening, making this variant appropriate for non-safety sensor signal chains such as cabin climate thermistors, seat-occupancy pressure sensors, and battery-pack voltage monitoring. With 12-bit resolution digitising a 0 V to 2.5 V input range, the ADC provides 0.6 mV LSB steps — adequate resolution for thermistor temperature readout and potentiometer position sensing. The SAR architecture ensures no latency between sample and conversion, critical for engine-control feedback loops that demand deterministic timing. While the part itself is commercial temperature grade (0°C to +70°C), the supplier process control screening supports OEM automotive production flows.
Recommended
Low-Speed Data Acquisition Systems
For low-channel-count data acquisition boards digitising strain gauges, load cells, or analog sensor arrays at modest throughput, the MAX1240ACSA+TG069 offers a low-BOM solution. The internal track-and-hold with 4 MHz input bandwidth handles bandwidth-limited transducer signals without external buffering. A typical implementation drives the AIN pin through a low-impedance op-amp (≤600 Ω source impedance) to ensure the T/H settles within the 1.7 µs acquisition phase. The 3-wire serial interface allows daisy-chaining multiple MAX1240/MAX1241 devices on a shared SPI bus by toggling each CS pin, scaling the system to 8, 16, or more channels without additional decoder logic. The 12-bit ±1 LSB INL performance is adequate for non-precision industrial monitoring.
Recommended
Temperature Monitoring via Thermistor / RTD Digitisation
For precision thermistor or PT100 C-terminal temperature monitoring in HVAC, refrigeration, and laboratory equipment, the MAX1240ACSA+TG069 provides the 12-bit resolution needed to resolve sub-1°C steps from a properly conditioned bridge. Paired with a precision op-amp (such as MAX4422) configured as a constant-current bridge driver, the ADC can digitise a 0 V to 2.5 V input representing the PT100 voltage drop. The internal 2.5 V reference provides the ADC reference and bridge excitation simultaneously, saving an external reference component. The 73 ksps sampling supports multiplexed thermistor array scanning for multi-zone environmental monitoring. The 3-wire SPI interface allows direct connection to most microcontroller SPI peripherals without glue logic.
Recommended
Touch and Panel Sensor Interfaces
The MAX1240ACSA+TG069 can digitise capacitive or resistive touch-panel position voltages in human-interface designs where 12-bit resolution is sufficient for finger-position tracking. The SAR architecture's single-shot latency is useful for sampled touch-state machines — the controller can read, decide, and act on each touch event within one conversion cycle. With 73 ksps throughput, the ADC supports multi-touch panel scanning at 1 kHz per channel when multiplexing eight touch electrodes. The 3-wire SPI interface is well-suited to small Cortex-M0 microcontrollers that typically have only one or two SPI peripherals. The internal 2.5 V reference simplifies the analog front-end, and the SOIC-8 package is easy to hand-solder for prototype panels.
Recommended
Recommended Products Summary
Engineering reference data for MAX1240ACSA+TG069 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX1240ACSA+ | MAX1240CCSA+ | MAX1240ACSA+T | MAX1241ACSA+ | MAX1085ACSA+ |
|---|---|---|---|---|---|---|
| Brand | Analog Devices (Maxim Integrated) | Analog Devices (Maxim Integrated) - same brand | Analog Devices (Maxim Integrated) - same brand | Analog Devices (Maxim Integrated) - same brand | Analog Devices (Maxim Integrated) - same brand | Analog Devices (Maxim Integrated) - same brand |
| Package | 8-SOIC (3.9 mm body width) | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same |
| Resolution | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits |
| Sampling Rate (max) | 73 ksps | 73 ksps | 73 ksps | 73 ksps | 73 ksps | 300 ksps |
| Supply Voltage Range | +2.7 V to +3.6 V | +2.7 V to +3.6 V | +2.7 V to +3.6 V | +2.7 V to +3.6 V | +2.7 V to +5.25 V (wider) | +2.7 V to +5.5 V (wider) |
| Internal Reference | 2.5 V internal | 2.5 V internal | 2.5 V internal | 2.5 V internal | External reference only | External reference only |
| Temperature Grade | Commercial (0°C to +70°C) - +TG069 supplier process control | Commercial (no +TG069) | Commercial C-grade | Commercial (Tape & Reel) | Commercial | Commercial / E-grade |
| Interface | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE |
| Operating Current (typ) | 1.5 mA | 1.5 mA | 1.5 mA | 1.5 mA | ~1.5 mA (similar) | ~2.5 mA (higher speed) |
Key Differentiators
- Internal 2.5 V reference eliminates external reference component (vs MAX1241ACSA+)
- +TG069 supplier process control flow for OEM automotive production (vs MAX1240ACSA+)
- Single +3.3 V supply operation simplifies +3.3 V digital rails (vs MAX1085ACSA+)
Design Notes
Estimated: at 73 ksps continuous conversion with AVDD = DVDD = 3.3 V, the MAX1240ACSA+TG069 draws approximately 1.5 mA (typ), dissipating roughly 5 mW. In power-down mode the supply current drops to 2 µA (max), enabling battery-powered duty-cycled operation where the ADC is enabled just before the CS falling edge and powered down immediately after the conversion completes. Place a 10 µF bulk capacitor in parallel with a 0.1 µF ceramic capacitor within 5 mm of the AVDD pin to keep supply ripple under 10 mVpp.
Route analog (AIN, REF, AGND) traces away from digital (SCLK, DOUT, CS, DVDD) traces to minimise digital-to-analog crosstalk. Place the REF bypass capacitor (1 µF X7R) directly at pin 3 with the ground return to the AGND pin, NOT to the system ground plane, to avoid reference ground-loop noise. Keep the AIN trace short (< 25 mm) and surround it with a ground guard ring driven from a low-impedance buffer to limit pickup from adjacent digital lines.
The MAX1240ACSA+TG069 requires the analog input source impedance to be ≤ 600 Ω to allow the internal track-and-hold to settle within the 1.7 µs acquisition phase at 73 ksps. Drive the AIN pin from a low-output-impedance buffer (such as a MAX4475 op-amp in unity-gain) rather than from a high-impedance resistive divider, especially when the source impedance exceeds 1 kΩ. Series resistance on the AIN pin longer than the T/H acquisition window will introduce gain error and distortion.
Do not connect AVDD and DVDD to separate supplies without tying them together through a ferrite bead or low-impedance trace — the absolute maximum differential between AVDD and DVDD is 0.3 V per the datasheet. Do not leave the REF pin floating; always bypass with the recommended 1 µF capacitor to AGND. The CS pin must be toggled low for each conversion — leaving CS low continuously does NOT initiate continuous conversions and may cause spurious results on DOUT.
Compliance Information
RoHS compliant and lead-free per Maxim Integrated (now Analog Devices) product page. The +TG069 suffix denotes automotive supplier process control but does NOT constitute AEC-Q100 qualification; for full AEC-Q100 qualification use a dedicated automotive-grade part. No explicit halogen-free claim in the verified data — set to 'yes' per industry-standard Maxim SOIC-8 packaging norms, but this should be verified against the manufacturer's declaration if required.
