MAX145AEPA - 12-Bit 108ksps 2-Ch Serial ADC | Analog Devices
MPN: MAX145AEPA ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.88 | $9.88 |
| 10 | $8.95 | $89.50 |
| 100 | $7.62 | $762.00 |
| 500 | $6.45 | $3,225.00 |
| 1,000 | $5.2 | $5,200.00 |
MAX145AEPA Overview
What is a SAR ADC? A successive-approximation-register analog-to-digital converter is a precision ADC architecture that uses a binary-search algorithm against an internal DAC to resolve an analog sample one bit at a time over N conversion cycles for N-bit resolution. SAR ADCs occupy the middle ground between flash ADCs (very fast, high power, low resolution) and sigma-delta ADCs (high resolution, lower bandwidth): they deliver medium-to-high resolution (12-18 bits typical) at medium-to-high speed (tens to thousands of ksps) with no pipeline latency, making them ideal for multiplexed multi-channel data acquisition, instrumentation, and control-loop sampling. SAR ADCs belong to the data-converter IC family, which sits inside the broader mixed-signal and power-management hierarchy of an embedded system.
Key features include 108ksps throughput, ±1 LSB (max) integral nonlinearity (INL), ±0.5 LSB differential nonlinearity (DNL, no missing codes), a true-differential analog input stage on the MAX145 (single-ended on MAX144), and 3.2mW active power consumption at VDD = +3.6V dropping to under 10uA in shutdown. The 8-pin DIP footprint enables easy through-hole prototyping, breadboarding, and repair-friendly designs where hand-soldering or socket-mounting is preferred over SMD. The MAX145AEPA is a popular drop-in companion to the MAX144AEPA for designs that need true-differential inputs at the same 12-bit resolution and serial interface.
Typical applications include handheld multimeters and test instruments, portable battery-powered sensor readout boards, industrial process-control loops, panel meters, temperature/voltage data loggers, and portable medical monitoring. The wide supply range (2.7V to 5.25V) lets a single part serve both 3.3V microcontroller rails and 5V analog front ends without level-shifting.
When designing with the MAX145AEPA, place 0.1uF bypass capacitors close to the AVDD and DVDD pins (these are tied together on the 8-pin DIP) and ensure the SPI SCLK line is free of glitches because the device lacks an SCLK noise filter. Use the active-low SHDN pin to drop quiescent current below 10uA between conversions in battery-powered designs.
Drop-in alternatives for MAX145AEPA — 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 MAX145AEPA (same form factor and footprint) — differing in Input Type, Mounting Type, RoHS Status, Analog Supply Voltage, Conversion Time.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX145AEPA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX145BEPA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX144AEPA
✅ Drop-In📋 Reference alternative (not in catalog)
MAX144AEPA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX145CEPA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1240BEPA+
✅ Drop-In✓ In Stock
$5.55 / Unit
View Datasheet →MAX145AEPA Maximum Ratings & Electrical Characteristics
| Part Number | MAX145AEPA |
| Manufacturer | Analog Devices (formerly Maxim Integrated) |
| Function | 12-bit 2-channel SAR analog-to-digital converter (ADC) |
| Resolution | 12 bits |
| Number of Channels | 2 |
| Sampling Rate (Throughput) | 108 ksps |
| Conversion Architecture | Successive-approximation (SAR) |
| Conversion Time | 7.4 us (typical) |
| Wake-Up Time | 2.5 us |
| Input Type | True differential (MAX145) / single-ended selectable (MAX144) |
| Supply Voltage (VDD) | +2.7 V to +5.25 V (single supply) |
| Active Power Consumption | 3.2 mW at VDD = +3.6 V |
| Shutdown Current | < 10 uA (auto power-down) |
| Integral Nonlinearity (INL) | ±1 LSB (max) |
| Differential Nonlinearity (DNL) | ±0.5 LSB (max, no missing codes) |
| Digital Interface | 3-wire SPI / QSPI / MICROWIRE-compatible serial |
| Operating Temperature Range | -40 C to +85 C (E suffix = industrial) |
| Package / Case | 8-pin PDIP (0.300 inch / 7.62 mm body) |
| Mounting Type | Through-Hole (THT) |
| Internal Reference | +2.5 V |
| RoHS Status | Non-RoHS (pre-2011 vintage product; + variant is RoHS) |
MAX145AEPA Pin Configuration
| Pin 1 | VDD — Power supply input, +2.7 V to +5.25 V; connect 0.1 uF bypass capacitor to GND close to the pin |
| Pin 2 | IN+ — Positive differential analog input (channel 1 / channel A) |
| Pin 3 | IN- — Negative differential analog input (channel 1 / channel A); return path for IN+ |
| Pin 4 | GND — Analog and digital ground return |
| Pin 5 | REF — Reference voltage input/output; internal 2.5 V reference, or connect external reference |
| Pin 6 | DOUT — Serial data output; 12-bit ADC result clocked out MSB-first on SCLK falling edges |
| Pin 7 | SCLK — Serial clock input; up to 4.9152 MHz, 3-wire SPI/QSPI/MICROWIRE-compatible |
| Pin 8 | CS — Active-low chip-select input; logic low enables the serial interface, logic high places DOUT in high-Z |
Typical Applications
MAX145AEPA is suitable for 6 applications: Handheld Digital Multimeter (DMM), Portable Battery-Powered Sensor Readout, Industrial Process-Control Loop, Temperature / Voltage Data Logger, Panel Meter / Instrumentation Display, Portable Medical Monitoring Device.
Handheld Digital Multimeter (DMM)
The MAX145AEPA's 12-bit resolution and 108 ksps throughput make it well-suited to the measurement channels of a handheld DMM, where the true-differential inputs can read the voltage across a shunt resistor for current measurement while rejecting common-mode ground noise. Its 3.2 mW active power at VDD = 3.6 V keeps battery drain low, while the < 10 uA automatic power-down between conversions enables months of standby life on a 9 V battery. The 3-wire SPI interface connects directly to an MCU without glue logic. Compared with sigma-delta alternatives at this bandwidth, the SAR architecture gives a single-shot conversion with no digital filter settling delay, so range-change response is immediate.
Recommended
Portable Battery-Powered Sensor Readout
The MAX145AEPA's +2.7 V to +5.25 V single-supply operation lets it digitize both 3.3 V microcontroller-rail sensors and 5 V analog front ends without level shifting, while its 2.5 us wake-up from auto-shutdown enables duty-cycled sampling that draws microamp-level average current. The true-differential inputs pair naturally with bridge-type sensors (load cells, strain gauges, pressure transducers), providing first-order common-mode rejection at the ADC. The 108 ksps throughput handles multiple multiplexed transducer channels in burst mode. Compared with sigma-delta ADCs in the same power class, the MAX145AEPA delivers lower latency and a simpler SPI interface with no decimation filter tuning.
Recommended
Industrial Process-Control Loop
The MAX145AEPA's -40 C to +85 C industrial temperature range and 12-bit no-missing-codes performance suit 4-20 mA loop receivers, panel meters, and PLC analog input modules operating on factory floors. The true-differential input simplifies interface to instrumentation amplifiers and 4-20 mA loop sense resistors, providing common-mode noise rejection in noisy industrial environments. The 108 ksps sampling rate oversamples typical control loops by 100x, enabling digital filtering at the MCU without aliasing. Compared with integrating ADCs (e.g. ICL7135) used historically in panels, the MAX145AEPA delivers a digital-output word directly via SPI, eliminating the MCU's counter/timer burden.
Recommended
Temperature / Voltage Data Logger
The MAX145AEPA's low active power (3.2 mW at VDD = 3.6 V) and sub-10 uA auto-power-down make it a strong fit for battery-powered data loggers that wake periodically, sample a sensor, and return to sleep. With a 2.5 us wake-up from shutdown, the part can support sub-millisecond active duty cycles at sample rates of 1-100 Hz, giving years of battery life from a single coin cell. The 2-channel differential input handles two thermocouples or two voltage probes simultaneously. The internal 2.5 V reference simplifies the bill of materials by removing an external reference IC. Compared with integrated MCU+ADC SoCs, the discrete MAX145AEPA gives the designer freedom to choose the MCU, flash, and battery chemistry independently.
Recommended
Panel Meter / Instrumentation Display
The MAX145AEPA's 12-bit resolution over a 0-2.5 V input range (using the internal reference) gives 0.6 mV LSB - sufficient for 3.5-digit (1999 count) and 4-digit (19999 count with scaling) panel meter displays. The differential input simplifies interface to current-shunt-based ammeter and bridge-based voltmeter designs. The 108 ksps throughput provides rapid display update rates, while SPI output drives the MCU that drives the LCD/LED display. Compared with legacy ICL7106/ICL7135 integrating ADC panel-meter ICs, the MAX145AEPA delivers a digital SPI word instead of multiplexed BCD segments, giving more flexible display formatting and easier calibration storage.
Recommended
Portable Medical Monitoring Device
The MAX145AEPA's low power (3.2 mW active, < 10 uA shutdown) and small 8-pin PDIP footprint support battery-powered, handheld medical devices such as pulse oximeters, blood-pressure monitors, and single-channel ECG front ends where board space and battery life are critical. The differential input pairs well with biopotential electrode front ends, providing common-mode rejection of 50/60 Hz mains interference at the ADC input. The 108 ksps throughput oversamples the physiological signal bandwidth (typically DC-100 Hz), enabling digital filtering. Compared with integrated analog-front-end SoCs, the discrete MAX145AEPA gives medical-device designers full control over the signal chain for IEC 60601 compliance verification.
Recommended
Recommended Products Summary
Engineering reference data for MAX145AEPA — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX145AEPA+ | MAX145BEPA+ | MAX144AEPA | MAX144AEPA+ | MAX145CEPA+ | MAX1240BEPA+ |
|---|---|---|---|---|---|---|---|
| Brand | Analog Devices (Maxim Integrated) | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | PDIP-8 (PA8, 0.300") | PDIP-8 (PA8, 0.300") - same | PDIP-8 (PA8, 0.300") - same | PDIP-8 (PA8, 0.300") - same | PDIP-8 (PA8, 0.300") - same | PDIP-8 (PA8, 0.300") - same | PDIP-8 (PA8, 0.300") - same |
| Resolution | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits |
| Sampling Rate | 108 ksps | 108 ksps | 108 ksps | 108 ksps | 108 ksps | 108 ksps | 73 ksps (-32%) |
| Input Channels | 2 (true differential) | 2 (true differential) | 2 (true differential) | 2 (single-ended) | 2 (single-ended) | 2 (true differential) | 1 (single-ended) |
| Supply Voltage | +2.7 V to +5.25 V | +2.7 V to +5.25 V | +2.7 V to +5.25 V | +2.7 V to +5.25 V | +2.7 V to +5.25 V | +2.7 V to +5.25 V | +2.7 V to +5.25 V |
| Interface | SPI / QSPI / MICROWIRE (3-wire) | SPI / QSPI / MICROWIRE | SPI / QSPI / MICROWIRE | SPI / QSPI / MICROWIRE | SPI / QSPI / MICROWIRE | SPI / QSPI / MICROWIRE | SPI (serial) |
| Operating Temperature | -40 C to +85 C (industrial) | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| RoHS Compliance | Non-RoHS (legacy) | RoHS-compliant | RoHS-compliant | Non-RoHS (legacy) | RoHS-compliant | RoHS-compliant | RoHS-compliant |
Key Differentiators
- True-differential input stage (vs MAX144AEPA+)
- Highest in-family throughput (108 ksps) (vs MAX1240BEPA+)
- Industrial -40 C to +85 C operating range (vs MAX145BCPA (commercial-grade))
- Internal 2.5 V reference (vs MAX1243ACPA)
Design Notes
Place a 0.1 uF low-ESR ceramic bypass capacitor within 5 mm of pin 1 (VDD) and pin 4 (GND); add a 10 uF tantalum or ceramic bulk capacitor if the supply trace exceeds 50 mm or shares a switching regulator with digital loads. The MAX145AEPA draws 3.2 mW active and < 10 uA in shutdown, so the bulk cap value is rarely critical, but the local 0.1 uF is mandatory to prevent digital-switching noise on VDD from coupling into the analog input through the internal reference. Estimated: with no bypass cap, a 50 mV VDD ripple at 100 kHz can inject ~0.5 LSB error at the ADC input.
Route the IN+ / IN- differential pair as a tightly-coupled, length-matched trace pair from the input source to pins 2 and 3, keeping them away from the SCLK (pin 7) and DOUT (pin 6) digital lines. Place a ground plane directly under the differential pair to maximize common-mode rejection; avoid crossing the analog input pair over any digital trace or split the ground plane under the ADC. The REF pin (pin 5) should be locally bypassed with a 1 uF to 10 uF low-ESR capacitor even when using the internal 2.5 V reference, because the reference buffer must drive dynamic charge during conversion.
Do not leave the SHDN/CS pin floating - if the MCU (S/H) GPIO is high-impedance during reset, the chip may either fail to power down or mis-trigger conversions. Tie CS high through a 100 kohm resistor to VDD so the part is disabled by default. Also note that the MAX145AEPA serial output is MSB-first; many other Maxim ADCs are LSB-first, so port code carefully when reusing firmware. The internal 2.5 V reference has limited drive capability and cannot source more than a few hundred microamps - do not use it to bias external circuitry.
When using the 8-pin PDIP (0.300 inch) footprint, allow a standard 2.54 mm (100 mil) pad pitch and a 0.9 mm (35 mil) drill for through-hole insertion. Keep at least 1.5 mm clearance around the package for hand-soldering or IC-socket insertion; an 8-pin DIP socket (e.g. Mill-Max 110-0084) is recommended for prototype boards. Because the PDIP is through-hole, the thermal resistance theta_JA is approximately 100 C/W (estimated, based on standard PDIP-8 packaging), giving negligible self-heating at the 3.2 mW operating power.
Compliance Information
MAX145AEPA is the legacy non-RoHS ordering code; the RoHS-compliant + suffix variant (MAX145AEPA+) is recommended for new designs. Per Maxim/ADI documentation, the original -8 suffix parts contain lead finish that is not RoHS-compliant. AEC-Q100 automotive qualification is not specified for this industrial-temperature part; for automotive applications, consult ADI for current automotive-qualified SAR ADC options.
