MAX1240BEPA+ - 12-Bit 73ksps SPI ADC, External Ref | Maxim
MPN： MAX1240BEPA+ ✓ 啟用中MAX1240BEPA+ 概覽
An SAR (Successive Approximation Register) ADC is a type of analog-to-digital converter that uses a binary search algorithm against a precision reference to determine the digital code for an analog input. In the system hierarchy, the MAX1240BEPA+ sits below instrumentation-class SAR ADCs and above 8-bit successive-approximation parts, with 12 bits representing a widely-used resolution for sensor readout, process control, and portable instrumentation where 8 bits is too coarse and 14/16 bits is unnecessary.
Key features include a 73 ksample/s sampling rate, 1 analog input channel, single-ended input range of 0V to Vref with Vref up to 3.6V, an internal track/hold, and a serial data output clocked by an external SCLK. The MAX1240 draws very low supply current during conversion and drops to microamp-level quiescent current in shutdown, which is enabled via a dedicated hardware pin. The 8-pin PDIP footprint allows easy breadboarding and through-hole prototyping.
The device is built on a BiCMOS process to combine low-noise analog input buffering with low-power CMOS digital logic. Because it uses an external reference (rather than the internal 2.5V reference of the MAX1240A/MAX1241A variants), designers can connect any precision low-drift reference - such as the MAX6126 - to optimize noise, scale the input range, or ratiometrically track a sensor bridge excitation voltage.
Typical applications include portable data logging, hand-held instrumentation, sensor signal conditioning (thermocouple, RTD, strain gauge), process control analog front-ends, battery-powered measurement equipment, and 4 mA to 20 mA loop-powered industrial sensors. The low power-down current makes it especially suitable for duty-cycled, battery-powered designs.
When designing with this part, choose a low-noise reference and place the input bypass capacitor close to AVDD. Ensure SCLK runs no faster than the datasheet-specified maximum and allow tCONV between CNVST rising edge and the first SCLK-driven bit clock-out. Refer to the manufacturer datasheet for full timing and absolute maximum ratings.
This page synthesizes distributor pricing, parametric drop-in alternatives, and practical design notes not found in the manufacturer datasheet - giving procurement and design engineers a single reference for evaluation, sourcing, and second-source decisions.
直接替換替代品，適用於 MAX1240BEPA+ — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： MAX1240BEPA+ （相同外形與佔位） — 差異在於 Conversion Time, Package, Input Type, Number of Channels, Operating Temperature Range.
MAX1240BCPA+
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
MAX1241BEPA+
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
MAX1240BEPA+
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →MAX1240BEPA
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
MAX1240EEPA+
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
MAX1240BEPA+ 最大額定值與電氣特性
| 解析度 | 12 bits |
| Architecture | SAR (Successive Approximation) |
| 取樣率 | 73 ksamples/sec |
| Number of Input Channels | 1 (single-ended) |
| Input Type | Single-ended, pseudo-differential (AIN vs. GND) |
| Analog Supply Voltage | +2.7 V to +3.6 V (single supply) |
| Digital Supply Voltage | +2.7 V to +3.6 V (single supply) |
| Reference Type | External (MAX1240; MAX1241 has internal 2.5 V) |
| Reference Input Range | 0 V to +3.6 V (VREF ≤ AVDD) |
| Analog Input Range | 0 V to VREF |
| Data Interface | SPI / QSPI / MICROWIRE-compatible serial |
| Track-and-Hold | Internal, 1:1 S/H:ADC ratio |
| Power-Down Current | 5 µW (power-down mode) |
| 工作溫度 | 0 °C to +70 °C (commercial, 'E' grade) |
| 封裝 | 8-pin PDIP (E suffix) |
| 安裝類型 | Through-Hole (DIP) |
| Process Technology | BiCMOS |
| RoHS 狀態 | Compliant |
MAX1240BEPA+ 腳位配置
| 腳位 1 | VDD — Positive supply voltage, +2.7V to +3.6V |
| 腳位 2 | AIN — Analog input, single-ended, 0V to VREF |
| 腳位 3 | GND — Ground, 0V return for both analog and digital supplies |
| 腳位 4 | SCLK — Serial clock input from SPI master |
| 腳位 5 | DOUT — Serial data output, MSB first |
| 腳位 6 | SSTRB — Serial strobe / active-low chip-select |
| 腳位 7 | VREF — External reference voltage input, 0V to +3.6V |
| 腳位 8 | CNVST — Conversion start, active-low; tie high for power-down |
典型應用
MAX1240BEPA+ 適用於 6 應用s: Portable Data Logger, Handheld Multimeter / DMM, Thermocouple / RTD Signal Conditioning Front-End, Process-Control Analog Front-End, Battery-Powered Measurement Instrument, Industrial Sensor Readout Module.
Portable Data Logger
The MAX1240BEPA+'s 73 ksps sampling rate and 5 µW power-down current make it an ideal ADC core for handheld battery-powered data loggers that sample slowly and spend most of their time asleep. Position the part between a precision low-drift reference (such as MAX6126) and a small microcontroller hosting an SPI master; duty-cycle conversions to extend battery life from days into weeks. Single-ended 0V-VREF input is well-matched to 0-3V sensor outputs without active signal conditioning.
推薦
Handheld Multimeter / DMM
In a handheld digital multimeter, the MAX1240BEPA+ digitizes voltage, current-derived voltage, and resistance measurements with 12-bit precision (1 mV count at 3.3V full scale, ideal for 2000-count or 4000-count DMM displays). The 8-PDIP package is breadboard-friendly and supports the through-hole PCB assembly typical of low-volume test instruments. Its SPI interface ties directly into common microcontroller GPIO without external logic.
推薦
Thermocouple / RTD Signal Conditioning Front-End
Pairing the MAX1240BEPA+ with a precision op-amp driven thermocouple or 4-wire RTD front-end yields a 12-bit temperature readout suitable for industrial process monitoring, HVAC controls, and laboratory instrumentation. Ratiometric measurement against a low-drift reference keeps the cold-junction compensation error inside a few LSB over the 0°C to +70°C commercial range. The shutdown pin enables millisecond-duration conversions only when needed, keeping quiescent draw at the microamp level.
推薦
Process-Control Analog Front-End
Within a 4-20 mA current loop receiver or a 0-10V process-control input module, the MAX1240BEPA+ provides 12-bit digital conversion of a single-ended analog signal that has been level-shifted and filtered to the 0V to 3.6V input range. The external-reference architecture supports ratiometric scaling, where the same reference that excites the sensor also biases the ADC, eliminating gain error caused by reference drift in temperature.
推薦
Battery-Powered Measurement Instrument
Field-deployable measurement devices - whether an environmental sensor, agricultural telemetry node, or portable gas analyzer - benefit from the MAX1240BEPA+'s 5 µW shutdown draw, which lets a host microcontroller wake once per minute, take a single conversion, and return to sleep without measurable battery impact. A single 3V CR2032 lithium cell can power the ADC and a low-energy MCU for years in typical duty cycles.
推薦
Industrial Sensor Readout Module
In an industrial sensor readout module - such as a load-cell digitizer, bridge-sensor interface, or strain-gauge signal chain - the MAX1240BEPA+ provides the ADC slice of a small, low-cost sensing node. The external reference allows direct ratiometric scaling of the bridge excitation voltage, so bridge sensitivity error cancels out. Combined with a low-noise op-amp gain stage, the full signal chain delivers 12-bit precision across the 0°C to +70°C commercial range.
推薦
推薦產品摘要
工程參考資料，適用於 MAX1240BEPA+ — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | MAX1240BCPA+ | MAX1241BEPA+ | MAX1240BEPA | MAX1240EEPA+ |
|---|---|---|---|---|---|
| Brand | Analog Devices (Maxim Integrated) | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 8-PDIP | 8-PDIP - same | 8-PDIP - same | 8-PDIP - same | 8-PDIP - same |
| Resolution | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits |
| Sampling Rate | 73 ksps | 73 ksps | 73 ksps | 73 ksps | 73 ksps |
| Supply Voltage | +2.7V to +3.6V | +2.7V to +3.6V | +2.7V to +5.25V (wider) | +2.7V to +3.6V | +2.7V to +3.6V |
| Reference Type | External | External | Internal 2.5V | External | External |
| Power-Down Current | 5 µW | 5 µW | 5 µW | 5 µW | 5 µW |
| Operating Temperature | 0°C to +70°C | 0°C to +70°C | 0°C to +70°C | 0°C to +70°C | 0°C to +70°C (extended screening) |
主要差異化特點
- External reference allows ratiometric sensor bridge measurement (對比MAX1241BEPA+)
- Lower supply voltage ceiling suits 3.3V digital systems (對比MAX1241BEPA+)
- Through-hole PDIP supports prototyping and legacy assembly (對比MAX1240BCSA+ (SOIC-8))
設計說明
Place a 0.1µF X7R ceramic bypass capacitor as close as possible to the VDD pin (pin 1) with a 1µF or larger bulk capacitor on the same node. Tie CNVST/active-low high between conversions to enter power-down mode (5 µW), reducing average supply current to microamp levels in duty-cycled designs. AVDD and DVDD should share a single well-decoupled supply rail.
Route the analog input trace (AIN, pin 2) directly to the source sensor with a guard trace tied to GND or with the surrounding copper plane grounded. Keep digital traces (SCLK, DOUT, SSTRB, CNVST) physically separated from the analog input trace to avoid digital noise coupling into the ADC input. Place the external reference (such as a MAX6126) close to the VREF pin (pin 7) and add a 0.1µF bypass on its output.
Do not apply VREF greater than AVDD or above +3.6V - this will damage or saturate the ADC's reference input. Ensure SCLK does not exceed the datasheet maximum frequency and respect tCONV timing between CNVST falling edge and the first SCLK rising edge that clocks data out. Single-ended input assumes the signal reference is at GND; using a pseudo-differential input requires tying the negative terminal to a quiet mid-rail such as VREF/2.
合規資訊
RoHS compliant per Maxim Integrated product page. Commercial 0°C to +70°C operating range - not AEC-Q100 qualified (industrial -40°C to +85°C variants are not available in this PDIP version; see MAX1240AESA+ in SOIC-8 for extended temperature).
