MAX1291BCEI - 12-Bit 250ksps 8-Ch SAR ADC +2.5V Ref | Maxim
MPN： MAX1291BCEI ✓ 啟用中MAX1291BCEI 概覽
A successive-approximation register (SAR) ADC is a type of Nyquist-rate converter that performs one conversion per clock cycle by stepping an internal DAC against the input signal and recording the code that brackets the input. SAR ADCs are prized for their deterministic latency, lack of pipeline delay, and excellent DC linearity, making them ideal for multiplexed multi-channel systems, instrumentation, and process control where multiple sensors must be digitized with a single converter.
Key features of the MAX1291BCEI include 250 ksps throughput, eight single-ended or four differential analog inputs, software-configurable unipolar/bipolar input ranges (0 to VREF or ±VREF), an internal +2.5 V bandgap reference, hardware-/software-configurable power-down modes, and a 12-bit wide parallel interface for direct connection to microcontrollers, DSPs, or FPGAs. The internal reference eliminates an external component and reduces BOM cost, while the 28-QSOP package saves PCB area versus larger SSOP alternatives.
At the architectural level, the part uses a charge-redistribution SAR core with an input track-and-hold, an internal +2.5 V reference (also accessible externally), and an eight-input analog multiplexer. Software-configurable input ranges (0 to VREF, 0 to 2 VREF, ±VREF, ±2 VREF) let the user match full-scale range to the sensor output without external signal conditioning. Power-down modes between conversions reduce average supply current to microamp levels, which is essential for battery-powered multi-channel scanners.
Typical applications include portable data loggers, multichannel sensor interfaces, industrial process control, patient monitoring front-ends, and bench-top instrumentation. When migrating to the +5 V family, designers can substitute the pin-compatible MAX1290/MAX1292, while the 4-channel pin-compatible variant is the MAX1293 in a smaller 24-QSOP package. For hardware design, ensure the analog supply is well bypassed with a 10 µF tantalum in parallel with a 0.1 µF ceramic near AVDD, and route digital and analog grounds using a star-ground or split-plane topology to avoid digital noise coupling into the analog input path.
直接替換替代品，適用於 MAX1291BCEI — 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： MAX1291BCEI （相同外形與佔位） — 差異在於 Input Type, RoHS Status, Sampling Rate, ADC Architecture, Analog Supply Voltage.
MAX1291BCEI+
✅ 直接替換📋 參考替代品（不在目錄中）
MAX1291BCEI+T
✅ 直接替換📋 參考替代品（不在目錄中）
MAX1291BEEI+
✅ 直接替換📋 參考替代品（不在目錄中）
MAX1291BEEI
✅ 直接替換聯絡詢價
查看資料表 →MAX1290ACEI
✅ 直接替換聯絡詢價
查看資料表 →MAX1292ACEI
✅ 直接替換📋 參考替代品（不在目錄中）
MAX1291BCEI 最大額定值與電氣特性
| 解析度 | 12 bit |
| Number of Channels | 8 single-ended / 4 differential (software-configurable) |
| 取樣率 | 250 ksps |
| ADC Architecture | SAR (Successive Approximation Register) |
| Supply Voltage (Analog) | 2.7 V to 3.6 V (single +3 V supply) |
| Supply Voltage (Digital) | 2.7 V to 3.6 V |
| Internal Reference Voltage | +2.5 V |
| 輸入電壓範圍 | 0 to VREF / 0 to 2 VREF / ±VREF / ±2 VREF (software-configurable) |
| Data Interface | Parallel (12-bit wide) |
| Number of Inputs | 4 or 8 (software-configurable) |
| Input Type | Single-Ended / Pseudo-Differential |
| 封裝 | 28-pin QSOP |
| 安裝類型 | Surface Mount |
| 工作溫度 | 0C to +70C (commercial grade, B suffix) |
| RoHS 狀態 | Compliant (BCEI suffix) |
| Power-Down Mode | Yes (hardware and software configurable) |
MAX1291BCEI 腳位配置
| 腳位 1 | AIN0 — Analog input channel 0 |
| 腳位 2 | AIN1 — Analog input channel 1 |
| 腳位 3 | AIN2 — Analog input channel 2 |
| 腳位 4 | AIN3 — Analog input channel 3 |
| 腳位 5 | AIN4 — Analog input channel 4 |
| 腳位 6 | AIN5 — Analog input channel 5 |
| 腳位 7 | AIN6 — Analog input channel 6 |
| 腳位 8 | AIN7 — Analog input channel 7 |
| 腳位 9 | AGND — Analog ground |
| 腳位 10 | REF — Reference I/O (internal +2.5V or external drive) |
| 腳位 11 | AVDD — Analog supply (+3V) |
| 腳位 12 | DVDD — Digital supply (+3V) |
| 腳位 13 | DGND — Digital ground |
| 腳位 14 | CS — Chip select (active low) |
| 腳位 15 | RD — Read strobe (active low) |
| 腳位 16 | WR — Write strobe / mode setup |
| 腳位 17 | CONVST — Conversion start |
| 腳位 18 | INT — Interrupt / end-of-conversion |
| 腳位 19 | D11/MSB — Data bit 11 (MSB) |
| 腳位 20 | D10 — Data bit 10 |
| 腳位 21 | D9 — Data bit 9 |
| 腳位 22 | D8 — Data bit 8 |
| 腳位 23 | D7 — Data bit 7 |
| 腳位 24 | D6 — Data bit 6 |
| 腳位 25 | D5 — Data bit 5 |
| 腳位 26 | D4 — Data bit 4 |
| 腳位 27 | D3/D2/D1/D0 — Lower data bits (multiplexed or shared with mode pins) |
| 腳位 28 | PD/PWRDN — Power-down control |
典型應用
MAX1291BCEI 適用於 6 應用s: Multichannel Sensor Data Acquisition, Portable Battery-Powered Data Logger, Industrial Process Control Front-End, Medical Patient Monitoring Front-End, Bench-Top Test & Measurement Instrument, Automotive Sensor Interface (Non-Safety).
Multichannel Sensor Data Acquisition
The MAX1291BCEI's 8 single-ended / 4 differential input channels and 250 ksps throughput make it a strong fit for multichannel sensor DAQ front-ends. Designers can digitize thermocouples, RTDs, strain gauges, or 4-20 mA loop outputs directly with the internal +2.5 V reference, eliminating an external reference and reducing BOM cost. Compared to slower ADCs (e.g. 100 ksps parts) the MAX1291 doubles per-channel settling margin when scanning eight channels at 10 kHz each, leaving headroom for channel-to-channel settling time. Place a unity-gain buffer (e.g. MAX4475) in front of each MUX input to drive the SAR's sampling capacitor without distortion, and use software-configurable input ranges to match transducer output spans without external signal conditioning.
推薦
Portable Battery-Powered Data Logger
For handheld or USB-powered loggers, the MAX1291BCEI's hardware- and software-configurable power-down modes reduce average supply current to microamp levels between conversions, extending battery life. The 28-QSOP package occupies only ~62 mm² of PCB area, leaving more room for memory and wireless modules. Combined with a low-power MCU (e.g. MAXQ610 or an ARM Cortex-M0+), the part forms a multi-channel logger that can digitize 8 sensors at 1 kHz each while drawing under 5 mW active. Use the internal +2.5 V reference to power ratiometric sensors (strain gauges, thermistors) so absolute accuracy tracks the supply instead of an external reference drift.
推薦
Industrial Process Control Front-End
In PLCs, distributed I/O modules, and process-control instrumentation the MAX1291BCEI provides 8 channels of 12-bit digitization with software-selectable input ranges (±5 V, 0-10 V, 0-5 V, ±2.5 V), eliminating external range-switching relays or instrumentation amps. The 250 ksps throughput handles per-channel update rates up to 31 kHz in 8-channel round-robin mode. The MAX1291BEEI+ industrial-grade variant extends operation to -40C to +85C for outdoor cabinets. Galvanic isolation between the ADC and the host MCU is recommended using digital isolators (e.g. MAX14850) to break ground loops in long-cable installations.
推薦
Medical Patient Monitoring Front-End
Patient monitors require multi-lead ECG, SpO2, temperature, and respiration channels that must be digitized at low power and with deterministic latency. The MAX1291BCEI's SAR architecture delivers no pipeline delay, so each conversion result is available immediately - critical for real-time QRS detection and arrhythmia algorithms. The internal +2.5 V reference biases ratiometric bridges (e.g. SpO2 photodiode transimpedance amps) directly. With 250 ksps aggregate throughput the part can digitize 8 leads at >30 kHz per channel, well above the Nyquist rate for ECG bandwidth. For FDA/IEC 60601-1 compliant designs add isolation and verify EMC per the standard - the SAR core itself does not introduce EMI of concern.
推薦
Bench-Top Test & Measurement Instrument
Digital multimeters, source-measure units, and bench-top oscilloscope auxiliary digitizers benefit from the MAX1291BCEI's combination of 8 channels, 12-bit resolution, and parallel interface. The parallel data bus connects directly to FPGAs or DSPs used for signal processing and display, with deterministic conversion timing simplifying calibration routines. Using the internal +2.5 V reference plus software-configurable bipolar input ranges (±2.5 V, ±5 V) allows direct measurement of common sensor outputs without external scaling. For higher-accuracy DMMs, an external reference (MAX6126) can replace the internal reference to drop full-scale TC below 5 ppm/C.
推薦
Automotive Sensor Interface (Non-Safety)
Non-safety automotive subsystems - body controllers, HVAC modules, battery management telemetry, and infotainment auxiliaries - often use the MAX1291BCEI for digitizing temperature, pressure, and position sensors. For underhood or engine-bay applications where ambient temperatures exceed 70C, the industrial MAX1291BEEI+ variant is recommended (AEC-Q100 is NOT qualified for either variant - select a different part for safety-critical ADAS use). The 28-QSOP package and 8 channels in a single IC reduce board area versus discrete ADC + MUX solutions, simplifying ECU layout and BOM.
推薦
推薦產品摘要
工程參考資料，適用於 MAX1291BCEI — 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 | MAX1291BCEI+ | MAX1291BCEI+T | MAX1291BEEI+ | MAX1291BEEI | MAX1290ACEI | MAX1292ACEI |
|---|---|---|---|---|---|---|---|
| Brand | Maxim Integrated (Analog Devices) | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 28-QSOP | 28-QSOP - same | 28-QSOP - same | 28-QSOP - same | 28-QSOP - same | 28-QSOP - same | 28-QSOP - same |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit |
| Sampling Rate | 250 ksps | 250 ksps | 250 ksps | 250 ksps | 250 ksps | 250 ksps | 250 ksps |
| Input Channels | 8 SE / 4 DI | 8 SE / 4 DI | 8 SE / 4 DI | 8 SE / 4 DI | 8 SE / 4 DI | 8 SE / 4 DI | 8 SE / 4 DI |
| Supply Voltage | 2.7 V to 3.6 V (+3 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 3.6 V | 4.75 V to 5.25 V (+5 V) | 4.75 V to 5.25 V (+5 V) |
| Internal Reference | +2.5 V | +2.5 V | +2.5 V | +2.5 V | +2.5 V | +2.5 V | +2.5 V |
| Operating Temperature | 0C to +70C | 0C to +70C | 0C to +70C | -40C to +85C | -40C to +85C | 0C to +70C | 0C to +70C |
| Data Interface | Parallel (12-bit) | Parallel (12-bit) | Parallel (12-bit) | Parallel (12-bit) | Parallel (12-bit) | Parallel (12-bit) | Parallel (12-bit) |
主要差異化特點
- Internal +2.5 V reference eliminates external reference component (對比MAX1291BCEI+)
- Software-configurable unipolar/bipolar input ranges up to ±5 V (對比MAX1291BCEI+T)
- True pin-compatibility with the +5 V MAX1290/MAX1292 family (對比MAX1290ACEI)
- Hardware- and software-configurable power-down reduces Iq to microamps (對比MAX1293BCEI)
設計說明
Bypass AVDD and DVDD independently with a 10 uF tantalum in parallel with a 0.1 uF ceramic placed within 5 mm of each supply pin. The MAX1291BCEI draws both analog and digital current from the same +3 V rail; a ferrite bead or small series resistor between AVDD and DVDD can prevent digital switching noise from corrupting the analog reference. Use a star-ground topology to keep the ADC's AGND return separate from high-current digital returns.
Do not drive the analog inputs beyond AVDD + 0.3 V or below AGND - 0.3 V; out-of-range inputs will forward-bias the input ESD diodes and inject charge into the sampling capacitor, causing large conversion errors. Always include series input resistors (1 kOhm typical) if the source can exceed the supply rail during fault conditions, and add external clamping diodes for over-voltage protection on industrial inputs.
Route the parallel data bus (D0-D11) away from the analog input traces and the REF pin; keep digital outputs on the opposite side of the package from AIN0-AIN7. Provide a solid analog ground plane under the ADC and connect AGND and DGND at a single point near the IC. If using the internal +2.5 V reference to bias external circuitry, buffer the REF pin with a low-noise op-amp (e.g. MAX4475) to prevent load transients from modulating the reference voltage.
The SAR core draws a transient current spike from REF during each conversion bit decision. Add a 10 uF (or larger) decoupling capacitor directly at the REF pin to prevent reference droop, which would otherwise manifest as code-dependent gain error. For multi-MHz switching frequencies the REF bypass should be ceramic (low ESR), not electrolytic, to handle the fast edges.
合規資訊
RoHS compliant per Maxim/Analog Devices BCEI/+ product marking. AEC-Q100 NOT qualified - do not use in automotive safety-critical applications. Lead-free finish (BCEI+) confirmed in distributor listings.
