MAX1228ACEP+ - 12-Bit 300ksps 12-Ch ADC + Temp Sensor | Maxim
MPN： MAX1228ACEP+ ✓ 啟用中MAX1228ACEP+ 概覽
What is a SAR ADC? A successive-approximation-register analog-to-digital converter is a precision data-conversion topology that resolves a sample one bit at a time using an internal DAC and comparator, achieving 12-bit resolution in tens of microseconds without the latency or pipeline delay of a pipelined converter. SAR ADCs sit in the broader hierarchy of data converters (ADC), under mixed-signal ICs and integrated circuits, and are preferred for multiplexed precision sampling in industrial control and instrumentation where low latency and DC accuracy matter more than multi-MHz sampling rates.
Key features include 12-bit resolution with no missing codes, 300 ksps maximum throughput on a single channel, an analog multiplexer with 6 or 12 inputs that can be configured as single-ended or pseudo-differential channels, an internal 4.096 V reference with low drift, and a 16-entry FIFO that offloads the host controller by allowing burst conversions without per-sample interrupt overhead. The integrated temperature sensor with plus or minus 1 degree C accuracy eliminates an external thermistor for system thermal monitoring.
Architecture-wise, the MAX1228 uses a charge-redistribution DAC in the SAR loop, an input track-and-hold that accepts true-differential inputs common-mode up to the rails, an SPI/QSPI/MICROWIRE-compatible serial interface, and a sequencer that supports both scan mode (autonomous channel cycling) and single-channel conversions. AutoShutdown reduces supply current to a few microamps between conversions, making the part attractive for battery-backed data loggers.
Typical applications include process control and factory automation, multichannel data acquisition systems, patient monitoring and medical instrumentation, portable battery-powered data loggers, and system temperature monitoring with sensor compensation.
When designing with this ADC, place the 0.1 uF AVVDD bypass and the 10 uF reference bypass capacitor within 5 mm of their respective pins. For best noise performance, use a buffered external reference source if the internal 4.096 V ref accuracy is insufficient for the application - the reference pin can source up to 1 mA.
This page synthesizes distributor pricing, drop-in same-package alternatives, parametric comparisons, and practical design notes beyond the bare datasheet, including a same-package vs same-package trade-off matrix.
直接替換替代品，適用於 MAX1228ACEP+ — 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： MAX1228ACEP+ （相同外形與佔位） — 差異在於 Analog Supply Voltage, Architecture, Mounting Type, Resolution, Data Interface.
MAX1228BCEP+
✅ 直接替換📋 參考替代品（不在目錄中）
MAX1228AEEP+
✅ 直接替換聯絡詢價
查看資料表 →MAX1228ACEP+T
✅ 直接替換聯絡詢價
查看資料表 →MAX1229ACEP+
✅ 直接替換聯絡詢價
查看資料表 →MAX1227ACEP+
✅ 直接替換📋 參考替代品（不在目錄中）
MAX1230ACEP+
✅ 直接替換📋 參考替代品（不在目錄中）
MAX1228ACEP+ 最大額定值與電氣特性
| 解析度 | 12 bits |
| Sample Rate | 300 ksps |
| Input Channels | 6 or 12 (configurable) |
| Architecture | SAR (Successive Approximation) |
| Converter Count | 1 |
| Analog Supply Voltage | 4.75 V to 5.25 V |
| Digital Logic Supply | 4.75 V to 5.25 V |
| Internal Reference | 4.096 V |
| 內建溫度感測器 | Yes (+/-1 degree C accuracy) |
| On-Chip FIFO | 16 entries |
| AutoShutdown | Yes |
| Data Interface | SPI/QSPI/MICROWIRE-compatible serial |
| Analog Input Type | Single-ended / pseudo-differential |
| Package Type | 20-pin QSOP (SSOP, 0.154 in / 3.90 mm width) |
| 安裝類型 | Surface Mount (gull-wing leads) |
| Lead Finish / RoHS | Lead-free / RoHS compliant (per + suffix ordering code) |
| Input Multiplexer Topology | True analog MUX, sequential scanning supported |
MAX1228ACEP+ 腳位配置
| 腳位 1 | CS — Chip Select (active-low serial interface enable) |
| 腳位 2 | AIN0 — Analog Input 0 (multiplexer channel 0) |
| 腳位 3 | AIN1 — Analog Input 1 (multiplexer channel 1) |
| 腳位 4 | AIN2 — Analog Input 2 (multiplexer channel 2) |
| 腳位 5 | AIN3 — Analog Input 3 (multiplexer channel 3) |
| 腳位 6 | AIN4 — Analog Input 4 (multiplexer channel 4) |
| 腳位 7 | AIN5 — Analog Input 5 (multiplexer channel 5) |
| 腳位 8 | AIN6 — Analog Input 6 (multiplexer channel 6) |
| 腳位 9 | AIN7 — Analog Input 7 (multiplexer channel 7) |
| 腳位 10 | AIN8 — Analog Input 8 (multiplexer channel 8) |
| 腳位 11 | AIN9 — Analog Input 9 (multiplexer channel 9) |
| 腳位 12 | AIN10 — Analog Input 10 (multiplexer channel 10) |
| 腳位 13 | AIN11 — Analog Input 11 (multiplexer channel 11) |
| 腳位 14 | AVDD — Analog Supply Voltage (4.75 V to 5.25 V) |
| 腳位 15 | DVDD — Digital Supply Voltage (4.75 V to 5.25 V) |
| 腳位 16 | REF — Internal 4.096 V Reference (bypass with 10 uF cap) |
| 腳位 17 | GND — Ground |
| 腳位 18 | DRDY — Data Ready output (active-low conversion complete indicator) |
| 腳位 19 | DOUT — Serial Data Output (SPI MOSI from ADC) |
| 腳位 20 | SCLK — Serial Clock Input (SPI SCLK from host) |
典型應用
MAX1228ACEP+ 適用於 7 應用s: Multi-Channel Process Control Data Acquisition, Battery-Powered Remote Sensor Data Logger, Industrial Patient Monitoring Front-End, HVAC Building Automation Sensor Module, Rack-Level Server Power and Thermal Monitoring, Portable Test and Measurement Instrumentation, Automotive Aftermarket Telemetry and Diagnostics.
Multi-Channel Process Control Data Acquisition
The MAX1228ACEP+ fits process-control data acquisition cards that need to scan 6 to 12 sensor inputs (4-20 mA-derived, RTD, thermocouple-amplified) into a single ADC stream. The 300 ksps burst rate supports sequential scanning of all 12 channels at better than 25 ksps per channel, well above typical 1 to 10 ksps control-loop requirements. The internal 4.096 V reference gives a 1 mV-per-LSB conversion scale, while the FIFO holds 16 conversion results so the host controller can service the SPI bus only once per 16 samples, leaving CPU bandwidth for control-law execution.
推薦
Battery-Powered Remote Sensor Data Logger
The MAX1228ACEP+ suits remote, battery-powered data loggers where a handful of analog sensors (soil moisture, wind speed, pH, RTD temperature) are multiplexed into one ADC channel set. The AutoShutdown feature drops AVDD current to a few microamps between conversions, extending battery life on multi-year deployments. The internal temperature sensor logs the board's own temperature for sensor-compensation in post-processing, eliminating an external thermistor and saving power. The SPI interface is compatible with low-power microcontrollers like the MAX32625 family on the same I2V rail.
推薦
Industrial Patient Monitoring Front-End
The MAX1228ACEP+ is used in patient-monitoring front-end boards that multiplex ECG leads, SpO2 photodiode outputs, respiration-derived analog signals, and skin/skin-probe temperature into one SAR ADC. The 12-bit resolution at 1 mV-per-LSB is sufficient for SpO2 and ECG envelope detection, and the integrated temperature sensor acts as a board-level thermal monitor for the analog front-end. Its 300 ksps burst rate allows oversampling of two or three channels at the same time for higher effective resolution in the digital signal chain.
推薦
HVAC Building Automation Sensor Module
In HVAC building-automation sensor modules, the MAX1228ACEP+ takes input from thermistor bridges, CO2 sensor analog outputs, occupancy-sensor analog front-ends, and duct-pressure transducers. Its 12-channel multiplexer covers a typical 8 to 12 sensor count without an external mux IC. The on-chip FIFO buffers up to 16 results, so the module can sample in burst mode during a quiet building period and wake the host MCU only periodically, which reduces standby power.
推薦
Rack-Level Server Power and Thermal Monitoring
The MAX1228ACEP+ works in rack-level server and storage enclosure monitoring cards that read PSU voltage/current telemetry, fan tachometer-conditioned analog signals, and inlet/outlet temperature sensor arrays. The 6/12-channel analog multiplexer maps naturally to a 1U monitoring board with 6 to 12 sensor inputs. The integrated temperature sensor with +/-1 degree C accuracy provides a board-level reference probe to verify ambient-correction algorithms applied to inlet sensor strings. The 16-entry FIFO aligns with typical 16-frame telemetry packets sent over I2C/SPI back to the system BMC.
推薦
Portable Test and Measurement Instrumentation
The MAX1228ACEP+ serves portable handheld test and measurement instruments (multimeters, oscilloscope probe-front-ends, data acquisition probes) needing multiple input ranges without an analog-input mux IC. Its 300 ksps sampling rate supports 1 MHz bandwidth probes when paired with a 4x oversample-and-filter digital pipeline. The on-chip FIFO lets the embedded MCU process measurement bursts in batches, and the internal temperature sensor provides a reference on-probe thermal reading for cold-junction compensation of thermocouple-style probes.
推薦
Automotive Aftermarket Telemetry and Diagnostics
After the OEM tier, the MAX1228ACEP+ is suitable for automotive aftermarket telemetry units that tap into 0-5 V conditioned signals from OBD-II breakout boxes, MAP/MAF-conditioned sensor wires, and on-board tilt/vibration analog sensors. The integrated temperature sensor logs cabin-board temperature for sensor-compensation purposes. The 20-QSOP footprint is small enough to fit in a sealed OBD-II dongle enclosure; automotive-grade sourcing for some fleets would call out the broader MAX1228 family with reference to the temperature grade.
推薦
推薦產品摘要
工程參考資料，適用於 MAX1228ACEP+ — 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 | MAX1228BCEP+ | MAX1228AEEP+ | MAX1227ACEP+ | MAX1229ACEP+ | MAX1230ACEP+ |
|---|---|---|---|---|---|---|
| Brand | Analog Devices (Maxim Integrated) | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 20-QSOP | 20-QSOP (same) | 20-QSOP (same) | 20-QSOP (same) | 20-QSOP (same) | 20-QSOP (same) |
| Resolution | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits |
| Maximum Sample Rate | 300 ksps | 300 ksps | 300 ksps | 300 ksps | 300 ksps | 300 ksps |
| Input Channels | 12 (single-ended / 6 pseudo-diff) | 12 (single-ended) | 12 (single-ended) | 10 (single-ended) | 12 (single-ended) | 12 (single-ended) |
| Internal Reference | 4.096 V | 4.096 V | 4.096 V | 4.096 V | External reference required | 4.096 V |
| Internal Temperature Sensor | Yes (+/-1 degree C) | Yes | Yes | Yes | Yes | Yes |
| On-Chip FIFO | 16 entries | 16 | 16 | 16 | 16 | 16 |
| Temperature Grade | Commercial (0 to +70 C, A grade) | Extended (-40 to +85 C, B/E grade) | Extended (-40 to +85 C, E grade) | Commercial | Commercial | Commercial |
主要差異化特點
- Built-in temperature sensor with +/-1 degree C accuracy (對比Generic 12-bit multiplexed SAR ADC without internal temperature sensor)
- 16-entry on-chip FIFO (對比Generic 12-bit SAR ADCs without FIFO)
- AutoShutdown reduces AVDD current to microamps between conversions (對比Analog Devices AD7091R (which lacks shutdown current scaling))
設計說明
Power the MAX1228ACEP+ from a low-noise 5 V LDO (e.g. an ADP7104 or equivalent) rather than a switching regulator upstream. The internal 4.096 V reference and the SAR comparator's input stage reject high-frequency noise at AVDD; supply noise above 50 kHz can leak through PSRR and appear as spurious bit activity. Place a 0.1 uF X7R bypass capacitor within 5 mm of AVDD, and a 10 uF X5R or greater bulk capacitor within 10 mm of AVDD. DVDD may be tied to AVDD in single-rail designs or driven separately for noise isolation.
Route analog input traces as a star fan-out from each AIN pin to its source sensor, with a guard trace tied to GND on either side of each AIN trace to limit cross-channel coupling. Keep the REF pin's 10 uF bypass capacitor within 5 mm of the REF pin with a short, wide trace back to GND pin 17. Place the digital SPI lines (CS, SCLK, DOUT, DRDY) at least 3 mm away from any analog input trace, and cross them at a 90-degree angle if unavoidable. The QSOP package's exposed-area underside should receive a continuous ground copper pour for thermal stability and AC return paths.
Do not apply signals to AIN0 through AIN11 that exceed AVDD + 0.3 V or fall below GND - 0.3 V - overvoltage on analog inputs can permanently damage the input ESD structures. Do not transmit on the SPI bus while DRDY is high unless using programmed AUTO mode; a glitchy CS or SCLK line can spuriously wake the part from AutoShutdown and inflate AVDD current by a factor of 100. If you observe noisy LSBs in lower channels, check that the reference bypass capacitor is populated and properly polarized - a missing or undersized bulk on REF is the single most common cause of noisy readings on this family.
For best SINAD and SNR, drive each AIN line with a low-impedance source (preferably less than or equal to 1 kohm) and add a 100 pF to 1 nF RC buffer capacitor right at the ADC pin to absorb sampling-charge transients. If the source is high-impedance (e.g. a resistive sensor divider), add an op-amp buffer (such as the MAX44246) between the sensor and the AIN pin. Pull CS high between conversion bursts to engage AutoShutdown and reduce quiescent supply current to a few microamps; leave CS tied low only during active bursts.
合規資訊
Lead-free and RoHS compliant per the + ordering code suffix in the MPN. AEC-Q100 automotive qualification is not typically advertised for this commercial-grade Maxim/Analog Devices ADC; extended-temperature grades (B/E) exist for industrial deployments.
