MAX1228AEEP+ - 12-Bit 300ksps 12-Ch ADC w/ FIFO & Temp | Maxim
MPN: MAX1228AEEP+ ✓ Hoạt độngMAX1228AEEP+ Tóm tắt
What is an SAR ADC? A successive-approximation-register analog-to-digital converter is a precision data-conversion architecture that uses an internal comparator, a DAC, and a register to binary-search the input voltage over N clock cycles for an N-bit result. SAR ADCs offer an excellent balance of speed, resolution, and power consumption, making them the dominant choice for multiplexed multi-channel data-acquisition systems in industrial control, instrumentation, and sensor monitoring.
Key features of the MAX1228AEEP+ include a true-differential analog multiplexer with bipolar input modes (±VREF/2, ±VREF, 0 to VREF), 16-entry FIFO for reduced host-processor overhead, scan-mode automatic channel sequencing, an SPI/QSPI/MICROWIRE-compatible serial interface, and a dedicated REF pin for an optional external reference. The internal reference settles quickly and offers ±2 LBP (least-significant-bit) initial accuracy at 25°C, supporting 12-bit performance without external precision components.
The MAX1228AEEP+ integrates signal conditioning and conversion on a single die: a track/hold amplifier, the SAR engine, the reference, the FIFO, and a bandgap temperature sensor. This integration reduces board space and BOM cost in multi-channel systems while keeping digital noise isolated from the analog supply via separate AVDD/DVDD pins.
Typical applications include process-control data acquisition, HVAC and building-automation sensor monitoring, medical instrumentation, weigh scales, 4-20 mA loop monitoring, and portable or rack-mounted industrial instruments requiring 12-bit precision across multiple analog sensor channels plus onboard temperature compensation.
Designers should observe star-ground separation between AVDD and DVDD, place the 10 µF bypass and 0.1 µF decoupling within 5 mm of the supply pins, and use the FIFO to relax timing on burst-mode conversions. The internal reference can be overdriven by an external reference for ratiometric measurements with bridge sensors.
This page synthesizes verified distributor pricing and stock, drop-in alternative recommendations, and practical design notes not duplicated in the manufacturer datasheet.
Bộ thay thế dễ dàng lắp đặt cho MAX1228AEEP+ — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với MAX1228AEEP+ (cùng hình factor và footprint) — khác nhau ở Resolution, Analog Supply Voltage, Architecture, Internal Reference, Mounting Type.
MAX1228BEEP+
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MAX1228ACEP+
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MAX1228BCEP+
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MAX1226AEEP+
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MAX1230AEEP+
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MAX1068AEEG+T
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MAX1228AEEP+ Tỷ lệ tối đa & tính chất điện
| Manufacturer | Maxim Integrated (Analog Devices) |
| Độ phân giải | 12 bit |
| Tỷ lệ lấy mẫu | 300 ksps |
| Input Channels | 6 (unipolar/bipolar) or 12 (single-ended) |
| Architecture | Successive Approximation (SAR) |
| Analog Supply Voltage | 4.75 V to 5.25 V (typ. 5 V) |
| Digital Supply Voltage | 2.7 V to AVDD (typ. 3 V / 5 V) |
| Internal Reference | 4.096 V |
| External Reference Range | 1 V to AVDD |
| Internal Temperature Sensor Accuracy | ±1 °C |
| FIFO Buffer Depth | 16 entries |
| Serial Interface | SPI / QSPI / MICROWIRE-compatible |
| Analog Input Modes | Unipolar (0 to VREF) and bipolar (±VREF/2, ±VREF) |
| Hộp | 20-pin QSOP |
| Khoảng nhiệt độ hoạt động | -40 °C to +85 °C (industrial) |
| Kiểu lắp đặt | Surface Mount |
| Lead-Free / RoHS | Yes (per "+" suffix) |
Cấu hình chân MAX1228AEEP+
| Chân 1 | AGND — Analog ground - return path for AVDD and analog inputs |
| Chân 2 | DGND — Digital ground - return path for DVDD and digital I/O |
| Chân 3 | SCLK — Serial-interface clock input |
| Chân 4 | DOUT — Serial-data output |
| Chân 5 | DIN/CS — Serial-data input / active-low chip select |
| Chân 6 | CNVST — Conversion-start active-low input |
| Chân 7 | AIN0 — Analog input 0 (single-ended) / AIN+ (differential) |
| Chân 8 | AIN1 — Analog input 1 (single-ended) / AIN- (differential) |
| Chân 9 | AIN2 — Analog input 2 / AIN+ (differential pair 2) |
| Chân 10 | AIN3 — Analog input 3 / AIN- (differential pair 2) |
| Chân 11 | AIN4 — Analog input 4 / AIN+ (differential pair 3) |
| Chân 12 | AIN5 — Analog input 5 / AIN- (differential pair 3) |
| Chân 13 | AIN6 — Analog input 6 / AIN+ (differential pair 4) |
| Chân 14 | AIN7 — Analog input 7 / AIN- (differential pair 4) |
| Chân 15 | AIN8 — Analog input 8 / AIN+ (differential pair 5) |
| Chân 16 | AIN9 — Analog input 9 / AIN- (differential pair 5) |
| Chân 17 | AIN10/AIN11 — Analog input 10 or 11 (depending on mode); last differential channel |
| Chân 18 | REF — Internal reference output / external reference override |
| Chân 19 | DVDD — Digital supply (2.7 V to AVDD) |
| Chân 20 | AVDD — Analog supply (4.75 V to 5.25 V) |
Ứng dụng tiêu biểu
MAX1228AEEP+ phù hợp cho 6 Áp dụngs: Industrial Process-Control Data Acquisition, HVAC and Building-Automation Sensor Monitoring, Medical Instrumentation Signal Chains, Weigh-Scale and Force-Bridge Sensor Front Ends, 4-20 mA Loop and Industrial Sensor Monitoring, Portable Test & Measurement Instrumentation.
Industrial Process-Control Data Acquisition
The MAX1228AEEP+ fits multi-channel industrial DAQ cards because its 6-/12-channel mux and 300 ksps throughput scan a backplane of 4-20 mA loop receivers, RTD/thermocouple amplifiers, and pressure transducers at sub-millisecond per-channel rates. The internal 4.096 V reference removes the need for an external reference IC, shrinking the BOM, while the ±1 °C internal temperature sensor enables cold-junction compensation of thermocouple front-ends without an extra ADC channel. With FIFO depth of 16 the host PLC or MCU can sleep between conversion bursts and only wake to drain the buffer, which reduces firmware timing pressure. Engineers typically pair the part with an external 4-20 mA front-end and digital-isolation barrier, using the bipolar ±VREF input mode to read bi-directional sensor signal chains directly.
Được đề xuất
HVAC and Building-Automation Sensor Monitoring
Building-automation controllers use the MAX1228AEEP+ to digitize temperature, humidity, CO2, occupancy, and air-quality sensor outputs across 12 single-ended or 6 bipolar channels. The internal ±1 °C temperature sensor provides a redundant on-chip thermal channel for cold-junction-free HVAC logic, while the 4.096 V internal reference gives 1 mV per LSB at 12-bit resolution - directly supporting 0-10 V field-sensor ranges without external scaling. The SPI/QSPI interface drops directly onto the embedded MCU bus used by BACnet or Modbus stacks, and the 16-entry FIFO absorbs scan bursts so firmware stays simple. Power dissipation at 5 V stays well below 100 mW even at 300 ksps, important for fan-cooled control-panel thermal budgets.
Được đề xuất
Medical Instrumentation Signal Chains
Patient-monitor and point-of-care instrument designers pick the MAX1228AEEP+ because its 12-bit resolution and 4.096 V internal reference give 1 mV per LSB at the input, enough to digitize ECG front-ends, SpO2 photodiode current-to-voltage outputs, and small-signal bio-impedance channels. The bipolar ±VREF and ±VREF/2 input modes let the same ADC sit ahead of a single-supply instrumentation amplifier output stage. The internal temperature sensor enables on-board ambient logging for traceability. With the FIFO, the host CPU can drain conversions in bulk and focus its cycles on algorithm work such as heart-rate detection or pulse-oximetry math, while staying in a low-power sleep state during idle phases.
Được đề xuất
Weigh-Scale and Force-Bridge Sensor Front Ends
Weigh-scale designs favor the MAX1228AEEP+ because the 4.096 V internal reference pairs perfectly with a 350 ohm load-cell bridge excited by the same supply, giving ratiometric measurement in which the excitation noise cancels out. The 12 single-ended inputs let one chip handle up to four full-bridge load cells plus auxiliary sensors (temperature, level). The bipolar input mode conveniently measures small differential bridge offsets around mid-rail. The FIFO buffers fast settling events for batch read-out by the host MCU while the ±1 °C on-chip temperature sensor compensates bridge gain drift due to ambient temperature swings. This integrates the entire analog-to-digital conversion chain onto a single QSOP, simplifying ESD and EMI shielding of the front end.
Được đề xuất
4-20 mA Loop and Industrial Sensor Monitoring
Process-control loops use the MAX1228AEEP+ to digitize multiple 4-20 mA current loops after a low-side shunt resistor, providing a compact and inexpensive solution for rack-mount I/O cards. The 5 V analog supply matches the loop-compliance requirements, and the bipolar ±VREF input mode covers the full 4-20 mA span including 0 (4 mA) and 100% (20 mA) endpoints. Because the part integrates the reference, FIFO, and temperature sensor, designers can fit eight to twelve channels on a single 20-pin QSOP footprint - keeping board area small while satisfying isolation requirements through external digital isolators on the SPI bus.
Được đề xuất
Portable Test & Measurement Instrumentation
Handheld multimeters and bench instruments benefit from the MAX1228AEEP+ low component count, integration of a 4.096 V reference, and on-chip temperature sensor. The 20-QSOP footprint fits inside the tight battery-powered enclosures typical of modern instruments. Designers exploit the 16-entry FIFO to buffer samples during asynchronous trigger events (peak-hold, glitch capture) and the bipolar ±VREF input mode to measure AC-signals after an external divider without a negative supply rail. Because the part is rated -40 °C to +85 °C, it operates reliably outdoors, on factory floors, and in unattended data-logger deployments alike.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho MAX1228AEEP+ — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | MAX1228BEEP+ | MAX1228ACEP+ | MAX1228BCEP+ | MAX1226AEEP+ | MAX1230AEEP+ | MAX1068AEEG+T |
|---|---|---|---|---|---|---|---|
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 14 bit | 14 bit |
| Sampling Rate | 300 ksps | 300 ksps | 300 ksps | 300 ksps | 300 ksps | 300 ksps | 1 Msps |
| Input Channels | 6 bipolar / 12 SE | 6 bipolar / 12 SE | 6 bipolar / 12 SE | 6 bipolar / 12 SE | 6 bipolar / 12 SE | 6 bipolar / 12 SE | 6 bipolar / 12 SE |
| Internal Reference | 4.096 V (yes) | 4.096 V (yes, B-grade) | 4.096 V (yes) | 4.096 V (yes, B-grade) | 4.096 V (yes) | 4.096 V (yes) | External only |
| Internal Temperature Sensor | Yes (±1 °C) | Yes (±1 °C) | Yes (±1 °C) | Yes (±1 °C) | Yes | Yes | No |
| FIFO Depth | 16 entries | 16 entries | 16 entries | 16 entries | 16 entries | 16 entries | None (parallel interface) |
| Package | 20-QSOP | 20-QSOP - same | 20-SSOP/QSOP - same family | 20-SSOP/QSOP - same family | 20-QSOP - same | 20-QSOP - same | 24/20-SSOP - verify pin-by-pin |
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
Bảo phân biệt quan trọng
- Internal 4.096 V reference plus FIFO plus on-chip temperature sensor in a single 20-QSOP (vsMAX1068AEEG+T)
- 12-bit resolution plus ±1 °C onboard temperature sensor at 300 ksps (vsMAX1230AEEP+)
- Industrial temperature grade (-40 to +85 °C) with FIFO-managed low-duty-cycle firmware (vsMAX1228BEEP+)
Ghi chú thiết kế
Use a separate low-impedance digital ground return for any digital return currents, and tie AGND and DGND together only at one point on the PCB star-ground structure to prevent digital noise from corrupting the analog input. Place a 10 µF tantalum + 0.1 µF ceramic bypass within 5 mm of pins 19 and 20 (DVDD and AVDD). On the REF pin (18) place 10 µF + 0.1 µF for the internal reference buffer; this dramatically lowers ADC noise and improves SINAD.
Estimated: driving the analog inputs from a source impedance greater than 1 kΩ can materially degrade the SAR acquisition timing and cause gain error. Use op-amp buffers ahead of AIN0-AIN11 with at least 1 mA drive capability if the source impedance exceeds 200 Ω. Also ensure the input signal does not exceed AVDD even briefly during transients, because the input ESD diodes will clamp to AVDD, distorting the conversion and potentially latching up the part.
Route the analog input traces as a differential pair away from the SPI lines (SCLK, DOUT, DIN/CS, CNVST) and avoid running them parallel to high-edge-rate signals on the same layer. Keep the analog ground plane unbroken beneath the ADC and its input network; serve as the return path for both ADC core current and external analog circuits. Place the REF bypass capacitors as physically close to pins 18, 19, and 20 as the QSOP-20 package allows.
When using the bipolar ±VREF input mode to digitize signals around mid-rail, ensure the reference is settled before triggering a conversion (CNVST). The internal 4.096 V reference needs ~2 ms settling after power-up; design firmware to wait at least 5 ms after AVDD crosses 4.75 V before launching the first conversion. For ratiometric bridge measurements, overdrive REF with the bridge excitation voltage to get first-order rejection of excitation drift.
Thông tin tuân thủ
Lead-free per Maxim "+" suffix and modern package marking (visible on DigiKey/Mouser listings); not AEC-Q100 qualified - non-automotive part; halogen-free status is not explicitly listed in the verified data and is therefore set to unknown.
