MAX157AEPA - 108ksps 10-Bit 2-Ch Serial ADC | Maxim Integrated
MPN: MAX157AEPA ✓ Hoạt độngMAX157AEPA Tóm tắt
An ADC (Analog-to-Digital Converter) is a mixed-signal integrated circuit that converts a continuous analog input voltage into a discrete digital code word. SAR ADCs use a binary-search algorithm implemented with a capacitive DAC and comparator to digitize each sample in N clock cycles for N-bit resolution, providing an excellent trade-off between speed, accuracy, and power. The MAX157AEPA belongs to the SAR ADC sub-family within the broader data-converter hierarchy (ADC -> data converter -> mixed-signal IC -> semiconductor). The MAX157/MAX159 family specifically targets low-power, multi-channel, serial-output applications where PCB area and quiescent current are at a premium.
Key specifications include a single +2.7V to +5.25V analog supply range, two true-differential or single-ended input channels (the MAX159 variant is single-channel true-differential; the MAX157 offers two single-ended channels), an integrated +4.096V or external reference option, an INL of plus or minus 0.5 LSB, a DNL of plus or minus 1 LSB, an operating current of approximately 1.2 mA at full speed, an automatic power-down current of typically under 1 microamp between conversions, and an industrial operating temperature range of -40C to +85C. The serial interface runs at clock rates up to approximately 2.5 MHz to support the 108 ksps throughput, and the part accepts either an internal 2.5V reference or an external reference up to VDD.
Architecturally, the MAX157AEPA uses a charge-redistribution SAR ADC with input track-and-hold, an on-chip clock, and a digital serial engine that streams out MSB-first data. The internal reference and reference-buffer architecture provide low drift across temperature while keeping the external component count to a single bypass capacitor. Hardware shutdown control through the active-low SHDN pin combined with automatic wake-up between conversions makes the part well-suited to battery-powered data logging, portable instrumentation, and loop-powered sensor transmitters where average current dominates battery life.
Typical applications include portable battery-powered data acquisition, pen-digitizers and touch-screen controllers, portable medical instruments, isolated industrial sensor front-ends, loop-powered 4-20 mA transmitters, and instrumentation clusters. The wide supply range and low quiescent current also suit automotive body controllers and HVAC sensor interfaces where the part operates directly from a regulated 5V or 3.3V rail.
When designing with the MAX157AEPA, place the 10 microfarad and 0.1 microfarad supply-bypass capacitors as close as possible to the AVDD and DVDD pins and route the analog and digital grounds to a single star-ground point to avoid digital switching noise coupling into the analog input. For best noise performance, configure the input in single-ended unipolar mode and use the on-chip 2.5V reference rather than an external rail-divider.
This page synthesizes distributor pricing, drop-in same-package and same-brand alternatives, and practical PCB layout notes not found in a single distributor product page.
Bộ thay thế dễ dàng lắp đặt cho MAX157AEPA — 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 MAX157AEPA (cùng hình factor và footprint) — khác nhau ở Architecture, Conversion Time, Operating Temperature, Package, RoHS Status.
MAX157AEPA+
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MAX157BEPA
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MAX157BCPA
✅ Drop-In ⚠️ Thông số chưa được xác minhLiên hệ để biết giá
Xem tài liệu →MAX159AEPA
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MAX147AEAP
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MAX157AEPA Tỷ lệ tối đa & tính chất điện
| Độ phân giải | 10 bit |
| Number of Channels | 2 |
| Tỷ lệ lấy mẫu | 108 ksps |
| Conversion Time | 7.4 us |
| Điện áp cung cấp | +2.7 V to +5.25 V (single) |
| Supply Current (active) | 1.2 mA (typ) |
| Supply Current (power-down) | < 1 uA (typ) |
| Input Configuration | 2 single-ended (MAX157) / 1 differential (MAX159) |
| Giao diện | SPI/QSPI/MICROWIRE-compatible serial |
| INL | +/- 0.5 LSB (max) |
| DNL | +/- 1 LSB (max) |
| Reference | Internal 2.5 V or external up to VDD |
| Nhiệt độ hoạt động | -40 C to +85 C (industrial) |
| Hộp | PDIP-8 (through-hole, 0.300 in) |
| Architecture | SAR (successive-approximation register) |
| Shutdown Pin | Yes (active-low SHDN) |
| Kiểu lắp đặt | Through-Hole |
| Trạng thái RoHS | Compliant (MAX157AEPA+ variant) |
Cấu hình chân MAX157AEPA
| Chân 1 | VDD — Analog and digital supply, +2.7 V to +5.25 V |
| Chân 2 | AIN1 — Analog input channel 1 (single-ended) |
| Chân 3 | AIN0 — Analog input channel 0 (single-ended) |
| Chân 4 | REF — Reference input/output (internal 2.5 V or external) |
| Chân 5 | GND — Ground (analog and digital star-ground) |
| Chân 6 | DOUT — Serial data output, MSB first |
| Chân 7 | SCLK — Serial clock input |
| Chân 8 | CS — Active-low chip select / shutdown |
Ứng dụng tiêu biểu
MAX157AEPA phù hợp cho 6 Áp dụngs: Portable Battery-Powered Data Acquisition, Loop-Powered 4-20 mA Industrial Transmitter, Pen-Digitizer and Touch-Screen Controller, Portable Medical Instrumentation, Isolated Industrial Sensor Front-End, HVAC and Building Automation Sensors.
Portable Battery-Powered Data Acquisition
The MAX157AEPA's 1.2 mA active current plus sub-1 uA automatic power-down between conversions makes it ideal for portable battery-powered data acquisition. Operating from a single 3 V lithium cell, the ADC can digitize two sensor channels at 108 ksps and stream results over SPI to a low-power MCU. Placed between a resistive bridge sensor and the microcontroller, the SAR core adds only 7.4 microseconds of conversion latency while quiescent current between samples is negligible, extending battery runtime by 10x to 100x versus always-on ADCs. Designers should pair the MAX157AEPA with the on-chip 2.5 V reference and route the analog/digital grounds to a star point to keep noise below 0.5 LSB.
Được đề xuất
Loop-Powered 4-20 mA Industrial Transmitter
In a 4-20 mA loop-powered transmitter, the MAX157AEPA provides two single-ended input channels for bridge or RTD sensor conditioning while drawing under 1 microampere between conversions. The wide +2.7 V to +5.25 V supply range accommodates the loop voltage after the sense resistor, and the SPI output connects directly to a low-power microcontroller that modulates the loop current. SAR architecture ensures deterministic 7.4 microsecond conversion time suitable for safety-rated update rates. Use the internal 2.5 V reference with ratiometric sensor bridges for highest noise-immunity and best 4-20 mA loop accuracy over temperature.
Được đề xuất
Pen-Digitizer and Touch-Screen Controller
The MAX157AEPA's two-channel single-ended input and 108 ksps throughput make it well suited to resistive touch-screen and pen-digitizer scanning, where X and Y plate voltages are alternately digitized through two ADC channels. The SAR core's 7.4 microsecond acquisition supports smooth 100-point-per-second digitizer sampling with no motion artifacts, and the SPI-compatible serial interface reduces MCU pin count versus parallel ADCs. The industrial -40 to +85C temperature grade supports outdoor kiosk and ruggedized tablet applications. Use external reference for ratiometric touch measurement to cancel excitation drift.
Được đề xuất
Portable Medical Instrumentation
For portable medical instrumentation including pulse oximeters, glucose meters, and patient-worn monitors, the MAX157AEPA's 0.5 LSB INL and 1.2 mA active current deliver measurement-grade accuracy at battery-friendly power. Two single-ended inputs accommodate both a primary sensor channel and a reference/junction-compensation channel on a single chip, halving board area versus dual-ADC designs. The industrial temp grade supports skin-contact and body-proximate applications, while the SPI interface streams data to a low-power MCU for BLE transmission. Use the internal 2.5 V reference or an external precision reference such as the MAX6066 for absolute accuracy in diagnostic devices.
Được đề xuất
Isolated Industrial Sensor Front-End
In isolated 24 V industrial sensor front-ends, the MAX157AEPA digitizes bridge or thermocouple signals at the field end and transmits the digital code across an isolation barrier, eliminating analog isolation cost and noise. Two single-ended channels digitize both the sensor and a cold-junction compensation signal, while the SPI output drives an optocoupler or digital isolator to the controller side. The +2.7 V to +5.25 V supply lets the part operate from the same 5 V rail that powers the isolator LED driver. Use external reference with ratiometric excitation to reject 4 kV common-mode transients on the field side.
Được đề xuất
HVAC and Building Automation Sensors
The MAX157AEPA is well matched to HVAC pressure, flow, and temperature sensor clusters where compact, low-power, multi-channel digitization is required. Two single-ended inputs handle both a primary sensor and a thermistor compensation channel from a 24 VAC-derived 5 V rail, while the industrial -40 to +85C range temp covers rooftop and basement equipment enclosures. The SPI port links directly to a wall-mount controller MCU running Modbus or BACnet, and the part's sub-1 uA power-down current suits battery-backed wireless sensor nodes. Use the internal 2.5 V reference for absolute readings and external reference for ratiometric bridges.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho MAX157AEPA — 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 | MAX157AEPA+ | MAX157BEPA | MAX157BCPA | MAX159AEPA | MAX147AEAP |
|---|---|---|---|---|---|---|
| Package | PDIP-8 | PDIP-8 - same | PDIP-8 - same | PDIP-8 - same | PDIP-8 - same | SSOP-20 - larger |
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Resolution | 10 bit | 10 bit | 10 bit | 10 bit | 10 bit | 12 bit (higher) |
| Number of Channels | 2 single-ended | 2 single-ended | 2 single-ended | 2 single-ended | 1 differential | 8 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 |
| Operating Temperature | -40 C to +85 C (industrial) | -40 C to +85 C | 0 C to +70 C (commercial) | 0 C to +70 C (commercial) | -40 C to +85 C | -40 C to +85 C |
| Interface | SPI/QSPI/MICROWIRE serial | SPI/QSPI/MICROWIRE serial | SPI/QSPI/MICROWIRE serial | SPI/QSPI/MICROWIRE serial | SPI/QSPI/MICROWIRE serial | SPI serial |
| RoHS Status | Non-compliant (legacy) | Compliant (lead-free) | Non-compliant (legacy) | Non-compliant (legacy) | Compliant (plus variant) | Compliant (plus variant) |
Bảo phân biệt quan trọng
- Industry-leading low-power automatic power-down to sub-1 uA between conversions (vsMAX157BCPA)
- RoHS lead-free processing with identical electrical specs (vsMAX157AEPA (non-plus legacy))
- Two single-ended channels in the same 8-pin package (vsMAX159AEPA)
Ghi chú thiết kế
Place a 10 microfarad tantalum and 0.1 microfarat ceramic bypass capacitor as close as possible to the VDD pin (pin 1) of the MAX157AEPA, with the ceramic cap leading. Route the analog ground (pin 5) directly to a single star-ground point shared with the MCU ground, and keep digital return traces (DOUT, SCLK, CS) physically separated from analog input traces (AIN0, AIN1) to avoid digital switching noise coupling into the ADC input.
Drive VDD from a low-noise LDO regulator (for example a MAX1576-class LDO) rather than directly from a switching converter, since the MAX157AEPA's 0.5 LSB INL can be corrupted by switching ripple coupling through the supply pin. For battery-powered designs, take advantage of the sub-1 microampere automatic power-down current between conversions - this is the dominant battery-life factor and is the key reason this ADC is preferred over always-on alternatives.
Do not leave the REF pin floating when using the internal reference - the MAX157AEPA's reference buffer requires the bypass capacitor at REF for stable operation, and omitting it causes gain error and excess noise. When using an external reference, ensure its output impedance is below 50 ohm at DC and that it can drive the REF pin's input current during conversion (typically a few microampere peaks).
Source impedance at AIN0 and AIN1 should be kept below 5 kilohm to avoid IR-drop errors during the 7.4 microsecond acquisition window. Add an external 100 picofarad to 1 nanofarad buffer cap on the input channel if the source impedance exceeds 10 kilohm, or use a unity-gain op-amp buffer such as the MAX4475 ahead of the ADC to drive the switched-capacitor input cleanly.
Thông tin tuân thủ
MAX157AEPA is the legacy non-RoHS variant; for RoHS compliance use the MAX157AEPA+ drop-in. Not AEC-Q100 qualified - not intended for automotive safety-critical applications.
