MAX157AEPA - 108ksps 10-Bit 2-Ch Serial ADC | Maxim Integrated
MPN： MAX157AEPA ✓ 啟用中MAX157AEPA 概覽
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.
直接替換替代品，適用於 MAX157AEPA — 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： MAX157AEPA （相同外形與佔位） — 差異在於 Architecture, Conversion Time, Operating Temperature, Package, RoHS Status.
MAX157AEPA+
✅ 直接替換📋 參考替代品（不在目錄中）
MAX157BEPA
✅ 直接替換聯絡詢價
查看資料表 →MAX157BCPA
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →MAX159AEPA
✅ 直接替換📋 參考替代品（不在目錄中）
MAX147AEAP
✅ 直接替換聯絡詢價
查看資料表 →MAX157AEPA 最大額定值與電氣特性
| 解析度 | 10 bit |
| Number of Channels | 2 |
| 取樣率 | 108 ksps |
| Conversion Time | 7.4 us |
| 供應電壓 | +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) |
| 介面 | SPI/QSPI/MICROWIRE-compatible serial |
| INL | +/- 0.5 LSB (max) |
| DNL | +/- 1 LSB (max) |
| Reference | Internal 2.5 V or external up to VDD |
| 工作溫度 | -40 C to +85 C (industrial) |
| 封裝 | PDIP-8 (through-hole, 0.300 in) |
| Architecture | SAR (successive-approximation register) |
| Shutdown Pin | Yes (active-low SHDN) |
| 安裝類型 | Through-Hole |
| RoHS 狀態 | Compliant (MAX157AEPA+ variant) |
MAX157AEPA 腳位配置
| 腳位 1 | VDD — Analog and digital supply, +2.7 V to +5.25 V |
| 腳位 2 | AIN1 — Analog input channel 1 (single-ended) |
| 腳位 3 | AIN0 — Analog input channel 0 (single-ended) |
| 腳位 4 | REF — Reference input/output (internal 2.5 V or external) |
| 腳位 5 | GND — Ground (analog and digital star-ground) |
| 腳位 6 | DOUT — Serial data output, MSB first |
| 腳位 7 | SCLK — Serial clock input |
| 腳位 8 | CS — Active-low chip select / shutdown |
典型應用
MAX157AEPA 適用於 6 應用s: 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.
推薦
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.
推薦
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.
推薦
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.
推薦
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.
推薦
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.
推薦
推薦產品摘要
工程參考資料，適用於 MAX157AEPA — 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 | 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) |
主要差異化特點
- Industry-leading low-power automatic power-down to sub-1 uA between conversions (對比MAX157BCPA)
- RoHS lead-free processing with identical electrical specs (對比MAX157AEPA (non-plus legacy))
- Two single-ended channels in the same 8-pin package (對比MAX159AEPA)
設計說明
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.
合規資訊
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.
