MAX128AEAI - 12-Bit 8ksps 8-Ch 2-Wire Serial ADC | Maxim
N.º de pieza: MAX128AEAI ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $21.5 | $21,50 |
| 10 | $19.35 | $193,50 |
| 100 | $17.21 | $1.721,00 |
| 500 | $15.48 | $7.740,00 |
| 1.000 | $14.04 | $14.040,00 |
MAX128AEAI Descripción general
A SAR ADC (Successive Approximation Register Analog-to-Digital Converter) is a type of data converter that resolves one bit per clock cycle through a binary-search internal DAC. SAR ADCs sit within the broader ADC taxonomy (Flash < SAR < Sigma-Delta in speed-resolution trade-off), and they belong to the data-converter category of mixed-signal ICs. The MAX128 family packages the SAR core, an input multiplexer, a reference buffer, and a 2-wire digital interface into a single chip, replacing a discrete ADC plus external MUX plus interface logic with one IC.
Key features that differentiate the MAX128AEAI from generic 8-channel ADCs include its integrated reference buffer (eliminating the external bypass capacitor and startup delay in standby mode), 2-wire I2C-compatible interface (saving 4 to 6 GPIOs versus a parallel interface), and ±16.5V fault-protected inputs (allowing direct connection to industrial 4-20 mA loops and ±12V analog rails without external protection). The 1/2 LSB integral non-linearity and 8 ksps throughput are tuned for low-frequency precision signals rather than audio bandwidth.
Architecturally, the MAX128AEAI uses a capacitive charge-redistribution SAR core, an 8-channel analog input MUX, an on-chip reference buffer, and an I2C-compatible slave controller. In standby mode the reference buffer remains active, eliminating the 1-2 ms startup delay that plagues many competitor ADCs and enabling rapid wake-and-sample response in duty-cycled battery applications.
Typical applications include multichannel data acquisition front-ends, industrial process-control PLC analog input modules, battery-powered portable instrumentation, and robotics sensor interface boards. The 4 software-selectable ranges (0-VREF, 0-VREF/2, ±VREF, ±VREF/2) make it suitable for both single-supply 0-5V sensors and bipolar ±12V industrial signals using an external reference.
When designing with this device, place the 0.1 uF VDD bypass capacitor as close as possible to pin 28 and follow the 2-wire I2C address-select convention documented in the datasheet. The two AS (Address Select) pins allow up to 4 MAX128 devices on a single I2C bus, expanding the channel count to 32 without a separate bus multiplexer.
This page synthesizes distributor pricing, drop-in pin-compatible alternatives, application-circuit recommendations, and 2-wire interface design notes not found in the manufacturer datasheet alone.
Alternativas directas para MAX128AEAI — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con MAX128AEAI (mismo factor de forma y huella) — difiere en Package, Supply Voltage, Architecture, Mounting Type, Input Ranges.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
MAX128BCAI
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
MAX128ACAI
✅ Sustitución directa✓ En stock
$15.19 / unidad
Ver hoja de datos →MAX128AEAI+T
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
MAX127BEAI+T
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
MAX1270BENG
✅ Sustitución directa ⚠️ Especificaciones sin verificar✓ En stock
$19.85 / unidad
Ver hoja de datos →MAX128AEAI Valores máximos y características eléctricas
| Resolución | 12 bits |
| Frecuencia de muestreo | 8 ksps |
| Number of Input Channels | 8 analog inputs |
| Tensión de alimentación | +5 V single supply |
| Serial Interface | 2-wire I2C-compatible |
| Input Ranges | 0 to VREF, 0 to VREF/2, ±VREF, ±VREF/2 (4 software-selectable) |
| Integral Non-Linearity (INL) | 1/2 LSB (max) |
| Overvoltage Tolerance | ±16.5 V |
| Reference Buffer | Internal, active in standby (eliminates startup delay) |
| Address Select Pins | 2 (AS0, AS1 - allows 4 devices per I2C bus, up to 32 channels) |
| Encapsulado | 28-pin SSOP |
| Tipo de montaje | Surface Mount |
| Operating Temperature Grade | Industrial (A suffix) |
| Architecture | SAR (Successive Approximation Register) |
Configuración de pines de MAX128AEAI
| Pin 1 | AIN0 — Analog input channel 0 |
| Pin 2 | AIN1 — Analog input channel 1 |
| Pin 3 | AIN2 — Analog input channel 2 |
| Pin 4 | AIN3 — Analog input channel 3 |
| Pin 5 | AIN4 — Analog input channel 4 |
| Pin 6 | AIN5 — Analog input channel 5 |
| Pin 7 | AIN6 — Analog input channel 6 |
| Pin 8 | AIN7 — Analog input channel 7 |
| Pin 9 | AGND — Analog ground |
| Pin 10 | REF — External reference voltage input |
| Pin 11 | SDA — 2-wire serial data (open-drain, requires pull-up) |
| Pin 12 | SCL — 2-wire serial clock (open-drain, requires pull-up) |
| Pin 13 | AS0 — Address select 0 (sampled at power-up) |
| Pin 14 | AS1 — Address select 1 (sampled at power-up) |
| Pin 15 | NC — Not connected (per datasheet) |
| Pin 16 | NC — Not connected (per datasheet) |
| Pin 17 | NC — Not connected (per datasheet) |
| Pin 18 | NC — Not connected (per datasheet) |
| Pin 19 | NC — Not connected (per datasheet) |
| Pin 20 | NC — Not connected (per datasheet) |
| Pin 21 | NC — Not connected (per datasheet) |
| Pin 22 | NC — Not connected (per datasheet) |
| Pin 23 | NC — Not connected (per datasheet) |
| Pin 24 | NC — Not connected (per datasheet) |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | NC — Not connected (per datasheet) |
| Pin 28 | VDD — +5V power supply input |
Aplicaciones típicas
MAX128AEAI es adecuado para 6 aplicacións: Industrial PLC Analog Input Module, Multichannel Data Acquisition Front-End, Battery-Powered Portable Instrumentation, Robotics Sensor Interface Board, Process Control Loop Monitoring, Medical Patient Monitor Analog Front-End.
Industrial PLC Analog Input Module
The MAX128AEAI fits 4-20 mA loop monitoring and ±10V industrial signal acquisition thanks to its ±16.5V overvoltage-tolerant inputs and bipolar ±VREF/2 input range. Placed on a 16-32 channel PLC input card with current-sense resistors of 250 ohm, the ADC handles 8 channels per chip with 12-bit (0.024%) resolution per count at the 4-20 mA scale. The 2-wire I2C interface connects to the PLC's microcontroller with only 2 GPIO pins, freeing board space for additional I/O. Unlike discrete ADC + MUX + protection designs, the integrated overvoltage clamp eliminates external TVS diodes and fuses, reducing BOM cost by 30-40% per channel.
Recomendado
Multichannel Data Acquisition Front-End
In a bench or rack-mount data-acquisition system, the MAX128AEAI's 8 ksps sampling rate and 8 single-ended input channels make it well suited for low-frequency transducer signal chains (strain gauges, thermocouples via front-end amplifiers, RTDs). The internal reference buffer that stays active in standby mode eliminates the 1-2 ms wake-up delay of competing ADCs, allowing faster scan-start response in duty-cycled battery-powered loggers. Designers can stack 4 devices on one I2C bus for 32 channels per bus without a separate multiplexer IC, simplifying firmware and reducing PCB area.
Recomendado
Battery-Powered Portable Instrumentation
Battery-powered handheld multimeters and field instruments benefit from the MAX128AEAI's 8 ksps throughput, low-power shutdown mode, and +5V single-supply operation, which pairs naturally with Li-ion (3.6-4.2V) post-regulation to 5V. The standby reference buffer cuts the wake-and-sample latency from 1-2 ms to under 100 us, enabling instant-on measurement at the press of a button - critical for handheld UX. With 8 channels, one chip can read voltage, current, temperature (via thermistor), and 4 resistance ranges in a single DMM design.
Recomendado
Robotics Sensor Interface Board
Robotic platforms require multiple analog sensor channels (motor current, joint position via potentiometer, force-feedback strain gauges, battery voltage, temperature) read by a central MCU. The MAX128AEAI's 8 channels per chip and 2-wire I2C interface let a robot's main controller read up to 32 sensors over 4 devices on one bus, with minimal GPIO consumption. The ±16.5V fault tolerance protects against motor-back-EMF transients that routinely appear on shared wiring harnesses in mobile robots.
Recomendado
Process Control Loop Monitoring
Process-control systems in chemical plants and HVAC equipment use the MAX128AEAI to digitize 4-20 mA current loops and 0-10V control signals from field-mounted sensors. The four software-selectable input ranges (0-VREF, 0-VREF/2, ±VREF, ±VREF/2) let one chip handle both unipolar 4-20 mA (with 250 ohm sense = 1-5V) and bipolar ±10V signals without hardware reconfig, simply by writing the configuration register. Industrial temperature range (-40C to +85C) ensures operation in unconditioned control cabinets.
Recomendado
Medical Patient Monitor Analog Front-End
Patient monitors measuring ECG, SpO2, respiration, temperature, and blood-pressure cuff pressure use the MAX128AEAI for low-speed precision digitizing of conditioned analog signals. The 1/2 LSB INL and 8 ksps rate are well-matched to ECG (typically 500 Hz) and SpO2 (typically 100 Hz) post-amplifier signals. The 8 channels per chip allow one ADC to handle multiple vital signs in compact bedside monitor designs, while the I2C interface reduces wiring to the host processor and helps meet medical EMI/EMC isolation requirements.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para MAX128AEAI — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | MAX128BCAI | MAX128ACAI | MAX128AEAI+T |
|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 28-pin SSOP | 28-pin SSOP - same | 28-pin SSOP - same | 28-pin SSOP - same |
| Resolution | 12 bits | 12 bits | 12 bits | 12 bits |
| Sampling Rate | 8 ksps | 8 ksps | 8 ksps | 8 ksps |
| Input Channels | 8 | 8 | 8 | 8 |
| Interface | 2-wire I2C-compatible | 2-wire I2C-compatible | 2-wire I2C-compatible | 2-wire I2C-compatible |
| Overvoltage Tolerance | ±16.5 V | ±16.5 V | ±16.5 V | ±16.5 V |
| INL (max) | 1/2 LSB | 1/2 LSB (per JAK cross-reference) | 1/2 LSB | 1/2 LSB |
| Packaging Format | Tube | Tube or T&R | Tube or T&R | Tape & Reel |
Diferenciadores clave
- On-chip reference buffer active in standby (frente a MAX128AEAI vs generic 8-channel ADCs (e.g. ADS7830))
- ±16.5V overvoltage-tolerant inputs (frente a MAX128AEAI vs MAX1156AEUP+T)
- 2-wire I2C-compatible interface vs SPI competitor parts (frente a MAX128AEAI vs MAX1147BEUP+T (SPI interface))
- Four software-selectable input ranges (frente a MAX128AEAI vs MAX1162ACUB+T (single range))
Notas de diseño
The MAX128AEAI requires a clean +5V analog supply. Place a 10 uF bulk tantalum or ceramic capacitor and a 0.1 uF ceramic bypass within 5 mm of the VDD pin (pin 28). For mixed-signal boards, isolate the ADC's VDD from noisy digital supplies using a ferrite bead or filter resistor; the AGND pin (pin 9) should connect to the analog ground plane that ties back to the system star ground at the +5V regulator. Estimated: with all 8 channels switching at 8 ksps, average VDD current is approximately 1-2 mA per the datasheet - verify with bench measurement.
Do not leave the REF pin floating. The MAX128AEAI requires an external reference voltage at pin 10; a missing or low-quality reference (e.g. directly using VDD) will degrade linearity. Use a low-noise 4.096V or 5.0V reference such as the MAX6126 or MAX6190 with 10 uF + 0.1 uF local bypass. The I2C bus SDA (pin 11) and SCL (pin 12) require external pull-up resistors (typically 4.7 kohm at 100 kHz, 2.2 kohm at 400 kHz) - the MAX128 has open-drain drivers and cannot drive the bus high without pull-ups.
Route the analog input traces (pins 1-8) as short and as directly above the analog ground plane as possible. Keep digital traces (SDA, SCL, AS0, AS1) physically separated from analog input traces; if crossing is unavoidable, cross at 90 degrees. Place a ground guard ring around each analog input pad to minimize digital-to-analog crosstalk. The exposed pad (if present on the package variant) should be soldered to the analog ground plane for thermal relief and ground impedance reduction.
At 8 ksps and 12-bit resolution, the analog input must settle to within 1/2 LSB (0.024% of full scale) before the SAR conversion starts. The internal acquisition time is typically 1.5 us; if the source impedance is above 1 kohm, add an external input buffer (e.g. MAX4163 op-amp) to avoid conversion errors. For multiplexing between channels, allow at least 3 us of settling time after switching the MUX before triggering conversion, especially when switching from a high-voltage channel to a low-voltage channel.
Información de cumplimiento
RoHS compliant per Maxim Integrated product page. Industrial temperature grade (-40C to +85C, 'A' suffix) - not AEC-Q100 qualified (automotive not target application). Lead-free and halogen-free per Maxim/Analog Devices environmental compliance.