MAX157BEPA - 10-Bit 108ksps 2-Ch Serial ADC | Maxim Integrated
MPN: MAX157BEPA ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.42 | $6.42 |
| 10 | $5.78 | $57.80 |
| 100 | $4.91 | $491.00 |
| 500 | $4.18 | $2,090.00 |
| 1,000 | $3.62 | $3,620.00 |
MAX157BEPA Overview
An ADC (analog-to-digital converter) is a mixed-signal integrated circuit that quantizes a continuous analog voltage into a discrete digital code. Successive-approximation ADCs use an internal DAC and comparator to binary-search the input against reference-derived levels, trading off conversion speed against die area and power. The MAX157BEPA belongs to the successive-approximation ADC family, which is the dominant topology for general-purpose 8-to-16 bit industrial data-acquisition and instrumentation applications because it delivers a deterministic conversion time and low latency compared with delta-sigma converters.
Key specifications include 2 single-ended input channels, 10-bit resolution, 108 ksps maximum sampling rate, 7.4 µs successive-approximation conversion time, automatic power-down between conversions, fast 2.5 µs wake-up, on-chip clock, and 3-wire serial output. Operating from a single +2.7V to +5.25V supply, the part consumes only 3.2 mW at VDD = +3.6 V at full sampling rate and drops to microamp-level standby current in power-down mode, making it well suited for battery-powered and energy-harvesting designs.
The MAX157BEPA uses a classic switched-capacitor charge-redistribution SAR architecture with an input track-and-hold, internal reference, and an on-chip 4.096 MHz oscillator. This architecture provides excellent linearity, low aperture uncertainty, and deterministic throughput at 108 ksps, supporting both single-shot and continuous conversion sequences without external clock conditioning.
Typical applications include portable data loggers, handheld multimeters, industrial process transmitters, weigh scales, isolated sensor front-ends, panel meters, and consumer measurement equipment. The DIP-8 package suits prototype breadboarding, through-hole production, and socket-based test fixtures where surface-mount parts are impractical. Designers favor this part for its small footprint, single-supply operation, and easy 3-wire interface.
When laying out the PCB, keep analog and digital ground returns short and join them at one star point near the ADC GND pin. Place a 0.1 µF decoupling capacitor within a few millimeters of the VDD pin and a 10 µF bulk cap on the supply for low-noise operation. The input source impedance should stay under 5 kΩ to preserve linearity; add an input buffer if your signal source exceeds this limit.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, including thermal performance, PCB layout recommendations, and a side-by-side comparison against the MAX157BEPA+ and MAX159 same-family variants.
Drop-in alternatives for MAX157BEPA — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MAX157BEPA (same form factor and footprint) — differing in Package, Operating Temperature, Architecture, Number of Channels, Supply Voltage.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX157BEPA+
✅ Drop-In✓ In Stock
$5.21 / Unit
View Datasheet →MAX159BEPA+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX157BCPA
✅ Drop-In✓ In Stock
$3.1 / Unit
View Datasheet →MAX157BEPA Maximum Ratings & Electrical Characteristics
| Number of Channels | 2 single-ended |
| Resolution | 10 bit |
| Sampling Rate | 108 ksps |
| Conversion Time | 7.4 us (successive approximation) |
| Wake-up Time | 2.5 us (from automatic power-down) |
| Supply Voltage (VDD) | +2.7 V to +5.25 V (single supply) |
| Supply Current (Active, VDD=+3.6V) | 3.2 mW typical |
| Supply Current (Power-Down) | uA-level standby |
| Input Type | Single-Ended |
| Data Interface | SPI / QSPI / MICROWIRE-compatible, 3-wire serial |
| Internal Oscillator | 4.096 MHz (on-chip) |
| Configuration | MUX + S/H + SAR ADC |
| Operating Temperature | -40C to +85C (industrial) |
| Package | 8-Pin DIP (PDIP-8), through-hole |
| Mounting Type | Through-Hole |
| Number of Terminals | 8 |
| Terminal Form | Through-Hole |
| Package Code | DIP |
| Temperature Grade | Industrial |
| Architecture | Successive Approximation (SAR) |
MAX157BEPA Pin Configuration
| Pin 1 | AIN1 — Analog input channel 1 (single-ended) |
| Pin 2 | AIN2 — Analog input channel 2 (single-ended) |
| Pin 3 | GND — Ground |
| Pin 4 | VDD — Positive supply (+2.7V to +5.25V) |
| Pin 5 | DOUT — Serial data output (SPI MOSI) |
| Pin 6 | SSTRB — Serial-strobe-conversion output (active low on MAX157) |
| Pin 7 | CS-bar — Chip select (active low) |
| Pin 8 | DIN — Serial data input / serial clock (SPI SCK) |
Typical Applications
MAX157BEPA is suitable for 7 applications: Portable Data Loggers, Handheld Digital Multimeters, Industrial Process Transmitters, Weigh Scales and Load-Cell Front-Ends, Battery Monitoring and Fuel Gauges, Isolated Sensor Interfaces, Consumer Measurement Equipment.
Portable Data Loggers
The MAX157BEPA fits portable data-logger front-ends because it delivers 10-bit, 108 ksps acquisition from a single +2.7V to +5.25V supply and drops to microamp-level standby between conversions with 2.5 µs wake-up. The 2 single-ended input channels accept two sensors (e.g., temperature + humidity) without external multiplexers, while the 3-wire SPI serial stream feeds a low-power MCU such as an MSP430 or PIC directly. Unlike delta-sigma ADCs, the SAR architecture provides deterministic 7.4 µs conversion time so the MCU can stay in sleep until the SSTRB falling edge, simplifying duty-cycle budgeting.
Recommended
Handheld Digital Multimeters
The MAX157BEPA's 108 ksps throughput and 10-bit resolution fit handheld DMM architectures that sample voltage, current, and resistance ranges at the sub-100 kHz rate. The MAX157/MAX159 datasheet typical application shows the ADC digitizing a divided/shunted analog front-end and streaming results via 3-wire SPI to a microcontroller that drives the LCD display. The PDIP-8 through-hole package supports socketed modules that engineers can swap during calibration - unlike SMD parts which require hot-air rework.
Recommended
Industrial Process Transmitters
The MAX157BEPA suits 4-20 mA loop-powered or 2-wire industrial transmitters because it operates from +2.7V to +5.25V (compatible with loop regulators) and consumes only 3.2 mW at VDD = +3.6V at full throughput. Its 7.4 µs SAR conversion time gives deterministic latency for sensor-signal conditioning chains with bridge, RTD, or thermocouple front-ends. The automatic power-down and 2.5 µs wake-up feature lets the system duty-cycle the ADC for sub-mA average current budget on the loop, while the on-chip 4.096 MHz oscillator eliminates the need for an external clock source in space-constrained transmitter heads.
Recommended
Weigh Scales and Load-Cell Front-Ends
The MAX157BEPA digitizes the differential output of a load cell via an external instrumentation amplifier and connects via SPI to a microcontroller that performs calibration, filtering, and tare subtraction. The SAR architecture's inherent 7.4 µs conversion time allows the system to oversample at 108 ksps and average down for noise reduction - a common pattern in entry-level weighing scales that require 10-bit absolute accuracy. The 8-pin PDIP package simplifies hand-soldered prototype calibration jigs used in weigh-scale manufacturing.
Recommended
Battery Monitoring and Fuel Gauges
The MAX157BEPA handles multi-cell battery monitor and fuel-gauge front-ends by sampling pack voltage and current-sense amplifier output through its 2 single-ended channels. Operating from a single +2.7V to +5.25V supply, the ADC directly interfaces to 1S Li-ion (3.3V nom) or multi-cell NiMH packs. The MAX157/MAX159 datasheet's automatic power-down drops quiescent current to microamps between samples, letting the MCU implement Coulomb-counting duty cycles that preserve cell life - critical for backup batteries in alarm panels and remote telemetry units.
Recommended
Isolated Sensor Interfaces
The MAX157BEPA digitizes analog signals on the field side of an isolation barrier and streams the result via SPI to a microcontroller on the controller side via digital isolators. The 3-wire interface (DIN, DOUT, SSTRB-bar) maps cleanly onto 3-channel digital isolators like Maxim's MAX14878 or ADI's ADuM1411, requiring only one isolator chip per ADC. The MAX157/MAX159 datasheet typical application shows the ADC paired with an optocoupler for legacy 4-wire isolation, where the ADC's automatic power-down keeps optical isolator LED current near zero between conversions - extending isolator lifetime.
Recommended
Consumer Measurement Equipment
The MAX157BEPA drives consumer test gear such as bench-top DMMs, light meters, sound-level meters, and temperature probes by converting analog sensor inputs to a 10-bit digital code readable by a low-cost microcontroller. According to the MAX157/MAX159 datasheet, the ADC supports continuous-conversion mode for graphical-display applications where waveform-like readings are sampled at 100+ Hz. The PDIP-8 package suits through-hole consumer product designs and educational/DIY kits where hand-soldering is preferred over SMD.
Recommended
Recommended Products Summary
Engineering reference data for MAX157BEPA — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX157BEPA+ | MAX159BEPA+ | MAX157BCPA | MAX156BENG |
|---|---|---|---|---|---|
| Package | PDIP-8 (through-hole) | PDIP-8 (through-hole) - same | PDIP-8 (through-hole) - same | PDIP-8 (through-hole) - same | PDIP-24 - different |
| Brand | Maxim Integrated | Maxim Integrated - same | Maxim Integrated - same | Maxim Integrated - same | Maxim Integrated - same |
| Resolution | 10 bit | 10 bit | 10 bit | 10 bit (B-grade trim) | 12 bit |
| Number of Channels | 2 single-ended | 2 single-ended | 2 single-ended (unipolar/bipolar) | 2 single-ended | 8 single-ended |
| Data Interface | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI |
| RoHS Compliance | Not RoHS (legacy Pb finish) | RoHS-compliant (Pb-free) | RoHS-compliant (Pb-free) | Not RoHS (legacy) | Not RoHS (legacy) |
Key Differentiators
- Through-hole PDIP-8 footprint with on-chip oscillator (vs MAX157BEUA (uMAX-8 SMD))
- RoHS-compliant variant available as drop-in replacement (vs MAX157BEPA (legacy Pb finish))
- Bipolar input option via MAX159 sister part (vs MAX157BEPA (unipolar only))
Design Notes
Decouple VDD with a 0.1 uF ceramic capacitor placed within 5 mm of pin 4, and add a 10 uF bulk capacitor near the supply pin to suppress digital switching noise. The MAX157/MAX159 datasheet recommends placing the analog and digital grounds as separate traces that join at a single star point near the ADC GND pin (pin 3). Use a low-impedance VDD source; battery-rail applications should include a series ferrite bead if the ADC shares the rail with a digital MCU.
Keep analog input traces (pins 1, 2) short and guarded by a ground trace to reduce digital-noise coupling from the serial interface (pins 5-8). Route DOUT, SSTRB, CS-bar, and DIN away from the analog inputs. The MAX157/MAX159 datasheet cautions that input source impedance should not exceed approximately 5 kohm to preserve acquisition linearity; otherwise add an op-amp buffer (e.g., MAX4162) between the source and AIN1/AIN2.
Do not apply analog inputs before VDD is stable - this can trigger latch-up or out-of-range sampling. Pull CS-bar high (logic high) when the SPI bus is idle to put the MAX157BEPA into power-down automatically (per MAX157/MAX159 datasheet power-down behavior). When migrating between the MAX157 (2 single-ended) and the MAX159 (unipolar/bipolar configurable), remember that the MAX159 requires register reconfiguration via the DIN pin during conversion to enable bipolar ranges - the MAX157 ignores these control bits.
Compliance Information
MAX157BEPA is the legacy Pb-finish variant - the +RoHS-compliant MAX157BEPA+ is preferred for new designs. AEC-Q100 not applicable for this commercial/industrial-grade ADC.
