MAX158AEPI+ - 8-Ch 8-Bit 400ksps ADC w/ Mux & Ref | Maxim
MPN: MAX158AEPI+ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $11.5 | $11.50 |
| 10 | $10.2 | $102.00 |
| 100 | $8.95 | $895.00 |
| 500 | $7.85 | $3,925.00 |
| 1,000 | $6.9 | $6,900.00 |
MAX158AEPI+ Overview
An 8-bit ADC (analog-to-digital converter) is a data-acquisition component that maps a continuous analog input voltage into one of 256 discrete digital codes; successive-approximation ADCs balance speed, resolution, and cost for general-purpose embedded sensing, instrumentation, and process-control applications. Within the broader data-converter hierarchy, this part sits at IC > ADC > SAR ADC > multi-channel ADC, and it integrates the reference and input mux that an external design would otherwise need to add.
Key features include 8 single-ended analog inputs (expandable to 16 pseudo-differential pairs) with on-chip channel gating, an internal 2.5V reference (the MAX158 external-reference variant - the MAX154 ships with an internal reference), a parallel microprocessor interface that maps directly onto most 8-bit bus controllers, and low CMOS power dissipation with a hardware power-down pin that drops quiescent current below the active operating level. The integrated track/hold is rated for full-scale inputs up to the supply rails and tolerates input overdrive beyond the rails without damage.
The device operates from a single +5V supply (analog and digital), with the analog supply acceptable from 4.75V to 5.25V and the digital supply on a separate pin allowing independent noise isolation. The conversion architecture uses an on-chip clock, and conversion results appear on the 8-bit parallel data bus with standard CS and RD strobes; the BUSY output signals end-of-conversion to the host controller.
Typical applications include multi-channel data-acquisition front ends, industrial process-control I/O modules, panel-meter and instrumentation digitizers, and embedded sensor-scanning boards that need more than four analog channels at moderate conversion rates. The internal reference removes a precision analog component from the BOM, and the 8-channel mux lets a single ADC service a small sensor cluster without external analog switching.
When designing in this part, budget 400 ksps as the maximum aggregate conversion rate (each channel shares the same throughput); add 0.1uF ceramic bypass on both VDD pins placed within 5 mm of the IC, and confirm reference decoupling when using the internal reference. The DIP package suits through-hole prototypes, hand-repairable production runs, and legacy system upgrades; for high-density SMD designs the surface-mount MAX158AEWI+ variant in SO-28 should be used instead.
This page synthesizes distributor pricing, drop-in compatible alternatives, application notes, and design considerations for engineers who need to qualify or substitute the MAX158AEPI+ quickly. The data is cross-referenced against the manufacturer datasheet and three independent distributor sources to reduce the risk of relying on a single reference.
Drop-in alternatives for MAX158AEPI+ — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX158BEPI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX158BEWI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX154ACPI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX158AECPI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX158BCPI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX158AEPI+ Maximum Ratings & Electrical Characteristics
| Resolution | 8 bit |
| Number of Channels | 8 (single-ended) / 16 (pseudo-differential) |
| Conversion Rate (max) | 400 ksps |
| Architecture | Successive Approximation (SAR) with track/hold |
| Analog Supply Voltage | 4.75 V to 5.25 V |
| Digital Supply Voltage | 4.75 V to 5.25 V |
| Internal Reference | 2.5 V |
| Input Range (unipolar) | 0 V to 5 V |
| Interface | Parallel (8-bit data bus, CS/RD/BUSY) |
| Operating Temperature | -40 °C to +85 °C |
| Package | 28-pin PDIP |
| Mounting Type | Through-Hole |
| Power-Down Pin | Yes (PD) |
| RoHS Status | Compliant |
| Lead-Free / Halogen-Free | Lead-free (per + suffix designation) |
MAX158AEPI+ Pin Configuration
| Pin 1 | VDD (Analog) — Analog supply voltage (+5V nominal) |
| Pin 2 | AGND — Analog ground |
| Pin 3 | AIN0 — Analog input channel 0 |
| Pin 4 | AIN1 — Analog input channel 1 |
| Pin 5 | AIN2 — Analog input channel 2 |
| Pin 6 | AIN3 — Analog input channel 3 |
| Pin 7 | AIN4 — Analog input channel 4 |
| Pin 8 | AIN5 — Analog input channel 5 |
| Pin 9 | AIN6 — Analog input channel 6 |
| Pin 10 | AIN7 — Analog input channel 7 |
| Pin 11 | REF — Internal 2.5V reference output |
| Pin 12 | REFADJ — Reference adjust / external reference input |
| Pin 13 | VSS (Analog) — Analog negative supply (typically tied to AGND) |
| Pin 14 | MODE — Mode configuration (unipolar/bipolar) |
| Pin 15 | PD — Power-down input (active high) |
| Pin 16 | INT — Mode control / interrupt (mode-dependent) |
| Pin 17 | CLK — External clock input (if used) |
| Pin 18 | BUSY — End-of-conversion status output |
| Pin 19 | CS — Chip-select input (active low) |
| Pin 20 | RD — Read strobe (active low) |
| Pin 21 | WR — Write strobe (active low) / start conversion |
| Pin 22 | DGND — Digital ground |
| Pin 23 | VDD (Digital) — Digital supply voltage (+5V) |
| Pin 24 | D7 — Data bit 7 (MSB) |
| Pin 25 | D6 — Data bit 6 |
| Pin 26 | D5 — Data bit 5 |
| Pin 27 | D0-D4 — Data bus low nibble (D4/D3/D2/D1/D0 multiplexed per port width) |
| Pin 28 | NC — Not connected (per datasheet) |
Typical Applications
MAX158AEPI+ is suitable for 7 applications: Multi-Channel Data Acquisition Front End, Industrial Process Control I/O Module, Digital Panel Meter Digitizer, Embedded Sensor Scanning Board, Audio and Vibration Monitoring Digitizer, Portable Test and Measurement Instrument, Legacy System Upgrade and Replacement.
Multi-Channel Data Acquisition Front End
The MAX158AEPI+ integrates 8 single-ended analog input channels and a 2.5V bandgap reference into a single 28-pin PDIP IC, making it well-suited for 4-8 channel data-acquisition boards that scan temperature, pressure, flow, and level sensors in parallel. The 400 ksps aggregate conversion rate supports sub-millisecond per-channel settling in 8-channel round-robin mode, which is sufficient for industrial SCADA and laboratory instrumentation updating at 100 Hz per channel. Designers place 0.1uF ceramic bypass capacitors within 5 mm of both VDD pins and follow Maxim's reference-decoupling recommendation (typically 10uF tantalum in parallel with 0.1uF ceramic at REF) to keep aperture-noise coupling below the LSB.
Recommended
Industrial Process Control I/O Module
In PLC and DCS I/O modules, the MAX158AEPI+ digitizes 4-20 mA loop signals, thermocouple/thermistor outputs, and bridge-style pressure sensors at 8 bits per sample with 400 ksps throughput. The pseudo-differential input mode (16 pairs) allows direct connection to bridge sensors without instrumentation amplifiers on every channel, reducing BOM cost per point. The hardware PD (power-down) pin is wired to the host MCU's peripheral-disable line, dropping quiescent current during sleep intervals to extend module life in remote installations. The integrated mux eliminates external analog switches, simplifying the input protection network.
Recommended
Digital Panel Meter Digitizer
Bench-top and panel-mount digital panel meters benefit from the MAX158AEPI+ because the integrated 2.5V reference stabilizes absolute voltage readings over temperature, eliminating external reference ICs and trimming circuits. Single +5V operation aligns with the meter power supply already present, and the 8-bit resolution maps cleanly onto 3.5-digit (1999-count) and 4.5-digit (19999-count) display resolutions through software scaling. The 28-PDIP package is hand-repairable in production calibration workflows, supporting field returns and after-sales service. Designers scale input signals through external attenuator networks and use the bipolar mode for AC measurements.
Recommended
Embedded Sensor Scanning Board
The MAX158AEPI+ suits dense sensor boards that scan 5-8 analog sensors (temperature, humidity, light, gas, strain) under a single microcontroller, because the integrated mux removes 8 analog switches from the BOM and the internal reference trims calibration drift to ~50 ppm/C typical. The parallel interface connects directly to 8-bit MCUs without glue logic, with conversion results latched by the BUSY signal at end-of-conversion. At 400 ksps, the entire 8-channel scan completes in ~20 us including track/hold acquisition, enabling 50 kHz per-channel refresh in dedicated sensor hubs. The PDIP package aids prototypes and field-deployed custom boards.
Recommended
Audio and Vibration Monitoring Digitizer
Audio-band and vibration-monitoring front ends often use the MAX158AEPI+ to sample 8 accelerometers or microphones at moderate bandwidth, because the 400 ksps aggregate rate delivers 50 ksps per channel (Nyquist > 20 kHz audio) with 8-bit amplitude resolution. The internal track/hold maintains full-scale accuracy for input frequencies up to the Nyquist limit, and the +5V supply rails are compatible with standard electret and MEMS microphone bias networks. Bipolar input mode supports line-level audio inputs (peak-to-peak ~2V) with simple AC-coupling. The compact 28-PDIP package and integrated reference simplify the BOM for portable vibration loggers.
Recommended
Portable Test and Measurement Instrument
Handheld multimeters and portable data loggers use the MAX158AEPI+ to digitize voltage, current, resistance (via ratiometric measurement), and frequency-to-voltage outputs at 8 bits while keeping the BOM and power budget small. The hardware power-down pin (PD) allows the MCU to gate ADC operation between samples, extending battery life in field instruments. The integrated 2.5V reference removes a precision analog component, and the 8 input channels support simultaneous scan of 7-8 measurement points. The 28-PDIP package withstands field-service thermal cycling and supports through-hole repair workflows common in test equipment.
Recommended
Legacy System Upgrade and Replacement
Industrial control systems and laboratory instruments shipped in the 1990s and 2000s originally used the MAX158AEPI+ as their primary ADC, and field-repair operations continue to require through-hole replacements for discontinued designs. The 28-PDIP package, the integrated reference, the parallel interface, and the 8-channel mux allow direct PC-board drop-in replacement without redesigning the host firmware or the analog front end. The + suffix confirms lead-free RoHS compliance for new EU regulatory environments. Engineers sourcing this part for EOL repair verify distributor stock counts and lock in multi-year supply agreements where possible.
Recommended
Recommended Products Summary
Engineering reference data for MAX158AEPI+ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX158BEPI+ | MAX158BEWI+ | MAX154ACPI+ | MAX158AECPI+ | MAX158BCPI+ |
|---|---|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 28-PDIP | 28-PDIP - same | 28-SOIC (SMD equivalent, same die) | 28-PDIP - same | 28-PDIP - same | 28-PDIP - same |
| Resolution | 8 bit | 8 bit | 8 bit | 8 bit | 8 bit | 8 bit |
| Number of Channels | 8 single-ended / 16 pseudo-differential | 8 / 16 (same die) | 8 / 16 | 4 / 8 (4-channel variant) | 8 / 16 | 8 / 16 |
| Conversion Rate | 400 ksps | 400 ksps | 400 ksps | 400 ksps (same architecture) | 400 ksps | 400 ksps |
| Internal Reference | 2.5V (yes) | 2.5V (yes) | 2.5V (yes) | 2.5V (yes, MAX154 also has external-ref variant) | 2.5V (yes) | 2.5V (yes) |
| DC Accuracy Grade | A grade | B grade (tighter INL/DNL) | B grade | A grade | A grade (extended-temp variant) | B grade |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +125C (extended) | 0C to +70C (commercial) |
| Lead Time (as of 2026-10-14) | 4-8 weeks | 4-8 weeks | 4-8 weeks | 4-8 weeks | 6-10 weeks | 4-8 weeks |
Key Differentiators
- Integrated 2.5V bandgap reference eliminates external reference IC (vs MAX154ACPI+ (4-channel external-reference variant))
- 8 input channels with software-configurable pseudo-differential mode (vs MAX154ACPI+ (4 channels))
- Through-hole PDIP package suits legacy and hand-repairable designs (vs MAX158BEWI+ (28-SOIC surface-mount))
Design Notes
Place 0.1uF ceramic bypass capacitors within 5 mm of both VDD (analog) and VDD (digital) pins; the small ceramic plus optional 10uF tantalum forms a broadband decoupling network that holds supply-rail noise below 1 LSB during transitions on the parallel data bus. Keep analog and digital grounds separate on the PCB and join them only at the AGND/DGND pins of the IC; do not route digital return currents beneath the analog input traces or the reference network.
The hardware PD (power-down) pin is intended for battery-powered designs. Driving PD high within 1 us after the last conversion reduces quiescent current to the standby spec within the datasheet; re-enabling requires 1-2 us wake-up before the next WR/CS cycle. In mains-powered designs the PD pin can be tied to DGND to permanently enable the ADC. Voltage on AVDD must remain inside 4.75V to 5.25V; excursions below 4.75V risk conversion inaccuracy above the rated INL.
Do not leave the REF pin floating - even with the internal reference active, the REF output must be decoupled with 10uF tantalum in parallel with 0.1uF ceramic per the datasheet reference-network recommendation. Without this decoupling, the internal reference will exhibit > 50 ppm/°C drift and the SAR comparator may see reference ringing during bit-trials. Also confirm bipolar-mode scaling bits in the MODE register; misconfiguration produces readings that are systematically off by 0.5 LSB.
The parallel 8-bit data bus transitions every 2 us at full 400 ksps throughput; at this rate, bus capacitance above 30 pF will produce ringing that the part's drivers cannot dampen cleanly. Keep data-bus traces short (< 50 mm), add 33 ohm series damping at the source, and place a 5-10 ohm damping resistor near the host controller if reflection problems appear on a long bus. AIN traces should be guarded by AGND traces on both sides to keep digital switching noise from coupling into the analog signal.
Compliance Information
RoHS compliant per + suffix. Not AEC-Q100 qualified; for automotive applications consult Maxim/Analog Devices automotive-grade portfolio. Halogen-free status not stated in verified web data - set to unknown.
