MAX1091BEEI+T - 10-Bit 250ksps 8-Ch SAR ADC w/ Reference | Maxim
MPN: MAX1091BEEI+T ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $11.2 | $11.20 |
| 10 | $10.05 | $100.50 |
| 100 | $8.95 | $895.00 |
| 500 | $8.05 | $4,025.00 |
| 1,000 | $7.3 | $7,300.00 |
MAX1091BEEI+T Overview
An ADC (analog-to-digital converter) is a mixed-signal integrated circuit that quantizes a continuous analog input voltage into a discrete binary code. Within the broader taxonomy, the MAX1091 belongs to SAR ADCs -> data converters -> data acquisition ICs -> signal chain -> semiconductor. SAR architectures use a binary-search capacitor DAC and a single comparator to resolve N bits in N clock cycles, trading speed for excellent DC accuracy, intrinsic monotonicity, and zero pipeline latency. That makes them the dominant choice for multiplexed multi-channel systems, precision instrumentation, and control loops where a deterministic per-channel conversion time matters more than raw throughput.
Key differentiating features of the MAX1091 include 8 single-ended analog input channels (vs. 4 on the MAX1093), 250 ksps maximum sample rate, true 10-bit linearity with no missing codes, an internal +2.5 V reference (also usable as an external drive), hardware- and software-configurable power-down modes that drop supply current to microamp levels between conversions, and an on-chip 4 MHz SAR oscillator that eliminates the need for an external clock. The wide +1.8 V to +5.5 V VLOGIC range lets the part drop directly onto the bus of 1.8 V DSPs, 2.5 V FPGAs, 3.3 V ASICs or 5 V microcontrollers without level shifters.
Architecturally, the device integrates an 8:1 input mux, a fully differential switched-capacitor DAC, an internal +2.5 V bandgap reference, a comparator, a successive-approximation register, a wide parallel output latch, and the power-down/wake-up sequencer. Automatic power-down between conversions keeps average current extremely low in low-duty-cycle applications; in continuous 250 ksps operation the part draws a few milliamps from AVDD and a fraction of that from DVDD.
Typical applications include 4–20 mA sensor-conditioning front ends, portable data loggers, battery-powered medical instrumentation, multi-channel PLC analog input modules, and touch/position sensing front ends. The +3 V single-supply operation, internal reference and tiny QSOP-28 footprint also make it attractive for space-constrained designs that still need more than 4 channels.
When designing with this part, observe the AVDD/DVDD decoupling guidelines in the Maxim datasheet: place a 0.1 µF ceramic close to each supply pin and a bulk tantalum or ceramic on AVDD, keep analog input traces short and guarded, and bypass REF to AGND with the recommended 4.7 µF capacitor to minimize reference noise. The internal reference has limited drive capability, so treat REF as a low-current bias node, not a system rail.
Drop-in alternatives for MAX1091BEEI+T — 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 MAX1091BEEI+T (same form factor and footprint) — differing in Number of Input Channels, Package, Input Type, Architecture, Resolution.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX1091BCEI+T
✅ Drop-In✓ In Stock
$8.1 / Unit
View Datasheet →MAX1091ACEI+T
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →MAX1093BEEI+T
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MAX1091BEEI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1060BEEI+T
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$6.55 / Unit
View Datasheet →MAX1091BEEI+T Maximum Ratings & Electrical Characteristics
| Resolution | 10 bit |
| Sample Rate | 250 ksps |
| Number of Input Channels | 8 single-ended |
| Architecture | SAR (Successive Approximation) |
| Analog Supply Voltage (AVDD) | +3 V (typ), see datasheet for range |
| Digital I/O Supply (VLOGIC) | +1.8 V to +5.5 V |
| Internal Reference | +2.5 V |
| External Reference Option | Yes (REF pin) |
| Interface | Byte-wide parallel (8-bit bus) |
| On-Chip Clock | 4 MHz internal oscillator |
| Power-Down Mode | Automatic, hardware and software controllable |
| Wake-Up Time | 2 µs |
| Package / Pin Count | 28-pin QSOP |
| Operating Temperature Range | -40 °C to +85 °C (industrial) |
| Mounting Type | Surface Mount |
| Lead-Free / RoHS | Yes (per Maxim product page) |
MAX1091BEEI+T Pin Configuration
| Pin 1 | AGND — Analog ground |
| Pin 2 | AVDD — +3 V analog supply |
| Pin 3 | REF — Internal +2.5 V reference / external reference input |
| Pin 4 | AIN0 — Analog input channel 0 |
| Pin 5 | AIN1 — Analog input channel 1 |
| Pin 6 | AIN2 — Analog input channel 2 |
| Pin 7 | AIN3 — Analog input channel 3 |
| Pin 8 | AIN4 — Analog input channel 4 |
| Pin 9 | AIN5 — Analog input channel 5 |
| Pin 10 | AIN6 — Analog input channel 6 |
| Pin 11 | AIN7 — Analog input channel 7 |
| Pin 12 | DGND — Digital ground |
| Pin 13 | VLOGIC — Digital I/O supply (+1.8 V to +5.5 V) |
| Pin 14 | D0/D8 — Data bit 0 (parallel mode) / bit 8 (byte mode) |
| Pin 15 | D1/D9 — Data bit 1 (parallel mode) / bit 9 (byte mode) |
| Pin 16 | D2 — Data bit 2 |
| Pin 17 | D3 — Data bit 3 |
| Pin 18 | D4 — Data bit 4 |
| Pin 19 | D5 — Data bit 5 |
| Pin 20 | D6 — Data bit 6 |
| Pin 21 | D7 — Data bit 7 |
| Pin 22 | INT — Conversion-end interrupt output |
| Pin 23 | CS — Chip select (active low) |
| Pin 24 | RD — Read strobe (active low) |
| Pin 25 | PD — Power-down input |
| Pin 26 | HBEN — High-byte enable (selects MSB byte on D0-D7) |
| Pin 27 | CLK — External clock input (internal 4 MHz oscillator if tied high) |
| Pin 28 | DGND — Digital ground |
Typical Applications
MAX1091BEEI+T is suitable for 6 applications: Multi-Channel Sensor Data Acquisition, Portable Battery-Powered Instrumentation, Industrial PLC Analog Input Modules, Medical Monitoring and Diagnostic Equipment, Automotive Infotainment / Body Electronics (Non-Safety), Touch / Position Sensing Front Ends.
Multi-Channel Sensor Data Acquisition
The MAX1091BEEI+T is well-matched to multi-channel sensor DAQ modules because it integrates an 8:1 input mux, 10-bit SAR ADC, +2.5 V reference, and parallel interface in a single 28-pin QSOP. Its 250 ksps throughput allows full-mux round-robin scanning of thermocouples, strain gauges and 4-20 mA conditioned signals at >30 ksps per channel, while automatic power-down between conversions drops average supply current into the microamp range. Use it where the BOM must stay small but more than 4 channels are needed.
Recommended
Portable Battery-Powered Instrumentation
For handheld multimeters, portable loggers, and field instruments, the MAX1091BEEI+T runs from a single +3 V analog supply while the VLOGIC pin lets the parallel bus talk directly to a 1.8 V or 3.3 V host MCU. Its automatic hardware/software power-down with 2 µs wake-up keeps duty-cycled scans inexpensive in current budget. Combined with the 10-bit resolution, it gives more than enough dynamic range for thermocouple and bridge-sensor readouts while extending battery life versus a continuously-clocked ADC.
Recommended
Industrial PLC Analog Input Modules
Programmable logic controllers and process-control I/O modules benefit from the MAX1091BEEI+T's 8 single-ended channels and byte-wide parallel interface, which maps cleanly onto 8-bit microcontroller buses and FPGA GPIO. The +3 V analog supply and VLOGIC rail simplify mixed 3.3 V/5 V designs, while the internal +2.5 V reference eliminates an external reference IC and its associated drift budget. Industrial -40 °C to +85 °C operation is supported across all 8 channels with channel-to-channel matching defined in the datasheet.
Recommended
Medical Monitoring and Diagnostic Equipment
Patient monitors, bedside diagnostic devices, and portable medical instruments need low-noise, low-power multi-channel conversion that fits a small board. The MAX1091BEEI+T provides 10-bit SAR conversion with deterministic latency (no pipeline delay), so each channel's reading is available in a fixed number of clock cycles - critical for control loops and alarm decision making. Single +3 V operation plus automatic power-down helps meet IEC 60601-1-8 battery and patient-safety leakage budgets while keeping the analog front end compact.
Recommended
Automotive Infotainment / Body Electronics (Non-Safety)
Body and infotainment modules (HVAC mixers, seat-position controllers, audio source select) often need 8 channels of analog monitoring tied to a 3.3 V or 5 V microcontroller. The MAX1091BEEI+T's 8 SE inputs, +3 V AVDD and VLOGIC up to +5.5 V make it a clean fit for non-safety automotive subsystems where AEC-Q100 is not required. Its automatic power-down and 2 µs wake-up keep quiescent current low during key-off, supporting automotive dark-current targets.
Recommended
Touch / Position Sensing Front Ends
Multi-channel resistive touch panels, slider controls and rotary position sensors rely on a muxed SAR ADC with predictable per-channel latency. The MAX1091BEEI+T scans 8 single-ended resistive channels at up to 250 ksps aggregate, with full-scale set by the internal +2.5 V reference and zero pipeline delay, which simplifies touch event timing. The QSOP-28 footprint keeps the analog front end under 30 mm², leaving room for the touch controller and ESD protection on the same PCB.
Recommended
Recommended Products Summary
Engineering reference data for MAX1091BEEI+T — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX1091BCEI+T | MAX1091ACEI+T | MAX1093BEEI+T | MAX1091BEEI+ | MAX1060BEEI+T |
|---|---|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 28-pin QSOP | 28-pin QSOP | 28-pin QSOP | 28-pin QSOP | 28-pin QSOP | 28-pin QSOP |
| Resolution | 10 bit | 10 bit | 10 bit | 10 bit | 10 bit | 10 bit |
| Sample Rate | 250 ksps | 250 ksps | 250 ksps | 250 ksps | 250 ksps | 200 ksps |
| Input Channels | 8 SE | 8 SE | 8 SE | 4 SE / 2 diff | 8 SE | 8 SE |
| Internal Reference | +2.5 V | +2.5 V (alt grade) | +2.5 V (alt grade) | +2.5 V | +2.5 V | +2.5 V |
| Interface | Byte-wide parallel | Byte-wide parallel | Byte-wide parallel | Byte-wide parallel | Byte-wide parallel | Byte-wide parallel |
| VLOGIC Range | +1.8 V to +5.5 V | +1.8 V to +5.5 V | +1.8 V to +5.5 V | +1.8 V to +5.5 V | +1.8 V to +5.5 V | +1.8 V to +5.5 V |
Key Differentiators
- Independent VLOGIC rail lets the ADC interface directly to 1.8 V-5.5 V hosts (vs MAX1060BEEI+T)
- 8 single-ended input channels in the same 28-pin QSOP footprint (vs MAX1093BEEI+T)
- Automatic hardware/software power-down with 2 µs wake-up (vs MAX1060BEEI+T)
Design Notes
Place a 0.1 µF ceramic decoupling capacitor as close as possible to each of the AVDD and VLOGIC pins, and add a 4.7 µF (or larger) tantalum/ceramic bulk capacitor on AVDD. Power AVDD from a clean, low-noise 3 V LDO rail - switching regulator ripple couples directly into the SAR comparator and degrades SNR. Keep the AVDD and VLOGIC traces short and star-ground the analog and digital grounds back at one point to avoid digital return currents polluting the reference.
Route the analog input traces (AIN0-AIN7) as short and as symmetric as possible, and guard them with a ground ring tied to AGND. Place the 4.7 µF REF bypass capacitor as close to the REF pin as the layout allows, with its ground return to AGND - not DGND. The QSOP-28 thermal pad (if exposed) should be soldered to a small copper pour on the AGND plane to keep the reference and input mux thermally stable.
Do not drive REF with a high-current external reference - the internal +2.5 V reference has limited drive capability and is intended as a low-current bias node. Avoid leaving unused analog inputs floating; tie them to mid-supply (or AGND through a defined resistor) so the input mux does not sample an undefined voltage. Finally, do not assume software power-down is automatic - the part requires an explicit write to the power-down bit (or a PD pin edge) to enter shutdown between conversions.
Estimated: with 250 ksps and a 4 MHz internal SAR clock, the parallel D0-D7 bus toggles every 250 ns during read-back. Place a small (~22-47 Ω) series resistor on each data line near the ADC to damp reflections when the bus is longer than ~50 mm, especially if the bus fans out to an FPGA. Keep CS and RD traces short and away from the analog input traces; the digital switching transients on RD can otherwise couple into the SAR comparator through the substrate and add 1-2 LSB of conversion noise.
Compliance Information
Per the Maxim product page, the MAX1091BEEI+T is supplied lead-free and RoHS compliant. REACH compliance is stated on Maxim's environmental information. The part is not AEC-Q100 qualified and is targeted at industrial and consumer applications, not automotive safety.
