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Analog Devices Inc./Maxim Integrated MAX494ESD
- Part No.:
- MAX494ESD
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX494ESD.pdf
- Description:
- IC OPAMP GP 4 CIRCUIT 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,213
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Product details
Overview
MAX494ESD from Maxim Integrated is a quad micropower operational amplifier with rail-to-rail input and output swing, operating from +2.7V to +6V single supply or ±1.35V to ±3V dual supplies. Each amplifier draws ≤150µA quiescent current, delivers 25nV/√Hz input voltage noise, supports 500kHz gain-bandwidth product, and drives 1kΩ loads - enabling precision signal conditioning in battery-powered portable instrumentation.
For engineers reviewing the MAX494ESD datasheet, MAX494ESD pinout, MAX494ESD application, or MAX494ESD equivalent, this page provides verified technical context, package mapping, real-world use cases, and validated alternative options for low-voltage, rail-to-rail op amp selection in space- and power-constrained designs.
Technical Context
The MAX494ESD integrates four independent precision op amps on a single die using a proprietary CMOS process optimized for micropower operation. Its input stage employs complementary NPN/PNP pairs to achieve rail-to-rail common-mode range (VEE − 0.25V to VCC + 0.25V), while the folded-cascode output stage enables rail-to-rail output swing within 50mV of rails under 100kΩ load.
Each amplifier features unity-gain stability, no phase reversal on overdriven inputs, and maintains ≥82dB CMRR and ≥86dB PSRR across −40°C to +85°C. The device drives capacitive loads >1nF without external compensation and exhibits <0.003% THD+N at 1kHz with 2Vp-p output into 10kΩ.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | +2.7V to +6V single supply or ±1.35V to ±3V dual supply - enables direct integration with Li-ion, coin-cell, and low-voltage logic systems. |
| Quiescent Current per Amp | ≤150µA at +25°C - allows continuous operation in multi-channel sensor front-ends with sub-600µA total system bias. |
| Input Offset Voltage | ±200µV max (TA = +25°C) - ensures <0.5 LSB error when buffering 12-bit ADCs like MAX187 with 4.096V reference. |
| Gain-Bandwidth Product | 500kHz - supports stable unity-gain buffering and low-frequency active filtering up to ~50kHz with adequate phase margin. |
| Input Voltage Noise Density | 25nV/√Hz at 1kHz - preserves SNR in high-impedance sensor interfaces such as thermocouple or pH electrode amplification. |
| Output Voltage Swing | Within 50mV of VEE and VCC with 100kΩ load - maximizes dynamic range in 3V systems, delivering >2.9Vp-p output from 3V supply. |
| Common-Mode Input Range | VEE − 0.25V to VCC + 0.25V - permits direct sensing of signals at or beyond supply rails without phase reversal or latchup. |
Pinout & Package
MAX494ESD is available in 14-pin SO (small-outline) package with industry-standard quad op amp pinout. Pin 1 is OUT1; pins 2–3 are IN1−/IN1+; pins 4–5 are IN2+/IN2−; pins 6–7 are OUT2/VEE; pins 8–9 are VCC/OUT3; pins 10–11 are IN3+/IN3−; pins 12–13 are IN4−/IN4+; pin 14 is OUT4. No internal connection at pin 11 for MAX494 variants per datasheet Figure 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | OUT1 | Amplifier 1 output - connects directly to downstream ADC input or filter network; rail-to-rail swing enables full-scale utilization. |
| 2 | IN1− | Inverting input of Amp 1 - matched impedance routing required to minimize offset error from input bias current mismatch. |
| 3 | IN1+ | Noninverting input of Amp 1 - accepts signals from VEE to VCC; internal protection diodes limit differential input to ±0.7V. |
| 4 | IN2+ | Noninverting input of Amp 2 - shares same rail-to-rail CMVR and low-noise characteristics as IN1+. |
| 5 | IN2− | Inverting input of Amp 2 - used in precision inverting configurations; requires R3 = R1∥R2 for bias current cancellation. |
| 6 | OUT2 | Amplifier 2 output - electrically isolated from OUT1; supports independent channel processing in multi-sensor systems. |
| 7 | VEE | Negative supply pin - tied to ground in single-supply mode; must be bypassed with 1µF + 0.1µF ceramic capacitor. |
| 8 | VCC | Positive supply pin - accepts +2.7V to +6V; decoupling reduces PSRR degradation at high frequencies. |
| 9 | OUT3 | Amplifier 3 output - enables three-channel simultaneous acquisition without external multiplexing. |
| 10 | IN3+ | Noninverting input of Amp 3 - identical electrical specs to IN1+/IN2+; supports common-mode signals up to VCC + 0.25V. |
| 12 | IN4− | Inverting input of Amp 4 - completes quad functionality; all four amps share same DC accuracy and AC performance. |
| 13 | IN4+ | Noninverting input of Amp 4 - enables fourth independent signal path; no internal connection at pin 11 per datasheet. |
| 14 | OUT4 | Amplifier 4 output - supports 4-channel data acquisition, differential pair buffering, or multi-stage filtering topologies. |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail input common-mode range | Extends 0.25V beyond VEE and VCC - eliminates need for level-shifting circuitry when interfacing with sensors operating near supply rails. |
| Rail-to-rail output swing | Reaches within 50mV of VEE/VCC under 100kΩ load - preserves >98% of available dynamic range in 3V systems. |
| No phase reversal on overdriven inputs | Guaranteed behavior beyond CMVR - prevents catastrophic output latching during transient overvoltage events in industrial I/O. |
| Drives >1nF capacitive loads | Stable with 1000pF pure capacitance (RL = ∞) - simplifies anti-aliasing filter design without isolation resistors in most applications. |
| 200µV max input offset voltage | Contributes <0.5 LSB error in 12-bit ADC systems - enables high-accuracy measurement without external trimming circuitry. |
| 150µA max supply current per amp | Enables 4-channel operation at <600µA total - extends battery life in portable medical monitors and handheld test equipment. |
Applications
| Portable ECG Monitor | Battery-Powered Data Logger |
|---|---|
|
Use Scenario: Amplifying microvolt-level biopotential signals from dry electrodes in a handheld ECG unit powered by two AAA cells. IC Role / Device Role / Timing Role: Quad amplifier configured as three instrumentation-stage buffers (Amp1–3) and one reference buffer (Amp4) for right-leg drive. Use Value: Rail-to-rail input enables direct coupling to electrode nodes at 0V–3V; 25nV/√Hz noise density preserves diagnostic SNR; 150µA/amp minimizes battery drain during 24-hour monitoring. |
Use Scenario: Conditioning analog outputs from temperature, humidity, and pressure sensors in an environmental logging node deployed for weeks on coin-cell power. IC Role / Device Role / Timing Role: Four independent channels condition each sensor's output prior to SAR ADC sampling at 100SPS. Use Value: 200µV offset ensures <±1°C error in RTD measurements; rail-to-rail output fully utilizes 3V ADC reference; 600µA total quiescent current enables >1-year battery life. |
| Low-Voltage Industrial Sensor Hub | Multi-Channel Precision ADC Front-End |
|
Use Scenario: Signal conditioning for 4-wire RTD, thermocouple, and strain gauge bridges in a DIN-rail mounted sensor interface module operating from 3.3V rail. IC Role / Device Role / Timing Role: All four amps used in programmable-gain instrumentation amplifier topology with external resistors and reference. Use Value: CMRR ≥82dB rejects common-mode noise from shared 3.3V supply; no phase reversal prevents output lockup during bridge imbalance transients; 500kHz GBW supports 10kHz anti-aliasing. |
Use Scenario: Driving four channels of MAX187 12-bit ADCs in a portable oscilloscope front-end requiring simultaneous sampling and low distortion. IC Role / Device Role / Timing Role: Each MAX494ESD amp buffers one ADC input with gain-of-two configuration referenced to 4.096V internal reference. Use Value: 0.003% THD+N ensures clean waveform capture; 200µV offset contributes <0.5 LSB error; rail-to-rail swing maximizes effective resolution across full 0–4.096V range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad rail-to-rail op amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLV2464IDR | Higher quiescent current (550µA/amp), wider supply range (2.7V–6V), lower offset (150µV typ), but only 600kHz GBW and no guaranteed phase reversal immunity. | Preferred where higher speed or lower offset is critical; unsuitable for ultra-low-power designs requiring <150µA/amp. | Select TLV2464IDR when bandwidth >500kHz is needed and power budget allows >2.2mA total quiescent current. |
| AD8604ARUZ | Lower noise (12nV/√Hz), lower offset (60µV max), but higher supply current (1mA/amp), narrower CMVR (to VCC − 0.1V), and no guaranteed rail-to-rail input beyond VCC. | Better for high-precision, low-noise applications with ample power; not suitable for input signals exceeding VCC − 0.1V. | Choose AD8604ARUZ for metrology-grade accuracy where supply current >4mA is acceptable and input stays within VEE to VCC − 0.1V. |
Compared with TLV2464IDR and AD8604ARUZ, MAX494ESD uniquely balances micropower operation (≤150µA/amp), guaranteed rail-to-rail input beyond supplies, and phase reversal immunity - making it optimal for battery-powered, robust-sensing applications where power, reliability, and rail compatibility are jointly constrained.
Availability
MAX494ESD is available at Aetrix Electronics and suitable for portable ECG monitors, battery-powered data loggers, and low-voltage industrial sensor hubs requiring stable component supply with long-term lifecycle support.
Supply support for MAX494ESD includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Maxim Integrated (now part of Analog Devices) designs precision analog and mixed-signal ICs for demanding industrial, medical, and communications applications.
The MAX492/MAX494/MAX495 family was engineered specifically for micropower, rail-to-rail signal conditioning in battery-operated equipment - prioritizing ultra-low supply current, wide input/output dynamic range, and robustness against overvoltage conditions.
FAQ
What is the maximum capacitive load the MAX494ESD can drive without oscillation?
The MAX494ESD remains stable driving up to 1000pF with no load resistance (RL = ∞) and up to 400pF while sourcing ~100µA. Stability improves when sinking current or adding a small series isolation resistor (e.g., 47Ω) at the output. For 10,000pF loads, a 47Ω resistor restores stability per Figure 9b in the datasheet. This capability eliminates external compensation in most anti-aliasing filter designs.
Does the MAX494ESD support true rail-to-rail input common-mode voltage?
Yes - the MAX494ESD guarantees rail-to-rail input common-mode range from VEE − 0.25V to VCC + 0.25V across its full operating temperature range. Unlike many rail-to-rail op amps, it also prevents phase reversal or latchup even when inputs exceed this range, making it suitable for direct interfacing with sensors whose outputs may transiently go beyond supply rails.
Is external offset nulling possible on the MAX494ESD?
No - external offset nulling via NULL pins is only supported on the single MAX495 variant (pins 1 and 5). The MAX494ESD does not provide NULL pins or internal offset trim capability. Its ±200µV max input offset voltage at +25°C is factory-trimmed and remains stable over temperature (±2µV/°C tempco), eliminating need for field adjustment in most precision applications.
What is the typical power-up settling time for the MAX494ESD?
When powered from 0V to VCC, the MAX494ESD output settles to final value in approximately 4µs for VCC = +3V and 10µs for VCC = +5V, assuming noninverting input held at mid-supply (VCC/2) in voltage-follower configuration. This fast settling enables rapid wake-up from sleep modes in battery-powered systems without sacrificing measurement accuracy.
Can the MAX494ESD operate from split supplies?
Yes - the MAX494ESD supports dual supplies from ±1.35V to ±3V. In split-supply mode, VEE connects to the negative rail (e.g., −1.5V) and VCC to the positive rail (e.g., +1.5V), maintaining the same rail-to-rail input/output performance and 150µA/amp quiescent current. Bypass capacitors must be placed from each supply to ground.
MAX494ESD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Amplifier Type:
- General Purpose
- Number of Circuits:
- 4
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 0.2V/µs
- Gain Bandwidth Product:
- 500 kHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 25 nA
- Voltage - Input Offset:
- 200 µV
- Current - Supply:
- 150µA (x4 Channels)
- Current - Output / Channel:
- 30 mA
- Voltage - Supply Span (Min):
- 2.7 V
- Voltage - Supply Span (Max):
- 6 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
MAX494ESD FAQ
1.How can I place an order for MAX494ESD through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX494ESD on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MAX494ESD reliable?
The price and inventory of MAX494ESD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX494ESD is usually 5 days.
3.What payment methods are accepted for MAX494ESD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX494ESD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX494ESD?
MAX494ESD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX494ESD order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MAX494ESD?
For technical support, including MAX494ESD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX494ESD requirements.
6.How does Aetrix verify that MAX494ESD is sourced from the original manufacturer or authorized distributors?
All MAX494ESD products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MAX494ESD meets industry standards.
7.What is the process for return or replacement of MAX494ESD?
All MAX494ESD units undergo pre-shipment inspection (PSI). If there is an issue with MAX494ESD, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MAX494ESD part is unused and in its original packaging.
Return procedure for MAX494ESD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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