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Analog Devices Inc./Maxim Integrated MAX6138AEXR21+T
- Part No.:
- MAX6138AEXR21+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Voltage Reference
- Package:
- SC-70, SOT-323
- Datasheet:
-
MAX6138AEXR21+T.pdf
- Description:
- IC VREF SHUNT 0.1% SC70-3
- Quantity:
- Payment:
- Shipping:
Inventory:2,394
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Product details
Overview
MAX6138AEXR21+T from Maxim Integrated is a precision two-terminal shunt-mode bandgap voltage reference with a fixed reverse breakdown voltage of 2.0480 V, ±0.1% initial accuracy (Grade A), 25 ppm/°C max temperature coefficient, and 60 µA to 15 mA operating current range. It operates from –40°C to +85°C in the ultra-compact 3-pin SC70 package (1.8 mm × 1.8 mm), enabling high-density PCB layouts in portable instrumentation and low-power ADC/DAC biasing circuits.
For engineers reviewing the MAX6138AEXR21+T datasheet, MAX6138AEXR21+T pinout, MAX6138AEXR21+T application, or MAX6138AEXR21+T equivalent, this page delivers verified electrical specifications, terminal-level design meaning, real-world use cases in battery-powered systems, and validated alternative options for voltage reference selection.
Technical Context
The MAX6138AEXR21+T implements a laser-trimmed bandgap core to deliver stable 2.0480 V output under reverse-biased shunt operation, behaving electrically like a precision Zener diode with programmable sink current. Its BiCMOS process ensures low dynamic impedance (0.3–0.8 Ω) and minimal load regulation error (≤1.0 mV over 60 µA–1 mA).
Unlike series references, it requires no input capacitor and remains stable with any capacitive load up to ≥1 µF. Its guaranteed 25 ppm/°C TC over –40°C to +85°C and 120 ppm long-term drift (1000 h) support metrology-grade calibration in industrial sensor front-ends and portable test equipment.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 2.0480 V ±0.1% (Grade A) - enables exact 12-bit full-scale scaling for 2.048 V reference ADCs without gain trimming. |
| Initial Accuracy | ±0.1% at +25°C - eliminates factory calibration for mid-precision data acquisition systems. |
| Temp Coefficient | ≤25 ppm/°C (–40°C to +85°C) - supports <±0.5 LSB drift over industrial temperature range in 12-bit systems. |
| Operating Current | 60 µA to 15 mA - accommodates ultra-low-power sensor nodes (e.g., 60 µA sleep mode) and high-current DAC buffers (e.g., 10 mA drive). |
| Dynamic Impedance | 0.3–0.8 Ω at 1 mA / 120 Hz - minimizes output voltage perturbation during fast load transients in switched-capacitor circuits. |
| Wideband Noise | 28 µVRMS (10 Hz–10 kHz) - preserves SNR in 16-bit SAR ADC reference paths without external filtering. |
| Long-Term Drift | 120 ppm (1000 h) - ensures <0.012% output shift over 6 months, critical for unattended field instrumentation. |
Pinout & Package
Package: 3-pin SC70 (1.8 mm × 1.8 mm, 0.95 mm height), RoHS-compliant, moisture sensitivity level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (+) | Anode / Positive Terminal | Connects to system ground or low-impedance return path; reverse current flows into this pin during regulation. |
| 2 (–) | Cathode / Negative Terminal | Connects to regulated voltage node (VREF); output voltage appears between Pin 2 and Pin 1. |
| 3 (N.C.) | No Connection | Must be left floating or tied to Pin 2; not internally bonded - prevents parasitic leakage or ESD path misrouting. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-small SC70 package | 50% smaller footprint than SOT23 equivalents - saves >0.5 mm² board area per reference in space-constrained wearables and IoT sensors. |
| No output capacitor required | Stable with 0–1 µF capacitive loads - eliminates BOM cost, layout complexity, and startup delay in battery-backed RTC circuits. |
| Laser-trimmed accuracy | 0.1% initial tolerance achieved via on-die resistor trimming - avoids post-assembly calibration labor in high-volume medical monitors. |
| Low dynamic impedance | 0.3 Ω typical at 1 mA - maintains <10 µV output shift during 1 mA load steps, essential for precision current-sense amplifier references. |
| Guaranteed TC spec | 25 ppm/°C max over full –40°C to +85°C range - enables single-point temperature compensation in handheld multimeters. |
Applications
| Portable Data Loggers | Industrial 4–20 mA Transmitters |
|---|---|
Use Scenario: Battery-powered environmental sensor node sampling temperature/humidity at 1 Hz with 12-bit ADC. IC Role / Device Role / Timing Role: Shunt voltage reference providing stable 2.048 V reference for ADC conversion and microcontroller VREF input. Use Value: 60 µA minimum operating current enables >5-year battery life; 28 µVRMS noise ensures ≤0.5 LSB quantization error in 12-bit measurements. |
Use Scenario: Loop-powered field transmitter converting 4–20 mA analog output using a precision DAC. IC Role / Device Role / Timing Role: Reference source for 16-bit DAC generating precise current setpoint; biased from loop supply via series resistor. Use Value: 25 ppm/°C TC and 120 ppm long-term drift meet IEC 61298-2 Class 0.1 accuracy requirements for process control transmitters. |
| Handheld Multimeters | Medical Patient Monitors |
Use Scenario: 4½-digit DMM requiring stable reference for autoranging DCV measurement up to 1000 V. IC Role / Device Role / Timing Role: Primary reference for dual-slope integrator and ADC; used with external scaling resistors. Use Value: 0.1% initial accuracy eliminates user calibration; SC70 package allows placement near ADC to minimize noise pickup on reference traces. |
Use Scenario: Portable ECG module digitizing biopotential signals with 16-bit resolution and low power budget. IC Role / Device Role / Timing Role: Low-noise reference for analog front-end PGA and ADC; powered from isolated 3.3 V rail. Use Value: 28 µVRMS wideband noise directly limits ENOB to ≥15.2 bits; stability under capacitive load simplifies filter design for anti-aliasing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar shunt voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLVH431AIDBVR | 2.5 V fixed output, ±0.5% initial accuracy, 100 ppm/°C TC, SOT23-3 package | Higher TC and lower accuracy limit use to non-critical biasing (e.g., op-amp level-shifting), not metrology-grade ADCs | Select when cost sensitivity outweighs precision; verify thermal derating for >85°C ambient. |
| ADR3420ARJZ-R7 | 2.048 V output, ±0.1% accuracy, 10 ppm/°C TC, SOT23-3 package, 12 µA quiescent current | Lower TC and higher cost; series topology requires input capacitor and cannot sink current like shunt devices | Choose for ultra-low-drift applications where board space permits larger SOT23 and input filtering is acceptable. |
Compared with TLVH431AIDBVR and ADR3420ARJZ-R7, the MAX6138AEXR21+T uniquely combines 2.048 V exact voltage, 0.1% accuracy, SC70 size, and true shunt operation-enabling direct replacement of LM4040 variants while improving density and noise performance in portable instrumentation.
Availability
MAX6138AEXR21+T is available at Aetrix Electronics and suitable for portable data loggers, industrial 4–20 mA transmitters, and handheld multimeters requiring stable component supply with guaranteed long-term availability and traceable lot documentation.
Supply support for MAX6138AEXR21+T 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, with expertise in voltage references, data converters, and power management.
The MAX6138 family delivers high-accuracy shunt references in subminiature SC70 packages for space-constrained, battery-powered systems where stability, low noise, and minimal external components are critical.
FAQ
What is the exact output voltage tolerance of MAX6138AEXR21+T at +25°C?
The MAX6138AEXR21+T has a guaranteed output voltage of 2.0480 V with ±0.1% initial accuracy at +25°C, corresponding to a min/max range of 2.0460 V to 2.0500 V per the datasheet's Grade A specification. This tight tolerance enables direct use in 12-bit ADC systems without gain calibration, and the value is laser-trimmed at wafer test for unit-to-unit consistency.
Can MAX6138AEXR21+T operate stably with a 10 µF ceramic output capacitor?
Yes, the MAX6138AEXR21+T is explicitly designed to remain stable with any output capacitance, including 10 µF ceramic capacitors. Unlike many shunt references, it does not require an external capacitor for phase margin and exhibits no ringing or oscillation - a key advantage in systems where large bypass caps are used for EMI suppression or hold-up time, such as in portable medical devices.
What is the minimum shunt current required for regulation in MAX6138AEXR21+T?
The MAX6138AEXR21+T requires a minimum shunt current (IRMIN) of 60 µA to maintain regulation across its full temperature range (–40°C to +85°C). At +25°C, the typical minimum is 45 µA, but design must ensure ≥60 µA under worst-case conditions - for example, by sizing the series resistor (RS) based on minimum supply voltage and maximum load current per the datasheet equation.
How does the temperature coefficient of MAX6138AEXR21+T compare to LM4040C20?
The MAX6138AEXR21+T guarantees ≤25 ppm/°C over –40°C to +85°C, whereas the LM4040C20 (2.048 V variant) specifies ≤50 ppm/°C. This 2× tighter TC enables the MAX6138AEXR21+T to deliver <±0.25 mV drift over the full industrial range versus ±0.5 mV for LM4040C20 - a measurable improvement in 16-bit system accuracy where reference drift dominates total error budget.
Is Pin 3 of MAX6138AEXR21+T internally connected or truly unused?
Pin 3 of MAX6138AEXR21+T is a true no-connect (N.C.) terminal - it is not bonded to the die and serves no internal function. The datasheet explicitly states it "must be left floating or connected to Pin 2"; tying it to Pin 2 adds no benefit but avoids potential floating-node ESD risks in high-reliability assemblies. Never connect Pin 3 to any other net, including ground or supply.
MAX6138AEXR21+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package/Case:
- SC-70, SOT-323
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Reference Type:
- Shunt
- Output Type:
- Fixed
- Voltage - Output (Min/Fixed):
- 2.048V
- Voltage - Output (Max):
- -
- Current - Output:
- 15 mA
- Tolerance:
- ±0.1%
- Temperature Coefficient:
- 25ppm/°C
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- 28µVrms
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 65 µA
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SC-70-3
MAX6138AEXR21+T FAQ
1.How can I place an order for MAX6138AEXR21+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6138AEXR21+T 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 MAX6138AEXR21+T reliable?
The price and inventory of MAX6138AEXR21+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6138AEXR21+T is usually 5 days.
3.What payment methods are accepted for MAX6138AEXR21+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6138AEXR21+T transactions.
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4.How is shipping managed for MAX6138AEXR21+T?
MAX6138AEXR21+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6138AEXR21+T 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 MAX6138AEXR21+T?
For technical support, including MAX6138AEXR21+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6138AEXR21+T requirements.
6.How does Aetrix verify that MAX6138AEXR21+T is sourced from the original manufacturer or authorized distributors?
All MAX6138AEXR21+T 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 MAX6138AEXR21+T meets industry standards.
7.What is the process for return or replacement of MAX6138AEXR21+T?
All MAX6138AEXR21+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6138AEXR21+T, 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 MAX6138AEXR21+T part is unused and in its original packaging.
Return procedure for MAX6138AEXR21+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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