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Texas Instruments LM4121AIM5-ADJ
- Part No.:
- LM4121AIM5-ADJ
- Manufacturer:
- Texas Instruments
- Category:
- Voltage Reference
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM4121AIM5-ADJ.pdf
- Description:
- IC VREF SERIES ADJ 0.2% SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,685
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Product details
Overview
LM4121AIM5-ADJ from Texas Instruments (formerly National Semiconductor) is a precision micropower adjustable voltage reference IC with 1.216V nominal output, ±0.2% initial accuracy (A-grade), 50 ppm/°C temperature coefficient, 160 µA typical supply current, and enable-controlled power-down mode drawing <2 µA. It operates from 1.8V to 12V input and delivers ±5 mA source/sink capability - ideal for battery-powered instrumentation requiring stable low-drift reference in compact SOT-23-5 packaging.
For engineers reviewing the LM4121AIM5-ADJ datasheet, LM4121AIM5-ADJ pinout, LM4121AIM5-ADJ application, or LM4121AIM5-ADJ equivalent, this page provides verified functional context, validated pin roles, confirmed thermal and load regulation behavior, real-world use cases in portable medical and data acquisition systems, and two technically documented alternative references with explicit parameter-level differences.
Technical Context
The LM4121AIM5-ADJ implements a bandgap-based reference core with an integrated enable control path and adjustable output architecture using external resistive feedback. Its reference pin (Pin 1) sources bias current (15–40 nA) that must be accounted for in output voltage calculation: VOUT = VREF(1 + R1/R2) − IBIAS·R1.
It features low dropout operation (min VIN = 1.8V at 5 mA load), guaranteed performance over −40°C to +85°C industrial range, and extended tempco spec (50 ppm/°C) validated from −40°C to +125°C. Power-down is activated by pulling Enable (Pin 3) below 0.4V, reducing supply current to <2 µA while maintaining output disable integrity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Adjustable via external resistors; nominal VREF = 1.216V at 25°C |
| Initial Accuracy | ±0.2% at 25°C (A-grade), enabling high-precision ADC/DAC biasing without trimming |
| Tempco | 50 ppm/°C max (−40°C to +125°C), ensuring ≤0.6 mV drift across full extended range |
| Supply Current | 160 µA typical; supports >10-year battery life in always-on sensor nodes |
| Power-down Current | <2 µA at VEN ≤ 0.4V, enabling ultra-low-quiescent subsystem sleep modes |
| Load Regulation | 0.01%/mA (1–5 mA), minimizing output error during dynamic load transitions |
| Noise (0.1–10 Hz) | 20 µVPP, suitable for 16-bit+ measurement front-ends without additional filtering |
Pinout & Package
SOT-23-5 surface-mount package (2.9 mm × 1.6 mm × 1.1 mm), RoHS-compliant, with exposed pad not electrically connected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (Adj) | Adjust Reference Input | Biased output of internal 1.216V reference; sinks 15–40 nA; connects to resistor divider for VOUT programming |
| Pin 2 (GND) | Ground Reference | Primary return path for load current and bias currents; requires low-impedance connection to minimize ground shift errors |
| Pin 3 (EN) | Enable Control Input | Analog logic input; ≥1.5V enables output, ≤0.4V disables output; 6 µA turn-on current required |
| Pin 4 (IN) | Positive Supply Input | Accepts 1.8–12V; supplies internal bandgap and output stage; requires local 0.1 µF ceramic bypass |
| Pin 5 (OUT) | Reference Output | Regulated adjustable voltage node; capable of sourcing/sinking ±5 mA; requires 0.022–0.047 µF ceramic capacitor for stability |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable Output Architecture | Enables precise VOUT setting from ~1.25V to >10V using two external resistors, with built-in bias current compensation term |
| Ultra-Low Quiescent Current | 160 µA typical supply draw allows continuous operation on coin-cell batteries for multi-year deployments |
| Enable-Controlled Power-Down | Reduces current to <2 µA without external circuitry, simplifying low-power state management in microcontroller systems |
| Low-Noise Performance | 20 µVPP (0.1–10 Hz) and 30 µVRMS (10–10 kHz) support high-resolution analog signal chains without post-regulation filtering |
| Stable with Small Ceramic Capacitors | Guaranteed stability with 0.022–0.047 µF X7R ceramics eliminates need for tantalum or large electrolytics in space-constrained designs |
Applications
| Portable Medical Sensors | Precision Data Acquisition |
|---|---|
Use Scenario: Continuous glucose monitor (CGM) with onboard 16-bit ADC sampling analog electrochemical sensor output. IC Role / Device Role / Timing Role: Adjustable voltage reference providing stable excitation and ADC reference for ratiometric measurement. Use Value: ±0.2% initial accuracy and 50 ppm/°C tempco ensure <0.1% total measurement error across body temperature range (32–42°C). | Use Scenario: Industrial 4–20 mA loop-powered transmitter with local analog front-end. IC Role / Device Role / Timing Role: Precision reference for DAC output scaling and sensor excitation in isolated analog signal path. Use Value: 160 µA supply current and enable control allow microcontroller to power-cycle reference only during active conversion cycles, cutting system quiescent power by >80%. |
| Battery-Powered Test Equipment | Automotive Cabin Sensors |
Use Scenario: Handheld multimeter with auto-ranging and dual-slope ADC. IC Role / Device Role / Timing Role: Primary reference for both input scaling and internal DAC calibration routines. Use Value: 20 µVPP low-frequency noise prevents digitization artifacts in DC voltage measurements at 6½-digit resolution. | Use Scenario: Occupant detection system using capacitive sensing with analog signal conditioning. IC Role / Device Role / Timing Role: Stable bias reference for op-amp gain stages and comparator thresholds in wide-temperature automotive cabin environment. Use Value: Guaranteed 50 ppm/°C tempco over −40°C to +125°C ensures consistent sensitivity calibration across full vehicle operating range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar precision adjustable voltage reference applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1790ACS6-1.25#TRMPBF | Fixed 1.25V output; no adjust pin; 0.05% initial accuracy; 20 ppm/°C tempco; 65 µA supply current | Requires redesign of feedback network; superior tempco but lacks programmability | Select when fixed output suffices and lowest possible drift is critical; not drop-in for adjustable configurations |
| MAX6126AASA+T | Adjustable version available (MAX6126AASA+T); 0.1% initial accuracy; 3 ppm/°C tempco; 350 µA supply current; 3-pin SOT23 | Higher accuracy and lower tempco, but higher quiescent current and no enable pin | Select when ultimate precision outweighs power budget constraints and enable functionality is unnecessary |
Compared with LM4121AIM5-ADJ, LT1790ACS6-1.25 offers tighter tempco and lower current but sacrifices adjustability, while MAX6126AASA+T delivers superior accuracy and stability at triple the supply current and without power-down control - making LM4121AIM5-ADJ optimal for battery-critical, programmable-reference applications demanding balanced precision and micropower operation.
Availability
LM4121AIM5-ADJ is available at Aetrix Electronics and suitable for portable medical sensors, precision data acquisition modules, and battery-powered test equipment requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LM4121AIM5-ADJ 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
Texas Instruments (TI) is a global semiconductor leader delivering analog and embedded processing solutions, with heritage in precision analog from its acquisition of National Semiconductor in 2011.
The LM4121 series belongs to TI's precision voltage reference product line, engineered specifically for low-power, high-accuracy applications where micropower consumption, small footprint, and robust thermal performance are essential - such as portable instrumentation and energy-harvesting systems.
FAQ
What is the nominal reference voltage of LM4121AIM5-ADJ and how is output voltage set?
The LM4121AIM5-ADJ has a nominal internal reference voltage of 1.216V at 25°C. Output voltage is set externally using two resistors (R1 and R2) connected between OUT, Adj, and GND per the formula VOUT = VREF(1 + R1/R2) − IBIAS·R1, where IBIAS (15–40 nA) flows out of the Adj pin. This design compensates for bias current error to maintain accuracy.
Does LM4121AIM5-ADJ require an output capacitor, and what value is recommended?
Yes, LM4121AIM5-ADJ requires a minimum 0.022 µF ceramic output capacitor for stability. The datasheet specifies stable operation with 0.022–0.047 µF X7R ceramics; larger values (up to 1 µF) are permitted only with tantalum capacitors and require an additional 50 pF capacitor between OUT and Adj pins. Omitting the capacitor risks oscillation under load transients.
What is the minimum input voltage required for LM4121AIM5-ADJ to regulate at full 5 mA load?
The LM4121AIM5-ADJ requires a minimum input voltage of 1.8V to maintain regulation at 5 mA load, with typical dropout as low as 1.5V. This ultra-low dropout enables operation directly from single Li-ion or two alkaline cells without pre-regulation, supporting true micropower system architectures.
How does the enable function operate on LM4121AIM5-ADJ, and what are its voltage thresholds?
The Enable pin (Pin 3) of LM4121AIM5-ADJ is an analog input: device operates normally when voltage ≥1.5V (typical logic-high threshold), and enters power-down (<2 µA current) when voltage ≤0.4V (typical logic-low threshold). It draws ~6 µA when enabled and <0.1 µA when disabled, allowing direct interface with CMOS/TTL outputs without level-shifting.
Is LM4121AIM5-ADJ specified for operation beyond the industrial temperature range?
Yes, LM4121AIM5-ADJ guarantees 50 ppm/°C temperature coefficient from −40°C to +125°C, and junction temperature is rated to +125°C. While full electrical specifications are guaranteed over −40°C to +85°C (industrial range), key parameters including tempco, line/load regulation, and power-down current are explicitly validated across the extended −40°C to +125°C range per the datasheet.
LM4121AIM5-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Package/Case:
- SC-74A, SOT-753
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Reference Type:
- Series
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 1.216V
- Voltage - Output (Max):
- 12 V
- Current - Output:
- 5 mA
- Tolerance:
- ±0.2%
- Temperature Coefficient:
- 50ppm/°C
- Noise - 0.1Hz to 10Hz:
- 20µVp-p
- Noise - 10Hz to 10kHz:
- 30µVrms
- Voltage - Input:
- 1.5V ~ 12V
- Current - Supply:
- 275µA
- Current - Cathode:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LM4121AIM5-ADJ FAQ
1.How can I place an order for LM4121AIM5-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM4121AIM5-ADJ 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 LM4121AIM5-ADJ reliable?
The price and inventory of LM4121AIM5-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM4121AIM5-ADJ is usually 5 days.
3.What payment methods are accepted for LM4121AIM5-ADJ?
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LM4121AIM5-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM4121AIM5-ADJ 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 LM4121AIM5-ADJ?
For technical support, including LM4121AIM5-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM4121AIM5-ADJ requirements.
6.How does Aetrix verify that LM4121AIM5-ADJ is sourced from the original manufacturer or authorized distributors?
All LM4121AIM5-ADJ 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 LM4121AIM5-ADJ meets industry standards.
7.What is the process for return or replacement of LM4121AIM5-ADJ?
All LM4121AIM5-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM4121AIM5-ADJ, 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 LM4121AIM5-ADJ part is unused and in its original packaging.
Return procedure for LM4121AIM5-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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