NATIONAL SEMICONDUCTOR LM4121 User's Manual
Summary
The LM4121 is a precision micropower, low dropout voltage reference designed for reliable power in demanding environments. This manual details its technical specifications, covering ultra-low supply current (160 µA typ.), high accuracy, and guaranteed performance across extreme temperature ranges (−40°C to +85°C or up to +125°C). Available in both fixed 1.25V and adjustable versions, this component is ideally suited for battery-powered, portable medical, instrumentation, and industrial equipment that requires highly precise voltage regulation with exceptional power efficiency.
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LM recision icropow er Low ropout Voltage eference
LM4121 Precision Micropower Low Dropout Voltage Reference General Description Features (LM4121-1.2)
The LM4121 is precision bandgap voltage reference avail- Small SOT23-5 package
able in fixed 1.25V and adjustable version with up to m A Low voltage operation current source and sink capability. High output voltage accuracy: 0.2%
This series reference operates with input voltages as low as Source and Sink current output: ±5 m A
1.8V and up to 12V consuming µA (Typ.) supply current. Supply current: µA Typ. In power down mode, device current drops to less than µA.
Low Temperature Coefficient: ppm/˚C
The LM4121 comes in two grades and Standard. The best Enable pin grade devices (A) have an initial accuracy of 0.2%, while the
Output voltages: 1.25V and Adjustable
standard have an initial accuracy of 0.5%, both with
Industrial temperature Range: −40˚C to +85˚C
tempco of 50ppm/˚C guaranteed from −40˚C to +125˚C.
(For extended temperature range, −40˚C to 125˚C,
The very low operating voltage, low supply current and
contact National Semiconductor)
power-down capability of the LM4121 makes this product an ideal choice for battery powered and portable applications.
Applications
The device performance is guaranteed over the industrial
Portable, battery powered equipment
temperature range (−40˚C to +85˚C), while certain specs are
Instrumentation and process control
guaranteed over the extended temperature range (−40˚C to
Automotive Industrial
+125˚C). Please contact National for full specifications over
the extended temperature range. The LM4121 is available in Test equipment
standard 5-pin SOT-23 package. Data acquisition systems
Precision regulators Battery chargers stations Communications Medical equipment
Block Diagram Connection Diagrams
DS101291-2
Refer to the Ordering Information Table in this Data Sheet for Specific Part Number
SOT23-5 Surface Mount Package
DS101291-1
Resistors are removed on the LM4121-ADJ †LM4121-ADJ only
LM4121-1.2 Block Diagram
DS101291-35
National Semiconductor Corporation DS101291 www.national.com
Page Summary Contents For NATIONAL SEMICONDUCTOR LM4121 User's Manual
Manual Details
| Brand | National |
|---|---|
| Pages | 16 |
| File Size | 436.33 KB |
| Published | June 15, 2026 |
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Frequently Asked Questions
What is the current consumption in power-down mode?
In power down mode, the device current can drop to less than 2 μA.
What common voltage reference output levels are available?
The LM4121 is available in a fixed 1.25V or an adjustable version with up to 5 mA sink/source capability.
What temperature range does the standard device support?
It supports an industrial temperature range of −40˚C to +85˚C, and extended grades can reach +125˚C.
How do I choose between accuracy grades A and Standard?
The Grade 'A' devices offer a superior initial accuracy of 0.2%, while standard grade devices have an initial accuracy of 0.5%.