AMS1117-3.3 and LM1117-3.3 are widely used 3.3V linear voltage regulators for embedded electronics, development boards, industrial control systems, communication equipment, and other power management applications.
Both belong to the popular 1117 family of low-dropout regulators and are commonly considered when designing a 3.3V power rail. However, the similarity in their part numbers does not mean that every electrical specification is identical.
For engineers comparing AMS1117-3.3 vs LM1117-3.3, the important factors include output voltage, load current, dropout voltage, input voltage, package, thermal performance, output capacitor requirements, and the exact manufacturer part number.
AMS1117-3.3 is a fixed-output 3.3V LDO regulator designed to convert a higher input voltage into a regulated 3.3V supply.
It is widely used in circuits where a simple linear regulator is required for powering microcontrollers, sensors, communication modules, memory devices, and other low-voltage electronics.
The 3.3V output version is particularly common because 3.3V is widely used by modern digital ICs and embedded processors.
Typical applications include:
Microcontroller boards
FPGA systems
IoT devices
Sensor modules
Communication circuits
Industrial controllers
Embedded electronic equipment
LM1117-3.3 is the fixed 3.3V version of Texas Instruments' LM1117 low-dropout linear regulator family.
TI specifies the LM1117 as an 800mA, 15V linear voltage regulator. The family includes fixed 1.8V, 2.5V, 3.3V and 5V versions as well as an adjustable version.
For example, TI's LM1117-3.3 ordering variants are available in packages such as TO-220 and TO-252, while other package options are also available within the family.
The device includes current limiting and thermal shutdown, making it suitable for general-purpose power regulation applications.
The main purpose of both devices in this comparison is to provide a regulated 3.3V output.
A 3.3V LDO can be used to supply:
MCUs
FPGAs
EEPROMs
Sensors
Wireless modules
Logic circuits
Display controllers
Peripheral ICs
The actual output-voltage accuracy depends on the exact device and operating conditions.
For LM1117-3.3, TI specifies a nominal 3.3V output. Its datasheet gives a 3.267V to 3.333V range under the specified test condition at 25°C, while the broader electrical characteristics specify the relevant limits across operating conditions.
For AMS1117-3.3, engineers should use the datasheet for the exact manufacturer and ordering code because specifications can vary among different 1117 implementations.
Output current is an important factor when selecting an LDO.
TI specifies the LM1117 family for up to 800mA of output current.
This makes LM1117-3.3 suitable for many embedded boards and moderate-current 3.3V power rails.
For AMS1117-3.3, the commonly published device specifications also position the device in the approximately 1A-class 1117 regulator category, but engineers should not assume that every AMS1117-branded device provides identical current capability.
The actual load requirement should always be compared with the maximum rated output current, thermal conditions, input voltage, and package.
Dropout voltage is one of the most important specifications for an LDO.
It determines how close the input voltage can approach the required output voltage before regulation is lost.
TI specifies a typical LM1117 dropout voltage of approximately 1.2V at 800mA.
This means that an LM1117-3.3 generally requires substantially more than 3.3V at its input when operating near its maximum load.
For example, when designing a 3.3V rail, engineers should not assume that a 3.5V input will always be sufficient at high current.
The actual dropout voltage varies with output current and operating conditions, so the relevant datasheet curves should be reviewed during power-supply design.
The input voltage must be high enough to maintain the required 3.3V output while remaining within the regulator's maximum input rating.
TI specifies the LM1117 family with a maximum input voltage of 15V and a minimum input voltage of 2.6V at the product level, with the actual fixed-output operating conditions depending on the selected version.
For an LM1117-3.3 circuit, the input voltage must therefore be selected with both dropout voltage and maximum input voltage in mind.
A higher input voltage can increase power dissipation because the regulator converts the voltage difference into heat.
Linear regulators dissipate excess voltage as heat.
The approximate power dissipation can be understood as:
P ≈ (VIN − VOUT) × IOUT
For a 5V input, 3.3V output and 500mA load, for example, the regulator must dissipate approximately 0.85W.
This can become significant for small PCB packages.
For this reason, engineers comparing AMS1117-3.3 and LM1117-3.3 should consider:
Input voltage
Output voltage
Load current
Package
PCB copper area
Ambient temperature
Thermal resistance
Maximum junction temperature
A regulator that meets the electrical current specification may still require additional thermal consideration in the actual product.
The LM1117 family is available in several packages.
TI lists options including:
SOT-223
TO-220
TO-252
TO-263
WSON
This provides flexibility when selecting the regulator for different PCB designs.
The package is particularly important when replacing an existing 1117 regulator because the same output voltage does not guarantee physical compatibility.
Engineers should compare:
Package dimensions
Pin numbering
Pin functions
PCB footprint
Thermal pad requirements
Copper area
Before replacing the component, the complete ordering code should be identified.
AMS1117-3.3 devices are commonly found in SOT-223 packages and other 1117-style package configurations.
However, different manufacturers may use different package options and markings.
For an existing PCB, engineers should never select a replacement only by searching for "1117 3.3V."
The complete part number should be compared with the original device to confirm:
Input pin
Ground pin
Output pin
Tab function
Thermal characteristics
This is especially important for SOT-223-based designs.
The output capacitor is important for LDO stability and transient response.
TI specifies a minimum 10µF load capacitance for LM1117 and notes that a 10µF tantalum capacitor is required at the output to improve transient response and stability.
When evaluating AMS1117-3.3 as an LM1117-3.3 alternative, engineers should check the capacitor requirements in the exact AMS1117 datasheet.
The capacitor's capacitance, ESR, voltage rating, temperature characteristics, and PCB placement can all influence regulator performance.
The LM1117 includes current limiting and thermal shutdown functions.
These protections help prevent damage when the regulator experiences excessive current or temperature.
The exact protection behavior varies by device family and manufacturer, so AMS1117-3.3 and LM1117-3.3 should be evaluated using their respective specifications rather than assuming that all 1117 devices provide identical protection thresholds.
Both types of 3.3V LDO can be used in a wide range of electronic designs.
A 3.3V LDO can provide power to microcontrollers and their peripheral circuits.
Applications include:
STM32 systems
ARM microcontroller boards
IoT controllers
Industrial control boards
Embedded systems
3.3V rails are commonly required by FPGA I/O banks and supporting digital logic.
An LDO can be used to generate a regulated rail from a higher input voltage when the current and thermal requirements are suitable.
Many sensors, wireless modules and interface ICs operate from 3.3V.
A 1117 regulator can provide a simple power source for these circuits when efficiency requirements are not particularly demanding.
1117-family regulators are frequently found on development boards because they provide a simple and inexpensive method of generating a 3.3V supply.
In many applications, AMS1117-3.3 can be evaluated as an alternative to LM1117-3.3 because both are 3.3V members of the 1117 LDO regulator family.
However, engineers should not treat them as automatically identical.
Before replacement, compare:
Maximum output current
Dropout voltage
Input voltage range
Output capacitor requirements
Load regulation
Line regulation
Quiescent current
Thermal protection
Current limiting
Pinout
Operating temperature
The exact manufacturer's datasheet should be used for the final replacement decision.
The same evaluation process applies in the opposite direction.
LM1117-3.3 may be suitable for a circuit currently using AMS1117-3.3 if its electrical and thermal specifications meet the system requirements.
However, engineers should pay particular attention to the regulator's dropout voltage.
If the original circuit has a small difference between input and output voltage, a regulator with a higher dropout voltage may fail to maintain the required 3.3V output at higher load currents.
Package compatibility must also be confirmed before making a PCB-level replacement.
One common application is converting a 5V rail to 3.3V.
Both AMS1117-3.3 and LM1117-3.3 can be evaluated for this type of application.
However, thermal performance becomes important when the load current increases.
For example, at 5V input and 3.3V output, the voltage difference is 1.7V.
At 800mA, this represents approximately 1.36W of power dissipation.
The PCB and regulator package therefore need to be capable of removing the generated heat.
For lower-current applications, the thermal requirements are less demanding.
For an embedded system using a conventional 5V input and a moderate 3.3V load, either regulator family may be worth evaluating.
However, the final selection should consider the complete power architecture.
A switching regulator may be more appropriate when:
Input voltage is much higher than 3.3V
Output current is high
Battery life is important
Power efficiency is critical
Thermal dissipation is limited
An LDO remains attractive when the circuit requires a simple, low-cost power rail and the voltage drop and current requirements are acceptable.
The LM1117 family remains widely used and is available in multiple fixed-output and adjustable versions.
TI also identifies the TLV1117 as a newer drop-in alternative to LM1117.
This is relevant for engineers designing new products or reviewing an existing 1117-based power supply.
Instead of comparing only AMS1117-3.3 and LM1117-3.3, designers may also evaluate newer LDO families when lower power consumption, improved efficiency, or different package requirements are important.
Before replacing one 3.3V 1117 regulator with another, engineers should verify:
3.3V output accuracy
Maximum load current
Output capacitor
Input capacitor
Thermal shutdown
Pin assignment
These checks help determine whether the proposed device can operate reliably in the existing circuit.
AMS1117-3.3 and LM1117-3.3 share the same basic purpose: generating a regulated 3.3V supply using a linear regulator.
LM1117 is an established 800mA LDO family with fixed 3.3V versions, multiple packages, current limiting, thermal shutdown, and a typical 1.2V dropout specification at 800mA.
AMS1117-3.3 can be considered for similar general-purpose 3.3V regulation applications, but the exact manufacturer's specifications should always be checked before substitution.
For a production design, the correct approach is to compare the complete part numbers and evaluate electrical, thermal, mechanical, and PCB requirements rather than assuming that all 1117 regulators are interchangeable.
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