The "LM1117MPX-ADJ" is a Low Dropout (LDO) voltage regulator. Specifically, it is from the brand Texas Instruments (TI). This part is a 3-terminal adjustable voltage regulator designed to provide stable output voltage with low dropout voltage, making it ideal for powering low voltage devices in applications like consumer electronics, power management systems, and embedded devices.
Packaging:
The LM1117MPX-ADJ typically comes in a TO-220 package. This is a common package type for power semiconductors and has 3 leads. The package is designed to allow for efficient heat dissipation, a key feature for voltage regulators.
Pin Function Specifications (TO-220 Package):
Below is a detailed breakdown of the LM1117MPX-ADJ pin functions, using the standard 3-pin TO-220 package configuration:
Pin Number Pin Name Pin Function Description 1 Adjust Adjustment Pin: This pin is used to set the output voltage. An external resistor divider network is required between this pin and the ground pin. The output voltage is determined by the ratio of these resistors. This pin must be connected to the voltage divider in applications where an adjustable output is needed. 2 Output Output Pin: This pin provides the regulated output voltage. The output is stable when the input voltage exceeds the output voltage by more than the dropout voltage. It is important to ensure proper heat sinking when the device operates at high currents. 3 Input Input Pin: This pin is where the unregulated input voltage is supplied. The input voltage should be higher than the output voltage by at least the dropout voltage for proper operation. The input pin must be connected to a source capable of providing the required input voltage.Detailed Pin Function Descriptions:
Pin 1: Adjust (ADJ) Pin
This is the adjustable pin of the LM1117MPX-ADJ, used to regulate the output voltage. It is connected to a resistor divider network which sets the output voltage according to the following formula: [ V{OUT} = V{REF} \left( 1 + \frac{R1}{R2} \right) ] Where V_REF is the reference voltage (typically 1.25V). The output voltage can be varied by changing the resistor values.
Pin 2: Output Pin (VOUT)
The regulated output voltage is provided at this pin. The voltage is stable within a specified range as long as the input voltage is sufficiently higher than the desired output, considering the dropout voltage (typically 1.1V for this part).
Pin 3: Input Pin (VIN)
This is where the input voltage is supplied to the LM1117MPX-ADJ. The input voltage should always be greater than the output voltage by at least the dropout voltage to ensure proper operation.
Frequently Asked Questions (FAQ):
Here is a list of the 20 most common questions regarding the LM1117MPX-ADJ, with detailed answers.
1. What is the output voltage of the LM1117MPX-ADJ?
The output voltage is adjustable and can be set between 1.25V to 15V based on the external resistor divider.2. What is the dropout voltage of the LM1117MPX-ADJ?
The typical dropout voltage is 1.1V at 800mA of load current.3. How can I adjust the output voltage?
The output voltage can be adjusted by using an external resistor divider between the adjust pin and ground.4. Can the LM1117MPX-ADJ be used to power devices directly from a USB?
Yes, as long as the input voltage is sufficient to provide the desired output voltage, the LM1117MPX-ADJ can power devices from a USB source.5. What is the maximum current the LM1117MPX-ADJ can supply?
The LM1117MPX-ADJ can supply up to 800mA of output current.6. Is there any thermal protection built into the LM1117MPX-ADJ?
Yes, the LM1117MPX-ADJ has built-in thermal shutdown to protect against overheating.7. Can I use the LM1117MPX-ADJ in a high-power application?
The LM1117MPX-ADJ is suitable for medium-power applications, but for high-power systems, consider using a regulator with a higher current rating.8. What are the typical applications of the LM1117MPX-ADJ?
It is commonly used in power supplies, battery-powered devices, and embedded systems that require a stable low voltage output.9. Can I use the LM1117MPX-ADJ without a heat sink?
A heat sink is not always necessary, but if the regulator is supplying close to 800mA or more, a heat sink may be required for proper thermal management.10. What is the maximum input voltage for the LM1117MPX-ADJ?
The maximum input voltage is typically 20V, but it is recommended to operate within the specified voltage range to avoid damaging the regulator.11. Can I use the LM1117MPX-ADJ to power 5V devices?
Yes, you can set the output voltage to 5V using the appropriate resistor values for the voltage divider.12. How do I calculate the resistor values for the voltage divider?
Use the formula:
[ R1 = R2 \times \left(\frac{V{OUT}}{V{REF}} - 1 \right) ] where ( V{REF} ) is 1.25V and ( V{OUT} ) is the desired output voltage.13. Does the LM1117MPX-ADJ come in other packaging types?
Yes, the LM1117MPX-ADJ is available in other package types such as SOT-223 and TO-263.14. Is the LM1117MPX-ADJ suitable for mobile applications?
Yes, it is suitable for mobile applications that require low power consumption and stable output voltages.15. What is the quiescent current of the LM1117MPX-ADJ?
The quiescent current (current used by the regulator itself) is typically 5mA.16. Can I use the LM1117MPX-ADJ for low-voltage logic systems?
Yes, it is commonly used for providing stable voltage to logic circuits that require low voltage.17. What happens if the input voltage is lower than the output voltage?
If the input voltage drops below the required output voltage plus the dropout voltage, the regulator will not maintain a stable output.18. How can I improve the efficiency of the LM1117MPX-ADJ?
Using a switching regulator (buck converter) instead of a linear LDO like the LM1117MPX-ADJ can improve efficiency in high power applications.19. Is the LM1117MPX-ADJ resistant to overcurrent situations?
Yes, it includes current limiting to protect against excessive current draw.20. What is the recommended operating temperature range for the LM1117MPX-ADJ?
The recommended operating temperature range is from -40°C to +125°C.I hope this detailed overview provides you with the comprehensive information you need. If you need further clarification, feel free to ask!