Voltage Regulator LM1117T TO-220 (5 pack)

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Overview

• LM1117-3.3, LM1117-5.0, or LM1117-ADJ (See selection options)
  
• Package: TO-220
• Input voltage: 15 V MAX
• Output voltage: 3.3V FIXED, 5.0V FIXED, or 1.25V to 13.8V ADJUSTABLE
• Current draw: 0.8A MAX
• 1.2V dropout at 0.8A
• 5-pack
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These are a must-have in your collection bin. When you need to regulate down to 3.3V, 5.0V, or an adjustable voltage these components come in handy.

Pinout Diagram

See the diagram below for the pinouts of the TO-220 LM1117 group.

Application

For the FIXED output version of the LM1117 (3.3V and 5.0V), we recommend adding electrolytic capacitors (exact values are project-specific, but most of the time 10uF is sufficient) on both input and output to improve noise. Also, when running at full load (0.8A), you should properly a heat sink on these. See the schematic below for a typical application example.

For the ADJUSTABLE version of the LM1117, we recommend the following typical application circuit as shown in the schematic below.

To set the output voltage the resistors R1 and R2 have to be chosen properly. The formula to set the output voltage is as follows:

Understanding Dropout Voltage

The LM1117T has a dropout voltage of 1.2V when drawing the max current of 0.8A. As an example in order to properly regulate the output voltage to 3.3V, the input voltage needs to be at minimum 3.3V + 1.2V = 4.5V. If the input voltage is less than 4.5V, you may find that the output will not be at 3.3V or stable. Similarly for the other voltage outputs. The dropout is a function, among other things, of the current draw. If drawing less than 0.8A, then the dropout will be less than 1.2V.

HACK

The package TO-220 makes for a great hack when used in conjunction with the Proto-Full. The Vin and Vout pins of the voltage regulator are soldered into the left and right positive voltage rails. This is done at the mid-section of the Proto-Full where the rails are disconnected by default. The GND pin of the voltage regulator is soldered into the negative voltage rail. This is done by slightly bending the GND pin backward to reach the first through-hole of the negative rail. The left and right negative voltage rails have been bridged to make an electrical connection. Note that two smoothing capacitors are soldered across the positive and negative rails on either side of the Vin and Vout. This is not always necessary but recommended.

With this configuration, there are two immediate advantages. The first advantage is that two voltage rails are at different levels. The left is at the supply voltage and the right at a lower down-regulated voltage. This is useful when working with different voltage levels simultaneously. The other advantage is that this configuration uses minimal space, as none of the 5-pin breakout rows are used.

Package Contents

• 5pcs