Editing Basic Voltage Regulators

Jump to navigation Jump to search

Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.

The edit can be undone. Please check the comparison below to verify that this is what you want to do, and then save the changes below to finish undoing the edit.

Latest revision Your text
Line 20: Line 20:
 
</table><br>
 
</table><br>
  
Standard through-hole regulators typically come in TO-220 packages for low current, and TO-3P packages for currents above 1.5A. Heatsinking is typically easy, however note that regulators may or may not have a 'hot' tab, with the output electrically connected to the heatsinking tab, particularly in the case of older TO-3 metal can regulators. Electrical isolation is usually required for multiple regulators on the same heatsink -- a LM317 adjacent to a LM337 on a heatsink with the output tabs connected is a short circuit through the heatsink, causing high current and failure.
+
Standard through-hole regulators typically come in TO-220 packages for low current, and TO-3P packages for currents above 1.5A. Heatsinking is typically easy, however note that regulators may or may not have a 'hot' tab, with the output electrically connected to the heatsinking tab, particularly in the case of older TO-3 metal can regulators. Electrical isolation is required for multiple regulators on the same heatsink, a LM317 adjacent to a LM337 on a heatsink with the output tabs connected are the equivalent of a short, causing high current and failure.<br><br>
 
 
  
 
As the LM7XXX series regulators are mass produced and relatively inexpensive, 200-500mV of noise can be expected. Manufacturer datasheets typically recommend a 10-100uF decoupling capacitor be placed between output and ground to smooth the output, and give voltages clean enough for TTL operation amongst other applications.<br><br>
 
As the LM7XXX series regulators are mass produced and relatively inexpensive, 200-500mV of noise can be expected. Manufacturer datasheets typically recommend a 10-100uF decoupling capacitor be placed between output and ground to smooth the output, and give voltages clean enough for TTL operation amongst other applications.<br><br>
Line 27: Line 26:
 
Regulator pinouts are as follows:<br>
 
Regulator pinouts are as follows:<br>
 
<table border=1>
 
<table border=1>
<tr><td></td>                    <td>Pin 1</td>  <td>Pin 2 and tab</td>  <td>Pin 3</td></tr>
+
<tr><td></td>                    <td>Pin 1</td>  <td>Pin 2</td>  <td>Pin 3</td></tr>
 
<tr><td>LM78XX Fixed</td>        <td>Input</td>  <td>Gnd</td>    <td>Output</td></tr>
 
<tr><td>LM78XX Fixed</td>        <td>Input</td>  <td>Gnd</td>    <td>Output</td></tr>
 
<tr><td>LM79XX Fixed</td>        <td>Gnd</td>    <td>Input</td>  <td>Output</td></tr>
 
<tr><td>LM79XX Fixed</td>        <td>Gnd</td>    <td>Input</td>  <td>Output</td></tr>

Please note that all contributions to OpenCircuits may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see OpenCircuits:Copyrights for details). Do not submit copyrighted work without permission!

Cancel Editing help (opens in new window)