LM is an adjustable voltage regulator IC used for shunt regulator, current regulator, and temperature controller. The LM LMC is a voltage regulator designed primar- ily for series regulator applications By itself it will supply output currents up to mA but external. Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. 2All trademarks are the property of their respective.
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LM IC Pinout, Specifications, Equivalent & Datasheet
lmm723 Which comparable ICs are so much better now? After some ping-pong TI recommended the MIL-spec part and guaranteed that this would be free from drift. Although the LM can dissipate a few mW and deliver up to mA, better use an external pass transistor to do the hard work and keep the regulator chip cool.
Compensation by the user. Minimum lmm723 voltage is ca. The current limiting feature is implemented as a transistor that is turned on by the voltage drop on a current sensing resistor.
They dont make this part anymore. You are commenting using your Twitter account.
A schematic with all suggestions implemented can be seen at the bottom of this page. This wastes some power, but speed, noise and other performance criteria are a lot better with a few volts across the pass transistor. Both have been making s for decades, and after the sale TI took over the National Semiconductor designation of LM and used their own of uA Before you specify a compensation cap, run a few tests using SPICE to see if gain and phase margins are in order.
For finding the value of output voltage for this circuit you can use the formula below:. The LM is not discontinued at all, sold by TI in the millions, available from all electronic distributors and dirt cheap. Support for external pass transistorskeeping on-chip dissipation and therefore drift low. The load must be able to drain at least the supply current of the circuit without exhibiting a voltage higher than the desired output voltage.
Relying on a buried Zener low noise reference, it can compete with a lot of newer chips when it comes to stability it does have a long term stability rating in the datasheet, few new chips have that. Current limiting sensitive to overload. The way to go is either high side sensing with an op amp that can do that, or a floating design like the famous Elektor one from 1 x LM, 2 x LM If you use current limiting, protect the base of the limiting transistor by a 1K, e.
Minimum Output for Floating Regulators. Its comparing apples and oranges.
Provide enough voltage headroom. On a transistor level, you can see some design tricks by the legendary Bob Widlar: LM is an adjustable voltage regulator Datashwet used for shunt regulator, current regulator, and temperature controller. The net and some manufacturers application notes are also a good source of information.
Extended Temperature Range available. When you ask for the same basic parameters 40V, mA, … there is simply no better IC today. People used to 3-terminal regulators are in for a culture shock caused by the amount of design aspects to consider. A PNP pass transistor can further improve noise performance. If you want precision current control, dont try to do this with a pot sampling a fraction of voltage across a shunt measurement resistor.
Take all networks into account, and make sure that the reference divider and the output sampling network present the same impedance to the error amplifier inputs. To use this IC for the different range of required output voltage, you can proceed with various circuits available in LM datasheet with having your needed output range.
A Collection of Proper Design Practices using the LM723 IC Regulator
Can serve as positive, negative, shunt, pass, floating or switching regulator or as a temperature controller. We have only a factor of ca. It can be found here. No wonder after 50 years, it is known what you may expect and what not.
The LM is a classic, now available for 50 continuous years and still going strong. If we pragmatically summarize the pros and cons of this methusalem, we end up with something like this:.
A Collection of Proper Design Practices using the LM IC Regulator – Electronic Projects for Fun
The curves of the limiting transistors Vbe voltages over temperature in the LM datasheet should make it absolutely clear that no precision can be expected here. Intolerant to missing or misdesigned compensation. Gate parasitic suppression resistors of a few Ohms are also a good idea.
You are commenting using your Facebook account. Notify me of new comments via email. The superbeta bipolars in the error amp have a low, but nonzero bias current that can cause voltage shifts of a few millivolts across voltage divider or RC filter resistors. Datashee can tailor the frequency response to your application but you also have to do that because there is no internal compensation. The datasheet is not very instructive on l723, but the floating regulator variants will fail to regulate when the load resistance becomes to high.
Try with different output voltages, load currents and input voltages. Silence or no reply. One of the best low noise regulators even today when hooked up properly. Error amp bias current. This is due to the 7. Moderate error amplifer gain. This cancels the error amps base bias currents. Input voltage goes up tp 40V constant, with 50V pulses allowed. Minimum regulated output voltage is ca.