LM3524 | Electronic Project Circuits

Posts Tagged ‘LM3524’

Pulse width modulator by LM3524

* use a large surface ground track/fill for this circuit, otherwise the LM3524 will not work reliably!

* mount the two potentiometers through the enclosure, as shown in the picture on the start of this page (these pots are used to control the frequency and duty cycle)

* the driver is based on the LM3524 PWM (Pulse width modulator)chip, adaptation to TL494 or some newer chip should be easy (just compare pin-outs). Equivalents: CA3524, UC3524, SG3524. These are classic PWM ICs, and should be available just about anywhere, for cheap.

* to keep oscillator noise low and eliminate errors (those comparators inside LM3524 are sensitive…), use a large ground plane on the PCB

* timing capacitor C1 should be between 1nF and 22nF, 10nF is a good start. The cap must be immediately next to the chip, and connect directly to the ground plane.

* it would be a good idea to place a 3-pin switch between the power section 12V out and the 12V input for this section, together with a two-color LED (red+green) and series 6.8k resistor, to indicate whether this driver section is running or not – i.e. the flyback is running or not.

* the MIC-AMP lead to the BC547B transistor comes from the audio sense section

* I-SENSE is the current sense feedback signal from the MOSFET section and is only a few 100 millivolts, so you should use a thin shielded audio cable for signal interconnection
Source: http://users.tkk.fi/~jwagner/tesla/tv-driver/schematics.htm

Be the first to comment - What do you think? Posted by admin - January 25, 2008 at 3:22 pm

Categories: Electronic Control, Motor controller Tags: LM3524, Motor controller, PWM-Speed-Motor

13.8V 40A Switching Power Supply By LM3524 and LM324

This is circuit 13.8V, 40A Switching Power Supply,
It is high current power supply switching regulator.
And Nice Circuit for power user.

_______________________________
By Manfred Mornhinweg, XQ2FOD

This article was originally published (in a slightly modified form) in the QST magazine, December 1998 and January 1999, and in the Radio Amateur’s Handbook, 1999. Visit the American Radio Relay League for information on these publications, and a world of ham radio related things!

Design decisions
There are several different topologies for switchers in common use, and the first decision a designer must take is which of them to consider. Among the factors affecting the decision are the power level, the number of outputs needed, the range of input voltage to be accepted, the desired tradeoff between complexity, quality and cost, and many more. For this power supply I decided to use the half bridge forward converter design. This topology connects the power transformer to a bridge formed by two power transistors and two capacitors. It is reasonably simple, puts relatively low stress on the power transistors, and makes efficient use of the transformer’s magnetic capabilities.The second basic decision is which switching frequency to use. The present trend is to use ever higher frequencies. But by doing so it becomes more difficult to filter out the RF noise inevitably generated by the switching. So I decided to stay at a low switching frequency of only 25 kHz for the full cycle, which due to the frequency doubling effect of the rectifiers results in 50 kHz on the output filter.

For the main switching elements, bipolar transistors or MOSFETs can be used. Bipolars have lower conduction losses, while MOSFETs switch faster. As in this design I wanted to keep the RF noise at an absolute minimum, very fast switching was not desired, so I used bipolar transistors. But these tend to become too slow if the driving is heavier than necessary. So, if the transistors have to switch at varying current levels, the drive to them must also be varied. This is called proportional driving, and is used in this project.

The half bridge converter is best controlled by pulse width modulation. There are several ICs available for this exact purpose. I chose the 3524, which is very simple to use and easy to find. Any 3524 will do the job. It can be an LM3524, SG3524, etc.

This basically ends the big decisions. From now on, designing the circuit is a matter of calculating proper values for everything.