Can anyone help> I would like to buy the TI circuit but cannot find any internet store offering it. Unfortunatelly there is no distributor for TI in Slovakia...

If i use a separate 5 volt supply, Do i need to tie pins 1,4 and 6 together for stable operation? I have seen some circuits that tie pin 6 &7 together. I would appreciate your help.

Sorry the submission messed up the format so much...

Here is C++ code that can be used to convert output bits setting to the two com chars to send to the LV8153:

void Lv8153::outBitsToChars(unsigned char addr, unsigned char outBits, unsigned char& c1, unsigned char& c2) { // Output format to the LV8153 is // {St0 St1 A0-2 D0-3 Sp} {St0 St1 A0-2 D4-7 Sp} // where St0=0, St1=1, Sp=1 // St0 and Sp come directly from RS_232 protocol; // St1 to D3 and St1 to D7 come from the output chars (LSB to MSB) // So our output bits, MSB to LSB, are: // D3 D2 D1 D0 A2 A1 A0 1 // D7 D6 D5 D4 A2 A1 A0 1 addr &= 7;

c1 = 1 + (addr << 2); c2 = c1;

c1 |= ((outBits & 0x0f) << 4); c2 |= (outBits & 0xf0);

return; }

Thank you all for your responses. It has been very satisfying to have so many people feel strongly enough to post so many comments. My submissions are usually developed with what you guys in mind, for publication that in most instances require more than a few hours to create and document.

For those interested in schematic presentation correctness...GET OVER IT!! you have missed the point of the article and either should take a serious look at what is important to you, take this 'ism' as a challenge to submit your own idea, become a larger a player and ... 'get a life'.

I believe readers are smart and will find more value in learning from what they read than from being manipulated by the author or editor and 'dumped' into a single application.

I'm having a belated second look at this circuit. You are teaching an old dog new tricks! Thanks. WB

I'm just starting out in electronics and ran across this article. I would like to try it but have some other questions about it. Is someone willing to converse via email and help me along? Thanks in advance..... James (jimshourts yahoo com) (fill in the blanks)

please i want any equivelant for (74LV8153).

or there is any one implement it using 8250

uart ?

I got some of these chips a while back (TI will send you free samples in the DIP format), but couldn't get a response from them on the output pins. I'll try your schematic and exe program to see if I can get them to work. At least now I have info on a setup that does actually work. Using the cheap 74hct259 latching chips I should be able to get up to 120 individually controlled output lines per 74LV8153 chip (I've done this type thing using the 8 data pins on the parallel port).

Bill;

Great circuit and nice presentation of data. It was easy reading and a clear schematic.

To anonymous of 7/10/2005, inquiring about distributors of this device, preferably in DIP: I searched the TI website (www.ti.com) under that part number. The DIP version has an "N" suffix - TI says DigiKey stocks it but there's a 14 week delivery. If you just want a few, try contacting your local TI rep for samples, or even for other suggestions.

Coincidentally, the Pease Porridge column in this same issue (ED online 10521) mentions kits that convert to DIP style.

Hope this helps.

very good circuit

Nice circuit. How hard would it be to adapt to a USB port? Too many boards and PC's have forsaken the RS232C interface.

Do any distributors sell 74LV8153s, preferably in DIP package?

One of the best Design Briefs I've seen in years! Thanks!

It's amazing how a person tries to educate others to have people come down on him for the littlest of things. I don't have the best electronic background but i even understood what you meant. Great job. I learned alot from this circuit. I even have plans for this.

It is a nice circuit, with a convenient usage of pin 20 (Vcc2 on datasheet) for level conversion and current boosting (if needed).

My previous comment was not clear on the supply situation in case the terminal with D3 is not used. The circuit is supplied from the RS-232 source and the current is limited by what that source can provide. Thanks to the 74L05, the circuit itself is supplied with 5.0 V while the high output voltage on D0-D7 is 5.0 V - VD3 - voltage drop across the saturated output transistor or about 4.1 V when the OUTSEL terminal is set high.

To the 6/28/05 comment: As the text says, the diodes allow the circuit to work either from power supplied from the RS-232 connector (in which case you have to accept the voltage (less the forward voltage drop across D2) and the current available from that source, OR you can connect your own higher OUTPUT voltage and draw any needed current through D3, while D2 cuts off the output power supply from providing power to (or preventing it from frying) the rest of the circuit. To both the 6/28/05 and 6/29/05 comments: The schematic should not surprise anyone. A 3-terminal voltage regulator cannot be misunderstood no matter how it is drawn, with or without terminal labels. I wouldn't have drawn it that way myself, but...

While I can figure out the correct pinout of U2 (78L05), I second the first comment. For clarity, C2 could have been moved to the left of U2. Overall, a neat little circuit.

I have never seen a 7805-type circuit shown with its input on the right and its output coming out the top, but gosh if that isn't what it looks like is being done in this circuit. It'd be nice to know for sure, you know, with some marking on the 7805 as to what was what.

I also wonder exactly what the screw terminal second from the top right does, since it cannot be a power output and cannot power the circuit externally -- back to back diodes prevent it.