74S140 LINE DRIVER DOWNLOAD

It has the lowest DC current drive requirement of 3. To prevent this from happening, my company has developed derating rules that prevent anyone from designing all the way up against the data sheet limits. My initial response to his inquiry was this: For example, LVT 3. Your points are well taken, especially about the power sequencing mess.

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The series-terminated circuit in Figure 4 places all the attenuation at the source end of the line. This makes a good series termination. Plus, there's enough attenuation that we may not have to worry about overdriving anything. If the layout is not "already done" I would consider specifying a higher impedance transmission line and raising R2 to reduce the driver current. I see a great number of these problems each year.

I keep a list of the most common digital design problems I see each year, and constantly remind our designers about these common problems.

74S Datasheet(PDF) - Fairchild Semiconductor

The maximum specified high drive current for any modern device that I know of is 24 ma 74ACs for example lins only gets you to 1. The ohm series resistor you suggest is typically not large enough to limit the current in this case to a safe level. In reaction to that response, my good friend James Oine, author of "Signal and Power Integrity in Digital Systems", McGraw-Hill,and a highly experienced engineer at Northrop Grumman, writes to suggest that the solution I proposed to Mehran in "Law of Product Development" could be impossible!

I will have to terminate on the PCB. What I don't like about Figure 3 is that it takes three parts. This structure uses an open-collector pull-down only type of TTL driver directly coupled to the ohm line, terminated at the end with 50 ohms to 3. What is the input impedance of the source inputs and gates? At the destination end, install a shunt termination resistance of 50 ohms.

Dual 4-Input NAND 50?٠Line Driver

If that is the case, the problem with your suggested simple 22 and 50 ohm divider is that there are few logic devices I know of only one with 7s140 drive strength to drive that low of an impedance to the proper 3.

Achieving both attenuation and termination requires two resistors.

Message 4 of The problem with this circuit, and it may not be a problem depending on the application and the settling time permitted, is that the initial SURGE current required to drive the structure from low to high is 44 mA.

What is the output impedance of the "out" pins?? The 5V driver in that case may overdrive the 3. The burn-out problem is subtle. Message 6 of I took another look through the manual of theand it suggests kine with at 74a140 resistor in series with a pF capacitor.

I find that when we make assumptions about the power sequence, or the initial logic state, someone inevitable violates those assumptions either during test or during design 74s104. This places a split end termination at the endpoint ohms to 3.

74S140 Datasheet PDF

You could use a TTL to 50 ohm line driver ie 74Sit will invert your signal though. Our policy at Northrop is that all circuits must be designed to tolerate any power sequence. R2 must be about 1: Yes, most x-ray detectors use 50 ohm TTL which is either 0 to 5V into 50 ohm or 0 to 2. I would think 75 ohms is correct, since it is a high speed card. In order to get 3.

50 Ohm, 5v driver needed | Electronics Forums

I need to get out the trigger out and gate signals also. I suppose you could parallel CMOS outputs to get more drive. Let's begin by calculating the current required to make the original solution Figure 1 operate.

For example, LVT 3. That makes quite a difference!