Converting from TTL Voltage Levels

D

David Moreno

Jan 1, 1970
0
Hi!

I've to convert a signal from TTL levels to custom levels 1.5V-2.2V.
My problem is that the source signal has no constant frecuency, so my
original aproach using a capacitor and a voltage divider isn't really
working.

My next aproach will be to cut the signal at the top (2.2V) and the
bottom (1.5V), but I've no idea how I will deal with it. Any
suggestions ?

Thanks for all =)
 
S

Spehro Pefhany

Jan 1, 1970
0
Hi!

I've to convert a signal from TTL levels to custom levels 1.5V-2.2V.
My problem is that the source signal has no constant frecuency, so my
original aproach using a capacitor and a voltage divider isn't really
working.

My next aproach will be to cut the signal at the top (2.2V) and the
bottom (1.5V), but I've no idea how I will deal with it. Any
suggestions ?

Thanks for all =)


Here is one possibility:

+5
o
|
.-.
| | R1
| |
HCT buffer '-'
|
|\ ___ |
-| >-----|___|---|-----------o
|/ |
R2 .-.
| |
| | R3
'-'
|
|
===
GND

R1 = 9.1K

R2 = 20K

R3 = 4.7K series with 180 ohms

Best regards,
Spehro Pefhany
 
R

Rene Tschaggelar

Jan 1, 1970
0
David said:
Hi!

I've to convert a signal from TTL levels to custom levels 1.5V-2.2V.
My problem is that the source signal has no constant frecuency, so my
original aproach using a capacitor and a voltage divider isn't really
working.

My next aproach will be to cut the signal at the top (2.2V) and the
bottom (1.5V), but I've no idea how I will deal with it. Any
suggestions ?

Given fixed levels, at which CMOS is better that TTL, a subtractor,
meaning an OpAmp with 4 resistors should do what you need.
TTL might need a pullup to have a real level.

Rene
 
J

Jim Thompson

Jan 1, 1970
0
Given fixed levels, at which CMOS is better that TTL, a subtractor,
meaning an OpAmp with 4 resistors should do what you need.
TTL might need a pullup to have a real level.

Rene

An OpAmp wouldn't be fast enough.

Spehro's HCT buffer plus resistor network is perfect.

(Or nearly so... might need some speed-up caps to compensate for a
capacitive load :)

...Jim Thompson
 
S

Spehro Pefhany

Jan 1, 1970
0
An OpAmp wouldn't be fast enough.

Spehro's HCT buffer plus resistor network is perfect.

(Or nearly so... might need some speed-up caps to compensate for a
capacitive load :)

...Jim Thompson

Eh? There's no load in the spec.. ;-)

Best regards,
Spehro Pefhany
 
K

Ken Smith

Jan 1, 1970
0
Hi!

I've to convert a signal from TTL levels to custom levels 1.5V-2.2V.
My problem is that the source signal has no constant frecuency, so my
original aproach using a capacitor and a voltage divider isn't really
working.

My next aproach will be to cut the signal at the top (2.2V) and the
bottom (1.5V), but I've no idea how I will deal with it. Any
suggestions ?

Thanks for all =)

How about a device like a 74HC4053 to switch between the two DC
voltages. If you've already got the supplies, it may be the lowest parts
count way to go.
 
R

Rene Tschaggelar

Jan 1, 1970
0
Jim said:
An OpAmp wouldn't be fast enough.

Spehro's HCT buffer plus resistor network is perfect.

(Or nearly so... might need some speed-up caps to compensate for a
capacitive load :)

There wasn't a speed requirement either.
That depends on the Opamp. A THS4275 @5V or an OPA687 @5V or a
THS 3201 @6V should all be fast enough for the usual. All drive
50 Ohms, BTW.

Rene
 
J

John Fields

Jan 1, 1970
0
Hi!

I've to convert a signal from TTL levels to custom levels 1.5V-2.2V.
My problem is that the source signal has no constant frecuency, so my
original aproach using a capacitor and a voltage divider isn't really
working.

My next aproach will be to cut the signal at the top (2.2V) and the
bottom (1.5V), but I've no idea how I will deal with it. Any
suggestions ?


5.0V>----------------------+
|1%
[5.1K] RL OPEN 100K
CMOS | ------|------
TTL>---[BUFFER]-----[11K]--+-------+---> EOUT, HIGH 2.23 2.19
1% | | EOUT, LOW 1.52 1.49
[2.8K] [RL]
|1% |
0V>------------------------+-------+
 
J

John Fields

Jan 1, 1970
0
There wasn't a speed requirement either.
That depends on the Opamp. A THS4275 @5V or an OPA687 @5V or a
THS 3201 @6V should all be fast enough for the usual. All drive
50 Ohms, BTW.
 
M

M.Randelzhofer

Jan 1, 1970
0
David Moreno said:
Hi!

I've to convert a signal from TTL levels to custom levels 1.5V-2.2V.
My problem is that the source signal has no constant frecuency, so my
original aproach using a capacitor and a voltage divider isn't really
working.

My next aproach will be to cut the signal at the top (2.2V) and the
bottom (1.5V), but I've no idea how I will deal with it. Any
suggestions ?

Thanks for all =)

Apart from using resistors and capacitors for voltage dividing, there are
readily availlable chip solutions.
Simply use an 5V tolerant buffer like:

http://www.fairchildsemi.com/ds/NC/NC7SZ125.pdf

It's operation voltage starts at 1.65V, but Xilinx uses these buffers in
their parallel download cable IV, and they specify an operating voltage from
1.5 to 5V.

If your TTL levels are true TTL levels which only rise to 3.6V, you can use
the AUP single gates as buffers downto 0.8V
http://focus.ti.com/lit/ds/symlink/sn74aup1g57.pdf


MIKE
 
B

Ban

Jan 1, 1970
0
Rene said:
There wasn't a speed requirement either.
That depends on the Opamp. A THS4275 @5V or an OPA687 @5V or a
THS 3201 @6V should all be fast enough for the usual. All drive
50 Ohms, BTW.

Rene

I used to do this kind of things with an LM748(30yrs ago). With zeners
and/or diodes on pin 8 you could do any output clamping on even +/-18V
supplies. But with 0.5V/us slew is too slow today.
 
D

David Moreno

Jan 1, 1970
0
Thanks to All !. I'll keep to the circuit using 3 resistors for
simplicity (and I haven't to drive a capacitive load ;)), but all the other
ideas are really useful.

John Fields said:
Hi!

I've to convert a signal from TTL levels to custom levels 1.5V-2.2V.
My problem is that the source signal has no constant frecuency, so my
original aproach using a capacitor and a voltage divider isn't really
working.

My next aproach will be to cut the signal at the top (2.2V) and the
bottom (1.5V), but I've no idea how I will deal with it. Any
suggestions ?


5.0V>----------------------+
|1%
[5.1K] RL OPEN 100K
CMOS | ------|------
TTL>---[BUFFER]-----[11K]--+-------+---> EOUT, HIGH 2.23 2.19
1% | | EOUT, LOW 1.52 1.49
[2.8K] [RL]
|1% |
0V>------------------------+-------+
 
R

Rene Tschaggelar

Jan 1, 1970
0
Ban said:
I used to do this kind of things with an LM748(30yrs ago). With zeners
and/or diodes on pin 8 you could do any output clamping on even +/-18V
supplies. But with 0.5V/us slew is too slow today.

I agree.
The OpAmps I mentioned are a bit faster. And low-impedance outputs.
Whether they are overkill or not depends on the required impedance.
The three resistors are not necessarily low-impedance.

Rene
 
R

Rene Tschaggelar

Jan 1, 1970
0
Could be.
Three resistors having what impedance ?

Rene
 
J

John Fields

Jan 1, 1970
0
Could be.
Three resistors having what impedance ?

---
Of course it depends on your source and load impedance, but for the
OP's 2.5V and 1.5V requirement, using 1% resistors between 100 ohms
and 10k ohms being fed from a zero ohm source and feeding an infinite
load, here's your choices: (You may want to check the list just to
make sure I didn't make any errors.^)


VHIGH VLOW R1 R2 R3
------------------------------------
2.215812 1.48887 187 100 383
2.206488 1.493857 187 100 392
2.213298 1.488186 191 102 392
2.196548 1.499172 187 100 402
2.203208 1.493575 191 102 402
2.217443 1.490656 196 105 402
2.187025 1.504264 187 100 412
2.193541 1.498738 191 102 412
2.207591 1.495933 196 105 412
2.214033 1.490493 200 107 412
2.184269 1.503689 191 102 422
2.198141 1.500996 196 105 422
2.204446 1.495621 200 107 422
2.21797 1.492796 205 110 422
2.189069 1.505856 196 105 432
2.195242 1.500545 200 107 432
2.208599 1.497825 205 110 432
2.221712 1.494984 210 113 432
2.180352 1.510526 196 105 442
2.186398 1.505277 200 107 442
2.199592 1.502658 205 110 442
2.212546 1.499916 210 113 442
2.214585 1.489873 215 115 442
2.190081 1.507761 205 110 453
2.202865 1.505125 210 113 453
2.204747 1.495135 215 115 453
2.213588 1.487767 221 118 453
2.180961 1.512655 205 110 464
2.193581 1.510121 210 113 464
2.195311 1.500183 215 115 464
2.203966 1.492905 221 118 464
2.216305 1.490385 226 121 464
2.184669 1.514916 210 113 475
2.186251 1.505028 215 115 475
2.194727 1.497838 221 118 475
2.206915 1.495413 226 121 475
2.215315 1.488366 232 124 475
2.18506 1.503 221 118 487
2.197087 1.500675 226 121 487
2.205303 1.493717 232 124 487
2.217036 1.491293 237 127 487
2.187667 1.505718 226 121 499
2.195706 1.498847 232 124 499
2.207288 1.496517 237 127 499
2.215261 1.489778 243 130 499
2.17863 1.510556 226 121 511
2.186497 1.503769 232 124 511
2.197933 1.501529 237 127 511
2.20574 1.494872 243 130 511
2.21357 1.488334 249 133 511
2.18895 1.506343 237 127 523
2.196595 1.499764 243 130 523
2.204265 1.493304 249 133 523
2.220995 1.493034 255 137 523
2.179611 1.511348 237 127 536
2.187087 1.504851 243 130 536
2.19459 1.498472 249 133 536
2.211147 1.498325 255 137 536
2.218502 1.491991 261 140 536
2.185311 1.503428 249 133 549
2.201701 1.5034 255 137 549
2.208899 1.497142 261 140 549
2.216119 1.490992 267 143 549
2.192631 1.508273 255 137 562
2.199678 1.502089 261 140 562
2.206749 1.496011 267 143 562
2.219229 1.491874 274 147 562
2.183261 1.513307 255 137 576
2.190149 1.5072 261 140 576
2.197065 1.501197 267 143 576
2.209362 1.497167 274 147 576
2.216239 1.491301 280 150 576
2.181013 1.5121 261 140 590
2.187778 1.506171 267 143 590
2.199898 1.502245 274 147 590
2.206628 1.496449 280 150 590
2.218517 1.492503 287 154 590
2.178864 1.510946 267 143 604
2.190812 1.507119 274 147 604
2.197402 1.501392 280 150 604
2.209124 1.497543 287 154 604
2.220685 1.493646 294 158 604
2.181473 1.51213 274 147 619
2.187916 1.506474 280 150 619
2.199466 1.502726 287 154 619
2.210857 1.498927 294 158 619
2.178819 1.511347 280 150 634
2.190202 1.507696 287 154 634
2.201429 1.503994 294 158 634
2.212507 1.500245 301 162 634
2.213294 1.488047 309 165 634
2.18131 1.512468 287 154 649
2.192378 1.508858 294 158 649
2.203299 1.505201 301 162 649
2.20392 1.493052 309 165 649
2.214812 1.489547 316 169 649
2.183113 1.513837 294 158 665
2.193872 1.510275 301 162 665
2.194323 1.498177 309 165 665
2.205057 1.494764 316 169 665
2.220201 1.492855 324 174 665
2.185115 1.503094 309 165 681
2.195698 1.499769 316 169 681
2.210668 1.497975 324 174 681
2.218397 1.491341 332 178 681
2.186159 1.504871 316 169 698
2.200951 1.503193 324 174 698
2.208511 1.496642 332 178 698
2.216096 1.490207 340 182 698
2.191632 1.508197 324 174 715
2.19903 1.501725 332 178 715
2.206454 1.495369 340 182 715
2.220516 1.493574 348 187 715
2.182689 1.513 324 174 732
2.189928 1.506605 332 178 732
2.197196 1.500324 340 182 732
2.211099 1.498634 348 187 732
2.215947 1.489507 357 191 732
2.180681 1.511563 332 178 750
2.187789 1.50536 348 187 750
2.206205 1.494719 357 191 750
2.219627 1.493022 365 196 750
2.178765 1.510191 340 182 768
2.192345 1.508711 348 187 768
2.196857 1.499721 357 191 768
2.210124 1.498125 365 196 768
2.214758 1.489434 374 200 768
2.183047 1.513708 348 187 787
2.187389 1.504786 357 191 787
2.2005 1.503293 365 196 787
2.204969 1.494669 374 200 787
2.215618 1.490335 383 205 787
2.178308 1.509645 357 191 806
2.191267 1.508251 365 196 806
2.195578 1.499691 374 200 806
2.206065 1.495448 383 205 806
2.216439 1.491193 392 210 806
2.182404 1.513011 365 196 825
2.18656 1.504514 374 200 825
2.19689 1.500359 383 205 825
2.207109 1.496192 392 210 825
2.215155 1.489407 402 215 825
2.187617 1.505323 383 205 845
2.197679 1.501244 392 210 845
2.205554 1.494542 402 215 845
2.219049 1.491724 412 221 845
2.17828 1.51032 383 205 866
2.188181 1.506331 392 210 866
2.195885 1.499713 402 215 866
2.209205 1.497004 412 221 866
2.216834 1.490511 422 226 866
2.179074 1.511211 392 210 887
2.186611 1.504673 402 215 887
2.199762 1.50207 412 221 887
2.207229 1.495655 422 226 887
2.220049 1.492937 432 232 887
2.190273 1.50716 412 221 909
2.197576 1.500824 422 226 909
2.21023 1.49821 432 232 909
2.217469 1.491991 442 237 909
2.181172 1.512041 412 221 931
2.188318 1.505782 422 226 931
2.200811 1.503268 432 232 931
2.207896 1.497124 442 237 931
2.218256 1.492194 453 243 931
2.179429 1.510543 422 226 953
2.191767 1.508125 432 232 953
2.198703 1.502053 442 237 953
2.2089 1.497213 453 243 953
2.219006 1.492387 464 249 953
2.182689 1.513 432 232 976
2.189475 1.507001 442 237 976
2.199506 1.502252 453 243 976
2.209449 1.497515 464 249 976
2.219306 1.492793 475 255 976
2.180238 1.511954 442 237 1000
2.190102 1.507296 453 243 1000
2.19988 1.50265 464 249 1000
2.209575 1.498017 475 255 1000
2.217483 1.491246 487 261 1000
2.182558 1.511343 453 243 1020
2.192203 1.50677 464 249 1020
2.201767 1.502209 475 255 1020
2.209536 1.495505 487 261 1020
2.217329 1.488924 499 267 1020
2.181162 1.512695 464 249 1050
2.190536 1.508238 475 255 1050
2.198103 1.501632 487 261 1050
2.205698 1.495147 499 267 1050
2.217826 1.491811 511 274 1050
2.183352 1.512095 475 255 1070
2.190789 1.505552 487 261 1070
2.198256 1.49913 499 267 1070
2.210255 1.495871 511 274 1070
2.21767 1.489584 523 280 1070
2.18025 1.511201 487 261 1100
2.187531 1.504868 499 267 1100
2.199342 1.501723 511 274 1100
2.206576 1.495523 523 280 1100
2.216588 1.490371 536 287 1100
2.188929 1.507306 511 274 1130
2.19599 1.501191 523 280 1130
2.205814 1.49614 536 287 1130
2.215564 1.491119 549 294 1130
2.182248 1.510888 511 274 1150
2.189197 1.504828 523 280 1150
2.1989 1.499843 536 287 1150
2.20853 1.494885 549 294 1150
2.21809 1.489955 562 301 1150
2.179382 1.510082 523 280 1180
2.188908 1.505193 536 287 1180
2.198364 1.50033 549 294 1180
2.207752 1.495492 562 301 1180
2.219631 1.491552 576 309 1180
2.179345 1.510314 536 287 1210
2.188633 1.505541 549 294 1210
2.197855 1.500793 562 301 1210
2.209557 1.496956 576 309 1210
2.217198 1.49045 590 316 1210
2.17931 1.510533 549 294 1240
2.188372 1.505872 562 301 1240
2.199902 1.502136 576 309 1240
2.207378 1.49571 590 316 1240
2.21869 1.491961 604 324 1240
2.179277 1.510743 562 301 1270
2.190641 1.507104 576 309 1270
2.197957 1.500755 590 316 1270
2.209108 1.497101 604 324 1270
2.218771 1.491709 619 332 1270
2.18175 1.511874 576 309 1300
2.188911 1.5056 604 324 1300
2.209406 1.496732 619 332 1300
2.218848 1.49147 634 340 1300
2.180219 1.510256 590 316 1330
2.191063 1.506781 604 324 1330
2.200406 1.501559 619 332 1330
2.209692 1.49638 634 340 1330
2.218921 1.491241 649 348 1330
2.179794 1.512826 604 324 1370
2.188934 1.507712 619 332 1370
2.19802 1.502639 634 340 1370
2.207054 1.497605 649 348 1370
2.218244 1.493364 665 357 1370
2.180703 1.512127 619 332 1400
2.189645 1.50713 634 340 1400
2.198536 1.502172 649 348 1400
2.209576 1.498017 665 357 1400
2.217106 1.491566 681 365 1400
2.181574 1.511459 634 340 1430
2.190326 1.506574 649 348 1430
2.20122 1.502503 665 357 1430
2.208608 1.49612 681 365 1430
2.218134 1.49057 698 374 1430
2.179832 1.512201 649 348 1470
2.190536 1.508238 665 357 1470
2.197743 1.501944 681 365 1470
2.207076 1.496495 698 374 1470
2.216359 1.491097 715 383 1470
2.182848 1.512366 665 357 1500
2.189922 1.506136 681 365 1500
2.199115 1.500761 698 374 1500
2.20826 1.495436 715 383 1500
2.217356 1.490159 732 392 1500
2.179904 1.511505 681 365 1540
2.188917 1.506225 698 374 1540
2.197884 1.500994 715 383 1540
2.206805 1.49581 732 392 1540
2.217645 1.491342 750 402 1540
2.179166 1.51145 698 374 1580
2.187961 1.506309 715 383 1580
2.196713 1.501214 732 392 1580
2.207375 1.496847 750 402 1580
2.217922 1.492469 768 412 1580
2.178463 1.511397 715 383 1620
2.187052 1.506388 732 392 1620
2.197542 1.502117 750 402 1620
2.20792 1.497835 768 412 1620
2.217132 1.492212 787 422 1620
2.180072 1.510125 732 392 1650
2.190437 1.505926 750 402 1650
2.200691 1.501712 768 412 1650
2.209776 1.496156 787 422 1650
2.21882 1.490657 806 432 1650
2.181304 1.510821 750 402 1690
2.191398 1.506698 768 412 1690
2.200319 1.501227 787 422 1690
2.209201 1.495813 806 432 1690
2.218043 1.490454 825 442 1690
2.180303 1.51265 787 422 1740
2.197712 1.501971 806 432 1740
2.206362 1.496713 825 442 1740
2.216717 1.492103 845 453 1740
2.180386 1.511915 787 422 1780
2.188922 1.506682 806 432 1780
2.197423 1.501502 825 442 1780
2.207623 1.496979 845 453 1780
2.216765 1.491248 866 464 1780
2.180466 1.511214 806 432 1820
2.188823 1.506109 825 442 1820
2.198873 1.501669 845 453 1820
2.207861 1.496019 866 464 1820
2.216813 1.490432 887 475 1820
2.178523 1.511628 825 442 1870
2.18839 1.507289 845 453 1870
2.197192 1.501736 866 464 1870
2.20596 1.496244 887 475 1870
2.216317 1.491368 909 487 1870
2.180346 1.511601 845 453 1910
2.189003 1.506123 866 464 1910
2.19763 1.500705 887 475 1910
2.207839 1.495911 909 487 1910
2.217955 1.491128 931 499 1910
2.179176 1.511389 866 464 1960
2.18763 1.506061 887 475 1960
2.19766 1.501364 909 487 1960
2.2076 1.496678 931 499 1960
2.217454 1.492005 953 511 1960
2.179942 1.510178 887 475 2000
2.189833 1.505557 909 487 2000
2.199637 1.500946 931 499 2000
2.209357 1.496347 953 511 2000
2.218143 1.490688 976 523 2000
2.180421 1.510599 909 487 2050
2.19006 1.50608 931 499 2050
2.199616 1.50157 953 511 2050
2.208236 1.495996 976 523 2050
2.218302 1.49099 1000 536 2050
2.180878 1.511001 931 499 2100
2.190277 1.506578 953 511 2100
2.198736 1.501087 976 523 2100
2.208634 1.496172 1000 536 2100
2.221704 1.495377 1020 549 2100
2.181314 1.511384 953 511 2150
2.189616 1.505974 976 523 2150
2.199354 1.501146 1000 536 2150
2.212286 1.500446 1020 549 2150
2.217017 1.489559 1050 562 2150
2.179145 1.511585 976 523 2210
2.188696 1.506859 1000 536 2210
2.201469 1.506268 1020 549 2210
2.205981 1.495466 1050 562 2210
2.220603 1.496199 1070 576 2210
2.180189 1.511419 1000 536 2260
2.192834 1.510916 1020 549 2260
2.197169 1.500182 1050 562 2260
2.211665 1.50101 1070 576 2260
2.218244 1.492033 1100 590 2260
2.187028 1.50561 1050 562 2320
2.201378 1.506548 1070 576 2320
2.207755 1.497659 1100 590 2320
2.214264 1.489013 1130 604 2320
2.178917 1.509951 1050 562 2370
2.193149 1.510978 1070 576 2370
2.199364 1.502159 1100 590 2370
2.205714 1.493583 1130 604 2370
2.221361 1.495633 1150 619 2370
2.189688 1.507349 1100 590 2430
2.195852 1.498854 1130 604 2430
2.211367 1.501012 1150 619 2430
2.219431 1.493966 1180 634 2430
2.180416 1.512322 1100 590 2490
2.186401 1.503906 1130 604 2490
2.201788 1.506168 1150 619 2490
2.209676 1.499208 1180 634 2490
2.217594 1.492381 1210 649 2490
2.192598 1.511115 1150 619 2550
2.200316 1.504237 1180 634 2550
2.208066 1.497492 1210 649 2550
2.2177 1.49212 1240 665 2550
2.191327 1.509067 1180 634 2610
2.198915 1.5024 1210 649 2610
2.208388 1.497115 1240 665 2610
2.217802 1.491872 1270 681 2610
2.182688 1.513708 1180 634 2670
2.190119 1.507118 1210 649 2670
2.199435 1.501916 1240 665 2670
2.208695 1.496755 1270 681 2670
2.219668 1.492824 1300 698 2670
2.180279 1.512396 1210 649 2740
2.189418 1.507288 1240 665 2740
2.198504 1.50222 1270 681 2740
2.209304 1.498389 1300 698 2740
2.219972 1.494526 1330 715 2740
2.181177 1.511707 1240 665 2800
2.190119 1.506716 1270 681 2800
2.200775 1.502968 1300 698 2800
2.211302 1.499187 1330 715 2800
2.215625 1.48771 1370 732 2800
2.18072 1.511755 1270 681 2870
2.191214 1.508102 1300 698 2870
2.201581 1.504413 1330 715 2870
2.205703 1.493011 1370 732 2870
2.217644 1.490548 1400 750 2870
2.182048 1.513024 1300 698 2940
2.192259 1.509424 1330 715 2940
2.196187 1.498095 1370 732 2940
2.207977 1.495726 1400 750 2940
2.219577 1.493262 1430 768 2940
2.183314 1.514234 1330 715 3010
2.187054 1.502975 1370 732 3010
2.198697 1.500698 1400 750 3010
2.210152 1.498324 1430 768 3010
2.217331 1.489769 1470 787 3010
2.188536 1.506142 1400 750 3090
2.199831 1.503867 1430 768 3090
2.206808 1.495403 1470 787 3090
2.219403 1.494108 1500 806 3090
2.18001 1.510709 1400 750 3160
2.19117 1.508518 1430 768 3160
2.197977 1.500131 1470 787 3160
2.210439 1.498924 1500 806 3160
2.21726 1.490754 1540 825 3160
2.181669 1.513621 1430 768 3240
2.188287 1.505319 1470 787 3240
2.200603 1.504209 1500 806 3240
2.207241 1.496121 1540 825 3240
2.215435 1.489214 1580 845 3240
2.179002 1.510289 1470 787 3320
2.191176 1.509275 1500 806 3320
2.197637 1.501266 1540 825 3320
2.205655 1.494444 1580 845 3320
2.215123 1.488706 1620 866 3320
2.182134 1.514134 1500 806 3400
2.188423 1.506202 1540 825 3400
2.196271 1.499462 1580 845 3400
2.20557 1.493812 1620 866 3400
2.219841 1.494546 1650 887 3400
2.179576 1.510941 1540 825 3480
2.18726 1.504282 1580 845 3480
2.196396 1.498717 1620 866 3480
2.210539 1.499547 1650 887 3480
2.220797 1.49485 1690 909 3480
2.186498 1.504008 1620 866 3570
2.200503 1.504942 1650 887 3570
2.210587 1.500341 1690 909 3570
2.21579 1.489712 1740 931 3570
2.178056 1.508521 1620 866 3650
2.191941 1.509544 1650 887 3650
2.201875 1.505027 1690 909 3650
2.206901 1.494469 1740 931 3650
2.216794 1.49011 1780 953 3650
2.182688 1.514518 1650 887 3740
2.192459 1.510092 1690 909 3740
2.197291 1.499611 1740 931 3740
2.207025 1.49534 1780 953 3740
2.217935 1.49192 1820 976 3740
2.183426 1.51495 1690 909 3830
2.18807 1.504544 1740 931 3830
2.197653 1.500358 1780 953 3830
2.20841 1.497028 1820 976 3830
2.215812 1.48887 1870 1000 3830
2.179217 1.509281 1740 931 3920
2.188651 1.505177 1780 953 3920
2.199261 1.501935 1820 976 3920
2.206488 1.493857 1870 1000 3920
2.213298 1.488186 1910 1020 3920
2.179059 1.510313 1780 953 4020
2.189511 1.507163 1820 976 4020
2.196548 1.499172 1870 1000 4020
2.203208 1.493575 1910 1020 4020
2.217443 1.490656 1960 1050 4020
2.180171 1.512172 1820 976 4120
2.187025 1.504264 1870 1000 4120
2.193541 1.498737 1910 1020 4120
2.207591 1.495933 1960 1050 4120
2.214033 1.490493 2000 1070 4120
2.184269 1.503689 1910 1020 4220
2.198141 1.500996 1960 1050 4220
2.204447 1.495621 2000 1070 4220
2.21797 1.492797 2050 1100 4220
2.189069 1.505856 1960 1050 4320
2.195242 1.500545 2000 1070 4320
2.208599 1.497825 2050 1100 4320
2.221712 1.494984 2100 1130 4320
2.180352 1.510526 1960 1050 4420
2.186398 1.505277 2000 1070 4420
2.199592 1.502658 2050 1100 4420
2.212546 1.499916 2100 1130 4420
2.214585 1.489873 2150 1150 4420
2.190081 1.507761 2050 1100 4530
2.202865 1.505125 2100 1130 4530
2.204747 1.495135 2150 1150 4530
2.213588 1.487768 2210 1180 4530
2.180961 1.512655 2050 1100 4640
2.193581 1.510121 2100 1130 4640
2.195311 1.500183 2150 1150 4640
2.203966 1.492905 2210 1180 4640
2.216305 1.490385 2260 1210 4640
2.184669 1.514916 2100 1130 4750
2.186251 1.505028 2150 1150 4750
2.194727 1.497838 2210 1180 4750
2.206915 1.495413 2260 1210 4750
2.215315 1.488366 2320 1240 4750
2.18506 1.503 2210 1180 4870
2.197087 1.500675 2260 1210 4870
2.205303 1.493717 2320 1240 4870
2.217036 1.491293 2370 1270 4870
2.187667 1.505718 2260 1210 4990
2.195706 1.498847 2320 1240 4990
2.207287 1.496517 2370 1270 4990
2.215261 1.489778 2430 1300 4990
2.17863 1.510556 2260 1210 5110
2.186497 1.503769 2320 1240 5110
2.197933 1.501529 2370 1270 5110
2.20574 1.494872 2430 1300 5110
2.21357 1.488334 2490 1330 5110
2.18895 1.506343 2370 1270 5230
2.196595 1.499764 2430 1300 5230
2.204265 1.493304 2490 1330 5230
2.220995 1.493034 2550 1370 5230
2.179611 1.511348 2370 1270 5360
2.187087 1.504851 2430 1300 5360
2.19459 1.498472 2490 1330 5360
2.211147 1.498325 2550 1370 5360
2.218502 1.491991 2610 1400 5360
2.185311 1.503428 2490 1330 5490
2.2017 1.5034 2550 1370 5490
2.208899 1.497142 2610 1400 5490
2.21612 1.490992 2670 1430 5490
2.192631 1.508273 2550 1370 5620
2.199678 1.502089 2610 1400 5620
2.206749 1.496011 2670 1430 5620
2.219229 1.491874 2740 1470 5620
2.183261 1.513307 2550 1370 5760
2.19015 1.5072 2610 1400 5760
2.197065 1.501197 2670 1430 5760
2.209362 1.497167 2740 1470 5760
2.216238 1.491301 2800 1500 5760
2.181013 1.5121 2610 1400 5900
2.187778 1.506171 2670 1430 5900
2.199897 1.502245 2740 1470 5900
2.206628 1.496449 2800 1500 5900
2.218517 1.492503 2870 1540 5900
2.178864 1.510946 2670 1430 6040
2.190812 1.507119 2740 1470 6040
2.197402 1.501392 2800 1500 6040
2.209124 1.497543 2870 1540 6040
2.220685 1.493645 2940 1580 6040
2.181473 1.51213 2740 1470 6190
2.187916 1.506474 2800 1500 6190
2.199466 1.502726 2870 1540 6190
2.210857 1.498927 2940 1580 6190
2.178819 1.511347 2800 1500 6340
2.190202 1.507696 2870 1540 6340
2.201429 1.503994 2940 1580 6340
2.212507 1.500245 3010 1620 6340
2.213294 1.488047 3090 1650 6340
2.18131 1.512468 2870 1540 6490
2.192378 1.508858 2940 1580 6490
2.203299 1.505201 3010 1620 6490
2.20392 1.493052 3090 1650 6490
2.214812 1.489547 3160 1690 6490
2.183113 1.513837 2940 1580 6650
2.193872 1.510275 3010 1620 6650
2.194323 1.498177 3090 1650 6650
2.205057 1.494764 3160 1690 6650
2.220201 1.492855 3240 1740 6650
2.185115 1.503094 3090 1650 6810
2.195698 1.499769 3160 1690 6810
2.210668 1.497975 3240 1740 6810
2.218397 1.491341 3320 1780 6810
2.186159 1.504871 3160 1690 6980
2.20095 1.503193 3240 1740 6980
2.208511 1.496642 3320 1780 6980
2.216096 1.490207 3400 1820 6980
2.191633 1.508198 3240 1740 7150
2.19903 1.501725 3320 1780 7150
2.206453 1.495369 3400 1820 7150
2.220515 1.493574 3480 1870 7150
2.182689 1.513 3240 1740 7320
2.189928 1.506605 3320 1780 7320
2.197196 1.500324 3400 1820 7320
2.211099 1.498634 3480 1870 7320
2.215947 1.489507 3570 1910 7320
2.180681 1.511563 3320 1780 7500
2.18779 1.50536 3400 1820 7500
2.201529 1.503776 3480 1870 7500
2.206206 1.494719 3570 1910 7500
2.219626 1.493022 3650 1960 7500
2.178765 1.510191 3400 1820 7680
2.192345 1.508711 3480 1870 7680
2.196857 1.499721 3570 1910 7680
2.210124 1.498125 3650 1960 7680
2.214758 1.489434 3740 2000 7680
2.183047 1.513707 3480 1870 7870
2.187389 1.504786 3570 1910 7870
2.2005 1.503293 3650 1960 7870
2.204969 1.494669 3740 2000 7870
2.215618 1.490335 3830 2050 7870
2.178308 1.509645 3570 1910 8060
2.191268 1.508251 3650 1960 8060
2.195577 1.499691 3740 2000 8060
2.206065 1.495448 3830 2050 8060
2.216439 1.491194 3920 2100 8060
2.182404 1.513011 3650 1960 8250
2.18656 1.504514 3740 2000 8250
2.19689 1.500359 3830 2050 8250
2.207109 1.496192 3920 2100 8250
2.215155 1.489407 4020 2150 8250
2.187617 1.505323 3830 2050 8450
2.197679 1.501244 3920 2100 8450
2.205554 1.494542 4020 2150 8450
2.219049 1.491724 4120 2210 8450
2.17828 1.51032 3830 2050 8660
2.188181 1.506331 3920 2100 8660
2.195885 1.499713 4020 2150 8660
2.209205 1.497004 4120 2210 8660
2.216834 1.490511 4220 2260 8660
2.179074 1.511211 3920 2100 8870
2.186611 1.504673 4020 2150 8870
2.199762 1.50207 4120 2210 8870
2.207229 1.495655 4220 2260 8870
2.220049 1.492937 4320 2320 8870
2.190273 1.50716 4120 2210 9090
2.197576 1.500824 4220 2260 9090
2.21023 1.49821 4320 2320 9090
2.217469 1.491991 4420 2370 9090
2.181172 1.512041 4120 2210 9310
2.188318 1.505783 4220 2260 9310
2.200811 1.503268 4320 2320 9310
2.207896 1.497124 4420 2370 9310
2.218256 1.492194 4530 2430 9310
2.179429 1.510543 4220 2260 9530
2.191767 1.508125 4320 2320 9530
2.198703 1.502053 4420 2370 9530
2.208899 1.497213 4530 2430 9530
2.219006 1.492387 4640 2490 9530
2.182689 1.513 4320 2320 9760
2.189475 1.507001 4420 2370 9760
2.199506 1.502252 4530 2430 9760
2.209449 1.497515 4640 2490 9760
2.219306 1.492793 4750 2550 9760
 
J

John Fields

Jan 1, 1970
0
Thanks to All !. I'll keep to the circuit using 3 resistors for
simplicity (and I haven't to drive a capacitive load ;)), but all the other
ideas are really useful.

John Fields said:
Hi!

I've to convert a signal from TTL levels to custom levels 1.5V-2.2V.
My problem is that the source signal has no constant frecuency, so my
original aproach using a capacitor and a voltage divider isn't really
working.

My next aproach will be to cut the signal at the top (2.2V) and the
bottom (1.5V), but I've no idea how I will deal with it. Any
suggestions ?


5.0V>----------------------+
|1%
[5.1K] RL OPEN 100K
CMOS | ------|------
TTL>---[BUFFER]-----[11K]--+-------+---> EOUT, HIGH 2.23 2.19
1% | | EOUT, LOW 1.52 1.49
[2.8K] [RL]
|1% |
0V>------------------------+-------+

---
Ooops...

5.1k should be 5.11k.

Using 5.11k, then multilying the values in one of the rows of the list
I posted earlier and numbering the resistors to correspond with the
resistors on the list (like this) also gives a pretty good result:


5.0V>----------------------+
|1%
[5.11K]R1
CMOS R3 |
TTL>---[BUFFER]----[10.7k]-+-------> 1.496->2.210V
1% |
[2.74K]R2
|1%
0V>------------------------+
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that John Fields <jfields@austininstrum
Using 5.11k, then multilying the values

Is this a process known only in political mathematics?
 
J

John Fields

Jan 1, 1970
0
I read in sci.electronics.design that John Fields <jfields@austininstrum


Is this a process known only in political mathematics?
 
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