Difference between revisions of "OPTOFAST"

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* 49x49mm
 
* 49x49mm
 
* (4) 4-40 mounting holes
 
* (4) 4-40 mounting holes
 +
 +
== Schematic (One channel) ==
 +
 +
[[File:OPTOFAST-2-Schematic-TransIn.PNG]]
 +
 +
* U1 represents U1-U4 (channels 1-4)
 +
* Q1 represents Q1-Q4 (channels 1-4)
 +
* R1 (VCC) represents R1,R4,R7,R10 (channels 1-4)
 +
* R2 (DIR) represents R2,R5,R8,R11 (channels 1-4)
 +
* R3 (BASE) represents R3,R6,R8,R12 (channels 1-4)
 +
* R13 (FAST) represents R13-R16 (channels 1-4)
 +
* R17 (COLL) represents R17-R20 (channels 1-4)
 +
 +
=== Input Options ===
 +
 +
* Refer to schematic for impact of options
 +
 +
==== Use Input Transistor - Standard Option ====
 +
 +
* Common VCC in option
 +
* Install transistor Q1
 +
* R1 = 150
 +
** LED current is 3.5V/150 Ohms = 23 mA
 +
** CTR = .20, 4.7 mA
 +
* R2 = Do not populate
 +
* R3 = 10K
 +
** Base drive ~ (Vin - 0.7V)/R3
 +
** At 5V drive this is 4.3V/R3
 +
*** Using R3=10K at 5V this is 0.43mA Ib
 +
*** HFE (MMBT3904) = 100 min
 +
*** That is potentially 43 mA (in the switching range of the transistor)
 +
**** Collector resistor and LED voltage drop are current limiter
 +
** At 3.3V drive this is (3.3-0.7)/10K = .26mA Ib
 +
*** HFE = 100 min
 +
*** That is 26 mA (in the switching range of the transistor)
 +
* H1 do not short
 +
 +
=== Direct Drive - Special Option ===
 +
 +
[[File:OPTOFAST-2-Schematic-Direct.PNG]]
 +
 +
* Do not install Q1
 +
* Do not install R1
 +
* R2 = 150
 +
** Input current = LED current = 3.5V/150 Ohms = 23 mA
 +
* Do not install R3
 +
* Do not install Q1
 +
* Short H1
 +
 +
== Output Options ==
 +
 +
=== Standard Output ===
 +
 +
* R17 = 1.2K
 +
** 5V/1.2K = 4.1mA of output transistor B-E current
 +
** Leaves 4.7-4.1 mA = 600 uA of output low current
 +
 +
=== Open Collector Output - Special Option ===
 +
 +
* Do not install R17
 +
 +
=== Fast Option - Standard ===
 +
 +
* R13 = 20K (empirically determined from the scope eye)
 +
 +
== Connectors ==
 +
 +
=== P1 - Input ===
 +
 +
8-pin, right angle, 0.1" pitch
 +
 +
# Vcc (In)
 +
# Vcc (In)
 +
# IN 1
 +
# IN 2
 +
# IN 3
 +
# IN 4
 +
# GND (In)
 +
# GND (In)
 +
 +
=== P2 - Output ===
 +
 +
8-pin, right angle, 0.1" pitch
 +
 +
# Vcc (Out)
 +
# Vcc (Out)
 +
# OUT 1
 +
# OUT 2
 +
# OUT 3
 +
# OUT 4
 +
# GND (Out)
 +
# GND (Out)
 +
 +
== Test Card Measurements ==
 +
 +
[[File:OptoFast-TestSetup-720px.jpg]]
 +
 +
=== Setup===
 +
 +
* Goal was to determine the performance of the OPTOFAST card
 +
* 5V operation
 +
* Same 5V input/output power supply
 +
* Each of the channels were configured uniquely/individually
 +
* MHS-5200A - Digital DDS Dual-channel Signal Generator
 +
** 1 KHz square wave
 +
** 5V signal level
 +
* Single channel checked at a time
 +
* Oscilloscope
 +
** Rigol DS1054Z
 +
** 50 MHz
 +
** Ultra Sigma software used for screen captures
 +
 +
=== Notes ===
 +
 +
* Note that the input buffer transistor inverts the signal
 +
* Built a card that has four different configurations
 +
* Options
 +
** Fast/Slow
 +
** Direct drive input LED/Transistor Buffered input
 +
 +
=== Test Results===
 +
* Channel Fast/Slow TransBuff/Direct Input Rise/Fall Time(uS)
 +
1 Slow Transistor Buffer Fall 28.6
 +
1 Slow Transistor Buffer Rise 1.8
 +
2 Fast Transistor Buffer Fall 6.68
 +
2 Fast Transistor Buffer Rise 3.6
 +
3 Slow Direct Input Fall 1.84
 +
3 Slow Direct Input Rise 27.4
 +
4 Fast Direct Input Fall 4.24
 +
4 Fast Direct Input Rise 5.28
 +
</pre>
 +
 +
=== Observations ===
 +
 +
* Input Transistor effect
 +
** Value of the input transistor is that does not require a high drive level input
 +
** The input transistor has very little effect on speed - a couple hundred nS slower than direct drive
 +
** The inversion effect of the input transistor moves the "slow" time around
 +
** Downside of the input transistor is that it has less noise immunity since the transistor turns on at 0.6V vs the internal LED in the optocoupler at 1.5V?
 +
* Output "fast" circuit
 +
** Output pullup of 4.7K affects the rise time of the output
 +
** The fast is faster, but not in some conditions
 +
** Average of rise/fall is better
 +
** Transistor buffer instance rise input is slower with the fast output
 +
** Fast output helps the output rise time
 +
 +
=== Ch1-Slow-NPNBuffer-InFall ===
 +
 +
[[File:Ch1-Slow-NPNBuffer-InFall.png]]
 +
 +
=== Ch1-Slow-NPNBuffer-InRise ===
 +
 +
[[File:Ch1-Slow-NPNBuffer-InRise.png]]
 +
 +
=== Ch2-Fast-NPNBuffer-InFall ===
 +
 +
[[File:Ch2-Fast-NPNBuffer-InFall.png]]
 +
 +
=== Ch2-Fast-NPNBuffer-InRise ===
 +
 +
[[File:Ch2-Fast-NPNBuffer-InRise.png]]
 +
 +
=== Ch3-Slow-Direct-InFall ===
 +
 +
[[File:Ch3-Slow-Direct-InFall.png]]
 +
 +
=== Ch3-Slow-Direct-InRise ===
 +
 +
[[File:Ch3-Slow-Direct-InRise.png]]
 +
 +
=== Ch4-Fast-Direct-InFall ===
 +
 +
[[File:Ch4-Fast-Direct-InFall.png]]]
 +
 +
=== Ch4-Fast-Direct-InRise ===
 +
 +
[[File:Ch4-Fast-Direct-InRise.png]]
 +
 +
== Layout ==
 +
 +
[[File:OPTOFAST-2 PWB.PNG]]

Revision as of 21:36, 13 March 2022

Tindie-mediums.png

OPTOFAST - 4 Channel Optocoupler Card

See our other Optocoupler cards

  • OPTOFAST-2 - Speed improved 4 channel optocoupler card - Suggested replacement for this card
  • OPTOSMALL - Four channel optocoupler card
  • OPTOOUT8-I2C - Eight channel optocoupler card - I2C interface
  • OPTOUSB - Optically coupled USB to FTDI interface
  • OPTOFASTBI - Two Optos in Two Directions

Features

  • Opto-Isolator card
  • 4-Channels
  • 4N25 Optoisolators
  • Input /Output isolation
  • Transistor driver for Opto LED reduces required drive from 10 mA to under 500 uA
  • Input channels share their own common VCC/Ground
  • Output channels share their own common Vcc/Ground
  • 8-pin header for input
  • 8-pin header for output
  • Configuration Options (Speed enhanced, Bypass Input transistors, Remove Output collector resistors)
  • 49x49mm
  • (4) 4-40 mounting holes

Schematic (One channel)

OPTOFAST-2-Schematic-TransIn.PNG

  • U1 represents U1-U4 (channels 1-4)
  • Q1 represents Q1-Q4 (channels 1-4)
  • R1 (VCC) represents R1,R4,R7,R10 (channels 1-4)
  • R2 (DIR) represents R2,R5,R8,R11 (channels 1-4)
  • R3 (BASE) represents R3,R6,R8,R12 (channels 1-4)
  • R13 (FAST) represents R13-R16 (channels 1-4)
  • R17 (COLL) represents R17-R20 (channels 1-4)

Input Options

  • Refer to schematic for impact of options

Use Input Transistor - Standard Option

  • Common VCC in option
  • Install transistor Q1
  • R1 = 150
    • LED current is 3.5V/150 Ohms = 23 mA
    • CTR = .20, 4.7 mA
  • R2 = Do not populate
  • R3 = 10K
    • Base drive ~ (Vin - 0.7V)/R3
    • At 5V drive this is 4.3V/R3
      • Using R3=10K at 5V this is 0.43mA Ib
      • HFE (MMBT3904) = 100 min
      • That is potentially 43 mA (in the switching range of the transistor)
        • Collector resistor and LED voltage drop are current limiter
    • At 3.3V drive this is (3.3-0.7)/10K = .26mA Ib
      • HFE = 100 min
      • That is 26 mA (in the switching range of the transistor)
  • H1 do not short

Direct Drive - Special Option

OPTOFAST-2-Schematic-Direct.PNG

  • Do not install Q1
  • Do not install R1
  • R2 = 150
    • Input current = LED current = 3.5V/150 Ohms = 23 mA
  • Do not install R3
  • Do not install Q1
  • Short H1

Output Options

Standard Output

  • R17 = 1.2K
    • 5V/1.2K = 4.1mA of output transistor B-E current
    • Leaves 4.7-4.1 mA = 600 uA of output low current

Open Collector Output - Special Option

  • Do not install R17

Fast Option - Standard

  • R13 = 20K (empirically determined from the scope eye)

Connectors

P1 - Input

8-pin, right angle, 0.1" pitch

  1. Vcc (In)
  2. Vcc (In)
  3. IN 1
  4. IN 2
  5. IN 3
  6. IN 4
  7. GND (In)
  8. GND (In)

P2 - Output

8-pin, right angle, 0.1" pitch

  1. Vcc (Out)
  2. Vcc (Out)
  3. OUT 1
  4. OUT 2
  5. OUT 3
  6. OUT 4
  7. GND (Out)
  8. GND (Out)

Test Card Measurements

OptoFast-TestSetup-720px.jpg

Setup

  • Goal was to determine the performance of the OPTOFAST card
  • 5V operation
  • Same 5V input/output power supply
  • Each of the channels were configured uniquely/individually
  • MHS-5200A - Digital DDS Dual-channel Signal Generator
    • 1 KHz square wave
    • 5V signal level
  • Single channel checked at a time
  • Oscilloscope
    • Rigol DS1054Z
    • 50 MHz
    • Ultra Sigma software used for screen captures

Notes

  • Note that the input buffer transistor inverts the signal
  • Built a card that has four different configurations
  • Options
    • Fast/Slow
    • Direct drive input LED/Transistor Buffered input

Test Results

  • Channel Fast/Slow TransBuff/Direct Input Rise/Fall Time(uS)

1 Slow Transistor Buffer Fall 28.6 1 Slow Transistor Buffer Rise 1.8 2 Fast Transistor Buffer Fall 6.68 2 Fast Transistor Buffer Rise 3.6 3 Slow Direct Input Fall 1.84 3 Slow Direct Input Rise 27.4 4 Fast Direct Input Fall 4.24 4 Fast Direct Input Rise 5.28

Observations

  • Input Transistor effect
    • Value of the input transistor is that does not require a high drive level input
    • The input transistor has very little effect on speed - a couple hundred nS slower than direct drive
    • The inversion effect of the input transistor moves the "slow" time around
    • Downside of the input transistor is that it has less noise immunity since the transistor turns on at 0.6V vs the internal LED in the optocoupler at 1.5V?
  • Output "fast" circuit
    • Output pullup of 4.7K affects the rise time of the output
    • The fast is faster, but not in some conditions
    • Average of rise/fall is better
    • Transistor buffer instance rise input is slower with the fast output
    • Fast output helps the output rise time

Ch1-Slow-NPNBuffer-InFall

Ch1-Slow-NPNBuffer-InFall.png

Ch1-Slow-NPNBuffer-InRise

Ch1-Slow-NPNBuffer-InRise.png

Ch2-Fast-NPNBuffer-InFall

Ch2-Fast-NPNBuffer-InFall.png

Ch2-Fast-NPNBuffer-InRise

Ch2-Fast-NPNBuffer-InRise.png

Ch3-Slow-Direct-InFall

Ch3-Slow-Direct-InFall.png

Ch3-Slow-Direct-InRise

Ch3-Slow-Direct-InRise.png

Ch4-Fast-Direct-InFall

Ch4-Fast-Direct-InFall.png]

Ch4-Fast-Direct-InRise

Ch4-Fast-Direct-InRise.png

Layout

OPTOFAST-2 PWB.PNG

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