OPTOFAST

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)

• 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
• H1 do not short

VCC(In)	5.00	3.30	V
R1	180.00	100.00	Ohms
Vf LED	1.30	1.30	V
V LED	3.70	2.00	V
Icc	20.56	20.00	mA
CTR	0.20	0.20	A/A
Iout	4.11	4.00	mA
VCC (Out)	5.00	3.30	V
RCOL	2200.00	2200.00	Ohms
I COL	2.27	1.50	mA
Iol	1.84	2.50	mA
Ioh	2.27	1.50	mA

Direct Drive - Special Option

• 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

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

Ch1-Slow-NPNBuffer-InFall

• 28.6uS

Ch1-Slow-NPNBuffer-InRise

• 1.8uS

Ch2-Fast-NPNBuffer-InFall

• 6.68uS

Ch2-Fast-NPNBuffer-InRise

• 3.6uS

Ch3-Slow-Direct-InFall

• 1.84uS

Ch3-Slow-Direct-InRise

• 27.4uS

Ch4-Fast-Direct-InFall

• 4.24uS

]

Ch4-Fast-Direct-InRise

• 5.28uS

Layout