Difference between revisions of "DRIVE50"

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[[file:DRIVE50_FRONT_3D.png]]
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[[File:tindie-mediums.png|link=https://www.tindie.com/products/land_boards/5075-ohm-ttl-line-driver/]]
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[[file:DRIVE50_P1080480-720PX.jpg]]
  
 
== 50 Ohm Driver Card ==
 
== 50 Ohm Driver Card ==
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=== Driver ===
 
=== Driver ===
  
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* 5x paralleled [http://cva.stanford.edu/classes/cs99s/datasheets/74AC14.pdf 74AC14] drivers
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* 5x paralleled [https://www.ti.com/lit/ds/symlink/cd74ac14.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1658486403853&ref_url=https%253A%252F%252Fwww.mouser.com%252F 74AC14] drivers
 
** 24mA per pin max current output
 
** 24mA per pin max current output
 
*** Symmetric high-low drive levels
 
*** Symmetric high-low drive levels
 
** Short-circuit proof
 
** Short-circuit proof
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*** 5V, 250 Ohms to ground is 20 mA (pins are rated for 24 mA
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*** 5V, 250 Ohms to ground is 20 mA (pins are rated for 24 mA)
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* Card input has single buffer stage
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*** 0.125 W resistor (5V output through 249 ohm resistor with output shorted to ground is 0.1 W)
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*** 3.3V, 250 Ohms to ground is 13.2 mA (pins are rated for 24 mA)
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*** 0.125 W resistor (3.3V output through 249 ohm resistor with output shorted to ground is 0.044 W)
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* Card has input buffer stage
 
* Schmitt Trigger Input
 
* Schmitt Trigger Input
 
* 3.3V, 250 Ohm resistors (/5) for 50 Ohm output
 
* 3.3V, 250 Ohm resistors (/5) for 50 Ohm output
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== Test ==
 
== Test ==
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* Manual or Automated test methods
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=== Manual Test Method ===
  
 
* Supply Vcc 3.3V to 5V and ground
 
* Supply Vcc 3.3V to 5V and ground
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** Should be 1/2 of Vcc with 50 Ohm terminator
 
** Should be 1/2 of Vcc with 50 Ohm terminator
 
** Should be Vcc without terminator
 
** Should be Vcc without terminator
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=== Automated Test Software Method ===
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[[File:DRIVE50_P1080485-720PX.jpg]]
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==== Setup ====
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* [[QTPy49]] or [[QTPy49-01]] card
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* [[QT Py (RP2040_based)]] card
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** Analog cable
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** GVS Cable to A1
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** Analog in (BNC) to A0 on [[QTPy49]]
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* [[MyMenu]] card
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* Power card options
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** Connect USB-C to the [[QT Py (RP2040 based)]] or
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** Power from 9-12V to DC jack
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* Terminator - dependent on build option
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** 50 Ohms
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** 75 Ohms
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* Unit Under Test (UUT)
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* [https://github.com/land-boards/QT-Py/blob/main/CircuitPython/lbcards/PulseGen/PulseGen_DRIVE50_Test.py PulseGen_DRIVE50_Test.py]
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** Test software for [[PulseGen]] and DRIVE50 cards
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*** Auto-detects card type
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** Stored as code.py on [[QT Py (RP2040 based)]] to auto-run
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==== Procedure ====
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 +
* Connect 3 pin power cable to card
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* Connect BNC T to output of card
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* Connect BNC female from tester to BNC T male
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* Install 50 terminator to other side of BNC T
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* Connect USB C cable
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* Display will show
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 +
<pre>
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PulseGen/DRIVE50 V1.1
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50 Ohm card
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Set/Got Low
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Term High = OK
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</pre>
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* All 3 LEDs are on
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== Application Example ==
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 +
=== GPS Frequency Standard ===
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[[file:GPS_Freq_Std_P18490-720px.jpg]]
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* [[GPS_Frequency_Standard|GPS Frequency Standard]]
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* Card takes in PPS signal out of GPS module and drives 50 Ohm, 10 MHz Frequency Standard output on coax via BNC connector
  
 
== Mechanicals ==
 
== Mechanicals ==

Latest revision as of 11:25, 20 August 2022

Tindie-mediums.png

DRIVE50 P1080480-720PX.jpg

50 Ohm Driver Card

  • "TTL" Level Line driver
  • 50 or 75 Ohm output impedance
  • BNC or SMA output connector
  • 10K pull-up on input
  • Card is non-inverting
  • 1.5V-5.5V power
    • Typically 3.3V or 5V
  • 3-pin right angle 0.1" pitch input connector
  • (4) 4-40 mounting holes

Driver

  • 5x paralleled 74AC14 drivers
    • 24mA per pin max current output
      • Symmetric high-low drive levels
    • Short-circuit proof
      • 5V, 250 Ohms to ground is 20 mA (pins are rated for 24 mA)
      • 0.125 W resistor (5V output through 249 ohm resistor with output shorted to ground is 0.1 W)
      • 3.3V, 250 Ohms to ground is 13.2 mA (pins are rated for 24 mA)
      • 0.125 W resistor (3.3V output through 249 ohm resistor with output shorted to ground is 0.044 W)
  • Card has input buffer stage
  • Schmitt Trigger Input
  • 3.3V, 250 Ohm resistors (/5) for 50 Ohm output
    • Normal output = 10 mA per pin

Test

  • Manual or Automated test methods

Manual Test Method

  • Supply Vcc 3.3V to 5V and ground
  • Input is pulled up to Vcc
  • Measure output with BNC T
    • Should be 1/2 of Vcc with 50 Ohm terminator
    • Should be Vcc without terminator

Automated Test Software Method

DRIVE50 P1080485-720PX.jpg

Setup

Procedure

  • Connect 3 pin power cable to card
  • Connect BNC T to output of card
  • Connect BNC female from tester to BNC T male
  • Install 50 terminator to other side of BNC T
  • Connect USB C cable
  • Display will show
PulseGen/DRIVE50 V1.1
50 Ohm card
Set/Got Low
Term High = OK
  • All 3 LEDs are on

Application Example

GPS Frequency Standard

GPS Freq Std P18490-720px.jpg

  • GPS Frequency Standard
  • Card takes in PPS signal out of GPS module and drives 50 Ohm, 10 MHz Frequency Standard output on coax via BNC connector

Mechanicals

DRIVE50 MECHS REV1.PNG

Assembly Sheet

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