CN0370 is a complete single-supply, low noise LED current source driver controlled by a 16-bit digital-to-analog converter (DAC). The system maintains ±1 LSB integral and differential nonlinearity and has a 0.1 Hz to 10 Hz noise of less than 45 nA p-p for a full-scale output current of 20 mA.

AD5542A is a single supply, 16-bit, serial input, voltage output DAC that is used to control the voltage to current conversion. ADA4500-2 is a single supply, dual low power amplifier with no zero-crossover distortion offering high linearity over the full, rail to rail common-mode input range. ADA4500-2 is used to buffer the reference voltage of the DAC and is also used in a buffer configuration to convert the voltage output of the DAC into current. ADR4525 is a high precision, low power, low noise voltage reference that is used to provide precise 2.5V reference voltage for the DAC.

This user guide will discuss how to use the EVAL-SDP-CB1Z, SDP-I-PMOD and the evaluation software to be able to write and collect data from EVAL-CN070-PMDZ. The evaluation board has provisions to read the output voltage of the DAC and an option to use an external supply voltage for the LED.

• PC with a USB port and Windows XP or Windows Vista
  • 32-b(it), or Windows 7 (32-bit)
• EVAL-SDP-CB1Z SDP evaluation board
• PMD-SDP-IB1Z interposer board
• EVAL-CN0370-PMDZ circuit evaluation board
• CN-0370 evaluation software:
  • ftp://ftp.analog.com/pub/cftl/CN0370/
• Power supply: 6 V wall wart.
• Agilent 34401A Multimeter or equivalent.
• A GPIB-to-USB cable (Required only when taking linearity tests for the circuit).

• Connect the 120-pin connector J4 on the PMD-SDP-IB1Z interposer board to the connector marked CON A on the EVAL-SDP-CB1Z (SDP) evaluation board. Shunt on JP1 to be place on the +5.0V configuration.

• Connect the EVAL-CN0370-PMDZ to the PMOD connector J3.

• Connect a +6V wall wart supply to the connector J1 of the interposer board.

• The USB cable is used to connect EVAL-SDP-CB1Z to the PC.

• LED_SUPPLY is the supply for the LED. It can be taken from the PMOD supply or an external voltage supply,VEXT. It is shorted by a shunt to PMOD by default.
• Test point VCC and AGDN are used to take voltage measurements.
• VEXT is used to supply an external voltage to the LED supply (Input range: +20max).

• Extract the file CN0370_Evaluation_Software.zip and open the file setup.exe

• Click Next to view the installation review page

• Click Next to begin the installation

• Upon completion of the installation of the CN-0370 Evaluation Software, the installer for the ADI SDP Drivers will execute.

• Click Next to set the installation location for the SDP Drivers

• Press Install to install the SDP Drivers and complete the installation of all software. Click Close when done.

1. Write data
   • This button is used to write the data into the DAC
2. Input Mode
   • This is a selector where the user can choose the input mode of changing the amount of current or changing the actual DAC code being written
   • Input Current Mode- the amount of current desired for the LED is adjusted and by pushing the Write Data button writes the data into the board.
   • Input Code Mode- the exact code is written on the Code box, and the amount of current output is automatically adjusted by pushing the Write Data button.
3. External Resistor
   • Enable the external resistor if the resistor on R_LIMIT has been changed
4. Iout
   • This control will enable the user to change the amount of current flowing through the LED
5. R_limit
   • This is the value of the resistor that limits the amount of current through the LED, it is set to a default value of 124?

1. If the external resistor is replaced, enable the External Resistor button and write new value for the R_Limit.
2. Select Input Current Mode.
3. Adjust the amount of desired current by using the slider or the text box.
4. Push the Write Data button to write the code to the board.

1. If the external resistor is replaced, enable the External Resistor button and write new value for the R_Limit.
2. Select the Input Code Mode.
3. Write the exact code to be written in the Code text box.
4. Push the Write Data button to write the code to the board.

End of Document