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I have programmed an Arduino to control a DAC, generated signal control the current of an LED via a LT1206.

Whenever I plug in the power, before Arduino starts, the LED starts to blink because it gets the wrong signal from the DAC. How can I fix it?

(after a little time system works perfectly)

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  • \$\begingroup\$ The behavior is uncontrolled, unless you have an Enable pin on the DAC. \$\endgroup\$ – analogsystemsrf Dec 9 '18 at 12:57
  • \$\begingroup\$ I used DAC7611, I think it has no Enable pin. \$\endgroup\$ – user1482636 Dec 9 '18 at 13:33
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The LT1206 has a SHUTDOWN pin which lets you control the power-on behaviour. You can use a very simple RC-timing circuit to control the timing of this shutdown input.

Therefore, connect the shutdown input of the LT1206 with a capacitor C to the positive supply voltage of the LT1206 and with a resistor R to GND. This will delay the LT1206 upon power-up by approximately T=R*C seconds. (E.g. C=10uF, R=100kOhms leads to T=1 seconds, which should be more than enough).

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  • \$\begingroup\$ Thanks for the reply, How about the shutdown? this blinking occurs whenever the power switch off \$\endgroup\$ – user1482636 Dec 9 '18 at 13:30
  • \$\begingroup\$ For power-off, you could use a diode D across the capacitor. (Cathode to pos. supply voltage of the LT1206, anode to shutdown input of LT1206). This will only work if your pos. supply is decaying fast. We would need to see your complete circuit schematic for better advice. \$\endgroup\$ – Stefan Wyss Dec 9 '18 at 13:54
  • \$\begingroup\$ my power supply is computer power, \$\endgroup\$ – user1482636 Dec 9 '18 at 14:06

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