January General Description. The DS is comprised of seven high voltage, high cur-. All units feature com-. To maximize their effec-. The DS has a series base resistor to each Darlington.
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I need to know what formulas or set of calculations would be used to figure out the base resistor and load resistors when hooking up a darlington pair as my datasheet for the ds does not provide a hfe. The chip is 7 darlington pairs, and I am hooking it up to be controlled by my micro controller, to drive leds. If I know the current I need for my led to be saturated, how would I know what base resistor value I would need to put on the inputs to keep the base current under 25mA.
Essentially I want to know what formulas are used or what is the common practice for designing such a circuit led driver. Single transistor calculations seem to be well published and I always have a hfe to work with but this is missing from the datasheet for these darlington drivers. The DS already has series and shunt base resistors that are okay up to 5V input, and should be fine down to much lower inputs. As Sphero indicates, these things already have appropriate resistors internally to allow them to be driven by 5 volt logic levels I suspect they are ULN's in disguise.
Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. How do you perform circuit calculations for the darlington pair Ask Question. Asked 5 years, 10 months ago. Active 5 years, 10 months ago. Viewed 1k times.
If I know the current I need for my led to be saturated, how would I know what base resistor value I would need to put on the inputs to keep the base current under 25mA Essentially I want to know what formulas are used or what is the common practice for designing such a circuit led driver Single transistor calculations seem to be well published and I always have a hfe to work with but this is missing from the datasheet for these darlington drivers.
Active Oldest Votes. Spehro Pefhany Spehro Pefhany k 9 9 gold badges silver badges bronze badges. This is great news. However in terms of darlington pairs in general, say if I was to design a custom darlington circuit using individual transistors is there a calculation used. The DS allows for 1. The 7. In the case of the DS its 83uA and uA the main output transistor is driven by the other transistor so the base resistor can be less without affecting the required input current.
Peter Bennett Peter Bennett I would still like to know about doing calculations in the future should I build a darlington pair from scratch but since I was not very clear in my post and made reference to the DS that I am using this is an appropriate response.
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Datasheet Texas Instruments DS2003
High Current/Voltage Darlington Driver