19V at 5A

 I have a 24volt supply that I want to reduce to 19volts, the circuit needs to be able to carry 4A current so I’m using the LM338 which can carry 5A. What size resistors should I use to get the 19v required and be able to carry the 4 Amps? by MeElec May 28, 2019 Add comment... Please sign in or create an account to comment.

 Please read the datasheet of LM338 (from digikey.com). You just use its typical application circuit of figure 15. You can assume R1 = 270 ohm, then calculate the R2 from the formula. The current passing resistors is 4.6mA, so the power of resistors can be 0.1W. The 4A will cause the LM338 a large heat: the voltage drop is 24-19 = 5V, P = 5Vx4A = 20W, so you need to add a big cooler for 20W if the current is continuous. +1 vote by wangwg88 May 28, 2019 Add comment... Please sign in or create an account to comment.

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