LM7805 alternative - Page 1
Forum section: electronics / beginners

author: hpibmx
author_rank: Regular Contributor
timestamp: March 29, 2022, 02:34:44 am
content: Hi,Any recommendation for lm7805 replacement with higher amp? At least 3AmpI need exact 5v with minimum of 3A replacement.Thank you

author: jonpaul
author_rank: Super Contributor
timestamp: March 29, 2022, 02:52:13 am
content: What's the maximum input voltage, dissipation ={ Vin-Vout}x I maxsee 1970s National Semiconductor app note on use with external power transistorsIn general one uses a switching regulator rather have linear for such high power requirements.Suggest that you learn about types voltage regulators first.Bon SoiréeJon

author: pqass
author_rank: Super Contributor
timestamp: March 29, 2022, 03:03:14 am
content: See image below for what jonpaul was suggesting.Fromhttps://www.mouser.com/datasheet/2/149/LM7805-1010961.pdf

author: bdunham7
author_rank: Super Contributor
timestamp: March 29, 2022, 03:10:40 am
content: Quote from: hpibmx on March 29, 2022, 02:34:44 amJust do a search at Digi-Key or Mouser for an LDO regulator 5V >3A:https://www.mouser.com/c/semiconductors/integrated-circuits-ics/power-management-ics/voltage-regulators-voltage-controllers/ldo-voltage-regulators/?output%20current=3%20A~~7.5%20A&output%20voltage=5%20V&rp=semiconductors%2Fintegrated-circuits-ics%2Fpower-management-ics%2Fvoltage-regulators-voltage-controllers%2Fldo-voltage-regulators%7C~Output%20CurrentProbably one of the LT1084-series would work well. You do have to watch the power dissipation and heatsink issues, especially if your supply is more then 8 volts or so.

author: srb1954
author_rank: Super Contributor
timestamp: March 29, 2022, 06:33:16 am
content: Quote from: hpibmx on March 29, 2022, 02:34:44 amIf you can accommodate a TO3 package then the LM323 is suitable and it is easier to get the heat out of a TO3 package.If you have to have a TO220 package then an MC78T00 would do the trick but heatsinking is a little more difficult.

author: magic
author_rank: Super Contributor
timestamp: March 29, 2022, 07:20:34 am
content: LD1085V50. Note that it will require some minimum output capacitance for stability.Or some LM338/LM350 with two resistors.

author: mariush
author_rank: Super Contributor
timestamp: March 29, 2022, 07:29:51 am
content: The chips with 1085 in their name (they're made by multiple companies) - they're rated for 3A. There's a 5v fixed output version and there's an ADJ (adjustable) version, which allows you to set the output voltage with 2 resistors like with the LM317.Like the others say, you'll have to be aware of the amount of heat dissipated and install a proper heatsink - the chip throws away the difference between input voltage and output voltage as heat.So for example, 7v input , 5v output, that's 2v x 3A = 6 watts of heat.If you know for sure the input voltage will always be above some threshold, you could reduce the amount of input voltage the regulator receives by adding a resistor in series with the input. That way the heat will be spread across both resistor and regulator

author: Zero999
author_rank: Super Contributor
timestamp: March 29, 2022, 10:10:37 am
content: Quote from: srb1954 on March 29, 2022, 06:33:16 amUnfortunately the 78T05 is obsolete. How about he LD1085V50?

author: hpibmx
author_rank: Regular Contributor
timestamp: March 30, 2022, 05:04:35 am
content: Quote from: magic on March 29, 2022, 07:20:34 amyes found out about lm338 this help me thanks for pointing out.

author: SmallCog
author_rank: Frequent Contributor
timestamp: March 30, 2022, 09:54:41 am
content: Just run them in parallelhttps://www.analog.com/en/technical-articles/paralleling-linear-regulators-made-easy.html