Hello , I need to supply several amplifier with 3V 3.3V 5V 10V
5V supply is needed for several amplifers in total 500mA
Is there some variable high current that can supply 1A (would be great) reference voltage device.

I know TL431 its great with variable voltage and low noise but it can only supply at most 100mA.
is there a similar stronger device which could be used as negative and positive variable reference with current at least 1A?
Thanks.

 

How low is "low noise"?

is there a similar stronger device which could be used as negative and positive variable reference with current at least 1A?

Why a negative voltage?
You only list positive voltages in your first sentence.

Do you need several voltages at once, or just one voltage that can be varied?

 

Hello crutshow,I need -5V for the switch described below.
And yes I need some positicw variable voltage regulator device which could bias RF amplifiers.
Is there some recommendations?


https://cdn.macom.com/datasheets/MASW-008322.pdf

 

I know TL431 its great with variable voltage and low noise but it can only supply at most 100mA.

yes, max 100mA on its own... but you can add a transistor and this way it is easy to handle 1A or more.

 

and negative voltage is easy too. just move series resistor to the other supply rail:

 

Hello, There is a power consumption consideration.I need to supply in parralel several amplifiers with with total current of 0.54A.
I intend to convert 12V input to 5V output so my device has (12-5)*0,5=3.78W threw it.
Suppose I will try to use 595-TLV76150DCYR
How can I know that the power which will flow threw this device wont burn it?
I have found something that could help shown in the photo below, but I am not sure what number s to use?
How do I calculate the expression in my case?
Thanks.


https://www.mouser.co.uk/ProductDetail/Texas-Instruments/TLV76150DCYR?qs=Jm2GQyTW/bii1Rd2R0M2bQ==
https://www.ti.com/lit/ds/symlink/tlv761.pdf?ts=1755083747176&ref_url=https%3A%2F%2Fwww.ti.com%2Fproduct%2FTLV761

 

UPDATE:
As you can see bellow,IF I use one TLV761 to supply all the amplifiers it will burn.
Is there a way to distribute several regulator in parralel ? what things i need to be carefull of?
Thanks.

 

so now you are changing from shunt to series regulator. assuming you are looking for linear regulator to avoid any interference, options include dropping that 12V to something more suitable such as 7-8V or use separate regulator for each of the loads or use higher power regulator or use circuit that shifts power dissipation from regulator to something beefier like external transistor (something that can have heatsink).
another possibility is to use classic voltage regulators since they do have a protection and will shut off if thermal limit or current are exceeded. this will protect the regulator but stop circuit. you can also check what regulators are used on those lego style products.

 

Hello , I prefer to use a linear regular device to power my 5V amplifiers.
I have 6 amplfier which need 5V, the tottal current that they consume is 0.54A.
So If My DC input is 12V and output is 5V then the "device" needs to wistand 3.78W, Which could heat up a regulator.
What regulator you reccomend me to use in this situation so it wont get burned?
maybe several in parralel?
Thanks.

 

Hi yef,
Which type of 5Vreg are you trying to use?

One simple method that would limit the dissipation of a regular 7805 to, say 2 Watts, would be a pre 7809 ot 7808 regulator.

E

Added:
https://www.ebay.co.uk/itm/36420485...mkcid=28&google_free_listing_action=view_item

 

Hello , I am building a biasing system for RF amplfiers so I prefer to use regulators with as low noise as possible ,thats why I prefer to use linear regulator and not DC-DC(unless its not possible)
So if I look at the LM7805 data sheet delta_T=3.78*62=234C so I think this device would get burned.
What do you suggest to do with 7809 so its wont get burned?
How the 7809 will help us not getting 7805 getting burned?
Thanks.

 

hi yef,
Do you understand the attached graphs for the 7805?

If you have a 12V source supply which drives a 7809 or 8 ref, the 9/8v output drives a 7805 with a 0.56A load, what do you calculate the wattage on the 7809 and 7805.???

Post your calculations.

Also I posted a range of simple heat sinks that will extend the possible dissipation range.

E

 

Hello Eric,there are two things:
1.If my input is 12VDC then 7809 will have on the output 9V.
The current flowing threw this device ia 0.6A. The P=3V*0.6A=1.8W T_total=25+112=137
so delta_t=62.5*1.8W=112C which is very high and its close to 150C shutdown .

so there is a problem with this preregulator because it barely could withstand 1.8W

on the 7805 side :
Its P=(9-5)*0.6A=2.4W
So T_total=2.4W*23.9=57.36+25=82C
So based on the tables it very high temprature.

2.
Regarding the plots shown below ,I see that with heatsink it can wistand 10W whoch is totally contradicting the table calculation.
How do I make sure both of these device in series can deliver 5V and 0.6A?
without burning ?
Thanks.


https://www.mouser.com/ProductDetail/STMicroelectronics/L7809CD2T-TR?qs=15AzPhfEMg9/qG49g2z5xQ==

https://www.mouser.com/ProductDetai...Dg0QgpSqLkvuQVmaRiAZPb_zKqwUCAlEaAjjKEALw_wcB