# Circuit design for power cut help.....

Discussion in 'General Electronics Chat' started by edliu, Feb 23, 2011.

1. ### edliu Thread Starter New Member

Feb 22, 2011
11
0
Hi All,

I have designed a circuit that takes in power from a battery pack. (~51V and nominal operating voltage is 48V). I have to step down to 27V @ 4A, 5V @ 6A, 24V and lastly 48V.

I have attached a design of my circuits. I used two 5V regulators and connect them in parallel with the output connected in series to get the max combined current, a 28V regulator and did a voltage divider to get 27V and then using a transistor to increase the current. To get 48V, i just did a parallel connection to the battt pack. Please see attached PDF.

As I am new to such designing of circuits, i will appreciate help and advise. Please kindly see my circuit and advise how I can improve it.

http://www.mediafire.com/file/u18fu6xzuplc2s3/Sheet1.pdf

2. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
You should attach the PDF file to your original post. Edit your post, use the "Go Advanced" and "Manage Attachments" buttons, then select the file to upload from your computer.

You show the 48v battery connected with the negative terminal on the top. When drawing schematics, it is preferred to have more positive voltages towards the top of the schematic, and more negative voltages towards the bottom.

C2's lower terminal is not connected.

If you meant for the battery to be connected with the negative terminal on top, then everything to the right of IC "TEN 100" has their power/ground terminals reversed.

If you meant for the battery to be connected with the positive terminal on top, then IC "TEN 100" has its' Vin- and Vin+ terminals reversed.

Datasheet for the Traco Power TEP 100-4816:
The SENSE inputs wouldn't detect what the voltage across the load is, because you have not connected them across the output, so the 100-4816 will output maximum voltage that will not be regulated.

R1/R2/R3/TIP2955 serve no useful purpose, unless you need to generate heat. They will cause you to get wildly erratic output.

I don't know why you are paralleling the outputs for the 5v output. You should select a single DC-DC converter that is capable of the output current necessary. R4 and R5 will cause the output to have poor regulation.

The LM150/LM350 is a very old linear regulator, and is not very efficient.

3. ### edliu Thread Starter New Member

Feb 22, 2011
11
0
Dear SgtWookie,
Referring to my question on power cut as seen below:
padon me as I am a newbie, How do you actually regulate the 100-4816. I used R1 and R2 is because I thought of using the voltage divider rule. I want to actually get a 27V output in stead of a 28V output. The TIP2955 was because of boosting the current up to 3A for the 27V output voltage after the voltage divider resistors or R1 and R2.

The DC-DC 5V was in series because of trying to get 5A maximum current. If you do not suggest that this is a good way of doing so, is there any circuits or device that you can recommend me?

• ###### Sheet1.pdf
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108.9 KB
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11
Last edited: Feb 27, 2011