19v dc regulation circuit diagram

thanks for your replies in my previous thread posted, i really appreciate. pls., how do i, and what circuit diagram should i use to convert a 24v dc battery to 19v dc supply

You need to use a dc to dc converter

snazzy c said:

thanks for your replies in my previous thread posted, i really appreciate. pls., how do i, and what circuit diagram should i use to convert a 24v dc battery to 19v dc supply

Click to expand...

You didnt mention your "Current" requirement. For simple, you may use a LM7818 regulator which will naturally regulate the 24 volts to 18 volts. Inserting two 1N4007 Diodes in series between the centre pin to GND will boost the output to 19.2V which is acceptable. If you aim accuracy, other option is using a LM317. But depending on current required, you may have to use good heat sinks in both cases.

You can use this calculator to vary the value of the program resistor (R1) and output set resistor (R2) and calculate the output voltage for the LM317 / LM338 / LM350 family of three terminal adjustable regulators. This calculator will work for most voltage regulators with a reference voltage (VREF) of 1.25. Typically, the program resistor (R1) is 240 ohms for the LM117, LM317, LM138 and LM150. For the LM338 and LM350, 120 ohms is typically used. However, other values such as 150 or 220 ohms can also be used. Refer to the adjustable regulator datasheets below for more information.

You can also search using Google for LM317 calculator, here is one for example

LM317 Voltage Calculator - Electric Circuit

Alex

for the 19v dc regulation supply, the current requirement of the device to be powered is 3A. but am affraid the dc battery source i used is having 24v, 100Ah. will it blow up the device

snazzy c said:

for the 19v dc regulation supply, the current requirement of the device to be powered is 3A. but am affraid the dc battery source i used is having 24v, 100Ah. will it blow up the device

Click to expand...

Hi,
for a 19V 3A Supply, if you use any linear regulator, you must have a very good heat sink , because your regulator have to dissipate 15Watts. for a 3A Linear Regulator (something Like LM317 , but higher Current), i recommend LT1083 (7.5A) or LT1084 (5A). See their Datasheets, they have simple schematic for start.

Because High Power Dissipation that you will face , i recommend using a Step-Down Switching Regulator. Something Line LM2676(3A) or LM22673(3A) or LM22678 (5A) or LM22679 (5A).

because your current requirement is 3A, I'll go with 5A Regulators to be on the Safe Side. Check Their Datsheets, they have various capabilities , Like Integrated (may be adjustable) Current Limit , Soft-Start , ...etc. In their Datasheets , you will find reference circuit schematics.

snazzy c said:

for the 19v dc regulation supply, the current requirement of the device to be powered is 3A. but am affraid the dc battery source i used is having 24v, 100Ah. will it blow up the device

Click to expand...

The current at the input must be naturally more than the current required at the output. Thus no matter you power the input with 10 Ah or 100 AH it will not matter if you draw just 3amps at the output. The voltage level will certaintly affect the circuit. Mean if you need 19 volts and you cant power the regulator with 40 or 50 volts as 30 or 35 volts is the max limit of the device. But you have 24 volts which is quite safe.
Anyways, as you have mentioned, your requirement as 3 amps, you may use LM317 To220 package with Boost current circuit as shown in the pic. More application diagrams may be refered on the device datasheet.