The post explains the technical specifications, datasheet, and application notes of the IC 78H12A which is a voltage regulator IC capable of providing a fixed regulated 12V output at maximum 5 amp current.
5 Amp Regulator Specifications
We are familiar with the popular 78XX ICs such as the 7812 IC which can produce 12V fixed voltage at its output with input supplies anywhere from 15V to 24V.
However the above device is capable of handling at the most 1 Amp of current which may be not sufficient for many standard applications.
For circuit applications which require currents as high as 5 amps, a higher rated alternative may be selected in the form of the IC 78H12A which is quite similar to its younger brother 7812 but is capable of handling up to 5 amps of current.
The main technical specifications or datasheet of this IC 78H12A may be studied with the following explanation:
The 78H12A is a three terminal linear, positive fixed voltage regulator IC rated for continuously delivering around 5 amps of current with typical fixed 12 volts at its output.
The IC is internally fully protected a against short circuits or over loads at its output which makes it highly rugged and versatile.
In an event of a short circuit or over load across its output terminals, the device instantly shuts down the supply of power across its output leads, thus inhibiting any possibility of electrical hazards. The situation also protects the IC from getting damaged.
The above feature ensures safe operations of the connected electronics and also avoids the inclusion of external safety circuits reducing the cost and the component count of the over all configuration.
The device is available in a hermetically sealed TO-3 metal package, and facilitates easy fitting of an heatsink for better efficiency and working of the device.
Main Technical Features of the IC
The main features of the IC may be summarized as follows:
- Output Voltage: 12V, fixed, regulated
- Output Current: Maximum 5 Amps
- Protections: In-built short circuit and over load protected.
- Power Dissipation: 12 x 5 = 50 to 60 Amp Approximately
- Package: TO-3 metal body
Pin Outs of IC 78H12A
The figure below shows the pinout details of the IC 78H12A, if the device is held with the pins toward us and with the larger plain section of the area upwards, the right pin is the input, the left pin is the output while the body becomes the ground of the IC.
Application Notes
The IC 78H12A is fundamentally suited for all electronic circuit application where a fixed 12V is imperative and with requirements upto 5 amp, example for driving 12V DC motors, for driving high watt white LeDs for flood lighting, and also for charging lead acid batteries (with some modifications).
The following diagrams illustrate a couple of main applications which may be implemented with this versatile 12V 5 amp fixed voltage regulator IC.
12V 50 AH Battery Charger Circuit
30 watt LED Driver Circuit
Using LM338
In case you are unable to get the above IC, you can create an equivalent 12V 5 amp fixed regulator using the following LM338 based configuration
12V 5Amp from IC 7812
In the above designs I have explained how to get 12V fixed voltage at 5 amp current from specialized IC, however the same could be easily acquired from a simple 7812 IC, through a little modification as given below.
The diodes at the center lead of the IC 7812 allows us to alter the output to any desired value that may be higher than 12V.
For example for charging a 50 Ah battery you may require 14V 5 amp, which can quickly tweaked by adding the shown diodes.
So this design is actually is quite customizable for many different 12V 5 amp applications.
For adjusting the current output, simply alter the value of the lower 1 ohm 5 watt resistor, it's as simple as that!
The indicated TIP36 will allow upto 25 A, however if you are only interested to get 5 amps, you can easily replace it with a TIP32C transistor over a heatsink.
