The TL783 is a variable three lead mains voltage regulator chip having an output range of 1.25 V to 125 V and a DMOS output transistor which is able to handle in excess of 700 mA current.
High Voltage Specification
It is specifically configured internally for working with high-voltage applications where ordinary bipolar voltage regulators become useless.
High grade performance specifications, much enhanced than most bipolar regulators are implemented through a hi-breed circuit network and sophisticated layout technology.
In this innovative regulator device, the TL783 integrates the standard bipolar circuit technology with high-voltage double-diffused MOS transistors on one chip, to create a device attributed with properties for enduring higher voltages far higher than traditional 78XX bipolar integrated circuits.
Due to the inability of secondary-breakdown and thermal-runaway situations inherently common with bipolar devices these become quite vulnerable to high voltages, unlike these the TL783 ensures full overload protection even under extreme operating conditions ranging up to 125 V across input to output.
Built-in Current Limiter
The chip also includes an in-built current limiting feature, a safe operating area safeguard and also a thermal shutdown feature.
In a worst case even if the ADJ gets isolated accidentally, all the above protection features stay functional.
The IC can be initiated and made functional just by adding a couple of external passive components. An input bypass capacitor becomes only essential in case the DC supply source is fetched from beyond 6 inches from the IC.
The IC also exhibits excellent response to sudden output short circuits and sudden voltage spikes or transients.
Circuit Diagram
WARNING: PLEASE REMOVE THE 100uF/250 CAPACITOR FROM THE INDICATED POSITION AND PLACE IT ACROSS THE OUTPUT TERMINALS OF THE CIRCUIT, THIS WILL ENSURE THAT THE 120V INPUT DOESN'T GET TRANSFORMED INTO A DANGEROUS 160V PEAK AND DAMAGE THE IC.
THE GROUND SYMBOLS SHOWN WITH THE NEGATIVE LINE OF THE ABOVE CIRCUIT SHOULD NOT BE MISTAKEN WITH "EARTHING" OF THE 3-PIN SOCKET. THE GROUND SYMBOLS ARE ONLY FOR HIGHLIGHTING THE NEGATIVE LINE OF THE BRIDGE RECTIFIER.
CAUTION: THIS CIRCUIT IS NOT ISOLATED FROM MAINS AND THEREFORE IS EXTREMELY DANGEROUS TO TOUCH WHILE POWERED AND IN AN UNCOVERED SITUATION.