The Sparkos Labs brand, which specializes in the design of high quality discrete electronic components, has created a range of discrete controllers to advantageously replace adjustable monolithic controllers. They are in the standard TO-220 format with 3 pins and have a fixed voltage with more than 1A available at the output.
Why discrete regulators ?
These discrete voltage regulators will outperform all TO-220 monolithic regulators in terms of output noise, transient response and load regulation. This discrete design makes it possible to integrate many internal capacitors that are impossible to integrate in an integrated circuit. In addition, the discrete regulator includes an output decoupling capacitor, eliminating the need to install one externally. The error amplifier of this regulator is also fully discrete, being based on a slightly modified AOP SS3601. The internal reference voltage is a precision shunt reference with post RC filtering, allowing extremely low noise. In this design, the error amplifier compares a return voltage to a reference voltage.
Discrete & Small
These discrete regulators are the smallest models available on the market. They are 11.4mm wide, 1.3mm wider than a standard TO-220 size. Due to their small size, they can be combined with narrow heatsinks or even fit into an existing heatsink mounting hole in your equipment. The tab on the top of the controller is not covered by the PCB, allowing easy mounting. The pins are placed in the same way as on a TO-220 controller.
Replacing a regulator
To replace a monolithic regulator with a discrete model, you need to know its polarity, pinout and output voltage. In the case of an adjustable regulator, its output voltage is fixed by the circuit in which it is integrated via a resistor that must be short-circuited and removed.
It is not recommended to attempt to dynamically adjust the output voltage of these discrete regulators using potentiometers or voltage dividers on the ground pin to achieve the specified performance.
If a controller to be replaced is mounted on a heatsink, the same heatsink must be used with the replacement discrete controller. It is not necessary to use a larger heatsink. The existing heatsink will suffice. Since the tab of these discrete regulators is connected to the voltage input, an electrical insulator must be used between the tab and the heatsink.
The input and output shunt capacitors of the existing circuit should also be adapted and require no modification for normal operation. If the output capacitor closest to the regulator is of the ceramic or film type, a better transient response can be achieved by removing it from the circuit, since ceramic and film capacitors degrade the phase margin of the device. In cases where the output capacitor is removed from the circuit, the internal 10µF tantalum polymer capacitor will be sufficient as the output capacitor, and the device will operate with a higher phase margin and a less transient response.
The best transient response can be achieved by using a Panasonic EEU - FR1H101B (100µF 50V 65mΩ ESR) electrolytic capacitor as output capacitor. This capacitor can be used to replace the existing output capacitor or it can be added in parallel. Please note that the correct polarity must be observed when installing these electrolytic capacitors.