The brand Sparkos Labs, specialized in the design of high quality discrete electronic components, has created a range of ré discrete regulators designed to replace adjustable monolithic regulators. They are in the standard format TO-220 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 allows the integration of many internal capacitors that cannot be integrated into an integrated circuit. In addition, the discrete controller has an output decoupling capacitor on board, eliminating the need to install one externally. The error amplifier of this controller is also completely discrete, being based on a slightly modified SS3601 AOP. 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 feedback voltage to a reference voltage.
Discrete AND Small
These discrete regulators are the smallest models available on the market. They have a width of 11.4mm, 1.3mm wider than a standard TO-220 format. Due to their small size, they can be combined with narrow heatsinks or even adapt to the fixing hole of the heat sink already existing in your equipment. The tab on the top of the regulator is not covered by the PCB allowing easy mounting. The pins are placed in the same way as on a TO-2202 format controller.
To replace a monolithic regulator with a discrete model, you need to know its polarity, pin-out 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 controllers using potentiometers or voltage dividers on the ground pin to achieve the specified performance.
If a regulator to be replaced is mounted on a heat sink, the same heat sink must be used with the discrete replacement regulator. It is not necessary to use a larger heat sink. The existing heat sink will suffice. Since the tab of these discrete regulators is connected to the voltage input, electrical insulation must be used between the tab and the heat sink.
The input and output bypass capacitors of the existing circuit should also be adapted and do not require any modification for normal operation. If the output capacitor closest to the regulator is ceramic or film type, a better transient response can be obtained by removing it from the circuit, as ceramic and film capacitors degrade the phase margin of the device. In cases where the output capacitor is removed from the circuit, the 10uF internal tantalum polymer capacitor will be sufficient as an output capacitor, and the device will operate with a higher phase margin and a less transient response.
The best transient response can be obtained by using a Panasonic EEU - FR1H101B electrolytic capacitor (100μF 50V 65mΩ ESR) as the output capacitor. This capacitor can be used to replace the existing output capacitor or it can be added in parallel. It should be noted that the correct polarity must be observed when installing these electrolytic capacitors.