Switching Vs. Zener controlled supply Switching Vs. Zener controlled supply LucasBS (Mechanical) (OP) 15 Jul 16 01:07 What are the pros an cons of a Switching mode power supply Vs. a zener controlled power supply (also known as emitter follower voltage regulator) ? Everyone knows the first one. Here's a picture of the second one: http://www.radio-electronics.com/info/data/semicon... RE: Switching Vs. Zener controlled supply VE1BLL (Military) 15 Jul 16 01:35 Switching is typically more efficient. This is because the switching device is either on (low voltage drop, thus low power dissipation), or off (no current, thus low power dissipation). In contrast, the linear regulator uses voltage drop over the transistor to control the output voltage. So high current and voltage drop at the same time, power dissipated as heat. RE: Switching Vs. Zener controlled supply ScottyUK (Electrical) 15 Jul 16 05:14 Linear supplies are inherently quieter, whereas switchers can be made fairly quiet through careful design. RE: Switching Vs. Zener controlled supply OperaHouse (Electrical) 15 Jul 16 14:20 Zener based supplies are becoming rare these days. They are neither accurate because of transistor gain or zener tolerance. They can easily be replaced by a single part of the 78XX type that are offered in a variety of voltages and currents. They can also be adjusted to any voltage above the base voltage by the addition of two resistors. Low drop out varieties also allow a smaller differential between input and output voltages. If going the zener route, consider using a LM431 as a replacement for the zener. Last couple hundred I bought only cost about 3 cents each. RE: Switching Vs. Zener controlled supply Skogsgurra (Electrical) 15 Jul 16 18:43 Of course, switchers are more efficient. But efficiency is not everything. For low power applications where you need a measly few hundred microamps at 3.3 V or so, a zener supply is OK. Even if you need one mA with occasional short pulses of higher current. And, yes, the LM431 is great. Doesn't cost much, is stable and low noise (which you can't say about zeners) and can easily be made to deliver any voltage at or above base voltage. Gunnar Englund www.gke.org -------------------------------------- Half full - Half empty? I don't mind. It's what in it that counts.