By Michael Score, Texas Instruments Switching power supplies are used in almost every end-equipment that needs a long battery life, low heat generation, or to meet ENERGY STAR® guidelines. When designing a switching power supply, it is difficult to decide which output capacitor type to use. Electrolytic capacitors have high equivalent series resistance (ESR), making […]
FAQ
Basics of cooling transistors, IGBTs,
and power FETs with heat sinks and PCBs
By Chris Francis When designing any electronics that consumes a significant amount of power you need to consider where that power is going to go. With power electronics –such as IGBTs, power FETs, or power transistors — you might be expecting most of it to end up in your load but there will be some which doesn’t. Even […]
Choking off EMI/RFI in off-line switchers
by Jim Earley, President, Premier Magnetics Electromagnetic interference (EMI) and radio frequency interference (RFI) are natural byproducts of switching power supplies. Much of this noise arises as a direct result of the large voltage swings caused by short-duration charging and discharging in the power supply circuitry. Common mode noise, which is generated through the power […]
Understanding op amp input stages
Choosing an op amp and getting the best out of it involves some understanding of what is inside the chip, particularly the input stage. Simple bipolar input stage A conventional bipolar opamp will usually have a long-tailed-pair with two NPN or PNP input transistors as shown below. This explains the limited working range of a […]
MOSFET Drivers – what are they and why do we need them?
There are a lot of MOSFET drivers around these days. MOSFET drivers often contain MOSFETs themselves. There are several reasons for needing MOSFET drivers: Drive current – MOSFETs can have very high gate capacitance. For example, the IRF530NS from International Rectifier is a 90mW device which can withstand 17A continuous drain current at 100V and […]