{{fa>pencil?32}} In order to get a constant (lower) voltage from an higher voltage input or a source with a broader spread of the voltage (e.g. a battery) often linear regulators are used. One example could be to get $5V$ from the car battery voltage (between $11V...14V$) for a microcontroller in a control unit e.g. the brake control unit. Linear regulator here means that a transistor as a variable resistor is used to drop the unwanted voltage. Below, two types of such a linear regulator are shown - The first simuation shows a simple series regulator with a FET. "Series" here marks the fact that the transistor is in series to the load resistor $R_L$. The zener diode $D$ has a current limiting series resistors $R_D$ ahead. By the voltage divider of $R_D$ and $D$, a relatively constant voltage will be created. - The second simulation shows a more sophisticated circuit. Here, there is a feedback from the output of the transistor back to the transistor controlling voltage. This feedback is given by $R1$, $R2$ and the operational amplifier. Tasks * In both simulations there are two sliders on the right-hand side: \\ - //Input Voltage//, which changes the ingoing voltage between $5V...20V$ \\ - //Load Resistance//, which changes the load on the output between $10\Omega...1k\Omega$ \\ Play with these sliders and look for the differences! What are these? * The lower simulation with the operational amplifier is also called "**L**ow **D**rop**O**out" (**LDO**). The dropout is the minimum voltage difference on the transistor. How can the terminology low dropoff can be explained? * To which primitive OpAmp circuit does the LDO circuit ($R_1$, $R_2$ and OpAmp) look similar to? \\ How can the controlling of the transistor input voltage $U_GS$ be explained? * Given a load resistor of $R_L=1k\Omega$, an input voltage $U_I=20V$ and an output voltage $U_O=5V$, what is the dissipated power on the load and on the transistor? * One LDO is the [[https://www.ti.com/lit/ds/symlink/tps746.pdf|TPS746]]. \\ - What is the Pin $FB$ for? \\ - How does the [[https://www.ti.com/lit/ds/symlink/lm340.pdf|LM7805]] differ with view onto setup in a circuit? {{url>https://www.falstad.com/circuit/circuitjs.html?running=false&ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxAWwpABYqEBTAWjDAChtC8Rs1xiUPPmm6QobAE7gaNfoLAzwKUcngdZALwYA7BhKYZoRKFFjxIpS1eukTKaF0IJl2PFhCHj7ACbTZy7gVZMAEQQS1dfU9CNgBzPzC8QMVcWTFINgAlBLBlEDwxXJUxGjE+dNMENgB3HLzUpVEank5G2jBCNozObmdAvIQMTqKTDNqaDra+rskKPJHpzEFCtXjFjEFphvTmoLkhQtCMgDMD-d5CvNLwaCQYSBQ2AA8QMnAncAV37n9ZTOfPoEMEgwLhwBgfuBuAARAHETooRSsKiI8i-ECwl4IQgQEK9CFhSAQdH-LEEQm9UIoVi0KEgAAybAA9rTCGl2mAyuloBAyrTsMyPCA2SYJpzCaZcWEhQLXLSxEg+ABJbQABwArgAXAA6AGcAGpMgA2moAhrEGBxuMQTOLOXAGUzTd49ZkGLqAJa6s3aADGlqAA noborder}} {{url>https://www.falstad.com/circuit/circuitjs.html?running=false&ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxAWwpABYqEBTAWjDAChtC8Rs1xiUPPmm6QobAOa0whECjzcaMnpBpRxAJ2mz5i5ShpixYeHDZalOw9vDz1J02wDuNg2JQG51yM7meRfmpu4i5gNGpgGLJgAuBRmuDhcdFJYHbGpj7YagBeDAB2DBpMKNCETNwQMJmktXX1pOqlXIQI8th4WDTEYB1yZeBsACaJQQqjyXIgeYXFzRWSE7oTuGpGbABKE2nceMbp6tZ8RlDQCL5hEXartqK+2Jy3NjvinNxtlXYI8S-rLpZPD5PHxaIEvIGYQQZMxSCEYQRAm7rACGgX4gl4xlixHASBYSAcpn6CFY8OIkF6GAQ5OID2JrD2vUoNBJkFayEcoVikR0nh54gAZkIsRi+C9rGAzqdICg2AAPCh4IJpCjEZVICLcAAy8oohCoaARezkkA1XhAG11NAIJsE3UEaDNYEqVsIEBidowlWIZs8loV1vc8No5LkVNo4G4soD1LkhE9OnZQTU-vAYTi7qIcTUmpAABFdbTwG608ZCDnzamiyhHqx3Ngccn82wAPbIEDlw51k2nKpTEw8VvgKidsRKAcDmDu-tUbAcSonHRiABqLYANgAXZESBjz3H2aFiDYMADOAEsT1v8gBjXdAA noborder}}