Circuits & Schematics - Supply - 3

There’s been a lot of interesting conversation and DI teamwork lately devising circuits for ON/OFF power control using inexpensive momentary-contact switches (See Ref. 1 Ref. 4 ). Most of these designs have incorporated edge triggered ...

A stable voltage from an input supply that is higher and lower than the output is often required. A common solution is to use a boost converter followed by an LDO as shown in Figure 1. The boost converter is configured to accept voltages ranging ...

It’s remarkable how many switching regulator chips use the same basic two-resistor network for output voltage programming. Figure 1 illustrates this feature in a typical (buck type) regulator. See R 1 and R 2 where: Quantitatively, the V ...

This design idea reprises another “1 A, 20 V, PWM controlled current source” ( Ref. 1 ). Like the earlier circuit, this design integrates an LM3x7 adjustable regulator with a PWM DAC to make a programmable 20 V, 1 A current source. It ...

Rheostats Rheostats are simple and ubiquitous circuit elements, usually comprising a potentiometer connected as an adjustable two terminal resistor. The availability of manual pots with resistances spanning ohms to megohms makes the optimum choice ...

This design idea revisits another: “PWM power DAC incorporates an LM317” ( Ref. 1 ). Like the earlier circuit, this one implements a power DAC by integrating an LM317 positive regulator into a mostly passive PWM topology. It exploits ...

This design idea (DI) takes an unusual path to a power-handling DAC by merging an upside-down LM337 regulator with a simple (just one generic chip) PWM circuit to make a 20-V, 1-A current source. It’s suitable for magnet driving, battery ...

Short-circuit protection is an obvious requirement for a power supply, especially when its load connects to a cable that's subject to damage. Many modern power-converter ICs include some means of protection, such as thermal shutdown, against ...

Figure 1 shows an example of on/off circuitry commonly used in battery-operated devices. The p-channel MOSFET, Q 1 , serves as a power switch. When you push the On button, S 1 , Q 1 ’s gate goes low. Q 1 turns on and supplies battery voltage ...

For the heating and cooling elements common in industrial systems, resistance is not a fixed quantity. These elements include such devices as positive-temperature-coefficient heaters and thermoelectric coolers. Their resistance can change more than ...