By Jerry Steele, September 15, 2003
For maximum reliability, cooling-fan speed should be based on current rather than temperature. Commonly available thermal-sensing fan-control ICs require elevated temperatures to start fans, and even higher temperatures to turn them on harder. In...
By Jerry Steele, May 26, 2003
While current-shunt-monitor ICs like the INA168 can be connected to current-shunt resistors at supply voltages of up to 60 V, the circuit shown in the figure allows current sensing at even higher voltages....
By Jerry Steele, March 04, 2002
Before the MAX6629/30/31/32 series of temperature sensors were available, all digital-output temperature sensors were I2C (alternatively called SMBus) sensors that had to be written to for addressing, before they were read. Prior SPI...
By Jerry Steele, May 07, 2001
Using an analog temperature sensor, an op amp, a transistor, and a low-dropout linear regulator, this circuit provides a 4-to-20-mA output over a 3.75- to 28-V compliance range (see the figure)....
By Jerry Steele, September 05, 2000
In low-cost systems where inexpensive fans are used with no fan control, fan-failure detection is particularly useful. Fans running full-time use up their operating life more quickly than those...
By Jerry Steele, July 10, 2000
This Idea For Design was originally published March 6, 1995. Positive feedback along with a series output resistor can provide a controlled output impedance from an op-amp circuit, with lower losses than would result from using an...
By Jerry Steele, June 26, 2000
Galvanic isolation of sensors, such as temperature sensors, is required since these sensors are often mounted in "mechanically inconvenient" locations. "Mechanically inconvenient" often implies an electrically noisy environment, an environment where...
By Jerry Steele, February 21, 2000