Search This Blog

Thursday, July 05, 2007

LF398 - Monolithic Sample and Hold Circuit

The LF198/LF298/LF398  are monolithic sample-and-hold circuits which utilize BI-FET technology to obtain ultra-high dc accuracy with fast acquisition of signal and low droop rate.

LF398 - Monolithic Sample and Hold Circuit

Operating as a unity gain follower, dc gain accuracy is 0.002% typical and acquisition time is as low as 6 µs to 0.01%. A bipolar input stage is used to achieve low offset voltage and wide bandwidth. Input offset adjust is accomplished with a single pin, and does not degrade input offset drift.

LF398 - Monolithic Sample and Hold Circuit

The wide bandwidth allows the LF198 to be included inside the feedback loop of 1 MHz op amps without having stability problems. Input impedance of 1010Ohm allows high source impedances to be used without degrading accuracy.

P-channel junction FET's are combined with bipolar devices in the output amplifier to give droop rates as low as 5 mV/min with a 1 µF hold capacitor. The JFET's have much lower noise than MOS devices used in previous designs and do not exhibit high temperature instabilities. The overall design guarantees no feed-through from input to output in the hold mode, even for input signals equal to the supply voltages.

Wednesday, July 04, 2007

TDA5051AT - Home automation modem

The TDA5051A is a modem IC, specifically dedicated to ASK transmission by means of the home power supply network, at 600 baud or 1200 baud data rate. It operates from a single 5 V supply

TDA5051AT - Home automation modem

Transmission and reception stages are controlled either by the master clock of the microcontroller or by the on-chip reference oscillator connected to a crystal. This ensures the accuracy of the transmission carrier and the exact trimming of the digital filter, thus making the performance totally independent of application disturbances such as component spread, temperature, supply drift.

TDA5051AT - Home automation modem

Transmission mode - To provide strict stability with respect to environmental conditions, the carrier frequency is generated by scanning the ROM memory under the control of the microcontroller clock or the reference frequency provided by the on-chip oscillator

Reception mode - The input signal received by the modem is applied to a wide range input amplifier with AGC (−6 dB to +30 dB). This is basically for noise performance improvement and signal level adjustment, which ensures a maximum sensitivity of the ADC.

Tuesday, July 03, 2007

LM3914 - Dot Bar Display Driver

The LM3914 is a monolithic integrated circuit that senses analog voltage levels and drives 10 LEDs, providing a linear analog display. A single pin changes the display from a moving dot to a bar graph. Current drive to the LEDs is regulated and programmable, eliminating the need for resistors. This feature is one that allows operation of the whole system from less than 3V.

LM3914 - Versatile and Easy use Display
  • Drives LEDs, LCDs or vacuum fluorescents
  • Bar or dot display mode externally selectable by user
  • Expandable to displays of 100 steps
  • Internal voltage reference from 1.2V to 12V
  • Operates with single supply of less than 3V
  • LED driver outputs are current regulated, open-collectors

LM3914 - Dot/Bar Display Driver

The circuit contains its own adjustable reference and accurate 10-step voltage divider. The low-bias-current input buffer accepts signals down to ground, or V-, yet needs no protection against inputs of 35V above or below ground. The buffer drives 10 individual comparators referenced to the precision divider. Indication non-linearity can thus be held typically to ½%, even over a wide temperature range.

Millivolt Meter using a LM3914 LED Dot Display

Millivolt Meter using a LM3914 LED Dot Display

More Reading

Monday, July 02, 2007

Spread Spectrum and RF Resources

Spread Spectrum and RF Resources

A collection of exceptional resources that will prove useful in your spread spectrum and other wireless projects, ranging from spread spectrum & CDMA tutorials, theory, and circuit diagrams, to development tools, OEM products, and consultants.

RF Resources -

A comprehensive collection of RF & microwave resources for wireless communication engineers. Includes tutorials, theory, design aids, circuit diagrams, products, and more.