Wednesday, September 06, 2017

Offline Isolated Flyback LED Controller - LT3799-1

This chip for LED driving has a power factor correction, the critical conduction mode keeps transformer small. A opto-coupler for feedback is avoided by an innovative primary shunt monitor.

Offline Isolated Flyback LED Controller - LT3799-1

The LT3799-1 uses a micropower hysteretic start-up to efficiently operate at offline input voltages, with a third winding to provide power to the part. An internal LDO provides a well regulated supply for the part’s internal circuitry and gate driver.

LED Controller - LT3799-1

20 Watt LED Driver using LT799-1

The FAULT pin provides notification of open and short LED conditions. The LT3799-1 offers improved line regulation over the LT3799, but is not designed for use with a TRIAC dimmer.

Features
  • Offline 4W to 100W+ LED Applications
  • High DC VIN LED Applications
  • Gate driver to drive an external high voltage MOSFET.
  • Typical power factors of 0.97.

Tuesday, September 05, 2017

LED Drive using TPS61042

This Chip from TI is simple to integrate into your designs and this solution is good for production of lighting gadgets, here a consistent quality and predictable performance is easily obtained.

TPS61042 30-V, 500-mA Switch Boost Converter  for White LED Applications
LED-driver application that drives four LEDs with 20 mA of forward current and operates from an input voltage range of 1.8 to 6.0 V.

The entire circuit consists of the control IC, two small ceramic caps, an inductor, a diode, and a current sense resistor. The primary power-supply functions and the secondary features such as load disconnect, overvoltage protection, and PWM dimming have been implemented with a control IC and five small surface-mount passive components.

LED Drive using TPS61042

LED-driver considerations - By Michael Day

Many of today’s portable electronics require backlight LED-driver solutions with the following features: direct control of current, high efficiency, PWM dimming, overvoltage protection, load disconnect, small size, and ease of use.

Monday, September 04, 2017

AD636 - True RMS to DC Converter

Working on low signals in the range of 0 mV to 200 mV rms, AD636 makes a precision AC to DC signal conditioner for Instrumentation. DMM, Data Loggers and Process Indicators can use this.

AD636 - True RMS to DC Converter

Using this chip you can make a True RMS Voltmeter for your Lab or Project.


The AD636 is easy to use. The device is factory-trimmed at the wafer level for input and output offset, positive and negative waveform symmetry (dc reversal error), and full-scale accuracy at 200 mV rms. Therefore, no external trims are required to achieve full-rated accuracy.

Some Features and Specs
  • Laser-trimmed to high accuracy
  • 0.5% maximum error (AD636K)
  • Computes rms of ac and dc signals
  • 1 MHz, −3 dB bandwidth: V rms > 100 mV
  • Signal crest factor of 6 for 0.5% error
  • Low power: 800 μA quiescent current