Push pull driver for low power isolated rails
To generate low-power isolated voltage rails, Texas Instruments has released a push-pull driver for small transformers.
Called SN6501, it comes in a 5pin SOT23 and will run from rails between 3 and 5.5V.
Its output mosfets have an on-resistance of an Ohm or so and will sink 350mA from a 5V rail and 150mA from 3.3V. They are protected against the 11V swing possible at the free end of the transformer primary.
Operating frequency is around 400kHz, and output voltage depends on the transformer ratio and the rectifier type on the secondary side – which can include centre-tapped, voltage doubling and voltage quadrupling types.
TI expects applications in interfaces for RS-485, RS-422, RS-232, SPI, I2C and low-power LAN.
Wurth is making a range of 2.5kV isolation transformers for the chip, which are being stocked by Mouser in ratios between 1:1.1 and 1:2, and also stocks the TI part.
All the Wurth transformers are 6.7x 7.1x4mm.