Low power PWM controller, possibly the 555 (flame war coming)

Klaus Kragelund · 2012-08-30T11:05:39+00:00

HiI am working on a small 100mW forward converter and I need a very low power PWMcontrol.So the 555 comes up, along with some ultra low power opamps. But, isn't there aPWM chips out there with low operating current. Sofar I found the TPS5110 withsub mA current consumption:Anyone used one with lower current?ThanksKlaus

Aug 30, 2012 61 Replies

Rate this thread:

John Larkin 13 years ago

the most I think....

and leave the other with you wife or whoever wants to go down that road?

We of a certain age used to be good at everything electronic, because there wasn't all that much. Nowadays, what with PCI Express and USB and VHDL and 1400 page ARM data sheets and an explosion of analog/digital/fiberoptic/DSP/Ethernet technology, nobody can do it all.

I knew guys who gave up electronics because they couldn't handle the transition from tubes to transistors. Sometimes I feel that way over Linux DMA drivers and 10,000 line Verilog modules and PCIe.

Geez, what should be a simple parallel ADC now has six pages in the data sheet documenting the sideband SPI control registers.

Every once in a while I have to design something simple, that I can do all by myself, with no FPGA or uP, like a little wideband amp or a laser driver. Sometimes people even buy them.

This is cute, 4 square inches of analog simplicity:

formatting link

John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

Vote

legg 13 years ago

control.

PWM chips out there with low operating current. Sofar I found the TPS5110 with sub mA current consumption:

UCC3805 is a simpler part, possibly with lower part count and quiescent current. It could also has an output stage that could drive a transformer directly, at low power.

It has the same low voltage 3-5V operating range as TPS5110. Other versions are available for 8, 12 and 15V.

formatting link

Otherwise, a couple of nand gates and a bipolar transistor will be about the most basic, lowest power, hard-switching controller. Typified by the drawing on page three here:

formatting link

You'd modulate it by biasing the bipolar tansistor, directly through a simple zener or isolated with optocoupler. You might use a transformer in the feedback, but that's a hard sell at most power levels, nowadays.

These guys sure get off-topic, fast, don't they.

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required