Need Advice on DC-DC step up system

[Gandalf_Sr]

My requirement is to step up from 5 to 9 V to ± 100 to 150 V with a PIC controlling the voltages. I can do the PIC bit but I'm unsure on which SMPS topologies would be best.

The ±100 to 150 V supplies will be required to deliver up to 300 mA pulses into a load that will be in the range of 500 - 1000 ohms so instantaneous power is 90W but the duty factor (on / off times) is 0.015 (it's on for a max of 300 uS in any 20 mS) so the average power (not counting losses) is under 2 W.

The output also needs to be current controlled / limited if that affects the SMPS design?

I've considered the following:
- SEPIC
- Flyback
- Boost

Efficiency is a big factor because this is going to run off batteries.

Thanks in advance for any helpful suggestions

 

[karesz]

Hi,
You can study the LT3957, possible is a good component for both polarities, I think hes efficiency is not so bad slightly over 90%(+/-)...
http://cds.linear.com/docs/Datasheet/3957f.pdf
K.

 

[Gandalf_Sr]

Thanks for the quick response Karesz, that chip looks useful but it's just one of many SMPS switcher control ICs out there.

What I'm still struggling with is which topology offers the best solution in terms of generating the high voltage I need with reasonable efficiency.

 

[karesz]

How is +/-100V pulse to understand pls, is it symmetrically referenced to GND?..
I think for that job is an PI switcher good & isnt expensive. You will find lot of apps & design references on hes homside...
You can download/study PIExpert7.x _is good documented designer SW.
Otherwise has ST & TI other nice (some are similar as from PI) circuits too
K.

 

[Gandalf_Sr]

± 150 V pulses are referenced to ground, actually they are ±xxx mA pulses where xxx ranges from 10 to 300 mA. The output needs to be controlled constant current because the load can vary up to 1000 ohms.

First there will be a (up to) 300 uS + pulse and then a small (200uS) gap and then a (up to) 300 uS - pulse, and then a long (10mS to 20mS) gap before it all repeats again. Pulses are current controlled. this requirement is what the power supply is for.

If I can generate the +ve voltage, is there an easy way to generate the -ve voltage or do I need a second SMPS?

PI Switcher looks interesting, I will check it out.

 

[karesz]

I become yet these in news_seems to be interesting too:
Single-chip combines power optimization, conversion for solar
**broken link removed**
K.

 

[karesz]

Hi Gandalf,
Maybe is it an idea for you? :
Half Bridge Driver Generates 100V, 10A, 4μs Pulses
www.intersil.com/data/an/an1377.pdf
K.