DC Converter Needed
DC Converter Needed
(OP)
I need a DC-DC converter which is capable of taking a wide input range from + 6-24 Vdc and giving a constant output of +9 Vdc, 150mA.
I have looked at various suppliers components and they all seem to have Vin ranges from 4.5 - 9 Vdc or 9 - 18 Vdc, and they're not suitable for my application purpose!!
the converter has to be fit on to a PCB a SIP8 package is needed.
any ideas of any device/converter that I might be able to use???
cheers
I have looked at various suppliers components and they all seem to have Vin ranges from 4.5 - 9 Vdc or 9 - 18 Vdc, and they're not suitable for my application purpose!!
the converter has to be fit on to a PCB a SIP8 package is needed.
any ideas of any device/converter that I might be able to use???
cheers





RE: DC Converter Needed
RE: DC Converter Needed
Try the SEPIC converter. The x'fer function is:
Vout/Vin = D/(1-D), where D = duty cycle
The circuit needs 2 inductors, and, the control loop is harder to stabilize than a regular buck or boost.
Bhuvan
RE: DC Converter Needed
What about one of those DCDC converters which uses two BJT's in a kind of multivibrator set-up, with the primary coil being used with a resistor and a cap somewhere to oscillate and get the primary current backwards-and-forwards-ing through the primary.
I've seen these often with low power dcdc's and they have minimal component count...and don't care too much about the low-end of your vin.
.....come to think of it, i just took apart a £1.27 compact fluorescent bulb and it had one of these two-BJT oscillators acting as a high frequency ballast in the base of the bulb....
...also, a recent company that i just finished with used one to provide an isolated 15V rail voltage in their new electric drive.
...and another company that make electro microscopes still use them to this day.
RE: DC Converter Needed
Here you go:
ht
Keith Cress
kcress - http://www.flaminsystems.com
RE: DC Converter Needed
here is another one http://www.national.com/pf/LM/LM5118.html
RE: DC Converter Needed
Keith Cress
kcress - http://www.flaminsystems.com
RE: DC Converter Needed
The LM5118 is a buck-boost. It will work for your application. (that is, the LM5118 and 20 extra components)
DH
RE: DC Converter Needed
Yeah, guys - don't forget all the extra components (and prototyping/debugging time) it takes when you want to roll your own here... Those little 1-2W encapsulated converters from V-Infinity, C&D, etc., sure are hard to beat when you consider price, pcb real estate and development time!
RE: DC Converter Needed
Get out the parts bin.
Keith Cress
kcress - http://www.flaminsystems.com
RE: DC Converter Needed
For PWM control, you need a flip-flop and two open collector comparators and a two input AND gate. If these three are not available on a single chip then that means using separate chips. Wire it up as a flyback
you can wire these up with one comparator switching on output overvoltage, the other on overcurrent, the flip-flop to avoid multiple turn on/off. and the AND gate to control the switch (AND gate fed from flip and also oscillator)......possibly use just a BJT at this low power...being driven on by the non CMOS AND gate...eg use 74 series
but at such low power the linear regulator looks good.
RE: DC Converter Needed
Find the SO version of the 494; it is roughly the same size
as a SIP8 device. Adjust the 5.1k to pin 1 as necessary.
<als>
RE: DC Converter Needed
RE: DC Converter Needed
DC
Dean Cooper
dclabseng.com