Automotive voltage regulator

Several people make boost-buck switchers that could keep your 12 volt output pretty much constant. Sepics and flying-inductor things.

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John Larkin         Highland Technology, Inc 

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http://www.highlandtechnology.com 

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"Cold crank" (think upper peninsula of Michigan :-) specification is

4V which is where I designed my ignition systems to still function. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

voltage is clamped with TVS to

utdown during cranking.

for any regulator with a drop put voltage of 1-2V.

M2268X) and then another 12V to 5V buck regulator. What will be the output of adjustable buck switching regulator if the input voltage goes below the required output voltage? Will the o/p drop to zero or Vin - dropout?

converter like LMR64010.

tion.

The unit has a board/module inside which has operating range of 8V-12V and

5V is to the micro and peripherals. So operation down to 4V isn't really re quired.

If systems don't have to be functional during engine crank, a simple way is to simply hold those circuits in reset until the engine is running. For analog circuits simply think power management. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

There are several bucks that allow high duty-cycle operation. I have the same problem and have been using a TI TPS65320 for 5V. It's pretty cheap, works to 2MHz, and includes a free LDO (which switches from the input to the output when the buck turns on). As John points out, there are several boost/bucks around now. Some will operate the boost in pass-thru mode (boost shuts down) when the input voltage allows it. Look in the catalogs under the automotive parts. This is a very common need.

Have a look at system basis chips if you have a CAN/LIN requirement as well.

Most are linear, there are some buck/boost versions but I don't know any off the top of my head.

wrote in message news: snipped-for-privacy@googlegroups.com... I have a need for 12V 250ma and 5V 1.2A outputs from car battery. Input voltage is clamped with TVS to