Rectifying 14.8v LiFEPO4 battery -- options

[jfsoar]

Hi,

I am designing a fairly complex circuit (a hat for a raspberry Pi flight computer) that is doing HDMI -> LVDS conversion, and bringing together various I2C and SPI sources.

Input is from a "12v" glider battery (which could, but not necessarily, be a LiFePO4 battery with 14.8V max nominal voltage) .

The LCD screen I am using has nominal 12v for the LED backlight, with 14v absolute max rating and a power consumption of 520mA at 100% duty cycle. ( datasheet https://texim-europe.com/getfile.ashx?id=109003)

Board space and power budget are at a premium and I already have circuits for 5V and 3.3V voltages. (LMZ12003 and TS2940).

I'm not especially bothered about maintaining 12V, but would like to avoid exceeding the absolute max rating. Screen brightness is important -- it will be run at near 100% duty cycle in extremely harsh sunlight.

I suppose there are a few options:
1. Stick in a diode with a 1V forward voltage drop. However that would waste half a watt of power which is too much.
2. Find some sort of power management IC that can output both 12V and 5V. Any recommendations?
3. Not worry about it and keep a lower duty cycle. Not sure I'm happy with this.

Any other ideas or pointers for option 2?

Thanks in advance

 

[barry]

You don't say if this a one-off project or a production design. There are a number of dual-output switchers, but there don't seem to be any that can accommodate 14.8 v input. So, your next best option is to add another switching regulator (assuming cost is not an issue).