lra.changelog

TODO
remove charging USB plug and charge from uno. Uno's vin pin is powered when we put voltage into 5v so we have nothing to detect Uno voltage
swap TPS61200 for 7.5V booster and feed vin instead of 5v pin. We lose voltage through Uno's linear regulator but allow Uno to safely switch UNO USB off if our voltage present

V.02
add switch battery on/off
silk size increased for readability
move leds to 0805
drv works just fine at 5v - remove all dividers and 2.8v regulator
added pin 1 indicator for drv2603
swapped motor OUT + - pins
move usb and lipo connector
created long variants for hand soldering of both qfn parts
cleaned up tps61200 routing and layout
remove resistors on vin, en and PS on tps61200
solder selector on PS
removed PWR led
upgraded to UNO R3 shield pinout
recalc UVLO for 3.2 re http://vvishnyakov.blogspot.co.uk/2013/02/documenting-hardware-bug-in-sparkfun.html

V.01 (changes from Lipo 8/1/11)
new layout
move usb and lipo connector
move to 0805s
remove fuel cell
remove 3v regulator, add 2.8v regulator
remove proto area
add drv circuits


UVLO
r3 =r4 x (vinmin) -1
		   uvlo 


uvlo = .250
r4 ~ 250K
vinmin = 3.2



r4=250k
r3 =2.95M


OR 
		   
1  =1/r3 * (vinmin) -1
r4			uvlo


1/x = 1/2000000 * 3.2/.250 - 1

1/x = 1/2000000 * 11.8


r3 = 2M
r4 = 169.5K

or 

r3=3M
r4=254K