LT1304/LT1304-3.3/LT1304-5
U
OPERATIO
100
90
80
70
60
50
40
30
20
10
0
Figure 12 shows overall energy conversion efficiency,
assuming availability of 6.5WH of battery energy. This
efficiency approximates the electrical efficiency at load
current levels from 1mA to 10mA, but drops severely at
loadcurrentsabove10mA(loadpowerabove50mW).The
moral of the story is this: if your system needs 5V at more
than 40mA to 50mA, consider using a NiCd battery (1/10
the internal impedance) instead of a AA cell alkaline
battery.
1
10
100 200
LOAD CURRENT (mA)
1304 F12
Figure 12. Overall System Efficiency Including Battery Efficiency
vs Load Current. Internal Impedance of Alkaline AA Cells
Accounts for Rapid Drop in Efficiency at Higher Load Current
U
TYPICAL APPLICATIONS
Super BurstTM Low IQ DC/DC Converter
Super Burst Efficiency
MBR0530
I
Q
≈ 10µA
33µH**
90
200k
47k
0.01µF
V
= 3V
= 2V
IN
IN
2N3906
80
70
60
50
40
V
SW
IN
3.83M*
5V
LBO
LBI
100mA
+
V
2 CELLS
100µF
LT1304
FB
I
+
LIM
1.21M*
220µF
SHDN
GND
47k
22k
0.01
0.1
1.0
10
100
*1% METAL FILM
**SUMIDA CD54-330
1304 TA03
LOAD CURRENT (mA)
1304 TA04
Super Burst is a trademark of Linear Technology Corporation.
10
Linear [ Linear ]
