10

LT1304/LT1304-3.3/LT1304-5

OPERATIO

LOAD CURRENT (mA)

1

100

90

80

70

60

50

40

30

20

10

0

10

100

1304 F12

200

SW

SHDN

GND

LBI

LBO

FB

LT1304

+

+

220

µF

100

µF

0.01

µF

47k

2 CELLS

33

µH**

5V

100mA

1% METAL FILM

SUMIDA CD54-330

*

**

1304 TA03

47k

22k

1.21M*

3.83M*

MBR0530

200k

2N3906

Super Burst

LOAD CURRENT (mA)

40

50

70

60

80

90

100

1304 TA04

0.01

0.1

1.0

10

Super Burst Efficiency

Super Burst is a trademark of Linear Technology Corporation.

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

load currents above 10mA (load power above 50mW). 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.

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