LT1304-3.3 Linear Technology, LT1304-3.3 Datasheet - Page 10

• Manufacturer Part Number: LT1304-3.3
• Description: Micropower DC/DC Converters with Low-Battery Detector Active in Shutdown
• Manufacturer: Linear Technology

OPERATIO
LT1304/LT1304-3.3/LT1304-5
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.
TYPICAL APPLICATIONS
10
**
*
1% METAL FILM
SUMIDA CD54-330
2 CELLS
I
Q
+
10 A
2N3906
100 F
Super Burst
U
200k
47k
TM
Low I
LBO
FB
SHDN
V
IN
Q
47k
U
LT1304
DC/DC Converter
33 H**
GND
SW
I
LIM
LBI
22k
MBR0530
1.21M*
0.01 F
3.83M*
+
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
Super Burst is a trademark of Linear Technology Corporation.
220 F
5V
100mA
1304 TA03
100
90
80
70
60
50
40
30
20
10
0
1
90
80
70
60
50
40
0.01
LOAD CURRENT (mA)
10
Super Burst Efficiency
0.1
LOAD CURRENT (mA)
V
V
IN
IN
= 3V
= 2V
1.0
100
1304 F12
200
10
1304 TA04
100