UTCLT1304/LT1304-3.3V/LT1304-5.0V

LINEAR INTEGRATED CIRCUIT

10

QW-R103-018,A

Figure 7. Suggested Layout for Best Performance.Input Capacitor Placement as

Shown Is Highly Recommended.Switch Trace (pin 4) Copper Area Is Minimized

SHUTDOWN

+

LT1304

8

7

6

5

1

2

3

4

+

GND (BATTERY AND LOAD RETURN)

Low-Battery Detector

The LT1304 contains an independent low-battery detector that remains active when the device is shut down. This

detector, actually a hysteretic comparator, has an open collector output that can sink up to 500µA.The comparator

1.4V.Figure 8 illustrates the input /output characteristic of the detector. Hysteresis is clearly evident in the figure.

2V/DIV

Figure 8. Low-Battery Detector Transfer Function.

Pull-Up R=22K,VIN=2V,Sweep Frequency=10Hz

200mV/DIV

Battery Life

How may hours does it work? This is the bottom line question that must be asked of any efficiency study. AA

alkaline cells are not perfect power sources. For efficient power transfer, energy must be taken from AA cells at a

rate that does not induce excessive loss. AA cells internal impedance, about 0.2

Ω fresh and 0.5Ω end-of-life, results

in significant efficiency loss at high discharge rates. Figure 10 illustrates battery life vs load current of Figure 9’s

LT1304, 2-cell to 5V DC/DC converter. Note the accelerated decrease in hours at higher power levels. Figure 11

plots total watt hours vs load current. Watt hours are determined by the following formula: