Rainbow Electronics MAX1554 - Manual (Page 5)

MAX1553/MAX1554
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(MAX1553 driving six white LEDs, V CC = V EN = 3.6V, Circuit of Figure 1, T A = +25°C, unless otherwise noted.)
SWITCHING WAVEFORMS
(CONTINUOUS OPERATION,
3.75V Li+ BATTERY, 18mA OUTPUT)
MAX1553/54 toc10
2 µs/div
V LX
V OUT
I
L
10V/div
200mV/div
200mA/div
L1 = 47 µH, 4700pF CAPACITOR ACROSS LEDs
SWITCHING WAVEFORMS
(DISCONTINUOUS OPERATION,
3.75V Li+ BATTERY, 10mA OUTPUT)
MAX1553/54 toc11
2 µs/div
V LX
V OUT
I
L
10V/div
200mV/div
200mA/div
L1 = 47 µH, 4700pF CAPACITOR ACROSS LEDs
STARTUP/SHUTDOWN WAVEFORMS
MAX1553/54 toc12
40ms/div
V EN
V FB
V OUT
5V/div
200mV/div
10V/div
L1 = 22 µH
BRT STEP RESPONSE
MAX1553/54 toc13
20ms/div
V BRT
V FB
V OUT
1V/div
200mV/div
2V/div
L1 = 22 µH,
V BRT = 0.5V TO 1.25V TO O.5V