EL7513
Block Diagram
2.6V TO
5.5V
CIN
4.7µF
VIN
REFERENCE
GENERATOR
1MHz
OSCILLATOR
THERMAL
SHUTDOWN
OVER-VOLTAGE
PROTECTION
COMP
CCOMP
0.1µF
PWM
SIGNAL
VCNTL CNTL
617k
50k
+++
BOOST
I-SENSE
START-UP
CONTROL
ERROR AMP
+
-
PWM
LOGIC
L
33µH
VOUT
LX
I(LED)
PGND
CS
5
SGND
COUT
1µF
Typical Performance Curves
All performance curves and waveforms are taken with C1 = 4.7µF, C2 = 1µF, C3 = 0.1µF, L = 33µF, VIN = 3.3V, VCNTL = 1V, R1 = 5, 4 LEDs in a
series; unless otherwise specified.
1.05
1.04
1.03
1.02
1.01
1.00
2.5 3.0 3.5 4.0 4.5 5.0 5.5
VIN (V)
FIGURE 1. SWITCHING FREQUENCY vs VIN
3.5
VCNTL = 0V, 0.1V
3.0 WHITE LEDs DISCONNECTED
2.5
2.0
1.5
1.0
0.5
0
2.5 4.5 6.5 8.5 10.5 12.5 14.5
VIN (V)
FIGURE 2. QUIESCENT CURRENT
FN7112 Rev 5.00
December 22, 2008
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