Datasheet

10 70
85
93
95
40
88
90
Efficiency - %
98-W EFFICIENCY WITH PWM DIMMING
86
89
91
94
100
Dimming - %
Efficiency 390 V
Efficiency 370 V
Efficiency 410 V
87
92
25 55 85
100 10000
Frequency
-60
30
60
1000
-30
0
Gain - dB
-180
135
180
-135
0
Phase - Degrees
CURRENT LOOP FREQUENCY LOOP
-90
-45
45
90
-45
-15
15
45
100000
Mag [B/A]
Phase [B-A]
www.ti.com Test Data
9.2 Efficiency
Measuring efficiency with PWM dimming requires the use of power analyzers on the LED output/s. The
following efficiency table was taken with LED voltage strings set to roughly 98 V.
Figure 8. Efficiency 10% to 100% PWM Dimming
9.3 Control Loop Frequency Response
Current loop crossed over at roughly 5 kHz with greater than 45 degrees of phase margin. Each LED
output was loaded with 32 Cree XLamp XR-E diodes. At full load the current was controlled to a target
current of 250 mA through each LED output string.
Figure 9. Loop Gain, V
IN
= 390 V, Outputs Loaded with 32 LEDs (98 V) and No PWM Dimming
11
SLUU487A–March 2011–Revised March 2011 98-W Resonant LLC, 4-String LED Driver
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