STEVAL-ILL008V1 STMicroelectronics, STEVAL-ILL008V1 Datasheet - Page 6

• Manufacturer Part Number: STEVAL-ILL008V1
• Description: EVAL BOARD CREE LED FLASHLIGHT
• Manufacturer: STMicroelectronics

Specifications of STEVAL-ILL008V1

• Mfg Application Notes: Low Voltage LED Driver AppNote
• Design Resources: STEVAL-ILL008V1 Gerber Files STEVAL-ILL008V1 Schematic STEVAL-ILL008V1 Bill of Materials
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 3.5V
• Features: 1V Start up Input Voltage
• Voltage - Input: 1 ~ 5.5 V
• Utilized Ic / Part: L6920
• Product: Display Modules
• Core Chip: L6920DA
• Output Voltage: 3.5V
• Kit Contents: L6920D, L4971, L6902D Reference Board
• Development Tool Type: Hardware - Eval/Demo Board
• Tool / Board Applications: LED Flashlight
• Mcu Supported Families: L6920DA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output / Channel: -
• Lead Free Status / Rohs Status: Details
• Other names: 497-5516

L6920
Figure 7. PFM mode Condition: V
Trace1: Vout (50mV~/div) Trace 4: IL (100mA/div)
Time div.: 5µs/div
Figure 8. Heavier load - Train pulses overlapping.
Trace1: V
Time div.: 10 µs/div
When Iload is heavier, the pulse trains are overlapped. Figures 7 - 8 show some possible behaviors.
Considering that current in the inductor is limited to 1A, the maximum load current is defined by the following
relationship:
Where η is the efficiency and I
Of course, if Iload is greater than Iload_lim the regulation is lost (figure 11).
6/13
out
(100mV~/div) Trace 4: I
I
load_lim
lim
=1A.
out
=
L
= 5V; V
(200mA/div)
---------- -
V
V
out
in
in
⋅
⎛
⎝
=1.5V.
I
lim
–
T
off min
Figure 9. Heavy load - Inductor current ripples
below I
(200mA/div) Time div.: 20 µs/div
Figure 10. Heavy load and High ESR. Regulation
falls in continuous mode of operation. Trace1:
V
div.: 5 µs/div
out
⋅
V
------------------------- -
(100mV~/div) Trace 4: I
out
2 L
lim
⋅
–
Trace1: V
V
in
⎞ η
⎠
⋅
eq. (1)
out
(100mV~/div) Trace 4: I
L
(200mA/div). Time
L