STEVAL-ILL008V1 STMicroelectronics, STEVAL-ILL008V1 Datasheet - Page 4

• 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

AN1941 APPLICATION NOTE
Figure 4. Upper trace: inductor current; lower track: LED current
Figure 5. Upper trace: inductor current; lower track: LED current
from the waveforms, the inductor peak current is limited at 1A. the maximum load current is
defined by following relationship:
where
When the load is heavier than I
go to continuous mode. Fig. 6 and Fig. 7 show that the circuit loses the regulation, but the cir-
cuit is running at its maximum duty cycle.
Figure 6. Vin = 1V; upper trace: inductor current; lower trace: LED current
4/15
is the efficiency, I
I
load_lim
lim
=1A, and T
load_lim
=
------------ - I
Vout
Vin
, the regulation will be lost, and the inductor current will
offmin
lim
–


=1 s.
I
T
LED
I
L
off min
500mA/div
100mA/div
I
I
I
I
I
LED
LED
Vout Vin
---------------------------- -
LED
L
L
500mA/div
500mA/div
100mA/div
100mA/div
I
2 L
100mA/div
L
500mA/div
–

