STEVAL-ILL008V1 STMicroelectronics, STEVAL-ILL008V1 Datasheet - Page 12

• 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 16. Schematic
4.2 Circuit description:
The IC can operate up to 36 volts. The 25 volt input capacitor was the restricting factor for the
input and output voltage. More LEDs can be driven if a 35 volt cap is used for C1 and C2. C3,
C4, and R3 stabilize the feedback loop. R1 and R2 set the output voltage limit to 23.2 volts,
below the rating of the output capacitor. D1 recirculates the current when the internal 250m
P-channel DMOS transistor is turned off. R4, 0.3 ohms 1% standard resistor, sets the current
to 330mA. R4a, 6.2 ohms tweaks it to 350mA for the precise industry standard. L1 is deter-
mined as shown in the Table 4.
Table 5. BOM:
12/15
Qty
1
1
1
1
1
1
1
1
1
1
1
1
Vin=8 to 25V
GND in
1
1
C1
10uF
25V
R4a
Ref
C1
C2
C3
C4
D1
R1
R2
R3
R4
U1
L1
C3
220pF
C4
22nF
R3
5.1K
STPS340U
8
6
4
L6902D
150uH
220pF
10uF
47uF
22nF
Vcc
Vref
Comp
Part
4.7K
5.1K
240
.30
6.2
U1
L6902D
0
CS+
CS-
Out
FB
1
2
3
5
Voltage
350ma
D1
STPS340U
25V
25V
1W
1W
ST
ST
L1
150uH
PCC2243CT
P10267
PCC221BVCT
PCC2283CT
STPS340U
MOS-6020-154MXB
P3.9KGCT
P240GCT
P5.1KGCT
71-WSL2010-0.332
71-WSL2010-0.332
L6902D
R4a
6.2
1W
R4
.30
1W
I=350 mA up to 23.2V
R1
4.7K
R2
240
Cat #
+
C2
47uF
25V
1
1
Vout
GND out