LM3409 Datasheet, PDF (23/30 Pages) National Semiconductor (TI) – PFET Buck Controller for High Power LED Drives

8. INPUT UVLO
Solve for R_UV2:
The closest 1% tolerance resistor is 6.98 kΩ therefore V_TURN-
ON ^is:
The closest 1% tolerance resistor is 49.9 kΩ therefore V_HYS
is:
Solve for R_UV1:
The chosen components from step 8 are:
Design #2 Bill of Materials
Qty
Part ID
1
LM3409
2
C_IN1
1
C_F
1
C_F2
1
C_OFF
1
C_O
1
Q1
1
D1
1
L1
1
R_F2
1
R_OFF
1
R_UV1
1
R_UV2
1
R_SNS
9. IADJ CONNECTION METHOD
The IADJ pin is connected to an external voltage source and
varied from 0 – 1.24V to dim. An RC filter (R_F2 = 1 kΩ and
C_F2 = 0.1µF) is used as recommended.
10. PWM DIMMING METHOD
No PWM dimming is necessary.
Part Value
Buck controller
4.7µF X7R 10% 50V
Manufacturer
NSC
MURATA
1.0µF X7R 10% 16V
0.1µF X7R 10% 16V
470pF X7R 10% 50V
2.2µF X7R 10% 50V
TDK
TDK
TDK
MURATA
PMOS 70V 5.7A
Schottky 60V 5A
22 µH 20% 4.2A
1.0kΩ 1%
15.4kΩ 1%
6.98kΩ 1%
49.9kΩ 1%
0.2Ω 1% 1W
ZETEX
COMCHIP
TDK
VISHAY
VISHAY
VISHAY
VISHAY
VISHAY
Part Number
LM3409MY
GRM55ER71H475MA0
1L
C1608X7R1C105K
C1608X7R1C104K
C1608X7R1H471K
GRM43ER71H225MA0
1L
ZXMP7A17KTC
CDBC560-G
SLF12575T-220M4R0
CRCW06031K00FKEA
CRCW060315K4FKEA
CRCW06036K98FKEA
CRCW060349K9FKEA
WSL2512R2000FEA
23
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