SC4501 Semtech Corporation, SC4501 Datasheet - Page 19

• Manufacturer Part Number: SC4501
• Description: 2MHz Step-Up Switching Regulator
• Manufacturer: Semtech Corporation

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POWER MANAGEMENT
Typical Application Circuits
2005 Semtech Corp.
Figure 14(b) and 14(c). Photo Flash LED Current is Switched Between Torch Mode (0.2A) and Flash Mode (0.7A).
CH1
CH2
CH3
CH4
2.6 - 4.2V
1-CELL
LI-ION
Figure 14(a). 1.4MHz Luxeon
4ms/div
2.2 F
C1
(b)
Higher LED Current (>0.7A) in Flash Mode is Possible with Fresh Battery.
OFF
V
ON
IN
= 2.6V
10nF
3
8
C3
CH2 : FB Pin Voltage, 1V/div
CH1 : Torch/Flash Control Voltage, 5V/div
CH3 : LED Current, 0.5A/div
CH4 : Inductor Current, 1A/div
SHDN
SS
IN
GND
6
4
SUMIDA
SC4501
2.2 H
CR43
0.7A (FLASH)
0.2A (TORCH)
L1
ROSC
7
COMP
TM
5
SW
R4
8.06K
FB
Flash White LED Driver for Camera Phones
2
1
19
C4
10nF
TORCH
0.1
R6
R5
10K
C5
0.1 F
LM358
R1
698
1/2
FLASH
- 3.4V to 3.8V +
LXCL-PWF1
CH1
CH2
CH3
CH4
D2
M1
MMBF2201NT1
R6
17.4K
Q1
MMBT3904T
R2
43.2K
10BQ015
4ms/div
D1
(c)
C2
4.7 F
V
IN
= 4.2V
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SC4501