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© 2005 Semtech Corp.

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POWER MANAGEMENT

SC4501

Typical Application Circuits

C1

2.2

µF

SC4501

2

3

1

5

6

4

GND

SHDN

SS

IN

SW

FB

ROSC

COMP

8

7

R4

10BQ015

D1

C3

10nF

4.7

µF

C2

R2

43.2K

R1

698

8.06K

C4

10nF

L1

2.2

µH

R5

10K

0.1

Ω

R6

2.6 - 4.2V

1-CELL

LI-ION

1/2

LM358

0.2A (TORCH)

MMBT 3904T

SUMIDA

CR43

ON

OFF

D2

LXCL-PWF1

Q1

C5

0.1

µF

R6

17.4K

FLASH

TORCH

- 3.4V to 3.8V +

MMBF2201NT1

M1

0.7A (FLASH)

Figure 14(b) and 14(c). Photo Flash LED Current is Switched Between Torch Mode (0.2A) and Flash Mode (0.7A).

CH1 : Torch/Flash Control Voltage, 5V/div

CH4 : Inductor Current, 1A/div

CH2 : FB Pin Voltage, 1V/div

CH3 : LED Current, 0.5A/div

Higher LED Current (>0.7A) in Flash Mode is Possible with Fresh Battery.

4ms/div

CH1

CH2

CH3

CH4

(b)

CH1

CH2

CH3

CH4

4ms/div

(c)