SP6685ER 데이터 시트보기 (PDF) - Signal Processing Technologies

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SP6685ER

700mA Buck/Boost Charge Pump LED Driver

Signal Processing Technologies 

TYPICAL PERFORMANCE CHARACTERISTICS

Application Circuit = Figure 31, TA = 25°C.

100

90

80

Flash 600mA

Flash 300mA

Torch 150mA

Flash 400mA

Flash 500mA

Efficiency

70

60

50

40

3.0

3.2

3.4

3.6

3.8

4.0

4.2

Vin (V)

Output Current

900

Flash 600mA Vf=4.34V

800

Flash 500mA Vf=4.13V

Flash 400mA Vf=3.93V

700

Flash 300mA Vf=3.72V

Torch 150mA Vf=3.33V

600

500

400

300

200

100

0

3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2

Vin (V)

Figure 29. Efficiency vs. VIN.

Figure 30. Output Current vs. VIN.

APPLICATION INFORMATION

The SP6685 can be used with multiple LEDs in parallel as shown in figure 31. For best

performance, the LEDs should be in a single package, preferably from a single die to have

better matching for forward voltage Vf for a given forward current If. In practice, if the Vf of one

LED is higher than the others, it will consume a larger If, which will raise its temperature which

will then cause its Vf to reduce, correcting the imbalance. The overall current will be the sum

of the individual currents, for example Itotal = 4*ILED.

Vin: 3.0-4.2V

1

Cin

10uF

CF

1uF

2

3

J2

SP6685

1 Vin

VOUT 10

2 C1

PGND 9

3 C2

SGND 8

4 FLASH

IFB 7

5 EN

ISET 6

Jumper

SW2

R EN

10K

R SET

139K

Push ON

Cout

4.7 uF

D1

Sharp LED

GM5BW05340AC

R FB VFB = 50mV Torch150mA

0.33 Ohm

100mV Flash 300mA

Figure 31. MULTIPLE LED FLASH CIRCUIT.

Date: 7/6/06 Rev B

SP6685, 700mA Buck/BoostCharge Pump LED Driver

10

© 2006 Sipex Corporation

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