RT9278

Preliminary

2

DS9278-04 August 2007

www.richtek.com

Typical Application Circuit

Figure 1. Novel Up-Down Driver for Power LED with Strobe Mode

Figure 3. Synchronous Boost Converter with Load Disconnect in Shutdown

Note :

l

Patent Pending.

l

The GPIO Signal has to pull high before enable IC.

Figure 2. Novel Up-Down Driver for Power LED with Strobe Mode and Movie Mode

Note : Patent Pending.

4

3

1

2

8

7

9

5

V

IN

LX

EN

LFB

LDRI

PGND

FB

VOUT

VDD

C1

C4

C3

C2

R1

RT9278

10uF

1uF

GND

COMP

R2

2.2nF

10uF

L1

510k

2.5k

4.7uH

3.3V

10

C5

100pF

R3

470k

R4

150k

Q1

AO3403

6

Chip Shutdown

Chip Enable

V

OUT

4

3

1

2

10

7

9

5

V

IN

LX

EN

LFB

LDRI

PGND

FB

VOUT

VDD

C1

C3

C2

R1

RT9278

4.7uF

1uF

GND

COMP

C4

12nF

L1

2.2uF

2.2k

1 to 10uH

8

R2

300k

D1

Power LED

R3

0.28

Q1

AO7401

Chip

Shutdown

Chip Enable

6

100ms

700mA

100ms

R3)

x

(I

0.2

R4

x

0.2)

(GPIO_HI

R5

I

0.2

R3

1k

Ω

R4

Movie

Strobe

−

−

=

=

=

4

3

1

2

10

7

9

5

V

IN

LX

EN

LFB

LDRI

PGND

FB

VOUT

VDD

C1

C3

C2

R1

RT9278

4.7uF

1uF

GND

COMP

C4

12nF

L1

2.2uF

2.2k

8

R2

300k

D1

Power LED

R3

0.28

Q1

AO3403

Chip Shutdown

Chip Enable

6

R4 1k

R5

18.2k

GPIO

0V

2.8V

GPIO

100ms

700mA

200mA

I

Movie

I

strobe

1 to 10uH