RT7266

2

DS7266-02

September 2012

www.richtek.com

©

Copyright

2012 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

Pin No.

Pin Name

Pin Function

1

EN

Enable Input. A logic-high enables the converter; a logic-low forces the RT7266

into shutdown mode reducing the supply current to less than 10

μA. Attach this

pin to VIN with a 100k

Ω pull up resistor for automatic start-up.

2

FB

Feedback Input. It is used to regulate the output of the converter to a set value

via an external resistive voltage divider. The feedback reference voltage is

0.765V typically.

3

PVCC

Internal Regulator Output. Connect a 1

μF capacitor to GND to stabilize

output voltage.

4

SS

Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor

from SS to GND to set the soft-start period. A 3.9nF capacitor sets the soft-start

period to 1.5ms.

5, 9 (Exposed pad) GND

Ground. The Exposed pad should be soldered to a large PCB and connected to

GND for maximum thermal dissipation.

6

SW

Switch Node. Connect this pin to an external L-C filter.

7

BOOT

Bootstrap for High Side Gate Driver. Connect a 0.1

μF or greater ceramic

capacitor from BOOT to SW pins.

8

VIN

Supply Input. The input voltage range is from 4.5V to 18V. Must bypass with a

suitable large (

≥10μF x 2) ceramic capacitor.

Functional Pin Description

Table 1. Suggested Component Values

R1 (k

Ω)

R2 (k

Ω)

C3 (pF)

L1 (

μH)

C7 (

μF)

1

6.81

22.1

--

1.4

22 to 68

1.05

8.25

22.1

--

1.4

22 to 68

1.2

12.7

22.1

--

1.4

22 to 68

1.8

30.1

22.1

5 to 22

2

22 to 68

2.5

49.9

22.1

5 to 22

2

22 to 68

3.3

73.2

22.1

5 to 22

2

22 to 68

5

124

22.1

5 to 22

3.3

22 to 68

7

180

22.1

5 to 22

3.3

22 to 68

Typical Application Circuit

EN

RT7266

PVCC

FB

GND

VIN

10µF x 2

C1

0.1µF

C2

BOOT

L1

1.4µH

0.1µF

C6

22µF x 2

C7

SW

Chip Enable

SS

3.9nF

C5

1µF

C4

1.05V/3A

8

1

3

4

2

7

6

5, 9 (Exposed Pad)

8.25k

R1

22.1k

R2

C3