MP3378E

– 4-CHANNEL WLED CONTROLLER WITH BUCK CONVERTER

MP3378E Rev. 1.02

www.MonolithicPower.com

21

5/26/2017

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PCB Layout Guidelines

Efficient PCB layout is critical for achieving stable

operation. If the layout is not done carefully, the

regulator can show poor line or load regulation.

For best results, refer to Figure 7 and Figure 8

and follow the guidelines below:

For the WLED converter (see Figure 7):

1. Keep the loop from the external MOSFET

(M1), the output diode (D1), and the

output capacitors (C2, C3) as small and

short as possible to reduce EMI noise.

2. Separate the power ground and signal

ground.

3. Connect PGND and GND.

NOTE: All logic signals refer to the signal ground.

For the buck converter (see Figure 8):

1. Keep the connection of input ground and

GND2 (PGND) as short and wide as

possible.

2. Keep

the

connection

of

the

input

capacitors (C16, C16A, C17) and VIN2 as

short and wide as possible.

3. Ensure that all feedback connections are

short and direct.

4. Place

the

feedback

resistors

and

compensation components as close to

the chip as possible.

5. Route SW away from sensitive analog

areas, such as FB.

6. Connect

a resistor (R23) to AGND, as

SYNC is sensitive to noise. Otherwise,

the SCP may fail, and the buck converter

may be damaged.

7. Connect GND1 and GND2 together by a

single point.

28

27

26

25

24

23

22

21

20

19

18

17

16

15

VIN2

SW

GND2

GND2

AGND

BST

SYNC

ISENSE

GATE

VIN1

VCC1

COMP

EN1

PWM

VLED

VIN1

GND1

L1

D1

C2

C3

R6

M1

Figure 7: Recommended Boost Driver Layout

SYNC

7

8

LED2

LED1

9

10

11

12

13

14

OVP

NC

NC

FB

EN2

VCC2

22

21

20

19

18

17

16

15

VIN2

SW

GND2

GND2

BST

ISENSE

C16

C17

GND2

VIN2

SW

C16A

R23

C21

C21B

C21A

R31

R27

R26

C18

VOUT

GND2

AGND

Figure 8: Recommended Buck Converter Layout