SC624 Ver la hoja de datos (PDF) - Semtech Corporation

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Fabricante

SC624

LED Light Management Unit Charge Pump, 4 LEDs, Dual LDOs, and SemWire™ Interface

Semtech Corporation 

SC624

Applications Information (continued)

PCB Layout Considerations

The layout diagram in Figure 1 illustrates a proper

two-layer PCB layout for the SC624 and supporting

components. Following fundament al layout rules is

critical for achieving the performance specified in the

Electrical Characteristics table. The following guidelines

are recommended when developing a PCB layout:

• Place all bypass and decoupling capacitors —

C1, C2, CIN, COUT, CLDO1, CLDO2, and CBYP as

close to the device as possible.

• All charge pump current passes through VIN,

VOUT, and the bucket capacitor connection

pins. Ensure that all connections to these pins

make use of wide traces so that the resistive

drop on each connection is minimized.

• The thermal pad should be connected to the

ground plane using multiple vias to ensure

proper thermal connection for optimal heat

transfer.

GND

GND

• Make all ground connections to a solid

ground plane as shown in the example layout

(Figure 3).

• If a ground layer is not feasible, the following

groupings should be connected:

ƒ PGND — CIN, COUT

ƒ AGND — Ground Pad, CLDO1, CLDO2,

CBYP

• If no ground plane is available, PGND and

AGND should be routed back to the negative

battery terminal as separate signals using thick

traces. Joining the two ground returns at the

terminal prevents large pulsed return currents

from mixing with the low-noise return currents

of the LDOs.

• Both LDO output traces should be made as

wide as possible to minimize resistive losses.

CIN

C1

C2

COUT

C2-

PGND

NC

BL1

BL2

SC624

LDO1

LDO2

BYP

NC

SWIF

CLDO1

CLDO2

CBYP

Figure 2 — Layer 1

Figure 1 — Recommended PCB Layout

Figure 3 — Layer 2

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