Texas Instruments LM3242 6MHz, 750mA Miniature, Adjustable, Step-Down DC-DC EVM LM3242TM-EV/NOPB LM3242TM-EV/NOPB 데이터 시트

제품 코드

LM3242TM-EV/NOPB

SNOSB48D – OCTOBER 2011 – REVISED MARCH 2013

for minimum footprint and best high frequency characteristics.

Figure 33. LM3242 Recommended Parts Placement (Top View)

Component Placement
•

PVIN

1. Use a star connection from PVIN to LM3242 and PVIN to PA VBATT connection (V

CC1

). Do not daisy-

chain PVIN connection to LM3242 circuit and then to PA device PVIN connection.

•

TOP LAYER

1. Place a via in LM3242 SGND(A2), BPEN(C1) pads to drop and connect directly to System GND Layer 4.

2. Place two vias at LM3242 SW solder bump to drop VSW trace to Layer 3.

3. Connect C2 and C3 capacitor GND pads to PGND bump on LM3242 using a star connection. Place vias

in C2 and C3 GND pads that connect directly to System GND Layer 4.

4. Add 01005/0201 capacitor footprints (C1,C4) to input/output of LM3242 for improved high frequency

filtering. C1 and C4 GND pads connect directly to System GND Layer 4.

5. Place three vias at L1 inductor pad to bring up VSW trace from Layer 3 to top Layer.

•

LAYER 2

1. Make FB trace at least 10 mils (0.254 mm) wide.

2. Isolate FB trace away from noisy nodes and connect directly to C3 output capacitor. Place a via in

LM3242 SGND(A2), BPEN(C1) pads to drop and connect directly to System GND Layer 4.

•

LAYER 3

1. Make VSW trace at least 15 mils (0.381mm) wide.

•

LAYER 4 (System GND

1. Connect C2 and C3 PGND vias to this layer.

2. Connect C1 and C4 GND vias to this layer.

3. Connect LM3242 SGND(A2), BPEN(C1), NC(B2) pad vias to this layer.

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