AN2713 datasheet(21/40 Pages) STMICROELECTRONICS

21 / 40 page

AN2713

Layout guidelines

Doc ID 14431 Rev 1

21/40

Layout guidelines

Due to high current levels and fast switching waveforms, which radiate noise, a proper

printed circuit board (PCB) layout is essential. Sensitive analog grounds can be protected by

using a star ground configuration. Also, lead lengths should be minimized to reduce stray

capacitance, trace resistance, and radiated noise. Ground noise can be minimized by

connecting GND, the input bypass capacitor ground lead, and the output filter capacitor

ground lead to a single point (star ground configuration). Place input bypass capacitors (C1,

C2, C7 and C8) as close as possible to Vcc and GND, and the DC-DC output capacitors

(C3, C4, C5 and C6) as close as possible to VUP. Excessive noise at the Vcc input may

falsely trigger the undervoltage circuitry, resetting the I2C internal registers. If this occurs,

the registers are set to zero and the LNBH23 is put into shutdown mode.

LNB power supply demonstration boards are available for each package option through

order codes STEVAL-CBL003V1 (Figure 10) and STEVAL-CBL005V1 (Figure 11).

Figure 10.

STEVAL-CBL003V1 demonstration board photo (PowerSSO-24 package)

Figure 11.

STEVAL-CBL005V1 demonstration board photo (QFN32 package)

AN2713 Datasheet(PDF) 21 Page - STMicroelectronics