IS1871 datasheet(37/44 Pages) MICROCHIP

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DS60001371C-Page 37

IS1870/71

APPENDIX B:

LAYOUT

GUIDELINES

B.1

RF Matching

The RF traces (including Tx, Rx, and antenna path) on

the PCB should match 50Ω impedance. In Figure A-1,

value of L1, L3, C1, C2, and C5 are fixed. The antenna

matching components C6, C7, and L2 should be

adjusted to match the 50Ω 2.4 GHz antenna.

B.2

PMU

The PMU section components, such as VBAT, BK_IN,

BK_O, BK_LX, AVDD, ULPC_O, CLDO_O, VREF

should be kept close to the IS1870/71.

For additional information on PCB design guidelines,

contact your local Microchip sales office. A list of Micro-

chip sales offices is given on the back page of this doc-

ument,.

The L4 and C14 of Buck section, shown in Figure A-1,

should be selected carefully. Capacitor C14 is either

4.7 μF/6.3V, X5R, or X7R type. The inductor L4 need to

be high current (IDC>300mA) and low DCR (<1Ω) type.

B.3

Crystal

The XI 32 MHz crystal specification should be within

the ±10 ppm range, see Figure A-1.

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