CC2538_15 Datasheet, PDF (19/33 Pages) Texas Instruments – Powerful Wireless Microcontroller System-On-Chip

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CC2538
SWRS096D – DECEMBER 2012 – REVISED APRIL 2015
6 Applications, Implementation, and Layout
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
Few external components are required for the operation of the CC2538xFnn. Figure 6-1 is a typical
application circuit. For a complete USB reference design, see the CC2538xFnn product page on
www.ti.com. Table 6-1 lists typical values and descriptions of external components. The USB_P and
USB_N pins require series resistors R21 and R31 for impedance matching, and the D+ line must have a
pullup resistor, R32. The series resistors should match the 90-Ω ±15% characteristic impedance of the
USB bus. Notice that the pullup resistor and DVDD_USB require connection to a voltage source between
3 V and 3.6 V (typically 3.3 V). To accomplish this, it is recommend to connect the D+ pull-up to a port/pin
that does not have an internal pullup (that is, PC0..3), instead of connecting it directly to a 3.3 V supply
(that is, software control of D+ pullup recommended).
2.0 V-3.6 V power supply
3.3 V power supply
C561
Optional 32 kHz crystal
C451
R31
D+
D-
R21
R32
C31 C21
C441
1 DGND_USB
2 USB_P
3 USB_N
4 DVDD_USB
5 PB0
6 PC7
7 PC6
8 PC5
9 PC4
10 VDD
11 PC3
12 PC2
13 PC1
14 PC0
CC2538
DIE ATTACH PAD:
Power supply decoupling capacitors are not shown
Digital I/O not connected
R_BIAS 42
AVDD 41
AVDD 40
AVDD 39
RF_N 38
RF_P 37
AVDD 36
XOSC32M_Q2 35
XOSC32M_Q1 34
AVDD 33
DCOUPL2 32
PD5 31
PD4 30
PD3 29
C281
R421
C382
C381
L381
C371
C372
L372
C321
C341
XTAL
C351
R281
RESET_N
Figure 6-1. CC2538xFnn Application Circuit
Antenna
(50 Ω)
L373
2 nH
L374
3.3 nH
C373
1.2 pF
Copyright © 2012–2015, Texas Instruments Incorporated
Applications, Implementation, and Layout
19
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