CC2531 Datasheet, PDF (22/32 Pages) Texas Instruments – A USB Enabled System-On-Chip Solution for 2.4-GHz IEEE 802.15.4 and ZigBee Applications

CC2531
SWRS086 – SEPTEMBER 2009 ........................................................................................................................................................................................ www.ti.com
APPLICATION INFORMATION
Few external components are required for the operation of the CC2531. A typical application circuit is shown in
Figure 17. For a complete USB certified reference design, see the CC2531 product page on www.ti.com. Typical
values and description of external components are shown in Table 2. The USB_P and USB_N pins need series
resistors R21 and R31 for impedance matching and the D+ line must have a pull-up resistor, R32. The series
resistors should match the 90 Ω ±15% characteristic impedance of the USB bus. Notice that the pull-up resistor
and the DVDD_USB must be connected to a voltage source between 3 and 3.6 V (typically 3.3 V). The voltage
source should be derived from or controlled by the VBUS power supply provided by the USB cable. In this way,
the pull-up resistor does not provide current to the D+ line when VBUS is removed. The pull-up resistor may be
connected directly between VBUS and the D+ line. As an alternative, if the CC2531 firmware needs the ability to
disconnect from the USB bus, a GPIO on the CC2531 can be used to control the pull-up resistor.
2.0V - 3.6V power supply
3.3V power supply
C401
Optional 32kHz crystal
C331
R32
R31
D+
C41
D-
R21
C31 C21
C321
1 DGND_USB
2 USB_P
3 USB_N
4 DVDD_USB
5 P1_5
6 P1_4
7 P1_3
8 P1_2
9 P1 1
10 DVDD2_
CC2531
DIE ATTACH PAD :
RBIAS 30
AVDD 4 29
AVDD 1 28
AVDD 2 27
RF_N 26
RF_P 25
AVDD 3 24
XOSC_Q2 23
XOSC_Q1 22
AVDD 5 21
R301
C251
C261
L252
C252
L261
C262
Antenna
(50 Ohm)
C254
C253 C255
XTAL
C221
C231
Power supply decoupling capacitors are not shown. Digital I / O not connected.
Figure 17. CC2531 Application Circuit
22
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