BCM20730 Datasheet, PDF (26/62 Pages) Cypress Semiconductor – Single-Chip Bluetooth Transceiver for Wireless Input Devices

BCM20730 Data Sheet
Clock Frequencies
The clock pin (SCL) and data pin (SDA) are both open-drain I/O pins. Pull-up resistors external to the BCM20730
are required on both the SCL and SDA pins for proper operation.
UART Interface
The UART is a standard 2-wire interface (RX and TX) and has adjustable baud rates from 9600 bps to 1.5 Mbps.
The baud rate can be selected via a vendor-specific UART HCI command. The interface supports the Bluetooth
3.0 UART HCI (H5) specification. The default baud rate for H5 is 115.2 kbaud.
Both high and low baud rates can be supported by running the UART clock at 24 MHz.
The BCM20730 UART operates correctly with the host UART as long as the combined baud rate error of the two
devices is within ±5%.
Clock Frequencies
The BCM20730 is set with crystal frequency of 24 MHz.
Crystal Oscillator
The crystal oscillator requires a crystal with an accuracy of ±20 ppm as defined by the Bluetooth specification.
Two external load capacitors in the range of 5 pF to 30 pF are required to work with the crystal oscillator. The
selection of the load capacitors is crystal dependent. Table 5 on page 26 shows the recommended crystal
specification.
Figure 6: Recommended Oscillator Configuration—12 pF Load Crystal
22 pF
20 pF
Crystal
XIN
XOUT
BROADCOM ®
September 9, 2013 • 20730-DS108-R
BROADCOM CONFIDENTIAL
Page 25