bc41b143a07 ETC-unknow, bc41b143a07 Datasheet - Page 67

• Manufacturer Part Number: bc41b143a07
• Description: Single Chip Bluetooth
• Manufacturer: ETC-unknow

For Class 1 Bluetooth applications, the USB power descriptor should be altered to reflect the amount of power
required. This is accomplished by setting PSKEY_USB_MAX_POWER (0x2c6). This is higher than for a Class 2
application due to the extra current drawn by the Transmit RF PA.
When selecting a regulator, be aware that VBUS may go as low as 4.4V. The inrush current (when charging reservoir
and supply decoupling capacitors) is limited by the USB specification. See USB Specification v1.1, section 7.2.4.1.
Some applications may require soft start circuitry to limit inrush current if more than 10µF is present between VBUS
and GND.
The 5V VBUS line emerging from a PC is often electrically noisy. As well as regulation down to 3.3V and 1.8V,
applications should include careful filtering of the 5V line to attenuate noise that is above the voltage regulator
bandwidth. Excessive noise on the 1.8V supply to the analogue supply pins of BlueCore4-ROM will result in reduced
receive sensitivity and a distorted RF transmit signal.
9.5.6
All USB devices must permit the USB controller to place them in a USB suspend mode. While in USB Suspend,
bus-powered devices must not draw more than 0.5mA from USB VBUS (self-powered devices may draw more than
0.5mA from their own supply). This current draw requirement prevents operation of the radio by bus-powered devices
during USB Suspend.
The voltage regulator circuit itself should draw only a small quiescent current (typically less than 100µA) to ensure
adherence to the suspend current requirement of the USB specification. This is not normally a problem with modern
regulators. Ensure that external LEDs and/or amplifiers can be turned off by BlueCore4-ROM. The entire circuit must
be able to enter the suspend mode. Refer to separate CSR documentation for more details on USB Suspend.
9.5.7
BlueCore4-ROM can provide out-of-band signalling to a host controller by using the control lines called USB_DETACH
and USB_WAKE_UP. These are outside the USB specification (no wires exist for them inside the USB cable), but can
be useful when embedding BlueCore4-ROM into a circuit where no external USB is visible to the user. Both control
lines are shared with PIO pins and can be assigned to any PIO pin by setting PSKEY_USB_PIO_DETACH and
PSKEY_USB_PIO_WAKEUP to the selected PIO number.
USB_DETACH is an input which, when asserted high, causes BlueCore4-ROM to put USB_DN and USB_DP in a high
impedance state and turns off the pull-up resistor on DP. This detaches the device from the bus and is logically
equivalent to unplugging the device. When USB_DETACH is taken low, BlueCore4-ROM will connect back to USB
and await enumeration by the USB host.
CS-101564-DSP12
Suspend Current
Detach and Wake_Up Signalling
Figure 9.12: USB Connections for Bus-Powered Mode
BlueCore
USB_DN
USB_ON
USB_DP
Production Information
© CSR plc 2003-2007
Regulator
Voltage
R
R
R
vb1
s
s
D-
D+
VBUS
GND
Device Terminal Descriptions
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