BCM4325
Preliminary Data Sheet
6/30/09
RF POWER MANAGEMENT
The BBC generates power-down control signals for the transmit path, receive path, PLL, and power amplifier to the 2.4 GHz
transceiver. The transceiver then processes the power-down functions accordingly.
HOST CONTROLLER POWER MANAGEMENT
When running in UART mode, the BCM4325 may be configured so that dedicated signals are used for power management
hand shaking between the BCM4325 and the host. The basic power saving functions supported by those handshaking
signals include the standard Bluetooth defined power savings modes and standby modes of operation.
An alternative to using the BT_WAKE and HOST_WAKE signalling uses the CTS and RTS as a combination of UART
handshake signals during normal operation and as BT_WAKE and HOST_WAKE when the device is in a power saving
mode.
Table 4 describes the power control handshake signals used with the UART interface.
Table 4: Power Control Pin Description
Mapped to
Signal
Type Description
Pin
BT_WAKE
BT_GPIO_0
I
Bluetooth device wakeup. Signal from the host to the BCM4325 indicating that the
host requires attention.
• Asserted: Bluetooth device must wakeup or remain awake.
• Deasserted: Bluetooth device may sleep when sleep criteria are met.
The polarity of this signal is software configurable and can be asserted high or low.
HOST_WAKE BT_GPIO_1
O
Host wake up. Signal from the BCM4325 to the host indicating that the BCM4325
requires attention.
• Asserted: Host device must wakeup or remain awake.
• Deasserted: Host device may sleep when sleep criteria are met.
The polarity of this signal is software configurable and can be asserted high or low.
Note: Successful operation of the power management handshaking signals requires coordination between the
BCM4325 firmware and the host software.
BBC POWER MANAGEMENT
The following are low power operations for the BBC:
•
•
Physical layer packet handling turns RF on and off dynamically within packet TX and RX.
Bluetooth-specified low-power connection modes are sniff, hold, and park. While in these modes, the BCM4325 runs on
the low-power oscillator and wakes up after a predefined time period.
FM POWER MANAGEMENT
The BCM4325 FM subsystem can operate independently of, or in tandem with, the Bluetooth RF and BBC subsystems. The
FM subsystem power management scheme operates in conjunction with the Bluetooth RF and BBC subsystems.
Broadcom Corporation
Page 16
Bluetooth Power Management Unit
Document 4325-DS04-R
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