User's Manual

9/29/2004 OV4F2
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BCM2035 User Manual
04/23/03
Broadcom Corporation
Page 10 Bluetooth Baseband Core Document 2035-UM100-R
POWER MANAGEMENT UNIT
The Power Management Unit (PMU) provides power management features that can be invoked by either
software through power management registers, or packet handling in the baseband core. The following
sections are power management functions provided by the BCM2035.
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.
BBC Power Management
There are several 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: Sniff, Hold, and Park. While in these low-power connection
modes, the
BCM2035 runs on the Low Power Oscillator and wakes up after a pre-defined time period.
Lower Power Shutdown
The BCM2035 provides a Low Power Shutdown feature that allows the device to be turned off while the host,
and any other devices in the system, remain operational. When the BCM2035 is not needed in the system,
VDD_RF and VDD_CORE are shut down while VDD_IO is left powered. This allows the BCM2035 to be
effectively off while keeping the I/O pins powered so that they do not draw extra current from any other devices
connected to the I/O.
During low power shutdown state, as long as VDD_IO remained applied to the
BCM2035, all outputs are tri-
stated and most inputs signals are disabled. Input voltages must remain within the limits defined for normal
operation. This is done to prevent current paths or create loading on any digital signals in the system, and
enables the
BCM2035 to be fully integrated in an embedded device and take full advantage of the lowest power
savings modes.
Two signals on BCM2035, the frequency reference input (XTAL_IN) and external LPO input (LPO_IN), are
designed to be high impedance inputs that will not load down the driving signal regardless of if the chip has
VDD_IO power applied to it or not.
When the BCM2035 is powered on from this state, it is the same as a normal power-up and the device does
not contain any information about its state before being powered-down.