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Power-Off Shutdown

BCM4354 Data Sheet

BROADCOM CONFIDENTIAL

Broadcom®

October 15, 2014 • 4354-DS109-R

Page 26

Power-Off Shutdown

The BCM4354 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 BCM4354 is not needed in the system,

VDDIO_RF and VDDC are shut down while VDDIO remains powered. This allows the BCM4354 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 a low-power shut-down state, provided VDDIO remains applied to the BCM4354, all outputs are tristated,

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

BCM4354 to be fully integrated in an embedded device and take full advantage of the lowest power-savings

modes.

When the BCM4354 is powered on from this state, it is the same as a normal power-up and the device does not

retain any information about its state from before it was powered down.

Power-Up/Power-Down/Reset Circuits

The BCM4354 has two signals (see Table 2) that enable or disable the Bluetooth and WLAN circuits and the

internal regulator blocks, allowing the host to control power consumption. For timing diagrams of these signals

and the required power-up sequences, see Section 21: “Power-Up Sequence and Timing,” on page 180.

Table 2: Power-Up/Power-Down/Reset Control Signals

Signal

Description

WL_REG_ON This signal is used by the PMU (with BT_REG_ON) to power up the WLAN section. It is also

OR-gated with the BT_REG_ON input to control the internal BCM4354 regulators. When this

pin is high, the regulators are enabled and the WLAN section is out of reset. When this pin is

low, the WLAN section is in reset. If BT_REG_ON and WL_REG_ON are both low, the

regulators are disabled. This pin has an internal 200 kΩ pull-down resistor that is enabled by

default. It can be disabled through programming.

BT_REG_ON

This signal is used by the PMU (with WL_REG_ON) to decide whether or not to power down

the internal BCM4354 regulators. If BT_REG_ON and WL_REG_ON are low, the regulators

will be disabled. This pin has an internal 200 kΩ pull-down resistor that is enabled by default.

It can be disabled through programming.

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