BCM88335 Data Sheet
Power-Off Shutdown
Power-Off Shutdown
The BCM88335 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 BCM88335 is not needed in the system,
VDDIO_RF and VDDC are shut down while VDDIO remains powered. This allows the BCM88335 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, the provided VDDIO remains applied to the BCM88335, all outputs are
tristated, and most input 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 BCM88335 to be fully integrated in an embedded device and take full advantage of the lowest
power-savings modes.
When the BCM88335 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 BCM88335 has two signals (see Table 1) 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 19: “Power-Up Sequence and Timing,” on page 132.
Table 1: 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 BCM88335 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 k 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 BCM88335 regulators. If BT_REG_ON and WL_REG_ON are low, the regulators
will be disabled. This pin has an internal 200 k pull-down resistor that is enabled by default.
It can be disabled through programming.
Broadcom®
September 23, 2015 • 88335-DS100-R
Page 25
BROADCOM CONFIDENTIAL
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