ADVANCE
CYW43570
2.5 Power-Off Shutdown
The CYW43570 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 CYW43570 is not needed in the system, VDDIO_RF and VDDC are shut down while
VDDIO remains powered. This allows the CYW43570 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 CYW43570, 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 CYW43570 to be fully integrated in an embedded device and
take full advantage of the lowest power-savings modes.
When the CYW43570 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.
2.6 Power-Up/Power-Down/Reset Circuits
The CYW43570 has two signals (see Table 3) 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.
Table 3. Power-Up/Power-Down/Reset Control Signals
Signal
WL_REG_ON
Description
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 CYW43570 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 kW 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 CYW43570 regulators. If BT_REG_ON and WL_REG_ON are low, the regulators will be
disabled. This pin has an internal 200 kW pull-down resistor that is enabled by default. It can be
disabled through programming.
Document Number: 002-15054 Rev. *I
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