PRELIMINARY
CYW43438
2. Power Supplies and Power Management
2.1 Power Supply Topology
One Buck regulator, multiple LDO regulators, and a power management unit (PMU) are integrated into the CYW43438. All regulators
are programmable via the PMU. These blocks simplify power supply design for Bluetooth, WLAN, and FM functions in embedded
designs.
A single VBAT (3.0V to 4.8V DC maximum) and VDDIO supply (1.8V to 3.3V) can be used, with all additional voltages being provided
by the regulators in the CYW43438.
Two control signals, BT_REG_ON and WL_REG_ON, are used to power up the regulators and take the respective circuit blocks out
of reset. The CBUCK CLDO and LNLDO power up when any of the reset signals are deasserted. All regulators are powered down
only when both BT_REG_ON and WL_REG_ON are deasserted. The CLDO and LNLDO can be turned on and off based on the
dynamic demands of the digital baseband.
The CYW43438 allows for an extremely low power-consumption mode by completely shutting down the CBUCK, CLDO, and LNLDO
regulators. When in this state, LPLDO1 provides the CYW43438 with all required voltage, further reducing leakage currents.
Note: VBAT should be connected to the LDO_VDDBAT5V and SR_VDDBAT5V pins of the device.
Note: VDDIO should be connected to the WCC_VDDIO pin of the device.
2.2 CYW43438 PMU Features
The PMU supports the following:
■ VBAT to 1.35Vout (170 mA nominal, 370 mA maximum) Core-Buck (CBUCK) switching regulator
■ VBAT to 3.3Vout (250 mA nominal, 450 mA maximum 800 mA peak maximum) LDO3P3
■ 1.35V to 1.2Vout (100 mA nominal, 150 mA maximum) LNLDO
■ 1.35V to 1.2Vout (80 mA nominal, 200 mA maximum) CLDO with bypass mode for deep sleep
■ Additional internal LDOs (not externally accessible)
■ PMU internal timer auto-calibration by the crystal clock for precise wake-up timing from extremely low power-consumption mode.
Figure 3 and Figure 4 show the typical power topology of the CYW43438.
Document Number: 002-14796 Rev. *K
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