WM8311 datasheet(73/302 Pages) WOLFSON

73 / 302 page

Pre-Production

WM8311

PP, May 2012, Rev 3.1

The operating mode of the LDO Regulators in the ON power state is selected using the

LDOn_ON_MODE register fields. The operating mode of the LDO Regulators in the SLEEP power

state is selected using the LDOn_SLP_MODE register fields.

For the standard LDOs, LDO1 - LDO5, two different Low Power modes are provided, offering limited

load current capability and reduced quiescent current. When Low Power mode is selected in the ON

or SLEEP power states, then the LDOn_LP_MODE register bits determine which Low Power mode is

selected.

Note that the operating mode and output voltage of the LDO Regulators may also be controlled by the

Hardware Control inputs. The Hardware Control inputs are alternate functions supported via GPIO.

See Section 15.9 for details of Hardware Control.

15.5 OUTPUT VOLTAGE CONTROL

15.5.1 DC-DC SYNCHRONOUS BUCK CONVERTERS

The output voltage of the DC-DC Converters 1-3 in the ON power state is selected using the

DCm_ON_VSEL register fields. The output voltage of these converters in the SLEEP power state is

selected using the DCm_SLP_VSEL register fields.

DC-DC Converters 1 and 2 support two different switching frequencies, as described in Section 15.6.

Note that the supported output voltage range for these converters is restricted in the 4MHz mode; for

output voltages greater than 1.4V, the 2MHz mode must be used.

The DC-DC Converters are dynamically programmable - the output voltage may be adjusted in

software at any time. These converters are step-down converters; their output voltage can therefore

be lower than the input voltage, but cannot be higher.

Note that the output voltage of DC-DC Converters 1 and 2 may also be controlled using the Dynamic

Voltage Scaling features described in Section 15.6. Software control (using register writes) and

hardware control (using the Hardware DVS Control inputs supported via GPIO) is supported.

Note that the output voltage of the DC-DC Converters may also be controlled by the Hardware

Control inputs. The Hardware Control inputs are alternate functions supported via GPIO. See

Section 15.9 for details of Hardware Control.

When changing the output voltage of DC-DC Converters 1 and 2, the GPIO output “DC-DCm DVS

Done” can be used to confirm the DVS Control has completed; see Section 15.6 for details.

15.5.2 DC-DC BOOST CONVERTERS

The output voltage of the DC-DC4 Boost Converter is set as described in Section 15.4.3. The voltage

is not commanded directly, but is regulated automatically by the WM8311 in order to support the

current that has been commanded for the selected Current Sink (ISINK).

15.5.3 LDO REGULATORS 1-5 AND LDO7

The output voltage of the LDO Regulators 1-5 and 7 in the ON power state is selected using the

LDOn_ON_VSEL register fields. The output voltage of the LDO Regulators in the SLEEP power state

is selected using the LDOn_SLP_VSEL register fields.

The LDO Regulators are dynamically programmable - the output voltage may be adjusted in software

at any time.

Note that the output voltage of the LDO Regulators may also be controlled by the Hardware Control

inputs. The Hardware Control inputs are alternate functions supported via GPIO. See Section 15.9 for

details of Hardware Control.

15.5.4 LDO REGULATOR 11

The output voltage of LDO11 can be set in two ways - it can be commanded directly, or it can be

commanded to follow the DC-DC Converter 1 output voltage.

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