WM8321
Production Data
15.4 OPERATING MODE CONTROL
15.4.1 DC-DC SYNCHRONOUS BUCK CONVERTERS
The DC-DC Converters DC-DC1 - DC-DC4 can be configured to operate in four different operating
modes. The operating modes are summarised in Table 30. For more detailed information on the DC-
DC (Buck) Converter operating modes, see Section 15.14.2.
DC-DC CONVERTER
OPERATING MODE
DESCRIPTION
Forced Continuous Conduction
Mode (FCCM)
High performance mode for all static and transient load
conditions.
Auto Mode: Continuous /
Discontinuous Conduction with
Pulse-Skipping Mode (CCM/DCM
with PS)
High efficiency mode for all static and transient load
conditions. Performance may be less than FCCM mode for
heavy load transients.
Hysteretic Mode
High efficiency mode for light static and light transient loads
only. Maximum load current is restricted; output voltage ripple
is increased.
LDO Mode
Power saving mode for light loads only. High efficiency for
ultra light loads. Low current soft-start control.
Table 30 DC-DC Synchronous Buck Converter Operating Modes
The operating mode of the DC-DC Converters in the ON power state is selected using the
DCm_ON_MODE register fields. The operating mode of the DC-DC Converters in the SLEEP power
state is selected using the DCm_SLP_MODE register fields.
When changing the operating mode of the DC-DC Converters in preparation for an increased load, a
set-up time of 100s should be allowed for the operating mode to be established before applying the
new load.
Note that the operating mode 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 15.8 for details of Hardware Control.
15.4.2 LDO REGULATORS
The LDO Regulators LDO1 - LDO10 can be configured to operate in Normal operating mode or in
Low Power mode.
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 - LDO6, 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 15.8 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 1-4 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.
PD, February 2012, Rev 4.0
64
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
