wm8351 Wolfson Microelectronics plc, wm8351 Datasheet - Page 134

• Manufacturer Part Number: wm8351
• Description: Wolfson Audioplus? Stereo Codec With Power Management
• Manufacturer: Wolfson Microelectronics plc

WM8351
14.7 CONFIGURING THE LDO REGULATORS
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The configuration of the LDO Regulators is described in the following sections. Some of the control
fields form part of the Custom Mode configuration settings and therefore will not require to be set in
software in some applications.
14.7.1
The LDO Regulators can be enabled in software using the register fields defined in Table 81. To
reduce supply in-rush current, individual regulators should be programmed to start in different time
slots within the start-up sequence.
In the WM8351 ACTIVE state, the LDO Regulators can be enabled in software using the LDOn_ENA
bits. Setting these bits whilst in the Pre-Active state (see Figure 65) will not immediately enable the
corresponding LDO Regulators; these bits will only become effective once the WM8351 has reached
the ACTIVE state.
Each Regulator may be programmed to switch on in a selected timeslot within the start-up sequence.
The WM8351 will set the LDOn_ENA field for any LDO Regulator that is enabled during the start-up
sequence. Note that setting the LDOn_ENSLOT fields in software is only relevant to the
Development Mode, as these fields are assigned preset values in each of the Custom Modes.
Each Regulator may be programmed to switch off in a selected timeslot within the shutdown
sequence. If a Regulator is not allocated to one of the 14 shutdown timeslots, it will be disabled when
the WM8351 enters the OFF state.
R13 (0Dh) or
R176 (B0h)
DC-DC / LDO
requested
Note: These bits can be accessed through R13 or through R176. Reading from or writing to either
register location has the same effect.
R201 (C9h)
for LDO1
R204 (CCh)
ADDRESS
LDO REGULATOR ENABLE
13:10
BIT
10
11
8
9
LDO1_ENA
LDO2_ENA
LDO3_ENA
LDO4_ENA
LDOn_ENSL
OT [3:0]
LABEL
DEFAULT
0000
0
0
0
0
LDO1 enable
0 = disabled
1 = enabled
Note: internal conditions may prevent the
converter from actually switching on -
see DCDC/LDO Status register for actual
converter status.
LDO2 enable
0 = disabled
1 = enabled
Note: internal conditions may prevent the
converter from actually switching on -
see DCDC/LDO Status register for actual
converter status.
LDO3 enable
0 = disabled
1 = enabled
Note: internal conditions may prevent the
converter from actually switching on -
see DCDC/LDO Status register for actual
converter status.
LDO4 enable
0 = disabled
1 = enabled
Note: internal conditions may prevent the
converter from actually switching on -
see DCDC/LDO Status register for actual
converter status.
Time slot for LDOn start-up
0000 = Disabled (do not start up)
0001 = Start-up in time slot 1
… (total 14 slots available)
DESCRIPTION
PD, June 2009, Rev 4.1
Production Data
134