WM8310 datasheet(67/291 Pages) CIRRUS

67 / 291 page

Pre-Production

WM8310

PP, May 2012, Rev 3.1

15 POWER MANAGEMENT

15.1 GENERAL DESCRIPTION

The WM8310 provides 4 DC-DC Converters and 11 LDO Regulators. The DC-DC Converters

comprise 3 step-down (Buck) converters and 1 step-up (Boost) converter. The Regulators comprise

general purpose LDOs (LDO1 - LDO6) and low-noise analogue LDOs (LDO7 - LDO10). The analogue

LDOs offer superior PSRR, noise and load-transient performance. LDO11 is a low power LDO

intended for powering “always on” circuits connected to the WM8310; this LDO can be configured to

remain enabled in the OFF state.

These power management components are designed to support application processors and

associated peripherals. DC-DC1 and DC-DC2 are intended to provide power to the processor voltage

domains; DC-DC3 is suitable for powering memory circuits or for use as a pre-regulator for the LDOs.

The output voltage of each of the buck converters and regulators is programmable in software

through control registers.

The WM8310 can execute programmable sequences of enabling and disabling the DC-DC Buck

Converters and LDO Regulators as part of the transitions between the ON, OFF and SLEEP power

states. The WM8310 power management circuits can also interface with configurable hardware

control functions supported via GPIO pins. These include GPIO inputs for selecting alternate voltages

or operating modes, and GPIO outputs for controlling external power management circuits.

The configuration of the power management circuits, together with some of the GPIO pins and other

functions, may be stored in the integrated OTP memory. This avoids any dependence on a host

processor to configure the WM8310 at start-up. See Section 14 for details of the OTP memory.

15.2 DC-DC CONVERTER AND LDO REGULATOR CONTROL

The integrated DC-DC Converters and LDO Regulators can each be enabled in the ON or SLEEP

power states by setting the DCm_ENA or LDOn_ENA bits as defined in Section 15.12.1. Note that

setting the DCm_ENA or LDOn_ENA bits in the OFF state will not enable the DC-DC Converters or

LDO Regulators. These bits should not be written to when the WM8310 is in the OFF state; writing to

these bits in the OFF state may cause a malfunction.

In many applications, there will be no need to write to the DCm_ENA or LDOn_ENA bits, as these bits

are controlled by the WM8310 when a power state transition is scheduled. Dynamic, run-time control

of the DC-DC Converters or LDO Regulators is also possible by writing to these registers. Note that

the DC-DC4 Boost Converter cannot be configured as part of the power state transitions; this

Converter must always be enabled by writing to the DC4_ENA bit.

The DC-DC Converters and LDO Regulators can be assigned to a Hardware Enable (GPIO) input for

external enable/disable control. In this case, the converter or regulator is not affected by the

associated DCm_ENA or LDOn_ENA bits. See Section 15.3 for further details.

The WM8310 can also control other circuits, including external DC-DC Converters or LDO Regulators

using the External Power Enable (EPE) outputs. The External Power Enable outputs are alternate

functions supported via GPIO - see Section 21. The External Power Enable outputs can be controlled

in the same way as the internal DC-DC Converters and LDO Regulators. The associated control bits

are EPE1_ENA and EPE2_ENA, as defined in Section 15.12.1.

LDO Regulator 11 is a Low Power LDO Regulator, which is configured differently to the other LDOs. It

is a low-power LDO intended for “Always-On” functions external to the WM8310 and can be enabled

when the WM8310 is in the OFF power state.

When LDO11_FRCENA is set, then LDO11 is enabled at all times in the OFF, ON and SLEEP states.

Note that LDO11 is always disabled in the BACKUP and NO POWER states. See Section 15.12.4 for

the definition of LDO11_FRCENA.

The current commanded state of each of the DC-DC Converters, LDO Regulators and EPE outputs is

indicated in the DCm_STS, LDOn_STS and EPEn_STS register bits.

If a fault condition causes any converter or regulator to be disabled, then the associated _ENA and

_STS fields are reset to 0.

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