WM8311 datasheet(77/302 Pages) WOLFSON

77 / 302 page

Pre-Production

WM8311

PP, May 2012, Rev 3.1

The DC-DC3 Buck Converter has a selectable overvoltage protection feature, controlled by

DC3_OVP. This affects the converter response when DC3 is enabled or when its output voltage is

increased. When the overvoltage protection is enabled, there is less overshoot in the output voltage,

but some oscillation may occur as the voltage settles. This function should only be enabled if steep

load transients are present on the output of DC-DC3 and if the voltage overshoot is critical.

15.11 MONITORING AND FAULT REPORTING

Each of the DC-DC Converters (1 to 4) and LDOs (1 to 5 and 7) is monitored for voltage accuracy and

fault conditions. An undervoltage condition is detected if the voltage falls below the required level by

more than a pre-determined tolerance. If an undervoltage condition occurs, then this is indicated

using the corresponding status bit(s) defined in Section 15.12.6. An undervoltage condition also

triggers an Undervoltage Interrupt (see Section 15.13). Additional actions to shut down the converter

or perform a Device Reset may also be selected.

The Internal LDO (LDO13) is also monitored for voltage accuracy and fault conditions. An

undervoltage condition in LDO13 is indicated using the INTLDO_UV_STS bit. This undervoltage

condition also causes an OFF transition to be scheduled, as described in Section 11.3.

DC-DC Converters 1 and 2 are monitored for overvoltage conditions. An overvoltage condition is set if

the voltage is more than 100mV above the required level. If an overvoltage condition occurs, then this

is indicated using the corresponding status bit(s). Note that there is no Interrupt or other selectable

response to an overvoltage condition.

The current draw on DC-DC Converters 1 and 2 can be monitored against user-programmable

thresholds in order to detect a high current condition. This feature is enabled using

DCm_HC_IND_ENA and the current threshold is set using DCm_HC_THR. Note that the high current

threshold is not the same as the maximum current capability of the DC-DC Converters, but is set

according to the application requirements. If a high current condition occurs, then this is indicated

using the corresponding status bit(s). A high current condition also triggers a High Current Interrupt

(see Section 15.13).

15.12 POWER MANAGEMENT REGISTER DEFINITIONS

15.12.1 DC-DC CONVERTER AND LDO REGULATOR ENABLE

The Enable and Status register bits for the DC-DC Converters and LDO Regulators are defined in

Table 34.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R16464 (4050h)

DCDC Enable

3:0

DCm_ENA

DC-DCm Enable request

0 = Disabled

1 = Enabled

(Note that the actual status is indicated

in DCm_STS)

R16465 (4051h)

LDO Enable

10:0

LDOn_ENA

LDOn Enable request

0 = Disabled

1 = Enabled

(Note that the actual status is indicated

in LDOn_STS)

R16466 (4052h)

DCDC Status

3:0

DCm_STS

DC-DCm Status

0 = Disabled

1 = Enabled

R16467 (4053h)

LDO Status

10:0

LDOn_STS

LDOn Status

0 = Disabled

1 = Enabled

Notes:

n is a number (1-5, 7, 11) that identifies the individual LDO Regulator.

m is a number between 1 and 4 that identifies the individual DC-DC Converter.

Table 34 DC-DC Converter and LDO Regulator Control

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