WM8352 datasheet(130/336 Pages) WOLFSON

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WM8352

Production Data

PD, February 2011, Rev 4.4

130

A summary of the Mode Control and Voltage Control for DC-DC Converter 1 is provided in Table 76.

Note that “Hibernate” in Table 76 refers to a GPIO Hibernate input or to the applicable Hibernate

signal selected by the DC1_HIB_TRIG field.

The equivalent logic applies for DC-DC 3, 4 and 6. Note that the DC-DC Converters must also be

enabled as described in Table 71.

HIBERNATE DC1_HIB_MODE DC1_SLEEP DC1_ACTIVE

OPERATING

MODE

OUTPUT

VOLTAGE

Standby/Hysteretic

DC1_VSEL

Active

DC1_VSEL

LDO Mode

DC1_VSEL

000

Standby/Hysteretic

DC1_VSEL

Active

DC1_VSEL

LDO Mode

DC1_VSEL

001

Standby/Hysteretic

DC1_VIMG

Active

DC1_VIMG

LDO Mode

DC1_VIMG

010

Standby/Hysteretic

DC1_VSEL

011

Standby/Hysteretic

DC1_VIMG

100

LDO Mode

DC1_VSEL

101

LDO Mode

DC1_VIMG

110

Disabled

N/A

111

Disabled

N/A

Table 76 DC1 Converter Operating Mode Selection

14.6.4

DC-DC BOOST (STEP-UP) CONVERTER CONTROL

DC-DC Converters 2 and 5 are boost converters which can be configured to operate in different

operating modes, using the register bits described in Table 77.

In Switch mode, the DC-DC Converter acts as a switch between VP2 and L2 or between VP5 and L5

for Converter 2 and 5 respectively. The switch is enabled (closed) by setting DCn_ENA = 1. The

switch is disabled (opened) by setting DCn_ENA = 0. Note that the switch voltage source on VP2 or

VP5 must be >1.2V to ensure reliable operation.

In Boost mode, the DC-DC Converters operate as step-up converters, employing current-mode

architecture, capable of powering LED lights. The output voltage can be higher than the input

voltage, but cannot be lower. Different configurations of voltage feedback are available in boost

mode, to control the output voltage in different ways. The voltage feedback mode is selected by the

DCn_FBSRC register field.

When DCn_FBSRC = 00, the converter’s output voltage is set by two external resistors connected to

FB2 or FB5. See Section 29 for Applications Information covering the selection of suitable

components.

When DCn_FBSRC = 01, the converter uses the ISINKA pin as feedback and adjusts its output

voltage in order to achieve the required ISINKA current.

When DCn_FBSRC = 10, the converter uses the ISINKB pin as feedback and adjusts its output

voltage in order to achieve the required ISINKB current.

When DCn_FBSRC = 11, the converter’s output voltage is set by two internal resistors, resulting in a

fixed 5V output, suitable for USB interfaces.

The current-controlled configurations using ISINKA or ISINKB are intended for controlling a string of

serially-connected LEDs driven by one of the DC-DC boost converters. See Table 97 for a definition

of the CSn_ISEL register field which determines the required ISINKA or ISINKB current. In these

modes, external resistors connected on the FB2 or FB5 pin determine the maximum output voltage.

See Section 29 for Applications Information covering the selection of suitable components.

WM8352 Datasheet(PDF) 130 Page - Wolfson Microelectronics plc

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