wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 146

• Manufacturer Part Number: wm8400
• Description: Wolfson Audioplustm Hi-fi Audio Codec And Power Management Unit For Mobile Multimedia
• Manufacturer: Wolfson Microelectronics plc

WM8400
w
DC-DC CONVERTER SOFT START
A soft start feature may be enabled on either of the DC-DC Converters, in order to limit the in-rush
current when they are enabled. When a converter is enabled with soft-start selected, a current limit
will initially be applied to the DC-DC Converter output. This current limit will be increased up to the
maximum current in three stages. The register fields in Table 92 control the duration of the three
stages. Therefore, when soft-start is enabled, the full start-up time for that DC-DC Converter will be 3
x Soft Start time.
Table 92 DC-DC Converter Soft Start
UNDERVOLTAGE DETECTION
Each DC-DC Converter and LDO Regulator is monitored for voltage accuracy. An Undervoltage
condition is set if the voltage falls below 95% of the required level. The action taken in response to an
Undervoltage condition can be set independently for each DC-DC Converter and each LDO
Regulator, as described in Table 93.
Table 93 Undervoltage Detection Control
R70 (46h)
R72 (48h)
R65 (41h)
R66 (42h)
R67 (43h)
R68 (44h)
R70 (46h)
R72 (48h)
REGISTER
ADDRESS
REGISTER
ADDRESS
BIT
11
11
11
11
11
11
BIT
9:8
9:8
LDO1_ERRACT
LDO2_ERRACT
LDO3_ERRACT
LDO4_ERRACT
DC1_ERRACT
DC2_ERRACT
DC1_SOFTST
[1:0]
DC2_SOFTST
[1:0]
LABEL
LABEL
DEFAULT
DEFAULT
00b
00b
0b
0b
0b
0b
0b
0b
LDO1 Undervoltage Error Action
0 = Generate IRQ only
1 = Generate IRQ, Assert NRST, De-
assert PWRGOOD, Shutdown device
LDO2 Undervoltage Error Action
0 = Generate IRQ only
1 = Generate IRQ, Assert NRST, De-
assert PWRGOOD, Shutdown device
LDO3 Undervoltage Error Action
0 = Generate IRQ only
1 = Generate IRQ, Assert NRST, De-
assert PWRGOOD, Shutdown device
LDO4 Undervoltage Error Action
0 = Generate IRQ only
1 = Generate IRQ, Assert NRST, De-
assert PWRGOOD, Shutdown device
DC1 Undervoltage Error Action
0 = Generate IRQ only
1 = Generate IRQ, Assert NRST, De-
assert PWRGOOD, Shutdown device
DC2 Undervoltage Error Action
0 = Generate IRQ only
1 = Generate IRQ, Assert NRST, De-
assert PWRGOOD, Shutdown device
DC1 Soft Start
00 = No soft start
01 = 400us steps
10 = 4ms steps
11 = 40ms steps
DC2 Soft Start
00 = No soft start
01 = 400us steps
10 = 4ms steps
11 = 40ms steps
DESCRIPTION
DESCRIPTION
PP, April 2009, Rev 3.0
Pre-Production
146