wm8400 Wolfson Microelectronics plc, wm8400 Datasheet - Page 144

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

WM8400
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DC-DC CONVERTER CURRENT LIMIT
In Active mode, the DC-DC Converters are primarily designed to operate up to 600mA. However, it is
possible to run the device for short periods of time with loads up to 1000mA. This feature is
controlled through register bits DC1_ACT_LIM and DC2_ACT_LIM.
It is important to note that currents in excess of 600mA may give rise to excessive temperatures
within the device. Care must be taken to ensure that the maximum junction temperature is not
exceeded - see “Thermal Characteristics”. It is recommended that the Current Limit register field be
returned to the 600mA setting when the device is not required to support exceptional load currents.
In DC-DC Converter Standby/Hysteretic mode, a different current limit is applied to the DC-DC
Converters. This limit is set by the DC1_STBY_LIM and DC2_STBY_LIM fields, in conjunction with
DC1_ACT_LIM and DC2_ACT_LIM. These fields are described in Table 90.
Note that, in Hibernate mode, the current limit is not programmable.
Table 90 DC-DC Converter Current Limit
R71 (47h)
R73 (49h)
REGISTER
ADDRESS
BIT
9:8
9:8
7
7
DC1_STBY_LIM
[1:0]
DC1_ACT_LIM
DC2_STBY_LIM
[1:0]
DC2_ACT_LIM
LABEL
DEFAULT
00b
00b
0b
0b
DC1 Standby Mode current limit
If DC1_ACT_LIM = 0:
00 = 70mA
01 = 150mA
10 = 300mA
11 = 600mA
If DC1_ACT_LIM = 1:
00 = 110mA
01 = 220mA
10 = 450mA
11 = 900mA
DC1 Active Mode current limit
0 = 600mA
1 = 1000mA
DC2 Standby Mode current limit
If DC2_ACT_LIM = 0:
00 = 70mA
01 = 150mA
10 = 300mA
11 = 600mA
If DC2_ACT_LIM = 1:
00 = 110mA
01 = 220mA
10 = 450mA
11 = 900mA
DC2 Active Mode current limit
0 = 600mA
1 = 1000mA
DESCRIPTION
PP, April 2009, Rev 3.0
Pre-Production
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