wm8350 Wolfson Microelectronics plc, wm8350 Datasheet - Page 129

• Manufacturer Part Number: wm8350
• Description: Wolfson Audioplus? Stereo Codec With Power Management
• Manufacturer: Wolfson Microelectronics plc

Production Data
w
14.6.2
The DC-DC converters are controlled by an internally generated clock signal from the RC Oscillator
with a constant frequency of around 2.048MHz for DC-DC 1, 3, 4 and 6, and a constant frequency of
around 1.024MHz for DC-DC 2 and 5.
14.6.3
DC-DC Converters 1, 3, 4 and 6 are buck converters which can be configured to operate in different
operating modes using the register bits described in Table 71.
In Active mode, the DC-DC Converters operate to their highest level of performance. The DC-DC
Converters will automatically select PWM or Pulse-Skipping operation according to the load
condition. This enables the power efficiency to be maximised across a wide range of load conditions.
It is possible to force the Converters to use the higher performance PWM mode; in this mode, pulse-
skipping is disabled and the output voltage is regulated by switching at a constant frequency which
improves the transient response at light loads.
In Standby/Hysteretic Mode, the DC-DC Converters disable some of the internal control circuitry in
order to reduce power consumption. The load regulation may be degraded in this mode of operation.
The efficiency data in Section 9.2.1 shows the conditions under which Standby Mode can offer better
efficiency than Active Mode.
In LDO Mode, the DC-DC Converters are reconfigured as low power LDOs.
When DCn_SLEEP = 0, the corresponding DCn_ACTIVE register bit selects between Active and
Standby/Hysteretic modes for the associated DC-DC converter.
The DCn_SLEEP register bits control the selection of LDO Mode. Setting DCn_SLEEP = 1 selects
LDO Mode. This bit takes precedence over the corresponding DCn_ACTIVE bit.
R177 (B1h)
DC-DC Active
Options
R178 (B2h)
DC-DC Sleep
Options
Note: n is either 1, 3, 4 or 6 and identifies the individual DC-DC converter
R248 (F8h)
DCDC1 Test
Controls
R250 (FAh)
DCDC3 Test
Controls
R251 (FBh)
DCDC4 Test
Controls
R253 (FDh)
DCDC4 Test
Controls
Table 71 Operating Mode Control for DC-DC Converters 1, 3, 4 and 6
ADDRESS
CLOCKING
DC-DC BUCK (STEP-DOWN) CONVERTER CONTROL
BIT
0
2
3
5
0
2
3
5
4
4
4
4
DC1_ACTIVE
DC3_ACTIVE
DC4_ACTIVE
DC6_ACTIVE
DC1_SLEEP
DC3_SLEEP
DC4_SLEEP
DC6_SLEEP
DC1_FORCE_
PWM
DC3_FORCE_
PWM
DC4_FORCE_
PWM
DC6_FORCE_
PWM
LABEL
DEFAULT
1
1
1
1
0
0
0
0
0
0
0
0
DC-DCn Active mode
0 = Select Standby mode
1 = Select Active mode
DC-DCn Sleep Mode
0 = Normal DC-DC operation
1 = Select LDO mode
Force DC-DC1 PWM mode
0 = Normal DC-DC operation
1 = Force DC-DC PWM mode
Force DC-DC3 PWM mode
0 = Normal DC-DC operation
1 = Force DC-DC PWM mode
Force DC-DC4 PWM mode
0 = Normal DC-DC operation
1 = Force DC-DC PWM mode
Force DC-DC6 PWM mode
0 = Normal DC-DC operation
1 = Force DC-DC PWM mode
DESCRIPTION
PD, June 2009, Rev 4.1
WM8350
129