wm8351 Wolfson Microelectronics plc, wm8351 Datasheet - Page 159

• Manufacturer Part Number: wm8351
• Description: Wolfson Audioplus? Stereo Codec With Power Management
• Manufacturer: Wolfson Microelectronics plc

Production Data
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If the USB current limit cannot support the charge current demanded by CHG_TRICKLE_SEL and
USB current choking is enabled, then the charge current will be modified, where possible, in order to
continue charging. The trickle charge current cannot be controlled dynamically - the only possible
charge currents are 50mA or 100mA. Therefore, the only form of USB choking in trickle charge mode
is for a demanded current of 100mA to be reduced to 50mA. Trickle charge USB current choking is
controlled by the CHG_TRICKLE_USB_CHOKE register bit. The time constant for the charger’s
attempts to increase the current after USB choking can be controlled by CHG_RECOVERY_T.
The register control fields for Trickle Charging are described in Table 104. See Section 17.7.5 for
details of battery charger termination.
R168 (A8h)
Battery charger
control 1
R169 (A9h)
Battery charger
control 2
R170 (AAh)
Battery charger
control 3
Table 104 Trickle Charging Control
ADDRESS
BIT
9
8
7
6
7
CHG_TRICKLE
_TEMP_CHOK
E
CHG_TRICKLE
_USB_CHOKE
CHG_RECOVE
R_T
CHG_TRICKLE
_SEL
CHG_FRC
LABEL
DEFAULT
0
0
0
0
0
Enable trickle charge temperature
choking
0 = disable
1 = enable
Protected by security key.
Enable USB current choking in trickle
charge
0 = disable
1 = enable
Protected by security key.
Time constant adjust for charger choke
recovery (step-up):
0 = Step-up time constant is 180us
(allows faster recovery between
processor wakeups)
1 = Step-up time constant is >20ms
(outside audio band)
Protected by security key
Selects the trickle charge current.
0 = Set the trickle charge current to
50mA.
1 = Set the trickle charge current to
100mA.
Protected by security key.
Allows trickle-charging to be forced even
if the battery voltage is above the default
threshold
0 = only trickle-charge if the battery
voltage is below CHG_VSEL - 100mV
1 = always trickle-charge
Protected by security key.
DESCRIPTION
PD, June 2009, Rev 4.1
WM8351
159