WM8352
Production Data
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 105. See Section 17.7.5 for
details of battery charger termination.
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R168 (A8h)
9
CHG_TRICKLE
_TEMP_CHOK
E
0
Enable trickle charge temperature
choking
Battery charger
control 1
0 = disable
1 = enable
Protected by security key.
8
7
CHG_TRICKLE
_USB_CHOKE
0
0
Enable USB current choking in trickle
charge
0 = disable
1 = enable
Protected by security key.
CHG_RECOVE
R_T
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.
R169 (A9h)
6
7
CHG_TRICKLE
_SEL
0
0
Selects the trickle charge current.
Battery charger
control 2
0 = Set the trickle charge current to
50mA.
1 = Set the trickle charge current to
100mA.
Protected by security key.
R170 (AAh)
CHG_FRC
Allows trickle-charging to be forced even
if the battery voltage is above the default
threshold
Battery charger
control 3
0 = only trickle-charge if the battery
voltage is below CHG_VSEL - 100mV
1 = always trickle-charge
Protected by security key.
Table 105 Trickle Charging Control
PD, February 2011, Rev 4.4
160
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
