WM8350GEB/V Wolfson Microelectronics, WM8350GEB/V Datasheet - Page 160

• Manufacturer Part Number: WM8350GEB/V
• Description: Audio CODECs Audio CODEC plus pwr management
• Manufacturer: Wolfson Microelectronics

Specifications of WM8350GEB/V

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

WM8350
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The WM8350 monitors the battery status via the AUX1 pin and by voltage/current sensing on other
pins. See Section 17.7.7 for details of the battery fault conditions and reporting.
If the application is intended to run without a battery present, then it is recommended that a 3.3μF
capacitor be placed on the BATT pin to ensure correct charger behaviour. Also, the SWRTC pin
should be left floating, to avoid leakage in BACKUP mode as described in Section 17.6. The Battery
Charger interrupts should also be masked, as these will be invalid - see Section 17.7.8 for details of
the Battery Charger Interrupts. It is recommended that the Battery Charger also be disabled in this
case - note that the Battery Charger is enabled by default, including on entry to the OFF power state.
A typical battery charge cycle is illustrated in Figure 77. This shows both the trickle charge and fast
charge processes.
The trickle charge mode is a constant current mode. Trickle charging is enabled when the battery
voltage falls below a charging threshold voltage; it is disabled when the charge current falls to a
programmable ‘End of Charge’ threshold level.
Fast charging consists of two phases:
In the constant current phase, the WM8350 drives a programmable constant current into the battery
through the BATT pin. During this phase, the battery voltage rises monotonically until the battery
reaches the target voltage.
When the battery reaches the target voltage, the charger enters the constant voltage phase, in which
the WM8350 regulates BATT to the target voltage. To achieve this, the WM8350 adjusts the charge
current adaptively. The charge current decreases monotonically over time. Fast charging is disabled
when the current falls to a programmable ‘End of Charge’ threshold level.
Figure 77 A Typical Charge Cycle
17.7.2
The battery charger is enabled by default when the WM8350 is in the ACTIVE, HIBERNATE or OFF
states. Note that battery charging is only possible when the selected power source is within normal
operating limits (see Section 7.5) and is more than 100mV higher than the battery voltage.
The battery charger can be disabled by setting the CHG_ENA register bit to ‘0’. When the battery
charger is enabled, it autonomously checks if the conditions for charging are fulfilled and controls the
charging processes accordingly. The status of the battery charger can be read from the
CHG_ACTIVE register bit. (Note this bit is read-only.)
The battery charger can be paused by writing to the CHG_PAUSE register bit. This provides a simple
option to halt the battery charger and to subsequently restart it without affecting the charge timer or
other settings.
BATTERY CHARGER ENABLE
PD, March 2010, Rev 4.2
Production Data
160