WM8311GEB/V Wolfson Microelectronics, WM8311GEB/V Datasheet - Page 110

• Manufacturer Part Number: WM8311GEB/V
• Description: POWER MANAGEMENT SUBSYSTEM, 121BGA
• Manufacturer: Wolfson Microelectronics

Specifications of WM8311GEB/V

• Supply Voltage: 5.5V
• No. Of Step-down Dc - Dc Converters: 4
• No. Of Ldo Regulators: 7
• Digital Ic Case Style: BGA
• No. Of Pins: 121
• No. Of Regulated Outputs: 9
• Operating Temperature Range: -40°C To
• Rohs Compliant: Yes
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

WM8311
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17.7.3 FAST CHARGING
Fast charging provides a faster way to charge the battery than is possible with trickle charge. See
Section 17.7.1 for a description of fast charging.
Fast charging mode is only possible under certain conditions. It is only possible when the selected
power source is Wall or when the USB current limit is set to 500mA or more. It is also required that
the battery voltage is above the fast charge voltage threshold; this ensures that fast charging is not
applied to a heavily discharged battery.
Fast charging is enabled by setting the CHG_FAST register bit, provided that the conditions for fast
charging are satisfied. The fast charge current limit is selected using the CHG_FAST_ILIM field.
The battery charge current is automatically controlled, up to a maximum set by CHG_FAST_ILIM.
The current is automatically limited when required if the battery is fully charged, or if the system
supply, SYSVDD, drops as described in Section 17.7.1.
The fast charge mode comprises two phases, as described in Section 17.7.1. When the charger is in
the constant voltage charge phase, the CHG_TOPOFF bit will be set to indicate that the charge is
approaching completion.
When the battery reaches the target voltage, the charger enters the constant voltage charge phase,
in which the WM8311 regulates BATTVDD to the target voltage. When the charger is in the constant
voltage charge phase, then the CHG_TOPOFF bit will be set (see Section 17.7.2) to indicate that the
charge is approaching completion.
The register control fields for fast charging are described in Table 59. Note that the Battery Charger
control registers are locked by the WM8311 User Key. These registers can only be changed by
writing the appropriate code to the Security register, as described in Section 12.4.
Table 59 Fast Charge Control
R16456
(4048h)
Charger
Control 1
R16457
(4049h)
Charger
Control 2
ADDRESS
BIT
3:0
15
CHG_FAST
CHG_FAST_ILIM
[3:0]
LABEL
DEFAULT
0010
0
Battery Fast Charge Enable
0 = Disable
1 = Enable
Protected by user key
Battery Fast Charge current limit
0000 = 0mA
0001 = 50mA
0010 = 100mA
0011 = 150mA
0100 = 200mA
0101 = 250mA
0110 = 300mA
0111 = 350mA
1000 = 400mA
1001 = 450mA
1010 = 500mA
1011 = 600mA
1100 = 700mA
1101 = 800mA
1110 = 900mA
1111 = 1000mA
Protected by user key
PP, December 2009, Rev 3.0
DESCRIPTION
Pre-Production
110