CSR BlueCore CSR8640 BGA, User Manual

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Figure 11.1 shows the mode-to-mode transition voltages. These voltages are fixed and calibrated by CSR, see
Section 11.2. The transition between modes can occur at any time.
G
-T
W
-0
005583.3.2
Battery Voltage
C
har
ge
Cu
rr
en
t
V
fast
I
fast
I
term V
hyst
I
trickle
V
float
Trickle Charge Mode
Fast Charge Mode
Constant Current
Fast Charge Mode
Constant Voltage
Standby Mode
Figure 11.1: Battery Charger Mode-to-Mode Transition Diagram
11.1.1 Disabled Mode
In the disabled mode the battery charger is fully disabled and draws no active current on any of its terminals.
11.1.2 Trickle Charge Mode
In the trickle charge mode, when the voltage on VBAT_SENSE is lower than the V
fast
threshold, a current of
approximately 10% of the fast charge current, I
fast
, is sourced from the VBAT pin.
The V
fast
threshold detection has hysteresis to prevent the charger from oscillating between modes.
11.1.3 Fast Charge Mode
When the voltage on VBAT_SENSE is greater than V
fast
, the current sourced from the VBAT pin increases to I
fast
.
I
fast
is between 10mA and 200mA set by PS Key or a VM trap. In addition, I
fast
is calibrated in production test to
correct for process variation in the charger circuit.
The current is held constant at I
fast
until the voltage at VBAT_SENSE reaches V
float
, then the charger reduces the
current sourced to maintain a constant voltage on the VBAT_SENSE pin.
When the current sourced is below the termination current, I
term
, the charging stops and the charger enters standby
mode. I
term
is typically 10% of the fast charge current.
11.1.4 Standby Mode
When the battery is fully charged, the charger enters standby mode, and battery charging stops. The battery voltage
on the VBAT_SENSE pin is monitored, and when it drops below a threshold set at V
hyst
below the final charging
voltage, V
float
, the charger re-enters fast charge mode.
11.1.5 Error Mode
The charger enters the error mode if the voltage on the VCHG pin is too low to operate the charger correctly
(VBAT_SENSE is greater than VCHG - 50mV (typical)).
Advance Information
This material is subject to CSR's non-disclosure agreement
© Cambridge Silicon Radio Limited 2011
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CSR8640 BGA
Data Sheet