Datasheet

PRE
CHARGE
CC FAST
CHARGE
CV
TAPER
DONE
Battery
Voltage
Battery
Current
Termination
I
TERM
V
LOWV
V
OREG
ICHRG[1:0]
I
PRECHG
PRE
CHARGE
CC FAST
CHARGE
CV
TAPER
DONE
Battery
Voltage
Battery
Current
Termination
I
TERM
V
LOWV
V
OREG
ICHRG[1:0]
I
PRECHG
Thermal
Regulation
T
J(REG)
IC junction teperature T
J
TPS65217A, TPS65217B, TPS65217C, TPS65217D
SLVSB64F –NOVEMBER 2011–REVISED APRIL 2013 www.ti.com
AC and USB Input Discharge
AC and USB inputs have 90-µA internal current sinks which are used to discharge the input pins to avoid false
detection of an input source. The AC sink is enabled when USB is a valid supply and V
AC
is below the detection
threshold. Likewise, the USB sink is enabled when AC is a valid supply and V
USB
is below the detection limit.
Both current sinks can be forced OFF by setting the [ACSINK, USBSINK] bits to 11b. Both bits are located in
register 0x01 (PPATH).
NOTE
[ACSINK, USBSINK] = 01b and 10b combinations are not recommended as these may
lead to unexpected enabling and disabling of the current sinks.
BATTERY CHARGING
When the charger is enabled (CH_EN bit set to 1) it first checks for a short-circuit on the BAT pin by sourcing a
small current and monitoring the BAT voltage. If the voltage on the BAT pin rises above V
BAT(SC)
, a battery is
present and charging can begin. The battery is charged in three phases: pre-charge, constant current fast charge
(current regulation) and a constant voltage charge (voltage regulation). In all charge phases, an internal control
loop monitors the IC junction temperature and reduces the charge current if an internal temperature threshold is
exceeded. Figure 10 shows a typical charging profile.
Figure 10. LEFT: Typical charge current profile with termination enabled. RIGHT: Modified charging
profile with thermal regulation loop active and termination enabled.
In the pre-charge phase, the battery is charged at a current of IPRECHG which is typically 10% of the fast-
charge current rate. The battery voltage starts rising. Once the battery voltage crosses the V
LOWV
threshold, the
battery is charged at a current of I
CHG
. The battery voltage continues to rise. When the battery voltage reaches
V
OREG
, the battery is held at a constant value of V
OREG
. The battery current now decreases as the battery
approaches full charge. When the battery current reaches I
TERM
, the TERMI flag in register CHGCONFIG0 is set
to 1. To avoid false termination when the DPM or thermal loop kicks in, termination is disabled when either loop
is active.
The charge current cannot exceed the input current limit of the power path minus the load current on the SYS pin
because the power-path manager will reduce the charge current to support the system load if the input current
limit is exceeded. Whenever the nominal charge current is reduced by action of the power path manger, the DPM
loop, or the thermal loop the safety timer is clocked with half the nominal frequency to extend the charging time
by a factor of 2.
Precharge
The pre-charge current is pre-set to a factor of 10% of the fast-charge current ICHRG[1:0] and cannot be
changed by the user.
26 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated
Product Folder Links: TPS65217A TPS65217B TPS65217C TPS65217D