BQ24165_14 Datasheet, PDF (16/38 Pages) Texas Instruments – 2.5A, Dual-Input, Single Cell Switch Mode Li-Ion Battery Charger with Power Path Management

bq24165
bq24166
bq24167
SLUSAP4B – DECEMBER 2011 – REVISED MARCH 2013
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BATTERY DETECTION
When termination conditions are met, a battery detection cycle is started. During battery detection, I_DETECT is
pulled from VBAT for t_DETECT to verify there is a battery. If the battery voltage remains above V_DETECT for the full
duration of t_DETECT, a battery is determined to present and the IC enters “Charge Done”. If VBAT falls below
V_DETECT, battery detection continues. The next cycle of battery detection, the bq2416x turns on I_BATSHORT for
t_DETECT. If VBAT rises to V_DETECT, the current source is turned offand after t_DETECT, the battery detection continues
through another current sink cycle. Battery detection continues until charge is disabled or a battery is detected.
Once a battery is detected, the fault status clears and a new charge cycle begins. Figures 6 and 7 show the
oscillation on VBAT prior to battery insertion and after battery removal. Battery detection is disabled when
termination is disabled.
DYNAMIC POWER PATH MANAGEMENT
The bq24165/6/7 features a SYS output that powers the external system load connected to the battery. This
output is active whenever a source is connected to IN, USB or BAT. The following sections discuss the behavior
of SYS with a source connected to the supply (IN or USB) or a battery source only.
INPUT SOURCE CONNECTED
When a source is connected to IN or USB, and the bq24165/6/7 is enabled, the buck converter starts up. If
charging is enabled using CE1 and CE2(bq24165) or CE (bq24166/7), the charge cycle is initiated. When V_BAT >
3.5V, the internal battery FET is turned on and the SYS output is connected to V_BAT. If the SYS voltage falls to
V_SYS(REG), it is regulated to that point to maintain the system output even with a deeply discharged or absent
battery. In this mode, the SYS output voltage is regulated by the buck converter and the battery FET is linearly
regulated to regulate the charge current into the battery. The current from the supply is shared between charging
the battery and powering the system load at SYS. The dynamic power path management (DPPM) circuitry of the
bq24165/6/7 monitors the SYS voltage continuously. If V_SYS falls to V_MINSYS, the DPPM circuit adjusts charge
current to maintain the load on SYS while preventing the system voltage from crashing. If the charge current is
reduced to zero and the load increases further, the bq24165/6/7 enters battery supplement mode. During
supplement mode, the battery FET is turned on and the battery supplements the system load. When the charge
current is reduced by the DPPM regulation loop, the safety timer runs at half speed, so that it is twice a long.
This prevents false safety timer faults. See the Safety Timer section for more details.
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