Texas Instruments BQ25120F3A, Manual

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9.3.10 Battery Supplement Mode
While in DPPM mode, if the charging current falls to zero and the system load current increases beyond the
programmed input current limit, the voltage at PMID reduces further. When the PMID voltage drops below the
battery voltage by V
(BSUP1)
, the battery supplements the system load. The battery stops supplementing the
system load when the voltage on the PMID pin rises above the battery voltage by V
(BSUP2)
. During supplement
mode, the battery supplement current is not regulated, however, the short-circuit protection circuit is active.
Battery termination is disabled while in supplement mode.
9.3.11 Default Mode
The default mode is used when there is no host, or I
2
C communication is not available. If the externally
programmable pins, ILIM, ISET, and ITERM have resistors connected, that is considered the default mode. If any
one of these resistors is tied to GND, the default register settings are used. The default mode can be entered by
connecting a valid power source to V
IN
or the RESET bit is written. Default mode is exited by writing to the I
2
C
interface.
9.3.12 Termination and Pre-Charge Current Programming by External Components (IPRETERM)
The termination current threshold is user programmable through an external resistor or through registers over
I
2
C. Set the termination current using the IPRETERM pin by connecting a resistor from IPRETERM to GND. The
termination can be set between 5% and 20% of the programmed output current set by ISET, using Table 9-3 for
guidance:
Table 9-3. IPRETERM Resistor Settings
IPRE_CHARGE and ITERM KKIPRETERM
RIPRETERM
(STANDARD 1%
VALUES)
UNIT
MIN
TYP
(% of ISET)
MAX MIN TYP MAX
RECOMMENDED
RIPRETERM
5 180 200 220 15000 Ω
10 180 200 220 4990 Ω
15 180 200 220 1650 Ω
20 180 200 220 549 Ω
Using the I
2
C register, the termination current can be programmed with a minimum of 500 µA and a maximum of
37 mA.
The pre-charge current is not independently programmable through the external resistor, and is set at the
termination current. The pre-charge and termination currents are programmable using the IPRETERM registers.
If no IPRETERM resistor is connected and the pin is tied to GND, the default values in the IPRETERM registers
are used. The external value can be used in host mode by configuring the IPRETERM registers. If the external
ICHG setting will be used after being in Host mode, the IPRETERM registers should be set to match the desired
external threshold for the highest ICHG accuracy.
Termination is disabled when any loop other than CV is active.
BQ25120F3A
SLUSDI4A – OCTOBER 2018 – REVISED APRIL 2021
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