BQ25120_16 Datasheet, PDF (21/68 Pages) Texas Instruments – Highly Integrated Battery Charge Management Solution

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BQ25120, BQ25121
SLUSBZ9B – AUGUST 2015 – REVISED MAY 2016
9.3.9 Dynamic Power Path Management Mode
With a valid input source connected, the power-path management circuitry monitors the input voltage and current
continuously. The current into IN is shared at PMID between charging the battery and powering the system load
at PMID, SYS, and LS/LDO. If the sum of the charging and load currents exceeds the preset maximum input
current, the input DPM loop reduces input current. If PMID drops below the DPPM voltage threshold, the
charging current is reduced by the DPPM loop through the BATFET. If PMID continues to drop after BATFET
charging current is reduced to zero, the part enters supplement mode when PMID falls below the supplement
mode threshold. Battery termination is disabled while in DPPM mode.
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 I²C communication is not available. If the externally
programmable pins, ILIM, ISET, and ITERM have resistors connected, that is considered the default mode. If
they are 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 I²C 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
I²C. 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 3 for
guidance:
Table 3. IPRETERM Resistor Settings
IPRE_CHARGE and ITERM
MIN
TYP
(% of ISET)
MAX
5
10
15
20
KKIPRETERM
RIPRETERM
(STANDARD 1%
VALUES)
UNIT
MIN
TYP
MAX
RECOMMENDED
RIPRETERM
180
200
220
15000
Ω
180
200
220
4990
Ω
180
200
220
1650
Ω
180
200
220
549
Ω
Using the I²C 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 I_PRETERM registers.
If no IPRE_TERM resistor is connected and the pin is tied to GND, the default values in the I_PRETERM
registers are used. The external value can be used in host mode by configuring the I_PRETERM registers. If the
external ICHG setting will be used after being in Host mode, the I_PRETERM 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.
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