BQ24266_15 Datasheet, PDF (17/41 Pages) Texas Instruments – bq24266 3A, 30V Standalone Single-Input, Single-Cell Switchmode Li-Ion Battery Charger

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Device Functional Modes (continued)
RTOP = 10kW ´ ^VIN_DPM-VDPM
VDPM
.
bq24266
SLUSBY5F – JUNE 2014 – REVISED AUGUST 2015
(1)
V_IN
(5V Offset)
Input voltage regulated to VIN_DPM
1V/div
I_IN
V_SYS
(3.6V Offset)
I_BAT
Normal Charging (1A)
I_SYS
Input current limit reduced to avoid crashing adapter
SYS enters supplement mode to ensure SYS load is supported
800us/div
Figure 9. bq24266 V_IN-DPM
2A/div
500mV/div
2A/div SYS load removed,
normal charging
resumes
2A/div
7.4.3.1.3 Input Overvoltage Protection
The built-in input overvoltage protection protects the bq24266 and downstream components connected to SYS
and/or BAT against damage from overvoltage on the input supply (Voltage from V_IN to PGND). When V_IN > V_OVP,
the bq24266 turns off the PWM converter immediately. After the deglitch time t_{DGL(BUCK_OVP)}, an OVP fault is
determined to exist. During the OVP fault the bq24266 turns the battery FET and BGATE on. Once the OVP fault
is removed, the device returns to normal operation.
The OVP threshold is 14V for operation from standard adapters and from 12V sources.
7.4.3.2 Charge Profile
When a valid input source is connected (V_IN>V_UVLO and V_BAT+V_SLP<V_IN<V_OVP), charging is enabled.
The charge current, I_CHARGE, is set using the ISET pin by connecting a resistor form ISET to GND. The current is
programmable from 500mA to 3A using Equation 2, where I_CHARGE is in Amperes, and K_ISET is the value specified
in the Electrical Characteristics table.
R_CHARGE
=
K_ISET
R_ISET
(2)
The bq24266 supports a precision Li-Ion or Li-Polymer charging system for single-cell applications. Charging is
done through the internal battery MOSFET. There are 6 loops that influence the charge current; constant current
loop (CC), constant voltage loop (CV), thermal regulation loop, minimum system voltage loop (MINSYS), input
current limit and V_IN-DPM. During the charging process, all six loops are enabled and the one that is dominant
takes control. The minimum system output feature regulates the system voltage to V_SYSREG(LO), so that startup is
enabled even for a missing or deeply discharged battery. Figure 10 shows a typical charge profile including the
minimum system output voltage feature.
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