BQ24266_15 Datasheet, PDF (24/41 Pages) Texas Instruments – bq24266 3A, 30V Standalone Single-Input, Single-Cell Switchmode Li-Ion Battery Charger

bq24266
SLUSBY5F – JUNE 2014 – REVISED AUGUST 2015
www.ti.com
Table 2. PG Behavior
CHARGE STATE
V_SUPPLY < V_UVLO
V_SUPPLY < (V_{BAT +} V_SLP)
(V_{BAT +} V_SLP) < V_IN < V_OVP
V_SUPPLY > V_OVP
PG BEHAVIOR
High Impedance
High Impedance
Low
High Impedance
The CHG output indicates new charge cycles. When a new charge cycle is initiated by CE or toggling the input
power, CHG goes low and remains low until termination. After termination, CHG remains high impedance until a
new charge cycle is initiated or the battery is removed/re-inserted. CHG does not go low during recharge cycles.
Table 3 illustrates the CHG behavior under different conditions.
Connect PG and CHG to the DRV output through an LED for visual indication, or connect through a 100kΩ
pullup to the required logic rail for host indication.
Table 3. CHG Behavior
CHARGE STATE
Charge in Progress
Charge suspended by /CE or TS function
Charging Suspended by Thermal Loop
Charging Done
Recharge Cycle after Termination
Timer Fault
No Valid Supply
V_IN > V_OVP or VIN < (V_BAT + V_SLP)
No Battery Present
CHG BEHAVIOR
Low (first charge cycle)
High-Impedance (recharge cycles)
High-Impedance
7.4.16 Boost Mode Operation
When the IUSB inputs are configured in Boost Mode (IUSB3 = 0, IUSB2 = IUSB1 = 1), the device operates in
boost mode and delivers 5V to IN to supply USB OTG devices connected to the USB connector.
7.4.16.1 PWM Controller in Boost Mode
Similar to charge mode operation, in boost mode the IC switches at 1.5MHz to regulate the voltage at IN to 5V.
The voltage control loop is internally compensated to provide enough phase margin for stable operation with the
the battery from 3.3V to 4.2V up to 1A.
In boost mode, the cycle-by-cycle current limit is set to 4A to provide protection against short circuit conditions. If
the cycle-by-cycle current limit is active for 8ms, an overload condition is detected and the device exits boost
mode, and signals an over-current fault. Additionally, discharge current limit (I_LIM(DISCHG)) is active to protect the
battery from overload. Synchronous operation and burst mode are used to maximize efficiency over the full load
range.
The bq24266 will not enter boost mode unless the IN voltage is less than the UVLO. When the boost function is
enabled, the bq24266 enters a linear mode to bring IN up to the battery voltage. Once V_IN > (V_BAT – 1V), the
bq24266 begins switching and regulates IN up to 5V. If V_IN does not rise to within 1V of V_BAT within 8ms, an
over-current event is detected and boost mode is exited.
7.4.16.2 Burst Mode during Light Load
In boost mode, the IC operates using burst mode to improve light load efficiency and reduce power loss. During
boost mode, the PWM converter is turned off when the device reaches minimum duty cycle and the output
voltage rises to V_BURST(ENT) threshold. This corresponds to approximately a 75mA inductor current. The converter
then restarts when V_IN falls to V_BURST(EXT). See Figure 22 in the Typical Operating Characteristics for an example
waveform.
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