BQ24262_15 Datasheet, PDF (26/56 Pages) Texas Instruments – bq2426x 3-A, 30-V, Host-Controlled Single-Input, Single-Cell Switched-Mode Li-Ion Battery Charger With Power-Path Management and USB-OTG Support

Not Recommended for New Designs : bq24260, bq24261
bq24260, bq24261, bq24261M, bq24262
SLUSBU4D – DECEMBER 2013 – REVISED APRIL 2015
www.ti.com
Device Functional Modes (continued)
9.4.18 Charge Status Outputs (STAT, INT)
The STAT/INT output is used to indicate operation conditions for bq24260/1/1M/2. STAT/INT is pulled low during
charging when EN_STAT bit in the control register is set to 1. When charge is complete or disabled, STAT/INT is
high impedance. When a fault occurs, a 128-µs pulse (interrupt) is sent out to notify the host. The status of
STAT/INT during different operation conditions is summarized in Table 1. STAT/INT drives an LED for visual
indication or can be connected to the logic rail for host communication. The EN_STAT bit in the control register is
used to enable/disable the charge status for STAT/INT. The interrupt pulses are unaffected by EN_STAT and will
always be shown.
Table 1. STAT Terminal Summary
CHARGE STATE
Charge in progress and EN_STAT=1
Other normal conditions
Charge mode faults: Timer faults, sleep mode, VIN overvoltage, VIN < UVLO or Sleep
mode, BOVP, thermal shutdown, No Battery and Battery Temperature faults
STAT and INT BEHAVIOR
Low
High-Impedance
128-µs pulse, then High Impedance
9.4.19 Boost Mode Operation
In HOST mode, when the operation mode bit (BOOST_EN) in the control register is set to 1, bq24260/1/1M/2
operates in boost mode and delivers 5 V to IN to supply USB OTG devices connected to the USB connector.
Boost operation can start with VBAT between 3.45 V to 4.5 V, and will maintain boost output until VBAT falls to
3.3 V. IN supplies up to 1 A to power these devices. It is not recommended to operate boost mode when the
battery voltage is less than 3.3 V. Proper operation is not ensured.
9.4.19.1 Chip Disable Input During Boost Mode (CD)
The bq24260/1/1M/2 contains a CD input that is used to disable the IC and place the bq24260/1/1M/2 into high-
impedance mode. CD must be low to enter boost mode. Driving CD high during boost mode places the
bq24260/1/1M/2 into hi-z mode and resets the BOOST_EN bit in the I²C. When CD is high, the buck converter is
off, and the battery FET and BGATE are turned on. CD is internally pulled down to GND with a 100-kΩ resistor.
9.4.19.2 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 5 V.
The voltage control loop is internally compensated to provide enough phase margin for stable operation with the
full battery voltage range and up to 1 A.
In boost mode, the cycle-by-cycle current limit is set to 4 A or 2 A (depending on the I²C setting) to provide
protection against short-circuit conditions. If the cycle-by-cycle current limit is active for 8 ms, an overload
condition is detected and the device exits boost mode, and signals an overcurrent 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 bq24260/1/1M/2 will not enter boost mode unless the IN voltage is less than the UVLO. When the boost
function is enabled, the bq24260/1/1M/2 enters a linear mode to bring IN up to the battery voltage. Once V_IN >
(V_BAT – 1 V), the bq24260/1/1M/2 begins switching and regulates IN up to 5 V. If V_IN does not rise to within 1 V of
V_BAT within 8 ms, an overcurrent event is detected and boost mode is exited and a boost mode overcurrent event
is announced, the BOOST_EN bit is reset to 0 and the STAT_x and FAULT_x bits in the Status/ Control register
are updated.
9.4.19.3 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 75-mA inductor current. The
converter then restarts when V_IN falls to V_BURST(EXT). See Figure 38 in the Application Curves for an example
waveform.
26
Submit Documentation Feedback
Copyright © 2013–2015, Texas Instruments Incorporated
Product Folder Links: bq24260 bq24261 bq24261M bq24262