BQ24262_15 Datasheet, PDF (21/56 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
www.ti.com
bq24260, bq24261, bq24261M, bq24262
SLUSBU4D – DECEMBER 2013 – REVISED APRIL 2015
Device Functional Modes (continued)
9.4.9 Battery Discharge FET (BGATE)
The bq24260/1/1M/2 contains a MOSFET driver to drive an external discharge FET between the battery and the
system output. This external FET provides a low impedance path for supplying the system from the battery.
Connect BGATE to the gate of the external discharge P-channel MOSFET. BGATE is on (low) under the
following conditions:
1. No input supply connected.
2. HZ_MODE = 1
3. CD terminal = 1
9.4.10 DEFAULT Mode
DEFAULT mode is used when I²C communication is not available. DEFAULT mode is entered in the following
situations:
1. When the charger is enabled and V_BAT<V_BATGD before I²C communication is established
2. When the watchdog timer expires without a reset from the I²C interface
3. The RESET bit is written in the I²C register
In DEFAULT mode, the I²C registers are reset to the default values. The 2-minute safety timer is reset and starts
when DEFAULT mode is entered if a charge cycle is underway. The default value for V_BATREG is 3.6 V for the
bq24260/1/1M and 4.2 V for the bq24262. The default value for I_CHARGE is 1 A. For the bq24260, the input current
limit is determined by the D+/D– detection (See D+/D– Based Adapter Detection section). For the bq24261,
bq24261M and bq24262, the input current limit in DEFAULT mode is set by PSEL. (See Power Source Selector
Input section) DEFAULT mode is exited by writing to the I²C interface. Note that if termination is enabled and
charging has terminated, a new charge cycle is NOT initiated when entering DEFAULT mode.
9.4.11 Good Battery Monitor
The bq2426x contains a good battery monitor circuit that places the bq2426x into hi-z mode if the battery voltage
is above the V_BATGD threshold while in DEFAULT mode. This function is used to enable compliance to the
battery charging standard that prevents charging from an un-enumerated USB host while the battery is above the
good battery threshold. If the bq24260/1/1M/2 is in HOST mode, it is assumed that USB host has been
enumerated and the good battery circuit has no effect on charging. Any write to the I²C places the
bq24260/1/1M/2 in HOST mode and clears the high-impedance mode condition. The HZ_MODE bit is not
updated during this condition.
9.4.12 D+/D– Based Adapter Detection (D+/D–, bq24260 only)
The bq24260 contains a D+/D- based adapter detection circuit that is used to program the input current limit for
the input during DEFAULT mode. D+/D- is only performed in DEFAULT mode unless forced by the D+/D-_EN
bit in host mode.
By default the input current limit is set to 100 mA. During DEFAULT mode, when the input source is connected,
the bq24260 performs an adapter detection to determine if it is connected to a USB port or dedicated charger.
The adapter detection starts with a connection detection as described in the USB Battery Charging Specification
ver 1.2 (BC1.2). Once a connection is detected, the adapter detection is performed. If a connection is not
detected within 500ms, the adapter detection begins. The adapter detection runs as described in BC1.2. If a
CDP/DCP is detected, the input current limit is increased to 1.5 A. If an SDP is detected, the current limit
remains at 100 mA, until changed in the I²C.
D+/D- is initiated at any time by the host by setting the D+/D- EN bit in the I²C to 1. After detection is complete
the D+/D- EN bit is automatically reset to 0 and the detection circuitry is disconnected from the D+ D- terminals
to avoid interference with USB data transfer. When a command is written to change the input current limit in the
I²C, this overrides the current limit selected by D+/D- detection.
Copyright © 2013–2015, Texas Instruments Incorporated
Submit Documentation Feedback
21
Product Folder Links: bq24260 bq24261 bq24261M bq24262