BQ27620-G1 Datasheet, PDF (35/45 Pages) Texas Instruments – System-Side Impedance Track™ Fuel Gauge

bq27620-G1
www.ti.com
SLUSAE3 – OCTOBER 2012
The charging should not start when the temperature is below the Charge Inhibit Temp Low or above the
Charge Inhibit Temp High. The charging can continue if the charging starts inside the window [Charge
Inhibit Temp Low, Charge Inhibit Temp High] until the temperature is either below Suspend Low Temp or
above the Suspend Low Temp. Therefore, the window [Charge Inhibit Temp Low, Charge Inhibit Temp
High] must be inside the window of [Suspend Low Temp, Suspend High Temp].
5.7 POWER MODES
The bq27620-G1 has different power modes: BAT INSERT CHECK, NORMAL and HIBERNATE. In
NORMAL mode, the bq27620-G1 is fully powered and can execute any allowable task. In HIBERNATE
mode, the fuel gauge is in a low power state, but can be woken up by communication or certain I/O
activity. Finally, the BAT INSERT CHECK mode is a powered-up, but low-power halted, state, where the
bq27620-G1 resides when no battery is inserted into the system.
The relationship between these modes is shown in Figure 5-1.
5.7.1 BAT INSERT CHECK Mode
This mode is a halted-CPU state that occurs when an adapter, or other power source, is present to power
the bq27620-G1 (and system), yet no battery has been detected. When battery insertion is detected, a
series of initialization activities begin, which include: OCV measurement, setting the BAT_GD pin, and
selecting the appropriate battery profiles.
Some commands, issued by a system processor, can be processed while the bq27620-G1 is halted in this
mode. The gauge will wake up to process the command, then return to the halted state awaiting battery
insertion.
5.7.2 NORMAL MODE
The fuel gauge is in NORMAL mode when not in any other power mode. During this mode,
EffectiveCurrent( ), Voltage( ) and Temperature( ) measurements are taken, and the interface data set is
updated. Decisions to change states are also made. This mode is exited by activating a different power
mode.
Because the gauge consumes the most power in NORMAL mode, the Impedance Track™ algorithm
minimizes the time the fuel gauge remains in this mode.
5.7.3 HIBERNATE MODE
HIBERNATE mode should be used when the system equipment needs to enter a low-power state, and
minimal gauge power consumption is required. This mode is ideal when a system equipment is set to its
own HIBERNATE, SHUTDOWN, or OFF modes.
Before the fuel gauge can enter HIBERNATE mode, the system must set the [HIBERNATE] bit of the
CONTROL_STATUS register. The gauge waits to enter HIBERNATE mode until it has taken a valid OCV
measurement and the magnitude of the average cell current has fallen below Hibernate Current. The
gauge can also enter HIBERNATE mode if the cell voltage falls below Hibernate Voltage. The gauge will
remain in HIBERNATE mode until the system issues a direct I²C command to the gauge or a POR occurs.
I²C Communication that is not directed to the gauge will not wake the gauge.
It is important that BAT_GD be de-asserted status (no battery charging/discharging). This prevents a
charger application from inadvertently charging the battery before an OCV reading can be taken. It is the
system’s responsibility to wake the bq27620-G1 after it has gone into HIBERNATE mode. After waking,
the gauge can proceed with the initialization of the battery information (OCV, profile selection, etc.)
Copyright © 2012, Texas Instruments Incorporated
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FUNCTIONAL DESCRIPTION
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