Datasheet

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Sleep Mode
Overvoltage Lockout
Stand-By Mode
Begin Charge Mode
Charging Mode
Suspend Mode
LDO Mode Operation
bq2406x
SLUS689A – JUNE 2006 – REVISED OCTOBER 2006
The bq2406x enters the sleep mode when the input power voltage (IN) is above the power down threshold
V(PDWN) but still lower than the input power detection threshold, V(IN) < V(OUT) + V
IN(DT)
.
During the sleep mode the charger is off, and the host commands at the control pins are not interpreted. The
integrated power mosfet connected between IN and OUT pins is off, the status output pins STAT1 and STAT2
are set to the high impedance state and the PG output indicates input power not detected.
The sleep mode is entered from any other state, if the input power (IN) is not detected.
The input power is detected when the input voltage V(IN) > V(OUT) + V
IN(DT)
. When the input power is detected
the bq2460x transitions from the sleep mode to the power-on-reset mode. In this mode of operation an internal
timer T
(POR)
is started and internal blocks are reset (power-on-reset). Until the timer expires the STAT1 and
STAT2 outputs indicate charger OFF, and the PG output indicates the input power status as not detected.
At the end of the power-on-reset delay the internal comparators are enabled, and the STAT1, STAT2 and PG
pins are active.
In the bq24061/63 the stand-by mode is started at the end of the power-on-reset phase, if the input power is
detected and CE = HI. In the stand-by mode selected blocks in the IC are operational, and the control logic
monitors system status and control pins to define if the charger will set to on or off mode. The quiescent current
required in stand-by mode is 100 µ A typical.
If the CE pin is not available the bq2406x enters the begin charge mode at the end of the power-on-reset phase.
All blocks in the IC are powered up, and the bq2406x is ready to start charging the battery pack. A new charge
cycle is started when the control logic decides that all conditions required to enable a new charge cycle are met.
During the begin charge phase all timers are reset, after that the IC enters the charging mode.
When the charging mode is active the bq2406x executes the charging algorithm, as described in the operational
flow chart, Figure 17 .
The suspend mode is entered when the pack temperature is not within the valid temperature range. During the
suspend mode the charger is set to off, but the timers are not reset.
The normal charging mode resumes when the pack temperature is within range.
The LDO Mode (TMR pin open circuit) disables the charging termination circuit, disables the battery detect
routine and holds the safety timer clock in reset. This is often used for operation without a battery or in
production testing. This mode is different than a typical LDO since it has different modes of operation, and
delivers less current at lower output voltages. See Figure 24 for the output current versus the output voltage.
Note that a load on the output prior to powering the device may keep the part in short-circuit mode. Also, during
normal operation, exceeding the programmed fast charge level causes the output to drop, further restricting the
output power, and soon ends up in short-circuit mode. Operation with a battery or keeping the average load
current below the programmed current level prevents this type of latch up. The out pin current can be monitored
via the ISET pin. If in LDO mode without a battery present, It is recommended that a 200- Ω feedback resistor,
R8, be used, see Figure 16 .
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