Datasheet

VREF
TS
RT2
RT1
RTH
103AT
bq24600
o
o o
1
f =
2 L Cp
bq24600
SLUS891A –FEBRUARY 2010– REVISED OCTOBER 2011 www.ti.com
Figure 15. TS Resistor Network
Timer Fault Recovery
The bq24600 provides a recovery method to deal with timer fault conditions. The following summarizes this
method:
Condition 1: The battery voltage is above the recharge threshold and a timeout fault occurs.
Recovery Method: The timer fault clears when the battery voltage falls below the recharge threshold, and
battery detection begins. Taking CE low or a POR condition also clears the fault.
Condition 2: The battery voltage is below the recharge threshold and a timeout fault occurs.
Recovery Method: Under this scenario, the bq24600 applies the I
FAULT
current to the battery. This small current
is used to detect a battery removal condition and remains on as long as the battery voltage stays below the
recharge threshold. If the battery voltage goes above the recharge threshold, the bq24600 disables the fault
current and executes the recovery method described in Condition 1. Taking CE low or a POR condition also
clears the fault.
PG Output
The open-drain PG (power-good) output indicates whether the VCC voltage is valid or not. The open-drain FET
turns on whenever bq24600 has a valid VCC input (not in UVLO or ACOV or SLEEP mode). The PG pin can be
used to drive an LED or communicate to the host processor. It can also be used to drive ACFET and BATFET.
CE (Charge Enable)
The CE digital input is used to disable or enable the charge process. A high-level signal on this pin enables
charge, provided all the other conditions for charge are met (see Enabling and Disabling Charge). A high-to-low
transition on this pin also resets all timers and fault conditions. There is an internal 1-MΩ pulldown resistor on the
CE pin, so if CE is floated the charge does not turn on.
Inductor, Capacitor, and Sense Resistor Selection Guidelines
The bq24600 provides internal loop compensation. With this scheme, best stability occurs when the LC resonant
frequency, f
o
, is approximately 17 kHz–25 kHz for the bq24600, per Equation 8:
(8)
Table 2 provides a summary of typical LC components for various charge currents.
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