Datasheet

bq24610
bq24617
www.ti.com SLUS892B –DECEMBER 2009–REVISED SEPTEMBER 2013
For example, 103AT NTC thermistors are used to monitor the battery pack temperature. Select T
COLD
= 0ºC and
T
CUT_OFF
= 45ºC; then we get R
T2
= 430 kΩ, R
T1
= 9.31 kΩ. A small RC filter is suggested to use for system-level
ESD protection.
Timer Fault Recovery
The bq24610/7 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 will begin. 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 bq24610/7 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 bq24610/7 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 bq24610/7 has a valid VCC input (not in UVLO or ACOV or SLEEP mode). The PGpin can be
used to drive an LED or communicate to the host processor.
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 bq24610/7 provides internal loop compensation. With this scheme, best stability occurs when the LC
resonant frequency, f
o
, is approximately 12 kHz to 17 kHz for bq24610/7.
The following table provides a summary of typical LC components for various charge currents:
Table 2. Typical Inductor, Capacitor, and Sense Resistor Values as a Function of Charge Current for
bq24610/7 (600 kHz Switching Frequency)
CHARGE CURRENT 2A 4A 6A 8A 10A
Output inductor L
O
6.8 μH 6.8 μH 4.7 μH 3.3 μH 3.3 μH
Output capacitor C
O
20 μF 20 μF 30 μF 40 μF 40 μF
Sense resistor 10 mΩ 10 mΩ 10 mΩ 10 mΩ 10 mΩ
Charge Status Outputs
The open-drain STAT1 and STAT2 outputs indicate various charger operations as shown in the Table 3. These
status pins can be used to drive LEDs or communicate with the host processor. Note that OFF indicates that the
open-drain transistor is turned off.
Table 3. STAT Pin Definition for bq24610/7
CHARGE STATE STAT1 STAT2
Charge in progress ON OFF
Charge complete OFF ON
Charge suspend, timer fault, overvoltage, sleep mode, battery absent OFF OFF
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