Datasheet

o
o o
1
f =
2 L Cp
bq24620
SLUS893A –MARCH 2010– REVISED OCTOBER 2011 www.ti.com
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 Enable and Disable Charging, ENABLE AND
DISABLE CHARGING). 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 floatedthe charge does not turn on.
INDUCTOR, CAPACITOR, AND SENSE-RESISTOR SELECTION GUIDELINES
The bq24620 provides internal loop compensation. With this scheme, best stability occurs when the LC resonant
frequency, f
o
, is approximately 10kHz – 15kHz per Equation 7:
(7)
Table 2 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
CHARGE CURRENT 2 A 4 A 6 A 8 A 10 A
Output inductor L
O
8.2 μH 8.2 μH 5.6 μH 4.7 μH 4.7 μH
Output capacitor C
O
20 μF 20 μF 20 μF 40 μF 40 μF
Sense resistor 10 mΩ 10 mΩ 10 mΩ 10 mΩ 10 mΩ
CHARGE STATUS OUTPUTS
The open-drain STAT outputs indicate various charger operations as shown in 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 bq24620
CHARGE STATE STAT
Charge in progress ON
Charge complete (PG = LOW) OFF
Sleep mode (PG = HIGH) OFF
Charge suspend, timer fault, ACOV, battery absent BLINK (0.5 Hz)
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