Datasheet

VR EF
LTF
CO LD
V
1
V
RT1 =
1 1
+
RT2 RTH
-
VREF
TS
RT2
RT1
RTH
103AT
bq24650
bq24650
www.ti.com SLUSA75 –JULY 2010
(8)
Figure 18. TS Resistor Network
CHARGE ENABLE
MPPSET is used to disable or enable the charge process. A voltage above 175mV on this pin enables charge,
provided all other conditions for charge are met (see the Enabling and Disabling Charge section). A voltage
below 75mV on this pin also resets all timers and fault conditions.
INDUCTOR, CAPACITOR, AND SENSE RESISTOR SELECTION GUIDELINES
The bq24650 provides internal loop compensation. With this scheme, the best stability occurs when the LC
resonant frequency, f
o
, is approximately 12kHz – 17kHz for the bq24650.
Table 1 provides a summary of typical LC components for various charge currents.
Table 1. Typical Inductor, Capacitor, and Sense Resistor Values as a Function of Charge Current
CHARGE CURRENT 0.5A 1A 2A 4A 8A 10A
Output inductor low 22 µH 15 µH 10 µH 6.8 µH 3.3 µH 3.3 µH
Output capacitor C
O
7 µF 10 µF 15 µF 20 µF 40 µF 40 µF
Sense resistor 80 mΩ 40 mΩ 20 mΩ 10 mΩ 5 mΩ 4 mΩ
CHARGE STATUS OUTPUTS
The open-drain STAT1 and STAT2 outputs indicate various charger operations as listed in Table 2. 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 2. STAT Pin Definition for bq24650
CHARGE STATE STAT1 STAT2
Charge in progress ON OFF
Charge complete OFF ON
Charge suspend, over-voltage, sleep mode, battery absent OFF OFF
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