BQ24090_12 Datasheet, PDF (19/34 Pages) Texas Instruments – 1A, Single-Input, Single Cell Li-Ion and Li-Pol Battery Charger

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SLUS968D – JANUARY 2010 – REVISED DECEMBER 2012
1.8
1.6
1.4
1.2
I_OUT Internal Clamp Range
1
0.8
max
0.6
I_SET Short
0.4
Fault
Range
0.2
min
0
100
I_OUT Programmed
Non Restricted
Operating Area
1000
I_SET - W
Figure 22. Programmed/Clamped Out Current
10000
PRE_TERM – Pre-Charge and Termination Programmable Threshold
Pre-Term is used to program both the pre-charge current and the termination current threshold. The pre-charge
current level is a factor of two higher than the termination current level. The termination can be set between 5%
and 50% of the programmed output current level set by ISET. If left floating the termination and pre-charge are
set internally at 10/20% respectively. The pre-charge-to-fast-charge, V_lowv threshold is set to 2.5V.
R_PRE-TERM = %Term × K_TERM = %Pre-CHG × K_PRE-CHG
(2)
(2)
Where:
%Term is the percent of fast charge current where termination occurs;
%Pre-CHG is the percent of fast charge current that is desired during precharge;
K_TERM and K_PRE-CHG are gain factors found in the electrical specifications.
ISET2
Is a 3-state input and programs the Input Current Limit/Regulation Threshold. A low will program a regulated fast
charge current via the ISET resistor and is the maximum allowed input/output current for any ISET2 setting, Float
will program a 100mA Current limit and High will program a 500mA Current limit.
Below are two configurations for driving the 3-state ISET2 pin:
V_CC
To
ISET2
Drive
Logic
V_CC
R1
To ISET2
OR
Q1
R2
Drive
Logic
R1 Divider
set to 0.9 V
Which is the
Float Voltage
Q2
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