BQ24090 Datasheet, PDF (19/31 Pages) Texas Instruments – 1A, Single-Input, Single Cell Li-Ion Battery Charger

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bq24090, bq24091
bq24092, bq24093
SLUS968A – JANUARY 2010 – REVISED FEBRUARY 2010
ISET
An external resistor is used to Program the Output Current (50 to 800mA) and can be used as a current monitor.
R_ISET = K_ISET ÷ I_OUT
(1)
(1)
Where:
I_OUT is the desired fast charge current;
K_ISET is a gain factor found in the electrical specification
For greater accuracy at lower currents, part of the sense FET is disabled to give better resolution. Figure 15
shows the transition from low current to higher current. Going from higher currents to low currents, there is
hysteresis and the transition occurs around 0.15A.
The ISET resistor is short protected and will detect a resistance lower than Ⅹ340Ω. The detection requires at
least 80mA of output current. If a “short” is detected, then the IC will latch off and can only be reset by cycling the
power. The OUT current is internally clamped to a maximum current between 1.1A and 1.35A and is independent
of the ISET short detection circuitry, as shown in Figure 23. Also, see Figure 9 and Figure 10.
4.5
For < 45^oC, 4.2V Regulation
4
3.5
60^oC to 45^oC
HOT TEMP
3
4.06V
Regulation
2.5
V_OUT
2
No Operation
During Cold
Fault
< 48^oC
1.5
60^oC
10^oC
0^oC
100% of Programmed
1
Current
0.5
I_OUT
0
0
0.2
0.4
0.6
0.8
50%
Cold
Fault
1
1.2
1.4
1.6
1.8
V_TS - Voltage - V
Figure 22. Operation Over TS Bias Voltage
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