BQ24030-Q1 Datasheet, PDF (15/34 Pages) Texas Instruments – SINGLE-CHIP CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC

bq24030-Q1
bq24031-Q1
www.ti.com.................................................................................................................................................... SLUS793B – APRIL 2008 – REVISED OCTOBER 2009
Under USB operation, when the loads exceeds the programmed input current thresholds a similar pattern is
observed. If the output load exceeds the available USB current, the output instantly goes into the battery
supplement mode.
V_AC
V_OUT
V_OUT Regulated at 4.4 V
V_{DPPM - OUT} = 4.26 V, DPPM Mode
V_OUT ≈ V_BAT, BAT Supplement Mode
I_CHG
I_OUT
Figure 5. DPPM and Battery Supplement Modes
Figure 6 illustrates when PSEL is toggled low for 500 μs. Power transfers from AC to USB to AC [channel 1
(CH1) VAC = 5.4 V, channel 2 (CH2) V_(USB) = 5 V, channel 3 (CH3) V_OUT, output current I_OUT = 0.25 A, channel 4
(CH4) V_BAT = 3.5 V, and I_(PGM-CHG) = 1 A]. When the PSEL goes low (first division), the AC FET opens, and the
output falls until the USB FET turns on. Turning off the active source before turning on the replacement source is
referred to as break-before-make switching. The rate of discharge on the output is a function of system
capacitance and load. Note the cable IR drop in the AC and USB inputs when they are under load. At the fourth
division, the output has reached steady-state operation at V_(DPPM-REG) (charge current has been reduced due to
the limited USB input current). At the sixth division, the PSEL goes high and the USB FET turns off followed by
the AC FET turning on. The output returns to its regulated value, and the battery returns to its programmed
current level.
Break Before Make
System Capacitance
Powering System
DPPM Mode
USB is Charging System Capacitance
V_AC
V_USB
V_OUT
V_BAT
Hi
PSEL
Low
Figure 6. Toggle PSEL Low
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