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| BQ24030_07 Datasheet, PDF (17/38 Pages) Texas Instruments – SINGLE-CHIP CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC (bqTINY) | |||
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bq24030, bq24031, bq24032A
bq24035, bq24038
SLUS618F â AUGUST 2004 â REVISED NOVEMBER 2006
Break Before Make
System Capacitance
Powering System
DPPM Mode
USB is Charging System Capacitance
VAC
VUSB
VOUT
VBAT
Hi
PSEL
Low
Figure 6. Toggle PSEL Low
Figure 7 illustrates when AC is removed, power transfers to USB; PSEL = H (AC primary source); channel 1
(CH1) VAC = 5.4 V; channel 2 (CH2) V(USB) = 5 V; channel 3 (CH3) VOUT; output current, IOUT = 0.25 A; channel
4 (CH4) VBAT = 3.5 V; and I(PGM-CHG) = 1 A. The power transfer from AC to USB only takes place after the
primary source (AC) is considered bad (too low, VAC<=VBAT + 125 mV) indicated by the ACPG FET turning off
(open drain not shown). Thus, the output drops down to the battery voltage before the USB source is connected
(6th div). The output starts to recover when the USB FET starts to limit the input current (7th div) and the output
drops to the V(DPPM-REG) threshold.
USB Input Current Limit is Reached.
DPPM Mode
VUSB
VOUT
VAC
VBAT
AC Declared Not Present, USB Power Applied
Figure 7. Remove AC â PWR XFER to USB
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