Datasheet

V
AC
V
USB
V
OUT
V
BAT
Break Before Make
System Capacitance
Powering System
USB is Charging System Capacitance
DPPM Mode
Hi
Low
PSEL
V
AC
V
USB
V
OUT
V
BAT
USB Input Current Limit is Reached.
DPPM Mode
AC Declared Not Present, USB Power Applied
bq24030, bq24031
bq24032A, bq24035, bq24038
www.ti.com ............................................................................................................................................... SLUS618H –AUGUST 2004–REVISED OCTOBER 2009
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) V
OUT
; output current, I
OUT
= 0.25 A; channel
4 (CH4) V
BAT
= 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, V
AC
<=V
BAT
+ 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 (6
th
div). The output starts to recover when the USB FET starts to limit the input current (7
th
div) and the output drops
to the V
(DPPM-REG)
threshold.
Figure 7. Remove AC – PWR XFER to USB
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Product Folder Link(s): bq24030, bq24031 bq24032A, bq24035, bq24038