Datasheet

V
AC
V
USB
V
OUT
V
BAT
DPPM Mode
USB Declared not Present
AC is Applied (USB Mode)
AC Hits USB (ISET2) limit
V
AC
V
USB
V
OUT
V
BAT
Charging (Step) Followed by Charge Done
BAT PIN Capacitance Discharging to Refresh Threshold
bq24030, bq24031
bq24032A, bq24035, bq24038
www.ti.com ............................................................................................................................................... SLUS618H –AUGUST 2004–REVISED OCTOBER 2009
Figure 10 illustrates when USB is removed, power transfers from USB to AC; PSEL = L; 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 USB source is removed (2
nd
div) and the output drops to the battery voltage
(declares USB bad, 4
th
div) and switches to AC (in USB mode) and recovers similar to the figure that is switching
to USB power. This power transfer occurred with PSEL low, which means that the AC input is regulated as if it
were a USB.
Figure 10. Remove USB – PWR XFER From USB to AC
Figure 11 illustrates when the battery is absent, power transfers to USB; PSEL = H; 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
;
I
(PGM-CHG)
= 1 A. Note the saw-tooth waveform due to cycling between charge done and refresh (new charge).
Figure 11. Battery Absent – PWR XFER to USB
Copyright © 2004–2009, Texas Instruments Incorporated Submit Documentation Feedback 19
Product Folder Link(s): bq24030, bq24031 bq24032A, bq24035, bq24038