Datasheet

V
AC
V
USB
V
OUT
V
BAT
DPPM Mode
BreakBeforeMake
V
AC
V
USB
V
OUT
V
BAT
DPPMMode
V
OUT
ReturnstoRegulation(4.4V,bq24032A)
ChargingCurrentReturnstoI
pgm
bq24030, bq24031
bq24032A, bq24035, bq24038
SLUS618H –AUGUST 2004–REVISED OCTOBER 2009............................................................................................................................................... www.ti.com
Figure 8 illustrates when AC (low battery) is removed, 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
= 2.25 V; and I
(PGM-CHG)
= 1 A. This figure is the same as where the battery has more capacity. Note that
the output drops to the battery voltage before switching to USB power. A resistor divider between AC and ground
tied to PSEL can toggle the power transfer earlier if necessary.
Figure 8. Remove AC (Low Battery) – PWR XFER to USB
Figure 9 illustrates when AC is applied, power transfers from USB to AC; 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
=
3.5 V; and I
(PGM-CHG)
= 1 A. The charger is set for AC priority but is running off USB until AC is applied. When AC
is applied (1
st
div) and the USB FET opens (2
nd
div), the AC FET closes (3
rd
div) and the output recovers from
the DPPM threshold (8
th
div).
Figure 9. Apply AC – PWR XFER From USB to AC
18 Submit Documentation Feedback Copyright © 2004–2009, Texas Instruments Incorporated
Product Folder Link(s): bq24030, bq24031 bq24032A, bq24035, bq24038