BQ24030_07 Datasheet, PDF (18/38 Pages) Texas Instruments – SINGLE-CHIP CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC (bqTINY)

bq24030, bq24031, bq24032A
bq24035, bq24038
SLUS618F – AUGUST 2004 – REVISED NOVEMBER 2006
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.
V_USB
V_OUT
DPPM Mode
V_AC
V_BAT
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).
Break Before Make
V_AC
V_USB
V_OUT
V_BAT
V_OUT Returns to Regulation (4.4 V, bq24032A)
Charging Current Returns to I_pgm
DPPM Mode
Figure 9. Apply AC – PWR XFER From USB to AC
18
Submit Documentation Feedback