Diodes AUR9807 - Manual (Page 14)

Data Sheet
Single-cell Li-Ion Charger IC with System Power Management AUR9807
Nov. 2011 Rev. 1. 0 BCD Semiconductor Manufacturing Limited
14
Power Flow
The AUR9807 selects the power source automatically.
In the absence of the input source (AC adapter or USB),
the battery is chosen to power the system. Under this
circumstance, the AUR9807 consumes less than 5µ
Ampere; the power path resistance from the battery to
the system is only 40mΩ
(3) ; all these guarantee a high
efficiency and elongate the battery discharge time. With
this stringent sleep current budget (<5µA), the
AUR9807 is still able to detect an output short
condition and cuts off the power path between the
battery and the system under short condition.
With the input power present, the MODE pin sets the
AUR9807 in adapter mode or USB mode. In adapter
mode, the AUR9807 does not limit the total current
directly, current limiting phenomenon occurs through
Adaptive Power Management in response to the output
voltage drop. The resistor connected to ISET1 pin sets
the maximum charging current. This maximum
charging current can be halved by pulling down the
ISET2 pin. In USB mode, the AUR9807 will limit the
total current within 450mA (ISET2=High) or 90mA
(ISET2=Low). The maximum charging current is still
set by the resistor connected to ISET1 pin; however,
because of this current limiting feature, the actual
charging current is usually less than 450mA (or 90mA).
(3) Q2 design value is 40mΩ.
Power Source Selection and Charge Current Setting
MODE Pin
Level
AC Adapter
Loading Power
Source
Charge Current Setting
Yes USB ISET1, limitation depends on ISET2 setting
Low
No Battery N/A
Yes AC Adapter ISET1, half charging rate by setting ISET2 to low
High
No Battery N/A