CM9112 Datasheet, PDF (14/18 Pages) California Micro Devices Corp – Dual Inputs Dual Outputs High Accurate Fast Charger

PRELIMINARY
CM9112
Application Information (cont’d)
A value of 0.1µF provides a 13.6ms clock cycle period,
producing 30 minutes for Timeout1 (Precharge) and 60
minutes for Timeout2 (Termination),.
When VIN is applied to a fully discharged battery
(V_BAT<3.0V), the internal counter starts counting clock
cycles for Timeout1. A constant Precharge current
(10% of the programmed Fast-charging current) then
charges the battery. If Timeout1 elapses before the
battery reaches the 3.3V threshold of the Fast-charge
(CC) mode, charging stops and a Charge Suspended
fault is signaled by the status pins
(STAT1=STAT2=V_IN). This is a latched status and
charging can only resume by toggling V_IN.
If the battery voltage attains 3.3V before Timeout1
elapses, the internal counter is reset without any action
from the charging algorithm and the battery goes into
the Fast-charge mode.
During the Fast-charge mode, there is no Timeout
counting, and, in theory, this mode can last indefinitely.
During Fast-charge, the battery could be providing cur­
rent to a load. With only part of the available charging
current going into the battery, the charging time will
increase and becomes unpredictable. Thus, a Timeout
interval during this mode is not used, allowing greater
application flexibility.
Once the battery reaches the 4.20V threshold, the Ter­
mination (CV) mode begins and the charging current
starts to decrease. At the same time, the internal clock
starts counting again. If Timeout2 elapsed before the
Termination current threshold is reached, charging
stops in a latched status (STAT1=STAT2=V_IN). It can
resume only by toggling VIN. If the Termination thresh­
old is reached before Timeout2 has elapsed, the
counter resets and the charger enters into the Standby
mode.
If a stop charge to the battery is triggered by Timeout1/
Timeout2, it should be noted that VSYS would continue
to provide power to the Baseband load.
Disabling the Timeouts
To allow design flexibility for many different applica­
tions, the CM9112 allows disabling the Timeout inter­
vals as an option. If the application does not require
Timeout Intervals to control Precharge and Termina­
tion, connecting the CT pin to VIN will disable the func­
tion. The charging algorithm then will be controlled only
by voltage on the BSENS pin (Battery Sense Voltage).
Mode Summary
Precharge mode is the typical charge starting mode
for pre-conditioning a deeply discharged battery
(<3.3V). A constant current of 10% of the programmed
Fast-charge current is applied to raise the voltage
safely above 3.3V. The maximum charge time is limited
to the programmed Timeout1 period.
Fast-charge mode is the constant current charging
mode that applies most of the battery charge. A pro­
grammed constant current is applied to bring the bat­
tery voltage to 4.2V.
Termination mode is the final charging mode, where a
constant voltage of 4.2V is applied to the battery until
the charge current drops below 5% or the programmed
Fast-charge current. The charging time is limited by the
programmed Timeout2.
Standby mode is entered after a successful Termina­
tion mode and charging is done. Charging stops but
VSYS continue to be supplied by AC Adaptor input. In
this mode, the battery is monitored, and when its volt­
age drops below the re-charge threshold (4.100v), a
new charge cycle begins.
Shutdown– not latched mode is triggered by a charg­
ing fault. These include THERM pin voltage outside the
window (battery is too hot, too cold, or removed), or
pulling ENA pin low. The charging resumes if the failure
condition is removed. VSYS is still alive and supply
SYSTEM with current.
Shutdown– latched mode
If input current, sensed internally, exceeds 1.5A (OCP),
or the IC junction temperature exceeds 150°C (OTP).
The shutdown happens again but this time it is latched.
Only by toggling VAD/USB and removing the failure
condition the CM9112 could resume the function.
VSYS is no more supplied with current and an external
Q2 MOSFET connect VSYS with the Battery which
become the system power supplier.
Timer-fault mode is entered when a Timeout ends
without the battery reaching the proper threshold.
Charging stops and remains stopped until VIN is tog­
gled. VSYS will continue to receive power through
LDO1.
© 2006 California Micro Devices Corp. All rights reserved.
07/06/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 lTel: [phone] lFax: [phone] lwww.cmd.com
14