CM9100 Datasheet, PDF (9/11 Pages) California Micro Devices Corp – Basic Compact Cost-effective Fast-Charger

PRELIMINARY
CM9100
Application Information (cont’d)
provides an absolute OTP shutdown at junction tem-
perature of 150°C.
Charging status
CM9100 provides a charging status indicator pin: STAT.
This is an open-drain output, which can drive an LED
directly, with up to 20mA of current sinking capability.
Alternatively, the system supervisory microprocessor
can monitor the battery charging status by interfacing
with this pin, using a 100kΩ pull-up resistor. See Table
1.
CHARGE STATUS
Precharge in progress
Fast-charge in progress
Charge completed
Charge suspended (OTP,
OCP)
STAT
Low -
Low -
High -
High -
Table 1: Charge Status for STAT
drops below the re-charge threshold, a new charge
cycle begins.
Shutdown mode is triggered by a charging fault.
These include, Input current that exceeds 2.4A (OCP),
the IC junction temperature exceeds 150°C (OTP).
Charging stops.
Sleep mode is entered when the Adapter is removed
(or is the wrong voltage). Charging stops. In this mode,
the CM9100 draws less than 1µA of current from the
battery.
Component Selection
The constant voltage AC Adapter must be selected
carefully to minimize power losses and heat dissipation
in the charger. The input supply should be between
5.0V and 6.0V. The lowest allowable input voltage will
minimize heat dissipation and simplify the thermal
design.
Charging Control by the Host System
The CM9100 allows a host-system to take active con-
trol of the charging process by providing actual charg-
ing current monitoring via the 1000:1 current mirror on
R_ISET. This is especially useful for the system’s direct
control of the Termination threshold (preset to 5% of
CC mode level).
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.
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.
Standby mode is entered after a successful Termina-
tion mode and charging is done. Charging stops. In this
mode, the battery is monitored, and when its voltage
Layout Considerations
Because the internal thermal foldback circuit will limit
the current when the IC reaches 105°C it is important
to keep a good thermal interface between the IC and
the PC board. It is critical that the exposed metal on
the backside of the CM9100 be soldered to the PCB
ground. The Cu pad should is large and thick enough
to provided good thermal spreading. Thermal vias to
other Cu layers provide improved thermal perfor-
mance.
V_IN and V_OUT are high current paths and the traces
should be sized appropriately for the maximum current
to avoid voltage drops.
© 2006 California Micro Devices Corp. All rights reserved.
06/30/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: [phone] l Fax: [phone] l www.cmd.com
9