AIC1781
Battery Charge Controller
Analog Integrations Corporation 4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC www.analog.com.tw
DS-1781-00 TEL: 886-3-5772500 FAX: 886-3-5772510 1
onesansinv
FEATURES
tensans Fast Charge Control of NiMH/NiCd Batteries,
even with a Fluctuating Charging Current.
tensans Fast Charge Termination by:
∆∆T / t
,
−∆V
,
0V∆
, Safety Timer, Maximum Temperature,
Maximum Voltage.
tensans Linearly Adjustable
∆∆T / t
Detection Slope and
Safety Timer.
tensans Adjustable Peak Voltage Timer for
0V∆
.
tensans Battery Voltage Protection Range Selectable.
tensans Selectable Battery Temperature Protection
Mode.
tensans Protection against Battery Voltage and Battery
Temperature Faults.
tensans Selectable LED Display Mode for Battery Status.
tensans Five Pulsed Trickle Charge Modes.
tensans Discharge-before-Charge Function Available for
Eliminating Memory Effect.
tensans Quick and Easy Testing for Production.
tensans 16-pin DIP or SO Packages.
onesansinv
APPLICATIONS
Battery Fast Chargers for:
tensans Mobile Phones.
tensans Notebook and Laptop Personal Computers.
tensans Portable Power Tools and Toys.
tensans Portable Communication Equipments.
tensans Portable Video & Stereo Equipments.
0 102030405060
1.15
1.25
1.35
1.45
1.55
100
80
60
40
20
Tem
per
atur
e (
°
C)
Temperature
Cell Voltage
Ce
ll Vo
lta
g
e
(
V
)
Charge Time (min.)
Charge Current = 600 mA
Cell Capacity = 550 mA
NiMH Battery
Fig. 1 Battery Charging Characteristics Resulting
from an AIC1781-Controlled Charger with a
Fluctuating Charging Current
onesansinv
DESCRIPTION
The AIC1781 fast charge controller IC is designed
for intelligent charging of NiMH or NiCd batteries
without the risk of overcharge.
−∆V
detection
(-0.25%),
0V∆
detection (peak voltage timer)
and
∆∆T / t
detection are the primary methods
employed by the AIC1781 to terminate fast charge.
The fast charge can also be cut off by maximum
battery voltage and maximum battery temperature
detection along with the safety timer to prevent
charging under fault conditions of the charging
system or the battery itself.
Both
∆∆T / t
and
−∆V
detection methods have
been proved powerful in terminating fast charging
for NiMH and NiCd batteries. The AIC1781 utilizes
the combination of these two methods to achieve
reliable decision of ending fast charge and prevent
misaction caused by using
−∆V
detection alone
under certain conditions. Fig. 1 shows an example
of charging curve of a battery charged by a
fluctuating current from a NiMH battery charger
which uses the AIC1781 controller IC to achieve
optimal charging. This technique, in cooperating
with the
0V∆
detection (peak voltage timer), is
particularly suitable for NiMH batteries, whose
voltage drop is hardly significant yet temperature
rises rapidly. The
∆∆T / t
or
−∆V
detection
circuitry may be disabled independently for
different applications, such as system-integrated
chargers, chargers with varying charge current, or
battery packs lack of temperature sensing
thermistor.
The safety timer period, mode of battery
temperature protection, battery voltage protection
range, pulsed trickle charge duty, and LED display
mode are all adjustable or selectable. Discharge-
before-charge function is included to get rid of
memory effect of NiCd batteries without the risk of
overdischarging. Test mode is provided for charger
manufactures to dramatically reduce production
test time.