SS6781B Datasheet, PDF (1/20 Pages) Silicon Standard Corp. – Battery Charge Controller

SS6781B
Battery Charge Controller
FEATURES
Fast Charge Control of NiMH/NiCd Batteries,
even with a Fluctuating Charging Current.
Fast Charge Termination by: ^{∆T / ∆t} , ^{−∆V} ,
0∆V _{, Safety Timer, Maximum Temperature,}
Maximum Voltage.
Linearly Adjustable ^{∆T / ∆t} Detection Slope and
Safety Timer.
Adjustable Peak Voltage Timer for ^0∆V .
Battery Voltage Protection Range Selectable.
Selectable Battery Temperature Protection
Mode.
Protection against Battery Voltage and Battery
Temperature Faults.
Selectable LED Display Mode for Battery Status.
Five Pulsed Trickle Charge Modes.
Discharge-before-Charge Function Available for
Eliminating Memory Effect.
Quick and Easy Testing for Production.
16-pin DIP or SO Packages.
APPLICATIONS
Battery Fast Chargers for:
Mobile Phones.
Notebook and Laptop Personal Computers.
Portable Power Tools and Toys.
Portable Communication Equipments.
Portable Video & Stereo Equipments.
1.55
100
Charge Current = 600 mA
Cell Capacity = 550 mA
NiMH Battery
1.45
80
Cell Voltage
1.35
60
1.25
Temperature
1.15
0
10
20
30
40
50
Charge Time (min.)
40
20
60
Fig. 1 Battery Charging Characteristics Resulting from
an SS6781B-Controlled Charger with a
Fluctuating Charging Current
Pb-free; RoHS-compliant
DESCRIPTION
The SS6781B fast charge controller IC is
designed for intelligent charging of NiMH or NiCd
batteries without the risk of overcharge. ^{−∆V}
Detection (-0.25%), ^0∆V detection (peak voltage
timer) and ^{∆T / ∆t} detection are the primary
methods employed by the SS6781B 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 SS6781B
utilizes the combination of these two methods to
achieve reliable decision of ending fast charge and
prevent misacting 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 SS6781B controller IC to achieve
optimal charging. This technique, in cooperating
with the ^0∆V 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
01/31/2008 Rev.1.00
www.SiliconStandard.com
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