SS6781A Datasheet, PDF (1/18 Pages) Silicon Standard Corp. – Battery Charger Controller

SS6781A(G)
Battery Charger Controller
FEATURES
DESCRIPTION
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 or 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
Packaged in SO-16 or PDIP-16
This device is available with Pb-free lead finish.
APPLICATIONS
Fast Battery Chargers for:
Mobile Phones.
Notebook and Laptop Personal Computers.
Portable Power Tools and Toys.
Portable Communication Equipment.
Portable Video and Stereo Equipment.
1.55
100
Charge Current = 600 mA
Cell Capacity = 550 mA
NiMH Battery
1.45
80
Cell Voltage
60
1.35
1.25
Temperature
1.15
0
10
20
30
40
50
Charge Time (min.)
40
20
60
Fig. 1 Battery Charging Characteristics Resulting from
a SS6781A-Controlled Charger with a
Fluctuating Charging Current
The SS6781A fast charger controller IC is designed
for intelligent charging of NiMH or NiCd batteries
without the risk of overcharge.
Using -∆V detection (-0.25%), 0∆V detection
(peak voltage timer) and ∆T/∆t detection are the
primary methods employed by the SS6781A 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 SS6781A
utilizes the combination of these two methods to
reliably determine when to end fast charge and
prevent mistakes caused by using -∆ V detection
alone under certain conditions. Fig. 1 shows an
example of a charging curve for a battery charged
by a fluctuating current from a NiMH battery charger,
which uses the SS6781A controller IC to achieve
optimal charging. This technique, in conjunction
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 ∆TT//∆ tt or -∆ V detection
circuitry may be disabled independently for
different applications, such as system-integrated
chargers, chargers with varying charge current, or
battery packs which lack a temperature sensing
thermistor.
The safety timer period, battery temperature pro-
tection mode, battery voltage protection range,
pulsed trickle charge duty, and LED display mode
are all adjustable or selectable.
1/11/2005 Rev.2.10
www.SiliconStandard.com
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