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TEA1103 View Datasheet(PDF) - Philips Electronics

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TEA1103 Datasheet PDF : 28 Pages
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Philips Semiconductors
Fast charge ICs for NiCd and NiMH
batteries
Preliminary specification
TEA1103; TEA1103T;
TEA1103TS
INTRODUCTION
All battery types are initially fast charged with an
adjustable high current. Fast charge termination depends
upon the battery type. With NiCd and NiMH batteries the
main fast charge termination will be the T/t (temperature
detection) and/or peak voltage detection.
The fast charge period is followed by a top-off period for
NiCd and NiMH batteries. During the top-off period the
NiCd and NiMH batteries are charged to maximum
capacity by reduced adjustable charge current.
The top-off period ends after time-out or one hour
respectively.
After the top-off period, the TEA1103x switches over to the
standby mode. For NiCd and NiMH batteries either the
voltage regulation or trickle charge mode can be selected.
The voltage regulation mode is selected when the battery
includes a fixed load. Trickle charge prevents a discharge
of the battery over a long period of time.
Charging principles
CHARGING NiCd/NiMH BATTERIES
Fast charging of the battery begins when the power supply
voltage is applied and at battery insertion.
During fast charge of NiCd and NiMH batteries, the battery
temperature and voltage are monitored. Outside the
initialized temperature and voltage window, the system
switches over to the top-off charge current.
The TEA1103x supports detection of fully charged NiCd
and NiMH batteries by either of the following criteria:
• ∆T/t
Voltage peak detection.
If the system is programmed with T/t and Vpeak or, T/t
or Vpeak as the main fast charge termination, it
automatically switches to voltage peak detection if the
battery pack is not provided with a temperature sensing
input (NTC). In this way both packages, with and without
temperature sensor, can be used randomly independent of
the applied full detection method. Besides T/t and/or
voltage peak detection, fast charging is also protected by
temperature cut-off and time-out.
To avoid false fast charge termination by peak voltage
detection or T/t, full detection is disabled during a short
hold-off period at the start of a fast charge session.
After fast charge termination, the battery is extra charged
by a top-off period. During this period of approximately one
hour, the charge current is lowered thus allowing the
battery to be charged to nearly 100% before the system
switches over to standby.
After the battery has been charged to nearly 100% by the
top-off period, discharge of the battery (caused by a load
or by the self-discharge) can be avoided by voltage
regulation or by trickle charge.
If batteries are charged in combination with a load, the
TEA1103x can be programmed to apply voltage regulation
during the standby mode. In this way, discharge of the
battery caused by self-discharge or by an eventual load is
avoided. The regulating voltage is adjustable to the
voltage characteristic of the battery. For battery safety the
charge current is limited and the temperature is monitored
during voltage regulation. If a trickle charge is applied, the
self-discharge of the battery will be compensated by a
pulsating charge current.
To avoid the so called ‘memory effect’ in NiCd batteries, a
refresh can be manually activated. The discharge current
is regulated by the IC in combination with an external
power transistor. After discharging the battery to 1 V per
cell, the system automatically switches over to fast charge.
FUNCTIONAL DESCRIPTION
Control logic
The main function of the control logic is to support the
communication between several blocks. It also controls
the charge method, initialization and battery full detection.
The block diagram of the TEA1103x is illustrated in Fig.1.
Conditioning charge method and initializations
At system switch-on, or at battery insertion, the control
logic sets the initialization mode in the timer block.
After the initialization time the timer program pins can be
used to indicate the charging state using several LEDs.
The charge method is defined at the same time by the
following methods:
If the FCT pin is floating, the system will charge the
battery according to the charge characteristic of NiCd
and NiMH batteries.
The standby charge method (NiCd and NiMH), trickle
charge or voltage regulation, is defined by the input pin
Vstb. By biasing this voltage with a set voltage, the output
voltage will be regulated to the Vstb set voltage. If this pin
is connected to VS, or no NTC is connected the system
applies trickle charge.
1999 Jan 27
6
 

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