Table of Contents
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Q1,
Q3, and
Q15, and to
a 5-volt regulator (U1), which
provides power
to
the microcomputer (U3).
All of the timing, monitoring, and
sensing
of the circuits
is performed by the microcomputer
(U3).
Upon power-up,
with no battery inserted, the microcomputer performs
a
self check
of its
read-only memory
(ROM),
random-ac-
cess
memory
(RAM),
and
timer.
Next, the microcomputer
momentarily turns on
all
four
LEDs
via
U3, pins 33
thru
36.
Then,
the microcomputer momentarily turns on
each
LED
in
the
sequence: yellow, orange,
red, and green.
Completing the self
check
with no
problems encountered,
the microcomputer turns
all
the
LEDs
off.
After the microcomputer self
check has been
com-
pleted, the microcomputer monitors the capacity coding
resistor
(RC) RC
IN
line
(U3,
pin
23), and
the thermistor
(RT) TEMP
IN
line
(U3,
pin
24)
for
battery indications.
When a
battery is inserted, the microcomputer again
momentarily turns on
each
LED
in
the
sequence:
yellow,
orange,
red,
and green.
Next, U3
checks
the
RC
and
RT
in
the battery to deter-
mine
charging conditions.
If
the
value
of the
battery's
RC
is
abnormal
(see Table
1),
the microcomputer
senses
a
problem and,
via
U3,
pin
36,
keys
the orange
LED
to
flash
on and
off.
If
the
RC
value
is normal, the microcomputer
proceeds
to monitor
the battery's temperature.
Table
1.
Normal
RC Values
If
the battery temperature is outside the temperature
window (below
10°C
(3.33Vdc
on the
RT
contact)
or
above 40°C (1.87Vdc
on the
RT
contact),
the microcom-
puter lights the yellow
Stand-By LED
and waits
for
the
battery's temperature
to fall within
the temperature win-
dow.
Once
this occurs, the microcomputer turns
off
the
yellow
LED
(if turned on at all)
and turns on the charging
circuits; these circuits condition the battery by charging
it
at
600mA
for
30 seconds. At
the end of
30 seconds,
the
microcomputer
checks
the battery
voltage via
the
VCHG
IN
line at U3, pin 22.
The
voltage should be between 7Vdc
and
11Vdc.
If
the
voltage
is
outside this range, the
microcomputer
senses
the battery problem and indicates
it
by flashing the orange
LED
(RESEAT/REPLACE THE
BATTERY).
b.
Charging Circuits
Following
the power-up, microcomputer self
check,
battery installation, and normal battery
RC,
RT,
and vol-
tage checks,
rapid
charging begins. There are
four rapid-
charge
rates
as
indicated by the battery
RC
(see
Table 2).
Table
2.
Charge Rates
CHARGE RATE (mA)
BATTERY TYPE
RAPID
TRICKLE
600
50
NTN4537A, NTN4592A
NTN4819A, NTN4820A
780
NTN4538A, NTN4593A,
1080
90
NTN4657A, NTN4671A
NTN4539A, NTN4594A
1500
125
NTN4595A, NTN4596A,
1500
10
NTN4992A
65
The
signal
at pin
5
of
op amp
U2B (voltage
drop
across
resistor
R6)
is amplified by
U2B.
The
op amp's output (pin
7), sensed by the microcomputer
on the
CURRENT
iN
line
(U3,
pin 21),
is used by the microcomputer
to
select
the resistance
(R23
thru
R33)
required to
achieve
the
proper
voltage
level at the input (pin 3) of op amp U2A.
The
resultant output at
U2A,
pin
1,
drives transistor Q7,
which drives transistors
Q3
and
Q1.
The
microcomputer,
via a
high at U3,
pin
29, turns
on
switching transistor Q8, achieving
a
lower emitter resis-
tance
at
Q7
for the
rapid-charge condition. At the same
time U3,
pin 34,
goes
high to turn on
a display board driver
transistor, which illuminates the red
Charging LED. As
the battery rapid
charges,
the microcomputer monitors
the current (U3,
pin 21)
every 30 seconds
and
makes ad-
justments (selection
of
resistors
R23
thru
R33) as neces-
sary
to
maintain constant
charging
current.
The
microcomputer monitors the battery
voltage
on
the
VCHG
IN
line
(U3,
pin
22). Should this voltage ap-
proach 11Vdc, the microcomputer
will
cut
back
the
charg-
ing current and maintain
a constant voltage charge.
RCVALUE
BATTERY TYPE
Every
three minutes, the microcomputer stops the
charging
current and
checks
the temperature of the bat-
tery
via
the
TEMP
IN
line
(U3,
pin
24).
As
the battery
reaches
full
charge
in
the rapid-charge mode, the battery
temperature rises.
When
the rate of
increase
within the
three minutes
exceeds
1.6°C (8OmV), U3, pin
29,
goes
low,
Q8
turns
off,
and the charger
switches
to
the trickle-
charge
mode.
At the same
time, U3, pin
34,
goes
low
to
turn off
the red
Charging LED,
and U3,
pin
35,
goes
high
to turn
on
a driver transistor and the green
Complete
LED.
In
any temperature environment, should
the battery
temperature reach
45°C,
the charger
will
switch
to
the
trickle-charge mode.
2.4k0,
NTN4537A, NTN4592A
§.1kO
NTN4538A, NTN4593A, NTN4657A, NTN4671A
10k.
NTN4539A, NTN4594A
18k0,
NTN4595A, NTN4596A, NTN4992A
33kN
NTN4819A, NTN4820A
In
the
trickle-charge
(Complete)
mode,
as
in
the rapid-
charge
mode, the microcomputer monitors the charging
current and
makes
the
necessary adjustments every 30
seconds.
The
trickle current
charge rates are shown
in
Table
2.
Whenever a
high- or ultra-high-capacity battery is in-
stalled, transistors Q17 and
@15
are turned
on,
via a
logi-
cal
high from U3, pin 32. Q17 and Q15 pull
charging
current from transistor
Q1
through parallel resistors
R47
and
R60.
3
Q1,
Q3, and
Q15, and to
a 5-volt regulator (U1), which
provides power
to
the microcomputer (U3).
All of the timing, monitoring, and
sensing
of the circuits
is performed by the microcomputer
(U3).
Upon power-up,
with no battery inserted, the microcomputer performs
a
self check
of its
read-only memory
(ROM),
random-ac-
cess
memory
(RAM),
and
timer.
Next, the microcomputer
momentarily turns on
all
four
LEDs
via
U3, pins 33
thru
36.
Then,
the microcomputer momentarily turns on
each
LED
in
the
sequence: yellow, orange,
red, and green.
Completing the self
check
with no
problems encountered,
the microcomputer turns
all
the
LEDs
off.
After the microcomputer self
check has been
com-
pleted, the microcomputer monitors the capacity coding
resistor
(RC) RC
IN
line
(U3,
pin
23), and
the thermistor
(RT) TEMP
IN
line
(U3,
pin
24)
for
battery indications.
When a
battery is inserted, the microcomputer again
momentarily turns on
each
LED
in
the
sequence:
yellow,
orange,
red,
and green.
Next, U3
checks
the
RC
and
RT
in
the battery to deter-
mine
charging conditions.
If
the
value
of the
battery's
RC
is
abnormal
(see Table
1),
the microcomputer
senses
a
problem and,
via
U3,
pin
36,
keys
the orange
LED
to
flash
on and
off.
If
the
RC
value
is normal, the microcomputer
proceeds
to monitor
the battery's temperature.
Table
1.
Normal
RC Values
If
the battery temperature is outside the temperature
window (below
10°C
(3.33Vdc
on the
RT
contact)
or
above 40°C (1.87Vdc
on the
RT
contact),
the microcom-
puter lights the yellow
Stand-By LED
and waits
for
the
battery's temperature
to fall within
the temperature win-
dow.
Once
this occurs, the microcomputer turns
off
the
yellow
LED
(if turned on at all)
and turns on the charging
circuits; these circuits condition the battery by charging
it
at
600mA
for
30 seconds. At
the end of
30 seconds,
the
microcomputer
checks
the battery
voltage via
the
VCHG
IN
line at U3, pin 22.
The
voltage should be between 7Vdc
and
11Vdc.
If
the
voltage
is
outside this range, the
microcomputer
senses
the battery problem and indicates
it
by flashing the orange
LED
(RESEAT/REPLACE THE
BATTERY).
b.
Charging Circuits
Following
the power-up, microcomputer self
check,
battery installation, and normal battery
RC,
RT,
and vol-
tage checks,
rapid
charging begins. There are
four rapid-
charge
rates
as
indicated by the battery
RC
(see
Table 2).
Table
2.
Charge Rates
CHARGE RATE (mA)
BATTERY TYPE
RAPID
TRICKLE
600
50
NTN4537A, NTN4592A
NTN4819A, NTN4820A
780
NTN4538A, NTN4593A,
1080
90
NTN4657A, NTN4671A
NTN4539A, NTN4594A
1500
125
NTN4595A, NTN4596A,
1500
10
NTN4992A
65
The
signal
at pin
5
of
op amp
U2B (voltage
drop
across
resistor
R6)
is amplified by
U2B.
The
op amp's output (pin
7), sensed by the microcomputer
on the
CURRENT
iN
line
(U3,
pin 21),
is used by the microcomputer
to
select
the resistance
(R23
thru
R33)
required to
achieve
the
proper
voltage
level at the input (pin 3) of op amp U2A.
The
resultant output at
U2A,
pin
1,
drives transistor Q7,
which drives transistors
Q3
and
Q1.
The
microcomputer,
via a
high at U3,
pin
29, turns
on
switching transistor Q8, achieving
a
lower emitter resis-
tance
at
Q7
for the
rapid-charge condition. At the same
time U3,
pin 34,
goes
high to turn on
a display board driver
transistor, which illuminates the red
Charging LED. As
the battery rapid
charges,
the microcomputer monitors
the current (U3,
pin 21)
every 30 seconds
and
makes ad-
justments (selection
of
resistors
R23
thru
R33) as neces-
sary
to
maintain constant
charging
current.
The
microcomputer monitors the battery
voltage
on
the
VCHG
IN
line
(U3,
pin
22). Should this voltage ap-
proach 11Vdc, the microcomputer
will
cut
back
the
charg-
ing current and maintain
a constant voltage charge.
RCVALUE
BATTERY TYPE
Every
three minutes, the microcomputer stops the
charging
current and
checks
the temperature of the bat-
tery
via
the
TEMP
IN
line
(U3,
pin
24).
As
the battery
reaches
full
charge
in
the rapid-charge mode, the battery
temperature rises.
When
the rate of
increase
within the
three minutes
exceeds
1.6°C (8OmV), U3, pin
29,
goes
low,
Q8
turns
off,
and the charger
switches
to
the trickle-
charge
mode.
At the same
time, U3, pin
34,
goes
low
to
turn off
the red
Charging LED,
and U3,
pin
35,
goes
high
to turn
on
a driver transistor and the green
Complete
LED.
In
any temperature environment, should
the battery
temperature reach
45°C,
the charger
will
switch
to
the
trickle-charge mode.
2.4k0,
NTN4537A, NTN4592A
§.1kO
NTN4538A, NTN4593A, NTN4657A, NTN4671A
10k.
NTN4539A, NTN4594A
18k0,
NTN4595A, NTN4596A, NTN4992A
33kN
NTN4819A, NTN4820A
In
the
trickle-charge
(Complete)
mode,
as
in
the rapid-
charge
mode, the microcomputer monitors the charging
current and
makes
the
necessary adjustments every 30
seconds.
The
trickle current
charge rates are shown
in
Table
2.
Whenever a
high- or ultra-high-capacity battery is in-
stalled, transistors Q17 and
@15
are turned
on,
via a
logi-
cal
high from U3, pin 32. Q17 and Q15 pull
charging
current from transistor
Q1
through parallel resistors
R47
and
R60.
3
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