U2402B
Fast-Charge Controller for NiCd/NiMH Batteries
Description
The fast-charge battery controller circuit, U2402B, uses
bipolar technology. The IC enables the designer to create
an efficient and economic charge system. The U2402B
incorporates intelligent multiple-gradient battery-
voltage monitoring and mains phase control for power
management. With automatic top-off charging, the
integrated circuit ensures that the charge device stops
regular charging before the critical stage of overcharging
is achieved. It has two LED driver indications for charge
and temperature status.
Features
D
D
D
D
D
D
D
Multiple gradient monitoring
Temperature window (T
min
/T
max
)
Exact battery voltage measurement without charge
Phase control for charge-current regulation
Top-off and trickle charge function
Two LED outputs for charge status indication
Disabling of d
2
V/dt
2
switch-off criteria
during battery formation
Applications
D
D
D
D
D
D
Portable power tools
Laptop/notebook personal computer
Cellular/cordless phones
Emergency lighting systems
Hobby equipment
Camcorder
D
Battery-voltage check
Block Diagram
18 (20) 17 (19)
16 (18)
14 (15)
13 (14)
12 (13)
11 (12)
Sync
ö
C
ö
R
V
Ref
6.5 V/10 mA
Oscillator
Status control
3 (3)
Phase control
V
ö
i
4 (4)
Scan path
1 (1)
Control unit
Trigger output
Gradient
d
2
V/dt
2
and –dV
Power - on control
Battery
detection
V
Ref
= 5 V
10 (11)
V
Batt
Monitor
0.1 to 4 V
15 (17)
2 (2)
Power supply
V
S
= 8 to 26 V
160 mV
Ref
Temp. control
Sensor
T
max
Charge break
output
5 (5)
6 (6)
7 (8)
8 (9)
9 (10)
( ) SO 20, Pins 7 and 16 n.c.
Figure 1. Block diagram
Order Information
Extended Type Number
U2402B-x
U2402B-xFL
U2402B-xFLG3
Package
DIP18
SO20
SO20
Remarks
Tube
Tube
Taped and reeled
Rev. A4, 08-Nov-99
1 (18)
U2402B
Pin Description
Output
1
18 V
sync
17
ö
C
16
ö
R
15 V
S
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Symbol
Output
GND
LED2
V
ö
i
OP
O
OP
I
T
max
Sensor
t
p
V
Batt
LED1
S
TM.
Osc
V
Ref
V
S
ö
R
ö
C
GND 2
LED2
V
ö
i
OP
O
OP
I
T
max
3
4
5
6
7
U2402B
14 V
Ref
13 Osc
12 S
TM.
11 LED1
10 V
Batt
Sensor 8
t
p
9
Figure 2. Package: DIP18
V
sync.
Function
Trigger output
Ground
Display output “Green”
Phase angle control input voltage
Operational amplifier output
Operational amplifier input
Maximum temperature
Temperature sensor
Charge break output
Battery voltage
LED display output “Red”
Test mode switch (status control)
Oscillator
Reference output voltage
Supply voltage
Ramp current resistance
Ramp voltage – capacitance
Mains synchronization input
Output
1
20
19
18
17
V
sync
GND 2
LED2
V
ö
i
OP
O
OP
I
3
4
5
6
ö
ö
C
R
V
S
n.c.
V
Ref
Osc
S
TM.
U2402B
16
15
14
13
n.c. 7
T
max
8
Sensor 9
t
p
10
12 LED1
11
V
Batt
Figure 3. Package: SO20
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Symbol
Output
GND
LED2
V
ö
i
OP
O
OP
I
n.c.
T
max
Sensor
t
p
V
Batt
LED1
S
TM.
Osc
V
Ref
n.c.
V
S
ö
R
ö
C
V
sync.
Function
Trigger output
Ground
Display output “Green”
Phase angle control input voltage
Operational amplifier output
Operational amplifier input
Not connected
Maximum temperature
Temperature sensor
Charge break output
Battery voltage
LED display output “Red”
Test mode switch (status control)
Oscillator
Reference output voltage
Not connected
Supply voltage
Ramp current resistance
Ramp voltage – capacitance
Mains synchronization input
2 (18)
Rev. A4, 08-Nov-99
Rev. A4, 08-Nov-99
Figure 4. Block diagram with external circuit (DIP pinning)
D4
Mains
D5
T1
BC 308
D2
Th1
R10
R8
1k
W
D1
R1
100 k
10
W
R2
D6
2x
560
W
W
W
R3
0.1 F
C6
R13
C3
10 nF
17
Sync
ϕ
16
ϕ
R
560 k
R4
m
From
RT1 / RT2
From Pin 15
VS
10 nF
R5
1k
10 k
W
0.22 F
W
m
R0
270 k
W
D7
Red
D8
Green
D3
Th2
R11
R9
10 k
2.2 k
R7
C2
14
VRef
6.5 V/10 mA
W
13
C0
12
11
W
1 k
W
18
C
Phase control
V
ϕ
i
Oscillator
Status
control
3
To Pin 4
1
Control unit
Trigger output
Gradient
C1
470 F
VS 15
2
Power supply
VS = 8 to 26 V
d2 V/dt 2 & –dV
Scan path
RB2
C7
10 k
RB1
W
1k
I ch
W
Battery
detection
VRef = 5 V
VBatt Monitor
0.1 to 4 V
10
4.7 F
16 k
RB3
m
W
m
Battery
(4 cells)
Power on
control
DC
NTC
4
5
160 mV
Ref
6
Temp. control
Tmax Sensor
Charge break
output
1 F
160 mV
0.2
Rsh
R6
10 k
CR
m
1 F
C4
RT3
24 k
m
7
8
RT1 12 k
RT2
C8
0.1 F
100 k
W
9
To VRef (Pin 14)
U2402B
W
W
W
W
m
3 (18)
U2402B
General Description
The integrated circuit, U2402B, is designed for charging
Nickel-Cadmium (NiCd) and Nickel-Metal-Hydride
(NiMH) batteries. Fast charging results in voltage lobes
when fully charged (figure 5). It supplies two identifica-
tions ( i. e., + d
2
V/dt
2
, and –
D
V) to end the charge
operation at the proper time.
As compared to the existing charge concepts where the
charge is terminated
after voltage lobes
according
to –
D
V and temperature gradient identification, the
U2402B takes into consideration the additional changes
in positive charge curves, according to the second deriva-
tive of the voltage with respect to time (d
2
V/dt
2
). The
charge identification is the sure method of switching off
the fast charge before overcharging the battery. This helps
to give the battery a long life by hindering any marked
increase in cell pressure and temperature.
Even in critical charge applications, such as a reduced
charge current or with NiMH batteries where weaker
charge characteristics are present multiple gradient con-
trol results in very efficient switch-off.
An additional temperature control input increases not
only the performances of the charge switching character-
istics but also prevents the general charging of a battery
whose temperature is outside the specified window.
A constant charge current is necessary for continued
charge-voltage characteristic. This constant current regu-
lation is achieved with the help of internal amplifier phase
control and a simple shunt-current control technique.
All functions relating to battery management can be
achieved with DC-supply charge systems. A DC-DC-
converter or linear regulator should take over the function
of power supply. For further information please refer to
the applications.
*
*
Battery insertion
V
10
5V
Gradient recognition
)
ddtV
2
2
Battery
voltage
check
–
D
V
–
D
V,
–
D
V
monitoring
)
ddtV ,
2
2
active
shorted batteries ignored
t
Fast charge rate I
O
Battery
formation
t
1
= 5 min
Figure 5. Charge function diagram, f
osc
= 800 Hz
Top off
charge rate
1/4 I
O
t
2
v
20 min
Trickle
charge rate
1/256 I
O
4 (18)
Rev. A4, 08-Nov-99
U2402B
Flow Chart Explanation,
f
osc
= 800 Hz (Figures 4, 5 and 6)
Battery pack insertion disables the voltage lock at battery
detection input Pin 10. All functions in the integrated
circuit are reset. For further description, DIP-pinning is
taken into consideration.
Top-Off Charge Stage
By charge disconnection through the + d
2
V/dt
2
mode, the
device switches automatically to a defined protective
top-off charge with a pulse rate of 1/4 I
O
(pulse time,
t
p
= 5.12 s, period, T = 20.48 s).
The top-off charge time is specified for a time of
20 minutes @ 800 Hz.
Battery Insertion and –dV Monitoring
The charging procedure will be carried out if battery
insertion is recognised. If the polarity of the inserted
battery is not according to the specification, the fast
charge rate will stop immediately. After the polarity test,
if positive, the defined fast charge rate, I
O
, begins for the
first 5 minutes according to –dV monitoring. After
5 minutes of charging, the first identification control is
executed.
If the inserted battery has a signal across its terminal of
less than 0.1 V, then the charging procedure is interrupted.
This means that the battery is defective i.e., it is not a
rechargeable battery – “shorted batteries ignored”.
Voltage and temperature measurements across the battery
are carried out during charge break interval (see figure 8),
i.e., currentless or idle measurements.
If the inserted battery is
fully charged,
the –dV control
will signal a charge stop after six measurements
(approximately 110 seconds). All the above mentioned
functions are recognised during the first 5 minutes
according to –dV method. During this time, +d
2
V/dt
2
remains inactive. In this way the battery is protected from
unnecessary damage.
Trickle Charge Stage
When top-off charge is terminated, the device switches
automatically to trickle charge with 1/256 I
O
(t
p
= 5.12 s,
period = 1310.72 s). The trickle continues until the
battery pack is removed.
Basic Description
Power Supply (Figure 4)
The charge controller allows the direct power supply of
8 to 26 V at Pin 15. Internal regulation limits higher input
voltages. Series resistance, R
1
, regulates the supply
current, I
S
, to a maximum value of 25 mA. Series
resistance is recommended to suppress the noise signal,
even below 26 V limitation. It is calculated as follows:
R
1min
R
1max
w
V25–26 V
mA
max
d
2
V/dt
2
-Gradient
If there is no charge stop within the first 5 minutes after
battery insertion, then d
2
V/dt
2
monitoring will be active.
In this actual charge stage, all stop-charge criteria are
active.
v
V
min
– 8 V
I
tot
where
I
tot
= I
S
+ I
RB1
+ I
1
V
max,
V
min
= Rectified voltage
When close to the battery’s capacity limit, the battery
voltage curve will typically rise. As long as the +d
2
V/dt
2
stop-charging criteria are met, the device will stop the fast
charge activities.
I
S
= Current consumption (IC) without load
I
RB1
= Current through resistance, R
B1
I
1
= Trigger current at Pin 1
Rev. A4, 08-Nov-99
5 (18)
单片机
