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TELEFUNKEN Semiconductors Rev A3 Nov


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U2402B TELEFUNKEN Semiconductors Rev. A3, 14-Nov-96 1 (17) 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 Multiple gradient monitoring Temperature window (Tmin/Tmax) 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 d2V/dt2 switch-off criteria during battery formation Battery-voltage check Applications Portable power tools Laptop/notebook personal computer Cellular/cordless phones Emergency lighting systems Hobby equipment Camcorder Package: DIP18, SO20 Gradient d2V/dt2 and –dV 5 (5) Sync R Phase control 18 (20) 17 (19) 16 (18) Power supply VS = 8 to 26 V Trigger output Vi Power - on control VRef 6.5 V/10 mA 14 (15) Oscillator 160 mV Ref Temp.

  • output

  • off charge

  • multiple-gradient battery- voltage

  • vbatt battery

  • charge current

  • phase control

  • features multiple

  • dt2



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Fast Charge Controller for NiCd/NiMH Batteries
The fast-charge battery controller circuit, U2402B, uses management. With automatic top-off charging, the
bipolar technology. The IC enables the designer to create integrated circuit ensures that the charge device stops
an efficient and economic charge system. The U2402B regular charging, before the critical stage of overcharging
incorporates intelligent multiple-gradient battery- is achieved. It has two LED driver indications for charge
voltage monitoring and mains phase control for power and temperature status.
Features Applications
Multiple gradient monitoring Portable power tools
Temperature window (T /T )min max Laptop/notebook personal computer
Exact battery voltage measurement without charge
Cellular/cordless phones
Phase control for charge-current regulation
Emergency lighting systems
Top-off and trickle charge function
Hobby equipment
Two LED outputs for charge status indication
2 2 CamcorderDisabling of d V/dt switch-off criteria
during battery formation
Battery-voltage check Package: DIP18, SO20
11 (12)18 (20) 17 (19) 16 (18) 14 (15) 13 (14) 12 (13)
Sync VR RefC
6.5 V/10 mA Status control 3 (3)Phase control
V i
Scan path4 (4)
Control unit
1 (1) BatteryTrigger output
V = 5 VGradient Ref
2 2d V/dt and –dV 10 (11)
Power - on control
V MonitorBatt
0.1 to 4 V
15 (17)
Power supply
160 mV
Temp. controlV = 8 to 26 V Charge break2 (2) S Ref
T Sensor outputmax
5 (5) 7 (8) 8 (9)94 8585 6 (6) 9 (10)
( ) SO 20, Pins 7 and 16 NC
Figure 1. Block diagram
TELEFUNKEN Semiconductors 1 (17)
Rev. A3, 14-Nov-96
Pinning Pin Description
Package: DIP18 Pin Symbol Function
1 Output Trigger output
2 GND Ground181 VOutput sync
3 LED2 Display output Green”
GND 2 17 4 V Phase angle control input voltageiC
5 OP Operational amplifier outputO
LED2 3 16 6 OP Operational amplifier inputR I
7 T Maximum temperaturemax
4 15V 8 Sensor Temperature sensori VS
9 t Charge break outputp
OP 5 14O V 10 V Battery voltageRef Batt
11 LED1 LED display output Red”
OP 6 13I Osc 12 S Test mode switch (status control)TM.
13 Osc Oscillator
Tmax 7 12 STM. 14 V Reference output voltageRef
15 V Supply voltageS
Sensor 118 LED1
16 Ramp current adjustment – R
tp 9 10 V 17 Ramp voltage – capacitanceBatt C
93 7723 e
18 V Mains synchronization inputsync.
Package: SO20 Pin Symbol Function
1 Output Trigger output
20 2 GND Ground1 VOutput sync
3 LED2 Display output Green”
19GND 2 4 V Phase angle control input voltageC i
5 OP Operational amplifier outputO
LED2 3 18 6 OP Operational amplifier inputR I
7 NC Not connected
V V4 17i S 8 T Maximum temperaturemax
9 Sensor Temperature sensor
5 16 NCOP 10 t Charge break outputO p
11 V Battery voltageBatt
6 15 VOP RefI 12 LED1 LED display output Red”
13 S Test mode switch (status control)TM.
OscNC 7 14 14 Osc Oscillator
15 V Reference output voltageRef
T 13 S8 TM.max 16 NC Not connected
17 V Supply voltageS
9 12 LED1Sensor
18 Ramp current adjustment – R
t 10 11 Vp Batt 19 Ramp voltage – capacitanceC
20 V Mains synchronization input94 8594 sync.
2 (17) TELEFUNKEN Semiconductors
Rev. A3, 14-Nov-96
Figure 2. Block diagram with external circuit (DIP pinning)
TELEFUNKEN Semiconductors 3 (17)
Rev. A3, 14-Nov-96
100 k
1 k
From Pin 15
0.1 F
R / R
BC 308 T1
R 10 T2 V
1 k
R 560 k
10 k D D
D Th1 R
13 0.22 F 7 8
2 10
R 10 nF Red
2x 0
3 3
270 k
D C 0
R 2.2 k 10 nF
7 17 16 14 13 12 11
R 18
1 k
10 k
6.5 V/10 mA
Phase control
To Pin 4
Scan path
Control unit
Trigger output
B2 B1
V = 5 V
C C 10
10 k 1 k
S 15
V/dt & –dV
Power supply
V Monitor
I Batt
4.7 F ch 2
V = 8 to 26 V
470 F
0.1 to 4 V
16 k
160 mV
Temp. control
Power on
Ref Charge break
control output
max Sensor
(4 cells)
5 6 7 8 9
1 F 1 F
R 12 k
To V (Pin 14)
160 mV
6 T3 R
24 k
10 k 8 100 k
0.1 F
94 8674U2402B
General Description
The integrated circuit, U2402B, is designed for charging charge current or with NiMH batteries where weaker
Nickel-Cadmium (NiCd) and Nickel-Metal-Hydride charge characteristics are present multiple gradient con-
(NiMH) batteries. Fast charging results in voltage lobes trol results in very efficient switch-off.
when fully charged (figure 3). It supplies two identifica-
2 2 An additional temperature control input increases nottions (i.e., + d V/dt , and – V) to end the charge
only the performances of the charge switching character-operation at the proper time.
istics but also prevents the general charging of a battery
As compared to the existing charge concepts where the whose temperature is outside the specified window.
charge is terminated after voltage lobes according
A constant charge current is necessary for continuedto – V and temperature gradient identification, the
charge-voltage characteristic. This constant current regu-U2402B-C takes into consideration the additional
lation is achieved with the help of internal amplifier phasechanges in positive charge curves, according to the se-
control and a simple shunt-current control technique.cond derivative of the voltage with respect to time
2 2(d V/dt ). The charge identification is the sure method of
All functions relating to battery management can be
switching off the fast charge before overcharging the bat-
achieved with DC-supply charge systems. A DC-DC-
tery. This helps to give the battery a long life by hindering
converter or linear regulator should take over the function
any marked increase in cell pressure and temperature.
of power supply. For further information please refer to
Even in critical charge applications, such as a reduced the applications.
Battery insertion
5 V
Gradient recognition
2d V
Battery – V
2d V– V, , active
– V
monitoring shorted batteries ignored
95 10172 Fast charge rate IO
Top off Trickle
charge rate charge rate
1/4 I 1/256 IO O
t = 5 min t 20 min1 2
Figure 3. Charge function diagram, f = 800 Hzosc
4 (17) TELEFUNKEN Semiconductors
Rev. A3, 14-Nov-96
Flow Chart Explanation, f = 800 Hzosc
(Figures 2, 3 and 4)
Battery pack insertion disables the voltage lock at battery Top-Off Charge Stage
detection input Pin 10. All functions in the integrated
2 2circuit are reset. For further description, DIP-pinning is By charge disconnection through the +d V/dt mode, the
taken into consideration. device switches automatically to a defined protective
top-off charge with a pulse rate of 1/4 I (pulse time,O
t = 5.12 s, period, T = 20.48 s).p
Battery Insertion and –dV Monitoring
The top-off charge time is specified for a time of
20 minutes @ 800 Hz.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, Trickle Charge Stage
if positive, the defined fast charge rate, I , begins for theO
first 5 minutes according to –dV monitoring. After
When top-off charge is terminated, the device switches
5 minutes of charging, the first identification control is automatically to trickle charge with 1/256 I (t = 5.12 s,O p
executed. period = 1310.72 s). The trickle continues until the
battery pack is removed.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”. Basic Description
Voltage and temperature measurements across the battery
are carried out during charge break interval (see figure 6), Power Supply, Figure 2
i.e., currentless or idle measurements.
The charge controller allows the direct power supply of
If the inserted battery is fully charged, the –dV control 8 to 26 V at Pin 15. Internal regulation limits higher input
will signal a charge stop after six measurements voltages. Series resistance, R , regulates the supply1
(approximately 110 seconds). All the above mentioned current, I , to a maximum value of 25 mA. SeriesS
functions are recognised during the first 5 minutes resistance is recommended to suppress the noise signal,
2 2according to –dV method. During this time, +d V/dt even below 26 V limitation. It is calculated as follows:
remains inactive. In this way the battery is protected from
V –26 Vunnecessary damage. max
25 mA
V –8V2 2 mind V/dt -Gradient R1max Itot
If there is no charge stop within the first 5 minutes after
where2 2battery insertion, then d V/dt monitoring will be active.
In this actual charge stage, all stop-charge criteria are I = I + I + Itot S RB1 1
V V = Rectified voltagemax, min
I = Current consumption (IC) without loadSWhen close to the battery’s capacity limit, the battery
2 2voltage curve will typically rise. As long as the +d V/dt I = Current through resistance, RRB1 B1
stop-charging criteria are met, the device will stop the fast
charge activities. I = Trigger current at Pin 11
TELEFUNKEN Semiconductors 5 (17)
Rev. A3, 14-Nov-96
turn on
Power on reset
LED2 on
Charge stop
Cell insertion
LED1 blinking
Cell yesno
inserted ?
*) Cell insertion reset
Cell in
Cell intemperature
yes noLED1 on permissiblerange ?
temperatureLED2 off
range ?
Charging starts withV Batt
-dV monitoring
no4 V
LED2 blinkingyes
– dV
switch offno yes
Cell yesno
inserted ?
*) Chargingyes no
time reaches
5 min. ?
2 2– dV and d V/dt
no monitoring begins
*) 70 mV > V < 5 VBatt Cellyes
inserted ?
Cell in
range ?
2– dV no 2d V/dt
disconnect ? disconnect ? no
yes yes
LED1 on
LED2 on
LED2 on
Top-off charging
Trickle charging with 1/4 IO
with 1/256 IO
Cellyes yes
inserted ? Timer 20 min exceeded
93 7696 e no
Figure 4. Flow chart
6 (17) TELEFUNKEN Semiconductors
Rev. A3, 14-Nov-96
Value of the resistance, R is calculated by assumingB3Battery Voltage Measurement
R = 1 k , R = 10 k , as follows:B1 B2
The battery voltage measurement at Pin 10
(ADC-converter) has a range of 0 V to 4 V, which means V10maxR RB3 B2a battery pack containing two cells can be connected V –VBmax 10max
without a voltage divider.
The minimum supply voltage, V , is calculated forIf the AD converter is overloaded (V 4 V) a safety sminBatt
reset function after removing the inserted batteryswitch off occurs. The fast charge cycle is terminated by
according to:automatically changing to the trickle charge.
Precaution should be taken that under specified charge
0.03mA R R R 5V R R RB3 B1 B2 B1 B2 B3Vcurrent conditions, the final voltage at the input of the smin RB3
converter, Pin 10, should not exceed the threshold voltage
level of the reset comparator, which is 5 V. When the
where:battery is removed, the input (Pin 10) is terminated across
the pulled-up resistance, R to the value ofB1,
V = Max voltage at Pin 1010max5 V-reset-threshold. In this way, the start of a new charge
V = Min supply voltage at the IC (Pin 15)Sminsequence is guaranteed when a battery is reinserted.
V = Max battery voltageBmax
If the battery voltage exceeds the converter range of 4 V,
adjusting it by the external voltage divider resistance, R The voltage conditions mentioned above are measuredB2
and R is recommended. during charge current break (switch-off condition).B3
15 VS
- dV Recognition
RB1 –
V =Ref
I =ch 12 mV
DAC controlVDAC
comparatorRB2 VV BattB Battery –
ResetR Rsh B3
7 V V = –Ref
4.3 V +
95 10174 V = 0.1 VRef
Figure 5. Input configuration for the battery voltage measurement
Table 1. valid when V = 3.5 V10max
Cell No. 1 2 3 4 5 6 7 8 9 10 11 12
V (V) 8 8 8 9 11 13 15 17 19 21 23 25Smin
R (k – – 51 16 10 7.5 5.6 4.7 3.9 3.3 3 2.7B3
TELEFUNKEN Semiconductors 7 (17)
Rev. A3, 14-Nov-96
Analog-Digital-Converter (ADC), Plausibility for Charge Break
Test Sequence There are two criterian considered for charge break
A special analog-digital-converter consists of a five-bit
– V Cut-Offcoarse and a five-bit fine converter . It operates by a linear
count method which can digitalize a battery voltage of When the signal at Pin 10 of the DA converter is 12 mV
4 V at Pin 10 in 6.5 mV steps of sensitivity.
below the actual value, the comparator identifies it as a
voltage drop of – dV. The validity of – dV cutt-off is
In a duty cycle, T, of 20.48 s, the converter executes the
considered only if the actual value is below 12 mV for
measurement from a standard oscillation frequency of
three consective cycles of measurement.
f = 800 Hz. The voltage measurement is during theosc
2 2charge break time of 2.56 s (see figure 6), i.e., no-load d V/dt Cut-Off
voltage (or currentless phase). Therefore it has optimum
A four bit forward/ backward counter is used to registermeasurement accuracy because all interferences are
2 2the slope change (d V/dt , V – slope). This counter isBattcut-off during this period (e.g., terminal resistances or
clocked by each tracking phase of the fine AD-counter.dynamic load current fluctuations).
Beginning from its initial value, the counter counts the
first eight cycles in forward direction and the next eightAfter a delay of 1.28 s the actual measurement phase of
cycles in reverse direction. At the end of 16 cycles, the1.28 s follows. During this idle interval of cut-off
actual value is compared with the initial value. If there isconditions, battery voltage is stabilized and hence
a difference of more than two LSB-bit (13.5 mV) from themeasurement is possible.
actual counter value, then there is an identification of
An output pulse of 10 ms appears at Pin 9 during charge slope change which leads to normal charge cut-off. A
break after a delay of 40 ms. The output signal can be used second counter in the same configuration is operating in
in a variety of way, e.g., synchronising the test control parallel with eight clock cycles delay, to reduce the total
(reference measurement). cut-off delay, from 16 test cycles to eight test cycles.
94 8693
Charge break Charge
t2.56 s
T= 20.48 s
t10 ms
40 ms
t1.28 s 1.28 s
Figure 6. Operating sequence of voltage measurements
8 (17) TELEFUNKEN Semiconductors
Rev. A3, 14-Nov-96
Temperature Control, Figure 7
When the battery temperature is not inside the specified specified by the internal reference voltage of 4 V, and the
temperature windows, the overal temperature control will lower voltage transition is represented by the external
not allow the charge process. Sensor short circuit or voltage divider resistances R and R .T2 T3
interruption also leads to switch-off.
NTC sensors are normally used to control the temperature
Differentiation is made whether the battery exceeds the of the battery pack. If the resistance values of NTC are
maximum allowable temperature, T , during themax known for maximum and minimum conditions of
charge phase or the battery temperature is outside the allowable temperature, then other resistance values, R ,T1
temperature window range before battery connection. R and R are calculated as follows:T2 T3
A permanent switch-off follows after a measurement
suppose R = 100 k , thenT2period of 20.48 s, if the temperature exceeds a specified
level, which is denoted by a status of a red LED . A charge1 V –4VRef
R Rsequence will start only when the specified window T1 NTCmax 4V
temperature range is attained. In such a case, the green
RT2LED starts blinking immediately showing a quasi charge2 R RT3 NTCmin RT1readiness, even though there is no charge current flow.
The temperature window is specified between two If NTC sensors are not used, then select the circuit
voltage transitions. The upper voltage transition is configuration according to figure 10.
+ High
7 V
V = 4 VRef
+ Low
Sensor – temperature
7 V
94 8682
Figure 7. Temperature window
TELEFUNKEN Semiconductors 9 (17)
Rev. A3, 14-Nov-96
Current Regulation Via Phase Control (Figure 8)
Phase Control Charge Current Regulation (Figure 2)
An internal phase control monitors the angle of current According to figure 2 the operational amplifier (OpAmp)
flow through the external thyristors as shown in figure 2. regulates the charge current, I (= 160 mV / R ),ch sh
The phase control block represents a ramp generator average value. The OpAmp detects the voltage drop
synchronized by mains zero cross over and a comparator. across the shunt resistor (R ) at input Pin 6 as an actualsh
value. The actual value will then be compared with an
The comparator will isolate the trigger output, Pin 1, until
internal reference value (rated value of 160 mV).
the end of the half wave (figure 8) when the ramp voltage,
V reaches the control voltage level, V within a The regulator’s output signal, V is at the same time theramp, i, 5,
mains half wave. control signal of the phase control, V (Pin 4). In thei
adjusted state, the OpAmp regulates the current flow
angle through the phase control until the average value at
the shunt resistor reaches the rated value of 160 mV.
The corresponding evaluation of capacitor C at theR
operational amplifier (regulator) output determines the
dynamic performance of current regulation.
f = 50 HzmainsVsync
(Pin 18)
zero pulse
(Pin 17
) 6V
V i V i V i
(Pin 1)
0ms 10ms 20ms 30ms
93 7697 e
Current flow angle
Figure 8. Phase control function diagram
10 (17) TELEFUNKEN Semiconductors
Rev. A3, 14-Nov-96