U2482B [ETC]
Automotive Lamp Outage Monitor; 汽车灯故障监测
| 型号： | U2482B |
| 厂家： | 
ETC |
| 描述： | Automotive Lamp Outage Monitor |
| 文件： | 总11页 (文件大小：153K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
U2481B/ U2482B
TELEFUNKEN Semiconductors
Automotive Lamp Outage Monitor
Description
The U2481B and the U2482B multicomparator circuits With
are designed to monitor automotive illumination by
–
–
–
4 single comparators
1 double comparator and
2 triple comparators
sensing the voltage drop across shunt resistors. Provided
with extremely low comparator thresholds, these ICs can
be used together as a chip set to build an entire lamp
monitor system. Single operation of both circuits is also
possible.
each of the integrated circuits monitors up to 12 lamps
and up to 6 fuses.
As a special feature for brake lamp monitoring, the
U2481B contains a latch stage connected to one of its
triple comparators.
All comparator stages are combined together to control
the common output stage.
Features
Benefits
D Extremely low comparator thresholds of typically
D Extremely low threshold voltage gives low voltage
drop via shunt resistor. Power dissipation of the lamp
monitor module is minimized
3.5 mV
D Internal compensation for copper shunts
D Perfect EMC in conjunction with an appropriate
D Internal compensation for voltage-dependent
pc board layout
bulb characteristic
D Comparator input voltage may exceed supply voltage
D Internal protection measures for pulses
according to ISO TR 7637/1
D ESD according to MIL-SID-883 C test method 3015.7
– Human body model:
– Machine model:
4 kV
200 V
EMI protection (TEM cell up to 100 V/m)
Applications
Both ICs can be used in any kind of vehicle with a 12 V cluster with a pilot lamp. These ICs increase the safety
supply. It is sufficient to insert small resistors into the and add comfort features.
lamp wiring and to provide the dashboard instrument
Rev. A1: 21.08.1995
1 (11)
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
Block Diagram
V
B
20
19
V
V
Ref
28
S
B
REF
IN
K1
K1
13 mV
V
E1
S
27
Voltage drift
of comparator
threshold
Power
Stabilized
voltage
+
–
1K1
on
Reset
V
= 5.2 V
stab
I
T
I
T
= f (V )
B
I
T
POR
I
T
Divider
15
Oscillator
OSC
Clock 2
1
2
Clock 1
Ref K2
REF
13 mV
K2
20-T
2-T
Osc
Osc
IN
E1
1K2
Cl
2
Cl
1
7
6
8
9
Ref K3
E1
REF
K3
1K3
2K3
3.5 mV
IN
IN
Up down counter
T = 1.2 s
Cl
Cl
2
E2
V
S
Start
High at
Set
forward counter end
E3
IN
3K3
Out
High at
counter zero
Start
return
26
Reset
IN
FK3
1
24
25
3.5 mV
REF
Ref K4
E1
K4
14
17
IN
1K4
OUT
16
IN
FK5
4
3
5
REF
IN
Ref K5
E1
K5
3.5 mV
POR
Out
Reset
IN
FK6
1K5
2K5
Latch for
stoplamps
E2
IN
V
Set
B
22
21
K6 Ref
E1
REF
+
–
K6
23
IN
F
3.5 mV
IN
1K6
V
Up down counter
T = 1.2 s
S
Cl
2
* Connection to
GND only for
U2482B (latch
disabled
11
10
12
13
3.5 mV
REF
IN
Ref K7
E1
High at
Start
K7
counter end
forward
1K7
18
Start
return
High at
counter zero
GND
E2
IN
IN
2K7
3K7
*
Cl
1
E3
94 8833
Figure 1.
2 (11)
Rev. A1: 21.08.1995
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
Pin Description
Pin
1
Symbol
Function
Reference for threshold voltage
single comparator K2
REF
K2
1
REF
28 REF
K1
K2
2
3
4
IN
IN
REF
Input 1; single comparator K2
Input 1; double comparator K5
Reference for threshold voltage;
double comparator K5
1K2
1K5
27
IN
IN
2
1K2
1K1
K5
5
6
7
IN
IN
REF
Input 2; double comparator K5
Input 1; triple comparator K3
Reference for threshold voltage;
triple comparator K3
Input 2; triple comparator K3
Input 3; triple comparator K3
Input 1; triple comparator K7
(U2481B with latch)
Reference for threshold voltage;
triple comparator K7
(U2481B with latch)
Input 2; triple comparator K7
(U2481B with latch)
Input 3; triple comparator K7
(U2481B with latch)
Output for pilot lamp
R/C combination for oscillator
Fuse monitor input ; double
comparator K5
Fuse monitor input; single
comparator K6
Ground
Supply voltage
Reference voltage of compara-
tors
Input1; single comparator K6
Reference for threshold voltage;
single comparator K6
Input; brake fuse comparator
Reference for threshold voltage;
single comparator K4
Input 1; single comparator K4
Fuse monitor input; triple
comparator K3
Input 1; single comparator K1
Reference for threshold voltage;
single comparator K1
2K5
In
26
25
24
23
22
21
20
19
18
17
16
3
4
5
6
7
8
1K5
IN
FK3
1K3
K3
REF
IN
K5
2K5
1K3
1K4
8
9
10
IN
IN
IN
2K3
3K3
1K7
IN
IN
REF
K4
11
REF
K7
IN
F
12
13
IN
IN
2K7
REF
IN
REF
K3
K6
3K7
14
15
16
OUT
OSC
IN
2K3
1K6
IN
FK5
IN
9
V
V
3K3
1K7
17
IN
B
FK6
18
19
20
GND
V
V
10
11
12
13
14
IN
S
S
B
REF
GND
21
22
IN
K7
1K6
REF
K6
K4
IN
IN
23
24
IN
REF
2K7
FK6
F
IN
25
26
IN
IN
IN
3K7
1K4
FK3
FK5
27
28
IN
OUT
15
1K1
OSC
REF
K1
94 8831
Figure 2. Pin configuration
Rev. A1: 21.08.1995
3 (11)
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
150 W
R
1
1000 W
R
2
V
Batt
C
2
C
1
0.1 mF
15 mF
V
B
V
S
R
osc
20
19
82 kW
28
Osc
1 kW
2 kW
15
A
C
Fuse
osc
27
10 nF
Pilot
lamp
1.2 W
U2481B
U2482B
2 kW
16
4
Kl 61
Out
14
1 kW
2 kW
2 kW
Shunt
Shunt
3
5
B
95 10689
Out
A: Example of a “single comparator” using the fuse as a shunt resistor
B: Example of a “double comparator” using copper shunts and additional fuse monitoring
Figure 3. Basic application diagram
4 (11)
Rev. A1: 21.08.1995
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
Functional Description
A bulb is detected as “good” as long as the voltage drop
via the shunt resistor exceeds the threshold voltage. The
pilot lamp is off. A failed bulb is detected if the voltage
drop via the shunt resistor is smaller than the threshold
voltage. The pilot lamp is on. An external transistor is
necessary to drive the pilot lamp.
Power Supply, Pins 19 and 20
The Ics have two supply pins. The IC itself is supplied via
Pin 19 (stabilized voltage, POR-circuitry). Pin 20
supplies only the current sources of the comparators. Both
pins have an an internal 21 V Zener Diode for protection.
For reasons of interference protection and surge
immunity the supply voltage pins have to be provided
with RC-circuitries as shown in figure... The resistors
limit the current in the case of overvoltage, whereas the
capacitors smooth the supply voltage.
In order to disable monitoring when the lamps are
switched off, therefore the comparator outputs are
disabled if the reference voltage V < V
with
ref
Min
V
Min
= 0.33 V .
B
As protection against transients on the supply, all
comparator inputs require external resistors. Their
tolerances directly influence the comparator threshold
Recommended values:
Pin 19:
Pin 20:
R = 150 W; K = 0.1 mF
R = 1000 W; K = 0.1 mF
accuracy. Resistors with
recommended.
a " 1% tolerance are
An external diode protects the IC against battery reversal.
Single comparators: The inputs (K1, K2, K4, K6) sink
currents of typically 10 mA each. During switch-over, the
currents of reference and input pins are identical.
Therefore identical external protection resistors
(R = 1 kW) are required.
Power-On-Reset
When the supply voltage is switched on, a power-on-reset
pulse is generated internally which resets the brake lamp
monitor latch and the counter stages.
Double comparator: The reference input (K5) sinks a
current of typically 20 mA; its inputs sink currents of
typically 10 mA each during switch-over. Therefore the
external protection resistors must provide R = 1 kW for
Oscillator, Pin 15
The RC-oscillator is the time base for clock 1 and clock 2
(see block diagram) which are desired from a divider
stage and fed to the two upward and downward counters.
REF and R = 2 kW each for IN
and IN
.
K5
1K5
2K5
Triple comparators: The reference inputs (K3 and K7)
sink currents of typically 30 mA. All inputs (IN , IN
The oscillator frequency f is mainly determined by the
osc
external R/C components and an integrated resistor. The
capacitor K is charged by the external resistor and
discharged by the integrated one. Because of the temper-
ature characteristic and the tolerances of the integrated
2 kW-resistor, the external one has to have considerable
higher value in order to achieve a stable frequency.
1K3
2K3
IN
and IN , IN , IN ) sink the identical typical
3K3,
1K7 2K7 3K7
current of 10 mA during switch-over. Therefore the
external protection resistor must provide R = 1 kW for
REF and REF and R = 3 kW at each input.
K3
K7
Fuse Monitoring
Calculation of the frequency:
The internal EXOR conjunction of comparators K1 and
K2 allows fuse monitoring for both lamps. Even a
simultaneous blowout of both fuses is detected.
1
fosc
1
fosc
+
+
(0.74 Rosc ) 2260 W)
cosc
With the recommended values
= 82 kW and C = 10 nF
The pins IN , IN
can be used for additional fuse monitoring.
and IN
with their EXOR gates
FK3
FK5
FK6
R
osc
osc
Detection threshold for a blown fuse is V < V
with
Min
ref
f
≈ 1.58 kHz
osc
V
Min
= 0.33 V (V = reference voltage of comparators).
B B
Comparators
Pin IN is used for brake fuse monitoring. With a voltage
F
drop V > 4.8 V across the fuse, the comparator detects
Comparators K1 and K2: threshold voltage of typically
F
a blown fuse. A voltage drop V < 2.8 V represents a
V
th
= 13 mV; designed to monitor high- and low-beam
F
“good” fuse. U2481B’s comparator K7 is connected to a
latch, thus a brake lamp outage is memorized.
bulbs, where the fuses can be used as shunt resistors.
Comparators K3 to K7: threshold voltage of typically
V = 3.5 mV; designed for all other monitor purposes.
th
Due to the integrated compensation circuitry, these
comparators are suitable for pc layer copper shunts.
Rev. A1: 21.08.1995
5 (11)
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
Latch for Brake Lamp Monitor
Integrated Delay, Debouncing, Failure Dis-
play
A failure of a brake lamp detected by comparator K7 or
a blown fuse in the brake circuitry is memorized after the
delay time has expired.
As soon as a comparator detects a failure a slow upward
counter is started in order to generate the delay time,
t
= 1.2 s. With a consistent failure the output stage is
del
A reset of the latch can only be performed with a “power-
on-reset”.
enabled after t . If the failure disappears during t a fast
downward counter is started in order to generate the reset
time t y 135 ms. The upward counter is reset, the
del
del
Output Stage
reset
output stage stays disabled.
The output is a Darlington stage stage with protection
diodes to V and IC ground. The output is designed to
drive an external pilot lamp with an external PNP
transistor.
Benefits: Intermittent contacts in the wire harness do not
activate the pilot lamp! Even cyclical intermittent
contacts are screened out as long as the pulse/pause ratio
is smaller than 10:1. In the case of higher duty cycles the
upward counter may reach its trigger threshold for the
S
At the end of the delay time the output stage is switched
on and can source a current of I = –10 mA with a typical
out
output activation after t > t
.
del
saturation voltage of V = 1 V.
sat
Individual delay- and reset times can be adjusted with
external R/C components according to (see “oscillator”)
Test Mode
With V
= 23 V (20 mA) applied to Pin osc, via a
TEST
–
–
t
t
= 1930 x t
del
osc
osc
200 W resistor the delay time stage can be bypassed for
test purposes. A failure detection will be displayed
immediately to save time during threshold testing.
= 198 x t
reset
6 (11)
Rev. A1: 21.08.1995
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
Application Hints
Two equations for calculation of the shunt resistance:
Layout Recommendations for Copper
Layer Shunts
R
shunt
= R <L/W
A cn
(with R = Cu sheet resistance)
A
Lamp outage monitor systems can be produced most cost-
efficiently if stamped shunt resistors are replaced by
copper layer shunts which are generated with the pc board
layout.
R
= V / 1/2 I
shunt
Th LAMP
Thus the length of copper shunt is calculated as:
L = 2<V / R
W
Th< cn
I
A< LAMP
L = 215 mm
The U2481B and the U2482B are suitable for this
application because of their comparator thresholds,
which are compensated in reference to the temperature
characteristic of copper.
For a reasonable pc-layout a meander-shaped shunt
resistor is recommended. The high lamp currents may
cause hot spots at sharp edges of the copper shunts. That
may deteriorate accuracy of the measurement. Therefore
it is recommended to layout the copper shunts with
smoothed curves.
A constant lamp current, I
= V /R with threshold
Th sh
LAMP
voltage V = f(T) and shunt resistor R = f(T), is
Th
sh
achieved if the comparator threshold and the shunt
In accordance to figure...the meander may be formed by
resistor have identical temperature characteristics. With
4 straight tracks (length L each) and 3 connecting 180°
–3
S
the temperature coefficient of copper a = 3.9<10
cu
ares (length L are each). If the mean are radius is selected
1/K, a copper shunt changes its nominal value by 52% if
to r = W the are lenght becomes L = p W .
cn
are
cn
the automotive ambient temperature range of t
= –40
amb
to +95°C is taken into consideration.
Thus the total lenght is
Examples for sheet resistances of copper shunts
(T = 25°C):
R = 0.5 mW/square (35.1 mm layer thickness)
A
L = 4 L + 3 L
S
are
amb
= 4 L + 3 p W
S
cn
R = 0.25 mW/square (70 mm layer thickness)
A
With L = 215 mm the track length becomes
1
How to Lay Out Copper Shunts (figure 3)
LS + (L * 3 p Wcn)
4
The width of the copper trace has to be selected in
reference to a low current-effected temperature increase.
L = 47.8 mm
S
Using Fuses as Shunt Resistors
The copper trace must be capable of peak currents which
do not blow the fuse. The peak currents are specified by
the car manufacturers.
This cost saving method can be used if the following
assumptions are fulfilled:
Example:
–
–
Each lamp needs a dedicated fuse
A 7.5 A fuse allows a peak current of 26 A (1 s), 15 A
(10 s) or 10 A (60 s).
The fuse socket is mounted within the monitor
module to connect the sense linesare suitable for
this monitor
The copper shunt length has to be calculated between the
two sense connections to the comparator. The connection
of the common reference input of double and triple
comparators has to be considered carefully.
–
task because of their comparator thresholds are
compensated for the fuse temperature coefficient
–3
of a = 4.1<10 1/K
F
Calculation example for a copper shunt used with a 4 W
bulb.
Calculation Example for a 55 W Bulb and a
7.5 A fuse:
I
= 0.325 A
LAMP
Measured voltage drop across the fuse: V = 52 mV
F
Failure criterion: I = 1/2<I
10 A fuse is capable of I = 13.5 A
Copper layer thickness: 70 mm
Comparator threshold voltage (U2481B, U2482B):
LAMP
Measured current: I
= 4.2 A
LAMP
Calculated resistance: R = 12.4 mW
F
Selected comparatore threshold:
V
Th
= 1/4 V = 13 mV (typically);
F
V
= 3.5 mV
Th
With a lamp current I
< V /R =< 1.05 A
Th F
LAMP
the comparator detects a blown fuse.
Assumed copper width for temperature increase
DT < 50°C:
cu
W
cu
= 2.5 mm (13.5 A, 70 mm)
Rev. A1: 21.08.1995
7 (11)
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
W
cn
= 2.5 mm
to lamp
to lamp switch
L
S
L
arc
W
cn
R2
R1
26
16
13
28
27
25
24
22
19
10
18
17
12
15
14
23
21
20
U2481B
U2482B
5
9
1
2
3
4
8
6
7
11
Figure 4. Design example for a copper shunt with meander shape
Absolute Maximum Ratings
Parameters
Supply voltage
Pulse current (2 ms)
Symbol
V , V
Value
16.5
1.1
Unit
V
A
S
Batt
I
S
Short circuit current (reversed battery)
Output current
Junction temperature
I
I
T
j
170
–12
150
mA
mA
°C
SC
out
Thermal Resistance
Parameters
Thermal resistance
Ambient temperature range
Storage temperature range
Symbol
R
thJA
Value
110
–40 to +100
–55 to +125
Unit
K/W
°C
SO 28
T
amb
T
stg
°C
8 (11)
Rev. A1: 21.08.1995
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
Electrical Characteristics
T
= –40 to +100_C, V
(Kl. 15) = 10 to 15 V, supply series resistors and input protection rsistors connected (see
amb
Batt
figure 1 “block diagram” and figure 2 “basic application schematic”) unless otherwise specified.
Parameters
Test Conditions / Pins
Symbol
Min.
9
Typ.
Max.
16
Unit
V
Supply
Operating voltage
Supply current
V
Batt
V
= 13 V, V = low
14
Batt
Pin 20
Pin 19
0.3
3
0.7
5
1.1
7
mA
mA
Power on reset (POR)
T
V
= 25°C
(Kl. 15)
Pin 19
3.0
3.7
4.2
5.0
V
V
amb
Batt
Comparators
Comparator input current
during switch over
V
Batt
= 13 V Pins 27, 28
Pins 1, 2
I , I
I , I
1
10
10
27 28
2
Pins 24, 25
Pins 21, 22
Pin 7
I , I
10
10
30
24 25
I , I
21 22
I
mA
7
Pins 6, 8, 9
Pin 11
I , I , I
10
30
6
8
9
I
11
Pins 10–12 I10,I11,I12
10
Pin 4
I
20
4
Pins 3,5
I , I
3
10
5
Comparator thresholds V
V = 10 V Pins 1, 2, 27, 28
8.5
10.0
11.0
11.5
13.0
14.0
14.5
16.0
17.0
T1
S
of comparators K1 and K2
(V = V – V
V = 13 V
V
mV
S
T1x
)
V = 15 V
S
T1
Ref...
IN...
x = Pin No.
Voltage characteristic
Temperature characteristic
DV
DT
0.5
3900
mV/V
ppm/°K
T1
T1
Comparator thresholds V
of comparators K3 to K7
Pins 6, 7, 8, 9
Pins 24, 25
T2
(V = V
– V )
Pins 3, 4, 5
T2
Ref...
IN...
Pins 21, 22
Pins 10, 11, 12
V = 10 V
V
1.5
2.0
2.3
3.0
3.5
3.8
4.5
5.0
5.3
S
T1x
V = 13 V
mV
S
x = Pin No.
V = 15 V
S
Voltage characteristic
Temperature characteristic
DV
0.17
3900
mV/V
ppm/°K
T2
DT
T2
Min. comparator input
voltage for detection
all Ref-pins
V
Min
0.33
V
Batt
Output
Output current
Output saturation voltage
V
= 13 V
= –10 mA
Pin 14
I
V
–10.0
1.0
mA
V
Batt
14
I
1.5
out
Sat
Pin 19–Pin 14
Rev. A1: 21.08.1995
9 (11)
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
Parameters
Protection
Voltage of Zener diodes
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
V
Pin 19
Pin 20
V
S
21
19
V
B
all Ref... and IN... pins
V
Ref...
,
V
IN...
19
Oscillator
Oscillator frequency
R
osc
C
osc
= 82 kW,
= 10 nF,
f
1.58
kHz
osc
Pin 15
Delay time
R
osc
C
osc
= 82 kW,
= 10 nF
t
d
1.1
1.2
1.3
s
Debounce time
R
osc
C
osc
= 82 kW,
= 10 nF
t
db
115
125
135
ms
Break fuse
Brake fuse detection
threshold
Input current
V
V
Pin 23
V
2.8
3.8
4.8
V
Batt
TB
= 13 V
Pin 23
I
100
mA
23
23
Trigger threshold (internal
pull down resistor)
Pins 16, 17, 28
V
0.33
V
TTx
V
Batt
x=16,17,18
Input current
V
Batt
= 13 V
I
100
mA
Test
Test voltage for delay time
override
I = 20 mA
Pin 15
V
15
23
V
Dimensions in mm
Package: SO 28
95 9932
10 (11)
Rev. A1: 21.08.1995
Preliminary Information
U2481B/ U2482B
TELEFUNKEN Semiconductors
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TEMIC can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain
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Parameters can vary in different applications. All operating parameters must be validated for each customer
application by the customer. Should the buyer use TEMIC products for any unintended or unauthorized
application, the buyer shall indemnify TEMIC against all claims, costs, damages, and expenses, arising out of,
directly or indirectly, any claim of personal damage, injury or death associated with such unintended or
unauthorized use.
TEMIC TELEFUNKEN microelectronic GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany
Telephone: 49 (0)7131 67 2831, Fax number: 49 (0)7131 67 2423
Rev. A1: 21.08.1995
11 (11)
Preliminary Information
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