U2480B
TELEFUNKEN Semiconductors
Rev. A1, 22-Oct-97
1 (8)
Automotive Lamp Outage Monitor
Description
The IC U2480B is designed for individual monitoring of
11 lamps in automobiles. Three double comparators and
five single comparators, which can be optionally inter-
connected, permit realization of many monitoring
variants. An integrated latch is available to memorize the
outage of indicator or brake lamps.
Features
D 10 mV comparator thresholds
D Temperature compensated
D Voltage characteristic of the lamps is taken into
account
D Input voltage range up to 23 V independent of supply
D Typical input currents 25 mA, so that protective
resistors can be connected in series
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:
4 kV
Machine model:
200 V
EMI protection (TEM cell up to 100 V/m)
Ordering Information
Extended Type Number
Package
Remarks
U2480B
SDIP28
Block Diagram
13945
5 single
comparators
Stabili
zation
3 double
comparators
Logic / Timing
Latch
Output
stage
Oscillator
GND
Pilot lamp
V
Batt
V
S
OSC
V
Stab
V
Stab
U2480B
TELEFUNKEN Semiconductors
Rev. A1, 22-Oct-97
2 (8)
Detailed Block Diagram
22 V
22 V
22 V
Voltage drift
of comparator
threshold
I
th
= f (V
S
)
Ref
E1
K2
I
th
Ref
E1
E2
K3
20
3
2
19
21
Ref
E1
K4
5
4
Ref
E1
K5
27
26
Ref
E1
K6
1
28
16
15
17
Set
Reset
Out
Clock 1
T
osc
x2
Clock 2
T
osc
x20
Divider
T1
T2
Oscillator
Stabilized
voltage
V
stab
= 5.5 V
Power-
on
reset
Ref
E1
E2
K7
23
22
24
Ref
E1
K8
7
8
Start
forward
Start
return
High at
counter end
High at
counter zero
Forward and return counter
T = 1.2 s
Start
forward
Start
return
High at
counter end
High at
counter zero
Forward and return counter
T = 1.2 s
Latch for indicator
and stop lamps
Reset
Out
Set
23 V
+
+
+
+
25 V
+
7 V
9
10
13
8
14
11
12
V
stab
V
S
Osc
V
out
BL
SP
Latched at
signal "low"
13910
7 V
T1
T2
K1
Figure 1. Block diagram
U2480B
TELEFUNKEN Semiconductors
Rev. A1, 22-Oct-97
3 (8)
Pin Description
13373
REFK6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
E1K2
RefK2
E1K4
REFK4
E1K8
REFK8
OSC
GND
V
S
BL
SP
V
stab
V
out
E1K6
REFK5
E1K5
NC
E2K7
REFK7
E1K7
E2K3
REFK3
E1K3
NC
E2K1
REFK1
E1K1
Figure 2. Pin configuration
Pin
Symbol
Function
1
REFK6
Reference for threshold voltage
single comparator K6
2
E1K2
Input 1; single comparator K2
3
REFK2
Reference for threshold voltage;
double comparator K5
4
E1K4
Input 1; single comparator K4
5
REFK4
Reference for threshold voltage;
double comparator K4
6
E1K8
Input 1; single comparator K8
7
REFK8
Reference for threshold voltage;
triple comparator K8
8
OSC
Oscillator input
9
GND
Ground
10
V
S
Supply voltage
11
BL
Input window comparator for
direction indicator
12
SP
Programming pin for memory
function
13
V
stab
Stabilized voltage
14
V
out
Output for tell-tale lamp
15
E1K1
Input 1; double comparator K1
16
REFK1
Reference for threshold voltage;
double comparator K1
17
E2K1
Input 2; double comparator K1
18
NC
Not connected
19
E1K3
Input 1; double comparator K3
20
REFK3
Reference for threshold voltage
double comparator 3
21
E2K3
Input 2; double comparator K2
22
E1K7
Reference for threshold voltage;
double comparator K7
23
REFK7
Reference for threshold voltage
double comparator 7
24
E2K7
Input 2; double comparator K7
25
NC
Not connected
26
E1K5
Input 1; single comparator K5
27
REFK5
Reference for threshold voltage
single comparator 5
28
E1K6
Input 1; single comparator K6
U2480B
TELEFUNKEN Semiconductors
Rev. A1, 22-Oct-97
4 (8)
Functional Description
Comparators
The voltage threshold of all internal comparators has a
typical value of V
th
= 10 mV.
A voltage drop accross the shunt of V
sh
wV
th
means no
fault in the lamp circuit and the output is disabled.
In the event of a voltage drop V
sh
vV
th
, the output sup-
plies the current I
O
, and the pilot lamp is activated by the
external transistor.
The output is reliably disabled for a voltage at the refer-
ence pin of the comparators of V
minRef
v 1/3 V
S
The typical values of the input currents are 25
mA and are
equally large at the switch-over instant, thus making it
possible to connect protective resistors in series. The
internal threshold is independent of the value of the
protective resistor as long as all resistors of a comparator
have the same value.
Fuse Monitoring
It is possible to monitor the fuses of the lamp circuits by
means of an EXCLUSIVE OR function between K1 and
K3 and between K5 and K6.
If the Ref pin of K1 (orK5) is low and the Ref pin of K2
(or K6) is simultaneously high, or vice versa, a fault is
indicated.
Simultaneous failure of both fuses is not detected.
A fuse is faulty if the input voltage at the pin Ref falls
below the voltage V
minRef
(1/3 V
S
).
Time Delay
A fault is indicated only if it is present for t
d
= 1.2
"0.2 s.
If an OK pulse
w100 ms occurs during this time, time
counting is reset to "0". An OK pulse is generated if the
comparators K1 to K8 and the input BL do not signal a
fault.
A periodic fault signal (period of less than 1 s) is indicated
only if the mark-to-space ratio is
w10/1, whereby the
pulse time corresponds to an item of fault information.
The time delay until the fault is indicated exceeds the time
t
d
= 1.2 s in this case.
Storage
A failure in the break light circuit which is present for
longer than t
d
is stored.
A voltage of V
BL
v 0.15 V
S
which is present at the input
BL for longer than t
d
leads to fault indication with
storage. This allows the possibility of additional flashing
monitoring.
A voltage of V
BL
w 0.2 V
S
and of V
BL
v 0.65 V
S
which
is present at the input BL for longer than t
d
leads to fault
indication without storage. It is thus possible to extend the
scope of monitoring beyond 11 lamps by means of
additional comparators ICs.
A voltage of V
BL
w 0.7 V
S
at the input BL does not cause
a fault signal.
The turn indicator and the brake light memory is
maintained by V
S
(terminal 15)
Power-on Reset
When V
Batt
(terminal 15) is applied to Pin V
S
, a brief
signal is produced which generates the power-on reset. As
a result, the turn indicator, the brake light memory and the
counters are reset.
Outputs
A fault signal at the comparators K1 to K8 or at the
comparator Pin BL enables the output so that current I
O
can flow. The output blocking voltage (V
S
V
out
) is
typically 1 V.
Threshold Testing without Time Delay t
d
To connect the input comparators directly to the output
pin, a voltage of 6 V at Pin OSC is necessary (omit R
OSC
and C
OSC
).
Absolute Maximum Ratings
Parameters
Symbol
Value
Unit
Supply voltage
V
S
, V
Batt
16.5
V
Pulse current (2 ms)
I
S
1.1
A
Short circuit current (reversed battery)
I
SC
170
mA
Output current
I
out
12
mA
Ambient temperature range
T
amb
40 to +100
C
U2480B
TELEFUNKEN Semiconductors
Rev. A1, 22-Oct-97
5 (8)
Unit
Value
Symbol
Parameters
Storage temperature range
T
stg
55 to +125
C
Junction temperature
T
j
150
C
Thermal Resistance
Parameters
Symbol
Value
Unit
Thermal resistance
SDIP 28
R
thJA
75
K/W
Electrical Characteristics
V
Batt
(Kl. 15) = 10 to 15 V, T
amb
= 40 to +95
_C, supply series resistors and input protection resistors connected (see
figure 1 "Block diagram" and figure 3 "Basic application schematic") unless otherwise specified.
Parameters
Test Conditions / Pins
Symbol
Min.
Typ.
Max.
Unit
Supply
Supply current
V
Batt
= 12 V, V
out
= low
I
S
6
mA
Power on reset (POR)
V
S
3.5
5.2
V
Comparators
Comparator input current
during switch over
V
Batt
= 12 V Pin 2
Pin 4
Pin 6
Pins 15, 16
Pins 19, 21
Pins 22, 24
Pin 26
Pin 28
I
K2
I
K4
I
K8
I
K11,
I
K12
I
K31,
I
K32
I
K71
,I
K72
I
K5
I
K6
25
mA
Comparator output current
V
Batt
= 12 V Pin 1
Pin 3
Pin 5
Pin 7
Pin 15
Pin 20
Pin 23
Pin 27
I
O6
I
O2
I
O4
I
O8
I
O1
I
O3
I
O7
I
O5
10
mA
Comparator thresholds
V
thx
= V
REFKx
V
ExKx
x = PinNo.
V
Batt
= 12 V
V
Batt
= 15 V
V
thx
V
thx
5.0
6.3
10.0
11.4
15.0
16.5
mV
mV
Minimum comparator input
voltage
V
minRef
0.33
V
S
V
Output V
out
Pin 14
Output current
V
S
= 12 V
I
14
10.0
mA
Output saturation voltage
V
sat
= V
S
V
out
I
out
= 10 mA
V
sat
1.5
V
Protection
Voltage of Zener diodes
all REFKx and ExKx. pins
Pin VS
Pin BL
Pin V
stab
and OSC
V
Z1
V
Z2
,
V
ZBL
V
Z3
22
23
25
7
V
V
V
V
Oscillator
Pin 8
Oscillator frequency
R
osc
= 82 k
W,
C
osc
= 10 nF,
f
osc
1.67
kHz
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