TELEFUNKEN Semiconductors
U 6046 B / U 6047 B
Rear window heating timer
Description
The window heating timers are bipolar integrated circuits.
Due to time controlled functions, they reduce the current
consumptions of high loads i.e., heating resistors. An
ON-relay can be switched off after a preset delay time. The
relay time can be interrupted manually whereas a retrigger
function is not provided.
Features
D
D
D
D
D
Delay time range: 3.7 s to 20 h
RC oscillator determines switching characteristics
Relay driver with Z-diode
Debounced input for toggle switch
Two debounced inputs: ON and OFF
D
D
D
D
D
Load dump protection
RF interference protected
Protection according to ISO/TR7637-1 (VDE 0839)
U 6046 B: Inputs switched to V
Batt
U 6047 B: Inputs switched to ground
Cases:
DIP 8
SO 8
U 6046 B, U 6047 B
U 6046 B–FP, U 6047 B–FP
C
2
R
2
6
V
stab
7
47
m
F
V
S
C
1
R
1
510
W
V
Batt
OSC
8
Oscillator
Stabilization
Power-on reset
Low dump detection
1
GND
Frequency divider
3
ON
4
OFF
5
TOGGLE
94 8747
Debouncing
Monoflop
Relay control
output
2
Figure 1 Block diagram with external circuit
Rev. A1: 22.09.1994
1
U 6046 B / U 6047 B
Pin Configuration
Pin
1
2
3
4
5
6
7
8
Symbol
GND
RELAY
ON
OFF
TOGGLE
OSC
V
stab
V
S
Function
Reference point, ground
Relay control output
Switch-on input
Switch-off input
Toggle input
RC oscillator input
Stabilized voltage
Supply voltage
GND
RELAY
1
TELEFUNKEN Semiconductors
8
V
S
V
stab
OSC
TOGGLE
2
7
ON
OFF
3
6
4
94 8844
5
Functional description
Power supply, Pin 8
For reasons of interference protection and surge immunity,
the supply voltage (Pin 8) must be provided with an
RC circuit as shown in figure 2a. Dropper resistor, R
1
,
limits the current in case of overvoltage, whereas C
1
smoothes the supply voltage at Pin 8.
Recommended values are: R
1
= 510
W
, C
1
= 47
m
F.
The integrated Z-diode (14 V) protects the supply
voltage,V
S
, therefore, the operation of the IC is possible
between 6 V and 16 V, supplied by V
Batt
.
However, it is possible to operate the integrated circuit with
a 5 V supply, but it should be free of interference voltages.
In this case, Pin 7 is connected to Pin 8 as shown in
figure 2b, and the R
1
C
1
circuit is omitted.
V
Batt
R
1
C
1
47
m
F/
16 V
510
W
R
2
C
2
C
2
V
S
= 5 V
R
2
8
7
6
8
5
V
Batt
7
6
5
1
1
2
3
4
2
3
4
94 8750
94 8749
Figure 2b Basic circuit for V
S
= 5 V
Figure 2a Basic circuit for 12 V supply and oscillator
2
Rev. A1: 22.09.1994
TELEFUNKEN Semiconductors
Oscillator, Pin 6
Oscillator frequency, f, is determined mainly by the
R
2
C
2
circuit. Resistance, R
2
, determines the charge time,
and the integrated resistance (2 k
W
) is responsible for
discharge time. For the stability of the oscillator frequency,
it is recommended that the selected R
2
value be much
greater than the internal resistance (2 k
W
), because the
temperature response and the tolerances of the integrated
resistance are considerably greater than the external
resistance value.
Oscillator frequency, f, is calculated as follows:
f
1
+
t
)
t
1
2
U 6046 B / U 6047 B
Relay control output
The relay control output is an open collector Darlington
circuit with an integrated 23-V Z-diode for limitation of the
inductive cut-off pulse of the relay coil. The maximum
static collector current must not exceed 300 mA and
saturation voltage is typically 1.1 V @ 200 mA.
Interference voltages and load dump
The lC supply is protected by R
1
, C
1
, and an integrated
Z-diode, while the inputs are protected by a series resistor,
integrated Z-diode and RF capacitor (refer to Figure 6).
The relay control output is protected via the integrated
23-V Z-diode in the case of short interference peaks. It is
switched to conductive condition for a battery voltage of
greater than approx. 40 V in the case of load dump. The
output transistor is dimensioned so that it can withstand the
current produced.
a
1
and
a
2
are constants as such
a
1
= 0.833 and
a
2
= 1.551 when C
2
= 470 pF to 10 nF
a
1
= 0.746 and
a
2
= 1.284 when C
2
= 10 nF to 4700 nF
Debounce time, t
3
, and the delay time, t
d
, depend on the
oscillator frequency, f, as follows:
t
3
t
d
where
t
1
= charge time =
a
1
R
2
C
2
t
2
= discharge time =
a
2
2 k
W
@ @
@
@
C
2
Power-on reset
When the operating voltage is switched on, an internal
power-on reset pulse (POR) is generated which sets the
logic of the circuits to a defined initial condition. The relay
output is disabled.
+
6
@
1
f
+
73728
@
1
f
Table 1 shows relationships between t
3
, t
d
, C
2
, R
2
and
frequencies from 1 Hz to 20 kHz.
V
Batt
R
1
C
1
47
m
F/
16 V
8
510
W
C
2
R
2
S1
20 k
W
6
5
V
Batt
R
1
C
1
47
m
F/
16 V
510
W
S1
C
2
R
2
2 k
W
6
7
8
7
5
U 6046 B
U 6047 B
4
1
2
3
1
94 8751
2
3
4
94 8752
Figure 3a TOGGLE function U 6046 B
Figure 3b TOGGLE function U 6047 B
Rev. A1: 22.09.1994
3
U 6046 B / U 6047 B
Relay control output behaviour, Pin 2
Time functions (relay output) can be started or interrupted
by the three inputs i.e., ON, OFF or TOGGLE (Pins 3, 4 and
5).
The relay becomes active if the time function is triggered,
and the relay contact is interrupted after the elapse of delay
time, t
d
. There are two input possibilities:
TELEFUNKEN Semiconductors
the switching of the Pin 4 switch correspondingly leads to
the relay being de-energized. If the relay is not
de-energized by the push-button switch, it becomes
disabled after the delay time, t
d
, is over.
Combined operation, “TOGGLE and ON/OFF” is not
possible due to the fact that there is only one debouncing
circuit. Debouncing functions on both sides i.e., whenever
S
1
is ON or OFF.
If Pin 3 (input ON) is continuously closed, the delay time,
t
d
, still elapses and the relay is interrupted. This can be used
to generate a defined power-on-reset pulse to trigger, for
example, a delay time, t
d
, when the battery voltage, V
Batt
,
is applied.
Figure 6a shows the input circuit of U 6046 B. It has an
integrated pull-down resistance (20 k
W
), RF capacitor
(15 pF) and Z-diode (7 V). It reacts to voltages greater than
2 V. The external protective resistor has a value of 20 k
W
and the push-button switch, S, is connected to the battery
as shown in the diagram.
Contact current, I, is calculated as follows:
I
I
V –V
+
R(
+
20 k
W
)
Batt
Z
Toggle input, figure 3 and 5A
When the push-button (TOGGLE) switch, S
1
, is pressed for
the first time, the relay becomes active after the debounce
time, t
3
, i.e., the relay output, Pin 2, is active.
Renewed operation of S
1
causes the interruption of the
relay contact and the relay is disabled. Each operation of
the toggle switch, S
1
, changes (alters) the condition of the
relay output when the debounce time, t
3
, is exceeded i.e.,
the TOGGLE function.
If the relay output is not disabled by pressing the switch S
1
,
the output is active until the delay time, t
d
, is over.
ON, OFF inputs, Pins 3 and 4,
figures 4 and 5B
To avoid simultaneous operation of both inputs, Pin 3 (ON)
and Pin 4 (OFF), use of two-way contact with centre-off
position with spring returns (also known as rocker-actuated
switch) is recommended.
Pressing the push-button switch (Pin 3-ON) leads to the
activation of the relay after the debounce time, t
3
, whereas
where V
Batt
+
12 V,
V
Z
+
7 V
+
(12–7)
W
V
[
0.25 mA
20 k
It can be increased by connecting a 5.6 k
W
resistor from the
push-button switch to ground as shown in figure 10a.
V
Batt
R
1
510
W
R
2
C
2
V
Batt
R
1
C
1
47
m
F/
16 V 8
S3
510
W
R
2
C
2
20 k
W
5
20 k
W
C
1
47
m
F/
16 V
8
7
6
5
7
6
U 6047 B
U 6046 B
1
1
2
3
4
2 k
W
94 8753
2
3
4
2 k
W
S3
94 8754
Figure 4a ON/OFF function U 6046 B
4
Figure 4b ON/OFF function U 6047 B
Rev. A1: 22.09.1994
TELEFUNKEN Semiconductors
Figure 6b shows the input circuit of U 6047 B. It has an
integrated pull-up resistance (100 k
W
), RF capacitor
(15 PF) and Z-diode (7 V). The circuit reacts to voltages
less than 2 V. The external protective resistance has a value
of 2 k
W
and the push-button switch is connected to GND.
Contact current, I, is calculated as follows:
V
S
when V
Batt
12 V
I
(100 k
W
2 k
W
)
U 6046 B / U 6047 B
It can be increased by connecting a 5.6 k
W
resistor from the
push-button-switch to V
Batt
as shown in figure 10b.
The connecting diodes prevent the current flow to the input
of the Z-diodes when the rocker actuated-switch is in
open-state (current-consumption only in standby-mode). If
necessary these diodes can be omitted.
[
)
I
[
0.1 mA
+
Timing waveform
Diagram 5A
Toggle
Pin 5
t
3
Relay
Pin 2
t
3
Diagram 5B
ON
t
3
t
3
t
3
t
3
t
3
t
d
Pin 3
t
3
OFF
Pin 4
t
3
Relay
Pin 2
t
3
Diagram 5C
t
3
t
3
t
3
t
3
t
3
t
d
Pin 3
ON
OFF
Pin 4
Relay
Pin 2
t
3
t
d
94 8755
Figure 5 Behaviour of the relay control output as a function of input condition
V
S
2V
VBatt
S
R
20 k
W
7V
15 pF
Pin 3,4,5
–
+
20 k
W
94 8756
94 8757
100 k
W
Pin 3,4,5
2 k
W
2V
–
+
7V
15 pF
Figure 6a Input circuit U 6046 B
Rev. A1: 22.09.1994
Figure 6b Input circuit U 6047 B
5
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