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Электронный компонент: U6046B

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1
Features
Delay Time Range: 3.7 s to 20 h
RC Oscillator Determines Timing Characteristics
Relay Driver with Z-diode
Debounced Input for Toggle Switch
Two Debounced Inputs: ON and OFF
Load-dump Protection
RF Interference Protected
Protection According to ISO/TR7637-1 (VDE 0839)
Inputs Switched to V
Batt
Description
The bi-polar long-term timer U6046B is designed to automatically limit the operation
time of high loads in the harsh automotive enviroment with a preset delay time. With
the power-on-reset function the timers guarantee that current consuming devices are
not operated unintentionally.
The delay time can be interrupted manually, but a retrigger function is not provided.
Figure 1. Block Diagram with External Circuit
Stabilization
Power-on reset
Load-dump detection
Debouncing
Mono-flop
Relay control
output
Oscillator
Frequency divider
ON
OFF
TOGGLE
GND
OSC
V
S
V
stab
6
7
8
3
4
5
1
2
C
2
510
W
47
m
F
V
Batt
OUT
R
2
C
1
R
1
Rear Window
Heating Timer/
Long-term
Timer
U6046B
Rev. 4674AAUTO01/03
2
U6046B
4674AAUTO01/03
Pin Configuration
Figure 2. Pinning
Pin Description
Pin
Symbol
Function
1
GND
Reference point, ground
2
OUT
Relay control output
3
ON
Switch-on input
4
OFF
Switch-off input
5
TOGGLE
Toggle input
6
OSC
RC-oscillator input
7
VSTAB
Stabilized voltage
8
VS
Supply voltage
1
2
3
4
8
7
6
5
GND
OUT
ON
OFF
TOGGLE
OSC
VSTAB
VS
3
U6046B
4674AAUTO01/03
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 3. 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
, C1 = 47 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
4, and the R
1
C
1
circuit is omitted.
Figure 3. Basic Circuit for 12 V Supply and Oscillator
Figure 4. Basic Circuit for V
S
= 5 V
47
m
F/
16 V
510
W
V
Batt
1
2
6
5
8
7
3
4
U6046B
R
1
C
1
C
2
R
2
R
2
1
2
6
5
8
7
3
4
V
S
= 5 V
U6046B
C
2
V
Batt
4
U6046B
4674AAUTO01/03
Oscillator (Pin 6)
The external components R
2
and C
2
determine the oscillator frequency. The capacitor
C
2
is charged by R
2
and discharged by an integrated 2-k
W
resistor.
A stable oscillator frequency with minimal influence of the temperature coefficient of the
integrated resistor is achieved with R
2
>> 2 k
W
.
Oscillator frequency, f, is calculated as follows:
where
t
1
= charge time =
a
1
R
2
C
2
t
2
= discharge time =
a
2
2 k
W
C
2
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
The debounce time, t
3
, and the delay time, t
d
, depend on the oscillator frequency, f, as
follows:
Table 1 shows relationships between t
3
, t
d
, C
2
, R
2
and frequencies from 1 Hz to 20 kHz.
Relay Control Output
(OUT)
The relay control output is an open-collector Darlington circuit with an integrated 23-V
Z-diode to limit 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 at 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 (see Figure 8).
The relay control output is protected via the integrated 23-V Z-diode in the case of short
interference peaks. It is switched to a conductive condition for a battery voltage of
greater than approximate 40 V in the case of a load-dump. The output transistor is
dimensioned so that it can withstand the current produced.
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 out-
put is disabled.
f
1
t
1
t
2
+
---------------
=
t
3
6
1
f
---
=
t
d
73728
1
f
---
=
5
U6046B
4674AAUTO01/03
Figure 5. TOGGLE Function
Relay Control Output
Behavior (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 inter-
rupted after the elapse of delay time, t
d
. There are two input possibilities:
Toggle Input
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 (see
Figure 5).
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)
To avoid simultaneous operation of both inputs, pin 3 (ON) and pin 4 (OFF), use of two-
way contacts with a centre-off position with spring returns (also known as rocker-actu-
ated switch) is recommended (see Figure 6).
Pressing the push-button switch (pin 3-ON) leads to the activation of the relay after the
debounce time, t
3
, whereas 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 because both inputs are
connected to the same debounce stage. Debouncing functions on both edges 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.
47
m
F/
16 V
C
1
510
W
R
2
C
2
V
Batt
1
2
6
5
8
7
3
4
20 k
W
S1
U6046B
R
1