U6044B Datasheet, PDF (3/7 Pages) TEMIC Semiconductors – Radiator fan controlled timer

TELEFUNKEN Semiconductors
U 6044 B
Oscillator, Pin 6
Oscillator frequency, f, is determined mainly by
R₂C₂-circuit. Resistance, R₂, determines the charge time,
whereas the integrated resistance (2 kW) is responsible for
discharge time. For the stability of the oscillator frequency,
it is recommended to select R₂ much greater than internal
resistance (2 kW), 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
t₁ t₂
where
@ @ ^t1 ^{= charge time = a}1 ^R2 ^C2
@ _@ t₂ = discharge time = a₂ 2 kW C₂
a₁ and a₂ are constants and has
a₁ = 0.833 and a₂ = 1.551 when C₂ = 470 pF to 10 nF
a₁ = 0.746 and a₂ = 1.284 when C₂ = 10 nF to 4700 nF
Debounce time, t₃, and the delay time, t_d, depend on the
oscillator frequency, f, as follows:
+ @ t₃
6
1
f
+ @ t_d
73728
1
f
Table 1 shows relationships between t₃, t_d, C₂, R₂ and
frequencies from 1 Hz to 20 kHz.
Output, Pin 2
Output Pin 2 is an open collector Darlington circuit with
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 the
saturation voltage is typically 1.1 V @ 200 mA.
The output stage can be activated
D directly with the AC input independent of the ignition
input and S_th input
D during the delay time which is started by the ignition
input with the S_th input
Interference voltages and load dump
The IC supply is protected by R₁, C₁, and an integrated
Z-diode, while the inputs are protected by a series resistor,
integrated Z-diode and RF-capacitor (refer to Figure 3).
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.
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
control output is disabled.
Input stages
Ignition
20 k W
Terminal 15
100 nF
Pin 3
7V
2V
–
+
15 pF
20 kW
94 8813
Figure 3a Input circuit for ignition (Pin 3)
Pin 4, 5
V_S (Pin 8)
–
+
15 pF
94 8815
Figure 3b Input circuit Pin 4 and Pin 5
Figure 3a shows the internal input circuit of ignition
(Pin 3). It has an integrated pull-down resistor (20 kW),
RF-capacitor (15 pF) and 7-V Z-diode. It reacts to voltages
greater than 2 V.
The thermal switch input, S_th, is internally debounced and
only needs an external protection resistor. The air
conditioning input, AC, and the signal input, ignition, are
not debounced and external R/C filters are recommended
to prevent the integrated circuit from unintentional
activation by transients.
The ignition input is switched to V_Batt, the S_th and AC
inputs are switched to GND and need pull up resistors
externally (figure 3b).
The detection threshold voltage of all three input stages is
typically 2 V.
Ignition input (terminal 15) is not debounced. Debouncing
can be achieved by external circuit (R₃,C₃) connected to
Pin 3 (see figures 1 and 5).
Rev. A1: 12.12.1994
3