U6049B Datasheet, PDF (3/8 Pages) TEMIC Semiconductors – Radiator Fan Controlled Timer

U6049B
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
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.
Ignition
20 k W
Terminal 15
100 nF
Pin 3
7V
2V
–
+
15 pF
20 kW
94 8813
where
@ _@ ^{t1 = charge time = a1 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
Figure 5. Input circuit for ignition (Pin 3)
Pin 4, 5
–
+
7V
15 pF
94 8815
Figure 6. Input circuit Pin 4 and Pin 5
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 satura-
tion voltage is typically 1.1 V @ 200 mA.
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.
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.
Relay Control Output behavior, Pin 2
The U6049B controls the cooling fan motor in an automo-
bile by means of a relay.
Figure 5 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 volt-
ages greater than 2 V.
For the programming input, Pin 5, and thermal switch
input, Pin 4, there is neither a pull-up nor pull-down resis-
tor integrated internally (see figure 6).
One can reduce the standby current through the internal
Z-diode by selecting a higher value for resistance R₄ (see
figure 8, R₄ up to 200 kW). Resistance R₅ determines the
contact current through the thermal control switch, S_th.
Ignition input (terminal 15) is not debounced. De-
bouncing can be achieved by an external circuit (R₃,C₃)
connected to Pin 3 (see figures 1 and 7).
TELEFUNKEN Semiconductors
3 (8)
Rev. A3, 04-Feb-97