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U4790B
Automotive Lamp-Outage Monitor, VT = 8 mV, VZ(3,5) = 22 V
Description
The bipolar IC U4790B is designed as a monitor for lamp failure in automobiles. The comparator threshold is matched to the PTC characteristic of incandescent lamps. The threshold is tied to a typical value of V4,6 = VS – VT where VT = 8 mV. If the voltage drop across shunt resistor, Rsh, exceeds 8 mV, the output is turned off, otherwise the output is turned on. Without supply voltage or open input Pin 8, the output is turned off. An unused comparator input must be connected to Pin 7.
Features
D 10 kV–ESD protection D Two comparators with common reference D Tight threshold tolerance D Threshold matched to PTC characteristic of incandescent lamps D Temperature compensated D NPN output D Interference and damage–protection according to VDE 0839 D EMI protection D Reversal polarity protection D Load-dump protection
Ordering Information
Extended Type Number U4790B Package DIP8 Remarks
Block Diagram
VS 2 Rsh Z2 – + & Z5 0.6 VS – + 8 – + 6 Z3 1
95 10606
VBatt 7
5 OUT1
4 Rsh
3 OUT2 &
Lamps
R1
150 W
Figure 1. Schematic and application circuit
TELEFUNKEN Semiconductors Rev. A2, 03-Dec-97
1 (5)
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U4790B
Pin Description
Input switch VRef IN2 OUT1 Pin 1 2 3 4 5 6 7 8 Symbol GND VS OUT2 IN1 OUT1 IN2 VRef Input Function Reference point, ground Supply voltage Output 2 Input 1 Output 1 Input 2 Reference voltage Input switch
GND VS OUT2 IN1
1 2 3 4
95 10634
8 7 6 5
Figure 2. Pinning
Absolute Maximum Ratings
Parameters Supply voltage Current consumption t = 2 ms, measured at Pin 1 (GND) Output current Input voltage reference point Pin 7 Power dissipation DIP 8 Tamb = 95 °C Tamb = 60 °C DIP 8 Ambient temperature range Storage temperature range Junction temperature Pin 2, 7 Pin 1 Pin 3, 5 Pin 4, 6 Symbol VS I1 I3,5 –V4,6 Ptot Ptot Tamb Tstg Tj Value 16.5 1.5 20 6 420 690 –40 to +95 –55 to +125 150 Unit V A mA V mW mW °C °C °C
Thermal Resistance
Parameters Junction ambient DIP8 Symbol RthJA Value 110 Unit K/W
2 (5)
TELEFUNKEN Semiconductors Rev. A2, 03-Dec-97
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U4790B
Electrical Characteristics
VS = 9 to 15 V, Tamb = –40 to +95 °C, figure 1, unless otherwise specified Parameters Supply voltage Internal Z diode Z2 Current consumption Test Conditions / Pin Pin 2,7 Pin 2 VS = 12 V Pin 1 measured at Pin 1 (GND) Output saturation voltage VS = 9 V, I3,5 = 10 mA Pin 3,5 Tamb = 25 °C Output Z diodes Z3, Z5 Pin 3,5 Control signal threshold Reference point Pin 7 (V7) Pin 4,6 I3,5 = 3 mA VS = 12 V VS = 15 V * VT(12V) V Voltage drift Pin 4,6 D V + T(15V)
15 V
Symbol VS VZ I1
Min 9 20
Typ
Max 15 6
4.5
Unit V V mA
Vsat VZ
0.5 21
V V
–VT
6.5 7.8
8 9.3 0.45 0.6 VS 100 5
9.5 10.8
mV mV/V V nA
* 12V
DV
V8 II
Threshold voltage Input currents Delay time
Switch identification Pin 8 Pin 4,6 Switch-on High to low Switch-off Low to high Pin 8 Pin 3,5
mA ms ms
td(on) td(off)
6 .