U479B_07 Datasheet, PDF (1/7 Pages) ATMEL Corporation – Automotive Lamp-outage Monitor IC

Features
• 2-kV ESD Protection
• Two Comparators with Common Reference
• Tight Threshold Tolerance
• Threshold Matched to PTC Characteristic of Incandescent Lamps
• Temperature Compensated
• NPN Output
• Interference and Damage-protection According to VDE 0839
• EMI Protection
• Reversal Polarity Protection
• Load-dump Protection
Automotive
Lamp-outage
Monitor IC
1. Description
The monolithic integrated bipolar circuit, U479B, is designed as a monitor for lamp fail-
ure in automobiles. The comparator threshold is matched to the PTC characteristic of
incandescent lamps. The threshold is tied to V_4,6 = V_S – V_T where V_T = 8 mV.
If the voltage drop across the shunt resistor, R_sh, 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. A comparator input, which is not used, must be connected to
pin 7.
Figure 1-1. Schematic and Application Circuit
V_S
2
7
R_sh
Z₂
4
-
&
+
R_sh
8
0.6 V_S
-
+
V_Batt
5 _OUT1
-
3
OUT2
+
&
6
U479B
Lamps
1
R₁ 150 Ω
Rev. 4775B–AUTO–09/05