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AD590JCHIPS 数据表(PDF) 6 Page - Analog Devices |
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AD590JCHIPS 数据表(HTML) 6 Page - Analog Devices |
6 / 16 page AD590 Rev. C | Page 6 of 16 PRODUCT DESCRIPTION The AD590H has 60 µ inches of gold plating on its Kovar leads and Kovar header. A resistance welder is used to seal the nickel cap to the header. The AD590 chip is eutectically mounted to the header and ultrasonically bonded to with 1 mil aluminum wire. Kovar composition: 53% iron nominal; 29% ±1% nickel; 17% ±1% cobalt; 0.65% manganese max; 0.20% silicon max; 0.10% aluminum max; 0.10% magnesium max; 0.10% zirconium max; 0.10% titanium max; 0.06% carbon max. The AD590F is a ceramic package with gold plating on its Kovar leads, Kovar lid, and chip cavity. Solder of 80/20 Au/Sn composition is used for the 1.5 mil thick solder ring under the lid. The chip cavity has a nickel underlay between the metallization and the gold plating. The AD590 chip is eutectically mounted in the chip cavity at 410°C and ultrasonically bonded to with 1 mil aluminum wire. Note that the chip is in direct contact with the ceramic base, not the metal lid. When using the AD590 in die form, the chip substrate must be kept electrically isolated (floating) for correct circuit operation. THE AD590 IS AVAILABLE IN LASER-TRIMMED CHIP FORM; CONSULT THE CHIP CATALOG FOR DETAILS V+ V– 42MILS 66MILS Figure 3. Metalization Diagram CIRCUIT DESCRIPTION1 The AD590 uses a fundamental property of the silicon transistors from which it is made to realize its temperature proportional characteristic: if two identical transistors are operated at a constant ratio of collector current densities, r, then the difference in their base-emitter voltage will be (kT/q)(In r). Since both k (Boltzman’s constant) and q (the charge of an electron) are constant, the resulting voltage is directly proportional to absolute temperature (PTAT). In the AD590, this PTAT voltage is converted to a PTAT current by low temperature coefficient thin-film resistors. The total current of the device is then forced to be a multiple of this 1 For a more detailed description, see M.P. Timko, “A Two-Terminal IC Temperature Transducer,” IEEE J. Solid State Circuits, Vol. SC-11, p. 784-788, Dec. 1976. Understanding the Specifications–AD590. PTAT current. Figure 4 is the schematic diagram of the AD590. In this figure, Q8 and Q11 are the transistors that produce the PTAT voltage. R5 and R6 convert the voltage to current. Q10, whose collector current tracks the collector currents in Q9 and Q11, supplies all the bias and substrate leakage current for the rest of the circuit, forcing the total current to be PTAT. R5 and R6 are laser-trimmed on the wafer to calibrate the device at 25°C. Figure 5 shows the typical V–I characteristic of the circuit at 25°C and the temperature extremes. Q1 Q2 R2 1040 Ω Q5 Q3 Q4 C1 26pF Q6 Q7 Q12 R4 11k Ω Q8 Q10 Q9 CHIP SUBSTRATE Q11 1 1 8 R5 146 Ω R6 820 Ω R1 260 Ω + – R3 5k Ω Figure 4. Schematic Diagram 01 2 +150°C 423 298 218 +25°C –55°C 34 SUPPLY VOLTAGE (V) 56 30 Figure 5. V-1 Plot EXPLANATION OF TEMPERATURE SENSOR SPECIFICATIONS The way in which the AD590 is specified makes it easy to apply in a wide variety of applications. It is important to understand the meaning of the various specifications and the effects of supply voltage and thermal environment on accuracy. |
类似零件编号 - AD590JCHIPS |
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类似说明 - AD590JCHIPS |
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