AD590 The 590H has 60 u inches of gold plating on its Kovar leads and In the AD590, this PtAT voltage is converted to a PTAT cur to the header. The AD590 chip is eutectically mounted to the o Kovar header. a resistance welder is used to seal the nickel c ent by low temperature coefficient thin-film resistors. The total current of the device is then forced to be a multiple of this header and ultrasonically bonded to with 1 MIL aluminum PTAT current. Referring to Figure 1, the schematic diagram of wire. Kovar composition: 53% iron nominal; 29%+1% nickel the AD590, Q8 and Qll are the transistors that produce the 17%+ 1% cobalt: 0.65% manganese max: 0. 20% silicon ma PTAT voltage R5 and R6 convert the voltage to current. Q10, 0.10% aluminum max: 0. 10% magnesium max: 0.10% zirco whose collector current tracks the colletor currents in Q9 and nium max: 0.10% titanium max: 0.06% carbon max Q11, supplies all the bias and substrate leakage current for the The 590F is a ceramic package with gol rest of the circuit, forcing the total current to be PtAT. R5 and leads, Kovar lid, and chip cavity Solder of 80/20 Aw/Sn com R6 are laser trimmed on the wafer to calibrate the device at position is used for the 1.5 mil thick solder ring under the lid 25°C. The chip cavity has a nickel underlay between the metalization Figure 2 shows the typical V-I characteristic of the circuit at nd the gold plating. The AD590 chip is eutectically mounted +25.C and the temperature extremes in the chip cavity at 410C 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 METALIZATION DIAGRAM Figure 1. Schematic Diagram CIRCUIT DESCRIPTIONI +150°c The AD590 uses a fundamental property of the silicon transis tors from which it is made to realize its temperature propor- tional characteristic: if two identical transistors are operated at a 如 +25c constant ratio of collector current densities, r. then the differ 55C ence in their base-emitter voltage will be(kT/q (In r). Since both k, Boltzman's constant and g, the charge of an electron are constant, the resulting voltage is directly proportional to absolute temperature (PTAT) SUPPLY VOLTAGE igure 2. V-1 Plot or a more detailed circuit description see M.P. Timko, "A Two-Terminal IC Temperature Transducer, J. Solid State Circuits. Vol SC-11 P.784-788,Dec.1976 REV. BAD590 –4– REV. B The 590H 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% zirco￾nium max; 0.10% titanium max; 0.06% carbon max. The 590F is a ceramic package with gold plating on its Kovar leads, Kovar lid, and chip cavity. Solder of 80/20 Au/Sn com￾position is used for the 1.5 mil thick solder ring under the lid. The chip cavity has a nickel underlay between the metalization 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. METALIZATION DIAGRAM CIRCUIT DESCRIPTION1 The AD590 uses a fundamental property of the silicon transis￾tors from which it is made to realize its temperature propor￾tional characteristic: if two identical transistors are operated at a constant ratio of collector current densities, r, then the differ￾ence 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). 1 For a more detailed circuit description see M.P. Timko, “A Two-Terminal IC Temperature Transducer,” IEEE J. Solid State Circuits, Vol. SC-11, p. 784-788, Dec. 1976. In the AD590, this PTAT voltage is converted to a PTAT cur￾rent by low temperature coefficient thin-film resistors. The total current of the device is then forced to be a multiple of this PTAT current. Referring to Figure 1, the schematic diagram of the AD590, 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 colletor 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 2 shows the typical V–I characteristic of the circuit at +25°C and the temperature extremes. Figure 1. Schematic Diagram Figure 2. V–I Plot