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| High Performance Schottky Diode for Transient Suppression Technical Data HSMS-2700/-2702 -270B/-270C Features * Ultra-low Series Resistance for Higher Current Handling * Picosecond Switching * Low Capacitance Package Lead Code Identification (Top View) SINGLE 3 SERIES 3 Description The HSMS-2700 series of Schottky diodes, commonly referred to as clipping /clamping diodes, are optimal for circuit and waveshape preservation applications with high speed switching. Ultra-low series resistance, R S, makes them ideal for protecting sensitive circuit elements against higher current transients carried on data lines. With picosecond switching, the HSMS-270x can respond to noise spikes with rise times as fast as 1 ns. Low capacitance minimizes waveshape loss that causes signal degradation. Applications RF and computer designs that require circuit protection, highspeed switching, and voltage clamping. 1 0, B 2 1 2, C 2 HSMS-270x DC Electrical Specifications, TA = +25C [1] Part Package Number Marking Lead HSMS- Code [2] Code Configuration -2700 J0 -270B -2702 J2 -270C C B 2 Series 0 Single Maximum Minimum Typical Maximum Forward Breakdown Typical Series Eff. Carrier Voltage Voltage Capacitance Resistance Lifetime VF (mV) VBR (V) C T (pF) R S () (ps) Package SOT-23 SOT-323 (3-lead SC-70) SOT-23 SOT-323 (3-lead SC-70) 550 [3] 15 [4] 6.7 [5] 0.65 100 [6] Notes: 1. TA = +25C, where TA is defined to be the temperature at the package pins where contact is made to the circuit board. 2. Package marking code is laser marked. 3. I F = 100 mA; 100% tested 4. I F = 100 A; 100% tested 5. VF = 0; f =1 MHz 6. Measured with Karkauer method at 20 mA; guaranteed by design. 2 Absolute Maximum Ratings, TA= 25C Symbol IF I F-peak PT PINV TJ TSTG JC Parameter DC Forward Current Peak Surge Current (1s pulse) Total Power Dissipation Peak Inverse Voltage Junction Temperature Storage Temperature Thermal Resistance, junction to lead Unit mA A mW V C C C/W Absolute Maximum [1] HSMS-2700/-2702 350 1.0 250 15 150 -65 to 150 500 HSMS-270B/-270C 750 1.0 825 15 150 -65 to 150 150 Note: 1. Operation in excess of any one of these conditions may result in permanent damage to the device. Linear and Non-linear SPICE Model 0.08 pF SPICE Parameters Parameter BV CJO EG IBV IS N RS PB PT M Unit V pF eV A A V Value 25 6.7 0.55 10E-4 1.4E-7 1.04 0.65 0.6 2 0.5 2 nH RS SPICE model 3 Typical Performance I F - FORWARD CURRENT (mA) I F - FORWARD CURRENT (mA) 100 TJ - JUNCTION TEMPERATURE (C) 300 500 100 160 Max. safe junction temp. 140 TA = +75C TA = +25C 120 TA = -25C 100 80 60 40 20 0 0 50 100 150 200 250 300 350 IF - FORWARD CURRENT (mA) 10 10 1 1 0.1 0.01 0 0.1 0.2 0.3 TA = +75C TA = +25C TA = -25C 0.4 0.5 0.6 VF - FORWARD VOLTAGE (V) 0.1 0.01 0 TA = +75C TA = +25C TA = -25C 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 VF - FORWARD VOLTAGE (V) Figure 1. Forward Current vs. Forward Voltage at Temperature for HSMS-2700 and HSMS-2702. Figure 2. Forward Current vs. Forward Voltage at Temperature for HSMS-270B and HSMS-270C. Figure 3. Junction Temperature vs. Forward Current as a Function of Heat Sink Temperature for the HSMS-2700 and HSMS-2702. Note: Data is calculated from SPICE parameters. TJ - JUNCTION TEMPERATURE (C) 160 Max. safe junction temp. 140 TA = +75C TA = +25C 120 T = -25C A 100 80 60 40 20 0 0 150 300 450 600 750 IF - FORWARD CURRENT (mA) 7 CT - TOTAL CAPACITANCE (pF) 6 5 4 3 2 1 0 5 10 15 20 VF - REVERSE VOLTAGE (V) Figure 4. Junction Temperature vs. Current as a Function of Heat Sink Temperature for HSMS-270B and HSMS-270C. Note: Data is calculated from SPICE parameters. Figure 5. Total Capacitance vs. Reverse Voltage. 4 Package Dimensions Outline SOT-23 1.02 (0.040) 0.89 (0.035) 0.54 (0.021) 0.37 (0.015) 3 1.40 (0.055) 1.20 (0.047) 2 2.65 (0.104) 2.10 (0.083) PACKAGE MARKING CODE XX 1 0.50 (0.024) 0.45 (0.018) 2.04 (0.080) 1.78 (0.070) TOP VIEW 0.152 (0.006) 0.066 (0.003) 1.02 (0.041) 0.85 (0.033) 3.06 (0.120) 2.80 (0.110) 0.10 (0.004) 0.013 (0.0005) SIDE VIEW DIMENSIONS ARE IN MILLIMETERS (INCHES) 0.69 (0.027) 0.45 (0.018) END VIEW Tape Dimensions and Product Orientation For Outline SOT-23 D0 t COVER TAPE P2 P0 10 PITCHES CUMULATIVE TOLERANCE ON TAPE 0.2 MM (0.008) EMBOSSMENT E A KC B F W USER FEED DIRECTION P1 T CENTER LINES OF CAVITY D1 DESCRIPTION CAVITY LENGTH WIDTH DEPTH PITCH BOTTOM HOLE DIAMETER DIAMETER PITCH POSITION WIDTH THICKNESS WIDTH TAPE THICKNESS CAVITY TO PERFORATION (WIDTH DIRECTION) CAVITY TO PERFORATION (LENGTH DIRECTION) SYMBOL A B K P1 D1 D0 P0 E W t C T F P2 SIZE (mm) 3.15 0.15 2.65 0.25 1.30 0.10 4.00 0.10 1.00 min. 1.55 + 0.10/-0 4.00 0.10 1.75 0.10 8.00 0.2 0.30 0.05 5.40 0.25 0.064 0.01 3.50 0.10 2.00 0.05 SIZE (INCHES) 0.124 0.006 0.104 0.010 0.051 0.004 0.157 0.004 0.04 min. 0.061 + 0.004/-0 0.157 0.004 0.069 0.004 0.315 0.008 0.012 0.002 0.205 0.010 0.003 0.0004 0.138 0.004 0.079 0.002 PERFORATION CARRIER TAPE COVER TAPE DISTANCE BETWEEN CENTERLINE 5 Package Dimensions Outline SOT-323 (SC-70 3 Lead) 1.30 (0.051) REF. PACKAGE MARKING CODE 2.20 (0.087) 2.00 (0.079) xx 1.35 (0.053) 1.15 (0.045) 0.650 BSC (0.025) 2.20 (0.087) 1.80 (0.071) 0.10 (0.004) 0.00 (0.00) 0.425 (0.017) TYP. 0.30 REF. 0.25 (0.010) 0.15 (0.006) 1.00 (0.039) 0.80 (0.031) 10 0.30 (0.012) 0.10 (0.004) 0.20 (0.008) 0.10 (0.004) DIMENSIONS ARE IN MILLIMETERS (INCHES) Tape Dimensions and Product Orientation For Outline SOT-323 (SC-70 3 Lead) P P0 D P2 E F W C D1 t1 (CARRIER TAPE THICKNESS) Tt (COVER TAPE THICKNESS) 8 MAX. K0 5 MAX. A0 B0 DESCRIPTION CAVITY LENGTH WIDTH DEPTH PITCH BOTTOM HOLE DIAMETER DIAMETER PITCH POSITION WIDTH THICKNESS WIDTH TAPE THICKNESS CAVITY TO PERFORATION (WIDTH DIRECTION) CAVITY TO PERFORATION (LENGTH DIRECTION) SYMBOL A0 B0 K0 P D1 D P0 E W t1 C Tt F P2 SIZE (mm) 2.24 0.10 2.34 0.10 1.22 0.10 4.00 0.10 1.00 + 0.25 1.55 0.05 4.00 0.10 1.75 0.10 8.00 0.30 0.255 0.013 5.4 0.10 0.062 0.001 3.50 0.05 2.00 0.05 SIZE (INCHES) 0.088 0.004 0.092 0.004 0.048 0.004 0.157 0.004 0.039 + 0.010 0.061 0.002 0.157 0.004 0.069 0.004 0.315 0.012 0.010 0.0005 0.205 0.004 0.0025 0.00004 0.138 0.002 0.079 0.002 PERFORATION CARRIER TAPE COVER TAPE DISTANCE 6 Applications Information Schottky Diode Fundamentals The HSMS-270x series of clipping/ clamping diodes are Schottky devices. A Schottky device is a rectifying, metal-semiconductor contact formed between a metal and an n-doped or a p-doped semiconductor. When a metalsemiconductor junction is formed, free electrons flow across the junction from the semiconductor and fill the free-energy states in the metal. This flow of electrons creates a depletion or potential across the junction. The difference in energy levels between semiconductor and metal is called a Schottky barrier. P-doped, Schottky-barrier diodes excel at applications requiring ultra low turn-on voltage (such as zero-biased RF detectors). But their very low, breakdown-voltage and high series-resistance make them unsuitable for the clipping and clamping applications involving high forward currents and high reverse voltages. Therefore, this discussion will focus entirely on n-doped Schottky diodes. Under a forward bias (metal connected to positive in an n-doped Schottky), or forward voltage, VF, there are many electrons with enough thermal energy to cross the barrier potential into the metal. Once the applied bias exceeds the built-in potential of the junction, the forward current, IF, will increase rapidly as VF increases. When the Schottky diode is reverse biased, the potential barrier for electrons becomes large; hence, there is a small probability that an electron will have sufficient thermal energy to cross the junction. The reverse leakage current will be in the nanoampere to microampere range, depending upon the diode type, the reverse voltage, and the temperature. In contrast to a conventional p-n junction, current in the Schottky diode is carried only by majority carriers (electrons). Because no minority-carrier (hole) charge storage effects are present, Schottky diodes have carrier lifetimes of less than 100 ps. This extremely fast switching time makes the Schottky diode an ideal rectifier at frequencies of 50 GHz and higher. Another significant difference between Schottky and p-n diodes is the forward voltage drop. Schottky diodes have a threshold of typically 0.3 V in comparison to that of 0.6 V in p-n junction diodes. See Figure 6. Both diodes have similar barrier heights; and this is indicated by corresponding values of saturation current, I S. Yet, different contact diameters and epitaxiallayer thickness result in very different values of C J and R S. This is seen by comparing their SPICE parameters in Table 1. Table 1. HSMS-270x and HBAT-540x SPICE Parameters. Parameter BV CJ0 EG IBV IS N RS PB PT M HSMS270x 25 V 6.7 pF 0.55 eV 10E-4 A 1.4E-7 A 1.04 0.65 0.6 V 2 0.5 HBAT540x 40 V 3.0 pF 0.55 eV 10E-4 A 1.0E-7 A 1.0 2.4 0.6 V 2 0.5 P N METAL N CAPACITANCE CURRENT CAPACITANCE CURRENT 0.6 V 0.3V - + - + BIAS VOLTAGE BIAS VOLTAGE PN JUNCTION SCHOTTKY JUNCTION Figure 6. Through the careful manipulation of the diameter of the Schottky contact and the choice of metal deposited on the n-doped silicon, the important characteristics of the diode (junction capacitance, CJ ; parasitic series resistance, R S; breakdown voltage, V BR; and forward voltage, V F,) can be optimized for specific applications. The HSMS-270x series and HBAT-540x series of diodes are a case in point. At low values of IF 1 mA, the forward voltages of the two diodes are nearly identical. However, as current rises above 10 mA, the lower series resistance of the HSMS-270x allows for a much lower forward voltage. This gives the HSMS-270x a much higher current handling capability. The trade-off is a higher value of junction capacitance. The forward voltage and current plots illustrate the differences in these two Schottky diodes, as shown in Figure 7. 7 300 100 I F - FORWARD CURRENT (mA) HSMS-270x HBAT-540x 10 1 .1 .01 0 0.1 0.2 0.3 0.4 0.5 0.6 VF - FORWARD VOLTAGE (V) Figure 7. Forward Current vs. Forward Voltage at 25C. Consider the circuit shown in Figure 8, in which two Schottky diodes are used to protect a circuit from noise spikes on a stream of digital data. The ability of the diodes to limit the voltage spikes is related to their ability to sink the associated current spikes. The importance of current handling capacity is shown in Figure 9, where the forward voltage generated by a forward current is compared in two diodes. 6 Maximum reliability is obtained in a Schottky diode when the steady state junction temperature is maintained at or below 150C, although brief excursions to higher junction temperatures can be tolerated with no significant impact upon mean-time-to-failure, MTTF. In order to compute the junction temperature, Equations (1) and (3) below must be simultaneously solved. 11600 (V F - I F R S ) IF = IS e nTJ -1 (1) Because the automatic, pick-andplace equipment used to assemble these products selects dice from adjacent sites on the wafer, the two diodes which go into the HSMS-2702 or HSMS-270C (series pair) are closely matched -- without the added expense of testing and binning. Current Handling in Clipping/ Clamping Circuits The purpose of a clipping/clamping diode is to handle high currents, protecting delicate circuits downstream of the diode. Current handling capacity is determined by two sets of characteristics, those of the chip or device itself and those of the package into which it is mounted. noisy data-spikes current limiting Vs VF - FORWARD VOLTAGE (V) 5 4 3 2 1 0 0 0.1 0.2 0.3 0.4 0.5 IF - FORWARD CURRENT (mA) Rs = 1.0 Rs = 7.7 2 1 1 T J n -4060 T J - 298 e IS = I0 298 TJ = V F I F JC + TA (2) (3) Figure 9. Comparison of Two Diodes. long cross-site cable pull-down (or pull-up) 0V voltage limited to Vs + Vd 0V - Vd Figure 8. Two Schottky Diodes Are Used for Clipping/Clamping in a Circuit. The first is a conventional Schottky diode of the type generally used in RF circuits, with an RS of 7.7 . The second is a Schottky diode of identical characteristics, save the R S of 1.0 . For the conventional diode, the relatively high value of RS causes the voltage across the diode's terminals to rise as current increases. The power dissipated in the diode heats the junction, causing R S to climb, giving rise to a runaway thermal condition. In the second diode with low R S, such heating does not take place and the voltage across the diode terminals is maintained at a low limit even at high values of current. where: IF = forward current IS = saturation current V F = forward voltage RS = series resistance TJ = junction temperature IO = saturation current at 25C n = diode ideality factor JC = thermal resistance from junction to case (diode lead) = package + chip T A = ambient (diode lead) temperature Equation (1) describes the forward V-I curve of a Schottky diode. Equation (2) provides the value for the diode's saturation current, which value is plugged into (1). Equation (3) gives the value of junction temperature as a function of power dissipated in the diode and ambient (lead) temperature. The key factors in these equations are: RS, the series resistance of the diode where heat is generated under high current conditions; chip, the chip thermal resistance of the Schottky die; and package, or the package thermal resistance. RS for the HSMS-270x family of diodes is typically 0.7 and is the lowest of any Schottky diode available from Agilent. Chip thermal resistance is typically 40C/W; the thermal resistance of the iron-alloy-leadframe, SOT-23 package is typically 460C/W; and the thermal resistance of the copper-leadframe, SOT-323 package is typically 110C/W. The impact of package thermal resistance on the current handling capability of these diodes can be seen in Figures 3 and 4. Here the computed values of junction temperature vs. forward current are shown for three values of ambient temperature. The SOT323 products, with their copper leadframes, can safely handle almost twice the current of the larger SOT-23 diodes. Note that the term "ambient temperature" refers to the temperature of the diode's leads, not the air around the circuit board. It can be seen that the HSMS-270B and HSMS-270C products in the SOT-323 package will safely withstand a steady-state forward current of 550 mA when the diode's terminals are maintained at 75C. For pulsed currents and transient current spikes of less than one microsecond in duration, the junction does not have time to reach thermal steady state. Moreover, the diode junction may be taken to temperatures higher than 150C for short time-periods without impacting device MTTF. Because of these factors, higher currents can be safely handled. The HSMS-270x family has the highest current handling capability of any Agilent diode. Part Number Ordering Information Part Number HSMS-2700-BLK HSMS-2700-TR1 HSMS-2700-TR2 HSMS-2702-BLK HSMS-2702-TR1 HSMS-2702-TR2 HSMS-270B-BLK HSMS-270B-TR1 HSMS-270B-TR2 HSMS-270C-BLK HSMS-270C-TR1 HSMS-270C-TR2 No. of Devices 100 3,000 10,000 100 3,000 10,000 100 3,000 10,000 100 3,000 10,000 Container Antistatic Bag 7" Reel 13" Reel Antistatic Bag 7" Reel 13" Reel Antistatic Bag 7" Reel 13" Reel Antistatic Bag 7" Reel 13" Reel www.semiconductor.agilent.com Data subject to change. Copyright (c) 1999 Agilent Technologies Obsoletes 5967-6196E 5968-2351E (11/99) |
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