安森美半导体ESD保护器件SRDA3.3-4-D 数据手册.pdf

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安森美半导体ESD保护器件SRDA3.3-4-D 数据手册pdf,安森美半导体ESD保护器件SRDA3.3-4-D 数据手册
SRDA33-4 APPLICATIONS INFORMATION The SRDA33-4 is a low capacitance TvS diode array Option 2 designed to protect sensitive electronics such as Protection of four data lines with bias and power supply communications systems, computers, and computer isolation resistor peripherals against damage due to ESD events or transient overvoltage conditions. Because of its low capacitance, it 1O 1 can be used in high speed l/o data lines. The integrated lo 20 design of the SrDA33-4 offers surge rated, low NcC capacitance steering diodes and a tvs diode integrated in a single package(So-8). If a transient condition occurs, the 10K 2 7■ steering diodes will drive the transient to the positive rail of the power supply or to ground. The tvs device protects the power line against overvoltage conditions avoiding damage to the power supply and other downstream components 1/O3 SRDA33-4 Configuration Options 10 40 The srda33-4 is able to protect up to four data lines gainst transient overvoltage conditions by driving them to Figure 4. a fixed reference point for clamping purposes. The steerin The SRDA33-4 can be isolated from the power supply by diodes will be forward biased whenever the voltage on the connecting a series resistor between pins 2 and 3 and Vcc protected line exceeds the reference voltage (Vf or A 10 kS2 resistor is recommended for this application. This VCC+vi. The diodes will force the transient current to will maintain a bias on the internal TVS and steering diodes, bypass the sensitive circuit reducing their capacitance Data lines are connected at pins 1, 4, 6 and 7. The negative reference is connected at pins 5 and 8. These pins must be Option 3 connected directly to ground using a ground plane to Protection of four data lines using the internal Tvs diode minimize the PCBs ground inductance. It is very important as reference lo reduce the PCB trace lengths as much as possible to minimize parasitic inductances 10 1 10 2 Option 1 Protection of four data lines and the power supply using 8凵 VcC as reference. NC一园 NC一 + _6冒 /O2 8囗h 10 3 2 7囗 O 图"16n Figure 5. 5囗h In applications lacking a positive supply reference or those cases in which a fully isolated power supply /O3 required, the internal Tvs can be used as the reference. For 10 4 these applications, pins 2 and 3 are not connected. In this Figure 3 configuration, the steering diodes will conduct whenever the voltage on the protected line exceeds the working voltage of For this configuration, connect pins 2 and 3 directly to the the TVs plus one diode drop (vc=vf+ VTvs) positive supply rail(Vcc). The data lines are referenced to supply voltage. The internal Tvs diode prevents overvoltage on the supply rail. Biasing of the steering diodes reduces their capacitance http://onsemi 3 SRDA33-4 ESD Protection of Power Supply Lines L diesd/dt factor a relatively small trace inductance can result When using diodes for data line protection, referencing to n hundreds of volts appearing on the supply rail. This a supply rail provides advantages. Biasing the diodes reduces endangers both the power supply and anything attached to their capacitance and minimizes signal distortion. that rail. This highlights the importance of good board layout Implementing this topology with discrete devices does have Taking care to minimize the effects of parasitic inductance disadvantages. This configuration is shown below will provide significant benefits in transient immunity Even with good board layout, some disadvantages are still Power present when discrete diodes are used to suppress esd events Supply ESDpos across datalines and the supply rail Discrete diodes with good Transient power capability will have larger die and therefore higher capacitance. This capacitance becomes problematic as D1 SPas Protected Data Line ESDneg transmission frequencies increase. Reducing capacitance Device generally requires reducing die size. These small die will have higher forward voltage characteristics at typical ESD D2 vF+V⌒ transient current levels. This voltage combined with the ESDneg smaller die can result in device failure The on Semiconductor SRDA33-4 was developed to overcome the disadvantages encountered when using discrete Figure 6 diodes for ESd protection. This device integrates a TVS Looking at the figure above, it can be seen that when a diode within a network of steering diodes positive esd condition occurs, diode d1 will be forward biased while diode d2 will be forward biased when a negative D5 D7 ESD condition occurs. For slower transient conditions. this systen may be approximated as follows For positive pulse conditions Vc=Ⅴcc+Ⅴfp1 D2 D4 D6 For negative pulse conditions Vc=-ViD ESd events can have rise times on the order of some number of nanoseconds. Under these conditions. the effect of parasitic inductance must be considered. A pictorial Figure 8. SRDA33-4 Equivalent Circuit representation of this is shown below g an ESD condition, the ESd current will be driven Power to ground through the tvs diode as shown below Supply ESDpos Power Supply D1ESDpos YY ESDn Device D1 lEs Data line D2. Vc=VcC +Vf+(L dIESD/dt) Protected le SDneg Device Data Line Vc=-Vf-(L diESD/dt) Figure 7. An approximation of the clamping voltage for these fast Figure 9 transients would be The resulting clamping voltage on the protected iC will For positive pulse conditions +Ⅴf+( L diesD/dt Vc=VFD+ TVs The clamping voltage of the Tvs diode is provided For negative pulse conditions Figure 2 and depends on the magnitude of the Esd current Vf-(l diesD/at The steering diodes are fast switching devices with unique As shown in the formulas, the clamping voltage(Vc)not only depends on the vf of the steering diodes but also on the forward voltage and low capacitance characteristics http://onsemi.co SRDA33-4 TYPICAL APPLICATIONS UPSTREAM USB PORT s s BUS D D+ R DOWNSTREAM USB PORT BUS USB BUS GND Controller SRDA3 3-4 GND T vBUS NUP2201 MR6 D+DOWNSTREAM R USB PORT GND CTIC Figure 10. ESD Protection for USB Port RJ45 Connector TX+ TX+ TX PHY Transformers Ethernet rx+ RX+ R RX SRDA3 3-4 GND N/C NC Figure 11. Protection for Ethernet 10/100 Differential Mode) http://onsemi.co SRDA33-4 RTIP R2 RRING T1/E1 TRANSCEIVER SRDA3 3-4 R4 TTIP TRING T2 Figure 12. tI/E1 Interface Protection http://onsemi.co 6 SRDA33-4 PACKAGE DIMENSIONS SOIC-8 NB CASE751-07 ISSUE AJ NOTES: 1. DIMENSIONINC AND TOLERANCING PER ANSY145M,1982 A 2 CONTROLLING DIMENSION MILLIMETER 3. DIMENSION A AND B DC NOT INCLUDE MOLD PROTRUSION 4. MAXIMUM MOLD PROTRUSION 0. 15(0.006) PER SIDE DIMENSION D DOES NOT INCLUDE DAMBAR s40250000 PROTRUSION, ALLOWABLE DAMBAR PROTRUSION SHALL BE 0. 127(0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION 6. 751-01 THRU 751-06 ARE OBSOLETE NEW STANDARD IS 751-07 MILLIMETERS INCHES DIM_MIN|MAⅩ NX45c B3804000.150C.157 SEATING 033 t / PLANE 1.27BSC 0. 050 BSC 0.100004) H0,100.250.004c.010 H kK0401270016c050 M N0250.500010c020 0250010zY⑥X 580 6200.228C.244 SOLDERING FOOTPRINT* 1.52 7.0 4.0 0.275 0.155 0.6 .270 0.024 0.050 CALE 6: 1 For additional information on our Pb-Free strategy and soldering details, please download the on Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D ON Semiconductor and () arc registered trademarks of Semiconductor Components Industrics, LLC (SCILLC). SCILLC reserves the right to make changos without further notico Typical" parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. Al operating parameters, including "Typicals" must be validated for each customer applicatian by customer's technical experts. SCILLC does not convey any license under its patent ngts nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant in o the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLc oroduct could create a situation where personal injury or death may occur. Should Buyer purchase or use SCiLLC products for any such unintended or unauthorized application, Buyer shall indemnify anc hold Scillc and its officers, employees, subsidiaries, affiliates and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT N.AmericanTechnicalSupport800-282-9855TollFreeOnSemiconductorWebsitewww.onseml.com Literature Distribution Center for oN Semiconductor USA/Canada PO. Box 5163. Denver Colorado 80217 USA Europe, Middle East and Africa Technical Support: OrderLiterature:http://www.onsemi.com/orderlit Phone: 303-675-2175 or 800-344-3860 Toll Free USA Canada Phone: 421 33790 2910 Fax: 303-675-2176 or B00-344-3867 Toll Free USA/Canada Japan Customer Focus Center For additional information, please contact your local Email:orderlit@onsemi.com Phone:81-3-5773-3850 Sales Representative SRDA3.3-4/D

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