KBMF ® IPAD™ EMI FILTER AND LINE TERMINATION FOR PS/2 MOUSE OR KEYBOARD PORTS MAIN APPLICATIONS EMI Filter and line termination for mouse and keyboard ports on: ■ ■ ■ ■ Desktop computers Notebooks Workstations Servers FEATURES ■ Integrated low pass filters for Data and Clock lines ■ Integrated ESD protection ■ Integrated pull-up resistors ■ Small package size ■ Breakdown voltage: VBR = 6V min. DESCRIPTION SOT23-6L (Plastic) Table 1: Order Code Part Number KBMF01SC6 ■ ■ ■ EMI / RFI noise suppression ESD protection exceeding IEC61000-4-2 level 4 High flexibility in the design of high density boards KM1 Figure 1: Functional Diagram On the implementation of computer systems, the radiated and conducted EMI should be kept within the required levels as stated by the FCC regulations. In addition to the requirements of EMC compatibility, the computing devices are required to tolerate ESD events and remain operational without user intervention. The KBMF implements a low pass filter to limit EMI levels and provide ESD protection which exceeds IEC 61000-4-2 level 4 standard. The device also implements the pull up resistors needed to bias the data and clock lines. The package is the SOT23-6L which is ideal for situations where board space is at a premium. BENEFITS Marking +Vcc Rp Rs Dat Out Dat In C C +Vcc Gnd +Vcc Rp Rs Clk In Clk Out C C Rs Rp C Code 01 39Ω 4.7kΩ 120pF Tolerance ±10% ±10% ±20% COMPLIES WITH THE FOLLOWING ESD STANDARDS: IEC 61000-4-2 (R = 330Ω C = 150pF) Level 4 ±15 kV (air discharge) ±8 kV (contact discharge) MIL STD 883C, Method 3015-6 Class 3 C = 100pF R = 1500Ω 3 positive strikes and 3 negative strikes (F = 1 Hz) TM: IPAD is a trademark of STMicroelectronics. October 2004 REV. 2 1/8 KBMF Table 2: Absolute Maximum Ratings (Tamb = 25°C) Symbol VPP Tj Tstg Parameter Value Unit ESD discharge R = 330W C = 150pF contact discharge ESD discharge - MIL STD 883 - Method 3015-6 ±12 ±25 kV Junction temperature 150 °C - 55 to +150 °C 260 °C 0 to 70 °C 100 mW Storage temperature range TL Lead solder temperature (10 second duration) Top Operating temperature Range Pr Power rating per resistor Table 3: Electrical Characteristics (Tamb = 25°C) Symbol IR VBR VF Parameters Test conditions Diode leakage current VRM = 5.0V Diode breakdown voltage IR = 1mA Diode forward voltage drop IF = 50mA Min Typ Max Unit 10 µA 6 V 0.9 V TECHNICAL INFORMATION 1. EMI FILTERING The KBMFxxSC6 ensure a filtering protection against ElectroMagnetic and RadioFrequency Interferences thanks to its low-pass filter structure. This filter is characterized by the following parameters : - cut-off frequency - Insertion loss - high frequency rejection Figure 2: Measurements configuration Figure 3: KBMF attenuation curve Insertion loss (dB) 0 50 Ω -10 TEST BOARD TG OUT RF IN KM1 Vg 50 Ω -20 -30 -40 1 10 100 F (MHz) 2/8 1000 KBMF 2. ESD PROTECTION The KBMFxxSC6 is particularly optimized to perform ESD protection. ESD protection is based on the use of device which clamps at: Voutput = VBR + Rd.IPP This protection function is splitted in 2 stages. As shown in figure 4, the ESD strikes are clamped by the first stage S1 and then its remaining overvoltage is applied to the second stage through the resistor R. Such a configuration makes the output voltage very low at the Voutput level. Figure 4: ESD clamping behavior Rg S1 Rd VPP ESD Surge VBR Rs S2 Rd Vinput Rload Voutput VBR KBMFxxSC6 Device to be protected To have a good approximation of the remaining voltages at both Vinput and Voutput stages, we give the typical dynamical resistance value Rd. By taking into account these following hypothesis : Rt>Rd, Rg>Rd and Rload>Rd, it gives these formulas: R g ⋅ V BR + R d ⋅ V g V input = -----------------------------------------------------Rg R s ⋅ V BR + R d ⋅ V input V output = ----------------------------------------------------------------Rt The results of the calculation done for VPP=8kV, Rg=330Ω (IEC 61000-4-2 standard), VBR=7V (typ.) and Rd = 1Ω (typ.) give: Vinput = 31.2 V Voutput = 7.8 V This confirms the very low remaining voltage across the device to be protected. It is also important to note that in this approximation the parasitic inductance effect was not taken into account. This could be few tenths of volts during few ns at the input side. This parasitic effect is not present at the output side due the low current involved after the resistance RS. The measurements done here after show very clearly (figure 6) the high efficiency of the ESD protection : - no influence of the parasitic inductances on output stage - Voutput clamping voltage very close to VBR (positive strike) and -VF (negative strike) 3/8 KBMF Figure 5: Measurement conditions ESD SURGE Vin KM1 16kV Air Discharge TEST BOARD Vout Figure 6: Remaining voltage at both stages S1 (Vinput) and S2 (Voutput) during ESD surge Positive surge Negative surge Please note that the KBMF01SC6 is not only acting for positive ESD surges but also for negative ones. For these kind of disturbances it clamps close to ground voltage as shown in the Negative Surge figure. 3. LATCH-UP PHENOMENA The early ageing and destruction of IC’s is often due to latch-up phenomena which is mainly induced by dV/dt. Thanks to its structure, the KBMF01SC6 provides a high immunity to latch-up phenomena by smoothing very fast edges. 4/8 KBMF 4. CROSSTALK BEHAVIOR Figure 7: Crosstalk phenomena RG1 Line 1 VG1 RL1 RG2 α1VG1 + β12VG2 Line 2 VG2 RL2 DRIVERS α2VG2 + β21VG1 RECEIVERS The crosstalk phenomena is due to the coupling between 2 lines. The coupling factor ( β12 or β21 ) increases when the gap across lines decreases, this is the reason why we provide crosstalk measurements for monolithic device to guarantee negligeable crosstalk between the lines. In the example above the expected signal on load RL2 is α2VG2, in fact the real voltage at this point has got an extra value β21VG1. This part of the VG1 signal represents the effect of the crosstalk phenomenon of the line 1 on the line 2. This phenomenon has to be taken into account when the drivers impose fast digital data or high frequency analog signals in the disturbing line. The perturbed line will be more affected if it works with low voltage signal or high load impedance (few kΩ). Figure 8: Analog Crosstalk measurements configuration Figure 9: Typical Analog Crosstalk measurement crosstalk (dB) 0 -20 50 Ω TEST BOARD TG OUT -40 RF IN KM1 Vg 50 Ω -60 -80 -100 -120 1 10 100 1,000 F (MHz) Figure 8 gives the measurement circuit for the analog crosstalk application. In figure 9, the curve shows the effect of the Data line on the CLK line. In usual frequency range of analog signals (up to 100MHz) the effect on disturbed line is less than -37dB. 5/8 KBMF Figure 10: Digital crosstalk measurements configuration +5V Figure 11:Digital crosstalk measurements +5V 74HC04 74HC04 Line 1 Square Pulse Generator 5KHz +5V VG1 KBMF 01SC6 Line 2 b21 VG1 Figure 10 shows the measurement circuit used to quantify the crosstalk effect in a classical digital application. Figure 11 shows that in such a condition signal from 0 to 5V and rise time of few ns, the impact on the other line is less than 50mV peak to peak (below the logic high threshold voltage). The measurements performed with falling edges gives the results within the same range. 5. APPLICATION EXAMPLE Figure 12: Implementation of KBMFxxSC6 in a typical application KDAT KCLK KBMF 01SC6 PS/2 Connector PS/2 Keyboard Vcc MDAT MCLK KBMF 01SC6 PS/2 Mouse Super I/O The KBMF01SC6 device could be used on PS/2 mouse or keyboard as indicated by figure 12. 6/8 KBMF Figure 13: SOT23-6L Package Mechanical Data DIMENSIONS REF. A2 b A1 L H Min. A D E Millimeters c e e Min. Typ. Max. A 0.90 0 A2 0.90 1.30 0.035 0.051 b 0.35 0.50 0.014 0.02 C 0.09 0.20 0.004 0.008 D 2.80 3.05 0.110 0.120 E 1.50 1.75 0.059 0.069 1.45 0.035 0.057 0.10 0.004 0 0.95 0.037 H 2.60 3.00 0.102 0.118 L 0.10 0.60 0.004 0.024 θ Figure 14: SOT23-6L Foot print dimensions (in millimeters) Max. A1 e θ Typ. Inches 10° 10° Table 4: Mechanical Specifications Lead plating Tin-lead Lead plating thickness 5µm min. 25µm max. Lead material Sn / Pb (70% to 90%Sn) Lead coplanarity 10µm max Body material Molded epoxy Flammability UL94V-0 0.60 1.20 3.50 2.30 0.95 1.10 Table 5: Ordering Information Ordering code Marking Package Weight Base qty Delivery mode KBMF01SC6 KM1 SOT23-6L 16.7 mg 3000 Tape & reel Table 6: Revision History Date Revision Feb-2003 1D 28-Oct-2004 2 Description of Changes Last update. SOT23-6L package dimensions change for reference “D” from 3.0 millimeters (0.118 inches) to 3.05 millimeters (0.120 inches). 7/8 KBMF Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners © 2004 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com 8/8