Ultra large bandwidth ESD protection

www.DataSheet4U.com HDMIULC6-4SC6 Ultra large bandwidth ESD protection Main applications ■ ■ ■ ■ ■ HDMI ports at 1.65 Gb/s and up to 3.2 Gb/s IEEE 1394a, b, or c up to 3.2 Gb/s USB 2.0 ports up to 480 Mb/s (Hi-Speed) Ethernet port: 10/100/1000 Mb/s Video line protection SOT23-6L (JEDEC MO178AB) Functional diagram I/O1 1 Description The HDMIULC6-4SC6 is a monolithic, application specific discrete device dedicated to ESD protection of the HDMI connection. It also offers the same high level of protection for IEEE 1394a and IEEE 1394b/c, USB 2.0, Ethernet links, and video lines. Its ultra high cutoff frequency (5.3 GHz) secures a high level of signal integrity. The device topology provides this integrity without compromising the complete protection of ICs against the most stringent ESD strikes. 6 I/O4 When used with an HDMI VBUS application, Pin 5 should not be connected to protect against backdrive current flow. I/O3 GND 2 5 I/O2 3 4 Benefits ■ Features ■ ■ ■ ■ ■ ■ ■ 4 line 15 kV ESD protection Protects VBUS when applicable Ultra high bandwidth - no inluence on signal rise and fall times - maximised number of signal harmonics Very low leakage current: 0.5 µA max. Fast response time compared with varistors SOT23-6L package RoHS compliant ESD standards compliance guaranteed at device level, hence greater immunity at system level ESD protection of VBUS when applicable. High efficiency due to low residual voltage when confronted by an ESD surge Minimized rise and fall times for maximum data integrity Consistent D+ / D- signal balance: – Ultra low impact on intra-, inter-pair skew – Matching high bit rate HDMI requirements and ready for future evolution Low PCB space occupation - 9 mm² maximum foot print Low leakage current for longer operation of battery powered devices Higher reliability offered by monolithic integration ■ ■ ■ ■ ■ ■ ■ Complies with these standards: ■ IEC 61000-4-2 level 4 – 15 kV air discharge – 8 kV (and up to 15 kV) contact discharge Order code Part Number HDMIULC6-4SC6 Marking DL46 July 2006 Rev 2 1/11 www.st.com Characteristics HDMIULC6-4SC6 1 Characteristics Table 1. Symbol VPP Tstg Tj TL Peak pulse voltage Storage temperature range Maximum junction temperature Lead solder temperature (10 seconds duration) Absolute ratings Parameter IEC 61000-4-2 air discharge IEC 61000-4-2 contact discharge MIL STD883C-Method 3015-6 Value ±15 ±15 ±25 -55 to +150 125 260 Unit kV °C °C °C Table 2. Symbol IRM VBR Electrical characteristics (Tamb = 25° C) Value Parameter Leakage current Breakdown voltage between VBUS and GND Test Conditions Min. VRM = 5 V IR = 1 mA IPP = 1 A, tp = 8/20 µs Any I/O pin to GND 6 12 17 1 0.6 0.015 VR = 0 V, F = 1 MHz VR = 0 V, F = 825 MHz Capacitance variation between I/O 0.42 0.3 0.007 0.5 pF pF Typ. Max 0.5 µA V V V Unit VCL Clamping voltage IPP = 5 A, tp = 8/20 µs Any I/O pin to GND Capacitance between I/O and GND VR = 0 V, F = 1 MHz VR = 0 V, F = 825 MHz Ci/o-GND Capacitance variation between I/O ∆Ci/o-GND and GND Ci/o-i/o ∆Ci/o-i/o Capacitance between I/O 2/11 HDMIULC6-4SC6 Characteristics Figure 1. Line capacitance versus line voltage (typical values) C(pF) Figure 2. Line capacitance versus frequency (typical values) C(pF) 1.0 F=825MHz Vosc=500mVRMS VBUS OPEN Tj =25 °C 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 CI/O - GND 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 Vosc=30mVRMS Tj =25°C VI-O/GND = 0V VBUS OPEN CI/O - GND Data line voltage (v) 0.1 0 CI/O - CI/O F(MHz) 1 10 100 1000 10000 Figure 3. Relative variation of leakage current versus junction temperature (typical values) Figure 4. Frequency response S21(db) Attenuation IRM[Tj] / IRM[Tj=25°C] 5 4 0 -2 3 2 -4 -6 Tj(°C) 1 25 50 75 100 125 -8 100.0k 1.0M 10.0M 100.0M 1.0G F(Hz) 3/11 Application examples HDMIULC6-4SC6 2 Application examples Figure 5. HDMI Digital single link application using HDMIULC6-4SC6 Host (Set Top Box, DVD player, PC) HDMI Tx0Tx0+ TMDS transmitter Rx0Rx0+ Display (TV, flat panel, monitor, projector) HDMI connectors TMDS receiver video video Tx1Multimedia controller audio Rx1Rx1+ Rx2Rx2+ Ctrl / status audio Tx1+ Tx2Tx2+ controller Ctrl / status HDMIULC6-4SC6 TCTC+ TMDS links CEC SCL Vcc 5V SDA HPD Control links HDMIULC6-4SC6 RCRC+ CEC SCL Vcc 5V SDA HPD Figure 6. T1/E1/Ethernet protection Tx SMP75-8 +VCC 100 nF 3 1 1 2 4 5 DATA TRANSCEIVER Rx SMP75-8 4/11 6 HDMIULC6-4SC6 Application examples 2.1 PCB layout considerations For HDMI applications, VCC should not be connected. In this case the capacitor C in Figure 7. is not needed. Figure 7. PCB layout considerations (VCC connection is application dependent) HDMI Connector Side D+1 D-1 GND D+2 D-2 1 VCC C = 100 nF HDMIULC6-4SC6 A differential impedance of 100 Ω must be respected in the layout. Both lines of the differential pair should have the same length. Figure 8. Footprint dimensions (in mm) 1.20 1.10 0.60 0.95 2.30 3.50 5/11 Technical information HDMIULC6-4SC6 3 3.1 Technical information Surge protection The HDMIULC6-4SC6 is particularly optimized to perform ESD surge protection based on the rail to rail topology. The clamping voltage VCL can be calculated as follows: VCL+ = VTRANSIL + VF for positive surges VCL- = - VF with: VF = VT + Rd.Ip (VF forward drop voltage) / (VT forward drop threshold voltage) and VTRANSIL = VBR + Rd_TRANSIL . IP for negative surges Calculation example We assume that the value of the dynamic resistance of the clamping diode is typically: Rd = 0.5 Ω and VT = 1.1 V. We assume that the value of the dynamic resisteance of the transil diode is typically Rd_TRANSIL = 0.5 Ω and VBR = 6.1 V For an IEC 61000-4-2 surge Level 4 (Contact Discharge: Vg= 8 kV, Rg= 330 Ω), VBUS = +5 V, and, in first approximation, we assume that: Ip = Vg / Rg = 24 A. We find: VCL+ = +31.2 V VCL- = -13.1 V Note: The calculations do not take into account phenomena due to parasitic inductances. 3.2 Surge protection application example If we consider that the connections from the pin VBUS to VCC, from I/O to data line, and from GND to PCB GND plane are two tracks 10 mm long and 0.5 mm wide, we can assume that the parasitic inductances, LVBUS, LI/O, and LGND, of these tracks are about 6 nH. So when an IEC 61000-4-2 surge occurs on the data line, due to the rise time of this spike (tr = 1 ns), the voltage VCL has an extra value equal to LI/O.dI/dt + LGND.dI/dt. The dI/dt is calculated as: dI/dt = Ip/tr = 24 A/ns for an IEC 61000-4-2 surge level 4 (contact discharge Vg = 8 kV, Rg = 330 Ω The over voltage due to the parasitic inductances is: LI/O.dI/dt = LGND.dI/dt = 6 x 24 = 144 V By taking into account the effect of these parasitic inductances due to unsuitable layout, the clamping voltage will be: VCL+ = +31.2 + 144 +144 = 319.2 V VCL- = -13.1 - 144 -144 = -301.1 V We can reduce as much as possible these phenomena with simple layout optimization. 6/11 HDMIULC6-4SC6 Technical information It’s the reason why some recommendations have to be followed (see Section 3.3: How to ensure good ESD protection). Figure 9. ESD behavior: parasitic phenomena due to unsuitable layout VCL+ VBUS Data line LI/O ESD surge on data line LI/O di L VBUS dt Vcc pin L I/O di di + L GND dt dt POSITIVE SURGE VF VTRANSIL I/O pin VCL VTRANSIL +VF t tr=1ns GND pin LGND LGND di dt -VF tr=1ns t VCL + = VTRANSIL + VF + L I/O VCL - = - VF - L I/O di di + L GND dt dt di di - L GND dt dt surge > 0 - L I/O surge < 0 di di - L GND dt dt NEGATIVE SURGE VTRANSIL = VBR + Rd.Ip VCL- 3.3 How to ensure good ESD protection While the HDMIULC6-4SC6 provides a high immunity to ESD surge, an efficient protection depends on the layout of the board. In the same way, with the rail to rail topology, the track from data lines to I/O pins, from VCC to VBUS pin, and from GND plane to GND pin must be as short as possible to avoid over voltages due to parasitic phenomena (see Figure 9 and Figure 10 for layout considerations). Figure 10. ESD behavior: layout optimization Figure 11. ESD behavior: measurement conditions ESD SURGE TEST BOARD IN OUT Unsuitable layout HDMIULC6- 4SC6 Vbus Optimized layout 7/11 Technical information HDMIULC6-4SC6 Figure 12. Remaining voltage after the HDMIULC6-4SC6 during positive ESD surge Figure 13. Remaining voltage after the HDMIULC6-4SC6 during negative ESD surge Note: The measurements have been done with the HDMIULC6-4SC6 in open circuit. IMPORTANT: An important precaution to take is to put the protection device as close as possible to the disturbance source (generally the connector). 3.4 Crosstalk behavior Figure 14. Crosstalk phenomena RG1 Line 1 α 1 VG1 + β12VG2 VG1 RG2 Line 2 RL1 VG2 RL2 α 2VG2 + β21VG1 DRIVERS 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, particularly in silicon dice. 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). 8/11 HDMIULC6-4SC6 Figure 15. Analog crosstalk measurements TEST BOARD NETWORK ANALYSER PORT 1 Technical information NETWORK ANALYSER PORT 2 Vbus Figure 15 gives the measurement circuit for the analog application. In usual frequency range of analog signals (up to 240 MHz) the effect on disturbed line is less than -45 dB (see Figure 16). Figure 16. Analog crosstalk results 0.00 dB - 30.00 - 60.00 - 90.00 F (Hz) - 120.00 100.0k