ISL8323, ISL8324, ISL8325 TM Data Sheet January 2002 Low-Voltage, Single Supply, Dual SPST Analog Switches Features The Intersil ISL8323–ISL8325 devices are precision, dual analog switches designed to operate from a single +2.7V to +12V supply. Targeted applications include battery powered equipment that benefit from the devices’ low power consumption (5µW), low leakage currents (100pA max), and fast switching speeds. Excellent RON matching and flatness maintain signal fidelity over the whole input range. The ISL8323/ISL8324/ISL8325 are dual single-pole/singlethrow (SPST) devices. The ISL8323 has two normally open (NO) switches; the ISL8324 has two normally closed (NC) switches; the ISL8325 has one NO and one NC switch and can be used as an SPDT. Table 1 summarizes the performance of this family. For higher performance, pin compatible versions, or SOT-23 packaged devices, see the ISL5120-23 data sheet. SW 1 / SW 2 ISL8323 ISL8324 ISL8325 2 2 2 NO / NO NC / NC NO / NC 175Ω 175Ω 175Ω 400 / 125ns 400 / 125ns 400 / 125ns 60Ω 60Ω 60Ω 150 / 100ns 150 / 100ns 150 / 100ns 3.3V RON (Max) 3.3V tON / tOFF (Max) 5V RON (Max) 5V tON / tOFF (Max) Packages • Drop-in Replacements for MAX323 - MAX325 in Single Supply Applications up to 12V. • ON Resistance (RON). . . . . . . . . . . . . . . . . . . . 60Ω (Max) • RON Matching Between Channels. . . . . . . . . . . . . 2Ω (Max) • Low Charge Injection . . . . . . . . . . . . . . . . . . . . . . 5pC (Max) • Single Supply Operation . . . . . . . . . . . . . . . . . +2.7V to +12V • Low Power Consumption (PD) . . . . . . . . . . . . . . . . . . . .<5µW • Low Leakage Current (Max at 85oC) . . . . . . . . . . . . . 5nA • Fast Switching Action - tON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150ns (Max) - tOFF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100ns (Max) • Guaranteed Break-Before-Make (ISL8325 only) • Minimum 2000V ESD Protection per Method 3015.7 • TTL, CMOS Compatible TABLE 1. SUMMARY OF FEATURES Number of Switches 8 Ld SOIC Applications • Battery Powered, Handheld, and Portable Equipment - Cellular/Mobile Phones - Pagers - Laptops, Notebooks, Palmtops • Communications Systems - Military Radios - PBX, PABX • Test Equipment - Ultrasound - Electrocardiograph Related Literature • Heads-Up Displays • Technical Brief TB363 Guidelines for Handling and Processing Moisture Sensitive Surface Mount Devices (SMDs) • Audio and Video Switching 1 FN6023 • Various Circuits - +3V/+5V DACs and ADCs - Sample and Hold Circuits - Digital Filters - Operational Amplifier Gain Switching Networks - High Frequency Analog Switching - High Speed Multiplexing - Integrator Reset Circuits CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a trademark of Intersil Americas Inc. Copyright © Intersil Americas Inc. 2002. All Rights Reserved ISL8323, ISL8324, ISL8325 Pinouts (Note 1) ISL8323 (SOIC) TOP VIEW ISL8324 (SOIC) TOP VIEW NO1 1 8 V+ NC1 1 8 V+ COM1 2 7 IN1 COM1 2 7 IN1 6 COM2 IN2 3 5 NO2 GND 4 6 COM2 IN2 3 5 NC2 GND 4 ISL8325 (SOIC) TOP VIEW NO1 1 8 V+ COM1 2 7 IN1 IN2 3 GND 4 6 COM2 5 NC2 NOTE: 1. Switches Shown for Logic “0” Input. Truth Table Ordering Information ISL8323 ISL8324 LOGIC SW 1,2 SW 1,2 SW 1 SW 2 0 OFF ON OFF ON 1 ON OFF ON OFF NOTE: ISL8325 Logic “0” ≤ 0.8V. Logic “1” ≥ 2.4V. Pin Descriptions PIN FUNCTION V+ System Power Supply Input (+2.7V to +12V) GND Ground Connection IN Digital Control Input COM Analog Switch Common Pin NO Analog Switch Normally Open Pin NC Analog Switch Normally Closed Pin 2 PART NO. (BRAND) TEMP. RANGE (oC) PACKAGE PKG. NO. ISL8323IB -40 to 85 8 Ld SOIC M8.15 ISL8323IB-T -40 to 85 8 Ld SOIC Tape and Reel M8.15 ISL8324IB -40 to 85 8 Ld SOIC M8.15 ISL8324IB-T -40 to 85 8 Ld SOIC Tape and Reel M8.15 ISL8325IB -40 to 85 8 Ld SOIC M8.15 ISL8325IB-T -40 to 85 8 Ld SOIC Tape and Reel M8.15 ISL8323, ISL8324, ISL8325 Absolute Maximum Ratings Thermal Information V+ to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to15V Input Voltages IN, NO, NC, COM (Note 2) . . . . . . . . . . . . . . -0.3 to ((V+) + 0.3V) Continuous Current (NO, NC, or COM) . . . . . . . . . . . . . . . . . . 30mA Peak Current NO, NC, or COM (Pulsed 1ms, 10% Duty Cycle, Max) . . . . . . . . . . . . . . . . . 100mA ESD Rating (Per MIL-STD-883 Method 3015). . . . . . . . . . . . . .>2kV Thermal Resistance (Typical, Note 3) θJA (oC/W) 8 LD SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . 170 Maximum Junction Temperature (Plastic Package) . . . . . . . . 150oC Moisture Sensitivity (See Technical Brief TB363) All Packages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Level 1 Maximum Storage Temperature Range . . . . . . . . . . . . -65oC to 150oC Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300oC (SOIC - Lead Tips Only) Operating Conditions Temperature Range ISL832XIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40oC to 85oC CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTES: 2. Signals on NC, NO, COM, or IN exceeding V+ or GND are clamped by internal diodes. Limit forward diode current to maximum current ratings. 3. θJA is measured with the component mounted on a low effective thermal conductivity test board in free air. See Tech Brief TB379 for details. Electrical Specifications - 5V Supply PARAMETER Test Conditions: V+ = +4.5V to +5.5V, GND = 0V, VINH = 2.4V, VINL = 0.8V (Note 4), Unless Otherwise Specified TEST CONDITIONS TEMP (oC) MIN (NOTE 5) TYP Full 0 - V+ V 25 - - 60 Ω Full - - 75 Ω MAX (NOTE 5) UNITS ANALOG SWITCH CHARACTERISTICS Analog Signal Range, VANALOG ON Resistance, RON V+ = 4.5V, ICOM = 1.0mA, VNO or VNC = 3.5V, See Figure 5 RON Matching Between Channels, ∆RON V+ = 5V, ICOM = 1.0mA, VNO or VNC= 3V RON Flatness, RFLAT(ON) 25 - 0.8 2 Ω Full - - 4 Ω V+ = 5V, ICOM = 1.0mA, VNO or VNC = 1V, 2V, 3V Full - 7 8 Ω NO or NC OFF Leakage Current, INO(OFF) or INC(OFF) V+ = 5.5V, VCOM = 1V, 4.5V, VNO or VNC = 4.5V, 1V, Note 6 25 -0.1 - 0.1 nA Full -5 - 5 nA COM OFF Leakage Current, ICOM(OFF) V+ = 5.5V, VCOM = 4.5V, 1V, VNO or VNC = 1V, 4.5V, Note 6 25 -0.1 - 0.1 nA Full -5 - 5 nA COM ON Leakage Current, ICOM(ON) V+ = 5.5V, VCOM = 5V, or VNO or VNC = 5V, Note 6 25 -0.2 - 0.2 nA Full -10 - 10 nA 25 - - 150 ns Full - - 240 ns 25 - - 100 ns DYNAMIC CHARACTERISTICS Turn-ON Time, tON VNO or VNC = 3V, RL =1kΩ , CL = 35pF, VIN = 0 to 3V, See Figure 1 Turn-OFF Time, tOFF VNO or VNC = 3V, RL =1kΩ , CL = 35pF, VIN = 0 to 3V, See Figure 1 Full - - 150 ns Break-Before-Make Time Delay (ISL8325), tD RL = 300Ω , CL = 35pF, VNO = VNC = 3V, VIN = 0 to 3V, See Figure 3 Full 2 10 - ns Charge Injection, Q CL = 1.0nF, VG = 0V, RG = 0Ω, See Figure 2 25 - - 5 pC OFF Isolation RL = 50Ω, CL = 5pF, f = 1MHz, See Figure 4 25 - 72 - dB Crosstalk (Channel-to-Channel) RL = 50Ω, CL = 5pF, f = 1MHz, See Figure 6 25 - -85 - dB NO or NC OFF Capacitance, COFF f = 1MHz, VNO or VNC = VCOM = 0V, See Figure 7 25 - 9 - pF COM OFF Capacitance, CCOM(OFF) f = 1MHz, VNO or VNC = VCOM = 0V, See Figure 7 25 - 9 - pF COM ON Capacitance, CCOM(ON) f = 1MHz, VNO or VNC = VCOM = 0V, See Figure 7 25 - 22 - pF Full 2.7 Full -1 POWER SUPPLY CHARACTERISTICS Power Supply Range Positive Supply Current, I+ V+ = 5.5V, VIN = 0V or V+, all channels on or off 3 0.0001 12 V 1 µA ISL8323, ISL8324, ISL8325 Electrical Specifications - 5V Supply PARAMETER Test Conditions: V+ = +4.5V to +5.5V, GND = 0V, VINH = 2.4V, VINL = 0.8V (Note 4), Unless Otherwise Specified (Continued) TEST CONDITIONS TEMP (oC) MIN (NOTE 5) TYP MAX (NOTE 5) UNITS DIGITAL INPUT CHARACTERISTICS Input Voltage Low, VINL Full - - 0.8 V Input Voltage High, VINH Full 2.4 - - V NOTES: 4. VIN = input voltage to perform proper function. 5. The algebraic convention, whereby the most negative value is a minimum and the most positive a maximum, is used in this data sheet. 6. Leakage parameter is 100% tested at high temp, and guaranteed by correlation at 25oC. Electrical Specifications - 3.3V Supply PARAMETER Test Conditions: V+ = +3.0V to +3.6V, GND = 0V, VINH = 2.4V, VINL = 0.8V (Note 4), Unless Otherwise Specified TEST CONDITIONS TEMP (oC) MIN (NOTE 5) TYP MAX (NOTE 5) UNITS Full 0 - V+ V 25 - - 175 Ω Full - - 275 Ω 25 - - 400 ns 500 ns - - 125 ns ANALOG SWITCH CHARACTERISTICS Analog Signal Range, VANALOG ON Resistance, RON V+ = 3V, ICOM = 1.0mA, VNO or VNC = 1.5V DYNAMIC CHARACTERISTICS Turn-ON Time, tON VNO or VNC = 1.5V, RL =1kΩ, CL = 35pF, VIN = 0 to 3V Turn-OFF Time, tOFF VNO or VNC = 1.5V, RL =1kΩ, CL = 35pF, VIN = 0 to 3V Full - - 175 ns Break-Before-Make Time Delay (ISL8325), tD RL = 300Ω, CL = 35pF, VNO or VNC = 1.5V, VIN = 0 to 3V Full 2 - - ns Charge Injection, Q CL = 1.0nF, VG = 0V, RG = 0Ω 25 - - 5 pC Full -1 - 1 µA Full 25 POWER SUPPLY CHARACTERISTICS Positive Supply Current, I+ V+ = 3.6V, VIN = 0V or V+, all channels on or off 4 ISL8323, ISL8324, ISL8325 Test Circuits and Waveforms 3V LOGIC INPUT V+ tr < 20ns tf < 20ns 50% 0V tOFF VOUT NO or NC SWITCH INPUT SWITCH INPUT VNO COM VOUT IN 90% SWITCH OUTPUT C 90% LOGIC INPUT 0V CL 35pF RL 1kΩ GND tON Logic input waveform is inverted for switches that have the opposite logic sense. Repeat test for all switches. CL includes fixture and stray capacitance. RL V OUT = V (NO or NC) -----------------------------R L + R ( ON ) FIGURE 1A. MEASUREMENT POINTS FIGURE 1B. TEST CIRCUIT FIGURE 1. SWITCHING TIMES V+ SWITCH OUTPUT VOUT ∆VOUT RG C VOUT COM NO or NC V+ LOGIC INPUT ON ON VG OFF GND IN 0V CL LOGIC INPUT Q = ∆VOUT x CL FIGURE 2A. MEASUREMENT POINTS FIGURE 2B. TEST CIRCUIT FIGURE 2. CHARGE INJECTION V+ C 3V LOGIC INPUT 0V VOUT1 NO1 VNX COM1 VOUT2 RL1 300Ω NC2 SWITCH OUTPUT VOUT1 COM2 90% IN1 0V RL2 300Ω IN2 SWITCH OUTPUT VOUT2 90% 0V tD LOGIC INPUT CL2 35pF GND tD CL includes fixture and stray capacitance. FIGURE 3A. MEASUREMENT POINTS (ISL8325 ONLY) FIGURE 3B. TEST CIRCUIT (ISL8325 ONLY) FIGURE 3. BREAK-BEFORE-MAKE TIME 5 CL1 35pF ISL8323, ISL8324, ISL8325 Test Circuits and Waveforms (Continued) V+ V+ C C RON = V1/1mA SIGNAL GENERATOR NO or NC NO or NC VNX INX 0V or 2.4V 1mA COM ANALYZER IN V1 0.8V or 2.4V COM GND GND RL FIGURE 5. RON TEST CIRCUIT FIGURE 4. OFF ISOLATION TEST CIRCUIT V+ C V+ C SIGNAL GENERATOR NO1 or NC1 COM1 50Ω NO or NC IN1 0V or 2.4V COM2 ANALYZER INX IN2 0V or 2.4V NO2 or NC2 GND 0V or 2.4V IMPEDANCE ANALYZER COM NC GND RL FIGURE 6. CROSSTALK TEST CIRCUIT 6 FIGURE 7. CAPACITANCE TEST CIRCUIT ISL8323, ISL8324, ISL8325 Detailed Description Power-Supply Considerations The ISL8323–ISL8325 dual analog switches offer precise switching capability from a single 2.7V to 12V supply with low on-resistance and high speed operation. The devices are especially well suited to portable battery powered equipment thanks to the low operating supply voltage (2.7V), low power consumption (5µW), low leakage currents (100pA max), and the small SOIC packaging. High frequency applications also benefit from the wide bandwidth, and the very high off isolation and crosstalk rejection. The ISL832X construction is typical of most CMOS analog switches, except that they have only two supply pins: V+ and GND. V+ and GND drive the internal CMOS switches and set their analog voltage limits. Unlike switches with a 13V maximum supply voltage, the ISL832X 15V maximum supply voltage provides plenty of room for the 10% tolerance of 12V supplies, as well as room for overshoot and noise spikes. Supply Sequencing And Overvoltage Protection With any CMOS device, proper power supply sequencing is required to protect the device from excessive input currents which might permanently damage the IC. All I/O pins contain ESD protection diodes from the pin to V+ and to GND (see Figure 8). To prevent forward biasing these diodes, V+ must be applied before any input signals, and input signal voltages must remain between V+ and GND. If these conditions cannot be guaranteed, then one of the following two protection methods should be employed. Logic inputs can easily be protected by adding a 1kΩ resistor in series with the input (see Figure 8). The resistor limits the input current below the threshold that produces permanent damage, and the sub-microamp input current produces an insignificant voltage drop during normal operation. Adding a series resistor to the switch input defeats the purpose of using a low RON switch, so two small signal diodes can be added in series with the supply pins to provide overvoltage protection for all pins (see Figure 8). These additional diodes limit the analog signal from 1V below V+ to 1V above GND. The low leakage current performance is unaffected by this approach, but the switch resistance may increase, especially at low supply voltages. OPTIONAL PROTECTION DIODE V+ OPTIONAL PROTECTION RESISTOR INX V NO or NC VCOM GND OPTIONAL PROTECTION DIODE FIGURE 8. OVERVOLTAGE PROTECTION 7 The minimum recommended supply voltage is 2.7V. It is important to note that the input signal range, switching times, and on-resistance degrade at lower supply voltages. Refer to the electrical specification tables and Typical Performance curves for details. V+ and GND also power the internal logic and level shifters. The level shifters convert the logic levels to switched V+ and GND signals to drive the analog switch gate terminals. This family of switches cannot be operated with bipolar supplies, because the input switching point becomes negative in this configuration. Logic-Level Thresholds This switch family is TTL compatible (0.8V and 2.4V) over a supply range of 3V to 11V (see Figure 12). At 12V the VIH level is about 2.5V. This is still below the TTL guaranteed high output minimum level of 2.8V, but noise margin is reduced. For best results with a 12V supply, use a logic family the provides a VOH greater than 3V. The digital input stages draw supply current whenever the digital input voltage is not at one of the supply rails. Driving the digital input signals from GND to V+ with a fast transition time minimizes power dissipation. Leakage Considerations Reverse ESD protection diodes are internally connected between each analog-signal pin and both V+ and GND. One of these diodes conducts if any analog signal exceeds V+ or GND. Virtually all the analog leakage current comes from the ESD diodes to V+ or GND. Although the ESD diodes on a given signal pin are identical and therefore fairly well balanced, they are reverse biased differently. Each is biased by either V+ or GND and the analog signal. This means their leakages will vary as the signal varies. The difference in the two diode leakages to the V+ and GND pins constitutes the analogsignal-path leakage current. All analog leakage current flows between each pin and one of the supply terminals, not to the other switch terminal. This is why both sides of a given switch can show leakage currents of the same or opposite polarity. There is no connection between the analog-signal paths and V+ or GND. ISL8323, ISL8324, ISL8325 Typical Performance Curves TA = 25oC, Unless Otherwise Specified 45 0.5 0.4 0.3 V+ = 3.3V ICOM = 1mA 40 35 0.2 30 85oC 25 25oC 20 -40oC 15 30 25 ∆RON (Ω) RON (Ω) V+ = 3.3V ICOM = 1mA 25oC V+ = 5V 85oC 25oC -40oC 20 15 10 20 85oC 15 V+ = 12V 25oC 85oC 0.1 0 0.25 0.2 0.15 V+ = 5V 25oC 0.1 -40oC 5 0 V+ = 12V 25oC -40oC 0.05 -40oC 85oC 85oC 0.05 0 0.15 0.1 10 -40oC 85oC 25oC -40oC 0 4 2 6 VCOM (V) 8 10 0 12 4 2 6 VCOM (V) 8 10 12 FIGURE 10. RON MATCH vs SWITCH VOLTAGE FIGURE 9. ON RESISTANCE vs SWITCH VOLTAGE 3.0 60 50 2.5 40 VINH AND VINL (V) VINH Q (pC) 30 20 V+ = 5V V+ = 12V 10 V+ = 3.3V 0 -40oC 2.0 85oC 25oC 1.5 85oC -40oC 25oC 1.0 -10 VINL 85oC -20 2 0 4 6 VCOM (V) 8 10 12 0.5 3 2 FIGURE 11. CHARGE INJECTION vs SWITCH VOLTAGE 4 6 5 7 8 V+ (V) 9 10 11 12 13 FIGURE 12. DIGITAL SWITCHING POINT vs SUPPLY VOLTAGE 100 35 VCOM = (V+) - 1V 90 VCOM = (V+) - 1V RL = 1kΩ RL = 1kΩ 80 30 85oC tOFF (ns) tON (ns) 70 60 85oC 25 50 -40oC -40oC 40 20 -40oC 25oC 30 25oC 20 15 2 3 4 5 6 7 V+ (V) 8 9 10 11 FIGURE 13. TURN - ON TIME vs SUPPLY VOLTAGE 8 12 2 3 4 5 6 7 V+ (V) 8 9 10 11 FIGURE 14. TURN - OFF TIME vs SUPPLY VOLTAGE 12 ISL8323, ISL8324, ISL8325 Die Characteristics PASSIVATION: DIE DIMENSIONS: ISL832X: 54 mils x 28 mils (1370µm x 710µm) Type: Silox Thickness: 13kÅ TRANSISTOR COUNT: ISL8323: 66 ISL8324: 66 ISL8325: 66 METALLIZATION: Type: Metal 1: AISi(1%) Thickness: Metal 1: 8kÅ Type: Metal 2: AISi (1%) Thickness: Metal 2: 10kÅ PROCESS: Si Gate CMOS SUBSTRATE POTENTIAL (POWERED UP): GND 9 ISL8323, ISL8324, ISL8325 Small Outline Plastic Packages (SOIC) M8.15 (JEDEC MS-012-AA ISSUE C) N INDEX AREA 0.25(0.010) M H 8 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE B M E INCHES -B- 1 2 SYMBOL 3 L SEATING PLANE -A- h x 45o A D -C- µα e A1 B 0.25(0.010) M C C A M B S NOTES: 1. Symbols are defined in the “MO Series Symbol List” in Section 2.2 of Publication Number 95. 2. Dimensioning and tolerancing per ANSI Y14.5M-1982. 3. Dimension “D” does not include mold flash, protrusions or gate burrs. Mold flash, protrusion and gate burrs shall not exceed 0.15mm (0.006 inch) per side. 4. Dimension “E” does not include interlead flash or protrusions. Interlead flash and protrusions shall not exceed 0.25mm (0.010 inch) per side. 5. The chamfer on the body is optional. If it is not present, a visual index feature must be located within the crosshatched area. 6. “L” is the length of terminal for soldering to a substrate. 7. “N” is the number of terminal positions. 8. Terminal numbers are shown for reference only. 9. The lead width “B”, as measured 0.36mm (0.014 inch) or greater above the seating plane, shall not exceed a maximum value of 0.61mm (0.024 inch). 10. Controlling dimension: MILLIMETER. Converted inch dimensions are not necessarily exact. MAX MILLIMETERS MIN MAX NOTES A 0.0532 0.0688 1.35 1.75 - A1 0.0040 0.0098 0.10 0.25 - B 0.013 0.020 0.33 0.51 9 C 0.0075 0.0098 0.19 0.25 - D 0.1890 0.1968 4.80 5.00 3 E 0.1497 0.1574 3.80 4.00 4 e 0.10(0.004) MIN 0.050 BSC 1.27 BSC - H 0.2284 0.2440 5.80 6.20 - h 0.0099 0.0196 0.25 0.50 5 L 0.016 0.050 0.40 1.27 6 8o 0o N α 8 0o 8 7 8o Rev. 0 12/93 All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements 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 Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com Sales Office Headquarters NORTH AMERICA Intersil Corporation 7585 Irvine Center Drive Suite 100 Irvine, CA 92618 TEL: (949) 341-7000 FAX: (949) 341-7123 Intersil Corporation 2401 Palm Bay Rd. Palm Bay, FL 32905 TEL: (321) 724-7000 FAX: (321) 724-7946 10 EUROPE Intersil Europe Sarl Ave. William Graisse, 3 1006 Lausanne Switzerland TEL: +41 21 6140560 FAX: +41 21 6140579 ASIA Intersil Corporation Unit 1804 18/F Guangdong Water Building 83 Austin Road TST, Kowloon Hong Kong TEL: +852 2723 6339 FAX: +852 2730 1433