APW7134 Dual 1.5MHz, 600mA Synchronous Step-Down Converter Features • • • • • • • • • • • • • General Description 600mA Output Current on Each Channel The APW7134 contains two independent 1.5MHz con- 2.5V to 5.5V Input Voltage Range stant frequency, current mode, PWM step-down converters. Each converter integrates a main switch 1.5MHz Constant Frequency Operation and a synchronous rectifier for high efficiency without Low Dropout Operation at 100% Duty Cycle an external Schottky diode. The APW7134 is ideal for Synchronous Topology powering portable equipment that runs from a single cell Lithium-Ion (Li+) battery. Each converter can sup- 0.6V Low Reference Voltage ply 600mA of load current from a 2.5V to 5.5V input Typically 0.1 µA Shutdown Current voltage. The output voltage can be regulated as low as Current Mode Operation 0.6V. The APW7134 can also run at 100% duty cycle Over Temperature Protection for low dropout applications. Over Current Protection Up to 94% Efficiency Pinouts Internally Compensated Lead Free Available (RoHS Compliant) APW7134 (Top View) DFN-10 (3mm x 3mm) Applications • • TV Tuner/Box EN1 1 FB1 2 9 GND1 IN2 3 8 IN1 GND2 4 7 FB2 SW2 Portable Instrument 5 10 SW1 6 EN2 Exposed pad on backside ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and advise customers to obtain the latest version of relevant information to verify before placing orders. Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 1 www.anpec.com.tw APW7134 Ordering and Marking Information APW7134 Package Code QA : DFN-10 Temp. Range I : -40 to 85° C Handling Code TU : Tube TR : Tape & Reel Lead Free Code L : Lead Free Device Blank : Original Device Lead Free Code Handling Code Temp. Range Package Code APW7134 QA: APW 7134 XXXXX XXXXX - Date Code Note: ANPEC lead-free products contain molding compounds/die attach materials and 100% matte tin plate termination finish; which are fully compliant with RoHS and compatible with both SnPb and lead-free soldiering operations. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J STD-020C for MSL classification at lead-free peak reflow temperature. Block Diagram Slop Compensation Σ ICOMP Oscillator IN1/ IN2 Frequency Shift RSENSE FB1/ FB2 EA QSENSE 0.6V QP R Q S Q EN1/ EN2 SW1/ SW2 Control Logic QN Shutdown IRCMP GND1/ GND2 Diagram Represents 1/2 of the APW7134 Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 2 www.anpec.com.tw APW7134 Pin Description Pin No. Name 1 EN1 2 FB1 3 4 IN2 GND2 5 SW2 6 EN2 7 FB2 8 9 IN1 GND1 10 SW1 Function Channel 1 Enable Control Input. Drive EN1 above 1.5V to turn on the Channel 1. Drive EN1 below 0.3V to turn it off. In shutdown situation, all functions are disabled to decrease the supply current below 1µA.There is no pull high or pull low ability inside. Channel 1 Feedback Input. Connect FB1 to the center point of the external resistor divider. The feedback voltage is 0.6V. Channel 2 Supply Input. Bypass to GND with a 4.7µF or greater ceramic capacitor. Ground 2. Connected the exposed pad to GND2. Channel 2 Power Switch Output. Inductor connection to drains of the internal PMOSFET and NMOSFET switches. Channel 2 Enable Control Input. Drive EN2 above 1.5V to turn on the Channel 2. Drive EN2 below 0.3V to turn it off. In shutdown situation, all functions are disabled to decrease the supply current below 1µA.There is no pull high or pull low ability inside. Channel 2 Feedback Input. Connect FB2 to the center point of the external resistor divider. The feedback voltage is 0.6V. Channel 1 Supply Input. Bypass to GND with a 4.7µF or greater ceramic capacitor. Ground 1. Connected the exposed pad to GND1. Channel 1 Power Switch Output. Inductor connection to drains of the internal PMOSFET and NMOSFET switches. Absolute Maximum Ratings Symbol VIN1/IN2 VFB1/FB2 VEN1/EN2 VSW1/SW2 ISW_PEAK TJ TSTG TSDR VESD Parameter Input Supply Voltage (IN1/IN2 to GND1/GND2) Voltage on FB1 and FB2 Voltage on EN1 and EN2 Voltage on SW1 and SW2 Peak SW Current Junction temperature Storage temperature Soldering temperature, 10 seconds Minimum ESD rating (Human body mode) (Note 1) Value -0.3 ~ 6 -0.3 ~ VIN1/IN2+0.3 -0.3 ~ VIN1/IN2+0.3 -0.3 ~ VIN1/IN2+0.3 1.3 150 -65 ~ 150 300 ±3 Unit V V V V A °C °C °C KV Value 50 Unit °C/W Note 1: The device is ESD sensitive. Handling precautions are recommended. Thermal Characteristics Symbol θJA Parameter Junction-to-Ambient Resistance in free air (Note 2) Note 2: θJA is measured on approximately 1¨ square of 1 oz copper. Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 3 www.anpec.com.tw APW7134 Recommended Operating Conditions (Note 3) Symbol VIN1/IN2 R2/R4 IOUT TA TJ Parameter Input Supply Voltage (IN1/IN2 to GND1/GND2) Feedback Resistance (Note 3) Output Current Operating ambient temperature Operating junction temperature Value Typ. Min. 2.5 -40 -40 Max. 5.5 200 600 85 125 Unit V KΩ mA °C °C Note 3: Please refer to the typical application circuit. Electrical Characteristics The * denotes the specifications that apply over TA = -40°C ~ 85°C, otherwise specifications are at TA=25°C Symbol Parameter APW7134 Test Conditions Min. VIN1/IN2 Each Converter Input Voltage Range IFB1/FB2 Each Converter Feedback current VFB1/FB2 ∆VFB1/FB2 VFB1/FB2=0.6V Each Converter Regulated Feedback Voltage Each Converter Reference voltage Line regulation VIN1/IN2=2.5V to 5.5V Typ. Unit Max. * 2.5 5.5 V * -30 30 nA * 0.588 0.6 0.612 V 0.04 0.4 %/V 1 1.25 A * VIN1/IN2=3V,VFB=0.5V IPK Each Converter Peak Inductor Current or VOUT=90%, 0.75 Duty cycle < 35% VLOADR Each Converter Load Regulation IQ Each Converter Quiescent Current Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 0.5 Duty Cycle=0; VFB=1.5V 4 300 % 400 µA www.anpec.com.tw APW7134 Electrical Characteristics (Cont.) The * denotes the specifications that apply over TA = -40°C ~ 85°C, otherwise specifications are at TA=25°C Symbol Parameter APW7134 Test Conditions Min. IQ-SD fOSC Each Converter Quiescent Current in Shutdown Each Converter Oscillator Frequency VFB=0.6V fOSC_FFB Each Converter Frequency Foldback RDS-P RDS-N ILSW VEN1/EN2=0V,VIN=4.2V Each Converter On Resistance of PMOSFET Each Converter On Resistance of NMOSFET 1.2 Max. 0.1 1 µA 1.5 1.8 MHz VFB=0V 210 ISW=100mA 0.4 0.5 Ω ISW=-100mA 0.35 0.45 Ω ±0.01 ±1 µA 1 1.5 V ±0.01 ±1 µA VEN1=0V,VSW=0V Each Converter SW Leakage Current Unit Typ. or 5V,VIN=5V VEN1/EN2 Each Converter Enable Threashold * IEN1/EN2 EN1/EN2 Leakage Current * 0.3 KHz Application Circuit VIN1/IN2 CIN1 4.7uF L1 2.2uH R1 300KΩ COUT1 10uF R2 150K Ω 3 IN1 1 OFF ON VOUT1 1.8V 600mA 8 R5 100K Ω 10 2 R6 100K Ω IN2 EN1 EN2 SW1 SW2 APW7134 FB1 FB2 GND1 GND2 9 4 6 5 7 CIN2 4.7uF OFF ON L2 2.2uH VOUT2 3.3V 600mA R3 680K Ω R4 150K Ω COUT2 10uF Typical Application Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 5 www.anpec.com.tw APW7134 Typical Operating Characteristics Reference Voltage Oscillator Frequency 1800 0.610 1700 VIN=5.5V 0.605 VIN=2.5V Frequency (KHz) Reference Voltage (V) 0.615 0.600 0.595 VIN=3.6V 1600 1500 1400 1300 0.590 1200 0.585 -50 -25 0 25 50 75 100 -50 125 -25 Temperature (o C) 0 25 50 75 100 125 100 125 Temperature (o C) Oscillator Frequency vs Supply Voltage RDS(ON) vs Temperature 700 1800 VIN=2.7V TA=25o C VIN=3.6V 600 1700 ON Resistance (mΩ) Frequency (KHz) VIN=4.2V 1600 1500 1400 1300 500 400 300 200 NMOS PMOS 100 0 1200 2 3 4 5 -50 6 0 25 50 75 Temperature (o C) Supply Voltage (V) Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 -25 6 www.anpec.com.tw APW7134 Typical Operating Characteristics (Cont.) RDS(ON) vs Input Voltage Efficiency vs Output Current 600 100 VOUT=1.2V TA=25o C 90 PMOS VIN=2.7V 80 70 400 Efficiency (%) ON Resistance (mΩ) 500 300 NMOS 200 60 50 40 VIN=3.6V 30 20 100 VIN=4.2V 10 0 0 0 1 2 3 4 5 0.1 6 Input Voltage (V) 10.0 100.0 1000.0 Output Current (mA) Efficiency vs Output Current Efficiency vs Output Current 100 100 VOUT=1.5V TA=25o C 90 VIN=2.7V VOUT=2.5V TA=25o C 90 80 80 70 70 VIN=3.6V Efficiency (%) Efficiency (%) 1.0 60 50 40 30 VIN=4.2V VIN=3.6V 60 50 40 30 20 20 10 10 0 VIN=4.2V VIN=2.7V 0 0.1 1.0 10.0 100.0 1000.0 0.1 Output Current (mA) Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 1.0 10.0 100.0 1000.0 Output Current (mA) 7 www.anpec.com.tw APW7134 Typical Operating Characteristics (Cont.) Efficiency vs Input Voltage 100 100 95 95 90 85 IOUT=100mA 90 IOUT=100mA 85 IOUT=600mA Efficiency (%) Efficiency (%) Efficiency vs Input Voltage 80 75 IOUT=10mA 70 65 IOUT=600mA 80 75 IOUT=10mA 70 65 60 60 VOUT=1.5V TA=25o C 55 VOUT=1.8V TA=25o C 55 50 50 2 3 4 5 2 6 Input Voltage (V) 4 5 6 Input Voltage (V) Efficiency vs Input Voltage Dynamic Supply Current vs Supply Voltage 100 400 95 380 Dynamic Supply Current (µA) IOUT=100mA 90 85 Efficiency (%) 3 IOUT=600mA 80 75 IOUT=10mA 70 65 60 VOUT=2.5V TA=25o C 55 50 360 340 320 300 280 260 240 220 200 2 3 4 5 6 2 Input Voltage (V) Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 3 4 5 6 Supply Voltage (V) 8 www.anpec.com.tw APW7134 Typical Operating Characteristics (Cont.) NMOSFET Leakage vs Temperature 300 800 250 750 NMOSFET Leakage(nA) PMOSFET Leakag(nA) PMOSFET Leakage vs Temperature 200 VIN=5.5V 150 100 50 0 700 650 VIN=5.5V 600 550 500 -50 -25 0 25 50 75 100 125 -50 -25 Temperature (o C) 0 25 50 75 100 125 Temperature (o C) Functional Descriptions Pulse Skipping Mode Operation Main Control Loop The APW7134 has dual independent constant fre- At light load with a relative small inductance, the quency current mode PWM step-down converters. All inductor current may reach zero. The internal power the main and synchronous switches are internal to NMOSFET is turned off by the current reversal reduce the external components. During normal comparator, IRCMP, and the switching voltage will ring. operation, the internal PMOSFET is turned on, but is This is discontinuous mode operation, and is normal turned off when the inductor current at the input of behavior for the switching regulator. At very light load, ICOMP to reset the RS latch. The load current increases, the APW7134 will automatically skip some pulses in it causes a slight decrease in the feedback voltage, the pulse skipping mode to maintain the output which in turn, causes the EA’s output voltage to in- regulation. The skipping process modulates smoothly crease until the average inductor current matches the depend on the load. new load current. While the internal power PMOSFET Short Circuit Protection is off, the internal power NMOSFET is turned on until In the short circuit situation, the output voltage is the inductor current starts to reverse, as indicated by the current reversal comparator IRCMP, or the begin- almost zero volts. Output current is limited by the ning of next cycle. When the NMOSFET is turned off ICOMP to prevent the damage of electrical circuit. In the by IRCMP, it operates in the discontinuous conduction normal operation, the two straight line of the inductor current ripple have the same height, it means the mode. volts-seconds product is the same. When the short circuit operation occurs, the output voltage down to Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 9 www.anpec.com.tw APW7134 Functional Descriptions (Cont.) Short Circuit Protection Cont. Slope Compensation zero leads to the voltage across the inductor maximum Slope compensation provides stability in constant in the on period and the voltage across the inductor frequency current mode architecture by preventing minimum in the off period. In order to maintain the sub-harmonic oscillations at high duty cycle. It is volts-seconds balance, the off-time must be extended accomplished internally by adding a compensating to prevent the inductor current run away. Frequency ramp to the inductor current signal at duty cycle in decay will extend the switching period to provide more excess of 40%. Normally, this results in a reduction times to the off-period, then the inductor current have of maximum inductor peak current for duty cycles to restrict to protect the electrical circuit in the short greater than 40%. In the APW7134, the reduction of situation. inductor peak current recovered by a special skill at high duty ratio. This allow the maximum inductor peak Dropout Operation current maintain a constant level through all duty ratio. An important detail to remember is that on resistance of PMOSFET switch will increase at low input supply voltage. Therefore, the user should calculate the power dissipation when the APW7134 is used at 100% duty cycle with low input voltage. Application Description Inductor Selection selecting a low DC resistance inductor is a helpful way. Due to the high switching frequency as 1.5MHz, the Another important parameter is the DC current rating inductor value of the application field of APW7134 is of the inductor. The minimum value of DC current usually from 1µH to 4.7µH. The criterion to selecting a rating equals the full load value of 600mA, plus the suitable inductor is dependent on the worst current half of the worst current ripple, 120mA. Choose ripple throughout the inductor. The worst current ripple inductors with suitable DC current rating to ensure defines as 40% of the fully load capability. In the the inductors don’t operate in the saturation. APW7134 applications, the worst value of current ripple is 240mA, the 40% of 600mA. Evaluate L by Input Capacitor Selection equation (1): L = (V IN The input capacitor must be able to support the − V OUT V IN ) ⋅ V OUT ⋅ 1 ∆ IL ⋅ f S maximum input operating voltage and maximum RMS input current. The Buck converter absorbs current from (1) input in pulses. where fS is the switching frequency of APW7134 and ∆IL is the value of the worst current ripple, it can be any value of current ripple that smaller than the worst value you can accept. In order to perform high efficiency, Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 10 www.anpec.com.tw APW7134 Application Description (Cont.) Observe the waveform of I(CIN),the RMS value of I(CIN) is Input Capacitor Selection Cont. I(CIN ) = I(Q1) ] ( − IIN ) ⋅ D + IIN ⋅ 1− D 2 OUT 2 ) 2 (2) Replace D and IIN by following relation: I(CIN) IIN [(I Q1 L VIN CIN D= I(L) Q2 I(COUT) COUT IOUT VOUT VIN (3) (4) IIN = D ⋅ IOUT The RMS value of input capacitor current equal: PWM I(C IN ) = IOUT ⋅ D(1 − D ) ) (5) When D=0.5 the RMS current of input capacitor will Figure-1 be maximum value. Use this value to choose the input capacitor with suitable current rating. Figure-1 shows a schematic of a Buck structure. The waveforms show as Figure-2. Output Capacitor Selection The output voltage ripple is a significant parameter to IL estimate the performance of a convertor. There are IOUT two discrete components that affect the output IIN 0A voltage ripple bigger or smaller. It is recommended to use the criterion has mentioned above to choose a suitable inductor. Then based on this known inductor I(CIN) IIN 0A current ripple condition, the value and properties of output capacitor will affect the output voltage ripple better or worse. The output voltage ripple consists of two portions, one is the product of ESR and inductor current ripple, the other portion is a function of the 0A inductor current ripple and the output capacitance. I(COUT) Figure-3 shows the waveforms to explain the part I(Q1) decided by the output capacitance. IOUT ∆IL 0A 0A I(COUT) D*TS 0.5TS PWM (1-D)*TS ∆VOUT1 0A V OUT Figure-2 Figure-3 Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 11 www.anpec.com.tw APW7134 Application Description (Cont.) Output Capacitor Selection Output Voltage Setting Evaluate the ∆VOUT1 by the ideal of energy equalization. APW7134 has the adjustable version for output volt According to the definition of Q, age setting by the users. A suggestion of maximum Q= 11 1 ∆IL ⋅ TS = C OUT ⋅ ∆VOUT 1 22 2 value of R2 is 200KΩ to keep the minimum current (6) that provides enough noise rejection ability through where TS is the inverse of switching frequency and the the resistor divider. The output voltage programmed ∆IL is the inductor current ripple. Move the COUT to the by the equation: R VOUT = 0 .6 ⋅ 1 + 1 R 2 left side to estimate the value of ∆VOUT1 as equation (7). ∆ VOUT 1 ∆ IL ⋅ TS = 8 ⋅ C OUT (11) (7) VOUT As mentioned above, one part of output voltage ripple APW7134 is the product of the inductor current ripple and ESR of output capacitor. The equation (8) explains the out- R1 FB put voltage ripple estimation. ∆VOUT R2 TS = ∆IL ⋅ ESL + ⋅ 8 C OUT (8) Thermal Considerations Layout Considerations APW7134 is a high efficiency switching converter, it The high current paths (GND1/GND2, IN1/IN2 and means less power loss transferred into heat. Due to SW1/SW2) should be placed very close to the device the on resistance difference between internal power with short, direct and wide traces. Input capacitors PMOSFET and NMOSFET, the power dissipation in should be placed as close as possible to the respec- the high converting ratio is greater than low converting tive IN and GND pins. The external feedback resistors ratio. The worst case is in the dropout operation, the shall be placed next to the FB pins. Keep the switch- mainly conduction loss dissipate on the internal power ing nodes SW1/SW2 short and away from the feed- PMOSFET. The power dissipation nearly defined as: back network. [ ] PD = (IOUT ) RDS_ ONP ⋅ D + RDS_ ONN ⋅ (1− D) 2 (9) APW7134 has internal over temperature protection. W hen the junction temperature reaches 150 centigrade, APW7134 will turn off both internal power PMOSFET and NMOSFET. The estimation of the junction temperature, TJ, defined as: TJ = PD ⋅ θ JA (10) where the θJA is the thermal resistance of the package utilized by APW7134. Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 12 www.anpec.com.tw APW7134 Package Information DFN-10 D b E A A1 D2 L E2 A3 e Dim A A1 A3 b D D2 E E2 e L Millimeters Min. Max. 0.80 1.00 0.00 0.05 0.20 REF 0.18 0.30 3.00 BSC 2.20 2.50 3.00 BSC 1.50 1.80 0.50 BSC 0.35 0.45 Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 13 Inches Min. Max. 0.031 0.039 0.000 0.002 0.008 REF 0.007 0.012 0.118 BSC 0.087 0.098 0.118 BSC 0.059 0.071 0.016 BSC 0.014 0.018 www.anpec.com.tw APW7134 Carrier Tape & Reel Dimensions t D P Po E P1 Bo F W Ao D1 Ko T2 J C A B T1 Application A 178 ± 1 DFN-10 F B C J 54.4 ± 0.4 13.0 + 0.2 2.3 ± 0.1 D D1 5.5 ± 0.05 1.5 + 0.1 1.5 + 0.1 Po T1 T2 W 12.3 ± 1 1.4 ± 0.5 12 ± 0.3 P1 Ao Bo 4.0 ± 0.1 2.0 ± 0.05 3.3 ± 0.1 3.3 ± 0.1 P E 8.0 ± 0.1 1.75 ± 0.1 Ko T 1.1 ± 0.1 0.3 ± 0.05 (mm) Cover Tape Dimensions Application DFN-10 Carrier Width 12 Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 Cover Tape Width 9.2 14 Devices Per Reel 3000 www.anpec.com.tw APW7134 Physical Specifications Terminal Material Lead Solderability Solder-Plated Copper (Solder Material : 90/10 or 63/37 SnPb), 100%Sn Meets EIA Specification RSI86-91, ANSI/J-STD-002 Category 3. Reflow Condition (IR/Convection or VPR Reflow) tp TP Critical Zone T L to T P Temperature Ramp-up TL tL Tsmax Tsmin Ramp-down ts Preheat 25 t 25 °C to Peak Tim e Classificatin Reflow Profiles Profile Feature Average ramp-up rate (TL to TP) Preheat - Temperature Min (Tsmin) - Temperature Max (Tsmax) - Time (min to max) (ts) Time maintained above: - Temperature (TL) - Time (tL) Peak/Classificatioon Temperature (Tp) Time within 5°C of actual Peak Temperature (tp) Ramp-down Rate Sn-Pb Eutectic Assembly Pb-Free Assembly 3°C/second max. 3°C/second max. 100°C 150°C 60-120 seconds 150°C 200°C 60-180 seconds 183°C 60-150 seconds 217°C 60-150 seconds See table 1 See table 2 10-30 seconds 20-40 seconds 6°C/second max. 6°C/second max. 6 minutes max. 8 minutes max. Time 25°C to Peak Temperature Notes: All temperatures refer to topside of the package .Measured on the body surface. Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 15 www.anpec.com.tw APW7134 Classificatin Reflow Profiles(Cont.) Table 1. SnPb Entectic Process – Package Peak Reflow Temperatures 3 3 Package Thickness Volum e m m Volume mm <350 ≥350 <2.5 m m 240 +0/-5°C 225 +0/-5°C ≥2.5 m m 225 +0/-5°C 225 +0/-5°C Table 2. Pb-free Process – Package Classification Reflow Temperatures 3 3 3 Package Thickness Volume mm Volume mm Volume mm <350 350-2000 >2000 <1.6 m m 260 +0°C* 260 +0°C* 260 +0°C* 1.6 m m – 2.5 m m 260 +0°C* 250 +0°C* 245 +0°C* ≥2.5 m m 250 +0°C* 245 +0°C* 245 +0°C* *Tolerance: The device manufacturer/supplier shall assure process compatibility up to and including the stated classification temperature (this means Peak reflow temperature +0°C. For example 260°C+0°C) at the rated MSL level. Reliability test program Test item SOLDERABILITY HOLT PCT TST ESD Latch-Up Method MIL-STD-883D-2003 MIL-STD-883D-1005.7 JESD-22-B,A102 MIL-STD-883D-1011.9 MIL-STD-883D-3015.7 JESD 78 Description 245°C, 5 SEC 1000 Hrs Bias @125°C 168 Hrs, 100%RH, 121°C -65°C~150°C, 200 Cycles VHBM > 2KV, VMM > 200V 10ms, 1 tr > 100mA Customer Service Anpec Electronics Corp. Head Office : No.6, Dusing 1st Road, SBIP, Hsin-Chu, Taiwan, R.O.C. Tel : 886-3-5642000 Fax : 886-3-5642050 Taipei Branch : 7F, No. 137, Lane 235, Pac Chiao Rd., Hsin Tien City, Taipei Hsien, Taiwan, R. O. C. Tel : 886-2-89191368 Fax : 886-2-89191369 Copyright ANPEC Electronics Corp. Rev. A.1 - Aug., 2006 16 www.anpec.com.tw