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| SI4700DY New Product Vishay Siliconix Power Selector Switch FEATURES D MOSFETs Configured To Give Spdt Switch With One Control Input D 2.5- to 8-V Ground Referenced Control Input D 30-mW Main Switch On-Resistance D 70-mW Alternate Switch On-Resistance D SOIC-8 Package D 3000-V ESD Protection On Control Input D Zero Power Consumption In Alternate Power Mode APPLICATIONS D ACPI Power Switching In Desktop Computers DESCRIPTION The SI4700DY consists of two MOSFETs configured for use as a single-pole, double-throw (SPDT) switch. A single ground referenced input, controls which switch is on. The SI4700DY is intended for use in applications where two power sources are available and the circuit must select one of the two depending on the conditions. An example of such a circuit is ACPI implementation in computers where part of a circuit must switch to an "always-on" power supply when the computer is in suspend mode, but runs off the main power supply for normal operation. FUNCTIONAL BLOCK DIAGRAM AND PIN CONFIGURATION 4 VS2 RG VG 3 VS1 8 Q1 5, 6, 7 VD Q2 CO 1 ON/OFF Q3 2 GND Document Number: 71110 S-00025--Rev. A, 24-Jan-00 Load www.vishay.com S FaxBack 408-970-5600 2-1 SI4700DY Vishay Siliconix New Product ABSOLUTE MAXIMUM RATINGS (TA = 25_C UNLESS OTHERWISE NOTED) Parameter Drain-Source Voltage Logic Control Input Continuous Drain Currenta Pulsed Drain Currentb Q1 Q2 Q1 Q2 Q1 Q2 Q1 Q2 Symbol VDS VIN ID IDM 10 sec 12 -12 8 7.6 5.0 20 20 2.1 2.1 2.35 Steady State Unit V 5.3 3.5 A 1.15 1.15 1.25 -55 to 150 3 W _C KV Continuous Intrinsic Diode Conductiona Maximum Power Dissipationa Operating Junction and Storage Temperature Range ESD Voltagec IS PD Tj, Tstg ESD Notes a. Surface mounted on 1" x1" FR4 board. b. Pulse test: pulse width v300 mS, duty cycle v2%. c. Equivalent to MIL-STD-883D Human Body Model (100 pF, 1500 W) THERMAL RESISTANCE RATINGS Parameter Maximum Junction-to-Ambienta Maximum Junction-to-Foot (Drain)b t v 10 sec Steady State Steady State Symbol RthJA RthJF Typical 43 82 25 Maximum 53 100 30 Unit _C/W C/W Notes a. Surface Mounted on 1" x 1" FR4 Board. b. Junction-to-foot thermal impedance represents the effective thermal impedance of all heat carrying leads in parallel and is intended for use in conjunction with the thermal impedance of the PC board pads to ambient (RthJA = RthJF + RthPCB-A). It can also be used to estimate chip temperature if power dissipation and the lead temperature of a heat carrying (drain) lead is known. SPECIFICATIONS Limits Parameter P Symbol S bl Specific T S ifi Test Conditions C di i Q1 Q2 Q3 Q2 Q3 Q3 Q1 Q1 Q2 Q2 0.6 25 32 58 90 30 40 70 110 mW W Min Typa Max Unit VDS = -12 V, VGS = 0 V Off S State L k Leakage Current C IDSS VDS = -8 V, VGS = 0 V VDS = -12 V, VGS = 0 V, TJ = 55_C Gate-Body Leakage Gate-Threshold Voltage IGSS VGS(th) VDS = 0 V, VGS = "4.5 V VDS = VGS, ID = 250 mA VS = 4.5 V, ID = 1 A, VON/OFF = 2.5 V On-Resistance ORi rDS(on) VS = 2.5 V, ID = 1 A, VON/OFF = 2.5 V VS = 4.5 V, ID = 1 A, VON/OFF = 2.5 V VS = 2.5 V, ID = 1 A, VON/OFF = 2.5 V Notes a. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. www.vishay.com S FaxBack 408-970-5600 1 -1 1 -5 "1 V mA A 2-2 Document Number: 71110 S-00025--Rev. A, 24-Jan-00 SI4700DY New Product PIN CONFIGURATION Vishay Siliconix SO-8 VIN GND Q2 SOURCE Q1 SOURCE 1 2 3 4 8 7 6 5 VGATE DRAIN DRAIN DRAIN TRUTH TABLE VIN L H Q1 ON OFF Q2 OFF ON Top View Order Number: SI4700DY PIN DESCRIPTION Pin Number 1 2 3 4 5, 6, 7 8 Symbol VON/OFF GND Q2 SOURCE Q1 SOURCE DRAIN VGATE Logic Input Signal Description Ground (reference for logic input and power ground) Input for alternate power Input for main power Output Gate drive voltage via pull-up resistor TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) N-CHANNEL VDROP vs. IL 0.35 VON/OFF = 2.5 V VS2 = -4.5 V IL = -1 A VDROP (V) 0.25 VDROP vs. IL 0.28 0.20 VON/OFF = 2.5 V VS2 = -2.5 V IL = -1 A VDROP (V) 0.21 125_C 0.14 25_C 0.07 0.15 125_C 0.10 25_C 0.05 0 0 2 4 IL (A) 6 8 10 0 0 1 2 IL (A) 3 4 5 Document Number: 71110 S-00025--Rev. A, 24-Jan-00 www.vishay.com S FaxBack 408-970-5600 2-3 SI4700DY Vishay Siliconix New Product N-CHANNEL 0.015 0.012 0.08 VDROP Variance (V) 0.009 0.006 0.003 0.000 -0.003 0 0 2 4 VS2 (V) 0.10 6 8 10 -0.006 -50 TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) 0.10 VDROP vs. S2 VDROP Variance vs. Junction Temperature VON/OFF = 2.5 V VS2 = -4.5 V IL = -1 A VDROP (V) 0.06 VON/OFF = 2.5 V IL = -1 A 0.04 0.02 -25 0 25 50 75 100 125 150 TJ - Junction Temperature (_C) 1.6 rDS(on) Variation with Input Voltage Normalized rDS(on) vs. Junction Temperature VON/OFF = 2.5 V VS2 = -4.5 V IL = -1 A r DS(on) - On-Resistance ( W ) 0.08 r DS(on) - On-Resistance ( W ) Normalized 8 10 1.4 0.06 VON/OFF = 2.5 V IL = -1 A 0.04 1.2 1.0 0.02 0.8 0 0 2 4 VS2 (V) 6 0.6 -50 -25 0 25 50 75 100 125 150 TJ - Junction Temperature (_C) TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) VDROP vs. IL VON/OFF = 2.5 V VS1 = 4.5 V IL = 1 A VDROP (V) P-CHANNEL VDROP vs. IL VON/OFF = 2.5 V VS1 = 2.5 V IL = 1 A 1.0 0.70 0.8 0.56 VDROP (V) 0.6 125_C 0.4 25_C 0.42 125_C 25_C 0.28 0.2 0.14 0 0 2 4 IL (A) www.vishay.com S FaxBack 408-970-5600 6 8 10 0 0 1 2 IL (A) Document Number: 71110 S-00025--Rev. A, 24-Jan-00 3 4 5 2-4 SI4700DY New Product TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) VDROP vs. S1 0.30 0.04 VON/OFF = 2.5 V VS1 = 4.5 V IL = 1 A Vishay Siliconix P-CHANNEL VDROP Variance vs. Junction Temperature 0.24 VDROP Variance (V) 8 10 0.03 0.02 VDROP (V) 0.18 VON/OFF = 2.5 V IL = 1 A 0.12 0.01 0.00 0.06 -0.01 0 0 2 4 VS2 (V) 6 -0.02 -50 -25 0 25 50 75 100 125 150 TJ - Junction Temperature (_C) rDS(on) Variation with Input Voltage 0.30 1.6 Normalized rDS(on) vs. Junction Temperature r DS(on) - On-Resistance ( W ) 0.24 r DS(on) - On-Resistance ( W ) Normalized 1.4 VON/OFF = 2.5 V VS2 = 4.5 V IL = 1 A 0.18 VON/OFF = 2.5 V IL = 1 A 0.12 1.2 1.0 0.06 0.8 0 0 2 4 VS2 (V) 6 8 10 0.6 -50 -25 0 25 50 75 100 125 150 TJ - Junction Temperature (_C) td(on) Variation with RG/VS1 1.5 VON/OFF = 3 V VG = 12 V CO = 10 mF IL = 1 A 8 trise Variation with RG/VS1 VS! = 2.5 V 6 1.2 VS! = 2.5 V Time ( m S) VS! = 3.3 V 4 VS! = 5 V VS! = 5 V 2 VON/OFF = 3 V VG = 12 V CO = 10 mF IL = 1 A 0 20 40 RG (kW) 60 80 100 VS! = 3.3 V Time ( m S) 0.9 0.6 0.3 0 0 20 40 RG (kW) 60 80 100 0 Document Number: 71110 S-00025--Rev. A, 24-Jan-00 www.vishay.com S FaxBack 408-970-5600 2-5 SI4700DY Vishay Siliconix New Product P-CHANNEL tf Variation with RG/VS1 200 VON/OFF = 3 V VG = 12 V CO = 10 mF IL = 1 A Time ( m S) VON/OFF = 3 V VG = 12 V CO = 10 mF IL = 1 A TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) td(off) Variation with RG/VS1 100 80 160 VS! = 2.5 V Time ( m S) 60 VS! = 2.5 V 40 VS! = 3.3 V 120 VS! = 3.3 V 80 VS! = 5 V 20 VS! = 5 V 0 0 20 40 RG (kW) 60 80 100 40 0 0 20 40 RG (kW) 60 80 100 TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) Normalized Thermal Transient Impedance, Junction-to-Ambient 2 1 Normalized Effective Transient Thermal Impedance Duty Cycle = 0.5 ALL CHANNELS 0.2 Notes: 0.1 0.1 0.05 0.02 PDM t1 t2 1. Duty Cycle, D = t1 t2 2. Per Unit Base = RthJA = 82_C/W 3. TJM - TA = PDMZthJA(t) Single Pulse 0.01 10-4 10-3 10-2 10-1 1 4. Surface Mounted 10 100 600 Square Wave Pulse Duration (sec) Normalized Thermal Transient Impedance, Junction-to-Foot 2 1 Duty Cycle = 0.5 Normalized Effective Transient Thermal Impedance 0.2 0.1 0.1 0.05 0.02 Single Pulse 0.01 10-4 10-3 10-2 10-1 Square Wave Pulse Duration (sec) 1 10 www.vishay.com S FaxBack 408-970-5600 2-6 Document Number: 71110 S-00025--Rev. A, 24-Jan-00 SI4700DY New Product Vishay Siliconix TYPICAL APPLICATIONS The Si4700 is designed to be used to select one of two power sources for a circuit, such as needed to implement ACPI in desktop computers. In this application, parts of the circuit must run off an always-on power supply when the computer is in suspend mode. When in normal mode, these circuits run off the main power supply. The SI4700DY switch is a break-before-make configuration, therefore sufficient capacitance must be present on the isolated load to ensure hold up during switching. Due to fast switching times this should not be significant and is preferred over a make-before-break that would connect the two power supplies directly for a short period. The SI4700DY contains an n-channel MOSFET and a p-channel MOSFET switch connected together to make a single-pole, double-throw switch. An additional on-board small signal MOSFET provides a ground referenced logic input. When the control input is high, the power MOSFET gates are pulled to ground, and the p-channel MOSFET is on. When the input is low, the gates are pulled above the supply rail, and the n-channel MOSFET is on (pulling the gate of the p-channel above the source potential has no effect). Note that the n-channel MOSFET is oriented to ensure that the internal diode does not conduct while the sub-circuit is isolated. In this direction it also provides a fail-safe path for the circuit's power through the diode. The forward drop of the p-channel MOSFET's diode will block any current back-feeding the secondary supply, assuming the two supplies are very close in voltage. The gate drive for the n-channel device, Q1, uses an external 12-V supply via an external resistor. A typical value for this resistor is around 20 kW, but the value is not critical as long as the current in Q3 is kept below 0.05 A. A higher value of resistance reduces the current while in suspend mode, but also introduces a longer delay when turning on Q1. The SI4700DY has a maximum rDS(on) of 30 mW for the n-channel MOSFET used during normal operation and 70 mW for the p-channel used when the computer is in suspend, making it ideal for loads up to 3 A or higher depending on voltage drop requirements. It can be used on any rail voltage between 2.5 V and 8 V (based on an absolute max of 12 V), with a logic input between 2.5-V and 5-V nominal. Seconday supply (always on) SPDT switch required to isolate circuit and connect to VSTANDBY Main Supply Main power supply shutdown control in ATX power supply ACPI Control Main Circuit Always-On Circuit FIGURE 1. ACPI Power Switching Application Document Number: 71110 S-00025--Rev. A, 24-Jan-00 www.vishay.com S FaxBack 408-970-5600 2-7 SI4700DY Vishay Siliconix New Product +12 V SI4700DY Main Supply Q1 Seconday supply Q2 Control Q3 FIGURE 2. SI4700DY used for ACPI Power Switching www.vishay.com S FaxBack 408-970-5600 Load 2-8 Document Number: 71110 S-00025--Rev. A, 24-Jan-00 |
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