Si4700DY New Product Vishay Siliconix Power Selector Switch MOSFETs Configured To Give Spdt Switch With One Control Input 2.5- to 8-V Ground Referenced Control Input 30-m Main Switch On-Resistance 70-m Alternate Switch On-Resistance SOIC-8 Package 3000-V ESD Protection On Control Input Zero Power Consumption In Alternate Power Mode ACPI Power Switching In Desktop Computers 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. 4 Q1 5, 6, 7 VS2 VD RG 8 VG 3 Q2 CO 1 Load VS1 Q3 ON/OFF 2 GND Document Number: 71110 S-00025—Rev. A, 24-Jan-00 www.vishay.com FaxBack 408-970-5600 2-1 Si4700DY New Product Vishay Siliconix ABSOLUTE MAXIMUM RATINGS (TA = 25_C UNLESS OTHERWISE NOTED) Parameter Symbol Q1 Drain-Source Voltage Q2 Logic Control Input 10 sec Q1 Q2 Q1 Pulsed Drain Currentb Q2 Q1 Continuous Intrinsic Diode Conductiona Q2 Maximum Power Dissipationa ID –12 PD Operating Junction and Storage Temperature Range ESD Voltagec V 8 7.6 5.3 5.0 3.5 20 IDM IS Unit 12 VDS VIN Continuous Drain Currenta Steady State A 20 2.1 1.15 2.1 1.15 2.35 1.25 W Tj, Tstg –55 to 150 _C ESD 3 KV Notes a. Surface mounted on 1” x1” FR4 board. b. Pulse test: pulse width 300 mS, duty cycle 2%. c. Equivalent to MIL-STD-883D Human Body Model (100 pF, 1500 W) THERMAL RESISTANCE RATINGS Parameter Symbol t 10 sec Maximum Junction-to-Ambienta Steady State Maximum Junction-to-Foot (Drain)b Steady State RthJA RthJF Typical Maximum 43 53 82 100 25 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 b l VDS = –12 V, VGS = 0 V Off S State Leakage L k Current C Gate-Body Leakage Gate-Threshold Voltage O R i On-Resistance IDSS Min Specific Test Conditions S ifi T C di i Typa Max Q1 1 Q2 –1 VDS = –8 V, VGS = 0 V Q3 1 VDS = –12 V, VGS = 0 V, TJ = 55_C Q2 –5 IGSS VDS = 0 V, VGS = 4.5 V Q3 VGS(th) VDS = VGS, ID = 250 mA Q3 VS = 4.5 V, ID = 1 A, VON/OFF = 2.5 V Q1 25 30 VS = 2.5 V, ID = 1 A, VON/OFF = 2.5 V Q1 32 40 VS = 4.5 V, ID = 1 A, VON/OFF = 2.5 V Q2 58 70 VS = 2.5 V, ID = 1 A, VON/OFF = 2.5 V Q2 90 110 rDS(on) Unit mA A 1 0.6 V mW W Notes a. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. www.vishay.com S FaxBack 408-970-5600 2-2 Document Number: 71110 S-00025—Rev. A, 24-Jan-00 Si4700DY New Product Vishay Siliconix PIN CONFIGURATION SO-8 VIN 1 8 VGATE GND 2 7 DRAIN Q2 SOURCE 3 6 DRAIN Q1 SOURCE 4 5 DRAIN TRUTH TABLE VIN Q1 Q2 L ON OFF H OFF ON Top View Order Number: Si4700DY PIN DESCRIPTION Pin Number Symbol Description 1 VON/OFF 2 GND 3 Q2 SOURCE Input for alternate power 4 Q1 SOURCE Input for main power 5, 6, 7 DRAIN Output 8 VGATE Gate drive voltage via pull-up resistor Logic Input Signal Ground (reference for logic input and power ground) TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) N-CHANNEL VDROP vs. IL VDROP vs. IL 0.35 0.25 VON/OFF = 2.5 V VS2 = –4.5 V IL = –1 A VON/OFF = 2.5 V VS2 = –2.5 V IL = –1 A 0.20 VDROP (V) VDROP (V) 0.28 0.21 125_C 0.14 0.15 125_C 25_C 0.10 25_C 0.07 0.05 0 0 0 2 4 6 IL (A) Document Number: 71110 S-00025—Rev. A, 24-Jan-00 8 10 0 1 2 3 4 5 IL (A) www.vishay.com S FaxBack 408-970-5600 2-3 Si4700DY New Product Vishay Siliconix TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) VDROP vs. S2 0.10 N-CHANNEL VDROP Variance vs. Junction Temperature 0.015 VON/OFF = 2.5 V VS2 = –4.5 V IL = –1 A 0.012 0.009 VDROP Variance (V) VDROP (V) 0.08 0.06 VON/OFF = 2.5 V IL = –1 A 0.04 0.006 0.003 0.000 0.02 –0.003 0 0 2 4 6 8 –0.006 –50 10 –25 0 rDS(on) Variation with Input Voltage 50 75 0.08 0.06 VON/OFF = 2.5 V IL = –1 A 0.04 0.02 0 150 VON/OFF = 2.5 V VS2 = –4.5 V IL = –1 A 1.4 1.2 1.0 2 4 6 8 0.6 –50 10 –25 0 VS2 (V) 25 50 75 VDROP vs. IL 1.0 125 150 P-CHANNEL VDROP vs. IL 0.70 VON/OFF = 2.5 V VS1 = 4.5 V IL = 1 A VON/OFF = 2.5 V VS1 = 2.5 V IL = 1 A 0.56 VDROP (V) 0.8 100 TJ – Junction Temperature (_C) TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) VDROP (V) 125 0.8 0 0.6 125_C 0.4 25_C 0.2 0.42 125_C 25_C 0.28 0.14 0 0 0 2 4 6 IL (A) www.vishay.com S FaxBack 408-970-5600 2-4 100 Normalized rDS(on) vs. Junction Temperature 1.6 r DS(on) – On-Resistance ( ) Normalized r DS(on) – On-Resistance ( ) 0.10 25 TJ – Junction Temperature (_C) VS2 (V) 8 10 0 1 2 3 4 5 IL (A) Document Number: 71110 S-00025—Rev. A, 24-Jan-00 Si4700DY New Product Vishay Siliconix TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) P-CHANNEL VDROP Variance vs. Junction Temperature VDROP vs. S1 0.30 0.04 VDROP Variance (V) VDROP (V) VON/OFF = 2.5 V VS1 = 4.5 V IL = 1 A 0.03 0.24 0.18 VON/OFF = 2.5 V IL = 1 A 0.12 0.06 0.02 0.01 0.00 –0.01 0 0 2 4 6 8 –0.02 –50 10 –25 rDS(on) Variation with Input Voltage 50 75 100 125 150 Normalized rDS(on) vs. Junction Temperature 0.30 r DS(on) – On-Resistance ( W ) Normalized 1.6 0.24 0.18 VON/OFF = 2.5 V IL = 1 A 0.12 0.06 VON/OFF = 2.5 V VS2 = 4.5 V IL = 1 A 1.4 1.2 1.0 0.8 0 0 2 4 6 8 0.6 –50 10 VS2 (V) –25 0 25 50 75 100 125 150 TJ – Junction Temperature (_C) td(on) Variation with RG/VS1 trise Variation with RG/VS1 8 1.5 VS! = 2.5 V VON/OFF = 3 V VG = 12 V CO = 10 mF IL = 1 A 6 VS! = 2.5 V Time ( m S) 1.2 Time ( m S) 25 TJ – Junction Temperature (_C) VS2 (V) r DS(on) – On-Resistance ( W ) 0 0.9 VS! = 3.3 V 0.6 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 0.3 0 0 0 20 40 60 RG (kW) Document Number: 71110 S-00025—Rev. A, 24-Jan-00 80 100 0 20 40 60 80 100 RG (kW) www.vishay.com S FaxBack 408-970-5600 2-5 Si4700DY New Product Vishay Siliconix TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) P-CHANNEL td(off) Variation with RG/VS1 tf Variation with RG/VS1 100 200 VON/OFF = 3 V VG = 12 V CO = 10 mF IL = 1 A VON/OFF = 3 V VG = 12 V CO = 10 mF IL = 1 A 160 Time ( m S) Time ( m S) 80 60 VS! = 2.5 V VS! = 3.3 V 40 VS! = 2.5 V 120 VS! = 3.3 V 80 VS! = 5 V 20 40 VS! = 5 V 0 0 0 20 40 60 80 100 0 20 40 RG (kW) 60 80 100 RG (kW) TYPICAL CHARACTERISTICS (25_C UNLESS NOTED) ALL CHANNELS Normalized Thermal Transient Impedance, Junction-to-Ambient 2 Normalized Effective Transient Thermal Impedance 1 Duty Cycle = 0.5 0.2 Notes: 0.1 0.1 PDM 0.05 t1 t2 1. Duty Cycle, D = t1 t2 2. Per Unit Base = RthJA = 82_C/W 0.02 3. TJM – TA = PDMZthJA(t) Single Pulse 0.01 10–4 4. Surface Mounted 10–3 10–2 10–1 1 10 100 600 Square Wave Pulse Duration (sec) Normalized Thermal Transient Impedance, Junction-to-Foot Normalized Effective Transient Thermal Impedance 2 1 Duty Cycle = 0.5 0.2 0.1 0.1 0.05 0.02 Single Pulse 0.01 10–4 10–3 www.vishay.com S FaxBack 408-970-5600 2-6 10–2 10–1 Square Wave Pulse Duration (sec) 1 10 Document Number: 71110 S-00025—Rev. A, 24-Jan-00 Si4700DY New Product Vishay Siliconix 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 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). 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 k, 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 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. 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 Si4700DY has a maximum rDS(on) of 30 m for the n-channel MOSFET used during normal operation and 70 m 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 power supply shutdown control in ATX power supply Main 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 FaxBack 408-970-5600 2-7 Si4700DY New Product Vishay Siliconix +12 V Si4700DY Main Supply Q1 Seconday supply Load Q2 Control Q3 FIGURE 2. Si4700DY used for ACPI Power Switching www.vishay.com FaxBack 408-970-5600 2-8 Document Number: 71110 S-00025—Rev. A, 24-Jan-00