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| IDTQS3388 HIGH-SPEED CMOS BUS EXCHANGE SWITCH WITH ACTIVE TERMINATION INDUSTRIAL TEMPERATURE RANGE QUICKSWITCH(R) PRODUCTS HIGH-SPEED CMOS BUS EXCHANGE SWITCH WITH ACTIVE TERMINATION (BUS HOLD) FEATURES: * Enhanced N channel FET with no inherent diode to Vcc * 5 bidirectional switches connect inputs to outputs * Active termination drives bus pins to rails when switches are off * Zero propagation delay, zero added ground bounce * Undershoot clamp diodes on all switch and control inputs * Bus exchange allows nibble swap * TTL-compatible input and output levels * Bus-hold eliminates floating bus lines and reduces static power consumption * Available in QSOP package IDTQS3388 DESCRIPTION: The QS3388 provides ten high-speed CMOS TTL-compatible bus switches with active terminators on the bus switch I/O pins. The low ON resistance (5) of the 3388 allows inputs to be connected to outputs without adding propagation delay and without generating additional ground bounce noise. When the switches are turned off, a low drive active terminator circuit drives the disconnected pins to VCC or ground, away from the TTL threshold. This prevents undriven buses from floating. The Bus Enable (BE) signal turns the switches on. The Bus Exchange (BX) signal provides nibble swap of the AB and CD pairs of signals. This exchange configuration allows byte swapping of buses in systems. It can also be used as a five-wide 2-to-1 multiplexer and to create low delay barrel shifters, etc. The QS3388 is characterized for operation at -40C to +85C. APPLICATIONS: * Resource sharing * Crossbar switching * Last value latch (graphics and DSP) FUNCTIONAL BLOCK DIAGRAM A0 T T C0 R B0 T T D0 T = A4 T T C4 B4 T T D4 BX BE The IDT logo is a registered trademark of Integrated Device Technology, Inc. INDUSTRIAL TEMPERATURE RANGE 1 c 2000 Integrated Device Technology, Inc. APRIL 2000 DSC-5765/1 IDTQS3388 HIGH-SPEED CMOS BUS EXCHANGE SWITCH WITH ACTIVE TERMINATION INDUSTRIAL TEMPERATURE RANGE PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS(1) Symbol VTERM(2) Description Supply Voltage to Ground DC Switch Voltage VS DC Input Voltage VIN AC Input Voltage (pulse width 20ns) DC Output Current Maximum Power Dissipation (TA = 85C) Storage Temperature Max -0.5 to +7 -0.5 to +7 -0.5 to +7 -3 120 0.5 -65 to +150 Unit V V V V mA W C VTERM(3) VTERM(3) VAC IOUT PMAX TSTG BE C0 A0 B0 D0 C1 A1 B1 D1 C2 A2 GND 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 QSOP TOP VIEW 2 4 2 3 2 2 2 1 2 0 1 9 1 8 1 7 1 6 1 5 1 4 1 3 VCC D4 B4 A4 C4 D3 B3 A3 C3 D2 B2 BX NOTES: 1. Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. 2. VCC terminals. 3. All terminals except VCC . CAPACITANCE (TA = +25C, f = 1MHz, VIN = 0V, VOUT = 0V) Pins Control Inputs Quickswitch Channels (Switch OFF) Typ. 3 5 Max. (1) 5 7 Unit pF pF NOTE: 1. This parameter is guaranteed but not production tested. PIN DESCRIPTION Pin Names A0 - A4, B0 - B4 C0 - C4, D0 - D4 BE BX I/O I/O I/O I I Description A and B Buses C and D Buses Bus Switch Enable Bus Exchange FUNCTION TABLE(1) BE H L L BX X L H A0 - A4 Hi-Z C0 - C4 D0 - D4 B0 - B4 Hi-Z D0 - D4 C0 - C4 Function Disconnect Connect Exchange NOTE: 1. H = HIGH Voltage Level L = LOW Voltage Level X = Don't Care Z = High-Impedance 2 IDTQS3388 HIGH-SPEED CMOS BUS EXCHANGE SWITCH WITH ACTIVE TERMINATION INDUSTRIAL TEMPERATURE RANGE DC ELECTRICAL CHARACTERISTICS OVER OPERATING RANGE Following Conditions Apply Unless Otherwise Specified: Industrial: TA = -40C to +85C, VCC = 5V 5% Symbol VIH VIL IIN RON IBH IBHH IBHL Parameter Input HIGH Voltage Input LOW Voltage Input Leakage Current (Control Inputs) Switch ON Resistance Input Current (2) Switch Pins Bus Hold Sustaining Source Current - HIGH(3) Bus Hold Sustaining Sink Current - LOW(4) Test Conditions Guaranteed Logic HIGH for Control Pins Guaranteed Logic LOW for Control Pins 0V VIN Vcc Vcc = Min., VIN = 0V, ION = 30mA Vcc = Min., VIN = 2.4V, ION = 15mA Vcc = Max., VIN = 0V or Vcc Vcc = Max., 0.8V < VIN < 2V Vcc = Min., VIN = 2V Vcc = Min., VIN = 0.8V Min. 2 -- -- -- -- -- -- Typ.(1) Max. -- -- .01 6 12 -- -- -- -- -- 0.8 1 8 17 20 500 -- -- A A Unit V V A - 60 + 60 NOTES: 1. Typical values are at VCC = 5.0V, TA = 25C. 2. Input current specified under two conditions: a) Input voltage at GND or Vcc. This indicates the input current under steady-state condition. b) Input voltage between 0.8V and 2V (TTL input threshold range). This indicates the maximum input current during transient condition. The driver connected to the input must overcome this current requirement in order to switch the logic state of the bus-hold circuit. 3. IBHH represents the latching capability of the bus-hold circuit in logic HIGH state. 4. IBHL represents the latching capability of the bus-hold circuit in logic LOW state. TYPICAL ON RESISTANCE vs VIN AT VCC = 5V 16 RON (ohms) 14 12 10 8 6 4 2 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 VIN (Volts) 3 IDTQS3388 HIGH-SPEED CMOS BUS EXCHANGE SWITCH WITH ACTIVE TERMINATION INDUSTRIAL TEMPERATURE RANGE POWER SUPPLY CHARACTERISTICS Symbol ICCQ ICC ICCD Parameter Quiescent Power Supply Current Power Supply Current per Input HIGH(2) Dynamic Power Supply Current per MHz (3) Test Conditions(1) VCC = Max., VIN = GND or VCC, f = 0 VCC = Max., VIN = 3.4V, f = 0 VCC = Max., A - D Pins Open, Control Inputs Toggling @ 50% Duty Cycle Max. 1.5 2.5 0.25 Unit mA mA mA/MHz NOTES: 1. For conditions shown as Min. or Max., use the appropriate values specified under DC Electrical Characteristics. 2. Per TTL-driven input (VIN = 3.4V, control inputs only). A - D pins do not contribute to Icc. 3. This current applies to the control inputs only and represents the current required to switch internal capacitance at the specified frequency. The A-D inputs generate no significant AC or DC currents as they transition. This parameter is guaranteed but not production tested. SWITCHING CHARACTERISTICS OVER OPERATING RANGE TA = -40C to +85C, VCC = 5V 5% CLOAD = 50pF, RLOAD = 500 unless otherwise noted. Symbol tPLH tPHL tPZL tPZH tPLZ tPHZ tBX Parameter Data Propagation Delay(2) AxBx to CxDx, CxDx to AxBx Switch Turn-On Delay BE to Ax, Bx, Cx, Dx Switch Turn-Off Delay(2) BE to Ax, Bx, Cx, Dx Switch Multiplex Delay BX to Ax, Bx, Cx, Dx 1.5 6.5 ns 1.5 1.5 6.5 5.5 ns ns Min. (1) Typ. Max. 0.25(3) Unit ns NOTES: 1. Minimums are guaranteed but not production tested. 2. This parameter is guaranteed but not production tested. 3. The bus switch contributes no propagation delay other than the RC delay of the ON resistance of the switch and the load capacitance. The time constant for the switch alone is of the order of 0.25ns at CL = 50pF. Since this time constant is much smaller than the rise and fall times of typical driving signals, it adds very little propagation delay to the system. Propagation delay of the bus switch, when used in a system, is determined by the driving circuit on the driving side of the switch and its interaction with the load on the driven side. 4 IDTQS3388 HIGH-SPEED CMOS BUS EXCHANGE SWITCH WITH ACTIVE TERMINATION INDUSTRIAL TEMPERATURE RANGE ACTIVE TERMINATOR OR `BUS-HOLD' CIRCUIT The Active Terminator circuit, also known as the Bus-hold circuit, is configured as a "weak latch" with positive feedback. When connected to a TTL or CMOS input port, the Bus-hold circuit holds the last logic state at the input when the input is "disconnected" from the driver. When the output of a device connected to such an input attempts a logic level transition, it will over-drive the Bus-hold circuit. The primary benefit of this circuit is that it prevents CMOS inputs from floating, a situation which should be avoided to prevent spurious switching of inputs and unnecessary power dissipation. Bus-hold is a better solution than the traditional approach of using resistive termination to VCC or GND to prevent bus floating, because the Bus-hold circuit does not consume any static power. V-I CHARACTERISTICS OF BUS-HOLD CIRCUIT IBH + 500 Sinking Current (+) IBHL IBH IBHH Sourcing Current (-) +60 +20 - 20 - 60 +60 IBHL VT Voltage + 20 IBH - 20 IBH - 60 IBHH Vcc VIL VIH IBH - 500 0.8V 2V VT Threshold Voltage 1.5V VIL .8 VIH 2V The figure above shows the input V-I characteristics of a Bus-hold implementation. The input characteristics resemble a resistor. As the input voltage is increased from 0 volts, the `sink' current increases linearly. When the TTL threshold of the circuit is reached (typically 1.5 volts), the latch changes the logic state due to positive feedback and the direction of current is reversed. As the voltage is further increased towards VCC, the input `source' current begins to decrease, reaching the lowest level at VIN = VCC. 5 IDTQS3388 HIGH-SPEED CMOS BUS EXCHANGE SWITCH WITH ACTIVE TERMINATION INDUSTRIAL TEMPERATURE RANGE ORDERING INFORMATION IDTQS XXXXX Device Type XX Package X Process Blank Industrial (-40C to +85C) Q Quarter Size Outline Package 3388 High Speed CMOS Bus Exchange Switch with Active Termination (Bus Hold) CORPORATE HEADQUARTERS 2975 Stender Way Santa Clara, CA 95054 for SALES: 800-345-7015 or 408-727-6116 fax: 408-492-8674 www.idt.com for Tech Support: logichelp@idt.com (408) 654-6459 6 |
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