Revised August 1999 74F2645 Octal Bus Transceiver with 25Ω Series Resistors in the Outputs General Description Features This device is an octal bus transceiver designed for asynchronous two-way data flow between the A and B busses and is functionally equivalent to the 74F645. The 25Ω series resistors in the outputs reduce ringing and eliminate the need for external resistors. Both busses are capable of sinking 12 mA, sourcing 15 mA, have 3-STATE outputs, and a common output enable pin. The direction of data flow is determined by the transmit/receive (T/R) input. The 74F2645 is a low power version of the 74F245 with 25Ω series resistors in the outputs. ■ 25Ω series resistors in the outputs eliminates the need for external resistors ■ Designed for asynchronous two-way data flow between busses ■ Outputs sink 12 mA and source 15 mA ■ Transmit/receive (T/R) input controls the direction of data flow ■ 74F2645 is a low power version of the 74F245 with 25Ω series resistors in the outputs Ordering Code: Order Number Package Number 74F2645SC M20B Package Description 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code. Logic Symbol Connection Diagram FAST is a registered trademark of Fairchild Semiconductor Corporation. © 1999 Fairchild Semiconductor Corporation DS010629 www.fairchildsemi.com 74F2645 Octal Bus Transceiver November 1989 74F2645 Unit Loading/Fan Out Pin Names Description U.L. Input IIH/IIL HIGH/LOW Output IOH/IOL OE Output Enable Input (Active LOW) 1.0/1.0 20 µA/−0.6 mA T/R Transmit/Receive Input 1.0/1.0 20 µA/−0.6 mA 3.5/0.667 70 µA/−0.4 mA A0–A7 Side A Inputs or 750/20 −15 mA/12 mA 3.5/0.667 70 µA/−0.4 mA 750/20 −15 mA/12 mA 3-STATE Outputs B0–B7 Side B Inputs or 3-STATE Outputs Function Table Functional Description The output enable (OE) is active LOW. If the device is disabled (OE HIGH), the outputs are in the high impedance state. The transmit/receive input (T/R) controls whether data is transmitted from the A bus to the B bus or from the B bus to the A bus. When T/R is LOW, B data is sent to the A bus. If T/R is HIGH, A data is sent to the B bus. Inputs Outputs OE L L Bus B data to Bus A L H Bus A data to Bus B H X Z H = HIGH Voltage Level L = LOW Voltage Level X = Don’t Care Z = High Impedance State Logic Diagram www.fairchildsemi.com 2 T/R Recommended Operating Conditions Storage Temperature −65°C to +150°C Ambient Temperature under Bias −55°C to +125°C Free Air Ambient Temperature Junction Temperature under Bias −55°C to +150°C Supply Voltage 0°C to +70°C +4.5V to +5.5V −0.5V to +7.0V VCC Pin Potential to Ground Pin Input Voltage (Note 2) −0.5V to +7.0V Input Current (Note 2) −30 mA to +5.0 mA Voltage Applied to Output in HIGH State (with VCC = 0V) Standard Output −0.5V to VCC 3-STATE Output −0.5V to +5.5V Note 1: Absolute maximum ratings are values beyond which the device may be damaged or have its useful life impaired. Functional operation under these conditions is not implied. Current Applied to Output Note 2: Either voltage limit or current limit is sufficient to protect inputs. twice the rated IOL (mA) in LOW State (Max) ESD Last Passing Voltage (Min) 4000V DC Electrical Characteristics Symbol Parameter Min Typ Max VCC VIL Input LOW Voltage 0.8 V VCD Input Clamp Diode Voltage −1.2 V Min IIN = −18 mA (Non I/O Pins) VOH Output HIGH V Min IOH = −15 mA (An, Bn) V Min 5.0 µA Max VIN = 2.7V (Non I/O Pins) 7.0 µA Max VIN = 7.0V (Non I/O Pins) 0.5 mA Max VIN = 5.5V (An, Bn) 50 µA Max VOUT = VCC V 0.0 3.75 µA 0.0 −0.6 mA Max VIN = 0.5V (Non I/O Pins) 70 µA Max VOUT = 2.7V (An, Bn) −650 µA Max VOUT = 0.5V (An, Bn) −225 mA Max VOUT = 0V VOL IIH 10% VCC V Conditions Input HIGH Voltage Voltage 2.0 Units VIH 2.0 Output LOW 10% VCC 0.50 Voltage 10% VCC 0.75 Input HIGH Current IBVI Input HIGH Current Breakdown Test IBVIT Input HIGH Current Breakdown (I/O) ICEX Output HIGH Leakage Current VID Input Leakage Test IOD 4.75 Output Leakage Circuit Current Recognized as a HIGH Signal Recognized as a LOW Signal IOL = 1 mA (An, Bn) IOL = 12 mA (A n, Bn) IID = 1.9 µA All Other Pins Grounded VIOD = 150 mV All Other Pins Grounded IIL Input LOW Current IIH + IOZH Output Leakage Current IIL + IOZL Output Leakage Current IOS Output Short-Circuit Current IZZ Bus Drainage Test 500 µA 0.0V VOUT = 5.25 ICCL Power Supply Current (74F2645) 82 mA Max VO = LOW, VIN = 0.2V ICCZ Power Supply Current (74F2645) 95 mA Max VO = HIGH Z −100 3 www.fairchildsemi.com 74F2645 Absolute Maximum Ratings(Note 1) 74F2645 AC Electrical Characteristics Symbol Parameter Min TA = +25°C TA = 0°C to +70°C VCC = +5.0V VCC = +5.0V CL = 50 pF CL = 50 pF Max Min Max tPLH Propagation Delay 1.5 Typ 6.0 1.5 7.0 tPHL A Input to B Output 2.5 7.5 2.5 8.0 tPLH Propagation Delay 1.5 6.0 1.5 7.0 tPHL B Input to A Output 2.5 7.5 2.5 8.0 tPZH Enable Time 2.5 8.0 2.0 9.0 tPZL OE Input to A Output 2.5 8.5 2.0 8.5 tPHZ Disable Time 1.5 7.0 1.0 8.0 tPLZ OE Input to A Output 1.0 5.5 1.0 5.5 tPZH Enable Time 2.5 7.5 2.0 9.5 tPZL OE Input to B Output 2.5 8.5 2.5 9.0 tPHZ Disable Time 1.5 6.5 1.0 7.5 tPLZ OE Input to B Output 1.0 6.5 1.0 6.5 Basic FAST Circuit Showing Series Resistor Placement www.fairchildsemi.com 4 Units ns ns ns ns 74F2645 Octal Bus Transceiver Physical Dimensions inches (millimeters) unless otherwise noted 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide Package Number M20B Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right at any time without notice to change said circuitry and specifications. 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