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Part: 74F845SC
Category:
Description: 8-Bit Transparent Latch
Company: Fairchild Semiconductor
Datasheet: Download 74F845SC datasheet File size : 180 kB
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74F845 8-Bit Transparent Latch
April 1988 Revised October 2000
74F845 8-Bit Transparent Latch
General Description
The 74F845 bus interface latch is designed to eliminate the extra packages required to buffer existing latches and provide extra data width for wider address/data paths or buses carrying parity. The 74F845 is functionally- and pin-compatible with AMD's Am29845.
Features
s 3-STATE outputs s Direct replacement for AMD's Am29845
Ordering Code:
Order Number 74F845SC 74F845SPC Package Number M24B N24C Package Description 24-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide 24-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter "X" to the ordering code.
Logic Symbols
Connection Diagram
IEEE/IEC
© 2000 Fairchild Semiconductor Corporation
DS009601
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74F845
Unit Loading/Fan Out
Pin Names D0D7 O0O7 OE1OE3 LE CLR PRE Description Data Inputs Data Outputs Output Enables Latch Enable Clear Preset U.L . HIGH/LOW 1.0/1.0 150/40 1.0/1.0 1.0/1.0 1.0/1.0 1.0/1.0 Input IIH/IIL Output IOH/IOL 20 µA/-0.6 mA
-3.0 µA/24 mA
20 µA/-0.6 mA 20 µA/-0.6 mA 20 µA/-0.6 mA 20 µA/-0.6 mA
Functional Description
The 74F845 consists of eight D-type latches with 3-STATE outputs. The flip-flops appear transparent to the data when Latch Enable (LE) is HIGH. This allows asynchronous operation as the output transition follows the data in transition. On the LE HIGH-to-LOW transition, the data that meets the setup times is latched. Data appears on the bus when the output Enable (OE) is LOW. When OE is HIGH, the bus output is in the high impedance state.
Function Table
Inputs CLR PRE OE H H H H H H H H L L L H H H H H H H H L H L H L H H H H L L L L L L H H LE X H H L H H L X X X L L D X L H X L H X X X X X X Internal Output Function Q X L H NC L H NC H L H L H O Z Z Z Z L H NC H L H Z Z High Z High Z High Z Latched Transparent Transparent Latched Preset Clear Preset Latched Latched
H = HIGH Voltage Level L = LOW Voltage Level X = Immaterial
Z = High Impedance NC = No Change
Logic Diagram
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
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74F845
Absolute Maximum Ratings(Note 1)
Storage Temperature Ambient Temperature under Bias Junction Temperature under Bias VCC Pin Potential to Ground Pin Input Voltage (Note 2) Input Current (Note 2) Voltage Applied to Output in HIGH State (with VCC = 0V) Standard Output 3-STATE Output Current Applied to Output in LOW State (Max) twice the rated IOL (mA)
-65°C to +150°C -55°C to +125°C -55°C to +150°C -0.5V to +7.0V -0.5V to +7.0V -30 mA to +5.0 mA
Recommended Operating Conditions
Free Air Ambient Temperature Supply Voltage 0°C to +70°C
+4.5V to +5.5V
-0.5V to VCC -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. Note 2: Either voltage limit or current limit is sufficient to protect inputs.
DC Electrical Characteristics
Symbol VIH VIL VCD VOH Parameter Input HIGH Voltage Input LOW Voltage Input Clamp Diode Voltage Output HIGH Voltage 10% VCC 10% VCC 5% VCC 5% VCC VOL IIH IBVI ICEX VID IOD IIL IOZH IOZL IOS IZZ ICCZ Output LOW Voltage Input HIGH Current Input HIGH Current Breakdown Test Output HIGH Leakage Current Input Leakage Test Output Leakage Circuit Current Input LOW Current Output Leakage Current Output Leakage Current Output Short-Circuit Current Bus Drainage Test Power Supply Current 63 -60 4.75 3.75 -0.6 50 -50 -150 500 85 10% VCC 2.5 2.4 2.7 2.7 0.5 5.0 7.0 50 V µA µA µA V µA mA µA µA mA µA mA Min Max Max Max 0 .0 0 .0 Max Max Max Max 0.0V Max V Min M in 2.0 0.8 -1.2 Typ Max Units V V V Min V CC Conditions Recognized as a HIGH Signal Recognized as a LOW Signal IIN = -18 mA IOH = -1 mA IOH = -3 mA IOH = -1 mA IOH = -3 mA IOL = 24 mA VIN = 2.7V VIN = 7.0V VOUT = VCC IID = 1.9 µA All Other Pins Grounded VIOD = 150 mV All Other Pins Grounded VIN = 0.5V VOUT = 2.7V VOUT = 0.5V VOUT = 0V VOUT = 5.25V VO = HIGH Z
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74F845
AC Electrical Characteristics
TA = +25°C Symbol Parameter Min tPLH tPHL tPLH tPHL tPLH tPHL tPZH tPZL tPHZ tPLZ Propagation Delay Dn to On Propagation Delay LE to On Propagation Delay PRE to On Propagation Delay CLR to On Output Enable Time OE to On Output Disable Time OE to On 2.5 1.5 5.0 2.0 3.0 3.0 2.5 2.5 1.0 1.0 VCC = +5.0V CL = 50 pF Typ 4.8 3.6 8.1 4.4 5.9 6.5 5.8 7.6 3.1 2.8 Max 8.0 6.5 12.0 7.5 10.0 10.0 9.5 12.0 7.5 6.5 TA= 0°C to +70°C VCC = +5.0V CL = 50 pF Min 2.0 1 .5 4.5 2 .0 2.5 2.5 2.0 2.0 1.0 1 .0 Max 9.0 7.0 13.5 8.0 11.0 11.0 10.5 13.0 8.5 7.5 ns ns ns ns ns ns Units
AC Operating Requirements
TA = +25°C Symbol Parameter VCC = +5.0V Min tS(H) tS(L) tH(H) tH(L) tW(H) tW(L) tW(L) tREC tREC Setup Time, HIGH or LOW Dn to LE Hold Time, HIGH or LOW Dn to LE LE Pulse Width, HIGH PRE Pulse Width, LOW CLR Pulse Width, LOW PRE Recovery Time CLR Recovery Time 2.0 2.0 2.5 3.0 4.0 5.0 5.0 10.0 12.0 M ax TA= 0°C to +70°C VCC = +5.0V Min 2.5 2 .5 3.0 3 .5 4 .0 5.0 5.0 10.0 13.0 Max ns ns ns ns ns ns ns Units
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74F845
Physical Dimensions inches (millimeters) unless otherwise noted
24-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide Package Number M24B
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