The SN74LVC245APWR is a product manufactured by Texas Instruments (TI). It is an octal bus transceiver , used in digital circuits to allow for bi-directional data transfer between different devices while maintaining high-speed data integrity.
Packaging:
The SN74LVC245APWR comes in a TSSOP-20 package, which refers to Thin Shrink Small Outline Package with 20 pins.
Pin Function Specifications and Circuit Principle:
Here is a detailed breakdown of the pin functions for the SN74LVC245APWR in a TSSOP-20 package. Each pin has a specific function in the transceiver circuit. Below is the 20-pin function table:
Pin Number Pin Name Pin Function Description 1 A1 Data input/output for the first 8-bit bus; transmits data to the bus when enabled by control signals. 2 A2 Data input/output for the second 8-bit bus; used in bidirectional data transfer when enabled. 3 A3 Data input/output for the third 8-bit bus; transmits data to the bus when enabled by control signals. 4 A4 Data input/output for the fourth 8-bit bus; used in bidirectional data transfer when enabled. 5 A5 Data input/output for the fifth 8-bit bus; transmits data to the bus when enabled by control signals. 6 A6 Data input/output for the sixth 8-bit bus; used in bidirectional data transfer when enabled. 7 A7 Data input/output for the seventh 8-bit bus; transmits data to the bus when enabled by control signals. 8 A8 Data input/output for the eighth 8-bit bus; used in bidirectional data transfer when enabled. 9 GND Ground connection for the IC. 10 DIR Direction control input pin: determines if the data flow is from A1-A8 or from B1-B8 (direction pin). 11 OE Output enable pin: controls whether the output is enabled (active-low). 12 B1 Data input/output for the first 8-bit bus; receives data from the bus when the direction is set accordingly. 13 B2 Data input/output for the second 8-bit bus; used in bidirectional data transfer. 14 B3 Data input/output for the third 8-bit bus; transmits data to the bus when enabled by control signals. 15 B4 Data input/output for the fourth 8-bit bus; used in bidirectional data transfer when enabled. 16 B5 Data input/output for the fifth 8-bit bus; transmits data to the bus when enabled by control signals. 17 B6 Data input/output for the sixth 8-bit bus; used in bidirectional data transfer when enabled. 18 B7 Data input/output for the seventh 8-bit bus; transmits data to the bus when enabled by control signals. 19 B8 Data input/output for the eighth 8-bit bus; used in bidirectional data transfer when enabled. 20 VCC Power supply connection for the IC.Circuit Principle:
The SN74LVC245APWR operates as an octal bus transceiver with control signals that enable or disable the flow of data in either direction (from A to B or from B to A). The OE (Output Enable) pin must be low for the outputs to be active. The DIR (Direction) pin defines the direction of data flow: when DIR is high, data flows from A to B, and when DIR is low, data flows from B to A.
20 Common FAQs (Question-Answer Format):
Q1: What is the main function of the SN74LVC245APWR? A1: The SN74LVC245APWR is a bus transceiver designed to facilitate bidirectional data transfer on an 8-bit bus.
Q2: How many pins does the SN74LVC245APWR have? A2: The SN74LVC245APWR has 20 pins in total.
Q3: What is the purpose of the OE pin? A3: The OE pin is the Output Enable pin. When OE is low, the outputs are enabled, allowing data transfer to/from the bus.
Q4: What happens when the DIR pin is set high? A4: When the DIR pin is high, the data direction is set from A to B (A1-A8 to B1-B8).
Q5: What does the DIR pin do? A5: The DIR pin controls the direction of data flow, determining whether data moves from A to B or from B to A.
Q6: How does the SN74LVC245APWR help with data integrity? A6: It ensures high-speed, reliable data transfer with low voltage swings, maintaining signal integrity across buses.
Q7: What is the voltage range for the SN74LVC245APWR? A7: The SN74LVC245APWR operates within a voltage range of 2.0V to 5.5V.
Q8: Can the SN74LVC245APWR be used for both input and output? A8: Yes, it supports bidirectional data transfer, meaning it can be used both as an input and output depending on the DIR and OE settings.
Q9: How many channels are there for data transfer? A9: The device supports 8-bit channels, with two 8-bit buses for each direction, meaning 16 channels in total.
Q10: What is the TSSOP-20 package? A10: The TSSOP-20 package is a Thin Shrink Small Outline Package with 20 pins, providing a compact form factor for the IC.
Q11: Is there any special condition for using the OE pin? A11: Yes, the OE pin should be low to enable the outputs. If it’s high, the outputs are disabled.
Q12: Can I use the SN74LVC245APWR in high-speed applications? A12: Yes, the SN74LVC245APWR is designed to work at high speeds, making it suitable for high-frequency digital circuits.
Q13: How do I connect the VCC and GND pins? A13: VCC should be connected to the positive power supply (e.g., 5V), and GND should be connected to the system ground.
Q14: What is the typical propagation delay for the SN74LVC245APWR? A14: The typical propagation delay is around 3ns, depending on operating conditions.
Q15: Can this IC be used in automotive applications? A15: Yes, with proper voltage regulation, the SN74LVC245APWR can be used in automotive systems, as it meets the required voltage levels and robustness.
Q16: How does the DIR pin control the direction? A16: The DIR pin sets the data flow direction. When it is high, data moves from A to B, and when low, data moves from B to A.
Q17: Are there any current limits for each pin? A17: Each pin can handle up to 25mA of current, but it’s advisable to stay within the recommended operating limits for best performance.
Q18: How does the device behave when OE is high? A18: When OE is high, all output drivers are disabled, and the transceivers are in a high-impedance state, effectively "tri-stating" the output.
Q19: What are the key applications for the SN74LVC245APWR? A19: It is typically used in data buses, memory interfacing, and signal processing circuits where bi-directional data transfer is required.
Q20: How should I handle the SN74LVC245APWR to prevent damage? A20: Handle it carefully to avoid ESD (Electrostatic Discharge), and ensure correct pin connections for VCC and GND to avoid malfunction or damage.
This detailed breakdown of the SN74LVC245APWR covers the key aspects of its functionality, pinout, and usage, providing a thorough understanding of this component for your design.
