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74LVC245APW

Octal bus transceiver, 1.2-3.6V, 5V tolerant, 24mA, 3-state, TSSOP-20

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Manufacturer Part：

74LVC245APW

Package：

TSSOP-20 SOT360-1 (6.5 x 4.4 x 1.1mm, 0.65mm pitch)

Brand：

Product Categories：

Integrated Circuits ICs, Interface ICs

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Description

Product Overview

The 74LVC245APW is an octal bus transceiver from Nexperia with 3-state outputs, 5V tolerant I/O, direction control, and 24mA drive in a TSSOP-20 package.

Key Specifications

Number of Bits	8
Supply Voltage (VCC)	1.2V to 3.6V
Input Voltage Tolerance	Up to 5.5V (overvoltage tolerant)
Output Drive	±24mA
Propagation Delay	17ns max (at 3.3V)
Max Frequency	175MHz
Output Type	3-state (high-impedance when disabled)
Direction Control	DIR pin (A→B or B→A)
Output Enable	OE pin (active low)
Ioff Support	Yes (partial power-down safe)
Schmitt Trigger	Yes (on all inputs)
Operating Temperature	-40°C to +125°C
Package	TSSOP-20 (6.5 x 4.4mm)

Features

8-bit bidirectional bus transceiver with 3-state outputs
5V tolerant inputs/outputs for mixed 3.3V/5V designs
Wide supply voltage: 1.2V to 3.6V
±24mA balanced output drive
DIR pin controls data direction (A→B or B→A)
OE pin disables both buses (high-impedance)
Schmitt-trigger inputs tolerate slow edge rates
Ioff circuitry prevents backflow during power-down
Direct interface with TTL and CMOS logic levels

Applications

Mixed 3.3V/5V voltage level translation
Bus buffering and isolation
Microprocessor I/O port expansion
Memory bus interface
Backplane driving

Product Introduction:74LVC245APW Product Introduction

The 74LVC245APW from Nexperia is an 8-bit bidirectional bus transceiver with 3-state outputs designed for asynchronous communication between data buses. The DIR (direction) pin selects whether data flows from the A bus to the B bus or vice versa. The OE (output enable) pin, when high, places both buses in high-impedance state for bus isolation. The 5V tolerant inputs and outputs enable direct interfacing between 3.3V and 5V logic systems without external level shifters. Schmitt-trigger inputs on all pins tolerate slow input edge rates, making the device suitable for接收 signals from RC-filtered or open-drain sources. The Ioff circuitry ensures that when VCC is 0V, the I/O pins present high impedance, preventing damaging backflow current in partial power-down scenarios. The ±24mA output drive capability can directly drive heavy capacitive loads or backplane traces. The APW suffix denotes the TSSOP-20 package.

Working Principle:74LVC245APW Working Principle

The 74LVC245APW contains eight identical bidirectional transceiver cells, each connecting one A-bus pin to one B-bus pin through a pair of tristate buffers. When DIR is high, the A-to-B buffers are enabled and the B-to-A buffers are disabled, allowing data to flow from A to B. When DIR is low, the B-to-A buffers are enabled and data flows from B to A. The OE pin controls the overall enable: when OE is low, the selected direction is active; when OE is high, all buffers are disabled and both A and B buses are in high-impedance state. The 5V tolerance works because the input protection diodes clamp to VCC only when the input voltage exceeds VCC, but the Ioff circuitry disconnects these diodes when VCC is 0V, allowing the pin to float without drawing current. When the device is powered (VCC = 3.3V), the 5V-tolerant inputs can accept voltages up to 5.5V without forward-biasing the input diodes, because the protection structure is designed to tolerate this overvoltage. The Schmitt-trigger input stage provides hysteresis (typically 200mV at 3.3V), converting slowly rising or falling input signals into clean logic transitions.

Pin Description:74LVC245APW Pin Definition and Functions

Pin	Name	Type	Description
1	DIR	Input	Direction control (high=A→B, low=B→A)
2	A1	I/O	A-bus data pin 1
3	A2	I/O	A-bus data pin 2
4	A3	I/O	A-bus data pin 3
5	A4	I/O	A-bus data pin 4
6	A5	I/O	A-bus data pin 5
7	A6	I/O	A-bus data pin 6
8	A7	I/O	A-bus data pin 7
9	A8	I/O	A-bus data pin 8
10	GND	Power	Ground
11	B8	I/O	B-bus data pin 8
12	B7	I/O	B-bus data pin 7
13	B6	I/O	B-bus data pin 6
14	B5	I/O	B-bus data pin 5
15	B4	I/O	B-bus data pin 4
16	B3	I/O	B-bus data pin 3
17	B2	I/O	B-bus data pin 2
18	B1	I/O	B-bus data pin 1
19	OE	Input	Output enable (active low)
20	VCC	Power	Supply (1.2V to 3.6V)

Application Scenarios:In which products and applications is74LVC245APW used

Level Translation: 5V tolerant I/O translates between 3.3V MCU and 5V peripheral buses without external level shifters
Bus Isolation: OE pin disconnects two buses during hot-plug or debug, preventing contention between drivers
Buffering: ±24mA drive boosts 3.3V MCU output current for long PCB traces or backplane loads
Memory Interface: DIR and OE provide read/write direction control for shared memory bus between CPU and DMA
Power-Down Safe: Ioff prevents backflow when one side of the bus is powered while the other is off (hot-swap)

Alternative Models:What chips are recommended as replacements for 74LVC245APW

Model	Manufacturer	Key Difference	Package	Supply
74LS245N	TI/Nexperia	Original TTL version with 5V-only supply, typical propagation delay 10-15ns	DIP-20	5V TTL
74LS245D	TI/Nexperia	Surface-mount SOIC version of LS with identical logic function	SOIC-20	5V TTL
74HC245D	TI/Nexperia	CMOS version with wide 2-6V supply range, lower power consumption and higher noise immunity	SOIC-20	2-6V CMOS
74HC245N	TI/Nexperia	Through-hole DIP version of HC family for prototyping and repair	DIP-20	2-6V CMOS
74HCT245D	TI/Nexperia	CMOS with TTL-compatible input levels, ideal for mixing with LS devices at 5V	SOIC-20	4.5-5.5V TTL-in
74HCT245N	TI/Nexperia	Through-hole DIP version of HCT family for prototyping and repair	DIP-20	4.5-5.5V TTL-in
74LVC245D	TI/Nexperia	Low-voltage CMOS for 1.65-3.6V modern logic with 24mA output drive and bus-hold inputs	SOIC-20	1.65-3.6V CMOS
74LVC245N	TI/Nexperia	Through-hole DIP version of LVC family for prototyping and repair	DIP-20	1.65-3.6V CMOS
74AUP245D	TI/Nexperia	Ultra-low power CMOS with 0.8-3.6V supply for battery-powered and mobile applications	SOIC-20	0.8-3.6V CMOS
74AUP245N	TI/Nexperia	Through-hole DIP version of AUP family for prototyping and repair	DIP-20	0.8-3.6V CMOS

The 74245 is a Octal Bus Transceiver with 3-State Output. Family variants span from the original LS TTL (5V only) to modern LVC/AUP (down to 0.8V). HC and HCT versions offer 2-6V CMOS operation with HCT providing TTL-compatible input thresholds for mixed 5V systems. CD4000-series equivalents offer the widest 3-18V supply range at the cost of lower switching speed. DIP packages (N suffix) are through-hole; SOIC (D suffix) and TSSOP are surface-mount.