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IC Pinouts / 74HC245

74HC245 Pinout

74HC245 Octal Bus Transceiver · 8-bit bidirectional bus transceiver, three-state outputs; DIR controls direction, /OE enables; common for data-bus buffering / level isolation.

DIP-20 Logic 20 pins No backend · 100% client-side
DIR 1
A1 2
A2 3
A3 4
A4 5
A5 6
A6 7
A7 8
A8 9
GND 10
74HC245 DIP-20
20 VCC
19 OE(/OE)
18 B1
17 B2
16 B3
15 B4
14 B5
13 B6
12 B7
11 B8
PowerGNDInputOutputI/OControl
PinNameTypeFunction
1 DIR Control Direction: high = A→B, low = B→A
2 A1 I/O A-side data 1
3 A2 I/O A-side data 2
4 A3 I/O A-side data 3
5 A4 I/O A-side data 4
6 A5 I/O A-side data 5
7 A6 I/O A-side data 6
8 A7 I/O A-side data 7
9 A8 I/O A-side data 8
10 GND GND Ground
11 B8 I/O B-side data 8
12 B7 I/O B-side data 7
13 B6 I/O B-side data 6
14 B5 I/O B-side data 5
15 B4 I/O B-side data 4
16 B3 I/O B-side data 3
17 B2 I/O B-side data 2
18 B1 I/O B-side data 1
19 OE · /OE Control Output enable (active-low; high gives three-state high-impedance)
20 VCC Power Supply + (2–6V)
How to · reading it

How to read the 74HC245 pinout

  1. 01

    Find pin 1

    One end of the chip has a half-circle notch or a dot; with the notch facing up, the top-left pin is pin 1.

  2. 02

    Count counter-clockwise

    Count counter-clockwise from pin 1: go down the left side first, then up the right side from the bottom.

  3. 03

    Check the table below

    Look up each pin's function by number in the table below; power/ground are color-coded, and alternate-function signals are in parentheses.

FAQ

Frequently asked questions

How do DIR and /OE work together?

It only operates when /OE=low; DIR=high gives A→B, DIR=low gives B→A. When /OE=high both A and B are high-impedance, disconnected from the bus.

Which B pin does A1 correspond to?

A1↔B1, A2↔B2… A8↔B8 (note A is in ascending order on 2–9, B in descending order on 11–18).

Can it do 5V↔3.3V level conversion?

The 74HC245 cannot (single supply). For dual-supply level conversion use the 74LVC245 or a dedicated level translator.

Data source

Pinout data comes from NXP/TI 74HC245 datasheet (standard DIP-20 numbering). Refer to the actual device datasheet as authoritative for the pinout.

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