74HC4511 — High-Speed CMOS BCD-to-7-Segment Latch/Decoder/Driver

Overview

The 74HC4511 (CD74HC4511E) is a high-speed CMOS BCD-to-7-segment latch/decoder/driver IC manufactured by Texas Instruments, Nexperia, and ON Semiconductor. It accepts a 4-bit Binary Coded Decimal (BCD) input ( $A, B, C, D$ ) and decodes it into active-HIGH signals ( $a, b, c, d, e, f, g$ ) to drive common-cathode 7-segment LED displays directly.

Operating over 2.0V to 6.0V DC, the 74HC4511 features internal 4-bit data storage latches, a Lamp Test input ( $\overline{LT}$ — turns on all 7 segments for display testing), and a Blanking input ( $\overline{BL}$ — turns off all segments for power saving or PWM dimming).

Quick reference


Supply Voltage (`VCC`)	2.0 V to 6.0 V DC
Logic Family	High-Speed CMOS (74HC) / TTL Compatible (74HCT)
Input Format	4-bit BCD ( $A, B, C, D$ — LSB to MSB)
Output Drive	7 Active-HIGH outputs ( $a \dots g$ , up to $25\text{ mA}$ source current per segment)
Display Type	Common-Cathode 7-Segment LED Displays
Control Pin Features	Latch Enable ( $\overline{LE}$ ), Lamp Test ( $\overline{LT}$ ), Blanking ( $\overline{BL}$ )
Package	16-pin DIP / SOIC-16 / TSSOP-16

Pinout (DIP-16 Package)

text

             ┌───┴───┐
          B 1│ 1   16│ VCC (+2V to +6V)
          C 2│       │15 f
        /LT 3│ 74HC  │14 g
        /BL 4│ 4511  │13 a
        /LE 5│       │12 b
          D 6│       │11 c
          A 7│       │10 d
        GND 8│       │9  e
             └───────┘

Pin	Name	Type	Description
1	`B`	Input	BCD Bit 1 Input ( $2^1 = 2$ )
2	`C`	Input	BCD Bit 2 Input ( $2^2 = 4$ )
3	`\LT`	Input	Lamp Test Input (Active LOW: Low = Turn ON all segments $a \dots g$ )
4	`\BL`	Input	Blanking Input (Active LOW: Low = Turn OFF all segments $a \dots g$ )
5	`\LE`	Input	Latch Enable Input (Active LOW: Low = Pass-through; High = Latch BCD data)
6	`D`	Input	BCD Bit 3 Input ( $2^3 = 8$ , MSB)
7	`A`	Input	BCD Bit 0 Input ( $2^0 = 1$ , LSB)
8	`GND`	Power	Ground reference (0 V)
9–15	`e, d, c, b, a, g, f`	Output	7-Segment Active-HIGH LED Driver Outputs
16	`VCC`	Power	Positive Power Supply (+2.0V to +6.0V DC)

Truth Table & Decoded Output Numbers

BCD Input ( $D,C,B,A$ )	Decoded Digit	Active Segments ( $a \dots g$ )
$0000_2$ ( $0$ )	`0`	$a, b, c, d, e, f$ (HIGH)
$0001_2$ ( $1$ )	`1`	$b, c$ (HIGH)
$0010_2$ ( $2$ )	`2`	$a, b, d, e, g$ (HIGH)
$0011_2$ ( $3$ )	`3`	$a, b, c, d, g$ (HIGH)
$0100_2$ ( $4$ )	`4`	$b, c, f, g$ (HIGH)
$0101_2$ ( $5$ )	`5`	$a, c, d, f, g$ (HIGH)
$0110_2$ ( $6$ )	`6`	$a, c, d, e, f, g$ (HIGH)
$0111_2$ ( $7$ )	`7`	$a, b, c$ (HIGH)
$1000_2$ ( $8$ )	`8`	$a, b, c, d, e, f, g$ (HIGH)
$1001_2$ ( $9$ )	`9`	$a, b, c, d, f, g$ (HIGH)
$> 1001_2$ ( $10\dots15$ )	Blank	All segments OFF ( $a \dots g$ LOW)

Common mistakes

Leaving $\overline{LT}$ , $\overline{BL}$ , or $\overline{LE}$ floating: Control pins $\overline{LT}$ (Pin 3) and $\overline{BL}$ (Pin 4) must be tied to $V_{CC}$ for normal display operation. Pin $\overline{LE}$ (Pin 5) must be tied to GND. Leaving them floating causes dark or blank displays.
Connecting to Common-Anode displays: The 74HC4511 has active-HIGH outputs, meant to drive Common-Cathode 7-segment displays. Connect current-limiting resistors ( $220\ \Omega \dots 470\ \Omega$ ) between outputs $a \dots g$ and the display pins.

Notes

74HC4511 vs CD4511: 74HC4511 operates on 2V to 6V logic levels at high speed; CD4511 operates on 3V to 18V CMOS power rails.