Overview

The CD4553 (CD4553B) is a 3-digit BCD counter IC manufactured by Texas Instruments and ON Semiconductor. It contains three cascaded BCD counters, an internal quad 4-bit latch, and a multiplexing circuit that outputs the 4-bit BCD data of each digit sequentially over a single 4-bit bus (Q0–Q3) alongside three active-LOW digit select outputs (DS1‾,DS2‾,DS3‾\overline{DS1}, \overline{DS2}, \overline{DS3}).

Operating from 3.0V to 18.0V DC, the CD4553 is designed to drive 3-digit 7-segment LED displays when paired with a single BCD-to-7-segment decoder IC (such as the CD4511), dramatically reducing pin count in digital event counters, frequency meters, and digital panel meters.

Quick reference

Supply Voltage (VDD - VSS)3.0 V to 18.0 V DC
Digits3 Synchronous BCD Counter Digits (0 to 999 count capacity)
Output Bus4-Bit Time-Multiplexed BCD Bus (Q0, Q1, Q2, Q3)
Digit Selection3 Active-LOW Digit Select Lines (DS1‾,DS2‾,DS3‾\overline{DS1}, \overline{DS2}, \overline{DS3})
Clock FrequencyUp to 6.0 MHz6.0\text{ MHz} at VDD=15VVDD = 15\text{V} (2.5 MHz2.5\text{ MHz} at 5V5\text{V})
Latch MemoryIntegrated 4-bit quad storage latches for display freezing
Package16-pin DIP / SOIC-16

Pinout (DIP-16 Package)

text
             ┌───┴───┐
        C1A 1│ 1   16│ VDD (+3V to +18V)
        C1B 2│       │15 CLK (Clock Input)
        DIS 3│ CD4553│14 /DS3 (Digit 3 Select)
        C2A 4│       │13 /DS2 (Digit 2 Select)
        C2B 5│       │12 /DS1 (Digit 1 Select)
         LE 6│       │11 Q2 (BCD Bit 2)
         Q3 7│       │10 Q1 (BCD Bit 1)
   VSS(GND) 8│       │9  Q0 (BCD Bit 0)
             └───────┘
PinNameTypeDescription
1, 2C1A, C1BInputScan Oscillator Timing Capacitor Pins (Connect external capacitor)
3DISInputDisable / Reset Control Input (High = Reset counter to 000)
4, 5C2A, C2BInputSecondary Timing Capacitor Pins
6LEInputLatch Enable Input (High = Freeze display value; Low = Pass-through)
7Q3OutputMultiplexed BCD Output Bit 3 (MSB)
8VSSPowerDigital Ground (0 V)
9Q0OutputMultiplexed BCD Output Bit 0 (LSB)
10Q1OutputMultiplexed BCD Output Bit 1
11Q2OutputMultiplexed BCD Output Bit 2
12\DS1OutputActive-LOW Digit 1 (LSD) Select Output
13\DS2OutputActive-LOW Digit 2 Select Output
14\DS3OutputActive-LOW Digit 3 (MSD) Select Output
15CLKInputMaster Clock Input (Positive edge triggered)
16VDDPowerPositive Power Supply (+3.0V to +18.0V DC)

Multi-Digit Display Interface with CD4511 Decoder

text
   CD4553 Counter                  CD4511 Decoder               3-Digit 7-Seg LED Display
  ┌──────────────┐                ┌──────────────┐             ┌─────────────────────────┐
  │ Q0,Q1,Q2,Q3  ├───────────────►│ A, B, C, D   │             │   Common-Cathode LEDs   │
  │ (BCD Bus)    │                │ a,b,c,d,e,f,g├────────────►│ a,b,c,d,e,f,g (Parallel)│
  │              │                └──────────────┘             └─────────────────────────┘
  │ /DS1,/DS2,/DS3├───[PNP Transistors (BC557)]───────────────► Digits 1, 2, 3 Cathodes
  └──────────────┘

Common mistakes

  • Leaving Latch Enable (LE, Pin 6) floating: LE must be tied directly to GND for normal real-time counting. Leaving LE floating freezes the displayed value indefinitely.
  • Forgetting PNP driver transistors on Digit Select lines: DS1‾,DS2‾,DS3‾\overline{DS1}, \overline{DS2}, \overline{DS3} are active-LOW logic signals designed to drive base leads of PNP transistors (like 2SA1015 or BC327) that switch high-side digit power in multiplexed displays.

Notes

  • CD4553 vs 74HC393: CD4553 provides 3 full BCD digits with built-in multiplexer logic; 74HC393 is a raw dual 4-bit binary counter requiring external multiplexing.

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