Overview

The CD4503 (commonly CD4503BE in a 16-pin DIP package) is a high-voltage CMOS hex non-inverting 3-state buffer IC belonging to the standard 4000B logic family. It contains six independent buffer gates designed to drive digital buses or high-capacitance loads.

The six buffers are divided into two groups: four buffers controlled by Disable Input A (DIS A), and two buffers controlled by Disable Input B (DIS B). Bringing a disable input HIGH forces its corresponding buffer outputs into a high-impedance (tri-state) OFF condition.

Quick reference

Logic FamilyHigh-Voltage CMOS (4000B Series)
Package16-Pin DIP (Through-Hole) / SOIC-16 / TSSOP-16
Supply Voltage Range (VDDV_{DD})3.0 V3.0\text{ V} to 18.0 V18.0\text{ V} DC
Number of Channels6 Non-Inverting 3-State Buffers (4-bit + 2-bit groups)
Propagation Delay (tpdt_{pd})75 ns75\text{ ns} typical at VDD=10VV_{DD} = 10\text{V}
Output Sink/Source CurrentUp to 10 mA10\text{ mA} at VDD=15VV_{DD} = 15\text{V}
Disable ControlsDIS A (Controls Outputs 1–4), DIS B (Controls Outputs 5–6)

Pinout (16-Pin DIP Package)

text
        ┌──────────────┐
  DIS A ─│ 1         16 │─ VDD
     A1 ─│ 2         15 │─ DIS B
     Y1 ─│ 3         14 │─ Y6
     A2 ─│ 4         13 │─ A6
     Y2 ─│ 5         12 │─ Y5
     A3 ─│ 6         11 │─ A5
     Y3 ─│ 7         10 │─ Y4
    VSS ─│ 8          9 │─ A4
        └──────────────┘
PinNameDescription
1DIS ADisable input for Buffers 1–4 (High = High-Z Output, Low = Enabled)
2, 4, 6, 9A1–A4Data inputs for Buffers 1–4
3, 5, 7, 10Y1–Y43-state data outputs for Buffers 1–4
8VSSGround reference (0 V)
11, 13A5–A6Data inputs for Buffers 5–6
12, 14Y5–Y63-state data outputs for Buffers 5–6
15DIS BDisable input for Buffers 5–6 (High = High-Z Output, Low = Enabled)
16VDDPositive power supply input (+3V to +18V DC)

Truth Table

Data Input (A_n)Disable Input (DIS)Output (Y_n)
Low (0)Low (0)Low (0)
High (1)Low (0)High (1)
X (Don't care)High (1)High-Impedance (Z)

Specifications

ParameterSymbolMinTypMaxUnitConditions
Supply Voltage RangeVDDV_{DD}3.05 / 1218.0VDC operating range
High-Level Output VoltsVOHV_{OH}4.955.0—VVDD=5V,IO=0V_{DD} = 5\text{V}, I_O = 0
Low-Level Output VoltsVOLV_{OL}—0.00.05VVDD=5V,IO=0V_{DD} = 5\text{V}, I_O = 0
Propagation DelaytPLH/tPHLt_{PLH} / t_{PHL}—75150nsVDD=10V,CL=50pFV_{DD} = 10\text{V}, C_L = 50\text{pF}
Output Enable/Disable TimetPZL/tPLZt_{PZL} / t_{PLZ}—60120nsVDD=10V,CL=50pFV_{DD} = 10\text{V}, C_L = 50\text{pF}
Quiescent Supply CurrentIDDI_{DD}—0.021.0μA\mu\text{A}VDD=5V,VIN=0VV_{DD} = 5\text{V}, V_{IN} = 0\text{V} or VDDV_{DD}

Common mistakes

  • Confusing active-HIGH disable with active-LOW enable: The CD4503 uses Disable inputs (DIS A, DIS B). Drive DIS LOW to enable outputs; driving DIS HIGH disables the buffer.
  • Leaving unused inputs floating: Like all CMOS ICs, unused data or disable inputs must be tied to VDDV_{DD} or VSSV_{SS} to prevent shoot-through current spikes and floating input oscillations.

Notes

  • 4000B High-Voltage Capability: Unlike 74HC series buffers limited to 6V max, the CD4503 supports supply voltages up to 18V, making it ideal for 12V automotive and industrial logic.

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