CD4028BF - CMOS BCD-to-Decimal Decoder | Texas Instruments
MPN: CD4028BF ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.5 | $8.50 |
| 10 | $7.25 | $72.50 |
| 100 | $5.95 | $595.00 |
| 500 | $4.8 | $2,400.00 |
| 1,000 | $4.1 | $4,100.00 |
CD4028BF Overview
A BCD-to-decimal decoder is a combinational logic circuit in the CMOS 4000-series family that converts Binary Coded Decimal input codes (0000-1001) into one-of-ten mutually-exclusive active-high outputs. As a member of the decoder/driver category within the broader integrated circuit hierarchy (decoder/driver -> decoder -> logic IC -> semiconductor), it sits alongside address decoders, display drivers, and code converters, providing 1-of-10 fan-out with on-chip input buffering for direct drive of indicator tubes, Nixie displays, and memory-chip select lines.
Key features of the CD4028BF include 4 buffered inputs with standard CMOS B-series noise immunity, 10 decoded outputs that are mutually exclusive (only one HIGH at a time), 3 additional outputs Y2/Y4/Y8 that decode the binary-to-octal function for codes 10-15, and quiescent current of approximately 0.5 uA at 5V VDD. The CDIP-16 ceramic package provides hermetic sealing for military and aerospace programs requiring extended reliability under thermal and mechanical stress. Per the TI CD4028B-MIL product page, the part meets all requirements of JEDEC Tentative Standard No. 13B for B-Series CMOS Devices.
The CD4028BF is built on a 4000B-series CMOS process with P-channel and N-channel enhancement MOSFETs implementing the NAND/NOR decode matrix, followed by output buffers sized to source/sink approximately 1 mA at 5V VDD. The buffered inputs prevent input loading on the driving logic, allowing direct connection to standard TTL or CMOS sources even when VDD exceeds Vih(TTL). The decoded outputs are non-latching and follow the input code in real time, which simplifies memory-chip-select decoding where a static address must be continuously asserted.
Typical applications include indicator-tube (Nixie) drivers for vintage instrumentation displays, memory-chip select decoding for systems requiring more than four chip enables, address decoding for I/O expansion, decimal readout for digital meters, and code conversion from BCD/binary to one-hot representations. The wide 3V to 18V supply range supports both 5V TTL and 15V CMOS system environments without level shifters.
When designing with the CD4028BF, ensure VDD decoupling with a 0.1 uF ceramic capacitor placed close to pin 16 (VDD), tie unused inputs to VDD or GND to prevent shoot-through current, and verify that output sink/source current stays within the 1 mA limit when driving high-current loads such as Nixie cathodes - in those cases add a discrete transistor buffer stage.
This page synthesizes distributor pricing, MIL-spec drop-in alternatives, pinout reference data, and PCB design notes not found in the bare datasheet, enabling engineers to source, qualify, and lay out the CD4028BF faster.
Drop-in alternatives for CD4028BF — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
CD4028BF/3
✅ Drop-In📋 Reference alternative (not in catalog)
CD4028BE
✅ Drop-In📋 Reference alternative (not in catalog)
CD4028BDNSR
✅ Drop-In📋 Reference alternative (not in catalog)
CD4028BNSR
✅ Drop-In📋 Reference alternative (not in catalog)
CD4028BDR
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
CD4028BF Maximum Ratings & Electrical Characteristics
| Function | BCD-to-Decimal or Binary-to-Octal Decoder/Driver |
| Technology | CMOS 4000B-Series |
| Number of Inputs | 4 (A, B, C, D) |
| Number of Outputs | 10 active-HIGH decoded + 3 binary-to-octal |
| Output Configuration | Active-HIGH, non-inverting, non-latching |
| Supply Voltage (VDD) | 3 V to 18 V |
| Parametric Supply Ratings | 5 V, 10 V, 15 V |
| Quiescent Current (typ @ 5V) | 0.5 uA |
| Operating Temperature Range | -55 C to +125 C |
| Package | 16-pin CDIP (J) |
| Mounting Type | Through-Hole |
| MSL Level | Not applicable (through-hole) |
| Compliance Standard | JEDEC Standard No. 13B (B-Series CMOS) |
CD4028BF Pin Configuration
| Pin 1 | Q5 — Active-HIGH decoded output for BCD input 0101 |
| Pin 2 | Q2 — Active-HIGH decoded output for BCD input 0010 |
| Pin 3 | Q6 — Active-HIGH decoded output for BCD input 0110 |
| Pin 4 | Q9 — Active-HIGH decoded output for BCD input 1001 |
| Pin 5 | Q7 — Active-HIGH decoded output for BCD input 0111 |
| Pin 6 | Q8 — Active-HIGH decoded output for BCD input 1000 |
| Pin 7 | Q1 — Active-HIGH decoded output for BCD input 0001 |
| Pin 8 | VSS — Ground (0 V) |
| Pin 9 | Q0 — Active-HIGH decoded output for BCD input 0000 |
| Pin 10 | Q3 — Active-HIGH decoded output for BCD input 0011 |
| Pin 11 | Q4 — Active-HIGH decoded output for BCD input 0100 |
| Pin 12 | A — BCD input bit A (LSB) |
| Pin 13 | B — BCD input bit B |
| Pin 14 | C — BCD input bit C |
| Pin 15 | D — BCD input bit D (MSB) |
| Pin 16 | VDD — Positive supply voltage (3 V to 18 V) |
Typical Applications
CD4028BF is suitable for 6 applications: Nixie Tube Indicator Driver, Memory Chip-Select Decoder, BCD-to-Decimal Code Conversion, Address Decoding for I/O Expansion, Binary-to-Octal Decoder (1-of-8), Aerospace and Defense Avionics.
Nixie Tube Indicator Driver
The CD4028BF drives Nixie tube cathodes in vintage-style displays, instrumentation, and retro computing projects. Its ten active-HIGH decoded outputs map directly to digits 0-9 of a BCD input, allowing a microcontroller or BCD counter to select one cathode at a time while the anode is held at high voltage. The wide 3 V to 18 V supply range supports typical Nixie 150 V anode supplies via external high-voltage transistor drivers. Per TI CD4028B-MIL documentation, the part meets JEDEC Standard No. 13B for B-Series CMOS Devices and the -55 C to +125 C MIL temperature range ensures stable decoding in thermally demanding environments.
Recommended
Memory Chip-Select Decoder
The CD4028BF decodes a 4-bit address bus into one of ten mutually-exclusive chip-select lines for memory banks, register files, or peripheral arrays in 8-bit and 16-bit microprocessor systems. Each decoded output maps to a unique 4-bit address pattern, allowing one decoder to replace up to ten discrete AND-gate chip-select networks and reduce PCB area. The buffered inputs prevent loading on the address lines, and the active-HIGH outputs can directly drive CS pins of CMOS memory ICs without inverters. Per the TI datasheet, output sink/source capability of approximately 1 mA at 5 V supports direct CMOS-memory interface.
Recommended
BCD-to-Decimal Code Conversion
The CD4028BF performs direct BCD-to-decimal code conversion in digital panel meters, frequency counters, and industrial displays that accept BCD from upstream logic but need one-of-ten outputs to drive LED bar-graph arrays, relay matrices, or numeric indicator panels. The non-inverting output polarity preserves the BCD code without inversion, simplifying the downstream driver stage. The 3 V to 18 V supply range supports both 5 V TTL-driven front-ends and 12 V/15 V industrial control environments without level translation. Per TI documentation, the decoder logic is combinational and follows the input code in real time without latching.
Recommended
Address Decoding for I/O Expansion
The CD4028BF decodes upper address lines for I/O port expansion in 8080/Z80/6502 systems where multiple peripherals share a common I/O address space. Mapping each decoded output to a distinct I/O port or peripheral chip-select enables up to ten devices on a single 4-bit address slice, eliminating the need for discrete diode-OR or gate-array decoding networks. The CMOS 4000B-series noise margin ensures reliable decoding in noisy industrial environments. Per the TI CD4028B-MIL product page, the MIL temperature grade is qualified for many industrial applications.
Recommended
Binary-to-Octal Decoder (1-of-8)
Using only inputs A, B, C and ignoring D, the CD4028BF becomes a 3-to-8 binary decoder with active-HIGH outputs that can drive logic-level indicators, relay coils, or low-current loads. This binary-to-octal mode is useful for control panels, test equipment, and logic analyzers that need to visualize binary states. The supplementary Y2/Y4/Y8 outputs provide direct binary-weight access for codes 10-15, enabling hybrid decoding schemes. Per TI CD4028B datasheet, the buffered inputs and decoded outputs maintain signal integrity across the full 3 V to 18 V supply range.
Recommended
Aerospace and Defense Avionics
The CD4028BF is qualified for aerospace and defense avionics programs that require MIL-spec temperature range (-55 C to +125 C) and the hermetic 16-pin ceramic DIP package. The MIL-spec decoder/driver handles mission-critical signal routing in flight-control systems, navigation displays, and radar signal processing where commercial-grade parts are not qualified. The JEDEC Standard No. 13B compliance per TI CD4028B-MIL documentation provides assurance of long-term manufacturer support and obsolescence management. The hermetic package also resists humidity and contamination in extended-duty aerospace deployments.
Recommended
Recommended Products Summary
Engineering reference data for CD4028BF — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | CD4028BF/3 | CD4028BE | CD4028BDNSR | CD4028BNSR | CD4028BDR |
|---|---|---|---|---|---|---|
| Package | 16-CDIP (J) ceramic | 16-CDIP (J) ceramic - same | 16-PDIP plastic | 16-SOIC (NS) | 16-SOIC (NS) | 16-SOIC (D) |
| Brand | Texas Instruments | Harris Corporation | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Function | BCD-to-Decimal Decoder | BCD-to-Decimal Decoder | BCD-to-Decimal Decoder | BCD-to-Decimal Decoder | BCD-to-Decimal Decoder | BCD-to-Decimal Decoder |
| Supply Voltage Range | 3 V to 18 V | 3 V to 18 V | 3 V to 18 V | 3 V to 18 V | 3 V to 18 V | 3 V to 18 V |
| Operating Temperature | -55 C to +125 C (MIL) | -55 C to +125 C (MIL) | 0 C to +70 C (commercial) | -55 C to +125 C | -55 C to +125 C | -55 C to +125 C |
| Number of Outputs | 10 decoded + 3 binary-to-octal | 10 decoded + 3 binary-to-octal | 10 decoded + 3 binary-to-octal | 10 decoded + 3 binary-to-octal | 10 decoded + 3 binary-to-octal | 10 decoded + 3 binary-to-octal |
| Mounting Type | Through-Hole (ceramic DIP) | Through-Hole (ceramic DIP) | Through-Hole (plastic DIP) | Surface Mount (SOIC) | Surface Mount (SOIC) | Surface Mount (SOIC) |
| JEDEC Compliance | Yes (Std. No. 13B) | Yes | Yes | Yes | Yes | Yes |
Key Differentiators
- MIL-spec temperature range and hermetic ceramic package (vs CD4028BE)
- Multiple decoded outputs plus binary-to-octal outputs (vs CD4028BE)
- Buffered inputs for direct TTL/CMOS interface (vs Discrete AND-gate decoder networks)
Design Notes
Decouple VDD (pin 16) to VSS (pin 8) with a 0.1 uF ceramic capacitor placed within 5 mm of the package. The CMOS 4000B-series has low quiescent current (typically 0.5 uA at 5 V) but switching transients during decode transitions can cause brief current spikes; the bypass capacitor suppresses these transients and prevents logic noise coupling into adjacent analog circuits.
Unused BCD inputs (A, B, C, D on pins 12-15) MUST be connected to either VDD or VSS, never left floating. A floating input can drift into the linear region between logic thresholds, causing shoot-through current in the input buffer stage, increased quiescent current draw, and oscillation that can propagate into the decoded outputs. Tie unused inputs directly to VDD or VSS at the package pin.
Output sink/source current of the CD4028BF is approximately 1 mA at 5 V VDD. When driving high-current loads such as Nixie tube cathodes, LED arrays, or relay coils, use the decoder outputs as control signals to a discrete transistor (e.g., MPSA42 NPN high-voltage transistor for Nixie cathodes) or a ULN2003 driver array. Directly driving >10 mA loads from the decoder outputs can damage the output buffer over time.
Compliance Information
Compliance status not explicitly stated in verified web data for the CD4028BF MIL-spec ceramic-DIP variant; the JEDEC Standard No. 13B compliance is the only verified compliance note. AEC-Q100 is not applicable as this is a logic IC, not an automotive-grade analog IC.
