CD4585BD - 4-Bit Magnitude Comparator | Texas Instruments
MPN: CD4585BD ✓ ActiveCD4585BD Overview
A magnitude comparator is a combinational logic device that examines corresponding bits of two multi-bit operands and produces an ordering result. The CD4585BD belongs to the CMOS logic family, where CMOS means complementary metal-oxide-semiconductor. Its hierarchy extends from a digital comparator IC to a logic IC, integrated circuit, and semiconductor. The device is useful whenever a system must determine the relationship between two numerical values without relying on a processor.
The CD4585BD supports supply voltages from 3 V to 18 V, operates across a military temperature range of -55 °C to +125 °C, and provides a 160 ns propagation delay at 15 V with a 50 pF load. Its active-high A<B, A=B, and A>B outputs report the comparison result directly. The specified 100 µA supply current supports low-power logic designs, while the 6.8 mA output-current figure defines the available output drive in the cited product data.
Cascading inputs extend the comparison to more than four bits. The equal, greater-than, and less-than cascade paths allow multiple CD4585 devices to compare two larger words. Designers must connect unused inputs to defined logic levels and account for propagation delay through each cascade stage when evaluating system timing.
Typical uses include digital sorting and ranking, address and threshold comparison, BCD arithmetic control, test-equipment decision logic, industrial control sequencing, and embedded systems that require a hardware ordering function. Its military temperature range and through-hole CDIP-16 package also make it suitable for legacy and ruggedized equipment where surface-mount alternatives are unsuitable.
For reliable operation, keep every supply pin within the 3 V to 18 V range and use the manufacturer's recommended operating conditions. Decoupling capacitors should be placed close to the supply pins, while all digital inputs should remain driven to valid CMOS levels. Propagation-delay accumulation and output contention require particular attention when several devices are cascaded.
This page consolidates the verified distributor specifications, pricing context, a same-family drop-in assessment, and practical implementation guidance. It also separates documented electrical values from unavailable parameters rather than filling gaps with estimated or invented specifications.
Drop-in alternatives for CD4585BD — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
CD4585BM
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
CD4585BD Maximum Ratings & Electrical Characteristics
| Product Type | 4-bit magnitude comparator |
| Logic Family | CMOS |
| Supply Voltage Range | 3 V to 18 V |
| Operating Temperature Range | -55 °C to +125 °C |
| Propagation Delay | 160 ns at 15 V and 50 pF load |
| Supply Current | 100 µA |
| Output Current | 6.8 mA |
| Comparison Inputs | 8 inputs: A3-A0 and B3-B0 |
| Comparison Outputs | 3 active-high outputs: A<B, A=B, and A>B |
| Cascading Inputs | 3 inputs for greater-than, equal-to, and less-than cascading |
| Supported Number Formats | Binary or BCD 4-bit words |
| Package | 16-pin CDIP through-hole package |
| Pin Count | 16 pins |
| Mounting Type | Through-hole |
| Temperature Grade | Military |
| Output Polarity | Active high |
CD4585BD Pin Configuration
| Pin 1 | A0 — Least-significant A comparison input |
| Pin 2 | B0 — Least-significant B comparison input |
| Pin 3 | A1 — A1 comparison input |
| Pin 4 | B1 — B1 comparison input |
| Pin 5 | A2 — A2 comparison input |
| Pin 6 | B2 — B2 comparison input |
| Pin 7 | A3 — Most-significant A comparison input |
| Pin 8 | B3 — Most-significant B comparison input |
| Pin 9 | A=B — Active-high equal comparison output |
| Pin 10 | A>B — Active-high greater-than comparison output |
| Pin 11 | A<B — Active-high less-than comparison output |
| Pin 12 | VSS — Ground reference |
| Pin 13 | A<B — Less-than cascading input |
| Pin 14 | A=B — Equal cascading input |
| Pin 15 | A>B — Greater-than cascading input |
| Pin 16 | VDD — Positive supply input |
Typical Applications
CD4585BD is suitable for 6 applications: Digital Sorting and Ranking Systems, BCD Counter Threshold Control, Address and Threshold Comparison, Ruggedized Industrial Control Logic, Test and Measurement Decision Logic, Aerospace and Defense Logic Modules.
Digital Sorting and Ranking Systems
The CD4585BD is useful when hardware must determine the ordering of two 4-bit values before data is moved, stored, or processed. Its A<B, A=B, and A>B outputs provide a direct magnitude relationship, avoiding comparator software and reducing the delay between a value change and the associated control decision. The verified 160 ns propagation delay at 15 V and 50 pF is appropriate for moderate-speed sorting and arbitration logic. When comparing values beyond four bits, multiple CD4585 devices can be cascaded through their less-than, equal-to, and greater-than inputs. Engineers should include the cumulative propagation delay of each cascaded stage and ensure that the selected data remains stable while the comparison result propagates.
Recommended
BCD Counter Threshold Control
The CD4585BD can compare a 4-bit BCD count against a fixed threshold and generate control signals when the count is below, equal to, or above the limit. This makes it suitable for decade-counter sequencing, industrial timing systems, and decimal instrumentation. Because the device supports BCD as well as binary operands, the threshold input can represent a decimal digit without converting it to another numeric format. The 6.8 mA output-current specification provides useful drive for CMOS logic, while the 100 µA supply-current figure supports low-power operation. Designers should debounce or synchronize asynchronous count transitions when a changing BCD bus could briefly produce an unintended comparison result.
Recommended
Address and Threshold Comparison
The CD4585BD can compare a 4-bit address or index against a threshold and directly indicate whether the value is below, equal to, or above the selected limit. Such hardware comparisons are useful in memory-mapped control, legacy processor peripherals, industrial sequencers, and equipment where a decoded address must trigger a deterministic action. The active-high outputs can be combined with existing gate logic or routed into a system-control bus. At a 15 V supply and 50 pF load, the specified 160 ns propagation delay provides a concrete timing budget for address qualification. The design must guarantee stable address data during that interval and account for output loading from any additional CMOS gates.
Recommended
Ruggedized Industrial Control Logic
The CD4585BD's -55 °C to +125 °C operating range and 16-pin CDIP through-hole package suit ruggedized industrial control equipment, test systems, and legacy production machinery. The comparator can perform magnitude decisions independently of a microcontroller, providing hardware ordering for alarms, interlocks, and sequencing decisions. Its 3 V to 18 V supply range allows operation across legacy CMOS voltage domains, subject to the manufacturer's absolute-maximum limits. Through-hole construction is particularly valuable where repeated mechanical shock, vibration, or repair cycles make small surface-mount packages less desirable. The principal design trade-off is the 160 ns specified propagation delay at 15 V and 50 pF, which must be included in timing analyses.
Recommended
Test and Measurement Decision Logic
In test and measurement equipment, the CD4585BD can compare a 4-bit range code, attenuation setting, or instrument state against a stored threshold and produce explicit less-than, equal-to, and greater-than indications. Those outputs can support range selection, calibration checks, or front-panel state validation without a software comparison loop. The active-high outputs make the results straightforward to combine with additional CMOS logic, while the 3 V to 18 V operating range supports integration with older instrument boards. Designers should account for the 160 ns delay at 15 V and 50 pF when coordinating the comparison result with control registers. A single device covers four bits, so wider comparisons require carefully cascaded additional stages.
Recommended
Aerospace and Defense Logic Modules
The CD4585BD's military temperature range of -55 °C to +125 °C makes it applicable to temperature-demanding comparison tasks in aerospace, defense, and ruggedized legacy modules. It can compare binary or BCD words for navigation, telemetry, test sequencing, or subsystem control and provides dedicated active-high ordering outputs rather than requiring a general-purpose processor. The 16-pin CDIP package supports through-hole assembly in equipment designed around larger, field-serviceable logic packages. Qualification requirements still vary by program, so engineers should verify the exact ordering code, quality documentation, and applicable procurement requirements. Timing analysis should include the 160 ns propagation delay at 15 V and 50 pF plus the delay of any cascaded comparator.
Recommended
Recommended Products Summary
Engineering reference data for CD4585BD — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | CD4585BM |
|---|---|---|
| Brand | Texas Instruments | Texas Instruments |
| Package | CDIP-16 | CDIP-16 |
| Function | 4-bit magnitude comparator | 4-bit magnitude comparator |
Key Differentiators
- Wide verified operating range (vs CD4585BM)
- Military-temperature through-hole construction (vs CD4585BE)
- Complete ordering information in one design decision (vs CD4585BM)
Design Notes
Treat the A and B buses as synchronous data for comparison timing. The verified propagation delay is 160 ns at 15 V with a 50 pF load, so the input value must remain stable for the required comparison interval. When the compared value changes near a decision boundary, add external register or latch staging to prevent propagation between the comparator output and the surrounding control logic. Cascaded comparisons require the cumulative delay of every stage rather than only the 160 ns figure for one device.
Place the supply-decoupling capacitor close to pin 16 and ground return close to pin 12. Keep the A and B input traces short enough to minimize capacitive loading and ringing, especially because the 160 ns propagation-delay specification is stated at a 50 pF load. Provide a solid ground reference on the board and avoid routing unrelated high-current signals between the through-hole device and its bypass capacitor. Confirm the final orientation against the manufacturer's package drawing before insertion.
Do not connect a comparison output directly to another device's output, and do not allow unused CMOS inputs to float. The cascading inputs on pins 13 through 15 must be driven to valid logic states or handled according to the manufacturer's cascade recommendations. Also verify the package suffix before substitution: the verified CD4585BE listing uses a 16-pin PDPIP package and is not a physical drop-in match for the CDIP-16 CD4585BD.
Compliance Information
The supplied verified data does not state RoHS, REACH, lead-free, halogen-free, or conflict-minerals status. AEC-Q100 is marked not applicable because the device is identified as a general-purpose military-temperature logic comparator rather than an automotive-qualified part.
