Part A
ADF4156BRUZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4703 PCS
- Package
- TSSOP-16
- Series
- Clock-Timing - Clock Generators, PLLs, Frequency Synthesizers
Replacement verdict
Compatible functional replacement candidate
The ADF4156BRUZ and ADF4112BRU are both single-channel integer-N PLL frequency synthesizers in a 16-lead TSSOP package, sharing a common footprint and 3 V supply range, so the ADF4156BRUZ can serve as a functional replacement candidate for the ADF4112BRU. However, the two devices differ in maximum operating frequency, phase detector frequency, and reference input characteristics, so the replacement must be validated against the target frequency plan and loop filter design before adoption.
Package Type
High match
Supply Voltage Range
High match
Maximum Operating Frequency
Validation required
Phase Detector Frequency
Validation required
Parts at a glance
Part B
ADF4112BRU
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4577 PCS
- Package
- TSSOP-16
- Series
- Clock-Timing - Clock Generators, PLLs, Frequency Synthesizers
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADF4156BRUZ | ADF4112BRU | Why it matters |
|---|---|---|---|
| Maximum RF Input Frequency | 6 GHz | 3 GHz | Determines the highest frequency the PLL can synthesize; the ADF4156 supports higher-frequency applications. |
| Maximum PFD Frequency | 32 MHz | 55 MHz | Higher phase-frequency detector rates allow wider loop bandwidths and faster settling, affecting lock time and phase noise. |
| Fractional-N Capability | Yes (fractional-N) | No (integer-N) | Fractional-N allows finer frequency resolution and higher comparison frequencies, which is a fundamental architectural difference for substitutability. |
| Normalized Phase Noise Floor | -216 dBc/Hz | -212 dBc/Hz | Lower phase noise floor improves spectral purity of the synthesized signal, critical for RF system performance. |
| Supply Voltage Range | 2.7 V to 3.3 V | 2.7 V to 5.5 V | Wider supply range offers flexibility in system power design; the ADF4112 can operate at higher supply voltages. |
| Package Type | 16-Lead TSSOP | 16-Lead TSSOP | Package footprint and pinout affect board layout and drop-in compatibility. |
| Operating Temperature Range | -40°C to +85°C | -40°C to +85°C | Confirms both parts are rated for the same industrial temperature environment. |
| Programmable Charge Pump Current | Up to 5 mA | Up to 5 mA | Charge pump current affects loop filter design and loop dynamics; matching values ease substitution. |
| Number of Pins | 16 | 16 | Pin count influences package compatibility and PCB layout considerations. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADF4156BRUZ | ADF4112BRU |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Type | Fractional N Synthesizer (RF) | Clock/Frequency Synthesizer (RF) |
| PLL | Yes | Yes |
| Input | CMOS, TTL | CMOS, TTL |
| Output | Clock | Clock |
| Number of Circuits | 1 | 1 |
| Ratio - Input: Output | 2:1 | 2:1 |
| Differential - Input: Output | Yes/No | Yes/No |
| Frequency - Max | 6.2GHz | 3GHz |
| Divider / Multiplier | Yes/Yes | Yes/No |
| Voltage - Supply | 2.7V ~ 3.3V | 2.7V ~ 5.5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
Frequently asked questions
What are the key differences between the ADF4156BRUZ and ADF4112BRU?
The ADF4156BRUZ is a fractional-N PLL frequency synthesizer with an integrated VCO, operating up to 6 GHz, while the ADF4112BRU is an integer-N PLL synthesizer without an integrated VCO, operating up to 3 GHz. The ADF4156BRUZ supports fractional-N operation for finer frequency resolution, whereas the ADF4112BRU uses integer-N architecture requiring a lower reference comparison frequency for fine steps.
Are the ADF4156BRUZ and ADF4112BRU pin-compatible?
No. Both devices are offered in 20-lead TSSOP packages, but their pin functions and internal architectures differ. The ADF4156BRUZ includes RF input and charge pump pins configured for fractional-N operation, while the ADF4112BRU has a different pin assignment for its integer-N architecture. They are not direct drop-in replacements.
What is the maximum operating frequency of each device?
The ADF4156BRUZ operates with an RF input up to 6 GHz. The ADF4112BRU operates with an RF input up to 3 GHz. Designs requiring frequencies above 3 GHz must use the ADF4156BRUZ or an external prescaler with the ADF4112BRU.
Which device supports fractional-N synthesis?
Only the ADF4156BRUZ supports fractional-N synthesis, allowing frequency resolution finer than the phase detector comparison frequency. The ADF4112BRU is an integer-N synthesizer, so its output frequency step equals the phase detector comparison frequency divided by the prescaler ratio.
Do both devices require an external VCO?
No. The ADF4156BRUZ integrates a VCO on-chip, reducing external component count and board area. The ADF4112BRU does not include an integrated VCO and requires an external VCO or VCO module connected to its charge pump output.
What supply voltage do the ADF4156BRUZ and ADF4112BRU require?
Both devices operate from a nominal 3.0 V to 3.6 V supply, with a typical operating voltage of 3.3 V. Designers should verify the exact supply range against the respective manufacturer datasheet for the specific grade and operating conditions.
Can the ADF4112BRU be used as a direct substitute for the ADF4156BRUZ in an existing design?
No. The devices differ in architecture (integer-N vs fractional-N), maximum RF input frequency (3 GHz vs 6 GHz), VCO integration, and pin configuration. A direct substitution would require redesign of the loop filter, reference frequency plan, and PCB layout, and is not supported without full validation against both datasheets.