ICS291PG - 200MHz Triple-PLL Spread-Spectrum Clock | Renesas
MPN: ICS291PG ✗ End of LifeICS291PG Overview
A spread-spectrum clock synthesizer is a clock-generation IC that varies clock timing over a programmed range to reduce peak electromagnetic emissions. This technique is useful in systems where reducing concentrated electromagnetic interference helps improve signal integrity and regulatory compliance. The ICS291PG is a clock/frequency synthesizer IC with one clock-generation circuit, PLL functionality with bypass, and an input that can be a clock or crystal.
The ICS291PG is associated with clock generation, frequency synthesis, triple-PLL architecture, programmable spread spectrum, multiple output clocks, reference outputs, and CMOS interface support. Its maximum frequency is 200 MHz, and its listed output ratio range is 1 to 6. These characteristics make it relevant to communication equipment, storage systems, computing platforms, and other systems requiring multiple synchronized clocks from a common reference.
The device uses a field-programmable configuration approach, allowing clock multiplication, division, spread-spectrum modulation, and output routing to be configured for a particular board requirement. The PLL-bypass path is important when a system needs to preserve a reference clock during startup, test, or mode transitions. Multiple outputs can reduce the need for separate clock-generation components while supporting reference and forwarded clock requirements.
Typical implementation involves supplying a stable reference clock or crystal, configuring the internal PLL and output dividers, and routing each CMOS clock output to the relevant subsystem. Board-level design should account for trace impedance, return paths, clock jitter, output loading, and decoupling. Keep clock traces short where practical, provide continuous reference planes, and maintain a solid ground return beneath high-frequency clock routing.
The ICS291PG is best suited to designs needing multiple clocks, programmable frequency relationships, or spread-spectrum clock generation within a compact surface-mount package. For a new design, verify the complete electrical limits, configuration method, pin-level signal names, and timing specifications in the current manufacturer datasheet before releasing production layouts.
Drop-in alternatives for ICS291PG — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
291PGLF
✅ Drop-In📋 Reference alternative (not in catalog)
ICS291PGLF
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ICS291PG-T
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ICS291PG-I
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ICS291PG-HT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
ICS291PG Specifications
| Product Type | Clock/Frequency Synthesizer IC |
| PLL | Yes with Bypass |
| Input Type | Clock, Crystal |
| Output Type | CMOS |
| Maximum Frequency | 200 MHz |
| Number of Circuits | 1 |
| Input-to-Output Ratio | 1:6 |
| PLL Architecture | Triple PLL |
| Spread Spectrum | Field Programmable |
| Number of Outputs | Up to 6 high-quality, high-frequency clock outputs |
| Reference Outputs | Multiple reference clocks |
| Package | 20-TSSOP (0.173 inch, 4.40 mm width) |
| Mounting Type | Surface Mount |
ICS291PG 20-tssop (0.173 inch, 4.40 mm width) Pin Configuration Guide
Pin configuration for ICS291PG (20-tssop (0.173 inch, 4.40 mm width) package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for ICS291PG.
Refer to the datasheet for full pin configuration.
Typical Applications
ICS291PG is suitable for 6 applications: Communications Equipment Clock Trees, Processor and Computer Platform Clocks, Storage and Interface Timing, Industrial Automation Control, Test and Measurement Equipment, Audio and Video Clock Distribution.
Communications Equipment Clock Trees
The ICS291PG fits communications equipment that needs several related clocks from one reference. Its triple-PLL architecture, maximum 200 MHz frequency, CMOS outputs, and support for up to six clocks allow a board to generate reference and forwarded signals for transceivers, processors, memory, or interface controllers. The clock or crystal input supports both active-oscillator and crystal-based architectures. Spread-spectrum programming can reduce peak spectral concentration when the system must limit radiated emissions, while PLL bypass provides a controlled transition path during startup or test. The design should still validate output loading, jitter, supply requirements, and the complete pin configuration against the current manufacturer datasheet.
Recommended
Processor and Computer Platform Clocks
The ICS291PG is applicable to processor platforms where multiple domain clocks must be derived from a common source. The programmable PLL and output structure can provide several CMOS clock signals, while the listed 200 MHz maximum frequency supports a broad range of interface and peripheral timing requirements. In a desktop, industrial computer, or embedded controller, the device can help organize clock routing and reduce the number of separate oscillator packages. Spread-spectrum operation may be useful when reducing discrete spectral peaks matters, but the exact modulation range and jitter behavior must be checked. PCB implementation should preserve continuous return paths and minimize clock branch discontinuities.
Recommended
Storage and Interface Timing
The ICS291PG can support storage controllers and high-speed interface timing where multiple clocks must remain related to one reference. Its up-to-six outputs provide a way to distribute reference and forwarded clocks among memory, serial interfaces, and digital logic, while the 200 MHz maximum frequency is relevant to common system clocking requirements. The CMOS output type is compatible with conventional digital clock routing when loading and termination are properly designed. For a storage product, validate read-clock and write-clock timing, reference stability, spread-spectrum limits, and all clock ratios before selecting the part. Keep sensitive clock traces short and route them over a continuous ground plane to reduce susceptibility to noise and reflections.
Recommended
Industrial Automation Control
The ICS291PG is suitable for industrial automation systems that need deterministic clock distribution across controllers, sensors, and communication modules. The single clock or crystal input provides a reference source, while multiple outputs can support processor, serial, and timing domains. Programmable spread spectrum may help reduce narrowband emissions in equipment operating near sensitive RF or measurement systems. Because industrial systems can involve long traces and multiple clock loads, the implementation should check output drive, fanout, termination, and power-supply noise. A solid ground reference, short clock routes, and careful isolation from switching regulators will help preserve clock quality throughout the enclosure.
Recommended
Test and Measurement Equipment
The ICS291PG can be used in test and measurement equipment when several internally related clock outputs are needed across analog, digital, and communication sections. Its triple-PLL design, CMOS outputs, programmable spread-spectrum capability, and maximum 200 MHz frequency provide a flexible clock foundation for instrument control and signal-chain synchronization. Spread-spectrum operation should be configured deliberately because measurement accuracy can be affected by timing uncertainty and jitter. The design team should compare the required frequency accuracy, jitter, output loading, and spectral limits, then use controlled grounding and short return paths. The exact programming interface and timing margins must be confirmed in the manufacturer datasheet.
Recommended
Audio and Video Clock Distribution
The ICS291PG may be selected for audio or video equipment that needs multiple synchronized digital clock outputs while reducing discrete EMI peaks. Its multiple reference outputs, CMOS interface, programmable PLL, and spread-spectrum feature can support clock distribution around converters, control logic, and communications sections. The implementation must ensure that spread-spectrum modulation does not violate the timing margins of the particular audio or video interface. For high-speed video paths, check output jitter, trace loss, termination, and impedance continuity carefully. The device is best used as a central clock source when the system benefits from programmable relationships and flexible output routing rather than a single fixed oscillator.
Recommended
Recommended Products Summary
Engineering reference data for ICS291PG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | 291PGLF | ICS291PGLF | ICS291PG-T | ICS291PG-I | ICS291PG-HT |
|---|---|---|---|---|---|---|
| Package | 20-TSSOP (0.173 inch, 4.40 mm width) | 20-TSSOP | 20-TSSOP | 20-TSSOP | 20-TSSOP | 20-TSSOP |
| Brand | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics |
Key Differentiators
- Multiple programmable clock outputs from one device (vs ICS291PGLF)
- Field-programmable spread-spectrum operation (vs 291PGLF)
- Maximum 200 MHz clock capability (vs ICS291PG-T)
- PLL bypass supports controlled clock transitions (vs ICS291PG-I)
Design Notes
Place the reference-clock input and decoupling connections according to the manufacturer’s recommended layout. Keep the reference path short, preserve a continuous ground return, and place bypass capacitors close to the device supply pins. Clock outputs should route over an uninterrupted reference plane, with output series termination selected from the actual load, trace impedance, and edge-rate requirements rather than added by default.
Validate the complete clock network with the intended output load, trace length, connector, and downstream receiver. The ICS291PG can generate up to six outputs, so fanout and branch topology can affect edge quality even when each individual output appears within specification. Check rise and fall times, overshoot, ringing, jitter, and timing margin using the final board rather than relying only on a schematic-level calculation.
Use spread-spectrum programming as an EMI-control tool, not as a substitute for controlled layout. Verify the modulation range, center frequency, update rate, and resulting emissions using the final enclosure, cables, power supply, and neighboring circuitry. Keep switching regulators and high-current paths away from the reference input, and maintain short ground returns so spread-spectrum energy is not redistributed by unintended board resonances.
Do not infer pin functions from the product category alone. Confirm pin 1 orientation, power pins, ground pins, configuration pins, PLL bypass behavior, and each clock output in the current manufacturer datasheet before schematic capture or PCB release. Also confirm whether a proposed suffix changes temperature grade, packing, or ordering information. A package name alone does not prove drop-in electrical compatibility.
Compliance Information
The available product information does not state compliance declarations or automotive qualification status. Request the current manufacturer environmental and quality documentation before using the ICS291PG in a regulated design.
