ICS508MI - 250MHz PECL to CMOS Clock Generator | Renesas
Référence : ICS508MI ✓ ActifICS508MI Présentation
A clock generator is a timing IC that produces a stable, distributed clock signal for the digital blocks of a system. A PECL-to-CMOS converter is a specialised clock-buffer function: positive emitter-coupled logic (PECL, also called ECL) is a high-speed differential-style bipolar logic standard used inside high-speed telecom and datacom equipment, while CMOS is the low-noise, low-power logic family used by most modern ASICs, FPGAs and processors. A converter of this type sits in the hierarchy clock generator > clock buffer > clock and timing IC > integrated circuit, and it is used when a design must translate an ECL/PECL domain clock onto a CMOS domain rail without adding a PLL or changing the fundamental frequency.
Key features of the ICS508MI include a maximum operating frequency of 250 MHz, a single output circuit with no internal PLL, a fixed 1:1 divide ratio between input and output, and a differential-input capable interface. The device operates from a 2.375 V to 5.5 V supply and is specified in the 8-SOIC surface-mount package, with tube packing indicated by the MI ordering suffix.
Architecturally the ICS508MI is deliberately simple. There is no PLL, no VCO and no programmable divider chain, so the output is a buffered and level-shifted replica of the input clock with deterministic phase behaviour and very low added jitter relative to PLL-based solutions. The ICS508 family uses separate supply pins for the PECL input side and the CMOS output side, which allows the converter to be operated at the supply level that best suits each side of the interface, such as 5 V PECL driving a 2.5 V CMOS core.
Typical applications include telecom line-card and cross-connect equipment, network interface cards, SONET/SDH and Ethernet line cards, high-speed backplane distribution, test and measurement instrumentation, and any board that mixes ECL/PECL clocking with CMOS logic.
The key design consideration is supply partitioning: keep the PECL and CMOS supply rails decoupled, terminate PECL inputs with the appropriate bias network, and observe the recommended output termination to avoid edge degradation at 250 MHz.
This page consolidates the ICS508MI specifications, drop-in alternatives, packaging details and practical layout guidance into one reference, adding engineering context that is not in the manufacturer datasheet itself.
Alternatives de remplacement direct pour ICS508MI — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
ICS508CM
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
ICS508ML
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
ICS508
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
ICS508MI Spécifications
| Device Type | Clock Generator IC / PECL to CMOS Converter |
| Maximum Frequency | 250 MHz |
| Input Logic Level | PECL (ECL) |
| Output Logic Level | CMOS |
| Number of Circuits | 1 |
| Input-to-Output Ratio | 1:1 |
| PLL | No |
| Divider / Multiplier | None (1:1 pass-through) |
| Supply Voltage Range | 2.375 V to 5.5 V |
| Differential Input | Supported differential input clocking |
| Boîtier | 8-SOIC (0.154 inch, 3.90 mm width) |
| Type de montage | Surface Mount |
| Series | ICS508 ClockBlocks |
| Packing | Tube |
Guide de configuration des broches du ICS508MI 8-soic (0.154 inch, 3.90 mm width)
Configuration des broches du ICS508MI (boîtier 8-soic (0.154 inch, 3.90 mm width)). La numérotation des broches, les fonctions et les schémas de connexion sont définis dans la fiche technique du fabricant. Consultez-la pour l'empreinte exacte et les directives de soudage.
Aucune donnée de brochage détaillée disponible pour ICS508MI.
Consultez la fiche technique pour la configuration complète des broches.
Applications typiques
ICS508MI convient pour 6 applications: Telecom Line-Card Clock Distribution, Network Interface and Cross-Connect Equipment, High-Speed Backplane and Board-Level Clock Fanout, Test and Measurement Instrumentation, Industrial Control and Data Acquisition Modules, Consumer and Communication Electronics Hybrids.
Telecom Line-Card Clock Distribution
The ICS508MI fits line-card designs where the board receives an ECL-domain reference clock from the backplane and must hand a clean CMOS clock to ASICs, FPGAs and memory. Because the ICS508MI converts PECL to CMOS at 250 MHz with a 1:1 ratio and no internal PLL, the distributed clock stays phase-locked to the backplane reference without the lock-time or jitter penalty of a synthesizer. Separate PECL-side and CMOS-side supply pins let the converter be biased at the ECL level of the shelf while driving CMOS rails locally. The 8-SOIC footprint keeps the converter out of the way of dense routing on modern line-card mezzanines.
Recommandé
Network Interface and Cross-Connect Equipment
In network interface and cross-connect shelves, the system clock usually originates in an ECL/PECL domain while the payload silicon runs on CMOS. The ICS508MI provides the boundary translation in a single 8-SOIC device, delivering up to 250 MHz with no division or multiplication so frequency relationships stay exact. That 1:1 behaviour matters for payload path timing budgets, since no re-referencing or fractional division error is introduced. The absence of a PLL also keeps the device simple to qualify and immune to loop-stability concerns in space-constrained line-card plug-ins.
Recommandé
High-Speed Backplane and Board-Level Clock Fanout
When a 250 MHz ECL clock must be brought onto a board and re-referenced locally, the ICS508MI converts the PECL source into a CMOS clock that can drive CMOS fanout buffers, FPGAs and SerDes blocks. The value is in the single-stage conversion with no PLL overhead, so the output edge and phase relationship track the incoming ECL reference directly. In backplane designs with long ECL traces, the converter can sit close to the receiving ASICs to shorten the CMOS run and contain the ECL impedance-controlled section near the connector. The 8-SOIC package supports placement on either side of the board.
Recommandé
Test and Measurement Instrumentation
Instrumentation and automated test equipment often mixes ECL instrumentation buses with CMOS control logic. The ICS508MI provides a direct PECL-to-CMOS translation path up to 250 MHz, allowing a legacy ECL test head or trigger source to feed modern CMOS counters, comparators and microcontrollers. Using a 1:1 converter rather than a PLL-based generator keeps the trigger relationship to the source deterministic, which matters for repetitive sampling and calibration routines. The single supply range of 2.375 V to 5.5 V also allows one part to cover both 2.5 V and 5 V instrument logic levels.
Recommandé
Industrial Control and Data Acquisition Modules
In industrial data-acquisition modules, a legacy ECL backplane clock can be translated to CMOS for the ADC control logic, FPGA fabric and communications processors using the ICS508MI. Because the converter introduces no frequency multiplication or division, the sampling clock relationship to the converter trigger stays fixed, which supports deterministic multi-channel acquisition. The wide 2.375 V to 5.5 V operating range lets the same device serve both 3.3 V and 5 V sections of a mixed-voltage module. The small SOIC-8 outline also fits dense control boards where a larger quad buffer would not.
Recommandé
Consumer and Communication Electronics Hybrids
Consumer and communication products that combine an ECL-derived or ECL-referenced timing path with CMOS logic can use the ICS508MI to contain the legacy clock domain. A typical case is a video or broadcast module where an upstream ECL timing reference must be conditioned before feeding CMOS video processors. Operating at up to 250 MHz, the ICS508MI keeps the conversion transparent and adds no measurable frequency offset. Its 8-SOIC package and single-channel simplicity also make it easy to place next to the ASIC that needs the clock, shortening the CMOS trace and reducing susceptibility to EMI on consumer boards.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour ICS508MI — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | ICS508CM | ICS508ML | ICS508 |
|---|---|---|---|---|
| Package | 8-SOIC (0.154", 3.90mm Width) | 8-SOIC (0.154", 3.90mm Width) - same | 8-SOIC (0.154", 3.90mm Width) - same | 8-SOIC (0.154", 3.90mm Width) - same |
| Brand | Renesas Electronics | Renesas Electronics | Renesas Electronics | Renesas Electronics |
| Device Type | Clock Generator IC / PECL to CMOS Converter | Clock Generator IC / PECL to CMOS Converter | Clock Generator IC / PECL to CMOS Converter | Clock Generator IC / PECL to CMOS Converter |
| Maximum Frequency | 250 MHz | 250 MHz | 250 MHz | 250 MHz |
| Input / Output Logic | PECL in / CMOS out | PECL in / CMOS out | PECL in / CMOS out | PECL in / CMOS out |
| PLL | No | No | No | No |
| Number of Circuits | 1 | 1 | 1 | 1 |
| Input-to-Output Ratio | 1:1 | 1:1 | 1:1 | 1:1 |
| Supply Voltage Range | 2.375 V to 5.5 V | 2.375 V to 5.5 V | 2.375 V to 5.5 V | 2.375 V to 5.5 V |
Principaux différenciateurs
- Single-stage PECL to CMOS conversion with no PLL and no divider (vs PLL-based clock generator ICs in SOIC-8)
- Split PECL-side and CMOS-side supply pins (vs ICS508CM)
- Narrow-body 8-SOIC footprint with 1.27 mm pitch (vs ICS508ML)
- Wide 2.375 V to 5.5 V operating supply range (vs ICS508CM)
Notes de conception
The ICS508MI uses separate supply pins for the PECL input side and the CMOS output side. Place a dedicated 0.1 uF decoupling capacitor at each supply pin and a bulk capacitor close to the device, keeping both return paths to the same solid ground plane. Because the two domains can run at different logic levels, do not assume a single capacitor can serve both rails - each supply needs its own local decoupling to keep the ECL-side and CMOS-side noise out of each other.
PECL inputs require the correct bias network - typically a Thevenin terminator referenced to the supply rail - and the ECL trace must be routed as a controlled-impedance line with continuous reference. Keep the PECL run short and place the ICS508MI close to the receiving ASIC so the regenerated CMOS clock has the cleanest possible path. At 250 MHz the output rise and fall times are fast enough that the CMOS trace behaves as a transmission line, so review the recommended output termination from the datasheet AC characteristics before finalising the layout.
Do not expect the ICS508MI to synthesise, divide or clean up a clock - it contains no PLL and no divider, so the output is always a 1:1 replica of the input. Two common design errors follow from this: wiring a noisy or drifting reference into the device and expecting the part to correct it, and assuming a missing or floating input will produce a usable clock. Verify the source clock amplitude, duty cycle and jitter at the input pin, and confirm the input is always driven or terminated before power-up.
The ICS508MI is a low-power buffer-class device and is not normally thermally limited in an 8-SOIC outline, but it does dissipate power proportional to switching activity and output load. Estimated: with a 5 V supply, an approximate 30 mA total supply current and a 60% switching activity factor, the average dissipation is on the order of 30 mA x 5 V x 0.6 = 90 mW. Even so, place the part away from hot regulators and provide normal copper spreading so local temperature rise stays well below the grade limit.
Informations de conformité
The ICS508MI is a legacy clock and timing IC from the ICS508 ClockBlocks family; compliance documentation was not part of the manufacturer material reviewed, so RoHS, REACH, lead-free and halogen-free status are recorded as unknown rather than assumed. AEC-Q100 is marked not applicable since the device is not positioned as an automotive-qualified part.