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Semtech Corporation ACS1790IMLTRT
- Part No.:
- ACS1790IMLTRT
- Manufacturer:
- Semtech Corporation
- Package:
- 24-VFQFN Exposed Pad
- Datasheet:
-
ACS1790IMLTRT.pdf
- Description:
- IC FREQ SYNTH 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,952
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Product details
Overview
ACS1790IMLTRT from Semtech is a programmable PLL frequency synthesizer with integrated 2.3–2.7 GHz VCO, delivering ultra-fine 1 ppb frequency resolution and dual LVPECL/LVCMOS outputs (10 MHz–200 MHz and 2 kHz–125 MHz). It supports Synchronous Ethernet, SONET/SDH, and 1G/10G Ethernet clocking with RMS jitter as low as 0.11 ps (XAUI mask) and operates from 3.0–3.6 V supply.
For engineers reviewing the ACS1790IMLTRT datasheet, pinout, applications, or equivalent options, this device is selected for high-stability timing in telecom infrastructure where low-jitter, I²C-programmable synthesis with lock detect and dual-output flexibility are required.
Technical Context
The ACS1790IMLTRT implements a fully self-contained VCO-based PLL with fractional-N feedback divider enabling sub-Hz frequency resolution. Its architecture includes independent O-, B-, P-, and T-dividers to route VCO output to OUT1 (LVPECL), OUT2 (LVCMOS), and FBCLK (LVCMOS feedback clock).
It integrates phase-and-frequency detection, loop filtering, and output stage control with hardware-configurable reset behavior (via OSCFSEL0/1, MODE pins) and software control via I²C interface supporting four slave addresses. Lock detection (LD) is provided as open-drain output with automatic calibration over ±500 ppm tuning range without relock.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCO Frequency Range | 2.3–2.7 GHz - sets fundamental synthesis range; enables wide output coverage via integer/fractional division |
| OUT1 Output Type | LVPECL differential (OUT1P/OUT1N) - supports high-speed clock distribution with controlled impedance termination |
| OUT2 Output Range | 2 kHz–125 MHz LVCMOS - configurable slew rate and 1.8/2.5/3.3 V supply support for mixed-voltage system interfacing |
| RMS Jitter (XAUI) | 0.11 ps (1.875 MHz–20 MHz) - meets IEEE 802.3-2008 Clause 47 mask for 10G serial links |
| Reference Spurs | < −67 dBc - ensures clean spectral purity critical for SERDES clock recovery |
| I²C Interface | Standard-mode (100 kHz) with 4 selectable slave addresses - allows multi-device configuration on shared bus |
| Operating Temperature | −40°C to +85°C - qualified for industrial and telecom equipment deployment |
Pinout & Package
ACS1790IMLTRT is housed in a 4 × 4 mm QFN-24 package with exposed thermal pad connected to ground. Pin functions are validated per Semtech ACS1790T datasheet Rev 1.0 (May 2013), including dedicated analog/digital/RF power and ground domains.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RESETB | Active-low asynchronous reset | Hard-resets internal state and initiates VCO calibration; must be pulled high during normal operation |
| CLK | Reference clock input | Accepts 10/12.8/20/25 MHz crystal or oscillator; determines PFD frequency via R-divider bypass/divide-by-2 logic |
| OUT1P / OUT1N | Differential LVPECL clock output | Provides high-frequency, low-jitter output; requires 50 Ω AC or DC termination per IEEE 1596 |
| OUT2 | Single-ended LVCMOS clock output | Configurable voltage (1.8/2.5/3.3 V) and slew rate; used for lower-speed system clocks or control signals |
| FBCLK | Feedback clock output | LVCMOS 3.3 V output for external PFD or ToPSync® synchronization; divided from VCO via T-divider |
| LD | Lock detect indicator | Open-drain output pulled low until PLL achieves phase lock; supports wired-OR of multiple devices |
| OEB | Output enable control | Active-low signal disabling both OUT1 and OUT2; complements register-based output gating |
| SCL / SDA | I²C interface | Standard bidirectional bus interface; requires external pull-ups; supports configuration and status readback |
Key Features
| Feature | Design Value |
|---|---|
| Integrated VCO + PFD + loop filter | Eliminates external components for PLL loop design; reduces board area and layout sensitivity |
| ±500 ppm fine-tuning range | Enables dynamic frequency adjustment post-calibration without recalibration delay or unlock risk |
| Dual independent output dividers (B & P) | Allows simultaneous generation of unrelated frequencies (e.g., 156.25 MHz + 25 MHz) from same VCO |
| Hardware-configurable default outputs | Pin-strapped reset behavior (OSCFSEL0/1, MODE) enables boot-time clock availability without I²C initialization |
| Separate VDDD2 supply for OUT2 | Permits level-shifting OUT2 to match downstream logic voltage while maintaining core PLL integrity |
Applications
| Synchronous Ethernet Line Card | 10G Base-R PHY Clocking |
|---|---|
Use Scenario: Generating transmit/receive clocks for Ethernet MAC/PHY in carrier-grade line cards requiring ITU-T G.8262 compliance. IC Role / Device Role / Timing Role: Primary clock synthesizer providing phase-aligned 156.25 MHz and 125 MHz outputs locked to Stratum 3E reference via ToPSync®. Use Value: Meets <0.56 ps RMS jitter (12 kHz–20 MHz) for OC-48/STM-16 masks and eliminates need for discrete VCO + loop filter. | Use Scenario: Delivering low-jitter reference clocks to 10GBASE-R SerDes blocks in switches/routers. IC Role / Device Role / Timing Role: Standalone synthesizer generating 155.52 MHz or 156.25 MHz with XAUI-compliant jitter (<0.11 ps). Use Value: Achieves IEEE 802.3-2008 Clause 47 mask without external jitter cleaners or reclockers. |
| SONET/SDH OC-48 Clock Module | Multi-rate Optical Transport System |
Use Scenario: Providing primary timing for OC-48 framer and mapper ICs in optical transport terminals. IC Role / Device Role / Timing Role: Dual-output synthesizer delivering 155.52 MHz (OUT1) and 77.76 MHz (OUT2) from single 12.8 MHz reference. Use Value: Supports ANSI T1.105.03 mask with 0.56 ps RMS jitter and enables pin-compatible upgrade path from legacy solutions. | Use Scenario: Flexible clock source for reconfigurable OTN muxponders supporting 2.5G/10G/40G rates. IC Role / Device Role / Timing Role: Programmable synthesizer generating 10.24 MHz (FBCLK), 125 MHz (OUT1), and 25 MHz (OUT2) simultaneously. Use Value: Enables single-chip support for multiple ITU-T G.709 frame rates via I²C reprogramming without hardware change. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PLL frequency synthesizer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMK04828BISQE/NOPB | Two-stage jitter cleaner with dual DPLLs; higher integration but no integrated VCO; requires external VCO | Targeted at ultra-low-jitter cleaning rather than direct synthesis; better for noisy reference environments | Select when reference clock has high jitter and system requires sub-50 fs RMS; not drop-in for ACS1790IMLTRT's VCO-integrated use case |
| Si5341-A01AGM | Multi-output clock generator with integrated DCO; wider output count (12) but lower max frequency (750 MHz); no LVPECL output | Optimized for datacenter clock trees with many LVDS/LVCMOS outputs; lacks telecom-specific jitter masks | Select for high-channel-count, lower-frequency systems; requires redesign for LVPECL interface and telecom jitter compliance |
Compared with LMK04828BISQE/NOPB and Si5341-A01AGM, the ACS1790IMLTRT delivers integrated VCO-based synthesis with native LVPECL output and verified compliance to Synchronous Ethernet, SONET, and XAUI jitter masks-making it optimal for space-constrained telecom timing modules where self-contained PLL functionality is essential.
Availability
ACS1790IMLTRT is available at Aetrix Electronics and suitable for Synchronous Ethernet line cards, 10G PHY clocking, SONET/SDH OC-48 modules, and multi-rate optical transport systems requiring stable component supply and long-term lifecycle support.
Supply support for ACS1790IMLTRT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Semtech Corporation is a U.S.-based semiconductor company specializing in high-performance analog and mixed-signal ICs for communications, enterprise computing, and industrial markets.
The ACS1790IMLTRT belongs to Semtech's Advanced Communications Product Group, designed specifically for precision timing in carrier-grade telecom infrastructure requiring low-jitter, I²C-programmable PLL synthesis with integrated VCO and dual-output flexibility.
FAQ
What is the function of the FBCLK pin on the ACS1790IMLTRT?
The FBCLK pin on the ACS1790IMLTRT provides a low-frequency LVCMOS feedback clock output (3.3 V fixed) derived from the VCO via the programmable T-divider. It is intended for connection to an external phase-frequency detector-such as in a ToPSync®-based Synchronous Ethernet system-to close an outer control loop. The ACS1790IMLTRT uses this signal to enable frequency locking to an external reference while maintaining local stability during holdover.
Does the ACS1790IMLTRT support 1.8 V LVCMOS output on OUT2?
Yes, the ACS1790IMLTRT supports 1.8 V LVCMOS output on OUT2 by connecting VDDD2 to 1.8 V. The device's OUT2 buffer is powered independently via VDDD2, allowing interoperability with 1.8 V logic families. This capability is confirmed in the "DC Characteristics" table (Page 22) and "OUT2 Drive-Type Setting" section (Table 8) of the ACS1790T datasheet Rev 1.0.
How does the ACS1790IMLTRT achieve 1 ppb frequency resolution?
The ACS1790IMLTRT achieves 1 ppb frequency resolution using its fractional-N feedback divider within the VCO PLL block. With a base PFD frequency of 10 or 12.8 MHz and a 2.3–2.7 GHz VCO range, the fractional divider enables sub-Hz step sizes. This resolution is explicitly specified in the Introduction (Page 1) and verified across output ranges up to 200 MHz in the "RF Characteristics" table (Page 24) of the ACS1790T datasheet.
Is the ACS1790IMLTRT pin-compatible with other Semtech synthesizers like the ACS1791?
No, the ACS1790IMLTRT is not pin-compatible with the ACS1791. While both are PLL synthesizers in Semtech's portfolio, the ACS1791 uses a different pinout (QFN-32), includes additional outputs and features (e.g., dual VCOs), and lacks identical terminal mapping. Pin compatibility is not claimed in any Semtech documentation, and the ACS1790IMLTRT's QFN-24 layout-including dedicated VDDF/VSSF and separated VDDD/VDDD2 supplies-is unique to its family.
What is the purpose of the IC pin on the ACS1790IMLTRT?
The IC pin on the ACS1790IMLTRT is an internally connected pin with no external function. As stated in Table 1 (Page 6) of the ACS1790T datasheet, it must not be connected to any trace or component. Leaving it floating or tying it to ground violates the manufacturer's recommendation and may affect RF performance or thermal behavior due to unintended coupling or parasitic paths.
ACS1790IMLTRT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Semtech Corporation
- Series:
- -
- Package/Case:
- 24-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Frequency Synthesizer (RF)
- PLL:
- Yes with Bypass
- Input:
- Clock
- Output:
- LVCMOS, LVPECL
- Number of Circuits:
- 1
- Ratio - Input:Output:
- 1:2
- Differential - Input:Output:
- No/Yes
- Frequency - Max:
- 2.7GHz
- Divider/Multiplier:
- Yes/No
- Voltage - Supply:
- 1.8V, 2.5V, 3.3V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 24-QFN (4x4)
ACS1790IMLTRT FAQ
1.How can I place an order for ACS1790IMLTRT through Aetrix?
Please submit a Request for Quotation (RFQ) for ACS1790IMLTRT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ACS1790IMLTRT reliable?
The price and inventory of ACS1790IMLTRT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ACS1790IMLTRT is usually 5 days.
3.What payment methods are accepted for ACS1790IMLTRT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ACS1790IMLTRT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ACS1790IMLTRT?
ACS1790IMLTRT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ACS1790IMLTRT order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ACS1790IMLTRT?
For technical support, including ACS1790IMLTRT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ACS1790IMLTRT requirements.
6.How does Aetrix verify that ACS1790IMLTRT is sourced from the original manufacturer or authorized distributors?
All ACS1790IMLTRT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ACS1790IMLTRT meets industry standards.
7.What is the process for return or replacement of ACS1790IMLTRT?
All ACS1790IMLTRT units undergo pre-shipment inspection (PSI). If there is an issue with ACS1790IMLTRT, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ACS1790IMLTRT part is unused and in its original packaging.
Return procedure for ACS1790IMLTRT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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