Overview
The CDCM1804RGET is a high-performance clock driver produced by Texas Instruments. This component is designed to distribute one differential clock input to three LVPECL (Low-Voltage Positive Emitter-Coupled Logic) differential clock outputs and one single-ended LVCMOS (Low-Voltage Complementary Metal-Oxide-Semiconductor) output. It is specifically engineered for driving 50-Ω transmission lines, making it ideal for applications requiring precise clock distribution with minimal skew.
The CDCM1804RGET operates over a wide temperature range from -40°C to 85°C and supports signaling rates up to 800 MHz for LVPECL and 200 MHz for LVCMOS outputs. It features a programmable output divider, low-output skew, and a differential input stage with a wide common-mode range, making it versatile for various clock distribution needs.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Package | 24-Terminal QFN (RGE) | - |
| Operating Temperature Range | -40 to 85 | °C |
| Supply Voltage (VDD) | 3 to 3.6 | V |
| Input Frequency (fclk) | 0 to 800 | MHz |
| LVPECL Output Frequency | Up to 800 | MHz |
| LVCMOS Output Frequency | Up to 200 | MHz |
| Output Skew (Typical) for LVPECL | 15 ps | - |
| Output Skew Between LVCMOS and LVPECL | 1.6 ns | - |
| Input Impedance | 300 kΩ | - |
| Input Threshold | ±75 mV | - |
Key Features
- Distributes one differential clock input to three LVPECL differential clock outputs and one single-ended LVCMOS output.
- Programmable output divider for two LVPECL outputs and LVCMOS output.
- Low-output skew of 15 ps (typical) for LVPECL outputs and 1.6-ns output skew between LVCMOS and LVPECL transitions to minimize noise.
- Operates with a supply voltage range of 3 V to 3.6 V.
- Supports signaling rates up to 800 MHz for LVPECL and 200 MHz for LVCMOS outputs.
- Differential input stage with a wide common-mode range, accepting various differential signaling types (LVDS, HSTL, CML, VML, SSTL-2) and single-ended signals (LVTTL/LVCMOS).
- Provides VBB bias voltage output for single-ended input signals.
- 24-Terminal QFN package (4 mm × 4 mm).
- Three control terminals (S0, S1, S2) for selecting different output mode settings, and an enable terminal (EN) to disable or enable all outputs simultaneously.
Applications
The CDCM1804RGET is suitable for a variety of applications requiring precise clock distribution and low skew, including:
- High-speed data communication systems.
- Server and data center infrastructure.
- Add-in cards and peripheral devices.
- Telecommunication equipment.
- High-performance computing systems.
Q & A
- What is the primary function of the CDCM1804RGET?
The CDCM1804RGET distributes one differential clock input to three LVPECL differential clock outputs and one single-ended LVCMOS output.
- What is the operating temperature range of the CDCM1804RGET?
The CDCM1804RGET operates from -40°C to 85°C.
- What are the supported signaling rates for LVPECL and LVCMOS outputs?
The CDCM1804RGET supports signaling rates up to 800 MHz for LVPECL and 200 MHz for LVCMOS outputs.
- How many control terminals does the CDCM1804RGET have, and what is their purpose?
The CDCM1804RGET has three control terminals (S0, S1, S2) for selecting different output mode settings, and an enable terminal (EN) to disable or enable all outputs simultaneously.
- What types of differential signaling does the CDCM1804RGET accept?
The CDCM1804RGET accepts various differential signaling types including LVDS, HSTL, CML, VML, SSTL-2, and single-ended signals like LVTTL/LVCMOS.
- How is the output skew minimized in the CDCM1804RGET?
The CDCM1804RGET minimizes output skew with a typical skew of 15 ps for LVPECL outputs and a 1.6-ns skew between LVCMOS and LVPECL transitions.
- What is the purpose of the VBB output terminal?
The VBB output terminal provides a bias voltage for single-ended input signals, serving as a common-mode voltage reference.
- What is the recommended termination for the input signal?
For differential signals, a 100-Ω termination resistor is recommended. For optimal noise performance, using 2 × 50 Ω resistors with a center tap connected to a capacitor is suggested.
- How does the enable terminal (EN) function?
The enable terminal (EN) allows disabling or enabling all outputs simultaneously and offers three different configurations: tied to GND, external 60-kΩ pulldown resistor, or left floating.
- What is the package type and size of the CDCM1804RGET?
The CDCM1804RGET comes in a 24-Terminal QFN package with dimensions of 4 mm × 4 mm.
