Gehäuseinformationen
| Gehäuse | Pins TSSOP (PW) | 24 |
| Betriebstemperaturbereich (°C) -40 to 85 |
| Gehäusemenge | Träger 60 | TUBE |
Merkmale von CDCEL949
- Member of programmable clock generator family
- CDCEx913: 1 PLLs, 3 outputs
- CDCEx925: 2 PLLs, 5 outputs
- CDCEx937: 3 PLLs, 7 outputs
- CDCEx949: 4 PLLs, 9 outputs
- In-System programmability and EEPROM
- Serial programmable volatile register
- Nonvolatile EEPROM to store customer settings
- Flexible input clocking concept
- External crystal: 8MHz to 32MHz
- On-chip VCXO pull-range: ±150ppm
- Single-ended LVCMOS up to 160MHz
- Free selectable output frequency up to 230MHz
- Low-noise PLL core
- PLL loop filter components integrated
- Low period jitter: 60ps (typical)
- Separate output supply pins
- CDCE949: 3.3V and 2.5V
- CDCEL949: 1.8V
- Flexible clock driver
- Three user-definable control inputs [S0/S1/S2] (for example: SSC selection, frequency switching, output enable or power down)
- Generates highly accurate clocks for video, audio, USB, IEEE1394, RFID, Bluetooth, WLAN, Ethernet™, and GPS
- Generates common clock frequencies used with TI-DaVinci™, OMAP™, DSPs
- Programmable SSC modulation
- Enables 0ppm clock generation
- 1.8V device core supply
- Wide temperature range: –40°C to 85°C
- Packaged in TSSOP
- Development and programming kit for easy PLL design and programming (TI Pro-Clock™)
Beschreibung von CDCEL949
The CDCE949 and CDCEL949 are modular PLL-based low cost, high-performance, programmable clock synthesizers, multipliers and dividers. These devices generate up to nine output clocks from a single input frequency. Each output can be programmed in-system for any clock frequency up to 230MHz, using up to four independent configurable PLLs.
The CDCEx949 has separate output supply pins (VDDOUT): 1.8V for the CDCEL949 and 2.5V to 3.3V for the CDCE949.
The input accepts an external crystal or LVCMOS clock signal. If an external crystal is used, an on-chip load capacitor is adequate for most applications. The value of the load capacitor is programmable from 0pF to 20pF. Additionally, an on-chip VCXO is selectable, allowing synchronization of the output frequency to an external control signal, that is, a PWM signal.
The deep M/N divider ratio allows the generation of 0ppm audio or video, networking (WLAN, BlueTooth™, Ethernet, GPS) or Interface (USB, IEEE1394, Memory Stick) clocks from a reference input frequency, such as 27MHz.
All PLLs support SSC (Spread-Spectrum Clocking). SSC can be Center-Spread or Down-Spread clocking. This is a common technique to reduce electro-magnetic interference (EMI).
Based on the PLL frequency and the divider settings, the internal loop-filter components are automatically adjusted to achieve high stability, and to optimize the jitter-transfer characteristics of each PLL.
The device supports non-volatile EEPROM programming for easy customization of the device to the application. The CDCEx949 is preset to a factory-default configuration. The device can be reprogrammed to a different application configuration before PCB assembly, or reprogrammed by in-system programming. All device settings are programmable through the SDA and SCL bus, a 2-wire serial interface.
Three programmable control inputs, S0, S1 and S2, can be used to control various aspects of operation including frequency selection, changing the SSC parameters to lower EMI, PLL bypass, power down, and choosing between low level or 3-state for the output-disable function.
The CDCEx949 operates in a 1.8V environment within a temperature range of –40°C to 85°C.