251M-33LF

251M-33LF Field Programmable SS VersaClock Synthesizer 

The 251M-33LF is a field-programmable clock synthesizer from Renesas Electronics (formerly Integrated Device Technology, IDT), belonging to the ICS251 family of VersaClock synthesizers. Housed in a compact 8-pin SOIC package with 150-mil body width, this device is designed as a low-cost, single-output clock synthesis solution that generates output frequencies ranging from 314 kHz to 200 MHz. As a factory-programmed version of the ICS251PM base device, the 251M-33LF comes pre-configured with a unique "-33" programming assigned by the factory for specific customer applications, eliminating the need for end-user programming in volume production. The device is available in tube packaging for the 251M-33LF variant and tape-and-reel packaging for the 251M-33LFT variant, supporting commercial temperature range operation from 0°C to +70°C.

Key Features and Performance Advantages

The 251M-33LF delivers several compelling features that make it a versatile timing solution. Its field programmability, enabled by the integrated OTP ROM, allows the device to be configured for a wide range of output frequencies up to 200 MHz. A key differentiator is its configurable spread spectrum modulation capability, which reduces system electromagnetic interference (EMI) by distributing energy across a frequency range rather than concentrating it at a single frequency. This feature is particularly valuable in noise-sensitive applications where EMI compliance is critical. The device can replace multiple crystals and oscillators, significantly reducing board space, component count, and overall system cost. Controllable output drive levels provide additional flexibility for interfacing with various load conditions. 

Alternative clock synthesizer ICs

● 251M-40LFT – Tape-and-reel packaged variant offering a distinct factory-programmed frequency configuration within the ICS251 family, suitable for high-volume automated assembly.

● 251MI-38LFT – Industrial temperature range (-40°C to +85°C) version of the VersaClock synthesizer with the "-38" factory configuration, providing extended operating temperature capability.

● 252M-47LF – A related frequency synthesizer from the same Renesas portfolio offering alternative PLL divider configurations and output frequency ranges for applications with different timing requirements.

● 280G-52LF – Another clock generator in Renesas' timing portfolio, providing similar PLL-based frequency synthesis functionality with different configuration options.