A new dual-PLL clock synthesiser supports applications such as PC peripheral devices, consumer electronics and embedded controller systems such as Texas Instruments’ DLP technology.
Alliance Semiconductor is sampling the ASM3P2853A, a dual-PLL clock synthesiser supporting applications such as PC peripheral devices, consumer electronics and embedded controller systems such as Texas Instruments’ DLP technology. The ASM3P2853A is a versatile spread spectrum frequency clock generator that reduces electromagnetic interference (EMI) at the clock source. This allows for significant system cost savings by reducing the number of circuit board layers and shielding that is required to pass EMI regulations.

Spread spectrum clocking technology can virtually eliminate EMI filter networks and ferrite beads, with an added benefit that circuit board traces can be routed more effectively, enhancing design flexibility and layout.

The ASM3P2853A modulates the output of the PLL in order to spread the bandwidth of the synthesised clock, thereby decreasing the peak amplitudes of its harmonics.

This results in significantly lower system EMI compared with the typical narrow band signal produced by oscillators and most clock generators.

Lowering EMI by increasing a signal’s bandwidth is called spread spectrum clock generation.

‘Spread spectrum clocking is definitely a good insurance policy’, said Nelson Arata, Product Marketing Manager for Alliance’s Analogue and Mixed Signal Business Unit.

‘Experienced designers know that EMI can be an 11th hour nightmare.

‘Spread spectrum capability will help the system designer sleep better knowing that his system has up to 6dB of additional EMI clearance’.

Packaged in an 8-pin SOIC, the ASM3P2853A provides a 50MHz spread spectrum clock and a low jitter 48MHz USB clock from a 25MHz crystal source.

Samples are available today, with initial pricing set at $1.50 in 1000-off quantities.