DDR-SDRAM—Intel®IXP45X and Intel® IXP46X Product Line of Network Processors

Figure 42. DDR Data Read Simulation Results: Two-Bank x16 Devices (Full Drive Strength)

The simulation results in Figure 42 are for the data circuit with a DDR device using full drive strength and show that the voltage waveform meets the DDR device input voltage requirements. Vil(max) of Vref – 0.150 or 1.10 V and Vih(min) of Vref + 0.150 or 1.40 V are easily achieved at the receiver (IXP45X/IXP46X network processors). However, the receiver waveform must also not exceed a maximum voltage of Vin(max) = 2.8 V or the minimum voltage of Vin(min) = -0.3 V and the waveforms at the IXP45X/IXP46X network processors are close to these limits. A larger series resistor could be used to attenuate the signal, but the results of doing so might have an adverse effect on write operations.

Waveform results for DDR_DEVICE2 are not shown as it is not relevant when reading from DDR_DEVICE1. Due to the symmetry of the topology, waveform results when reading from DDR_DEVICE2 would be identical to those when reading from DDR_DEVICE1. When final routing data is available, simulation results for all receivers are analyzed as variations in routing may result in differences. These differences should be minimal.

 

Intel® IXP45X and Intel® IXP46X Product Line of Network Processors

February 2007

HDD

Document Number: 305261, Revision: 004

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Intel IXP45X, IXP46X manual Hdd