Hyungsung, 1) Unfortunately I cannot verify the waveforms. These are old devices from National Semiconductor, and we no longer have the evaluation boards for me to check on my lab bench. 2) Sometimes devices with multiple supplies do not operate correctly if the power supplies experience some issue at power-up (transient, ramping out of order, etc.). If you try asserting the RESETn pin, this should clear any issues, power-up or otherwise, from the device. Have you had better success with the RESETn pin?
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