The high frequency crystal oscillator of this processor is controlled by a 32MHz external crystal and can use an optional 32.768kHz crystal for higher accuracy and lower average power consumption.
Seiko Epson offers offers both the 32MHz for the mandatory clock and the 32.768kHz for the power save clock. There are two 32MHz crystals available: FA-20H type with a 4pad 2.5x2mm package and FA-128 type with a 2×1.6mm package.
The frequency stability is ±10ppm over a temperature range of -20 to +75°C. For the 32.768kHz clock FC-135 standard type with 3.2×1.5mm and 20ppm is a good solution.