AD7740 CLKIN drived by 32.768kHz external clock.
When I used cylinder type crystal with 12.5pF Load capacitor ，AD7740 can work.
When I used surface mount type crystal with 12.5pF Load capacitor,AD7740 can not work.
In datasheet page.8, I get the infomation about 32kHz watch crystal needed external circuitry.
MY question is the 32khz watch crystal means 32.768kHz crystal ?
And when I used cylinder type crystal with 12.5pF Load capacitor , AD7740 always can work without the external circuitry.