summary

      This chip is a single-chip 32768 crystal oscillation circuit chip. The 32768 crystal and the AT32KHz chip circuit can directly output a 32768 square wave clock. The chip circuit uses an amplitude-limited oscillation circuit structure, which has the characteristics of low starting voltage, ultra-low power consumption, stable and reliable crystal starting waveform, and strong anti-interference ability. Using AT32KHz chip circuit, the 32768 quartz crystal can start vibration at about 1V operating voltage under no-load condition. The starting amplitude of the quartz crystal is about 0.4V ~ 0.6V. After integrating the 32768 clock shaping amplifier circuit inside the chip circuit, the chip can directly Output 32768 square wave clock. The drive capability of the chip's 32768 clock output is 1 ~ 5mA.

       AT32KHz crystal oscillator circuit adopts Pierce structure. The operating current of the oscillation circuit is provided by the amplitude control circuit, and the magnitude of the operating current is determined by the amplitude control circuit detecting the output amplitude of the oscillation circuit. The basic working principle of the circuit is: when the circuit is powered up, the oscillation output is zero, at this time the amplitude control circuit outputs a relatively large current, the oscillation circuit quickly starts to vibrate, the amplitude gradually increases, and the amplitude control circuit then reduces the output current; when the amplitude When the set value is reached, the output current of the amplitude control circuit is no longer reduced, the circuit is maintained in this state, and the output amplitude remains unchanged. The operating current is used to control the amplitude. On the one hand, the operating point of the circuit is relatively stable; on the other hand, after the amplitude is limited, the effect of non-linear effects is reduced, so the frequency stability is improved. At the same time, the stability of the operating point also makes the working current change less with voltage, which effectively reduces power consumption. In addition, using the amplitude-to-current feedback mechanism, the circuit can automatically adjust the operating point based on changes in crystals and process parameters.

Pin configuration

AT32KHz-SOT23-6 (version A)                AT32KHz-SOT23-5 (version B)

引脚功能

Note: Be sure to connect a bypass capacitor of 0.1μF or more between V_DD and V_SS.

Typical application circuit