Wide Supply Range 32 kHz Oscillator

To generate a system clock or auxiliary sleep clock in microcontrollers (µCs) and low-power instruments we usually use A 32kHz oscillator. A CMOS inverter (74HC04 or CD4049UB type) biased as a linear amplifier by connecting a large-valued resistor from the input to the output is one of usual implementation.

The inverter circuits give us problems.  To attain Supply currents fluctuate widely over a 3V to 6V supply range, and currents below 250µA is difficult. For wide variations in supply voltage,the operation can be unreliable. Further, the inverter’s input characteristics can vary widely and they are not guaranteed. To solves this problems we can use A very low-power crystal oscillator.  this oscillators only  uses 13µA from a 3V supply,  it is comprise with a low-power comparator/reference device (IC1) and a single-transistor amplifier/oscillator (Q1). Q1’s base is biased at 1.25V via R4, R5,  and the reference in IC1. VBE is about 0.7V, placing the emitter at approximately 0.5V. The amplifier’s nominal gain (R1/R2) is approximately 2V/V.

oscillator 32khz circuit schematic diagram

This circuit starts quicker and more reliable at any supply voltage than inverter-based oscillators. This circuit is made from components with a value that is not critical.  We can replace Q1 with any small-signal transistor which has  decent beta of 100 or so at 5µA. The maximum supply currents that is allowed for IC1 is nearly flat over the 2.5V to 11V supply range.

This entry was posted in Oscillators and tagged . Bookmark the permalink.,
Possibly Related to "Wide Supply Range 32 kHz Oscillator" Circuits

  • Wide Input-Voltage Range High-Power LED Driver
    This is a wide input-voltage range high-power LED driver circuit. This circuit based on a buck/boost converter controller regulates current to a white LED. This circuit can be used to replace incandescent bulbs, it efficiently match the LEDs to available … Continue reading →...
  • PLL Oscillator for Medium Wave Frequency
    What is a PLL oscillator? PLL stands for phase locked loop, and this means a control method by comparation of the controlled plant or system to a reference clock or oscillator, that the plant is controlled to synchronize the clock. … Continue reading →...
  • Sine Wave Oscillator
    This is a Sine Wave Oscillator circuit. This circuit as known as  amplitude-stabilized sine-wave oscillator. It can gives high purity sine-wave output down to low frequencies with minimum circuit complexity. This circuit has a several advantages such as it does … Continue reading →...
  • Basic Phase Shift Oscillator 1KHz
    Phase shift oscillators uses capacitors to shift the phase of a signal coming from the output of an amplifier. If the phase shifting match the frequency, then a positive feedback will be produced a continuous sine waveform. Here is the … Continue reading →...
  • Small Discrete Audio Power Amplifier
    This is a little audio amplifier, it is similar to the audio amplifier which is used in small transistor radio. This circuit draws about 30 milliamps from a 9 volt supply. This circuit consist of two stage. First stage is … Continue reading →...

Comments are closed.