Common problems and usage ideas of programmable crystal oscillators

YXC扬兴晶振

Common problems and usage ideas of programmable crystal oscillators [Copy link]

Programmable crystal oscillator. Simply put, it is a crystal oscillator with any programmable frequency, which can be enlarged or reduced by a generator to selectively achieve various bus frequencies. In actual application or preliminary understanding, various problems will be encountered. The following editor lists some common questions and answers related to SiTime programmable crystal oscillators.

What is the difference between OE and ST functions?

Most feature pins on SiTime oscillators (pin 1) can be programmed to either an "output enable" (OE) or "standby" (st) function. In both cases, pulling pin 1 low stops the output oscillation of the device, but in different ways, as described below.

Applying a logic low to the OE pin only disables the output driver and puts it in Hi-Z mode, but the rest of the device remains operational. Because the output is inactive, power consumption is reduced. For example, for a 3.3V SiT8003 20MHz device, IDD drops from 4mA to 3.3mA with a 15pF load. The output is typically on for less than 1us when the OE pin is pulled high.

Devices with an ST pin enter standby mode when the ST pin is pulled low. All internal circuits of the device are shut down and the current drops to the standby current, which is generally in the range of a few microamps. When ST is pulled high, the device will perform a "recovery" process, which may take 3ms to 10ms of standby current. The recovery time is specified in the device data sheet. Some SiTime data sheets do not specify the recovery time; in this case, the recovery time is the same as the startup time.

Q: Can I program a SiTime device to drive loads greater than 15 pF?

Yes, SiTime devices with single-ended LVCMOS outputs typically specify rise and fall times for 15pF capacitive loads. The device can drive large loads up to 60pF with slower rise and fall times. For applications that require fast rise and fall times (1ns) and the ability to drive large capacitive loads, buffer devices with high drive strength outputs are available upon request.

Q: Can I adjust the rise and fall times of a SiTime crystal output?

Yes, users can tune the output buffers of SiTime oscillators by varying the drive current strength. By increasing or decreasing the maximum drive current of the output stage, the rise and fall times can be decreased or increased, respectively. High drive current strength can drive larger loads while achieving faster rise and fall times. Low drive current strength can reduce clock edge slew rates and potential EMI.

How to use the programmable crystal oscillator! Generally, you can operate it directly according to the instructions. Precision products like this have instructions for use. As long as we can operate it reasonably according to the instructions for use of the programmable crystal oscillator, it will be fine.

Of course, for the current use of programmable crystal oscillators, you can read the instruction manual, watch video tutorials, or directly ask the programmable crystal oscillator customer service, which generally provides simple guidance services. As long as the company's operators learn how to operate it, it will be fine.

wangerxian

What products are programmable crystal oscillators generally used in?

YXC扬兴晶振

wangerxian posted on 2023-10-27 15:37 What products are programmable crystal oscillators generally used in?

The application range is relatively wide. The advantage of programmable crystal oscillator is that the frequency can be customized, accurate to the last 6 digits. It is more commonly used in general communication products and has an advantage in cost performance.

wangerxian

YXC Yangxing Crystal Oscillator published on 2023-10-27 17:01 The application range is relatively wide. The advantage of programmable crystal oscillator is that the frequency point can be customized, accurate to the last 6 digits. It is more commonly used in general communication products and has a high cost performance...

Is it possible to achieve fixed frequency directly through circuit or through program?

极限零

I feel that apart from boards with high space requirements, there is no other use for it. Generally, a board will not have more than 3 frequency requirements.

YXC扬兴晶振

wangerxian posted on 2023-10-27 17:37 Is the fixed frequency achieved directly through the circuit or through the program?

By Program

YXC扬兴晶振

Extreme Zero published on 2023-10-28 08:57 It seems that except for boards with high space requirements, there is no other use. Generally, a board will not have more than 3 frequency requirements.

The frequency of the crystal oscillator used depends on the function of the board. The more functions the board has, the more frequency types it can use.

wangerxian

YXC Yangxing Crystal Oscillator published on 2023-10-30 14:19 Through the program

Is there a demo board? I'm quite interested.

YXC扬兴晶振

wangerxian posted on 2023-10-30 16:00 Is there a demo board? I'm quite interested.

The active crystal oscillator is a complete circuit that can work as soon as it is powered on, without the need for a demo board.

wangerxian

YXC Yangxing Crystal Oscillator published on 2023-10-30 16:33 The active crystal oscillator is a complete circuit that can work when powered on, without the need for a demo board

Is there a kind of board that uses buttons or programming to control the crystal oscillator, and then there is a test point to measure the frequency of the crystal oscillator at that time.