Pin Configurable/Selectable Oscillators
1. What are Pin Configurable/Selectable Oscillators?
Configurable selectable oscillators are oscillators that can be configured to a specific output frequency. They are available in both analog and digital forms and can be programmed to output a specific frequency or frequency range.
The frequency can be adjusted by replacing components within the oscillator or by using a frequency selection circuit. Configurable selectable oscillators typically have frequencies ranging from a few kHz to several GHz. These oscillators can be used in a variety of applications such as frequency control, clock generation, timing, and synchronization.
2. How do Pin Configurable/Selectable Oscillators Work?
The pins on the oscillator can be set to adjust the frequency, stability, and other characteristics of the oscillator. By adjusting the pins on the oscillator, different frequencies, output levels, and stability can be achieved depending on the application requirements.
3. What are Pin Configurable/Selectable Oscillators Used for?
Multi-protocol Interface Clock Source
Dynamic clock adaptation of interfaces such as USB 2.0/3.0, PCIe Gen1-Gen4, etc.
FPGA/CPLD Configuration System
Boot mode selection through dedicated configuration pins (such as Bank14/Bank15)
Low-power Devices
Switch to a 32.768KHz low-frequency clock through pin control in sleep mode
Pin Configurable/Selectable Oscillators FAQs
1. How to configure the oscillator through pins?
Level Selection: Select the preset frequency by pulling up/down the specified pin (such as CLK_SEL0, CLK_SEL1).
Combinational Logic: Multiple pins form binary encoding to support more frequency options (for example, 2 pins can provide 4 combinations).
Note: Refer to the data sheet to confirm the pin level requirements (such as TTL/CMOS voltage).
2. What frequency options do pin configurable/selectable oscillators support?
The supported frequency range and options vary by device. Common configurations include:
Basic Mode: low speed (32.768 kHz) for low power consumption, high speed (8 MHz~100 MHz) for main clock.
Extended Mode: Some devices support fractional division or multiplication (such as PLL bypass mode).
Key Parameters: frequency tolerance (±0.5%~±5%), temperature stability (±10 ppm~±100 ppm).
3. What should be paid attention to when switching the frequency of the pin configurable/selectable oscillator?
Voltage Stability: Ensure that there is no fluctuation in the power supply during switching to avoid an accidental reset.
Timing constraints: Some devices require pin configuration after reset, or wait for the clock to stabilize before switching.
Transient Interference: High-speed switching may cause EMI. It is recommended to add filter capacitors or series resistors.
4. What are the typical application scenarios of a pin configurable/selectable oscillator?
Dynamic Power Management: Switch to low-speed mode to reduce power consumption (such as battery-powered devices).
Multi-protocol Compatibility: Adapt different clock rates for interfaces such as UART and SPI.
Fault Recovery: Switch to backup oscillator when the main clock fails.
5. How to reduce electromagnetic interference (EMI) of pin configurable/selectable oscillators?
Layout Optimization: Shorten clock pin routing and keep away from analog signal paths.
Shielding Measures: Surround clock lines with ground wires or use shielded cables.
Slope Control: Enable oscillator slew rate limiting function (if any).
6. Does the pin configurable/selectable oscillator support dynamic switching during runtime?
Some Devices Support: Make sure that no critical tasks are running during the switching process (such as Flash writing).
Sequential Operation: Switch to intermediate frequency (such as PLL bypass) first, then switch to target frequency.
Asynchronous System Risk: It may cause peripheral (ADC, timer) timing errors and needs to be reinitialized.