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Clock Divider Calculator
Calculate the nearest integer clock divider, actual output frequency, period, and frequency error for MCU timers, SPI clocks, FPGA clock enables, and digital timing designs.
Input Parameters
Results
Equations Used
Ideal Divider = Input Clock / Target Frequency
Actual Frequency = Input Clock / Selected Divider
Error % = (Actual - Target) / Target × 100%
Period = 1 / Actual Frequency
Frequently Asked Questions (FAQ)
Q1: What is a clock divider?
A clock divider reduces an input clock by an integer ratio to create a lower output frequency.
Q2: Why is there frequency error?
If the ideal divider is not an allowed integer, the closest divider produces a slightly different frequency.
Q3: When should I use power-of-two divider mode?
Use it for hardware that only supports binary prescalers such as ÷2, ÷4, ÷8, or ÷16.
Q4: Is this useful for SPI clock setup?
Yes. It helps estimate actual SPI clock from MCU peripheral clock and prescaler limits.
Q5: What error is acceptable?
It depends on the interface. UART is stricter than many timer/PWM applications.
Q6: Does this generate a phase-locked clock?
No. It only models integer division and does not include PLL jitter or duty-cycle correction.
