The oscillator frequency for the SG3525 PWM controller is determined by the timing resistor (RT), the timing capacitor (CT), and the discharge resistor (RD). The formula used to calculate the frequency is:
\[ f = \frac{1.0}{CT (0.7 \cdot RT + 3 \cdot RD)} \]
Let's assume the following values:
Step 1: Convert CT from microfarads to farads:
\[ CT = 0.01 \, \mu F = 0.01 \times 10^{-6} \, F = 0.00000001 \, F \]
Step 2: Calculate the weighted sum of RT and RD:
\[ 0.7 \cdot RT + 3 \cdot RD = 0.7 \cdot 10000 + 3 \cdot 5000 = 7000 + 15000 = 22000 \, \text{Ω} \]
Step 3: Calculate the product with CT:
\[ CT \times (0.7 \cdot RT + 3 \cdot RD) = 0.00000001 \times 22000 = 0.00022 \]
Step 4: Calculate the frequency:
\[ f = \frac{1.0}{0.00022} = 4545.45 \, \text{Hz} \]
Therefore, the calculated frequency is approximately 4545.45 Hz.
