SLVSHR7 Data sheet

SLVSHR7 August 2024 TPSM8287A12M , TPSM8287A15M

PRODUCTION DATA

9.3.2.5 Selecting the Compensation Capacitor, C_Comp1

First, use Equation 54 to calculate the bandwidth of the inner loop:

Equation 54.

{B W}_{I N N E R} = \frac{τ}{2 π \times \frac{L}{Nɸ} \times C_{O U T}}

Equation 55.

{B W}_{I N N E R} = \frac{12.5 \times 10^{- 6}}{2 π \times \frac{100 \times 10^{- 9}}{4} \times 1041 \times 10^{- 6}} = 76.4 k H z

Next, calculate the product of g_mR_Comp1:

Equation 56.

g_{m} \times R_{Comp1} = 1.5 \times 10^{- 3} \times 2000 = 3.0

If g_mR_Comp1 > than 1, use Equation 57 to calculate the recommended value of C_Comp1, which sets a zero in the control loop. If g_mR_Comp1 < 1, use Equation 59 to calculate the recommended value of C_Comp1.

Equation 57.

C_{Comp1} = \frac{2}{π \times {B W}_{I N N E R} \times g_{m} \times {R_{Comp1}}^{2}}

Equation 58.

C_{Comp1} = \frac{2}{π \times 76.4 \times 10^{3} \times 1.5 \times 10^{- 3} \times {(2000)}^{2}} = 1.39 n F

The closest standard value is 1.5nF.

Equation 59.

C_{Comp1} = \frac{2 \times g_{m}}{π \times {B W}_{I N N E R}}

Equation 60 approximates the loop bandwidth.

Equation 60.

B W = {B W}_{INNER} \times 2 \times (1 + R_{C o m p 1} \times g_{m})

Equation 61.

B W = 76.4 \times 10^{3} \times 2 \times (1 + 2000 \times 1.5 \times 10^{- 3}) = 612 k H z

9.3.2.5 Selecting the Compensation Capacitor, CComp1

9.3.2.5 Selecting the Compensation Capacitor, C_Comp1