SW

FB

LM5010A

VOUT

Cff

R2

L1

R1

C2

R3

FB

SW

L1

C2

R3

LM5010A

R1

R2

VOUT

C6 =

2.5V

tSS x 11.5 PA

18

LM5010A, LM5010A-Q1

SNVS376F – OCTOBER 2005 – REVISED MAY 2016

www.ti.com

Product Folder Links: LM5010A LM5010A-Q1

Submit Documentation Feedback

Copyright © 2005–2016, Texas Instruments Incorporated

8.2.2.1.9

C5

This capacitor suppresses transients and ringing due to lead inductance at VIN. TI recommends a low ESR, 0.1

µF ceramic chip capacitor, placed physically close to the LM5010Ax.

8.2.2.1.10

C6

The capacitor at the SS pin determines the soft-start time (that is the time for the reference voltage at the

regulation comparator and the output voltage) to reach their final value. Determine the capacitor value with

Equation 22.

(22)

For a 5 ms soft-start time, C6 calculates to 0.022 µF.

8.2.2.1.11

D1

A Schottky diode is recommended. Ultra-fast recovery diodes are not recommended as the high speed

transitions at the SW pin may inadvertently affect the IC’s operation through external or internal EMI. The diode

should be rated for the maximum VIN (60 V), the maximum load current (1 A), and the peak current which occurs

when current limit and maximum ripple current are reached simultaneously (IPK in Figure 9), previously calculated

to be 1.87 A. The diode’s forward voltage drop affects efficiency due to the power dissipated during the OFF-

time. The average power dissipation in D1 is calculated from Equation 23.

PD1 = VF × IO × (1 – D)

where

•

IO is the load current

•

D is the duty cycle

(23)

8.2.2.2 Low Output Ripple Configurations

For applications where low output voltage ripple is required the output can be taken directly from the low ESR

output capacitor (C2) as shown in Figure 13. However, R3 slightly degrades the load regulation. The specific

component values, and the application determine if this is suitable.

Figure 13. Low Ripple Output

Where the circuit of Figure 13 is not suitable, the circuits of Figure 14 or Figure 15 can be used.

Figure 14. Low Output Ripple Using a Feed-Forward Capacitor