Item

Description

Value

C1

Ceramic Capacitor

(2) 2.2 µF, 100V

C2

Ceramic Capacitor

22 µF, 16V

C3

Ceramic Capacitor

0.47 µF, 16V

C4, C6

Ceramic Capacitor

0.022 µF, 16V

C5

Ceramic Capacitor

0.1 µF, 100V

D1

Schottky Diode

100V, 6A

L1

Inductor

100 µH

R1

Resistor

1.0 k

Ω

R2

Resistor

1.0 k

Ω

R3

Resistor

1.5

Ω

R

ON

Resistor

200 k

Ω

U1

National Semi LM5010A

MINIMUM LOAD CURRENT

The LM5010A requires a minimum load current of 500 µA. If

the load current falls below that level, the bootstrap capacitor

(C4) may discharge during the long off-time, and the circuit

will either shutdown, or cycle on and off at a low frequency.

If the load current is expected to drop below 500 µA in the

application, R1 and R2 should be chosen low enough in

value so they provide the minimum required current at nomi-

nal V

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 9. However, R3 slightly

degrades the load regulation. The specific component val-

ues, and the application determine if this is suitable.

Where the circuit of Figure 9 is not suitable, the circuits of

Figure 10 or Figure 11 can be used.

20153835

FIGURE 7. Efficiency vs Load Current and V

IN

Circuit of Figure 6

20153837

FIGURE 8. Frequency vs V

IN

Circuit of Figure 6

20153815

FIGURE 9. Low Ripple Output

20153848

FIGURE 10. Low Output Ripple Using a Feedforward

Capacitor

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