AN937 Datasheet, PDF (20/29 Pages) STMicroelectronics – The L4971 is a 1.5 A monolithic dc-dc converter

Typical application
AN937
Figure 24. Ideal inductor value requested for 30% ripple current, as a function of
max. input voltage and output (f_SW=150 kHz)
180
162
144
126
108
90
72
54
36
18
0
0
5
10
15
20
25
30
35
40
45
Vout
Vin = 15V
Vin = 20V
Vin = 25V
Vin = 30V
Vin = 35V
Vin = 40V
Vin = 45V
Figure 25. Ideal inductor value requested for 30% ripple current, as a function of
max. input voltage and output (f_SW=200 kHz)
140
126
112
98
84
70
56
42
28
14
0
0
5
10
15
20
25
30
35
40
45
Vin
Vin = 15V
The 120 µH value of the selected inductor is useful to keep the current ripple below
0.3*I_LOAD over the input / output voltage range operating at 200 kHz.
20/29
Doc ID 5655 Rev 15