lm2599sx-5.0 National Semiconductor Corporation, lm2599sx-5.0 Datasheet - Page 12

• Manufacturer Part Number: lm2599sx-5.0
• Description: Simple Switcher Power Converter 150 Khz 3a Step-down Voltage Regulator, With Features
• Manufacturer: National Semiconductor Corporation

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LM2599 Series Buck Regulator Design Procedure (Fixed Output)
LM2599 Series Buck Regulator Design Procedure (Adjustable Output)
Given:
V
V
I
F = Switching Frequency (Fixed at a nominal 150 kHz).
1. Programming Output Voltage (Selecting R
shown in Figure 1 )
Use the following formula to select the appropriate resistor
values.
Select a value for R
resistor values minimize noise pickup in the sensitive feed-
back pin. (For the lowest temperature coefficient and the best
stability with time, use 1% metal film resistors.)
Voltage
LOAD
Output
OUT
IN
3.3
PROCEDURE (Adjustable Output Voltage Version)
(V)
12
(max) = Maximum Input Voltage
5
(max) = Maximum Load Current
= Regulated Output Voltage
Current
Conditions
Load
(A)
3
2
3
2
3
2
1
between 240
FIGURE 2. LM2599 Fixed Voltage Quick Design Component Selection Table
Max Input
Voltage
(V)
10
15
40
20
40
15
18
30
40
15
20
40
10
40
10
40
5
7
6
8
9
and 1.5 k . The lower
Inductance
(µH)
150
22
22
22
33
22
33
47
22
22
33
47
22
68
68
22
33
68
68
33
68
Inductor
1
and R
Inductor
2
L41
L41
L41
L40
L33
L32
L39
L41
L41
L40
L39
L33
L38
L38
L41
L40
L44
L44
L32
L38
L42
, as
( # )
12
HFQ Series
Panasonic
Through Hole Electrolytic
Given:
V
V
I
F = Switching Frequency (Fixed at a nominal 150 kHz).
1. Programming Output Voltage (Selecting R
shown in Figure 1 )
Select R
R
R
LOAD
470/25
560/35
680/35
560/35
470/25
330/35
330/35
470/25
560/25
330/35
330/35
470/25
180/35
180/35
470/25
330/25
180/25
180/35
330/25
180/25
OUT
IN
(µF/V)
2
2
82/25
(max) = 28V
= 1k (16.26 − 1) = 15.26k, closest 1% value is 15.4 k .
= 15.4 k .
EXAMPLE (Adjustable Output Voltage Version)
(max) = 3A
= 20V
1
to be 1 k , 1%. Solve for R
PL Series
Nichicon
560/16
560/35
680/35
470/35
470/35
330/35
270/50
560/16
560/25
330/35
270/35
560/16
180/35
180/35
470/25
330/25
180/25
180/35
330/25
180/25
(µF/V)
82/25
Output Capacitor
Surface Mount Tantalum
AVX TPS
330/6.3
330/6.3
330/6.3
330/6.3
330/6.3
330/6.3
Series
220/10
220/10
220/10
220/10
220/10
220/10
100/10
100/10
100/16
100/16
100/16
100/16
100/16
100/16
(µF/V)
68/20
2
.
(Continued)
595D Series
1
Sprague
390/6.3
390/6.3
390/6.3
390/6.3
390/6.3
390/6.3
and R
330/10
330/10
330/10
330/10
330/10
330/10
270/10
270/10
180/16
180/16
120/20
120/20
180/16
120/20
(µF/V)
68/25
2
, as