LM2595DSADJR4G ON Semiconductor, LM2595DSADJR4G Datasheet - Page 10

• Manufacturer Part Number: LM2595DSADJR4G
• Description: IC REG SW 1A STEPDOWN D2PAK-5
• Manufacturer: ON Semiconductor
• Type: Step-Down (Buck)r

Specifications of LM2595DSADJR4G

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.2 ~ 37 V
• Current - Output: 1A
• Frequency - Switching: 150kHz
• Voltage - Input: 4.5 ~ 40 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: D²Pak, TO-263 (5 leads + tab)
• Output Voltage: 1.23 V to 37 V
• Output Current: 1 A
• Input Voltage: 4.75 V to 40 V
• Switching Frequency: 150 KHz
• Operating Temperature Range: - 40 C to + 125 C
• Mounting Style: SMD/SMT
• Duty Cycle (max): 95 %
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PROCEDURE (ADJUSTABLE OUTPUT VERSION: LM2595) (CONTINUED)
5. Output Capacitor Selection (C
6. Feedforward Capacitor (C
It provides additional loop stability mainly for higher input voltages.
For Cff selection use Table 1. The compensation capacitor between
0.6 nF and 15 nF is wired in parallel with the output voltage setting
resistor R2, The capacitor type can be ceramic, plastic, etc..
4. Inductor Selection (L1)
E
A. Since the LM2595 is a forward−mode switching regulator
B. The capacitors voltage rating should be at least 1.5 times
A. Use the following formula to calculate the inductor Volt x
B. Match the calculated E x T value with the corresponding
C. Next step is to identify the inductance region intersected by
D. Select an appropriate inductor from Table 3.
T + V
with voltage mode control, its open loop has 2−pole−1−zero
frequency characteristic. The loop stability is determined by
the output capacitor (capacitance, ESR) and inductance
values.
For stable operation use recommended values of the output
capacitors in Table 1.
Low ESR electrolytic capacitors between 180 mF and
1000 mF provide best results.
greater than the output voltage, and often much higher
voltage rating is needed to satisfy low ESR requirement
microsecond [V x ms] constant:
number on the vertical axis of the Inductor Value Selection
Guide shown in Figure 19. This E x T constant is a
measure of the energy handling capability of an inductor and
is dependent upon the type of core, the core area, the
number of turns, and the duty cycle.
the E x T value and the maximum load current value on the
horizontal axis shown in Figure 19.
The inductor chosen must be rated for a switching
frequency of 150 kHz and for a current rating of 1.15 x I
The inductor current rating can also be determined by
calculating the inductor peak current:
where t
IN
I
* V
p(max)
on
is the “on” time of the power switch and
OUT
+
* V
I
t on +
Load(max)
SAT
Procedure
FF
V out
)
V
V
IN
in
out
)
V
* V
OUT
x 1.0
)
V
f osc
SAT
in
) V
* V out t on
) V
D
2L
D
150 kHz
1000
http://onsemi.com
V
Load
ms
.
10
4. Inductor Selection (L1)
5. Output Capacitor Selection (C
6. Feedforward Capacitor (C
In this example, it is recommended to use a feedforward
capacitor 4.7 nF.
A. Calculate E x T [V x ms] constant:
E
E
B. E x T = 19.2 [V x ms]
C. I
D. Proper inductor value = 68 mH
A. In this example, it is recommended to use a Nichicon PM
Inductance Region = L30
Choose the inductor from Table 3.
capacitor: 220 mF/25 V
Load(max)
T + 12 * 5 * 1.0
T + 6
= 1.0 A
11.5
5.5
6.7 V
Example
12 * 1 ) 0.5
FF
5 ) 0.5
)
ms
out
)
150 kHz
1000
V
ms