LM2595DSADJR4G ON Semiconductor, LM2595DSADJR4G Datasheet - Page 19

• 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

5.0 V
pin requires some level shifting techniques. This is caused
by the fact, that the ground pin of the converter IC is no
longer at ground. Now, the ON/OFF pin threshold voltage
(1.3 V approximately) has to be related to the negative
output voltage level. There are many different possible shut
down methods, two of them are shown in Figures 25 and 26.
Design Recommendations:
buck−boost converter can be applied. The output capacitor
C
standard buck converter. Low input voltages or high output
currents require a large value output capacitor (in the range
of thousands of mF). The recommended range of inductor
Figure 25. Inverting Buck−Boost Regulator Shutdown
out
With the inverting configuration, the use of the ON/OFF
The same design rules as for the previous inverting
0
must be chosen larger than would be required for a what
NOTE: This picture does not show the complete circuit.
Off
On
Shutdown
Input
+V
Circuit Using an Optocoupler
in
470
R3
Unregulated
DC Input
100 mF/
−12 V
C
100 mF
50 V
in
C
in
MOC8101
47 k
R1
+V
in
7
5
Figure 27. Negative Boost Regulator
+V
ON/OFF
R2
47 k
LM2595
in
100 mH
L1
6
http://onsemi.com
ON/OFF
LM2595
GN
D
-V
out
19
GND
Negative Boost Regulator
and it is called negative boost regulator. This regulator
experiences relatively high switch current, especially at low
input voltages. The internal switch current limiting results in
lower output load current capability.
configuration. The input voltage in this application ranges
from −5.0 V to −12 V and provides a regulated −12 V output.
If the input voltage is greater than −12 V, the output will rise
above −12 V accordingly, but will not damage the regulator.
values for the negative boost regulator is the same as for
inverting converter design.
converters cannot provide current limiting load protection in
the event of a short in the output so some other means, such
as a fuse, may be necessary to provide the load protection.
Figure 26. Inverting Buck−Boost Regulator Shutdown
This example is a variation of the buck−boost topology
The circuit in Figure 27 shows the negative boost
Another important point is that these negative boost
NOTE: This picture does not show the complete circuit.
Feedback
+V
in
+V
0
1N5822
Circuit Using a PNP Transistor
On
D1
C
100 mF
in
Off
5.6 k
R2
Q1
2N3906
Shutdown
Input
R4
R3
+V
7
in
5
C
470 mF
out
ON/OFF
R1
12 k
LM2595
−12 V @ 0.25 A
Regulated
6
Output
GN
D
-V
out