LM2595DSADJR4G ON Semiconductor, LM2595DSADJR4G Datasheet - Page 17

• 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

3. T
4. R
5. R
(Refer to Maximum Ratings on page 2 of this data sheet or
R
total power dissipated by the LM2595:
where d is the duty cycle and for buck converter
I
V
V
I
turn−off can be neglected if proper type catch diode is used.
following expression:
where (R
caused by the dissipated power and T
ambient temperature.
Q
Load
qJC
in
O
The following formula is to calculate the approximate
The dynamic switching losses during turn−on and
The junction temperature can be determined by the
J(max)
qJC
qJA
and R
(quiescent current) and V
LM2595 data sheet,
is minimum input voltage applied,
is the regulator output voltage,
is the load current.
qJA
qJA
)(P
P
maximum allowed junction temperature
(125°C for the LM2595). For a conservative
design, the maximum junction temperature
should not exceed 110°C to assure safe
operation. For every additional +10°C
temperature rise that the junction must
withstand, the estimated operating lifetime
of the component is halved.
package thermal resistance junction−case.
package thermal resistance junction−ambient.
values).
D
D
= (V
) represents the junction temperature rise
T
J
Unregulated
in
d +
100 mF/50 V
= (R
12 to 25 V
x I
DC Input
Q
t on
qJA
T
) + d x I
) (P
C
+
in
sat
V
V in
D
) + T
can be found in the
O
Load
Figure 23. Inverting Buck−Boost Develops −12 V
,
+V
A
x V
A
in
is the maximum
sat
ON/OFF
LM2595
http://onsemi.com
GND
17
Feedback
Packages Not on a Heatsink (Free−Standing)
the junction temperature can be determined by the following
expression:
Where (R
caused by the dissipated power and T
ambient temperature.
Packages on a Heatsink
the selected safe operating junction temperature determined
in step 3, than a heatsink is required. The junction
temperature will be calculated as follows:
Where R
R
R
If the actual operating temperature is greater than the
selected safe operating junction temperature, then a larger
heatsink is required.
Some Aspects That can Influence Thermal Design
the junction temperature rise numbers are all approximate,
and there are many factors that will affect these numbers,
such as PC board size, shape, thickness, physical position,
location, board temperature, as well as whether the
surrounding air is moving or still.
area, copper thickness, single− or double−sided, multilayer
board, the amount of solder on the board or even color of the
traces.
board can also influence its effectiveness to dissipate the
heat.
qCS
qSA
D1
1N5819
For a free−standing application when no heatsink is used,
If the actual operating junction temperature is greater than
It should be noted that the package thermal resistance and
Other factors are trace width, total printed circuit copper
The size, quantity and spacing of other components on the
100 mH
L1
is the thermal resistance case−heatsink,
is the thermal resistance heatsink−ambient.
qJC
qJA
C
220 mF
T
is the thermal resistance junction−case,
out
) (P
J
= P
R3
D
) represents the junction temperature rise
D
T
J
(R
= (R
qJA
−12 V @ 0.7 A
C
R4
qJA
Regulated
+ R
FF
Output
) (P
qCS
D
+ R
) + T
qSA
A
A
) + T
is the maximum
A