LT1580CT#PBF Linear Technology, LT1580CT#PBF Datasheet - Page 10

• Manufacturer Part Number: LT1580CT#PBF
• Description: IC LDO REGULATOR 7A ADJ TO220-5
• Manufacturer: Linear Technology

Specifications of LT1580CT#PBF

• Applications: Converter, Intel Pentium®
• Voltage - Input: 1.79 ~ 6 V
• Number Of Outputs: 1
• Voltage - Output: 1.25 ~ 4.65 V
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: TO-220-5 (Bent and Staggered Leads)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS
LT1580/LT1580-2.5
A protection diode between the V
pin is usually not needed. An internal diode between the
V
microsecond surge currents of 50A to 100A. Even with
large value output capacitors it is difficult to obtain those
values of surge currents in normal operation. Only with
large values of output capacitance, such as 1000 F to
5000 F, and with the V
to ground can damage occur. A crowbar circuit at the
power input can generate those levels of current, and a
diode from output to power input is then recommended.
This is shown in Figure 6. Normal power supply cycling or
system “hot plugging and unplugging” will not do any
damage.
A protection diode between the V
pin is usually not needed. An internal diode between the
V
microsecond surge currents of 1A to 10A. This can only
occur if the V
ground with a crowbar circuit with large value output
capacitors. Since the V
supply, this condition is unlikely. A protection diode from
the V
V
This is shown in Figure 6. Normal power supply cycling or
system “hot plugging and unplugging” will not do any
damage.
10
V
POWER
OUT
OUT
CONTROL
OUT
*OPTIONAL DIODES: 1N4002
pin and the V
pin and the V
Figure 6. Optional Clamp Diodes Protect Against
Input Crowbar Circuits
+
pin to the V
pin can be instantaneously shorted to ground.
+
CONTROL
V
CONTROL
POWER
POWER
U
CONTROL
CONTROL
POWER
pin is instantaneously shorted to
V
V
LT1580
CONTROL
CONTROL
INFORMATION
ADJ
U
pin on the LT1580 can handle
pin on the LT1580 can handle
pin instantaneously shorted
pin is recommended if the
pin is usually a low current
SENSE
OUT
V
OUT
OUT
W
pin and the V
pin and the V
D1*
R1
R2
D2*
+
U
CONTROL
POWER
1580 F06
V
OUT
If the LT1580 is connected as a single supply device with
the V
internal diode between the V
will protect the V
Like any other regulator exceeding the maximum input to
output differential can cause the internal transistors to
break down and none of the internal protection circuitry is
then functional.
Thermal Considerations
The LT1580 has internal current and thermal limiting
designed to protect the device under overload conditions.
For continuous normal load conditions maximum junction
temperature ratings must not be exceeded. It is important
to give careful consideration to all sources of thermal
resistance from junction to ambient. This includes junc-
tion-to-case, case-to-heat sink interface and heat sink
resistance itself. Thermal resistance specifications are
given in the electrical characteristics for both the Control
section and the Power section of the device. The thermal
resistance of the Control section is given as 0.65 C/W and
junction temperature of the Control section is allowed to
run at up to 125 C. The thermal resistance of the Power
section is given as 2.7 C/W and the junction temperature
of the Power section is allowed to run at up to 150 C. The
difference in thermal resistances between Control and
Power sections is due to thermal gradients between the
power transistor and the control circuitry.
Virtually all of the power dissipated by the device is
dissipated in the power transistor. The temperature rise in
the power transistor will be greater than the temperature
rise in the Control section so the effective thermal resis-
tance, temperature rise per watt dissipated, will be lower
in the Control section. At power levels below 12W the
temperature gradient will be less than 25 C and the
maximum ambient temperature will be determined by the
junction temperature of the Control section. This is due to
the lower maximum junction temperature in the Control
section. At power levels greater than 12W the temperature
gradient will be greater than 25 C and the maximum
ambient temperature will be determined by the Power
section. For both cases the junction temperature is deter-
mined by the total power dissipated in the device. For most
CONTROL
and V
CONTROL
POWER
input pin.
input pins shorted together the
OUT
and the V
POWER
input pin