LP38513S-1.8EV National Semiconductor, LP38513S-1.8EV Datasheet - Page 11

• Manufacturer Part Number: LP38513S-1.8EV
• Description: BOARD EVAL LP38513 1.8V
• Manufacturer: National Semiconductor

Specifications of LP38513S-1.8EV

• Channels Per Ic: 1 - Single
• Voltage - Output: 1.8V
• Current - Output: 3A
• Voltage - Input: 2.25 ~ 5.5V
• Regulator Type: Positive Fixed
• Operating Temperature: -40°C ~ 125°C
• Board Type: Fully Populated
• Utilized Ic / Part: LP38513
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

POWER DISSIPATION/HEAT-SINKING
A heat-sink may be required depending on the maximum
power dissipation (P
(T
the package. Under all possible conditions, the junction tem-
perature (T
ating Ratings. The total power dissipation of the device is
given by:
where I
(specified under Electrical Characteristics).
The maximum allowable junction temperature rise (ΔT
pends on the maximum expected ambient temperature (T
(MAX)
temperature (T
The maximum allowable value for junction to ambient Ther-
mal Resistance, θ
LP38513 is available in TO-220 and TO-263 packages. The
thermal resistance depends on amount of copper area or heat
sink, and on air flow. If the maximum allowable value of θ
calculated above is
°C/W for TO-263 package no heat-sink is needed since the
package can dissipate enough heat to satisfy these require-
ments. If the value for allowable θ
a heat sink is required.
HEAT-SINKING THE TO-220 PACKAGE
The thermal resistance of a TO-220 package can be reduced
by attaching it to a heat-sink or a copper plane on a PC board.
A(MAX)
) of the application, and the maximum allowable junction
P
)of the application, and the thermal resistance (θ
GND
D
= ( (V
J
) must be within the range specified in the Oper-
is the operating ground current of the device
J(MAX)
IN
ΔT
−V
θ
JA
J
JA
≥
, can be calculated using the formula:
OUT
):
= T
D(MAX)
= ΔT
60 °C/W for TO-220 package and
J(MAX)
) x I
), maximum ambient temperature
J
OUT
/ P
− T
D(MAX)
) + ((V
A(MAX)
JA
falls below these limits,
FIGURE 2. ERROR Flag Operation, biased from V
IN
) x I
GND
)
J
JA
) de-
≥
) of
(1)
(2)
(3)
60
JA
A
11
If a copper plane is to be used, the values of θ
same as shown in the next section for the TO263 package.
The heatsink to be used in the application should have a heat-
sink to ambient thermal resistance,
In this equation, θ
to the surface of the heat sink and θ
tance from the junction to the surface of the case. The rated
θ
θ
varies between 1.5°C/W to 2.5°C/W. If the exact value is un-
known, 2°C/W can be assumed.
HEAT-SINKING THE TO-263 PACKAGE
The TO-263 package uses the copper plane on the PCB as
a heat-sink. The tab of this package is soldered to the copper
plane for heat sinking. Figure 3 shows a curve for the θ
TO-263 package for different copper area sizes, using a typ-
ical PCB with 1 ounce copper and no solder mask over the
copper area for heat sinking.
JC
CH
is about 3°C/W for a TO220–5 package. The value for
depends on method of attachment, insulator, etc. θ
θ
HA
CH
≤
is the thermal resistance from the case
IN
θ
JA
− θ
CH
− θ
JC
JC
is the thermal resis-
JA
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will be the
20146834
JA
(4)
CH
of