LP38853EVAL National Semiconductor, LP38853EVAL Datasheet - Page 2

• Manufacturer Part Number: LP38853EVAL
• Description: BOARD EVALUATION LP38853
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LP38853EVAL

• Channels Per Ic: 1 - Single
• Voltage - Output: 1.2V
• Current - Output: 3A
• Voltage - Input: 3 ~ 5.5V
• Regulator Type: Positive Adjustable
• Operating Temperature: -40°C ~ 125°C
• Board Type: Fully Populated
• Utilized Ic / Part: LP38853
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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The Enable pin has a 200 kΩ internal resistor to V
Enable pin is left open, care should be taken to minimize any
capacitance on the Enable pin, as any capacitance will intro-
duce an RC delay time on the Enable function.
Soft-Start Function
V
of the SS pin (r
to the SS pin. This allows the output voltage to rise in a con-
trolled manner until steady-state regulation is achieved. Typ-
ically, five time constants are recommended to assure that the
output voltage is sufficiently close to the final steady-state
value. During the soft-start time the output current can rise to
the built-in current limit.
The LP38853S-ADJ Evaluation board is assembled with a
0.01 μF capacitor for C
proximately 750 μs.
REF
will rise at an RC rate defined by the internal resistance
FIGURE 3. Enable Thresholds
SS
), and the external capacitor (C
FIGURE 4. V
SS
. This sets the soft-start time to ap-
OUT
Soft-Start
SS
20199205
20199204
) connected
BIAS
. If the
2
Power Dissipation
The TO-263 package alone has a junction to ambient thermal
resistance (θ
LP38853S evaluation board the θ
40°C/W.
Although there is only approximately 0.30 square inches of 1
ounce copper area immediately under the tab, the top copper
surface area is extended to additional copper area on the
bottom of the board by nine thermal vias.
With the 40°C/W thermal rating the LP38853S-ADJ evalua-
tion board will dissipate a maximum of 2.5W with T
FIGURE 5. Maximum Power Dissipation vs Ambient
JA
) rating of 60°C/W. When mounted on the
Temperature
JA
rating is approximately
20199206
A
= 25°C.