LP2953IN-3.3 National Semiconductor, LP2953IN-3.3 Datasheet - Page 12

• Manufacturer Part Number: LP2953IN-3.3
• Description: IC REG LDO 3.3V 250MA 16-DIP
• Manufacturer: National Semiconductor

Specifications of LP2953IN-3.3

• Regulator Topology: Positive Fixed
• Voltage - Output: 3.3V
• Voltage - Input: Up to 30V
• Voltage - Dropout (typical): 0.47V @ 250mA
• Number Of Regulators: 1
• Current - Output: 250mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: 16-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Other names: *LP2953IN-3.3

www.national.com
Schematic Diagram
Application Hints
HEATSINK REQUIREMENTS (Industrial Temperature
Range Devices)
The maximum allowable power dissipation for the LP2952/
LP2953 is limited by the maximum junction temperature
(+125˚C) and the external factors that determine how quickly
heat flows away from the part: the ambient temperature and
the junction-to-ambient thermal resistance for the specific
application.
The industrial temperature range (−40˚C ≤ T
parts are manufactured in plastic DIP and surface mount
packages which contain a copper lead frame that allows
heat to be effectively conducted away from the die, through
J
≤ +125˚C)
12
the ground pins of the IC, and into the copper of the PC
board. Details on heatsinking using PC board copper are
covered later.
To determine if a heatsink is required, the maximum power
dissipated by the regulator, P(max), must be calculated. It is
important to remember that if the regulator is powered from
a transformer connected to the AC line, the maximum
specified AC input voltage must be used (since this pro-
duces the maximum DC input voltage to the regulator).
Figure 1 shows the voltages and currents which are present
in the circuit. The formula for calculating the power dissi-
pated in the regulator is also shown in Figure 1:
01112706