LM5117PMH/NOPB National Semiconductor, LM5117PMH/NOPB Datasheet - Page 20

• Manufacturer Part Number: LM5117PMH/NOPB
• Description: IC BUCK CONTROLLER 20-TSSOP
• Manufacturer: National Semiconductor
• Series: -r

Specifications of LM5117PMH/NOPB

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 530kHz
• Duty Cycle: 95%
• Voltage - Supply: 5.5 V ~ 65 V
• Buck: Yes
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

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The LM5117 has an exposed thermal pad to aid power dissi-
pation. Adding several vias under the exposed pad helps
conduct heat away from the IC. The junction to ambient ther-
mal resistance varies with application. The most significant
variables are the area of copper in the PC board, the number
of vias under the exposed pad and the amount of forced air
20
cooling. The integrity of the solder connection from the IC ex-
posed pad to the PC board is critical. Excessive voids greatly
decrease the thermal dissipation capacity.
The highest power dissipating components are the two power
switches. Selecting NMOS switches with exposed pads aids
the power dissipation of these devices.