TLV742P Datasheet, PDF (20/26 Pages) Texas Instruments – 200-mA, Small Size, Low-Dropout Linear Voltage Regulator

TLV742P
SBVS323 – SEPTEMBER 2017
10.2 Layout Example
VOUT
1
COUT
2
VIN
4
CIN
3
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GND PLANE
Represents via used for
application specific connections
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Figure 53. Recommended Layout Example
10.3 Thermal Considerations
Thermal protection disables the output when the junction temperature rises to approximately 160°C, allowing the
device to cool. When the junction temperature cools to approximately 140°C, the output circuitry is enables
again. Depending on power dissipation, thermal resistance, and ambient temperature, the thermal protection
circuit may cycle on and off. This cycling limits the dissipation of the regulator, which protects the regulator from
damage as a result of overheating.
Any tendency to activate the thermal protection circuit indicates excessive power dissipation or an inadequate
heat sink. For reliable operation, limit junction temperature to 125°C (maximum). To estimate the margin of safety
in a complete design (including heat sink), increase the ambient temperature until the thermal protection is
triggered; use worst-case loads and signal conditions.
For good reliability, thermal protection triggers at least 35°C above the maximum expected ambient condition of
the particular application. This configuration produces a worst-case junction temperature of 125°C at the highest
expected ambient temperature and worst-case load.
The internal protection circuitry of the LDO is designed to protect against overload conditions. This circuitry is not
intended to replace proper heat sinking. Continuously running the LDO into thermal shutdown degrades device
reliability.
10.4 Power Dissipation
The ability to remove heat from the die is different for each package type, presenting different considerations in
the printed-circuit-board (PCB) layout. The PCB area around the device that is free of other components moves
the heat from the device to the ambient air.
Performance data for JEDEC low- and high-K boards are shown in Thermal Information. Using heavier copper
increases the effectiveness in removing heat from the device. The addition of plated through-holes to heat-
dissipating layers improves heat sink effectiveness.
Power dissipation depends on input voltage and load conditions. Power dissipation (P_D) is equal to the product of
the output current and the voltage drop across the output pass element, as shown in Equation 2.
P_D = (V_IN - V_OUT) ´ I_OUT
(2)
20
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