LM2991SSLASHNOPB datasheet(6/19 Pages) TI1

6 / 19 page

LM2991

SNVS099H – MAY 1999 – REVISED JUNE 2013

www.ti.com

TYPICAL PERFORMANCE CHARACTERISTICS (continued)

Adjust Pin Current

Low Voltage Behavior

Figure 15.

Figure 16.

Maximum Power

Maximum Power Dissipation

Dissipation (TO-220)

(DDPAK/TO-263)(1)

Figure 17.

Figure 18.

(1)

The maximum allowable power dissipation is a function of the maximum operating junction temperature (TJ(MAX)), the thermal resistance

of the package (

θJA), and the ambient temperature (TA). The maximum allowable power dissipation is: PD = (TJ(MAX) − TA)/θJA, where

TJ(MAX) is 125°C, and TA is the maximum expected ambient temperature. If this dissipation is exceeded, the die temperature will rise

above 125°C. Excessive power dissipation will cause the LM2991 to go into thermal shutdown (See Thermal Shutdown). For the

LM2991, the junction-to-ambient thermal resistance is 53°C/W for the TO-220, 73°C/W for the DDPAK/TO-263, and junction-to-case

thermal resistance is 3°C/W. If the DDPAK/TO-263 package is used, the thermal resistance can be reduced by increasing the PC board

copper area thermally connected to the package. Using 0.5 square inches of copper area,

θJA is 50°C/W; with 1 square inch of copper

area,

θJA is 37°C/W; and with 1.6 or more square inches of copper area, θJA is 32°C/W.

Submit Documentation Feedback

Product Folder Links: LM2991

LM2991S/NOPB Datasheet(PDF) 6 Page - Texas Instruments