LP2989LV_15 Datasheet, PDF (17/26 Pages) Texas Instruments – Micropower and Low-Noise, 500-mA Ultra Low-Dropout Regulator for Use With Ceramic Output Capacitors

www.ti.com
LP2989LV
SNVS086K – MAY 2000 – REVISED JULY 2015
Layout Example (continued)
Example: Given an output voltage of 1.8 V, an input voltage range of 4 V to 6 V, a maximum output current of
100 mA, and a maximum ambient temperature of 50°C, what is the maximum operating junction temperature?
The maximum power dissipated by the device (P_D(MAX)) is found using the formula in Equation 2:
P_D(MAX) = ((V_IN(MAX) – V_OUT) × I_OUT(MAX)
(2)
Using Equation 2, the result is:
P_D(MAX) = ((6 V – 1.8 V) × 100 mA ) = 0.42 W
when
• I_OUT(MAX) = 100 mA
• V_IN(MAX) = 6 V
• V_OUT = 1.8 V
Using the 8-pin SOIC (D) package, the LP2989LV junction-to-ambient thermal resistance (R_θJA) has a rating of
114.5°C/W using the standard JEDEC JESD51-7 PCB (High-K) circuit board.
T_RISE = P_D(MAX) × R_θJA
(3)
Thus, The junction temperature rise above ambient (T_RISE) using the formula in Equation 3 is:
T_RISE = 0.42 W × 114.5°C/W = 48.1°C
The junction temperature rise can then be added to the maximum ambient temperature to find the estimated
operating junction temperature (T_J) using the formula in Equation 4:
T_J(MAX) = T_A(MAX) + T_RISE
(4)
which gives the following results:
T_J(MAX) = 50°C + 48.1°C = 98.1°C
Copyright © 2000–2015, Texas Instruments Incorporated
Product Folder Links: LP2989LV
Submit Documentation Feedback
17