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| LP38512_15 Datasheet, PDF (12/21 Pages) Texas Instruments – 1.5A Fast-Transient Response Low-Dropout Linear Voltage Regulator with Error Flag | |||
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LP38512
SNOSAU7F â NOVEMBER 2007 â REVISED APRIL 2013
~2.50V
~2.25V
VIN ~1.55V
~1.25V
VOUT
Power-Up
NOM
~90%
~85%
www.ti.com
Load
Transient
Line
Transient
Power-Down
~2.50V
VERROR
~1.25V
Figure 24. ERROR Flag Operation, biased from VIN
POWER DISSIPATION/HEATSINKING
A heatsink may be required depending on the maximum power dissipation (PD(MAX)), maximum ambient
temperature (TA(MAX)) of the application, and the thermal resistance (θJA) of the package. Under all possible
conditions, the junction temperature (TJ) must be within the range specified in the Operating Ratings. The total
power dissipation of the device is given by:
PD = ( (VINâVOUT) x IOUT) + (VIN x IGND)
where IGND is the operating ground current of the device (specified under Electrical Characteristics).
The maximum allowable junction temperature rise (ÎTJ) depends on the maximum expected ambient
temperature (TA(MAX)) of the application, and the maximum allowable junction temperature (TJ(MAX)):
ÎTJ = TJ(MAX)â TA(MAX)
The maximum allowable value for junction to ambient Thermal Resistance, θJA, can be calculated using the
formula:
θJA = ÎTJ / PD(MAX)
HEATSINKING DDPAK/TO-263 PACKAGE
The DDPAK/TO-263 and the PFM packages use the copper plane on the PCB as a heatsink. The tab, or DAP,
of these packages are soldered to the copper plane for heat sinking. Figure 25 shows a curve for the θJA of
DDPAK/TO-263 package for different copper area sizes, using a typical PCB with 1 ounce copper and no solder
mask over the copper area for heat sinking.
12
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