LP38502-ADJ Datasheet, PDF (16/27 Pages) Texas Instruments – LP3850x-ADJ, LP3850xA-ADJ 1.5-A Flexcap Low-Dropout Linear Regulatorfor 2.7-V to 5.5-V Inputs

LP38500-ADJ, LP38502-ADJ
SNVS539G – NOVEMBER 2007 – REVISED JUNE 2015
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9 Power Supply Recommendations
The LP38500-ADJ and LP38502-ADJ devices are designed to operate from an input voltage supply range
between 2.7 V and 5.5 V. The input voltage range provides adequate headroom in order for the device to have a
regulated output. This input supply must be well regulated. An input capacitor of at least 10 μF is required.
9.1 Power Dissipation/Heatsinking
The maximum power dissipation (P_D(MAX)) of the LP38500-ADJ and LP38502-ADJ is limited by the maximum
junction temperature of 125°C, along with the maximum ambient temperature (T_A(MAX)) of the application, and the
thermal resistance (R_θJA) of the package. Under all possible conditions, the junction temperature (T_J) must be
within the range specified in the Recommended Operating Conditions. The total power dissipation of the device
is given by:
P_D = ((V_IN − V_OUT) × I_OUT) + (V_IN × I_GND)
where
• I_GND is the operating ground current of the device (specified under Electrical Characteristics)
(3)
The maximum allowable junction temperature rise (ΔT_J) depends on the maximum expected ambient
temperature (T_A(MAX)) of the application, and the maximum allowable junction temperature (T_J(MAX)):
ΔT_J = T_J(MAX)− T_A(MAX)
(4)
The maximum allowable value for junction-to-ambient thermal resistance, R_θJA, can be calculated using the
formula:
R_θJA = ΔT_J / P_D(MAX)
(5)
The LP38500-ADJ and LP38502-ADJ are available in the DDPAK/TO-263, TO-263, and WSON packages. The
thermal resistance depends on the amount of copper area allocated to heat transfer.
16
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