TPS7B6933 Datasheet, PDF (12/21 Pages) Texas Instruments – 150-mA, 40-V Ultralow-Quiescent-Current LDO

TPS7B6933, TPS7B6950
SLVSDI2 – APRIL 2016
www.ti.com
8.2.2.1 Input Capacitor
The device requires an input decoupling capacitor, the value of which depends on the application. The typical
recommend value for the decoupling capacitor is higher than 0.1 µF. The voltage rating must be greater than the
maximum input voltage.
8.2.2.2 Output Capacitor
The device requires an output capacitor to stabilize the output voltage. The output capacitor value should be
between 2.2 µF and 100 µF. The ESR value range should be between 1 mΩ and 2 Ω. TI recommends a ceramic
capacitor with low ESR to improve the load-transient response.
8.2.2.3 Power Dissipation and Thermal Considerations
Use Equation 1 to calculate the power dissipated in the device.
P_D = I_O ´ (V_I - V_O ) + I_Q ´ V_I
where
• P_D = continuous power dissipation
• I_O = output current
• V_I = input voltage
• V_O = output voltage
(1)
Because I_Q « I_O, the term I_Q × V_I in Equation 1 can be ignored.
For a device under operation at a given ambient air temperature (T_A), use Equation 2 to calculate the junction
temperature (T_J).
T_J = T_A + (Z _qJA ´ P _D )
where
Z_θJA = junction-to-ambient air thermal impedance
(2)
Use Equation 3 to calculate the rise in junction temperature because of power dissipation.
DT = T_J - T_A = (Z _qJA ´ P_D )
(3)
For a given maximum junction temperature (T_Jmax), use Equation 4 to calculate the maximum ambient air
temperature (T_Amax) at which the device can operate.
T_{A max} = T_Jmax - (Z _qJA ´ P_D )
(4)
8.2.3 Application Curve
V_I
5 V/div
V_O
2 V/div
C_O = 2.2 µF, 400 µs/div
Figure 20. Power Up (5 V)
12
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