LP2966IMMX-3325 Datasheet, PDF (13/21 Pages) Texas Instruments – Dual 150mA Ultra Low-Dropout Regulator

LP2966
www.ti.com
SNVS028E – APRIL 2000 – REVISED APRIL 2013
Drop-Out Voltage
The drop-out voltage of a regulator is defined as the minimum input-to-output differential required to stay within
100mV of the output voltage measured with a 1V differential. The LP2966 uses an internal MOSFET with an
Rds(on) of 1Ω. For CMOS LDOs, the drop-out voltage is the product of the load current and the Rds(on) of the
internal MOSFET.
Reverse Current Path
The internal MOSFET in the LP2966 has an inherent parasitic diode. During normal operation, the input voltage
is higher than the output voltage and the parasitic diode is reverse biased. However, if the output is pulled above
the input in an application, then current flows from the output to the input as the parasitic diode gets forward
biased. The output can be pulled above the input as long as the current in the parasitic diode is limited to
150mA.
Maximum Output Current Capability
Each output in the LP2966 can deliver a current of more than 150mA over the full operating temperature range.
However, the maximum output current capability should be derated by the junction temperature. Under all
possible conditions, the junction temperature must be within the range specified under operating conditions. The
LP2966 is available in VSSOP-8 package. This package has a junction to ambient temperature coefficient (θ_ja) of
235 °C/W with minimum amount of copper area. The total power dissipation of the device is approximately given
by:
P_D = (V_in - V_OUT1)I_OUT1 + (V_in-V_OUT2)I_OUT2
(1)
The maximum power dissipation, P_Dmax, that the device can tolerate can be calculated by using the formula:
P_Dmax = (T_jmax - T_A)/θ_ja
where
• T_jmax is the maximum specified junction temperature (125°C)
• T_A is the ambient temperature
(2)
Figure 33 through Figure 37 show the variation of thermal coefficient with different layout scenarios.
Figure 33.
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