SLVS338R May 2001 – April 2015 TPS715
The TPS715 family of LDOs consume only 3.2 µA of current while offering a wide input voltage range and low-dropout voltage in a small package. The devices, which operate over an input range of 2.5 V to 24 V, are stable with any capacitor greater than or equal to 0.47 μF. The low quiescent current makes the TPS715 ideal for powering battery management ICs. Specifically, because the TPS715 is enabled as soon as the applied voltage reaches the minimum input voltage, the output is quickly available to power continuously operating battery charging ICs.
This device has an operational input supply range of 2.5 V to 24 V, allowing for a wide range of applications. This wide supply range is ideal for applications that have either large transients or high DC voltage supplies.
This device only requires 3.2 µA (typical) of supply current from –40°C to 85°C and has a maximum current consumption of 5.8 µA at –40°C to 125°C.
Any capacitor, including both ceramic and tantalum, greater than or equal to 0.47 μF properly stabilizes this loop.
The internal current limit circuit is used to protect the LDO against high-load current faults or shorting events. The LDO is not designed to operate in a steady-state current limit. During a current limit event, the LDO sources constant current. Therefore, the output voltage falls when load impedance decreases.
if a current limit occurs and the resulting output voltage is low, excessive power is dissipated across the LDO, resulting in possible damage to the device.
The TPS715 PMOS-pass transistor has a built-in back diode that conducts current when the input voltage drops below the output voltage (for example, during power down). Current is conducted from the output to the input and is not internally limited. If extended reverse voltage operation is anticipated, external limiting may be required.
Table 1 provides a quick comparison between the normal, dropout, and disabled modes of operation.
|Normal||VIN > VOUT(nom) + VDO||IOUT < ICL|
|Dropout||VIN < VOUT(nom) + VDO||IOUT < ICL|
The device regulates to the nominal output voltage under the following conditions:
If the input voltage is lower than the nominal output voltage plus the specified dropout voltage, but all other conditions are met for normal operation, the device operates in dropout mode. In this mode, the output voltage tracks the input voltage. During this mode, the transient performance of the device becomes significantly degraded because the pass device is in the linear region and no longer controls the current through the LDO. Line or load transients in dropout can result in large output-voltage deviations.