The U3V9Fx family of boost (step-up) voltage regulators generate higher output voltages from input voltages between 2.6 V and 20 V. They are switching regulators (also called switched-mode power supplies (SMPS) or DC-to-DC converters) and have typical efficiencies between 70% and 95%.
The regulators actively limit the instantaneous input currents to 2.2 A when boosting, and input currents up to around 900 mA can typically be maintained for many minutes without triggering thermal shutdown, though the actual performance depends on the input and output voltages as well as external factors such as ambient temperature and airflow. For boost regulators, the output current equals the input current times the efficiency divided by the boost ratio of VOUT to VIN, so the more you are boosting, the lower the maximum output current will be. The graph below shows maximum output currents that these regulators can deliver continuously at room temperature in still air and without additional heat sinking.
These regulators have several built-in protections, including cycle-by-cycle input current limiting and over-temperature shutdown. The family includes six versions with fixed output voltages ranging from 5 V to 24 V:
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Products in category “U3V9Fx Step-Up Voltage Regulators”
| Output voltage |
Typical max continuous input current* |
Min input voltage |
| 5 V |
900 mA |
2.6 V |
*Actual achievable maximum continuous current is a function of input voltage and is limited by thermal dissipation. See the output current graphs on the product pages for more information.
| Output voltage |
Typical max continuous input current* |
Min input voltage |
| 9 V |
900 mA |
2.6 V |
*Actual achievable maximum continuous current is a function of input voltage and is limited by thermal dissipation. See the output current graphs on the product pages for more information.
| Output voltage |
Typical max continuous input current* |
Min input voltage |
| 12 V |
900 mA |
2.6 V |
*Actual achievable maximum continuous current is a function of input voltage and is limited by thermal dissipation. See the output current graphs on the product pages for more information.
| Output voltage |
Typical max continuous input current* |
Min input voltage |
| 15 V |
900 mA |
2.6 V |
*Actual achievable maximum continuous current is a function of input voltage and is limited by thermal dissipation. See the output current graphs on the product pages for more information.
| Output voltage |
Typical max continuous input current* |
Min input voltage |
| 18 V |
900 mA |
2.6 V |
*Actual achievable maximum continuous current is a function of input voltage and is limited by thermal dissipation. See the output current graphs on the product pages for more information.
| Output voltage |
Typical max continuous input current* |
Min input voltage |
| 24 V |
900 mA |
2.6 V |
*Actual achievable maximum continuous current is a function of input voltage and is limited by thermal dissipation. See the output current graphs on the product pages for more information.
