【Product Application】Selection indicators of Three-terminal Voltage Regulator 78L33

Voltage

Input voltage (withstand voltage): it refers to the voltage range of 78L33 Vin. If the input voltage is higher than the maximum working voltage of 78L33, it will exceed the voltage withstand degree and damage. If the input voltage is lower than the minimum working voltage of 78L33, then 78L33 will not work properly.

Output voltage: refers to the voltage value of 78L33 Vout, commonly used to power MCU, common voltage values are 3.3V, 5.0V, but also has its special application of adjustable voltage value; In addition, the Accuracy of the output voltage should be considered, which means the error value of the 78L33 output voltage.

Current

Output current (Iout) : refers to the maximum output current that 78L33 can provide, to ensure that the supply current on the application, if it exceeds its withstand current value, it will not only cause instability of the output voltage value reduction, but also may have the problem of too much power.

Quiescent current (IQ) : refers to the power consumption of the 78L33’s internal circuits. The quiescent current (IQ) flows from the GND pin and should be as small as possible in low-power applications to reduce power consumption. The quiescent current is proportional to the input voltage and the output current, taking into account the maximum input voltage and output current. The following diagram shows the relationship between the quiescent current and the input voltage.

Line adjustment

Line Regulation: refers to the 78L33 with the input voltage changes, the amount of the output voltage change. When the output voltage can be stably maintained at 3.3V (the input voltage needs to be greater than the output voltage 2V), the line adjustment rate change test conditions Vin=7V~18V, Iout=20mA, and its specifications are between -150mV ~150mV.

Load Regulation: refers to the 78L33 load change or output current change, the output voltage change. When the input voltage is 10V, the output current is from 1mA to 100mA, and the output voltage change is between -100mV and 100mV.

Load Transient Response: Indicates the maximum change in output voltage caused by sudden change of load current or input voltage. Take 78L33 as an example:

Load variation: Rated input voltage (within withstand voltage range) Load from 10mA to 50mA to 10mA, 10mA to 100mA to 10mA.