SNVU283B August   2013  – December 2021 LMZ31520 , LMZ31530

 

  1.   Trademarks
  2. 1Description
  3. 2Getting Started
  4. 3Test Point Descriptions
  5. 4Operation Notes
  6. 5Performance Data
  7. 6Schematic
  8. 7Bill of Materials
  9. 8PCB Layout
  10. 9Revision History

4 Operation Notes

In order to operate the EVM using a single power supply, the VIN Select jumper (J4) must be in the default PVIN-VIN position shown in Figure 2-1. In this position, the PVIN and VIN pins of the device are connected together. The UVLO threshold of the EVM is approximately 4.2 V with 0.25 V of hysteresis. The input voltage must be above the UVLO threshold to start up the device. After start-up, the minimum input voltage to the device must be at least 4.5 V or (VOUT + 1.0 V), whichever is greater. The maximum operating input voltage for the device is 15 V. Refer to the product data sheet for further information on the input voltage range, and optional split power supply operation for operating with PVIN as low as 3.0 V when using an external Vbias supply.

After application of the proper input voltage, the output voltage of the device will ramp to its final value in approximately 0.7 ms. If desired, this soft-start time can be increased by increasing the value of the Rss resistor (R6). Refer to the LMZ31520 20-A Power Module With 3-V to 14.5-V Input Data Sheet and LMZ31530 30-A Power Module With 3-V to 14.5-V Input Data Sheet for further information on adjusting the soft-start time.

The EVM includes input and output capacitors to accommodate the entire range of input and output voltage conditions. The actual capacitance required will depend on the input and output voltage conditions of the particular application, along with the desired transient response. In most cases, the required output capacitance will be less than that supplied on the EVM. Refer to the LMZ31520 20-A Power Module With 3-V to 14.5-V Input Data Sheet and LMZ31530 30-A Power Module With 3-V to 14.5-V Input Data Sheet for further information on the minimum required I/O capacitance and transient response.

The LMZ315x0 can be operated in either auto-skip Eco-Mode or in forced continuous conduction mode (FCCM) by selecting the desired mode using J1. Refer to the LMZ31520 20-A Power Module With 3-V to 14.5-V Input Data Sheet and LMZ31530 30-A Power Module With 3-V to 14.5-V Input Data Sheet for further information on selecting the mode of operation.