Within the EFP01 family, only EFP0108, EFP0109, EFP0110, EFP0111 can be used as a Boost converter for an application that has source voltage less than the desired load voltage. Out of all available OPNs, there are only two development boards – BRD8100A [EFP0108] and BRD8100B [EFP0111] currently available that can be used to develop such an application.

If the user wants to develop an application for EFP0109 but is interested to test his proof of concept before prototyping, the user can use BRD8100A to approximate EFP0109 along with the hardware and software modifications explained in Case 2 of this KBA.

Case 1 [0.8V < Vin < 1.8V]

For source voltage less than 1.8V, BRD8100A (EFP0108) can be used with the following steps:

Step 1: Power VIO by connecting the USB cable to the reference board.

Step 2: Connect VIN (0.8V to 1.8V) through an external source or connect onboard a low voltage regulator by shorting ST208.

Step 3: Using Simplicity Studio – EFP Configuration Tool, load the desired register settings to the device.

Step 4: Connect load at the VOA terminal.

Case 2 [1.8V < Vin < 3.6V]

For source voltage more than 1.8V, the hardware of BRD8100A (EFP0108) can be modified similar to connections of EFP0109 with the following steps:

Step 1: Remove R201, R202, R203, R204, R205, R206.

Step 2: Connect R207

Step 3: Connect VDDB to VIN or LA2

Step 4: Connect external Host MCU using P202 and an additional common GND pin. Please note that external Host MCU such as EFM32/EFR32 starter kit will be required to program correct register settings into the EFP0108 after the initial start-up sequence.

Step 5: Create any sample project in Simplicity Studio 5 to utilize the existing I2C firmware, add software component of EFP01 instance to the project. Create a new function for EFP01, create new handle, initialize the EFP and add the following C code to the sample project:

sl_efp_write_register(efp, EFP01_I2C_CTRL, 0x09);

sl_efp_write_register(efp, EFP01_CC_CTRL,0x68);

sl_efp_write_register(efp, EFP01_EM_CRSREG_CTRL,0xE8);

sl_efp_write_register(efp, EFP01_VOA_V,0x34);

sl_efp_write_register(efp, EFP01_VOC_V,0x05);

sl_efp_write_register(efp, EFP01_VOB_EM0_V,0xAF);

sl_efp_write_register(efp, EFP01_VOB_EM2_V,0x2F);

sl_efp_write_register(efp,EFP01_BIAS_SW,0x0F);

sl_efp_write_register(efp, EFP01_BB_IPK,0x6C);

sl_efp_write_register(efp, EFP01_BB_CTRL3,0x17);

sl_efp_write_register(efp, EFP01_BB_CTRL5,0x9B);

sl_efp_write_register(efp, EFP01_BB_CTRL6,0x02);

sl_efp_write_register(efp, EFP01_LDOB_CTRL,0x0C);

sl_efp_write_register(efp, EFP01_LDOC_CTRL,0x8C);

sl_efp_write_register(efp, EFP01_LDOC_BB_CTRL,0xF0);

sl_efp_write_register(efp, EFP01_BK_CTRL0,0x00);

sl_efp_write_register(efp, EFP01_BK_CTRL1,0xFC);

sl_efp_write_register(efp, EFP01_BK_IPK,0x6C);

sl_efp_write_register(efp, EFP01_BK_CTRL2,0x50);

sl_efp_write_register(efp, EFP01_ADC_CC_CTRL,0x3F);

sl_efp_write_register(efp, EFP01_ADC_LIMITS,0x18);

Note that custom applications may have different register settings requirements than what is recommended above. Hence correct register values should be set by referring to the latest revision of the EFP01 datasheet.
The above settings will configure the outputs to the following voltages:
VOA = 3.33V
VOB = 1.17V
VOC = 1.86V

The maximum output voltage obtained at VOB will be limited to 1.2V rather than 3.3V as on EFP0109 due to the physical limitation and presence of EFP0108 on the development board.

Step 6: Power VIO from the external MCU board.

Step 7: Connect VIN (1.8V to 3.6V) through an external source.

Step 8: Load the register settings of EFP0108 using an external MCU.

Step 9: Connect the load at the VOA terminal.