Using S6BP203A for 4G Module Power – KBA220671

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Question: Can S6BP203A output 3.8 V for powering a 4G module?

 

Answer: 4G remote wireless communication module is included in the Telematics Box (T-Box) application. Many 4G modules require 3.8-V power supply (for example, http://www.telit.com/cellular/). Cypress automotive PMIC S6BP203A can be configured as follows for powering a 4G module.

 

Add two resistors to the FB pin as shown in Fig.1 instead of connecting the FB pin directly to the VOUT rail.

The tuned output voltage is calculated as follows:

Fig.1 Configuration to output 3.8V

To minimize the influence of the FB pin input resistance RFB, R1 and R2 should be much smaller than RFB, which is 2.53 MΩ (min) as shown in the datasheet. For 3.8-V output, the recommended value for R1 and R2 is: R1=36 kΩ, R2=270 kΩ.

As the side effect, R1 and R2 cause a little additional load current, . With the recommended resistor value, additional input current at no load condition will be lower than 10 µA.