Question: How do I tweak S6BP401A family output voltage?
Answer: S6BP401A is a family of 6-channel PMICs. MPNs in the S6BP401A family reflect the output voltage combinations of the six channels that are factory-configured. Because MPNs are available as limited samples, there might be the possibility that output voltages need to be tweaked at customer evaluation stage. Output voltages of the four DC/DC channels can be tweaked to a larger one as described below. However, note that output voltages of the two LDO channels cannot be adjusted).
To tweak the output voltage of the DDx channel (x: 1~4), add two resistors to the FBx pin as shown in Fig.1 instead of connecting FBx pin directly to VOUTx rail.
The tuned output voltage is calculated as following:
To minimize the influence of the FBx pin input resistance RFBx, R1 and R2 should be much smaller than RFBx, which is 95 k038F (min) as shown in the datasheet. A total resistance of about 10 kΩ is recommended for R1 and R2.
Note that this connection has the following side effects:
- R1 and R2 cause an additional load current, VOUTx / (R1 + R2) . However, the additional load current does not affect the efficiency because of the fixed PWM operation of the S6BP401A family.
- The discharge time becomes longer as follows (See the “Discharge Operation” section of the datasheet).
TDIS [ms] = 2.3 * (RDIS + R1) [kohm] * COUT [μF]