SNVSC11 May 2022 LM25143-Q1
PRODUCTION DATA
To configure the LM25143-Q1 for multiphase operation (three or four phases), two LM25143-Q1 controllers are required. See Figure 9-10. Configure the first controller (CNTRL1) as a primary and the second controller (CNTRL2) as a secondary. To configure the second controller as a secondary, connect the MODE and FB2 pins to VDDA. This action disables both feedback error amplifiers of the secondary controller, placing them in a high-impedance state. Connect COMP1 and COMP2 of the primary and secondary together. Connect SS1 and SS2 of the primary and secondary together. Connect SYNCOUT of the primary controller to DEMB (SYNCIN) of the secondary. The SYNCOUT of the primary controller is 90° out-of-phase and facilitates interleaved operation. RT is not used for the oscillator when the LM25143-Q1 is in secondary mode but instead used for slope compensation. Therefore, select the RT resistance to be the same as that of the primary. The oscillator is derived from the primary controller. FPWM or DEM mode for the secondary is set by connecting its FB1 to VDDA or AGND, respectively. FPWM or DEM mode of the primary controller is set by its DEMB pin. See Table 9-3.
The LM25143-Q1 in single-output multiphase operation does not support phase shedding when the output voltage is set between 0.6 V to 1.5 V.
See the Benefits of a Multiphase Buck Converter white paper and Multiphase Buck Design From Start to Finish application report for more information.
Mode | FB1 (Secondary) | FB2 (Secondary) | DEM or FPWM (Secondary) |
---|---|---|---|
VDDA | AGND | VDDA | DEM |
VDDA | VDDA | VDDA | FPWM |