22.214.171.124.7 Step-Down Converters SMPS12 and SMPS123
The step-down converters SMPS1, SMPS2, and SMPS3 can be used in two different configurations:
- SMPS12 in dual-phase configuration supporting 6-A load current and SMPS3 in single-phase configuration supporting 3-A load current
- SMPS123 in triple-phase configuration supporting 9-A load current
SMPS1 and SMPS2 cannot be used as separate converters. In dual-phase configuration the two interleaved synchronous buck regulator phases with built-in current sharing operate in opposite phase. In triple-phase configuration the three interleaved synchronous buck regulator phases with built-in current sharing operate 120° out of phase. For light loads, the converter automatically changes to 1-phase operation.
Figure 6-6 shows the connections for dual-phase and triple-phase configurations.
a. Dual-Phase SMPS and Stand-Alone SMPS
Figure 6-6 Multi-Phase SMPS Connectivity
b. Triple Phase SMPS
To use the SMPS123 or SMPS12 and SMPS3 in the system:
- OTP defines dual-phase (SMPS12) operation, single-phase (SMPS3) operation, or triple-phase (SMPS123) operation. If SMPS123 mode is selected, the SMPS12 registers control SMPS123.
- By default SMPS123 and SMPS12 operate in multiphase mode for higher load currents and switch automatically to single-phase mode for low load currents. Forcing multiphase operation or single-phase operation by setting the SMPS_CTRL.SMPS123_PHASE_CTRL[1:0] bits when the SMPS123 or SMPS12 are loaded is also possible. Under no-load condition, do not force the multiphase operation, as this causes the SMPS to exhibit instability.