ZHCSIK3A July 2018 – January 2025 TPS650861
PRODUCTION DATA
BUCK1–BUCK6 support dynamic voltage scaling (DVS) for maximum system efficiency. The VR outputs can slew up and down in either 10mV or 25mV steps using the 7-bit voltage ID (VID) defined in Section 5.7 and Section 5.8. DVS slew rate is minimum 2.5mV/µs. In order to meet the minimum slew rate, VID progresses to the next code at 3µs (nom) interval per 10mV or at 6µs interval per 25mV steps. When DVS is active, the VR is forced into PWM mode, unless BUCKx_DECAY = 1, to ensure the output keeps track of VID code with minimal delay. Additionally, PGOOD is masked when DVS is in progress. Figure 6-5 shows an example of slew down and up from one VID to another (step size of
10 mV).
Figure 6-5 DVS Timing Diagram I (BUCKx_DECAY = 0)As shown in Figure 6-6, if BUCKx_VID[6:0] is set to 7b000 0000, its output voltage slews down to the minimum VID value first, and then drifts down to 0 V as the SMPS stops switching. Subsequently, if BUCKx_VID[6:0] is set to a value (neither 7b000 0000 nor 7b000 0001) when its output voltage is less than 0.5 V, the VR ramps up to 0.5 V first with soft-start kicking in, then slews up to target voltage in the slew rate mentioned previously. A fixed 200µs of soft-start time is reserved for VOUT to reach 0.5 V.
Figure 6-6 DVS Timing Diagram II (BUCKx_DECAY = 0)