SLYT846 February   2024 TPS62870 , TPS62870-Q1 , TPS62871 , TPS62871-Q1 , TPS62872 , TPS62872-Q1 , TPS62873 , TPS62873-Q1 , TPS62874-Q1 , TPS62875-Q1 , TPS62876-Q1 , TPS62877-Q1 , TPS6287B10 , TPS6287B25 , TPSM8287A06 , TPSM8287A12 , TPSM8287A15

 

  1.   1
  2. 1Introduction
  3. 2DCS-Control topology overview
  4. 3Fixed-frequency DCS-Control topology overview
  5. 4Switching frequency variation
  6. 5Lower-ripple power-save mode
  7. 6Stacking (paralleling) for higher (or lower) load currents
  8. 7Conclusion
  9. 8References

2 DCS-Control topology overview

Figure 1 shows the basic block diagram of the DCS-Control topology [1]. Both the output-voltage sense (VOS) and feedback (FB) pins provide the inputs to the control loop for proper regulation. The VOS pin provides the topology’s fast transient response by directly feeding the output voltage into a ramp and then into the comparator, where it immediately affects the operating point. The FB pin is a lower-bandwidth path that provides highly accurate DC setpoint regulation. When combined in DCS-Control, the VOS pin’s AC path and FB pin’s DC path provide an accurate output voltage that also responds quickly to load transients.

GUID-20240129-SS0I-GRWT-SNMP-FRFGZPZZ2GCF-low.gif Figure 1 Block diagram of the DCS-Control topology.

A COT topology such as DCS-Control sets the on-time with a timer. By adjusting this on-time with the input and output voltage, the timer gives a reasonably constant frequency operation for most duty cycles in pulse-width modulation (PWM) mode. Equation 1 shows an example, where 416ns is the period for a 2.4MHz switching frequency:

Equation 1. t O N   =   V O U T V I N   ×   416 n s

However, the switching frequency is not precise enough for applications that require operation inside or outside of a specific frequency band. These applications generally require setting the switching frequency with an oscillator, such as in voltage- or current-mode control, and in some cases, the ability to synchronize with a system clock signal. Reference [2] offers further examples of the frequency variation of DCS-Control.