RT3606BE Datasheet, PDF (22/70 Pages) Richtek Technology Corporation – Dual Channel PWM Controller

RT3606BE
Applications information
The RT3606BE includes two voltage rails : a 3/2/1
multiphase synchronous buck controller, the CORE VR,
and a 2/1 multiphase synchronous buck controller, the
AXG VR, designed to meet Intel IMVP8 compatible CPUs
Current feedback signal
Comp signal
specification with a serial SVID control interface. The
controller uses an ADC to implement the all kinds of
settings to save total pin number for easy use and
increasing PCB space utilization. The RT3606BE is used _PWM1
in notebook, desktop computers and servers.
PWM2
General loop Function
PWM3
G-NAVP^TM Control Mode
The RT3606BE adopts the G-NAVP^TM controller, which is ^PWM4
a current mode constant on-time control with DC offset
cancellation. The approach can not only improve DC offset
problem for increasing system accuracy but also provide
Figure 1 (b). G-NAVP^TM CCM behavior waveforms in
CCM in Load Transient.
fast transient response. When current feedback signal
reaches comp signal, the RT3606BE generates an on-
time width to achieve PWM modulation. Figure 1 shows
the basic G-NAVP^TM behavior waveforms in continuous
conduct mode (CCM).
Diode Emulation Mode (DEM)
As well-known, the dominate power loss is switching
related loss during light load, hence VR needs to be
operated in asynchronous mode (or called discontinuous
conduct mode, DCM) to reduce switching related loss
Current feedback signal
since switching frequency is dependent on loading in the
asynchronous mode. The RT3606BE can operate in diode
emulation mode (DEM) to improve light load efficiency. In
DEM operation, the behavior of the low side MOSFET(s)
PWM1
Comp signal
needs to work like a diode, that is, the low side MOSFET(s)
will be turned on when the phase voltage is a negative
value, i.e. the inductor current follows from Source to Drain
PWM2
of low-side MOSFET(s). And the low-side MOSFET(s) will
be turned off when phase voltage is a positive value, i.e.
PWM3
reversed current is not allowed. Figure 2 shows the control
behavior in DEM. Figure 3 shows the G-NAVP^TM operation
PWM4
in DEM to illustrate the control behaviors. When load
Figure 1 (a). G-NAVP^TM CCM behavior waveforms in
CCM in Steady State
decreases, the discharge time of output capacitors
increases during UGATE and LGATE are turned off. Hence,
the switching frequency and switching loss will be reduced
to improve efficiency in light load condition.
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is a registered trademark of Richtek Technology Corporation.
DS3606BE-04 June 2017