High Current Path During Abrupt Load Current Changes; High Current Path With Top And Bottom Mosfets Turned Off (Dead Time) - Intel EP80579 Manual

Figure 41. Buck Voltage Regulator Example
CO
6.6.3.1 High Current Path, Top MOSFET Turned ON
The dashed/arrow line in
MOSFET is ON. Current flows from the V_DC power source through the top MOSFET
(there may be more than one of these), the inductor and sense resistor, and finally, the
processor, R
not only carry the high current through the processor, but the power source and ground
must also be adequate.
Figure 42. High Current Path With Top MOSFET Turned ON
6.6.3.2 High Current Paths During Abrupt Load Current Changes
During abrupt changes in the load current, the bulk and decoupling capacitors must
supply current for the brief period before the regulator circuit may respond. The
dashed/arrow line in
resistance become a major concern and when they are not minimized, as they may
compromise the effectiveness of the capacitors. Bulk capacitors for Vcc must be located
at the highest current density points. These high-density points are located along the
shortest route between the processor core and the sense resistor. Using short, fat
traces or planes may minimize both stray inductance and resistance.
®
Intel EP80579 Integrated Processor Product Line
Platform Design Guide
74
®
Intel EP80579 Integrated Processor Product Line—System Power Delivery Guide
NMOS
DRIVER
TG
NMOS
BG
Voltage
IMVP-IV
Regulator
Control Feed back
Control Circuitry
Circuitry
Figure 42
, to ground. The components and current paths shown must be able to
Load
Voltage
Regulator
Control Circuitry
Figure 43 illustrates this current path. Stray inductance and
V_DC
SCHOTTKY
indicates the high current path when the top
Output Vcc
RLoad
May 2010
Order Number: 320068-005US