ncp5372 ON Semiconductor, ncp5372 Datasheet - Page 18

• Manufacturer Part Number: ncp5372
• Description: High Efficiency Two-phase Step-down Power Controller For Imvp-6.5 Mobile Cpu Core Power Supplies
• Manufacturer: ON Semiconductor

DAC slew rate
The DAC output is slew rate limited to prevent overshoot of the system output voltage. If the DAC voltage rises
significantly faster than that the control system can be achieved, the output voltage will overshoot. The DAC slew rate is
limited between 10mV/uS and 15mV/us.
Voltage Controlled Oscillator
The VCO is critical to the transient response of the overall system. When the load is stepped, the clock will turn on the
next phase’s one shot as fast as possible.
Current Sharing Function
By default, the one shot on times for both phases will be determined by the external resistor connected to TON, which is
used to ramp up the coil currents. Because of various reasons, the coil currents would not be match.
If V(CS1,CS1N) is larger than V(CS2,CS2N), the on time for Phase 1 and Phase 2 will be reduced and increased
respectively. The amount of adjustment will be based on their difference proportionally. (The detail amount of the
adjustment will be provided later.) The same operation would be applied when V(CS2,CS2N) is greater than
V(CS1,CS1N).
CS1N
CS1
CS2N
CS2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Rev0.3
1
1
1
1
1
1
1
1
1
1
1
Confidential and Proprietary – Not for Public Release
1
1
1
1
1
1
1
1
1
1
1
Figure 4. Forced Current Sharing Block Diagram
Rpole
Cpole
Rpole
0
0
0
1
1
1
1
1
1
1
1
ON Semiconductor CONFIDENTIAL
0
Mar 19, 2008 - Page 16
0
Cpole
1
1
1
0
0
0
0
1
1
1
1
-x
-x
x
0
1
1
0
0
1
1
0
0
1
1
x
1
0
1
0
1
0
1
0
1
0
1
R28
1k
F1
F
F3
F
0.0375
0.0250
0.0125
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
ISHARE
ISHARE
0
0
IONESHOT1
IONESHOT2