ISL62883 Datasheet, PDF (25/39 Pages) Intersil Corporation – Multiphase PWM Regulator for IMVP-6.5 Mobile CPUs and GPUs

Compensation & Current Sensing Network Design for Intersil Multiphase R^3 Regulators for IMVP-6.5
Jia Wei, [e-mail], 919-405-3605
Attention: 1. "Analysis ToolPak" Add-in is required. To turn on, go to Tools--Add-Ins, and check "Analysis ToolPak"
2. Green cells require user input
Compensator Parameters
Operation Parameters
Controller Part Number: ISL6288x
Phase Number:
3
Vin:
12 volts
Vo:
1.15 volts
Full Load Current:
51 Amps
A_V (s)
KZi
˜ Z_i
˜ _{¨¨©§}1
s
2Sf _z1
¸¸¹·
˜ _{¨¨©§}1
s
2Sf _z2
¸¸¹·
s
˜ _{¨¨©§}1
s
2Sf
p1
¸¸¹· ^˜ ¨¨©§^1
s
2Sf
p2
¸¸¹·
Estimated Full-Load Efficiency:
87 %
Number of Output Bulk Capacitors:
4
Capacitance of Each Output Bulk Capacitor:
270 uF
Recommended Value
User-Selected Value
ESR of Each Output Bulk Capacitor:
4.5 m :
R1
2.369 k :
R1
2.37 k :
ESL of Each Output Bulk Capacitor:
0.6 nH
R2 338.213 k :
R2
324 k :
Number of Output Ceramic Capacitors:
24
R3
0.530 k :
R3
0.536 k :
Capacitance of Each Output Ceramic Capacitor:
10 uF
C1 148.140 pF
C1
150 pF
ESR of Each Output Ceramic Capacitor:
3 m:
C2 455.369 pF
C2
390 pF
ESL of Each Output Ceramic Capacitor:
3 nH
C3
40.069 pF
C3
39 pF
Switching Frequency:
300 kHz
Inductance Per Phase:
CPU Socket Resistance:
0.36 uH
0.9 m :
Use User-Selected Value (Y/N)? N
Desired Load-Line Slope:
1.9 m :
Performance and Stability
Desired ISUM- Pin Current at Full Load:
40.9 uA
T1 Bandwidth: 212kHz
T2 Bandwidth: 66kHz
(This sets the over-current protection level)
T1 Phase Margin: 58.9°
T2 Phase Margin: 89.3°
Changing the settings in red requires deep understanding of control loop design
Place the 2nd compensator pole fp2 at:
2.2 xfs (Switching Frequency)
Tune KȦi to get the desired loop gain bandwidth
Tune the compensator gain factor KȦi:
1.3
(Recommended KȦi range is 0.8~2)








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Loop Gain, Gain Curve
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Output Impedance, Gain Curve
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Loop Gain, Phase Curve

Output Impedance, Phase Curve


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Current Sensing Network Parameters
Operation Parameters
Inductor DCR
0.88 m :
Rsum
3.65 k :
Rntc
10 k :
Rntcs
2.61 k :
Rp
11 k :
Recommended Value
Cn 0.406 uF
Ri 606.036 :
User Selected Value
Cn
0.406 uF
Ri
604 :
FIGURE 24. SCREENSHOT OF THE COMPENSATOR DESIGN SPREADSHEET