2/3/4 Phase Buck Controller

NCP5381A
2/3/4 Phase Buck Controller
for VR10 and VR11 Pentium
IV Processor Applications
The NCP5381A is a two-- , three-- , or four-- phase buck controller
which combines differential voltage and current sensing, and
adaptive voltage positioning to power Intel’s most demanding
Pentium IV Processors and low voltage, high current power
supplies. Dual-- edge pulse-- width modulation (PWM) combined with
inductor current sensing reduces system cost by providing the fastest
initial response to transient loads thereby requiring less bulk and
ceramic output capacitors to satisfy transient load-- line requirements.
A high performance operational error amplifier is provided, which
allows easy compensation of the system. The proprietary method of
Dynamic Reference Injection makes the error amplifier
compensation virtually independent of the system response to VID
changes, eliminating the need for tradeoffs between load transients
and Dynamic VID performance.
Features

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
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Meets Intel’s VR 10.0, 10.1, 10.2, and 11.0 Specifications
Dual-- Edge PWM for Fastest Initial Response to Transient Loading
High Performance Operational Error Amplifier
Supports both VR11 and Legacy VR10 Soft-- Start Modes
Dynamic Reference Injection
8-- Bit DAC per Intel’s VR11 Specifications
DAC Range from 0.5 V to 1.6 V
0.5% System Voltage Accuracy
Remote Temperature Sensing per VR11
2, 3, or 4-- Phase Operation
True Differential Remote Voltage Sensing Amplifier
Phase-- to-- Phase Current Balancing
“Lossless” Differential Inductor Current Sensing
Differential Current Sense Amplifiers for each Phase
Adaptive Voltage Positioning (AVP)
Fixed No-- Load Voltage Positioning at –19 mV
Frequency Range: 100 kHz–1.0 MHz
Latched Overvoltage Protection (OVP)
Threshold Sensitive Enable Pin for VTT Sensing
Power Good Output with Internal Delays
Programmable Soft-- Start Time
Operates from 12 V
This is a Pb-- Free Device*
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MARKING
DIAGRAM
1
1
40
NCP5381A
AWLYYWWG
40 PIN QFN, 7x7
MN SUFFIX
CASE 488AG
NCP5381A = Specific Device Code
A
= Assembly Location
WL
= Wafer Lot
YY
= Year
WW
= Work Week
G
= Pb--Free Package
*Pin 41 is the thermal pad on the bottom of the device.
ORDERING INFORMATION
Device
NCP5381AMNR2G
Package
Shipping†
QFN--40 2500 / Tape & Reel
(Pb--Free)
†For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specification
Brochure, BRD8011/D.
*For additional information on our Pb--Free strategy
and soldering details, please download the
ON Semiconductor Soldering and Mounting
Techniques Reference Manual, SOLDERRM/D.
Applications




Pentium IV Processors
VRM Modules
Graphics Cards
Low Voltage, High Current Power Supplies
 Semiconductor Components Industries, LLC, 2010
November, 2010 - Rev. 5
1
Publication Order Number:
NCP5381A/D
NCP5381A
31
G2
32
G3
33
G4
34
35
DGND
36
VCC
37
VR_RDY
38
NTC
39
VR_FAN
VREF
CS3
NCP5381A
VID4
CS3N
(Top View)
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2
20
19
18
17
16
VR10/11
VDRP
CS1
VFB
VID7
COMP
CS2N
DIFFOUT
VID6
VS--
CS2
VS+
VID5
15
9
10
VID3
AGND
8
CS4N
14
7
VID2
ILIM
6
CS4
13
5
VID1
ROSC
4
DRVON
12
3
G1
VID0
SS
2
EN
11
1
VR_HOT
40
PIN CONNECTIONS
CS1N
30
29
28
27
26
25
24
23
22
21
NCP5381A
VREF
VR10/11
VID0
VID1
VID2
VID3
VID4
VID5
VID6
VID7
NTC
NCP5381A
VR_FAN
VR10/11
DAC
NTC
+
-
SS
VR_HOT
DAC
+
VS--
-
VS+
+
-
Diff Amp
DIFFOUT
Fault
1.3 V
+
VFB
Error Amp
COMP
VDRP
Droop
Amplifier
+
DGND
--
1.3 V
CS1
CS1N
+
-
+
-
ENB
G1
+
-
ENB
G2
+
-
ENB
G3
Gain = 6
CS2
CS2N
+
Gain = 6
CS3
CS3N
+
Gain = 6
CS4
CS4N
+
-
+
-
ENB
G4
4OFF
Gain = 6
OVER
Oscillator
ROSC
Fault
DIFFOUT
1.3 V
+
ILIM
Current Limit
EN
VCC
+
AGND
9.0 V
UVLO
Figure 1. Simplified Block Diagram
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3
Fault Logic
3 Phase
Detect
and
Monitor
Circuits
DRVON
VR_RDY
NCP5381A
12 V_FILTER
+12 V
VTT
680 Ω PULLUPS
12 V_FILTER
D1
BAT54HT1
C4
RVCC
C3
CVCC1
NCP3418B
36
4
35
RT1
U20
2
VID0
3
VID1
4
VID2
5
VID3
6
VID4
7
VID5
8
VID6
9
VID7
10
VID_SEL
1
VR_EN
37
VR_RDY
40
VR_HOT
39
VR_FAN
16
15
RISO1
CFB1
RFB1
RFB
VID0
DGND
VID1
AGND
VID2
VID3
VREF
VID4
NTC
VID5
RNTC2
14
34
19
SW
DRVL
IN
PGND
C1
8
5
6
CD1
RD1
CF
RF
18
R2
C2
RS1
CS1
VID7
VR10/11
G2
EN
VR_RDY
12 V_FILTER
31
12 V_FILTER
24
CS2
CS2N 23
VR_HOT
VR_FAN
VS--
G3
VS+
4
32
3
26
G4
DIFFOUT
2
VCC
BST
DRVH
OD
SW
DRVL
IN
PGND
1
8
7
5
6
33
28
CS4
CS4N 27
VFB
12 V_FILTER
20
L1
7
NTD85N02RT4
38
NCP5381A CS3N 25
17
OD
NTD60N02RT4
1
RNTC1
RDRP
CH
2
BST
DRVH
30
G1
22
CS1
CS1N 21
VID6
CS3
RISO2
RT2
3
VCC
VCC
VDRP
DRVON
12 V_FILTER
29
COMP
ILIM
ROSC SS
13
12
4
11
3
RLIM1
CSS
2
VCC
BST
DRVH
OD
SW
DRVL
IN
PGND
1
8
7
5
6
RLIM2
12 V_FILTER
4
3
2
VCC
12 V_FILTER
BST
DRVH
OD
SW
DRVL
IN
PGND
1
8
7
5
6
RT2 LOCATED NEAR OUTPUT INDUCTORS
VCCP
+
VSSP
CPU GND
Figure 2. Application Schematic for Four Phases
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4
NCP5381A
12 V_FILTER
+12 V
VTT
680 Ω PULLUPS
C4
RVCC
C3
CVCC1
NCP3418B
36
4
35
U1
2
VID0
3
VID1
4
VID2
5
VID3
6
VID4
7
VID5
8
VID6
9
VID7
10
VID_SEL
1
VR_EN
37
VR_RDY
40
VR_HOT
39
VR_FAN
16
15
RISO1
CFB1
RT1
VID0
DGND
VID1
AGND
VID2
VID3
VREF
VID4
NTC
VID5
14
34 RNTC1
19
BST
DRVH
OD
SW
DRVL
IN
PGND
C1
8
5
6
VID7
VR10/11
G2
EN
VR_RDY
12 V_FILTER
31
RD1
CF
RF
18
R2
RS1
C2
12 V_FILTER
24
CS2
CS2N 23
VR_HOT
VR_FAN
VS--
G3
VS+
4
32
3
26
G4
DIFFOUT
2
VCC
BST
DRVH
OD
SW
DRVL
IN
PGND
1
8
7
5
6
33
28
CS4
CS4N 27
VFB
12 V_FILTER
CD1
L1
7
CS1
RDRP
20
NTD60N02RT4
1
NTD85N02RT4
38
NCP5381A CS3N 25
17
CH
2
RNTC2
VCC
30
G1
22
CS1
CS1N 21
VID6
RFB1
RFB
3
VCC
CS3
RISO2
RT2
12 V_FILTER
D1
BAT54HT1
VDRP
DRVON
12 V_FILTER
29
COMP
ILIM
ROSC SS
13
12
RLIM1
4
11
3
CSS
2
VCC
BST
DRVH
OD
SW
DRVL
IN
PGND
1
8
7
5
6
RLIM2
RT2 LOCATED NEAR OUTPUT INDUCTORS
VCCP
+
VSSP
CPU GND
Figure 3. Application Schematic for Three Phases
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5
NCP5381A
12 V_FILTER
+12 V
VTT
680 Ω PULLUPS
RVCC
CVCC1
NCP3418B
4
35
U21
VID0
3
VID1
4
VID2
5
VID3
6
VID4
7
VID5
8
VID6
9
VID7
10
VID_SEL
1
VR_EN
37
VR_RDY
40
VR_HOT
39
VR_FAN
16
15
RISO1
CFB1
RFB1
RFB
3
VCC
VID0
DGND
VID1
AGND
VID2
VID3
VREF
VID4
NTC
RNTC2
14
34
2
RNTC1
19
BST
DRVH
OD
SW
DRVL
IN
PGND
C1
NTD60N02RT4
1
8
L1
7
5
6
R2
RS1
NTD85N02RT4
38
C2
CS1
VID7
VR10/11
G2
EN
VR_RDY
12 V_FILTER
31
12 V_FILTER
24
CS2
CS2N 23
VR_HOT
VR_FAN
VS--
G3
VS+
4
32
3
26
NCP5381A CS3N 25
17
VCC
30
G1
22
CS1
CS1N 21
VID6
CS3
RISO2
RT2
RT1
VID5
C4
C3
36
2
12 V_FILTER
D1
BAT54HT1
G4
DIFFOUT
2
VCC
BST
DRVH
OD
SW
DRVL
IN
PGND
1
8
7
5
6
33
28
CS4
CS4N 27
VFB
RDRP
20
CD1
RD1
CF
RF
18
CH
VDRP
DRVON
29
COMP
ILIM
ROSC SS
13
12
11
RLIM1
CSS
RLIM2
RT2 LOCATED NEAR OUTPUT INDUCTORS
VCCP
+
VSSP
CPU GND
Figure 4. Application Schematic for Two Phases
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6
NCP5381A
PIN DESCRIPTIONS
Pin No.
Symbol
Description
1
EN
Pull this pin high to enable controller. Pull this pin low to disable controller. Either an open--collector output
(with a pull--up resistor) or a logic gate (CMOS or totem--pole output) may be used to drive this pin. A Low to
High transition on this pin will initiate a soft start. If the Enable function is not required, this pin should be tied
directly to VREF.
2–9
VID0–VID7
Voltage ID DAC inputs.
10
VR10/VR11
VR select bit. Connect this pin to VTT (1.25 V) to select the VR11 DAC table. Ground this pin to select the
VR10 DAC table with VR11 type startup. Connect this pin to VREF (4 V) to select VR10 DAC table with
legacy VR10 type startup.
11
SS
12
ROSC
A resistance from this pin to ground programs the oscillator frequency. Also, this pin supplies a regulated
2.0 V which may be used with a voltage divider to the ILIM pin to set the over current shutdown threshold as
shown in the Applications Schematics.
13
ILIM
Over current shutdown threshold. To program the shutdown threshold, connect this pin to the ROSC pin via a
resistor divider as shown in the Applications Schematics. To disable the over current feature connect this pin
directly to the ROSC pin. To guarantee correct operation, this pin should only be connected to the voltage
generated by the ROSC pin – do not connect this pin to any externally generated voltages.
14
AGND
15
VS+
Non--inverting input to the internal differential remote VCORE sense amplifier.
16
VS--
Inverting input to the internal differential remote VCORE sense amplifier.
17
DIFFOUT
18
COMP
19
VFB
20
VDRP
Current signal output for Adaptive Voltage Positioning (AVP). The voltage of this pin minus 1.3 V is
proportional to the output current. Connect a resistor from this pin to VFB to set the amount of AVP current
into the feedback resistor (RFB) to produce an output voltage droop. Leave this pin open for no AVP.
21, 23,
25, 27
CSxN
Inverting input to current sense amplifier #x, x = 1, 2, 3, 4.
22, 24,
26, 28
CSx
29
DRVON
Gate Driver enable output. This pin produces a logic HIGH to enable gate drivers and a logic LOW to disable
gate drivers and has an internal 70 kΩ to ground.
30 – 33
G1 – G4
PWM control signal outputs to gate drivers.
34
VREF
Voltage reference pin. This pin may be used to implement remote NTC temperature sensing as shown in the
Applications Schematic.
35
DGND
Power supply return for the digital circuits. Connect to AGND.
36
VCC
37
VR_RDY
Voltage Regulator Ready (PowerGood) output. Open drain type output with internal delays that will transition
High when VCORE is higher than 300 mV below DAC, Low when VCORE is lower than 380 mV below DAC,
and Low when VCORE is higher than DAC+185 mV. This output is latched Low if VCORE exceeds DAC+185
mV until VCC is removed.
38
NTC
Remote temperature sense connection. Connect an NTC thermistor from this pin to GND and a resistor from
this pin to VREF. As the NTC’s temperature increases the voltage on this pin will decrease.
39
VR_FAN
Open drain type of output that will be low impedance when the voltage at the NTC pin is above 1.416 V.
This pin will transition to a high impedance state when the voltage at the NTC pin decreases below 1.176 V.
40
VR_HOT
Open drain type of output that will be low impedance when the voltage at the NTC pin is above 1.086 V.
This pin will transition to a high impedance state when the voltage at the NTC pin decreases below 0.846 V.
41
THPAD
Copper pad on the bottom of the IC for heatsinking. This pin should be connected to the ground plane under
the IC.
A capacitor from this pin to ground programs the soft--start time.
Power supply return for the analog circuits that control output voltage.
Output of the differential remote sense amplifier.
Output of the error amplifier.
Error amplifier inverting input. Connect a resistor from this pin to DIFFOUT. The value of this resistor and the
amount of current from the droop resistor (RDRP) will set the amount of output voltage droop (AVP) during
load.
Non--inverting input to current sense amplifier #x, x = 1, 2, 3, 4.
Power for the internal control circuits.
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7
NCP5381A
MAXIMUM RATINGS
Rating
Value
Unit
Operating Ambient Temperature Range
0 to 70
C
Operating Junction Temperature Range
0 to 85
C
--55 to 150
C
Lead Temperature Soldering, Reflow (60 to 120 seconds minimum above 237C):
260
C
Thermal Resistance, Junction--to--Ambient (RJA) on a thermally conductive PCB in free air
83
C/W
JEDEC Moisture Sensitivity Level
3
MSL
Maximum Voltage – VCC pin with respect to AGND
15
V
Maximum Voltage – all other pins with respect to AGND
5.5
V
Minimum Voltage – all pins with respect to AGND
--0.3
V
Maximum Current into pins: COMP, VDRP, DIFFOUT, VREF
3.0
mA
Maximum Current into pins: VR_RDY, G1, G2, G3, G4, SS, VR_FAN, VR_HOT, DRVON
20
mA
Maximum Current out of pins: COMP, VDRP, DIFFOUT, ROSC, VREF
3.0
mA
Maximum Current out of pins: G1, G2, G3, G4
20
mA
Storage Temperature Range
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
NOTE: ESD Sensitive Device.
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8
NCP5381A
ELECTRICAL CHARACTERISTICS
(0C < TA < 70C; 0C < TJ < 85C; 10.8 V < VCC < 13.2 V; All DAC Codes; CVCC = 0.1 mF, FSW = 400 kHz, unless otherwise stated)
Parameter
Test Conditions
Min
Typ
Max
Units
--200
--50
--10
nA
--
1.3
--
V
--1.0
--
1.0
mV
Error Amplifier
Input Bias Current
Inverting Input Voltage
1.0 kΩ between VFB and COMP Pins
Input Offset Voltage (Note 1)
Open Loop DC Gain (Note 1)
CL = 60 pF to GND,
RL = 10 kΩ to GND
--
78
--
dB
Open Loop Unity Gain Bandwidth
(Note 1)
CL = 60 pF to GND,
RL = 10 kΩ to GND
--
15
--
MHz
Open Loop Phase Margin (Note 1)
CL = 60 pF to GND,
RL = 10 kΩ to GND
--
65
--
deg
Slew Rate (Note 1)
ΔVin = 100 mV, G = --1.0 V/V,
1.2 V < Vout < 2.2 V,
CL = 60 pF,
DC Load = 125 mA
--
5.0
--
V/ms
Maximum Output Voltage
ISOURCE = 1.0 mA
3.0
3.3
--
V
Minimum Output Voltage
ISINK = 1.0 mA
--
0.9
1.0
V
Output Source Current (Note 1)
Vout = 3.0 V
--
2.0
--
mA
Output Sink Current (Note 1)
Vout = 1.0 V
--
2.0
--
mA
Remote Sense Differential Amplifier
VS+ Input Resistance (Note 1)
DRVON = High
DRVON = Low
---
17
0.5
---
kΩ
VS+ Input Open Circuit Voltage
(Note 1)
DRVON = High
DRVON = Low
---
0.67
0.05
---
V
VS-- Input Resistance (Note 1)
VS+ = DAC Voltage
DRVON = High
--
10
--
kΩ
VS-- Input Open Circuit Voltage
(Note 1)
DRVON = High
VS+ = DAC Voltage
=
0.333*DA
C
+ 0.433
V
Input Voltage Range
--0.3
--
3.0
V
Input Offset Voltage (Note 1)
--1.0
--
1.0
mV
--
12
--
MHz
0.982
1.000
1.018
V/V
--
10
--
V/ms
3.0
--
--
V
--3dB Bandwidth (Note 1)
CL = 80 pF to GND,
RL = 10 kΩ to GND
DC Gain
IDIFFOUT = 100 mA
Slew Rate (Note 1)
ΔVin = 1.0 V,
ΔVout = 1.0 V to 2.0 V,
CL = 80 pF to GND,
Load = 125 mA
Maximum Output Voltage
ISOURCE = 1.0 mA
Minimum Output Voltage
ISINK = 1.0 mA
--
--
0.5
V
Output Source Current (Note 1)
Vout = 2.1 V
--
25
--
mA
Output Sink Current (Note 1)
Vout = 1.0 V
--
1.4
--
mA
1. Guaranteed by design. Not tested in production.
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9
NCP5381A
ELECTRICAL CHARACTERISTICS
(0C < TA < 70C; 0C < TJ < 85C; 10.8 V < VCC < 13.2 V; All DAC Codes; CVCC = 0.1 mF, FSW = 400 kHz, unless otherwise stated)
Parameter
Test Conditions
Min
Typ
Max
Units
5.7
6.0
6.3
V/V
VDRP Adaptive Voltage Positioning Amplifier
Current Sense Input to VDRP Gain
--60 mV < (CSx--CSxN)
< +60 mV, TA = 25C
Current Sense Input to VDRP Output
--3dB Bandwidth (Note 1)
CL = 330 pF to GND,
RL = 10 kΩ to GND
--
7.2
--
MHz
Current Sense Input to VDRP Output
Slew Rate (Note 1)
ΔV(CSx--CSxN) = 25 mV (all
phases), 1.3 V < Vout < 1.9 V,
CL = 330 pF to GND,
Load = 400 mA
--
3.7
--
V/ms
Current Summing Amp Output Offset
Voltage
CSx – CSxN = 0, CSx =1.0 V
--15
--
+15
mV
Maximum VDRP Output Voltage
CSx -- CSxN = 0.12 V
(all phases),
ISOURCE = 1.0 mA
3.02
--
--
V
Minimum VDRP Output Voltage
CSx -- CSxN = --0.12 V
(all phases),
ISINK = 1.0 mA
--
--
0.5
V
Output Source Current (Note 1)
VDRP = 2.9 V
--
9.0
--
mA
Output Sink Current (Note 1)
VDRP = 1.0 V
--
2.0
--
mA
--200
--100
--
nA
Common Mode Input Voltage Range
(Note 1)
--0.3
--
2.0
V
Differential Mode Input Voltage Range
--120
--
120
mV
Current Sense Amplifiers
Input Bias Current
CSx = CSxN = 1.4 V
Input Offset Voltage (Note 1)
CSx = CSxN = 1.0 V
--3.0
--
3.0
mV
Current Sense Input to
PWM Comparator Input Gain
0 mV < (CSx--CSxN) < 25 mV
TA = 25C
5.7
6.0
6.3
V/V
100
--
1000
kHz
Oscillator
Switching Frequency Range (Note 1)
Switching Frequency Accuracy
(Note 1)
ROSC = 100 kΩ, 2 or 4--phase
93.6
104
114.4
kHz
Switching Frequency Accuracy
ROSC = 49.9 kΩ, 2 or 4--phase
184.5
205
225.5
kHz
Switching Frequency Accuracy
ROSC = 24.9 kΩ, 2 or 4--phase
360
400
440
kHz
Switching Frequency Accuracy
ROSC = 10 kΩ, 2 or 4--phase
829
921
1013
kHz
Switching Frequency Accuracy
(Note 1)
ROSC = 100 kΩ, 3--phase
90
100
110
kHz
Switching Frequency Accuracy
ROSC = 49.9 kΩ, 3--phase
178.2
198
217.8
kHz
Switching Frequency Accuracy
ROSC = 24.9 kΩ, 3--phase
351
390
429
kHz
Switching Frequency Accuracy
ROSC = 10 kΩ, 3--phase
818
909
1000
kHz
ROSC Output Voltage
10 kΩ < ROSC < 49.9 kΩ
1.92
2.00
2.08
V
ROSC Output Voltage (Note 1)
49.9 kΩ < ROSC < 100 kΩ
--
2.00
--
V
1. Guaranteed by design. Not tested in production.
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10
NCP5381A
ELECTRICAL CHARACTERISTICS
(0C < TA < 70C; 0C < TJ < 85C; 10.8 V < VCC < 13.2 V; All DAC Codes; CVCC = 0.1 mF, FSW = 400 kHz, unless otherwise stated)
Parameter
Test Conditions
Min
Typ
Max
Units
--
30
40
ns
--
1.0
--
V
Modulators (PWM Comparators)
Minimum Pulse Width
Fs = 400 kHz
Magnitude of the PWM Ramp
0% Duty Cycle
COMP voltage when the PWM
outputs remain LO
--
1.2
--
V
100% Duty Cycle
COMP voltage when the PWM
outputs remain HI
--
2.3
--
V
Minimum PWM Linear Duty Cycle
(Note 1)
FS = 400 kHz
--
90
--
%
PWM Comparator Offset Mismatch
(Note 1)
Between any 2 phases,
FS = 400 kHz
--
--
40
mV
Phase Angle Error
Between adjacent phases,
FS = 400 kHz
--15
--
15

Propagation Delay (Note 1)
Ramp/Comp crossing to Gx high
--
20
--
ns
Propagation Delay (Note 1)
Ramp/Comp crossing to Gx low
--
20
--
ns
3.3
4.0
4.7
V
PWM Outputs
Output High Voltage
Sourcing 500 mA
Output Low Voltage
Sinking 500 mA
--
25
100
mV
Rise Time
CL = 20 pF, ΔVo = 0.3 to 2.0 V
--
10
--
ns
Fall Time
CL = 20 pF, ΔVo = Vmax to 0.7 V
--
10
--
ns
Output Impedance – LO State
Resistance to GND (Gx = LO)
--
50
--
Ω
G4 Gate Pin Source Current during
Phase Detect
--
70
--
mA
Phase Detection Period
--
50
--
ms
G4 Phase Detect Threshold
Resistance
--
--
1.0
kΩ
Gate Driver Enable (DRVON)
Output High Voltage
Sourcing 500 mA
4.0
5.3
5.5
V
Output Low Voltage
Sinking 500 mA
--
50
200
mV
Rise Time
CL (PCB) = 20 pF,
ΔVo = 10% to 90%
--
25
--
ns
Fall Time
CL (PCB) = 20 pF,
ΔVo = 10% to 90%
--
25
--
ns
Internal Pulldown Resistance
VCC < UVLO Threshold
--
70
140
kΩ
1. Guaranteed by design. Not tested in production.
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11
NCP5381A
ELECTRICAL CHARACTERISTICS
(0C < TA < 70C; 0C < TJ < 85C; 10.8 V < VCC < 13.2 V; All DAC Codes; CVCC = 0.1 mF, FSW = 400 kHz, unless otherwise stated)
Parameter
Test Conditions
Min
Typ
Max
Units
VR_RDY (Power Good) Output
Saturation Voltage
ISINK = 10 mA
--
--
0.4
V
Rise Time
External pullup of 1.0 kΩ to 1.25 V,
CLOAD = 20 pF,
ΔVo = 10% to 90%
--
--
150
ns
Output Voltage at Power--up (Note 1)
External VR_RDY pullup resistor of
2.0 kΩ to 5.0 V,
tR_VCC  3 x tR_5V,
--
--
1.0
V
100 ms  tR_VCC  20 ms
High – Output Leakage Current
VR_RDY = 5.5 V via 1.0 K
--
--
1.0
mA
Upper Threshold Voltage
VCORE increasing,
DAC = 1.3 V
--
300
--
mV below
DAC
Rising Delay
VCORE increasing
0.3
1.40
2.0
ms
Falling Delay
VCORE decreasing
--
5.0
--
ms
mA
VR_FAN AND VR_HOT
NTC Pin Bias Current
0 V < NTC < 5.0 V
--1.0
--
1.0
VR_FAN Upper Voltage Threshold
Fraction of VREF voltage above
which VR_FAN output pulls low
0.3518
0.3625
0.3737
VR_FAN Lower Voltage Threshold
Fraction of VREF voltage below
which VR_FAN output is open
0.2892
0.3025
0.3112
210
240
270
mV
--
--
1.0
V
VR_FAN Hysteresis
VR_FAN Output Voltage at Powerup
(Note 1)
External Pullup resistor of 2.0 kΩ to
5.0 V,
tR_VCC  3 x tR_5V,
100 ms  tR_VCC  20 ms
VR_FAN Output Saturation Voltage
ISINK = 4.0 mA
--
--
0.3
V
VR_FAN Output Leakage Current
High Impedance State,
VR_FAN = 5.0 V
--
--
1.0
mA
VR_HOT Upper Voltage Threshold
Fraction of VREF voltage above
which VR_HOT output pulls low
0.2732
0.2815
0.2897
VR_HOT Lower Voltage Threshold
Fraction of VREF voltage below
which VR_HOT output is open
0.2107
0.2190
0.2272
210
240
270
mV
--
--
1.0
V
VR_HOT Hysteresis
VR_HOT Output Voltage at Powerup
(Note 1)
External Pullup resistor of 2.0 kΩ to
5.0 V,
tR_VCC  3 x tR_5V,
100 ms  tR_VCC  20 ms
VR_HOT Saturation Output Voltage
ISINK = 4.0 mA
--
--
0.3
V
VR_HOT Output Leakage Current
High Impedance State,
VR_HOT = 5.0 V
--
--
1.0
mA
1. Guaranteed by design. Not tested in production.
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12
NCP5381A
ELECTRICAL CHARACTERISTICS
(0C < TA < 70C; 0C < TJ < 85C; 10.8 V < VCC < 13.2 V; All DAC Codes; CVCC = 0.1 mF, FSW = 400 kHz, unless otherwise stated)
Parameter
Test Conditions
Min
Typ
Max
Units
--
5.0
--
mA
Soft--Start
SS Pin Source Current
ENABLE = HI, VSS PIN < 1.1 V
SS Pin Source Current
ENABLE = HI, VSS PIN > 1.15 V,
VR11 SS mode only
125
--
--
mA
Soft--Start Ramp Time
CSS = 0.01
PIN = 1.1 V
1.5
2.2
3.0
ms
SS Pin Discharge Voltage
ENABLE = LO
--
--
50
mV
Soft--Start Discharge Time
From ENABLE = LO to VSS PIN <
max Discharge Voltage,
CSS = 0.01 mF
--
5.0
--
ms
--
1.081
--
V
50
225
900
ms
mF, DRVON = HI to VSS
VR11 VBOOT Threshold Voltage
VR11 Dwell Time at VBOOT (Note 1)
Enable Input
Enable High Input Leakage Current
EN = 3.0 V
--
--
10
mA
Upper Threshold
VUPPER
0.80
0.85
0.90
V
Lower Threshold
VLOWER
0.67
0.75
0.83
V
Total Hysteresis
VUPPER – VLOWER
70
100
130
mV
Enable Delay Time
Enable transitioning HI to start of SS
voltage rise
0.5
1.5
3.0
ms
Disable Delay Time
Enable transitioning Low to
DRVON = Low
--
--
200
ns
5.7
6.0
6.3
V/V
--
0.1
1.0
mA
ILIM Pin Working Voltage Range
(Note 1)
0.3
--
2.0
V
ILIM Input Offset Voltage (Note 1)
--50
--
50
mV
DAC+160
DAC+180
DAC+200
mV
UVLO Start Threshold
8.2
9.0
9.5
V
UVLO Stop Threshold
7.2
8.0
8.5
V
--
1.0
--
V
Current Limit
Current Sense Inputs to ILIM Gain
(Note 1)
20 mV < (CSx--CSxN) < 60 mV
TA = 25C
(all CS channels together)
ILIM Pin Input Bias Current
VILIM = 2.0 V
Overvoltage Protection
Overvoltage Threshold (Note 1)
Undervoltage Protection
UVLO Hysteresis
VID Inputs
Upper Threshold
VUPPER
--
--
800
mV
Lower Threshold
VLOWER
400
--
--
mV
Input Bias Current
VVIDX = 1.25 V
--
100
500
nA
Delay before Latching VID Change
(VID De--Skewing)
Measured from the 1st edge of a VID
change
400
--
1000
ns
1. Guaranteed by design. Not tested in production.
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13
NCP5381A
ELECTRICAL CHARACTERISTICS
(0C < TA < 70C; 0C < TJ < 85C; 10.8 V < VCC < 13.2 V; All DAC Codes; CVCC = 0.1 mF, FSW = 400 kHz, unless otherwise stated)
Parameter
Test Conditions
Min
Typ
Max
Units
VR10/VR11 DAC Table Threshold
0.55
--
0.775
V
VR10 w/ Legacy SS/VR11 Threshold
2.7
--
3.1
V
VR10/VR11 Select
Internal DAC Slew Rate Limiter
Positive Slew Rate Limit
VID step range of +10mV to +500mV
--
7.3
--
mV/ms
Negative Slew Rate Limit
VID step range of --10mV to --500mV
--
7.3
--
mV/ms
3.92
4.00
4.08
V
--
20
--
mA
Voltage Reference (VREF)
VREF Output Voltage
0 < IVREF < 250 mA
Input Supply Current
VCC Operating Current
FSW = 400 kHz
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14
NCP5381A
ELECTRICAL CHARACTERISTICS
(0C < TA < 70C; 0C < TJ < 85C; 10.8 V < VCC < 13.2 V; All DAC Codes; CVCC = 0.1 mF, FSW = 400 kHz, unless otherwise stated)
Parameter
Test Conditions
Min
Typ
Max
Units
--
--
0.5
5.0
8.0
%
mV
mV
VR10 DAC
System Voltage Accuracy
1.0 V < DAC < 1.6 V
0.8 V < DAC < 1.0 V
0.5 V < DAC < 0.8 V
No--Load Offset Voltage from
Nominal DAC Specification
With CS Input ΔVin = 0 V
--19
mV
VR10 VID Codes
VID4
400 mV
VID3
200 mV
VID2
100 mV
VID1
50 mV
VID0
25 mV
VID5
12.5 mV
VID6
6.25 mV
Nominal DAC
Voltage (V)
0
1
0
1
0
1
1
1.60000
0
1
0
1
0
1
0
1.59375
0
1
0
1
1
0
1
1.58750
0
1
0
1
1
0
0
1.58125
0
1
0
1
1
1
1
1.57500
0
1
0
1
1
1
0
1.56875
0
1
1
0
0
0
1
1.56250
0
1
1
0
0
0
0
1.55625
0
1
1
0
0
1
1
1.55000
0
1
1
0
0
1
0
1.54375
0
1
1
0
1
0
1
1.53750
0
1
1
0
1
0
0
1.53125
0
1
1
0
1
1
1
1.52500
0
1
1
0
1
1
0
1.51875
0
1
1
1
0
0
1
1.51250
0
1
1
1
0
0
0
1.50625
0
1
1
1
0
1
1
1.50000
0
1
1
1
0
1
0
1.49375
0
1
1
1
1
0
1
1.48750
0
1
1
1
1
0
0
1.48125
0
1
1
1
1
1
1
1.47500
0
1
1
1
1
1
0
1.46875
1
0
0
0
0
0
1
1.46250
1
0
0
0
0
0
0
1.45625
1
0
0
0
0
1
1
1.45000
1
0
0
0
0
1
0
1.44375
1
0
0
0
1
0
1
1.43750
1
0
0
0
1
0
0
1.43125
1
0
0
0
1
1
1
1.42500
1
0
0
0
1
1
0
1.41875
1
0
0
1
0
0
1
1.41250
1
0
0
1
0
0
0
1.40625
1
0
0
1
0
1
1
1.40000
1
0
0
1
0
1
0
1.39375
1
0
0
1
1
0
1
1.38750
1
0
0
1
1
0
0
1.38125
1
0
0
1
1
1
1
1.37500
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15
NCP5381A
VR10 VID Codes
VID4
400 mV
VID3
200 mV
VID2
100 mV
VID1
50 mV
VID0
25 mV
VID5
12.5 mV
VID6
6.25 mV
Nominal DAC
Voltage (V)
1
0
0
1
1
1
0
1.36875
1
0
1
0
0
0
1
1.36250
1
0
1
0
0
0
0
1.35625
1
0
1
0
0
1
1
1.35000
1
0
1
0
0
1
0
1.34375
1
0
1
0
1
0
1
1.33750
1
0
1
0
1
0
0
1.33125
1
0
1
0
1
1
1
1.32500
1
0
1
0
1
1
0
1.31875
1
0
1
1
0
0
1
1.31250
1
0
1
1
0
0
0
1.30625
1
0
1
1
0
1
1
1.30000
1
0
1
1
0
1
0
1.29375
1
0
1
1
1
0
1
1.28750
1
0
1
1
1
0
0
1.28125
1
0
1
1
1
1
1
1.27500
1
0
1
1
1
1
0
1.26875
1
1
0
0
0
0
1
1.26250
1
1
0
0
0
0
0
1.25625
1
1
0
0
0
1
1
1.25000
1
1
0
0
0
1
0
1.24375
1
1
0
0
1
0
1
1.23750
1
1
0
0
1
0
0
1.23125
1
1
0
0
1
1
1
1.22500
1
1
0
0
1
1
0
1.21875
1
1
0
1
0
0
1
1.21250
1
1
0
1
0
0
0
1.20625
1
1
0
1
0
1
1
1.20000
1
1
0
1
0
1
0
1.19375
1
1
0
1
1
0
1
1.18750
1
1
0
1
1
0
0
1.18125
1
1
0
1
1
1
1
1.17500
1
1
0
1
1
1
0
1.16875
1
1
1
0
0
0
1
1.16250
1
1
1
0
0
0
0
1.15625
1
1
1
0
0
1
1
1.15000
1
1
1
0
0
1
0
1.14375
1
1
1
0
1
0
1
1.13750
1
1
1
0
1
0
0
1.13125
1
1
1
0
1
1
1
1.12500
1
1
1
0
1
1
0
1.11875
1
1
1
1
0
0
1
1.11250
1
1
1
1
0
0
0
1.10625
1
1
1
1
0
1
1
1.10000
1
1
1
1
0
1
0
1.09375
1
1
1
1
1
0
1
OFF
1
1
1
1
1
0
0
OFF
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16
NCP5381A
VR10 VID Codes
VID4
400 mV
VID3
200 mV
VID2
100 mV
VID1
50 mV
VID0
25 mV
VID5
12.5 mV
VID6
6.25 mV
Nominal DAC
Voltage (V)
1
1
1
1
1
1
1
OFF
1
1
1
1
1
1
0
OFF
0
0
0
0
0
0
1
1.08750
0
0
0
0
0
0
0
1.08125
0
0
0
0
0
1
1
1.07500
0
0
0
0
0
1
0
1.06875
0
0
0
0
1
0
1
1.06250
0
0
0
0
1
0
0
1.05625
0
0
0
0
1
1
1
1.05000
0
0
0
0
1
1
0
1.04375
0
0
0
1
0
0
1
1.03750
0
0
0
1
0
0
0
1.03125
0
0
0
1
0
1
1
1.02500
0
0
0
1
0
1
0
1.01875
0
0
0
1
1
0
1
1.01250
0
0
0
1
1
0
0
1.00625
0
0
0
1
1
1
1
1.00000
0
0
0
1
1
1
0
0.99375
0
0
1
0
0
0
1
0.98750
0
0
1
0
0
0
0
0.98125
0
0
1
0
0
1
1
0.97500
0
0
1
0
0
1
0
0.96875
0
0
1
0
1
0
1
0.96250
0
0
1
0
1
0
0
0.95625
0
0
1
0
1
1
1
0.95000
0
0
1
0
1
1
0
0.94375
0
0
1
1
0
0
1
0.93750
0
0
1
1
0
0
0
0.93125
0
0
1
1
0
1
1
0.92500
0
0
1
1
0
1
0
0.91875
0
0
1
1
1
0
1
0.91250
0
0
1
1
1
0
0
0.90625
0
0
1
1
1
1
1
0.90000
0
0
1
1
1
1
0
0.89375
0
1
0
0
0
0
1
0.88750
0
1
0
0
0
0
0
0.88125
0
1
0
0
0
1
1
0.87500
0
1
0
0
0
1
0
0.86875
0
1
0
0
1
0
1
0.86250
0
1
0
0
1
0
0
0.85625
0
1
0
0
1
1
1
0.85000
0
1
0
0
1
1
0
0.84375
0
1
0
1
0
0
1
0.83750
0
1
0
1
0
0
0
0.83125
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17
NCP5381A
ELECTRICAL CHARACTERISTICS
(0C < TA < 70C; 0C < TJ < 125C; 10.8 V < VCC < 13.2 V; All DAC Codes; CVCC = 0.1 mF, unless otherwise stated)
Parameter
Test Conditions
Min
Typ
Max
Units
--
--
0.5
5.0
8.0
%
mV
mV
VR 11 DAC
System Voltage Accuracy
1.0 V < DAC < 1.6 V
0.8 V < DAC < 1.0 V
0.5 V < DAC < 0.8 V
No--Load Offset Voltage from
Nominal DAC Specification
With CS Input ΔVin = 0 V
--19
mV
Table 2: VR11 VID Codes
VID7
800 mV
VID6
400 mV
VID5
200 mV
VID4
100 mV
VID3
50 mV
VID2
25 mV
VID1
12.5 mV
VID0
6.25 mV
Nominal
DAC
Voltage (V)
HEX
0
0
0
0
0
0
0
0
OFF
00
0
0
0
0
0
0
0
1
OFF
01
0
0
0
0
0
0
1
0
1.60000
02
0
0
0
0
0
0
1
1
1.59375
03
0
0
0
0
0
1
0
0
1.58750
04
0
0
0
0
0
1
0
1
1.58125
05
0
0
0
0
0
1
1
0
1.57500
06
0
0
0
0
0
1
1
1
1.56875
07
0
0
0
0
1
0
0
0
1.56250
08
0
0
0
0
1
0
0
1
1.55625
09
0
0
0
0
1
0
1
0
1.55000
0A
0
0
0
0
1
0
1
1
1.54375
0B
0
0
0
0
1
1
0
0
1.53750
0C
0
0
0
0
1
1
0
1
1.53125
0D
0
0
0
0
1
1
1
0
1.52500
0E
0
0
0
0
1
1
1
1
1.51875
0F
0
0
0
1
0
0
0
0
1.51250
10
0
0
0
1
0
0
0
1
1.50625
11
0
0
0
1
0
0
1
0
1.50000
12
0
0
0
1
0
0
1
1
1.49375
13
0
0
0
1
0
1
0
0
1.48750
14
0
0
0
1
0
1
0
1
1.48125
15
0
0
0
1
0
1
1
0
1.47500
16
0
0
0
1
0
1
1
1
1.46875
17
0
0
0
1
1
0
0
0
1.46250
18
0
0
0
1
1
0
0
1
1.45625
19
0
0
0
1
1
0
1
0
1.45000
1A
0
0
0
1
1
0
1
1
1.44375
1B
0
0
0
1
1
1
0
0
1.43750
1C
0
0
0
1
1
1
0
1
1.43125
1D
0
0
0
1
1
1
1
0
1.42500
1E
0
0
0
1
1
1
1
1
1.41875
1F
0
0
1
0
0
0
0
0
1.41250
20
0
0
1
0
0
0
0
1
1.40625
21
0
0
1
0
0
0
1
0
1.40000
22
0
0
1
0
0
0
1
1
1.39375
23
0
0
1
0
0
1
0
0
1.38750
24
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18
NCP5381A
Table 2: VR11 VID Codes
VID7
800 mV
VID6
400 mV
VID5
200 mV
VID4
100 mV
VID3
50 mV
VID2
25 mV
VID1
12.5 mV
VID0
6.25 mV
Nominal
DAC
Voltage (V)
HEX
0
0
1
0
0
1
0
1
1.38125
25
0
0
1
0
0
1
1
0
1.37500
26
0
0
1
0
0
1
1
1
1.36875
27
0
0
1
0
1
0
0
0
1.36250
28
0
0
1
0
1
0
0
1
1.35625
29
0
0
1
0
1
0
1
0
1.35000
2A
0
0
1
0
1
0
1
1
1.34375
2B
0
0
1
0
1
1
0
0
1.33750
2C
0
0
1
0
1
1
0
1
1.33125
2D
0
0
1
0
1
1
1
0
1.32500
2E
0
0
1
0
1
1
1
1
1.31875
2F
0
0
1
1
0
0
0
0
1.31250
30
0
0
1
1
0
0
0
1
1.30625
31
0
0
1
1
0
0
1
0
1.30000
32
0
0
1
1
0
0
1
1
1.29375
33
0
0
1
1
0
1
0
0
1.28750
34
0
0
1
1
0
1
0
1
1.28125
35
0
0
1
1
0
1
1
0
1.27500
36
0
0
1
1
0
1
1
1
1.26875
37
0
0
1
1
1
0
0
0
1.26250
38
0
0
1
1
1
0
0
1
1.25625
39
0
0
1
1
1
0
1
0
1.25000
3A
0
0
1
1
1
0
1
1
1.24375
3B
0
0
1
1
1
1
0
0
1.23750
3C
0
0
1
1
1
1
0
1
1.23125
3D
0
0
1
1
1
1
1
0
1.22500
3E
0
0
1
1
1
1
1
1
1.21875
3F
0
1
0
0
0
0
0
0
1.21250
40
0
1
0
0
0
0
0
1
1.20625
41
0
1
0
0
0
0
1
0
1.20000
42
0
1
0
0
0
0
1
1
1.19375
43
0
1
0
0
0
1
0
0
1.18750
44
0
1
0
0
0
1
0
1
1.18125
45
0
1
0
0
0
1
1
0
1.17500
46
0
1
0
0
0
1
1
1
1.16875
47
0
1
0
0
1
0
0
0
1.16250
48
0
1
0
0
1
0
0
1
1.15625
49
0
1
0
0
1
0
1
0
1.15000
4A
0
1
0
0
1
0
1
1
1.14375
4B
0
1
0
0
1
1
0
0
1.13750
4C
0
1
0
0
1
1
0
1
1.13125
4D
0
1
0
0
1
1
1
0
1.12500
4E
0
1
0
0
1
1
1
1
1.11875
4F
0
1
0
1
0
0
0
0
1.11250
50
0
1
0
1
0
0
0
1
1.10625
51
0
1
0
1
0
0
1
0
1.10000
52
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19
NCP5381A
Table 2: VR11 VID Codes
VID7
800 mV
VID6
400 mV
VID5
200 mV
VID4
100 mV
VID3
50 mV
VID2
25 mV
VID1
12.5 mV
VID0
6.25 mV
Nominal
DAC
Voltage (V)
HEX
0
1
0
1
0
0
1
1
1.09375
53
0
1
0
1
0
1
0
0
1.08750
54
0
1
0
1
0
1
0
1
1.08125
55
0
1
0
1
0
1
1
0
1.07500
56
0
1
0
1
0
1
1
1
1.06875
57
0
1
0
1
1
0
0
0
1.06250
58
0
1
0
1
1
0
0
1
1.05625
59
0
1
0
1
1
0
1
0
1.05000
5A
0
1
0
1
1
0
1
1
1.04375
5B
0
1
0
1
1
1
0
0
1.03750
5C
0
1
0
1
1
1
0
1
1.03125
5D
0
1
0
1
1
1
1
0
1.02500
5E
0
1
0
1
1
1
1
1
1.01875
5F
0
1
1
0
0
0
0
0
1.01250
60
0
1
1
0
0
0
0
1
1.00625
61
0
1
1
0
0
0
1
0
1.00000
62
0
1
1
0
0
0
1
1
0.99375
63
0
1
1
0
0
1
0
0
0.98750
64
0
1
1
0
0
1
0
1
0.98125
65
0
1
1
0
0
1
1
0
0.97500
66
0
1
1
0
0
1
1
1
0.96875
67
0
1
1
0
1
0
0
0
0.96250
68
0
1
1
0
1
0
0
1
0.95625
69
0
1
1
0
1
0
1
0
0.95000
6A
0
1
1
0
1
0
1
1
0.94375
6B
0
1
1
0
1
1
0
0
0.93750
6C
0
1
1
0
1
1
0
1
0.93125
6D
0
1
1
0
1
1
1
0
0.92500
6E
0
1
1
0
1
1
1
1
0.91875
6F
0
1
1
1
0
0
0
0
0.91250
70
0
1
1
1
0
0
0
1
0.90625
71
0
1
1
1
0
0
1
0
0.90000
72
0
1
1
1
0
0
1
1
0.89375
73
0
1
1
1
0
1
0
0
0.88750
74
0
1
1
1
0
1
0
1
0.88125
75
0
1
1
1
0
1
1
0
0.87500
76
0
1
1
1
0
1
1
1
0.86875
77
0
1
1
1
1
0
0
0
0.86250
78
0
1
1
1
1
0
0
1
0.85625
79
0
1
1
1
1
0
1
0
0.85000
7A
0
1
1
1
1
0
1
1
0.84375
7B
0
1
1
1
1
1
0
0
0.83750
7C
0
1
1
1
1
1
0
1
0.83125
7D
0
1
1
1
1
1
1
0
0.82500
7E
0
1
1
1
1
1
1
1
0.81875
7F
1
0
0
0
0
0
0
0
0.81250
80
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20
NCP5381A
Table 2: VR11 VID Codes
VID7
800 mV
VID6
400 mV
VID5
200 mV
VID4
100 mV
VID3
50 mV
VID2
25 mV
VID1
12.5 mV
VID0
6.25 mV
Nominal
DAC
Voltage (V)
HEX
1
0
0
0
0
0
0
1
0.80625
81
1
0
0
0
0
0
1
0
0.80000
82
1
0
0
0
0
0
1
1
0.79375
83
1
0
0
0
0
1
0
0
0.78750
84
1
0
0
0
0
1
0
1
0.78125
85
1
0
0
0
0
1
1
0
0.77500
86
1
0
0
0
0
1
1
1
0.76875
87
1
0
0
0
1
0
0
0
0.76250
88
1
0
0
0
1
0
0
1
0.75625
89
1
0
0
0
1
0
1
0
0.75000
8A
1
0
0
0
1
0
1
1
0.74375
8B
1
0
0
0
1
1
0
0
0.73750
8C
1
0
0
0
1
1
0
1
0.73125
8D
1
0
0
0
1
1
1
0
0.72500
8E
1
0
0
0
1
1
1
1
0.71875
8F
1
0
0
1
0
0
0
0
0.71250
90
1
0
0
1
0
0
0
1
0.70625
91
1
0
0
1
0
0
1
0
0.70000
92
1
0
0
1
0
0
1
1
0.69375
93
1
0
0
1
0
1
0
0
0.68750
94
1
0
0
1
0
1
0
1
0.68125
95
1
0
0
1
0
1
1
0
0.67500
96
1
0
0
1
0
1
1
1
0.66875
97
1
0
0
1
1
0
0
0
0.66250
98
1
0
0
1
1
0
0
1
0.65625
99
1
0
0
1
1
0
1
0
0.65000
9A
1
0
0
1
1
0
1
1
0.64375
9B
1
0
0
1
1
1
0
0
0.63750
9C
1
0
0
1
1
1
0
1
0.63125
9D
1
0
0
1
1
1
1
0
0.62500
9E
1
0
0
1
1
1
1
1
0.61875
9F
1
0
1
0
0
0
0
0
0.61250
A0
1
0
1
0
0
0
0
1
0.60625
A1
1
0
1
0
0
0
1
0
0.60000
A2
1
0
1
0
0
0
1
1
0.59375
A3
1
0
1
0
0
1
0
0
0.58750
A4
1
0
1
0
0
1
0
1
0.58125
A5
1
0
1
0
0
1
1
0
0.57500
A6
1
0
1
0
0
1
1
1
0.56875
A7
1
0
1
0
1
0
0
0
0.56250
A8
1
0
1
0
1
0
0
1
0.55625
A9
1
0
1
0
1
0
1
0
0.55000
AA
1
0
1
0
1
0
1
1
0.54375
AB
1
0
1
0
1
1
0
0
0.53750
AC
1
0
1
0
1
1
0
1
0.53125
AD
1
0
1
0
1
1
1
0
0.52500
AE
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21
NCP5381A
Table 2: VR11 VID Codes
VID7
800 mV
VID6
400 mV
VID5
200 mV
VID4
100 mV
VID3
50 mV
VID2
25 mV
VID1
12.5 mV
VID0
6.25 mV
Nominal
DAC
Voltage (V)
HEX
1
0
1
0
1
1
1
1
0.51875
AF
1
0
1
1
0
0
0
0
0.51250
B0
1
0
1
1
0
0
0
1
0.50625
B1
1
0
1
1
0
0
1
0
0.50000
B2
1
1
1
1
1
1
1
0
OFF
FE
1
1
1
1
1
1
1
1
OFF
FF
OFF
B3 to FD
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NCP5381A
TYPICAL CHARACTERISTICS
13.6
VCC, UNDERVOLTAGE LOCKOUT
THRESHOLD VOLTAGE (V)
ICC, IC QUIESCENT CURRENT (mA)
10
13.4
13.2
13.0
12.8
0
10
20
30
40
50
60
VCC Increasing Voltage
8
VCC Decreasing Voltage
7
70
0
20
10
30
40
50
60
TA, AMBIENT TEMPERATURE (C)
TA, AMBIENT TEMPERATURE (C)
Figure 5. IC Quiescent Current vs. Ambient
Temperature
Figure 6. VCC Undervoltage Lockout
Threshold Voltage vs. Ambient Temperature
0.0198
0.0196
25C
0.0194
DAC OFFSET
12.6
9
0.0192
0.0190
0.0188
0C
0.0186
0.0184
70C
0.0182
0.0180
0.5 0.6 0.7
0.8 0.9 1.0 1.1
1.2 1.3 1.4
1.5 1.6
VID
Figure 7. Typical DAC Voltage Offset vs.
Temperature
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70
NCP5381A
FUNCTIONAL DESCRIPTION
General
shown in the 4-- phase Applications Schematic. The
following truth table summarizes the modes of operation:
The NCP5381A dual edge modulated multiphase PWM
controller is specifically designed with the necessary
features for a high current VR10 or VR11 CPU power
system. The IC consists of the following blocks: Precision
Programmable DAC, Differential Remote Voltage Sense
Amplifier, High Performance Voltage Error Amplifier,
Differential Current Feedback Amplifiers, Precision
Oscillator and Triangle Wave Generators, and PWM
Comparators. Protection features include Undervoltage
Lockout, Soft-- Start, Overcurrent Protection, Overvoltage
Protection, and Power Good Monitor.
Gate Output Connections
Mode
G1
G2
G3
G4
2--Phase
Normal
OPEN
Normal
OPEN
3--Phase
Normal
Normal
Normal
GND
4--Phase
Normal
Normal
Normal
Normal
These are the only allowable connection schemes to
program the modes of operation.
Remote Output Sensing Amplifier (RSA)
Differential Current Sense Amplifiers
A true differential amplifier allows the NCP5381A to
measure Vcore voltage feedback with respect to the Vcore
ground reference point by connecting the Vcore reference
point to VS+, and the Vcore ground reference point to VS-- .
This configuration keeps ground potential differences
between the local controller ground and the Vcore ground
reference point from affecting regulation of Vcore between
Vcore and Vcore ground reference points. The RSA also
subtracts the DAC (minus VID offset) voltage, thereby
producing an unamplified output error voltage at the
DIFFOUT pin. This output also has a 1.3 V bias voltage to
allow both positive and negative error voltages.
Four differential amplifiers are provided to sense the
output current of each phase. The inputs of each current
sense amplifier must be connected across the current
sensing element of the phase controlled by the
corresponding gate output (G1, G2, G3, or G4). If a phase
is unused, the differential inputs to that phase’s current
sense amplifier must be shorted together and connected
to VCCP as shown in the 2-- and 3-- phase Application
Schematics.
A voltage is generated across the current sense element
(such as an inductor or sense resistor) by the current
flowing in that phase. The output of the current sense
amplifiers are used to control three functions. First, the
output controls the adaptive voltage positioning, where the
output voltage is actively controlled according to the
output current. In this function, all of the current sense
outputs are summed so that the total output current is used
for output voltage positioning. Second, the output signal is
fed to the current limit circuit. This again is the summed
current of all phases in operation. Finally, the individual
phase current is connected to the PWM comparator. In this
way current balance is accomplished.
Precision Programmable DAC
A precision programmable DAC is provided. This DAC
has 0.5% accuracy over the entire operating temperature
range of the part. The DAC can be programmed to support
either VR10 or VR11 specifications. A program selection pin
is provided to accomplish this. This pin also sets the startup
mode of operation. Connect this pin to 1.25 V to select the
VR11 DAC table, and the VR11 startup mode. Connect this
pin to ground to select the VR10 DAC table and the VR11
startup mode. Connect this pin to VREF to select the VR10
DAC table and the VR10 startup mode.
Oscillator and Triangle Wave Generator
A programmable precision oscillator is provided. The
oscillator’s frequency is programmed by the resistance
connected from the ROSC pin to ground. The user will
usually form this resistance from two resistors in order to
create a voltage divider that uses the ROSC output voltage
as the reference for creating the current limit setpoint
voltage. The oscillator frequency range is 100 kHz/phase
to 1.0 MHz/phase. The oscillator generates up to 4 triangle
waveforms (symmetrical rising and falling slopes)
between 1.3 V and 2.3 V. The triangle waves have a phase
delay between them such that for 2-- , 3-- , and 4-- phase
operation the PWM outputs are separated by 180, 120, and
90 angular degrees, respectively.
High Performance Voltage Error Amplifier
The error amplifier is designed to provide high slew rate
and bandwidth. Although not required when operating as
a voltage regulator for VR10 or VR11, a capacitor from
COMP to VFB is required for stable unity gain test
configurations.
Gate Driver Outputs and 2/3/4 Phase Operation
The part can be configured to run in 2-- , 3-- , or 4-- phase
mode. In 2-- phase mode, phases 1 and 3 should be used to
drive the external gate drivers as shown in the 2-- phase
Applications Schematic. In 3-- phase mode, gate output G4
must be grounded as shown in the 3-- phase Applications
Schematic. In 4-- phase mode all 4 gate outputs are used as
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NCP5381A
PWM Comparators with Hysteresis
information exceeds the voltage at the ILIM pin. The
outputs are immediately disabled, the VR_RDY and
DRVON pins are pulled low, and the soft-- start is pulled
low. The outputs will remain disabled until the VCC voltage
is removed and re-- applied, or the ENABLE input is
brought low and then high.
Four PWM comparators receive the error amplifier
output signal at their noninverting input. Each comparator
receives one of the triangle waves offset by 1.3 V at it’s
inverting input. The output of the comparator generates the
PWM outputs G1, G2, G3, and G4.
During steady state operation, the duty cycle will center
on the valley of the triangle waveform, with steady state
duty cycle calculated by Vout/Vin. During a transient event,
both high and low comparator output transitions shift phase
to the points where the error amplifier output intersects the
down and up ramp of the triangle wave.
Overvoltage Protection and Power Good Monitor
An output voltage monitor is incorporated. During
normal operation, if the voltage at the DIFFOUT pin
exceeds 1.3 V, the VR_RDY pin goes low, the DRVON
signal remains high, the PWM outputs are set low. The
outputs will remain disabled until the VCC voltage is
removed and reapplied. During normal operation, if the
output voltage falls more than 300 mV below the DAC
setting, the VR_RDY pin will be set low until the output
rises.
PROTECTION FEATURES
Undervoltage Lockout
An undervoltage lockout (UVLO) senses the VCC input.
During powerup, the input voltage to the controller is
monitored, and the PWM outputs and the soft-- start circuit
are disabled until the input voltage exceeds the threshold
voltage of the UVLO comparator. The UVLO comparator
incorporates hysteresis to avoid chattering, since VCC is
likely to decrease as soon as the converter initiates
soft-- start.
Soft--Start
The
NCP5381A
incorporates
an
externally
programmable soft-- start. The soft-- start circuit works by
controlling the ramp-- up of the DAC voltage during
powerup. The initial soft-- start pin voltage is 0 V. The
soft-- start circuitry clamps the DAC input of the Remote
Sense Amplifier to the SS pin voltage until the SS pin
voltage exceeds the DAC setting minus VID offset. The
soft-- start pin is pulled to 0 V if there is an overcurrent
shutdown, if the ENABLE pin is low, if VCC is below the
UVLO threshold, or if an overvoltage condition exists.
There are two possible soft-- start modes: Legacy VR10
and VR11. VR10 mode simply ramps Vcore from 0 V
directly to the DAC setting at the rate set by the capacitor
connected to the SS pin. The VR11 mode ramps Vcore to
1.1 V at the SS capacitor charge rate, pauses at 1.1 V for
170 ms, reads the VID pins to determine the DAC setting,
then ramps Vcore to the final DAC setting at the
Dynamic VID slew rate of 7.3 mV/ms. Typical VR10 and
VR11 soft-- start sequences are shown in the following
graphs.
Overcurrent Shutdown
A programmable overcurrent function is incorporated
within the IC. A comparator and latch makeup this
function. The inverting input of the comparator is
connected to the ILIM pin. The voltage at this pin sets the
maximum output current the converter can produce. The
ROSC pin provides a convenient and accurate reference
voltage from which a resistor divider can create the
overcurrent setpoint voltage. Although not actually
disabled, tying the ILIM pin directly to the ROSC pin sets
the limit above useful levels – effectively disabling
overcurrent shutdown. The comparator noninverting input
is the summed current information from the current sense
amplifiers. The overcurrent latch is set when the current
2.4
2.2
2.0
VOLTAGE
1.8
VID Setting
1.6
1.4
1.2
1.0
0.8
0.6
Vcore Voltage
SS Pin Voltage
0.4
0.2
0
TIME
0
Figure 8. Typical VR10 Soft--Start Sequence to Vcore = 1.3 V
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NCP5381A
2.4
2.2
2.0
VID Setting
VOLTAGE
1.8
Boot Voltage
1.6
1.4
1.2
1.0
Boot
Dwell Time
0.8
0.6
Vcore Voltage
SS Pin Voltage
0.4
0.2
0
NCP5381A
Internal Dynamic
VID Rate Limit
TIME
0
Figure 9. Typical VR11 Soft--Start Sequence to Vcore = 1.3 V
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26
NCP5381A
APPLICATION INFORMATION
The NCP5381A is a high performance multiphase
controller optimized to meet the Intel VR11 Specifications.
The demo board for the NCP5381A is available by request.
It is configured as a four phase solution with decoupling
designed to provide a 1.0 mΩ load line under a 100 A step
load. A schematic is available upon request from ON
Semiconductor.
16. Start the second ATX supply by turning it on and
setting the PSON DIP switch low. The green VID
lights should light up to match the VTT tool VID
setting.
17. Set the VR_ENABLE DIP switch up to start the
NCP5381A.
18. Check that the output voltage is about 19 mV
below the VID setting.
Startup Procedure
The demo board comes with a Socket 775 and requires
an Intel dynamic load tool (VTT Tool) available through a
third party supplier, Cascade Systems. The web page is
http://www.cascadesystems.net/.
Start by installing the test tool software. It’s best to power
the test tool from a separate ATX power supply. The test
tool should be set to a valid VID code of 0.5 V or above
in-- order for the controller to start. Consult the VTT help
manual for more detailed instructions.
Step Load Testing
The VTT tool is used to generate the high di/dt step load.
Select the dynamic loading option in the VTT test tool
software. Set the desired step load size, frequency, duty,
and slew rate. See Figures 10 and 11.
Startup Sequence
1. Make sure the VTT software is installed.
2. Powerup the PC or Laptop do not start the VTT
software.
3. Insert the VTT Test Tool adapter into the socket
and lock it down.
4. Inset the socket saver pin field into the bottom of
the VTT test tool.
5. Carefully line up the tool with the socket in the
board and press tool into the board.
6. Connect the scope probe, or DMM to the voltage
sense lines on the test tool. When using a scope
probe it is best to isolate the scope from the AC
ground. Make the ground connection on the scope
probe as short as possible.
7. Connect the first ATX supply to the VTT tool.
8. Powerup the first ATX supply to the VTT tool.
9. Start the VTT tool software in VR11 mode with
the current limit set to 150 A.
10. Using the VTT tool software, select a VID code
that is 0.5 V or above.
11. Connect the second ATX supply to the demo
board.
12. Set the VID DIP switches. All the VID switches
should be up or open.
13. Set the VR_ENABLE DIP switch down or
closed.
14. Set the VR10 DIP switch up or open.
15. Set the VID_SEL switch up or open.
Figure 10. Typical Step Load Response
Figure 11. Typical Load Release Event
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NCP5381A
Dynamic VID Testing
The VTT tool provides for VID stepping based on the
Intel Requirements. Select the Dynamic VID option.
Before enabling the test set the lowest VID to 0.5 V or
greater and set the highest VID to a value that is greater than
the lowest VID selection, then enable the test. See Figures
12 through 14.
Design Methodology
Decoupling the VCC Pin on the IC
An RC input filter is required as shown in the VCC pin to
minimize supply noise on the IC. The resistor should be sized
such that it does not generate a large voltage drop between the
12 V supply and the IC. See the schematic values.
Understanding Soft--Start
The controller supports two different startup routines. A
legacy VR10 ramp to the initial VID code, or a VR11 Ramp
to the 1.1 V VID code, with a pause to capture the VID code
then resume ramping to target value based on an internal
slew rate limit. See Figures 15 and 16. The controller is
designed to regulate to the voltage on the SS pin until it
reaches the internal DAC voltage. The soft-- start cap sets
the initial ramp rate using a typical 5.0 mA current. The
typical value to use for the soft-- start cap (SS), is typically
set to 0.01 mF. This results in a ramp time to 1.1 V of 2.2 ms
based on equation 1.
dtss
dvss
1.1 · V
dv
= ss and iss = 5 · mA
dtss
2.2 · ms
Css ≅ iss
Figure 12. 1.6 to 0.5 Dynamic VID Response
Css = 0.01 · mF
Figure 13. Dynamic VID Settling Time Rising
Figure 15. VR11 Startup
Figure 16. VR10 Legacy Startup
Figure 14. Dynamic VID Settling Time Falling
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(eq. 1)
NCP5381A
Programming the Current Limit and the Oscillator Frequency
The demo board is set for an operating frequency of
approximately 300 kHz. The OSC pin provides a 2.0 V
reference voltage which is divided down with a resistor
divider and fed into the current limit pin ILIM. Calculate
the total series resistance to set the frequency and then
calculate the individual values for current limit divider.
The series resistors RLIM1 and RLIM2 sink current to
ground. This current is internally mirrored into a capacitor
to create an oscillator. The period is proportional to the
resistance and frequency is inversely proportional to the
resistance. The resistance may be estimated by equation 2
or 3 depending on the phase count.
9
32.36 kΩ ≅ 10.14 × 10 − 1440
300 · k
(eq. 2)
4 Phase Mode
9
ROSC = 10.14 × 10 − 1440
Frequency
(eq. 3)
3 Phase Mode
9
ROSC = 9.711 × 10 − 1111
Frequency
100
ROSC (kOhms)
90
80
4 Phase Mode
70
3 Phase Mode
60
50
40
30
20
10
0
1000
900
800
700
600
500
400
300
200
100
Frequency (kHz)
Figure 17. ROSC vs. Phase Frequency
The current limit function is based on the total sensed
current of all phases multiplied by a gain of 5.94. DCR
sensed inductor current is function of the winding
temperature. The best approach is to set the maximum
current limit based on the expected average maximum
temperature of the inductor windings.
DCRTmax = DCR25C ·
(1 + 0.00393 · C --1 (TTmax --25 · C))
Calculate the current limit voltage:

VILIMIT ≅ 5.94 · IMIN_OCP · DCRTmax +
DCR50C · Vout
2 · Vin · Fs
 − 0.02

· Vin--Vout − (N--1) · Vout
L
L
Solve for the individual resistors:
RLIM2 =
VILIMIT · ROSC
(eq. 5)
(eq. 6)
RLIM1 = ROSC --RLIM2
2·V
(eq. 4)
Final Equation for the Current Limit Threshold
ILIMIT(Tinductor) ≅

2 · V · RLIM2
RLIM1+RLIM2
 + 0.02
5.94 · (DCR25C · (1 + 0.00393 · C --1(TInductor--25 · C)))
−


Vout
· Vin--Vout − (N--1) · Vout
L
L
2 · Vin · Fs
(eq. 7)
Inductor Selection
When using inductor current sensing it is recommended
that the inductor does not saturate by more than 10% at
maximum load. The inductor also must not go into hard
saturation before current limit trips. The demo board includes
a four phase output filter using the T50--8 core from
Micrometals with 4turns and a DCR target of 0.75 mΩ @
25C. Smaller DCR values can be used, however, current
sharing accuracy and droop accuracy decrease as DCR
decreases. Use the excel spreadsheet for regulation accuracy
calculations for a specific value of DCR.
The inductors on the demo board have a DCR at 25C of
0.75 mΩ. Selecting the closest available values of 16.9 kΩ
for RLIM1 and 15.8 kΩ for RLIM2 yield a nominal
operating frequency of 305 kHz and an approximate
current limit of 180 A at 100C. The total sensed current
can be observed as a scaled voltage at the VDRP pin added
to a positive, no-- load offset of approximately 1.3 V.
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29
NCP5381A
Inductor Current Sense Compensation
The NCP5381A uses the inductor current sensing
method. This method uses an RC filter to cancel out the
inductance of the inductor and recover the voltage that is
the result of the current flowing through the inductor’s
Rsense(T) =
DCR. This is done by matching the RC time constant of the
current sense filter to the L/DCR time constant. The first
cut approach is to use a 0.47 mF capacitor for C and then
solve for R.
L
0.47 · mF · DCR25C · (1 + 0.00393 · C --1 · (T--25 · C))
(eq. 8)
inductor temperature final selection of R is best done
experimentally on the bench by monitoring the Vdroop pin
and performing a step load test on the actual solution.
It is desirable to keep the Rsense resistor value below
1.0 k whenever possible by increasing the capacitor values
in the inductor compensation network. The bias current
flowing out of the current sense pins is approximately
100 nA. This current flows through the current sense
resistor and creates an offset at the capacitor which will
appear as a load current at the Vdroop pin. A 1.0 k resistor
will keep this offset at the droop pin below 2.5 mV.
Figure 18.
Simple Average PSPICE Model
A simple state average model shown in Figure 19 can be
used to determine a stable solution and provide insight into
the control system.
The demoboard inductor measured 350 nH and 0.75 mΩ
at room temp. The actual value used for Rsense was 953 Ω
which matches the equation for Rsense at approximately
50C. Because the inductor value is a function of load and
E1
+
+
-- --
E
0 GAIN = 6
12
-+
-+
VRamp_min
1.3 V
0
-+
L
1
DCR
2
(250e--9/4)
Vin
12
1
4
RDRP
5.11 k
RF
CF
4.3 k
1.5 n
680 p
Unity
Gain
BW = 15 MHz R6
C3
10.6 n
0.75 m
CCer
(22e--6*18)
1Aac
ESRCer
0Adc
(1.5e--3/18)
2
ESLBulk
(3.5e--9/10)
ESLCer
(1.5e--9/18)
1
1
+
--
I1 = 10
I2 = 110
TD = 10u
TR = 50n
TF = 50n
PW = 40u
PER = 80u
+
--
I2
0
CFB1
1E3
RBRD
ESRBulk
(7e--3/10)
2
0
22 p
2
100 p
CBulk
(560e--6*10)
(0.85e--3/4)
Voff
CH
LBRD
RFB1
100
RFB
--+
Voff
Vout
+
--
1k
+
1k
1.3
Voffset
--
0
0
Figure 19.
http://onsemi.com
30
+
VDAC
--
1.25 V
0
NCP5381A
A complex switching model is available by request
which includes a more detailed board parasitic for this
demo board.
bulk capacitors have an ESR of 7.0 mΩ. Thus the bulk ESR
plus the board impedance is 0.7 mΩ + 0.75 mΩ or
1.45 mΩ. The actual output filter impedance does not drop
to 1.0 mΩ until the ceramic breaks in at over 375 kHz. The
controller must provide some loop gain slightly less than
one out to a frequency in excess 300 kHz. At frequencies
below where the bulk capacitance ESR breaks with the
bulk capacitance, the DC-- DC converter must have
sufficiently high gain to control the output impedance
completely. Standard Type-- 3 compensation works well
with the NCP5381A. RFB1 should be kept above 50 Ω for
amplifier stability reasons.
The goal is to compensate the system such that the
resulting gain generates constant output impedance from
DC up to the frequency where the ceramic takes over
holding the impedance below 1.0 mΩ. See the example of
the locations of the poles and zeros that were set to optimize
the model above.
Compensation and Output Filter Design
The values shown on the demo board are a good place to
start for any similar output filter solution. The dynamic
performance can then be adjusted by swapping out various
individual components.
If the required output filter and switching frequency are
significantly different, it’s best to use the available PSPICE
models to design the compensation and output filter from
scratch.
The design target for this demo board was 1.0 mΩ out to
2.0 MHz. The phase switching frequency is currently set to
300 kHz. It can easily be seen that the board impedance of
0.75 mΩ between the load and the bulk capacitance has a
large effect on the output filter. In this case the ten 560 mF
Zout Open Loop
Zout Closed Loop
Open Loop Gain with Current loop Closed
80
Voltage Loop Compensation Gain
1/(2*PI*CFB1*(RFB1+RFB))
60
1/(2*PI*CF*RF)
40
20
1/(2*PI*RF*CF)
RF/RFB1
RF/RFB
Error Amp
Open Loop
Gain
dB
0
1/(2*PI*(RBRD+ESRBulk)*CBulk)
--20
--40
1/(2*PI*SQRT(ESL_Cer*CCer))
1mOhm
--60
--80
--100
100
1/(2*PI*CCer*(RBRD+ESRBulk))
1000
10000
100000
1000000
10000000
Frequency
Figure 20.
By matching the following equations a good set of starting compensation values can be found for a typical mixed bulk
and ceramic capacitor type output filter.
1
1
=
2π · (RBRD + ESRBulk) · CBulk
2π · CF · RF
1
1
=
2π · CCer * (RBRD + ESRBulk)
2π · CFBI · (RFBI + RFB)
http://onsemi.com
31
(eq. 9)
NCP5381A
RFB is always set to 1.0 kΩ and RFB1 is usually set to
100 Ω for maximum phase boost. The value of RF is
typically set to 4.0 kΩ.
RRDP determines the target output impedance by the
basic equation:
Vout = Zout = RFB · DCR · 5.94
RDRP
Iout
RFB · DCR · 5.94
RDRP =
Zout
Droop Injection and Thermal Compensation
The VDRP signal is generated by summing the sensed
output currents for each phase and applying a gain of
approximately six. VDRP is externally summed into the
feedback network by the resistor RDRP. This induces an
offset which is proportional to the output current thereby
forcing the controlled resistive output impedance.
(eq.
10)
The value of the inductor’s DCR varies with temperature
according to the following equation 10:
DCRTmax = DCR25C · (1 + 0.00393 · C --1(TTmax --25 · C))
The system can be thermally compensated to cancel this
effect out to a great degree by adding an NTC (negative
temperature coefficient resistor) in parallel with RFB to
reduce the droop gain as the temperature increases. The
NTC device is nonlinear. Putting a resistor in series with the
(eq. 11)
NTC helps make the device appear more linear with
temperature. The series resistor is split and inserted on both
sides of the NTC to reduce noise injection into the feedback
loop. The recommended value for RISO1 and RISO2 is
approximately 1.0 kΩ.
The output impedance varies with inductor temperature by the equation:
Zout(T) =
RFB · DCR25C · (1 + 0.00393 · C --1(T max --25C)) · 5.94
Rdroop
(eq. 12)
By including the NTC RT2 and the series isolation resistors the new equation becomes:
Zout(T) =
RFB · (RISO1+RT2(T)+RISO2)
RFB+RISO1+RT2(T)+RISO2
· DCR25C · (1 + 0.00393 · C --1(T max --25C)) · 5.94
Rdroop
VRHOT and VRFAN
Thermal monitoring provides two threshold sensitive
comparators for thermal monitoring. The circuit consists of
two comparators that compare the voltage on the NTC pin
to an internal resistor divider connected to VREF. By
powering the external temperature sense divider with
VREF the tolerance of the VREF voltage is canceled out.
The data sheet specifications for the thresholds are shown
as ratios with respect to VREF.
VR_FAN Upper Threshold Ratio = 0.3625
VR_FAN Lower Threshold Ratio = 0.3025
VR_HOT Upper Threshold Ratio = 0.2815
VR_HOT Lower Threshold Ratio = 0.2190
The following equations can be used to find the
temperature trip points.
The typical equation of a NTC is based on a curve fit
equation 13.
1 
2731+ T − 298
RT2(T) = RT225C · e β
(eq. 13)
(eq. 14)
The demo board is populated with a 10 kΩ NTC with a
Beta of 4300. Figure 21 shows the uncompensated and
compensated output impedance versus temperature.
1 
2731+ T − 298
RT1(T) = RT125C · e β
RatioNTC(T) :
Figure 21. Uncompensated and Compensated Output
Impedance vs. Temperature
RNTC2 + RT1(T)
RNTC1 + RNTC2 + RT1(T)
(eq. 15)
(eq. 16)
The demo board contains a 68 K NTC for RT1 with a
Beta of 4750. RNTC1 is populated with 15 kΩ and RNTC2
is populated with a zero ohm resistor. Figure 22 is a plot of
equation 15. The horizontal trip thresholds intersect the
RatioNTC curve.
ON Semiconductor provides an excel spreadsheet to
help with the selection of the NTC. The actual selection of
the NTC will be effected by the location of the output
inductor with respect to the NTC and airflow, and should
be verified with an actual system thermal solution.
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32
NCP5381A
further details. The OVP circuit monitors the output of
DIFFOUT. If the DIFFOUT signal reaches 180 mV above
the nominal 1.3 V offset the OVP will trip. The DIFFOUT
signal is the difference between the output voltage and the
DAC voltage plus the 1.3 V internal offset. This results in
the OVP tracking the DAC voltage even during a dynamic
change in the VID setting during operation.
Gate Driver and MOSFET Selection
ON Semiconductor provides the companion gate driver
IC (NCP3418B). The NCP3418B driver is optimized to
work with a range of MOSFETs commonly used in CPU
applications. The NCP3418B provides special
functionality and is required for the high performance
dynamic VID operation of the part. Contact your local
ON Semiconductor applications engineer for MOSFET
recommendations.
Figure 22.
OVP
The overvoltage protection threshold is not adjustable.
OVP protection is enabled as soon as soft-- start begins and
is disabled when the part is disabled. When OVP is tripped,
the controller commands all four gate drivers to enable
their low side MOSFETs, and VR_RDY transitions low. In
order to recover from an OVP condition, VCC must fall
below the UVLO threshold. See the state diagram for
Board Stack--Up
The demo board follows the recommended Intel
Stack-- up and copper thickness as shown.
Figure 23.
Board Layout
A complete Allegro ATX and BTX demo board layout
file and schematics are available by request at
www.onsemi.com and can be viewed using the Allegro
Free Physical Viewer 15.x from the Cadence website
http://www.cadence.com/.
Close attention should be paid to the routing of the sense
traces and control lines that propagate away from the
controller IC. Routing should follow the demo board
example. For further information or layout review contact
ON Semiconductor.
http://onsemi.com
33
NCP5381A
PACKAGE DIMENSIONS
40 PIN QFN, 7x7
MN SUFFIX
CASE 488AG--01
ISSUE O
A
B
D
PIN ONE
LOCATION
NOTES:
1. DIMENSIONS AND TOLERANCING PER
ASME Y14.5M, 1994.
2. CONTROLLING DIMENSIONS: MILLIMETER.
3. DIMENSION b APPLIES TO PLATED
TERMINAL AND IS MEASURED BETWEEN
0.25 AND 0.30 MM TERMINAL
4. COPLANARITY APPLIES TO THE EXPOSED
PAD AS WELL AS THE TERMINALS.
DIM
A
A1
A3
b
D
D2
E
E2
e
L
k
E
0.15 C
2X
2X
TOP VIEW
0.15 C
MILLIMETERS
MIN
MAX
0.80
1.00
0.00
0.05
0.20 REF
0.18
0.30
7.00 BSC
5.50
5.70
7.00 BSC
5.50
5.70
0.50 BSC
0.30
0.50
0.20
-- -- --
(A3)
0.10 C
A
40 X
0.08 C
SIDE VIEW
A1
SEATING PLANE
C
EXPOSED PAD
D2
L
40 X
11
k
20
40 X
21
10
E2
30
1
40
40 X
b
0.10 C A B
31
e
0.05 C
BOTTOM VIEW
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are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice
to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any
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