PI33xx-x1

Cool-Power®
PI33XX-X1
8V to 36Vin, 15A Cool-Power ZVS Buck Regulator
Description
Features
The PI33XX-X1 is a family of high efficiency, wide
input range DC-DC ZVS-Buck regulators integrating
controller, power switches, and support components
all within a high density System-in-Package (SiP). The
integration of a high performance Zero-Voltage
Switching (ZVS) topology, within the PI33XX-X1 series,
increases point of load performance providing best in
class power efficiency. The PI33XX-X1 requires only
an external inductor and minimal capacitors to form a
complete DC-DC switching mode buck regulator.
Output Voltage
Device
Iout Max
Set
Range
PI3311-X1-LGIZ
1.0V
1.0 to 1.4V
15A
PI3318-X1-LGIZ
1.8V
1.4 to 2.0V
15A
PI3312-X1-LGIZ
2.5V
2.0 to 3.1V
15A
PI3301-X1-LGIZ
3.3V
2.3 to 4.1V
15A
Table 1 - PI33XX-X1-X1 Portfolio.
The ZVS architecture also enables high frequency
operation while minimizing switching losses and
maximizing efficiency. The high switching frequency
operation reduces the size of the external filtering
components, improves power density, and enables
very fast dynamic response to line and load
transients. The PI33XX-X1 series sustains high
switching frequency all the way up to the rated input
voltage without sacrificing efficiency and, with its
20ns minimum on-time, supports large step down
conversions up to 36Vin.













High Efficiency ZVS-Buck Topology
Wide input voltage range of 8V to 36V
Very-Fast transient response
High accuracy pre-trimmed output voltage
User adjustable soft-start & tracking
Power-up into pre-biased load (select versions)
Parallel capable with single wire current sharing
Input Over/Under Voltage Lockout (OVLO/UVLO)
Output Overvoltage Protection (OVP)
Over Temperature Protection (OTP)
Fast and slow current limits
-40°C to 125°C operating range (TJ)
2
Optional I C functionality & programmability:
 Vout margining
 Fault reporting
 Enable and SYNCI pin polarity
 Phase delay (interleaving multiple regulators)
Applications
 High efficiency systems
 Computing, Communications, Industrial,
Automotive Equipment
 High voltage battery operation
Package Information
 10mm x 14mm x 2.6mm LGA SiP
I2C is a trademark of NXP Semiconductors
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®
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Page 1 of 26
PI33XX-X1
Contents
Order Information ...................................................... 3
Application Description .............................................21
Absolute Maximum Ratings ........................................ 4
Output Voltage Trim .......................................... 21
Block Diagram ............................................................. 4
Soft-Start Adjust and Tracking ........................... 22
Pin Description............................................................ 5
Inductor Pairing ................................................. 22
Package Pin-Out.......................................................... 5
Layout Guidelines ......................................................23
PI3311-X1 (1.0 Vout) Electrical Characteristics........... 6
Recommended PCB Footprint and Stencil ................24
PI3318-X1 (1.8 Vout) Electrical Characteristics........... 9
Package Drawings .....................................................25
PI3312-X1 (2.5 Vout) Electrical Characteristics......... 12
Warranty ...................................................................26
PI3301-X1 (3.3 Vout) Electrical Characteristics......... 15
Functional Description .............................................. 18
ENABLE (EN) .......................................................18
Remote Sensing ..................................................18
Switching Frequency Synchronization ................18
Soft-Start ............................................................18
Output Voltage Trim ...........................................18
Output Current Limit Protection ........................19
Input Under-Voltage Lockout .............................19
Input Over Voltage Lockout ................................19
Output Over Voltage Protection.........................19
Over Temperature Protection ............................19
Pulse Skip Mode (PSM) .......................................19
Variable Frequency Operation ...........................20
Parallel Operation ...............................................20
2
I C Interface Operation ...................................... 20
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Page 2 of 26
PI33XX-X1
Order Information
Output Range
Set
Range
Iout
Max
PI3311-01-LGIZ
1.0V
1.0 to 1.4V
15A
10mm x 14mm 123-pin LGA
TRAY
PI3318-01-LGIZ
1.8V
1.4 to 2.0V
15A
10mm x 14mm 123-pin LGA
TRAY
PI3312-01-LGIZ
2.5V
2.0 to 3.1V
15A
10mm x 14mm 123-pin LGA
TRAY
PI3301-01-LGIZ
3.3V
2.3 to 4.1V
15A
10mm x 14mm 123-pin LGA
TRAY
Cool-Power
Package
Transport Media
2
I C Functionality & Programmability
PI3311-21-LGIZ
1.0V
1.0 to 1.4V
15A
10mm x 14mm 123-pin LGA
TRAY
PI3318-21-LGIZ
1.8V
1.4 to 2.0V
15A
10mm x 14mm 123-pin LGA
TRAY
PI3312-21-LGIZ
2.5V
2.0 to 3.1V
15A
10mm x 14mm 123-pin LGA
TRAY
PI3301-21-LGIZ
3.3V
2.3 to 4.1V
15A
10mm x 14mm 123-pin LGA
TRAY
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Page 3 of 26
PI33XX-X1
Absolute Maximum Ratings
VIN
-0.7V to 36V
VS1
-0.7 to 36V, -4V for 5ns
SGND
100mA
PGD, SYNCO, SYNCI, EN, EAO, ADJ, TRK, ADR1, ADR2, SCL, SDA
-0.3V to 5.5V / 5mA
PI3311-X0-LGIZ
VOUT, REM
-0.3V to 5.5V
PI3318-X0-LGIZ
-0.5V to 9V
PI3312-X0-LGIZ
-0.8V to 13V
PI3301-X0-LGIZ
-1.0V to 18V
Storage Temperature
-65°C to 150°C
Operating Junction Temperature
-40°C to 125°C
Soldering Temperature for 20 seconds
245°C
ESD Rating
2kV HBM
Notes: At 25°C ambient temperature. Stresses beyond these limits may cause permanent damage to the device. Operation at these
conditions or conditions beyond those listed in the Electrical Specifications table is not guaranteed. All voltage nodes are referenced to
PGND unless otherwise noted. Test conditions are per the specifications within the individual product electrical characteristics.
Block Diagram
Figure 1: Simplified Block Diagram
2
(I C pins SCL, SDA, ADR0, and ADR1 only active for PI33XX-21 device versions)
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Page 4 of 26
PI33XX-X1
Pin Description
Name
Number
Description
2
SGND
Block 1
Signal ground: Internal logic ground for EA, TRK, SYNCI, SYNCO, ADJ and I C (options)
communication returns. SGND and PGND are star connected within the regulator package.
PGND
Block 2
Power ground: VIN and VOUT power returns
VIN
Block 3
Input voltage: and sense for UVLO, OVLO and feed forward ramp
VOUT
Block 5
Output voltage: and sense for power switches and feed-forward ramp
VS1
Block 4
Switching node: and ZVS sense for power switches
PGD
A1
Parallel Good: Used for parallel timing management intended for lead regulator.
EAO
A2
Error amp output: External connection for additional compensation and current sharing.
EN
A3
Enable Input: Regulator enable control. Asserted high or left floating – regulator enabled;
2
Asserted low, regulator output disabled. Polarity is programmable via I C interface.
REM
A5
Remote Sense: High side connection. Connect to output regulation point.
ADJ
B1
TRK
C1
NC
K3, A4
Adjust input: An external resistor may be connected between ADJ pin and SGND or VOUT to trim
the output voltage up or down.
Soft-start and track input: An external capacitor may be connected between TRK pin and SGND
to decrease the rate of rise during soft-start.
No Connect: Leave pins floating.
Synchronization output: Outputs a low signal for ½ of the minimum period for synchronization of
other converters.
Synchronization input: Synchronize to the falling edge of external clock frequency. SYNCI is a high
impedance digital input node and should always be connected to SGND when not in use.
SYNCO
K4
SYNCI
K5
SDA
D1
Data Line: Connect to SGND for PI33XX-10 and -11. For use with PI33XX-20 and -21 only.
SCL
E1
Clock Line: Connect to SGND for PI33XX-01. For use with PI33XX-21 only.
ADR1
H1
Tri-state Address : No connect for PI33XX-01. For use with PI33XX-21 only.
ADR0
G1
Tri-state Address : No connect for PI33XX-01. For use with PI33XX-21 only.
SYNCI
2
SYNCO
1
NC
Package Pin-Out
3
4
5
6
7
PGND
Block 2
8
9
10
11
SGND K
Block 1
J
12
13
14
VIN
Block 3
Block 1: B2-4, C2-4, D2-3, E2-3, F1-3, G2-3,
H2-3, J1-3, K1-2
ADR1 H
Block 2: A8-10, B8-10, C8-10, D8-10, E4-10,
F4-10, G4-10, H4-10, J4-10, K6-10
ADR0 G
SGND F
SCL E
Block 3: G12-14, H12-14, J12-14, K12-14
SDA D
TRK C
VS1
Block 4
ADJ B
PGD A
REM
NC
EN
EAO
VOUT
Block 5
123-Lead LGA (10mm x 14mm)
Top view
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Block 4: A12-14, B12-14, C12-14, D12-14,
E12-14,
Block 5: A6-7, B6-7, C6-7, D6-7
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07/2013
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Page 5 of 26
PI33XX-X1
PI3311-X1 (1.0 Vout) Electrical Characteristics
Specifications apply for -40C < TJ < 125C, Vin =24V, L1=80nH (Note 1) unless other conditions are noted.
Parameter
Input Specifications
Symbol
Min
Typ
Max
Units
Input Voltage
VIN_DC
8
24
36
V
Input Current
IIN_DC
Input Current At Output Short
(fault condition duty cycle)
740
25
IIN_Short
Input Quiescent Current
IQ_VIN
Input Voltage Slew Rate
VIN_SR
Output Specifications
Output Voltage Total Regulation
Output Voltage Trim Range
Line Regulation
VOUT_DC
VOUT_DC
mA
Conditions
Minimum 1mA load
required
Vin = 24V, TC = 25°C,
Iout=15A
mA
Note 2.
mA
Disabled
Enabled (no load)
1
V/μs
Note 2.
1.013
1.4
Note 2.
2
2.5
∆VOUT(∆VIN)
∆VOUT(∆IOUT)
0.10
V
V
%
0.10
%
@25°C, 0.5A<Iout<15A
Output Voltage Ripple
VOUT_AC
45
mVp-p
Iout=5A, Cout=8x100μF,
20MHz BW Note 4.
Continuous Output Current Range
IOUT_DC
IOUT_CL
0.001
VUVLO_START
VUVLO_STOP
VUVLO_HYS
VOVLO_START
VOVLO_STOP
VOVLO_HYS
7.10
6.80
7.60
7.25
0.35
36.1
37.0
37.6
38.4
0.8
Load Regulation
Current Limit
Protection
VIN UVLO Start Threshold
VIN UVLO Stop Threshold
VIN UVLO Hysteresis
VIN OVLO Start Threshold
VIN OVLO Stop Threshold
VIN OVLO Hysteresis
VIN UVLO/OVLO Fault Delay Time
VIN UVLO/OVLO Response Time
Output Over Voltage Protection
0.987
1.0
15
18.0
tf_DLY
VOVP
TOTP
TOTP_HYS
Note 1: All parameters reflect regulator and inductor system
performance. Measurements were made using a standard PI33XX
evaluation board with 3x4” dimensions and 4 layer, 2oz copper.
Refer to inductor pairing table within Application Description
section for specific inductor manufacturer and value.
Note 2: Regulator is assured to meet performance specifications
by design, test correlation, characterization, and/or statistical
process control.
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130
135
A
Note 3.
@25°C, 8V<Vin<36V
Note 2.
A
8.00
7.60
V
V
V
V
V
V
128
Cycles
500
20
tf
Over-Temperature Fault Threshold
Over-Temperature Restart
Hysteresis
1.0
140
30
Number of the
switching freq cycles
ns
%
Above VOUT
°C
Note 2.
°C
Note 3: Output current capability may be limited and other
performance may vary from noted electrical characteristics when
switching frequency or Vout is modified.
Note 4: Refer to Output Ripple plots.
Note 5: Refer to Load Current vs. Ambient Temperature curves.
Note 6: Refer to Switching Frequency vs. Load current curves.
Rev 1.2
07/2013
®
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Page 6 of 26
PI33XX-X1
PI3311-X1 (1.0 Vout) Electrical Characteristics
Specifications apply for -40C < TJ < 125C, Vin =24V, L1=80nH (Note 1) unless other conditions are noted.
Parameter
Symbol
Timing
Switching Frequency
Fault Restart Delay
Min
Typ
Max
500
30
fS
tFR_DLY
Units
kHz
ms
Conditions
Note 6.
Sync In (SYNCI)
Synchronization Frequency Range
∆fSYNCI
SYNCI Threshold
Sync Out (SYNCO)
VSYNCI
SYNCO High
SYNCO Low
SYNCO Rise Time
VSYNCO_HI
VSYNCO_LO
tSYNCO_RT
SYNCO Fall Time
tSYNCO_FT
50
110
%
Relative to set switching
frequency. Note 3.
2.5
V
Source 1mA
10
V
V
ns
10
ns
20pF load
1.04
V
Internal reference
tracking range.
60
V
mV
4.5
0.5
Sink 1mA
20pF load
Soft Start And Tracking
TRK Active Input Range
VTRK
TRK Max Output Voltage
TRK Disable Threshold
Charge Current (Soft – Start)
Discharge Current (Fault)
Soft-Start Time
Enable
VTRK_MAX
VTRK_OV
ITRK
ITRK_DIS
High Threshold
Low Threshold
Threshold Hysteresis
Enable Pull-Up Voltage
VEN_HI
VEN_LO
VEN_HYS
(floating, unfaulted)
Enable Pull-Down Voltage
(floating, faulted)
Source Current
Sink Current
0
20
-70
tSS
0.9
0.7
100
1.2
40
-50
6.8
2.2
-30
1
0.8
200
1.1
0.9
300
µA
mA
ms
V
V
mV
VEN_PU
2
V
VEN_PD
0
V
IEN_SO
IEN_SK
-50
50
µA
µA
Note 1: All parameters reflect regulator and inductor system
performance. Measurements were made using a standard PI33XX
evaluation board with 3x4” dimensions and 4 layer, 2oz copper.
Refer to inductor pairing table within Application Description
section for specific inductor manufacturer and value.
Note 2: Regulator is assured to meet performance specifications
by design, test correlation, characterization, and/or statistical
process control.
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CTRK = 0uF
Note 3: Output current capability may be limited and other
performance may vary from noted electrical characteristics when
switching frequency or Vout is modified.
Note 4: Refer to Output Ripple plots.
Note 5: Refer to Load Current vs. Ambient Temperature curves.
Note 6: Refer to Switching Frequency vs. Load current curves.
Rev 1.2
07/2013
®
Cool-Power
Page 7 of 26
PI33XX-X1
PI3311-X1 (1.0 Vout) Electrical Characteristics
Efficiency (%)
Efficiency at 25°C
Transient Response: 7.5A to 15A, at 5A/µs
100
95
90
85
80
75
70
65
60
55
50
8Vin
12V in
24V in
36V in
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Load Current (A)
Regulator and inductor performance
331101
Short Circuit Test
24Vin to 1.0Vout, Cout = 8X 100μF Ceramic
Vout (Ch2) = 100mV/Div, Iout (Ch3) = 5A/Div, 200uS/Div
331102
Output Ripple: 24Vin, 1.0Vout at 15A
Vout (Ch2) = 500mV/Div, Iin (Ch4) = 500mA/Div, 2ms/Div
331103
Cout = 8X 100µF Ceramic, Vout = 50mV/Div, 2.0us/Div
331104
Output ripple: 24Vin, 1.0Vout at 7A
Switching Frequency vs. Load Current
600
Frequency (KHz)
500
400
300
200
8Vin
12Vin
24Vin
36Vin
100
2
3
4
5
6
7 8 9 10 11 12 13 14 15
Load Current (A)
331105
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Cout = 8X 100µF Ceramic, Vout = 50mV/Div, 2.0us/Div
Rev 1.2
07/2013
331106
®
Cool-Power
Page 8 of 26
PI33XX-X1
PI3318-X1 (1.8 Vout) Electrical Characteristics
Specifications apply for -40C < TJ < 125C, Vin =24V, L1=125nH (Note 1) unless other conditions are noted.
Parameter
Input Specifications
Symbol
Min
Typ
Max
Units
Input Voltage
VIN_DC
8
24
36
V
Input Current
IIN_DC
Input Current At Output Short
(fault condition duty cycle)
1.25
A
45
Conditions
Iout=15A
mA
Note 2.
mA
Disabled
Enabled (no load)
1
V/μs
Note2.
1.827
2.0
V
Note 2.
Note 3.
∆VOUT(∆IOUT)
0.10
0.10
V
%
%
Output Voltage Ripple
VOUT_AC
30
mVp-p
Continuous Output Current Range
Current Limit
Protection
IOUT_DC
IIN_Short
Input Quiescent Current
IQ_VIN
Input Voltage Slew Rate
VIN_SR
Output Specifications
Output Voltage Total Regulation
VOUT_DC
Output Voltage Trim Range
Line Regulation
Load Regulation
VOUT_DC
2
2.5
1.773
1.4
∆VOUT(∆VIN)
0
VUVLO_START
VUVLO_STOP
VUVLO_HYS
VOVLO_START
VIN OVLO Stop Threshold
VIN OVLO Hysteresis
VOVLO_STOP
VOVLO_HYS
VIN UVLO/OVLO Fault Delay Time
tf_DLY
VIN UVLO/OVLO Response Time
Output Over Voltage Protection
Over-Temperature Fault Threshold
Over-Temperature Restart
Hysteresis
tf
7.10
6.80
7.60
7.25
0.35
36.1
37.0
37.6
38.4
0.8
VOVP
TOTP
TOTP_HYS
Note 1: All parameters reflect regulator and inductor system
performance. Measurements were made using a standard PI33XX
evaluation board with 3x4” dimensions and 4 layer, 2oz copper.
Refer to inductor pairing table within Application Description
section for specific inductor manufacturer and value.
Note 2: Regulator is assured to meet performance specifications
by design, test correlation, characterization, and/or statistical
process control.
vicorpower.com
800 735.6200
15
A
A
8.00
7.60
V
V
V
V
18.0
IOUT_CL
VIN UVLO Start Threshold
VIN UVLO Stop Threshold
VIN UVLO Hysteresis
VIN OVLO Start Threshold
1.8
130
500
20
135
@25°C, 8V<Vin<36V
@25°C, 0.5A<Iout<15A
Iout=5A, Cout=8x100μF,
20MHz BW Note 4.
Note 2.
V
V
128
Cycles
140
ns
%
°C
30
Number of the
switching freq cycles
Above VOUT
Note 2.
°C
Note 3: Output current capability may be limited and other
performance may vary from noted electrical characteristics when
switching frequency or Vout is modified.
Note 4: Refer to Output Ripple plots.
Note 5: Refer to Load Current vs. Ambient Temperature curves.
Note 6: Refer to Switching Frequency vs. Load current curves.
Rev 1.2
07/2013
®
Cool-Power
Page 9 of 26
PI33XX-X1
PI3318-X1 (1.8 Vout) Electrical Characteristics
Specifications apply for -40C < TJ < 125C, Vin =24V, L1=125nH (Note 1) unless other conditions are noted.
Parameter
Symbol
Timing
Switching Frequency
Fault Restart Delay
Min
Typ
Max
550
30
fS
tFR_DLY
Units
kHz
ms
Conditions
Note 6.
Sync In (SYNCI)
Synchronization Frequency Range
∆fSYNCI
SYNCI Threshold
Sync Out (SYNCO)
VSYNCI
SYNCO High
SYNCO Low
SYNCO Rise Time
VSYNCO_HI
VSYNCO_LO
tSYNCO_RT
SYNCO Fall Time
tSYNCO_FT
50
110
%
Relative to set switching
frequency. Note 3.
2.5
V
Source 1mA
10
V
V
ns
10
ns
20pF load
1.04
V
Internal reference
tracking range.
60
V
mV
4.5
0.5
Sink 1mA
20pF load
Soft Start And Tracking
TRK Active Input Range
VTRK
TRK Max Output Voltage
TRK Disable Threshold
Charge Current (Soft – Start)
Discharge Current (Fault)
Soft-Start Time
Enable
VTRK_MAX
VTRK_OV
ITRK
ITRK_DIS
High Threshold
Low Threshold
Threshold Hysteresis
Enable Pull-Up Voltage
VEN_HI
VEN_LO
VEN_HYS
(floating, unfaulted)
Enable Pull-Down Voltage
(floating, faulted)
Source Current
Sink Current
0
20
-70
tSS
0.9
0.7
100
1.2
40
-50
6.8
2.2
-30
1
0.8
200
1.1
0.9
300
µA
mA
ms
V
V
mV
VEN_PU
2
V
VEN_PD
0
V
IEN_SO
IEN_SK
-50
50
µA
µA
Note 1: All parameters reflect regulator and inductor system
performance. Measurements were made using a standard PI33XX
evaluation board with 3x4” dimensions and 4 layer, 2oz copper.
Refer to inductor pairing table within Application Description
section for specific inductor manufacturer and value.
Note 2: Regulator is assured to meet performance specifications
by design, test correlation, characterization, and/or statistical
process control.
vicorpower.com
800 735.6200
CTRK = 0uF
Note 3: Output current capability may be limited and other
performance may vary from noted electrical characteristics when
switching frequency or Vout is modified.
Note 4: Refer to Output Ripple plots.
Note 5: Refer to Load Current vs. Ambient Temperature curves.
Note 6: Refer to Switching Frequency vs. Load current curves.
Rev 1.2
07/2013
®
Cool-Power
Page 10 of 26
PI33XX-X1
PI3318-X1 (1.8 Vout) Electrical Characteristics
Efficiency(%)
Efficiency at 25°C
Transient Response: 7A to 15A, at 5A/µs
100
95
90
85
80
75
70
65
60
55
50
8Vin
12Vin
24Vin
36Vin
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Load Current (A)
Regulator and inductor performance
331801
24Vin to 1.8Vout, Cout = 8X 100µF Ceramic
Vout (Ch3) = 100mV/Div, Iin (Ch4) = 10A/Div, 80us/Div
Short Circuit Test
331802
Output Ripple: 24Vin, 1.8Vout at 15A
Vout (Ch3) = 500mV/Div, Iin (Ch2) = 1A/Div, 1ms/Div
331803
Switching Frequency vs. Load Current
Cout = 8X 100µF Ceramic, Vout = 20mV/Div, 2.0us/Div
331804
Output ripple: 24Vin, 1.8Vout at 7.5A
Switching Frequency(kHz)
600
500
400
300
200
100
8Vin
12Vin
24Vin
36Vin
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Load Current(A)
Cout = 8X 100µF Ceramic, Vout = 20mV/Div, 2.0us/Div
331805
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07/2013
331806
®
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Page 11 of 26
PI33XX-X1
PI3312-X1 (2.5 Vout) Electrical Characteristics
Specifications apply for -40C < TJ < 125C, Vin =24V, L1=125nH (Note 1) unless other conditions are noted.
Parameter
Input Specifications
Symbol
Min
Typ
Max
Units
Input Voltage
VIN_DC
8
24
36
V
Note 7.
Input Current
IIN_DC
A
Vin = 24V, TC = 25°C,
Iout=15A
Input Current At Output Short
(fault condition duty cycle)
1.7
60
IIN_Short
Input Quiescent Current
IQ_VIN
Input Voltage Slew Rate
VIN_SR
Output Specifications
Output Voltage Total Regulation
Output Voltage Trim Range
Line Regulation
Load Regulation
VOUT_DC
VOUT_DC
mA
Note 2.
mA
Disabled
Enabled (no load)
1
V/μs
Note 2.
2.535
3.1
V
V
%
%
Note 2.
2
2.5
2.465
2.0
∆VOUT (∆VIN)
∆VOUT (∆IOUT)
2.5
2.5
0.10
0.10
Output Voltage Ripple
VOUT_AC
28
Continuous Output Current Range
Current Limit
IOUT_DC
IOUT_CL
0
VIN UVLO Start Threshold
VUVLO_START
7.10
VIN UVLO Stop Threshold
VIN UVLO Hysteresis
VIN OVLO Start Threshold
VIN OVLO Stop Threshold
VIN OVLO Hysteresis
VUVLO_STOP
VUVLO_HYS
VOVLO_START
VOVLO_STOP
VOVLO_HYS
Conditions
mVp-p
15
A
A
7.60
8.00
V
6.80
7.25
0.35
7.60
36.1
37.0
37.6
38.4
0.8
V
V
V
V
V
128
Cycles
140
ns
%
°C
18.0
Note 3. Note 7.
@25°C, 8V<Vin<36V
@25°C, 0.5A<Iout<15A
Iout=5A, Cout=8x100μF,
20MHz BW Note 4.
Note 2. Note 7.
Protection
VIN UVLO/OVLO Fault Delay Time
tf_DLY
VIN UVLO/OVLO Response Time
Output Over Voltage Protection
Over-Temperature Fault Threshold
Over-Temperature Restart
Hysteresis
tf
VOVP
TOTP
TOTP_HYS
Note 1: All parameters reflect regulator and inductor system
performance. Measurements were made using a standard PI33XX
evaluation board with 3x4” dimensions and 4 layer, 2oz copper.
Refer to inductor pairing table within Application Description
section for specific inductor manufacturer and value.
Note 2: Regulator is assured to meet performance specifications
by design, test correlation, characterization, and/or statistical
process control.
vicorpower.com
800 735.6200
130
500
20
135
30
Number of the
switching freq cycles
Above VOUT
Note 2.
°C
Note 3: Output current capability may be limited and other
performance may vary from noted electrical characteristics when
switching frequency or Vout is modified.
Note 4: Refer to Output Ripple plots.
Note 5: Refer to Load Current vs. Ambient Temperature curves.
Note 6: Refer to Switching Frequency vs. Load current curves.
Note 7: Minimum 5V between Vin-Vout must be maintained or a
minimum load of 1mA required.
Rev 1.2
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Page 12 of 26
PI33XX-X1
PI3312-X1 (2.5 Vout) Electrical Characteristics
Specifications apply for -40C < TJ < 125C, Vin =24V, L1=125nH (Note 1) unless other conditions are noted.
Parameter
Symbol
Timing
Switching Frequency
Fault Restart Delay
Min
Typ
Max
650
30
fS
tFR_DLY
Units
kHz
ms
Conditions
Note 6.
Sync In (SYNCI)
Synchronization Frequency Range
∆fSYNCI
SYNCI Threshold
Sync Out (SYNCO)
VSYNCI
SYNCO High
SYNCO Low
SYNCO Rise Time
VSYNCO_HI
VSYNCO_LO
tSYNCO_RT
SYNCO Fall Time
tSYNCO_FT
50
110
%
Relative to set switching
frequency. Note 3.
2.5
V
Source 1mA
10
V
V
ns
10
ns
20pF load
1.04
V
Internal reference
tracking range.
60
-30
V
mV
µA
mA
4.5
0.5
Sink 1mA
20pF load
Soft Start And Tracking
0
TRK Active Input Range
VTRK
TRK Max Output Voltage
VTRK_MAX
TRK Disable Threshold
Charge Current (Soft – Start)
Discharge Current (Fault)
VTRK_OV
ITRK
ITRK_DIS
tSS
20
-70
High Threshold
VEN_HI
0.9
1
1.1
V
Low Threshold
Threshold Hysteresis
Enable Pull-Up Voltage
VEN_LO
VEN_HYS
0.7
100
0.8
200
0.9
300
V
mV
Soft-Start Time
Enable
(floating, unfaulted)
Enable Pull-Down Voltage
(floating, faulted)
Source Current
Sink Current
1.2
40
-50
6.8
2.2
ms
VEN_PU
2
V
VEN_PD
0
V
IEN_SO
IEN_SK
-50
50
µA
µA
Note 1: All parameters reflect regulator and inductor system
performance. Measurements were made using a standard PI33XX
evaluation board with 3x4” dimensions and 4 layer, 2oz copper.
Refer to inductor pairing table within Application Description
section for specific inductor manufacturer and value.
Note 2: Regulator is assured to meet performance specifications
by design, test correlation, characterization, and/or statistical
process control.
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CTRK = 0uF
Note 3: Output current capability may be limited and other
performance may vary from noted electrical characteristics when
switching frequency or Vout is modified.
Note 4: Refer to Output Ripple plots.
Note 5: Refer to Load Current vs. Ambient Temperature curves.
Note 6: Refer to Switching Frequency vs. Load current curves.
Note 7: Minimum 5V between Vin-Vout must be maintained or a
minimum load of 1mA required.
Rev 1.2
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Page 13 of 26
PI33XX-X1
PI3312-X1 (2.5 Vout) Electrical Characteristics
Efficiency (%)
Efficiency at 25°C
Transient Response: 7.5A to 15A, at 5A/µs
100
95
90
85
80
75
70
65
60
55
50
8Vin
12Vin
24Vin
36Vin
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Load Current (A)
Regulator and inductor performance
331201
24Vin to 2.5Vout, Cout = 8 x 100µF Ceramic
Vout (Ch1) = 200mV/Div, Iout (Ch4) = 5A/Div, 200us/Div
331202
Output Ripple: 24Vin, 2.5Vout at 15A
Short Circuit
Vout (Ch1) = 1V/Div, Iin (Ch4) = 1A/Div, 800us/Div
331203
Vout = 50mV/Div, 4.0us/Div, Cout = 8 x 100µF Ceramic
331204
Output Ripple: 24Vin, 2.5Vout at 7.5A
Switching Frequency vs. Load Current
Switching Frequency (kHz)
700
600
500
400
300
200
100
8Vin
12Vin
24Vin
36Vin
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Load Current (A)
331205
Vout = 50mV/Div, 4.0us/Div, Cout = 8 x 100µF Ceramic
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PI33XX-X1
PI3301-X1 (3.3 Vout) Electrical Characteristics
Specifications apply for -40C < TJ < 125C, Vin =24V, L1=155nH (Note 1) unless other conditions are noted.
Parameter
Input Specifications
Symbol
Min
Typ
Max
Units
Input Voltage
VIN_DC
8
24
36
V
Note 7.
Input Current
IIN_DC
A
Vin = 24V, TC = 25°C,
Iout=15A
Input Current At Output Short
(fault condition duty cycle)
2.25
75
IIN_Short
Input Quiescent Current
IQ_VIN
Input Voltage Slew Rate
VIN_SR
Output Specifications
Output Voltage Total Regulation
Output Voltage Trim Range
Line Regulation
Load Regulation
VOUT_DC
VOUT_DC
mA
Note 2.
mA
Disabled
Enabled (no load)
1
V/μs
Note 2.
3.36
4.1
V
V
%
%
Note 2.
2
2.5
3.25
2.3
∆VOUT(∆VIN)
∆VOUT(∆IOUT)
3.30
3.3
0.10
0.10
Output Voltage Ripple
VOUT_AC
37.5
Continuous Output Current Range
Current Limit
IOUT_DC
IOUT_CL
0
VIN UVLO Start Threshold
VUVLO_START
7.10
VIN UVLO Stop Threshold
VIN UVLO Hysteresis
VIN OVLO Start Threshold
VIN OVLO Stop Threshold
VIN OVLO Hysteresis
VUVLO_STOP
VUVLO_HYS
VOVLO_START
VOVLO_STOP
VOVLO_HYS
Conditions
mVp-p
15
A
A
7.60
8.00
V
6.80
7.25
0.35
7.60
36.1
37.0
37.6
38.4
0.8
V
V
V
V
V
128
Cycles
140
ns
%
°C
18.0
Note 3. Note 7.
@25°C, 8<Vin<36V
@25°C, 0.5A<Iout<15A
Iout=5A, Cout=8x100μF,
20MHz BW Note 4.
Note 2. Note 7.
Protection
VIN UVLO/OVLO Fault Delay Time
tf_DLY
VIN UVLO/OVLO Response Time
Output Over Voltage Protection
Over-Temperature Fault Threshold
Over-Temperature Restart
Hysteresis
tf
VOVP
TOTP
TOTP_HYS
Note 1: All parameters reflect regulator and inductor system
performance. Measurements were made using a standard PI33XX
evaluation board with 3x4” dimensions and 4 layer, 2oz copper.
Refer to inductor pairing table within Application Description
section for specific inductor manufacturer and value.
Note 2: Regulator is assured to meet performance specifications
by design, test correlation, characterization, and/or statistical
process control.
vicorpower.com
800 735.6200
130
500
20
135
30
Number of the
switching freq cycles
Above VOUT
Note 2.
°C
Note 3: Output current capability may be limited and other
performance may vary from noted electrical characteristics when
switching frequency or Vout is modified.
Note 4: Refer to Output Ripple plots.
Note 5: Refer to Load Current vs. Ambient Temperature curves.
Note 6: Refer to Switching Frequency vs. Load current curves.
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Page 15 of 26
PI33XX-X1
PI3301-X1 (3.3 Vout) Electrical Characteristics
Specifications apply for -40C < TJ < 125C, Vin =24V, L1=155nH (Note 1) unless other conditions are noted.
Parameter
Symbol
Timing
Switching Frequency
Fault Restart Delay
Min
Typ
Max
650
30
fS
tFR_DLY
Units
kHz
ms
Conditions
Note 6.
Sync In (SYNCI)
Synchronization Frequency Range
∆fSYNCI
SYNCI Threshold
Sync Out (SYNCO)
VSYNCI
SYNCO High
SYNCO Low
SYNCO Rise Time
VSYNCO_HI
VSYNCO_LO
tSYNCO_RT
SYNCO Fall Time
tSYNCO_FT
50
110
%
Relative to set switching
frequency. Note 3.
2.5
V
Source 1mA
10
V
V
ns
10
ns
20pF load
1.04
V
Internal reference
tracking range.
60
-30
V
mV
µA
mA
4.5
0.5
Sink 1mA
20pF load
Soft Start And Tracking
TRK Active Input Range
TRK Max Output Voltage
TRK Disable Threshold
Charge Current (Soft – Start)
Discharge Current (Fault)
Soft-Start Time
Enable
High Threshold
Low Threshold
Threshold Hysteresis
Enable Pull-Up Voltage
(floating, unfaulted)
Enable Pull-Down Voltage
(floating, faulted)
Source Current
Sink Current
VTRK
VTRK_MAX
VTRK_OV
ITRK
ITRK_DIS
tSS
VEN_HI
VEN_LO
VEN_HYS
0
20
-70
1.2
40
-50
6.8
2.2
0.9
0.7
100
1
0.8
200
ms
1.1
0.9
300
V
V
mV
VEN_PU
2
V
VEN_PD
0
V
IEN_SO
IEN_SK
-50
50
µA
µA
Note 1: All parameters reflect regulator and inductor system
performance. Measurements were made using a standard PI33XXX1 evaluation board with 3x4” dimensions and 4 layer, 2oz
copper. Refer to inductor pairing table within Application
Description section for specific inductor manufacturer and value.
Note 2: Regulator is assured to meet performance specifications
by design, test correlation, characterization, and/or statistical
process control.
vicorpower.com
800 735.6200
CTRK = 0uF
Note 3: Output current capability may be limited and other
performance may vary from noted electrical characteristics when
switching frequency or Vout is modified.
Note 4: Refer to Output Ripple plots.
Note 5: Refer to Load Current vs. Ambient Temperature curves.
Note 6: Refer to Switching Frequency vs. Load current curves.
Note 7: Minimum 5V between Vin-Vout must be maintained or a
minimum load of 1mA required.
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Page 16 of 26
PI33XX-X1
PI3301-X1 (3.3 Vout) Electrical Characteristics
Efficiency (%)
Efficiency at 25°C
Transient Response: 7.5 to 15A, at 5A/µs
100
95
90
85
80
75
70
65
60
55
50
8Vin
12Vin
24Vin
36Vin
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Load Current (A)
Regulator and inductor performance
330101
24Vin to 3.3Vout, Cout = 8 x 100µF Ceramic
Vout (Ch1) = 200mV/Div, Iout (Ch4) = 5A/Div, 200us/Div
330102
Output Ripple: 24Vin, 3.3Vout at 15A
Short Circuit
Vout (Ch1) = 1V/Div, Iout (Ch4) = 1A/Div, 800us/Div
330103
Vout = 50mV/Div, 2.0us/Div, Cout = 8 x 100µF Ceramic
330104
Output Ripple: 24Vin, 3.3Vout at 7.5A
Switching Frequency vs. Load Current
Swicthing Frequency (kHz)
800
700
600
500
400
300
200
100
8Vin
12Vin
24Vin
36Vin
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Load Current (A)
330105
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PI33XX-X1
Functional Description
The PI33XX-X1 is a family of highly integrated ZVSBuck regulators. The PI33XX-X1 has a set output
voltage that is trimmable within a prescribed range
shown in Table 1. Performance and maximum
output current are characterized with a specific
external power inductor (see Table 5).
L1
Vin
Vin
Cin
PGND
Vout
VS1
PI33XX
Vout
Cout
REM
SYNCI
TRK
ADJ
EN
EAO
SGND
SYNCO
Figure 2 - ZVS-Buck with required components
For basic operation, Figure 2 shows the connections
and components required. No additional design or
settings are required.
ENABLE (EN)
EN is the enable pin of the converter. The EN Pin is
referenced to SGND and permits the user to turn the
converter on or off. The EN default polarity is a
positive logic assertion. If the EN pin is left floating
or asserted high, the converter output is enabled.
Pulling EN pin below 0.8 Vdc with respect to SGND
will disable the regulator output.
The EN input polarity can be programmed (PI33XX2
21 device versions only) via the I C data bus. When
the EN pin polarity is programmed for negative logic
assertion; and if the EN pin is left floating, the
regulator output is enabled. Pulling the EN pin above
1.0 Vdc with respect to SGND, will disable the
regulator output.
Remote Sensing
An internal 100Ω resistor is connected between REM
pin and VOUT pin to provide regulation when the
REM connection is broken. Referring to Figure 2, it is
important to note that L1 and Cout are the output
filter and the local sense point for the power supply
output. As such, the REM pin should be connected
at Cout as the default local sense connection unless
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remote sensing to compensate additional
distribution losses in the system. The REM pin
should not be left floating.
Switching Frequency Synchronization
The SYNCI input allows the user to synchronize the
controller switching frequency by an external clock
referenced to SGND.
The external clock can
synchronize the unit between 50% and 110% of the
preset switching frequency (fS). For PI33XX-21 device
versions only, the phase delay can be programmed
via I2C bus with respect to the clock
applied at SYNCI pin. Phase delay allows PI33XX-X1
regulators to be paralleled and operate in an
interleaving mode.
The PI33XX-X1 default for SYNCI is to sync with
respect to the falling edge of the applied clock
providing 180° phase shift from SYNCO. This allows
for the paralleling of two PI33XX-X1 devices without
the need for further user programming or external
sync clock circuitry. The user can change the SYNCI
polarity to sync with the external clock rising edge
2
via the I C data bus (PI33XX-21 device versions only).
When using the internal oscillator, the SYNCO pin
provides a 5V clock that can be used to sync other
regulators. Therefore, one PI33XX-X1 can act as the
lead regulator and have additional PI33XX-X1s
running in parallel and interleaved.
Soft-Start
The PI33XX-X1 includes an internal soft-start
capacitor to ramp the output voltage in 2ms from 0V
to full output voltage. Connecting an external
capacitor from the TRK pin to SGND will increase the
start-up ramp period. See, “Soft Start Adjustment
and Track,” in the Applications Description section
for more details.
Output Voltage Trim
The PI33XX-X1 output voltage can be trimmed up
from the preset output by connecting a resistor from
ADJ pin to SGND and can be trimmed down by
connecting a resistor from ADJ pin to VOUT. The
Table 2 defines the voltage ranges for the PI33XX-X1
family.
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Page 18 of 26
PI33XX-X1
Input Over Voltage Lockout
Device
PI3311-X1-LGIZ
PI3318-X1-LGIZ
PI3312-X1-LGIZ
PI3301-X1-LGIZ
Output Voltage
Set
1.0V
1.8V
2.5V
3.3V
Range
1.0 to 1.4V
1.4 to 2.0V
2.0 to 3.1V
2.3 to 4.1V
Table 2 - PI33XX-X1 family output voltage ranges.
.
If VIN exceeds the input Over Voltage Lockout
(OVLO) threshold (VOVLO), while the regulator is
running, the PI33XX-X1 will complete the current
cycle and stop switching. The system will resume
operation after the Fault Restart Delay. The OVLO
fault is stored in a Fault Register and can be read and
cleared (PI33XX-21 device versions only) via I2C data
bus.
Output Current Limit Protection
Output Over Voltage Protection
PI33XX-X1 has two methods implemented to protect
from output short or over current condition.
The PI33XX-X1 family is equipped with output Over
Voltage Protection (OVP) to prevent damage to
input voltage sensitive devices. If the output voltage
exceeds 20% of its set regulated value, the regulator
will complete the current cycle, stop switching and
issue an OVP fault. The system will resume
operation once the output voltage falls below the
OVP threshold and after Fault Restart Delay. The
OVP fault is stored in a Fault Register and can be
read and cleared (PI33XX-21 device versions only) via
2
I C data bus.
Slow Current Limit protection: prevents the output
load from sourcing current higher than the
regulator’s maximum rated current. If the output
current exceeds the Current Limit (IOUT_CL) for
1024us, a slow current limit fault is initiated and the
regulator is shutdown which eliminates output
current flow. After Fault Restart Delay (tFR_DLY), a
soft-start cycle is initiated. This restart cycle will be
repeated indefinitely until the excessive load is
removed.
Over Temperature Protection
Both the Fast and Slow current limit faults are stored
in a Fault Register and can be read and cleared
(PI33XX-21 device versions only) via I2C data bus.
The internal package temperature is monitored to
prevent internal components from reaching their
thermal maximum.
If the Over Temperature
Protection Threshold (OTP) is exceeded (TOTP), the
regulator will complete the current switching cycle,
enter a low power mode, set a fault flag, and will
soft-start when the internal temperature falls below
Over-Temperature Restart Hysteresis (TOTP_HYS). The
OTP fault is stored in a Fault Register and can be
read and cleared (PI33XX-21 device versions only) via
2
I C data bus.
Input Under-Voltage Lockout
Pulse Skip Mode (PSM)
If VIN falls below the input Under Voltage Lockout
(UVLO) threshold, the regulator will enter a low
power state and initiate a fault. The system will
restart once the input voltage is reestablished and
after the Fault Restart Delay. A UVLO fault is stored
in a Fault Register and can be read and cleared
2
(PI33XX-21 device versions only) via I C data bus.
PI33XX-X1 features a PSM to achieve high efficiency
at light loads. The regulators are setup to skip pulses
if EAO falls below a PSM threshold. Depending on
conditions and component values, this may result in
single pulses or several consecutive pulses followed
by skipped pulses. Skipping cycles significantly
reduces gate drive power and improves light load
efficiency. The regulator will leave PSM once the
EAO rises above the Skip Mode threshold.
Fast Current Limit protection: PI33XX-X1 monitors
the regulator inductor current pulse-by-pulse to
prevent the output from supplying very high current
due to a sudden low impedance short. If the
regulator senses a high inductor current pulse, it will
initiate a fault and stop switching until Fault Restart
Delay ends and then initiate a soft-start cycle.
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PI33XX-X1
Variable Frequency Operation
Each PI33XX-X1 is preprogrammed to a base
operating frequency, with respect to the power
stage inductor (see Table 5), to operate at peak
efficiency across line and load variations. At low line
and high load applications, the base frequency will
decrease to accommodate these extreme operating
ranges.
By stretching the frequency, the ZVS
operation is preserved throughout the total input
line voltage range therefore maintaining optimum
efficiency.
Parallel Operation
Paralleling modules can be used to increase the
output current capability of a single power rail and
reduce output voltage ripple.
L1
Vin
Vin
VS1
Vout
Vout
Cin
Cout
PGND
R1
SYNCO(#2)
PGD
EN(#2)
SYNCO
EN
EAO(#2)
EAO
TRK(#2)
TRK
SGND
L1
Vin
Vin
Cout
PGND
SYNCO(#1)
To R1
EN(#1)
Also, the PI33XX-21 devices allow for dynamic Vout
margining via I2C that is useful during development
(settings stored in volatile memory only and not
retained by the device). The PI33XX-21 also have the
option for fault telemetry including:
ZVS Buck
PGD
(#2) REM
SYNCI
SYNCO
EN
EAO(#1)
EAO
TRK(#1)
TRK
I2C Interface Operation
VS1
Vout
Cin
Multi-phasing three regulators is possible (PI33XX-21
only) with no change to the basic single-phase
design. For more information about how to program
phase delays within the regulator, please refer to
Picor application note PI33XX-2X Multi-Phase Design
Guide.
PI33XX-21 devices provide an I2C digital interface
that enables the user to program the EN pin polarity
(from high to low assertion) and switching frequency
synchronization phase/delay. These are one time
programmable options to the device.
ZVS Buck
(#1) REM
SYNCI
SYNCI(#2)
lead regulator’s SYNCI (#1) pin, as shown in Figure 3.
In this configuration, at system soft-start, the PGD
pin pulls SYNCI low forcing the lead regulator to
initialize the open-loop startup synchronization.
Once the regulators reach regulation, SYNCI is
released and the system is now synchronized in a
closed-loop configuration which allows the system to
adjust, on the fly, when any of the individual
regulators begin to enter variable frequency mode in
the loop.
SGND
Figure 3 - PI33XX-X1 parallel operation
By connecting the EAO pins and SGND pins of each
module together the units will share the current
equally. When the TRK pins of each unit are
connected together, the units will track each other
during soft-start and all unit EN pins have to be
released to allow the units to start (See Figure 3).
Also, any fault event in any regulator will disable the
other regulators. The two regulators will be out of
phase with each other reducing output ripple (refer
to Switching Frequency Synchronization).





Over temperature protection
Fast/Slow current limit
Output voltage high
Input overvoltage
Input undervoltage
2
For more information about how to utilize the I C
interface please refer to Picor application note
2
PI33XX-2X I C Digital Interface Guide.
To provide synchronization between regulators over
the entire operational frequency range, the Parallel
Good (PGD) pin must be connected to the lead
regulator’s (#1) SYNCI pin and a 2.5kΩ Resistor, R1,
must be placed between SYNCO (#2) return and the
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PI33XX-X1
Application Description
Output Voltage Trim
The PI33XX-X1 family of Buck Regulators provides
four common output voltages: 1.0V, 1.8V, 2.5V, and
3.3V. A post-package trim step is implemented to
offset any resistor divider network errors ensuring
maximum output accuracy. With a single resistor
connected from the ADJ pin to SGND or REM, each
device’s output can be varied above or below the
nominal set voltage (with the exception of the
PI3311-X1 which can only be above the set voltage
of 1V).
Output Voltage
Device
PI3311-X1-LGIZ
PI3318-X1-LGIZ
PI3312-X1-LGIZ
PI3301-X1-LGIZ
Set
Range
1.0V
1.8V
2.5V
3.3V
1.0 to 1.4V
1.4 to 2.0V
2.0 to 3.1V
2.3 to 4.1V
Device
R1
R2
PI3311-X1-LGIZ
PI3318-X1-LGIZ
PI3312-X1-LGIZ
PI3301-X1-LGIZ
1k
0.806k
1.5k
2.61k
Open
1.0k
1.0k
1.13k
Table 4 - PI33XX-X1 Internal divider values
By choosing an output voltage value within the
ranges stated in Table 3, VOUT can simply be
adjusted up or down by selecting the proper R_high
or R_low value, respectively.
The following
equations can be used to calculate R_high and R_low
values:
(
( )
)
(
Table 3 - PI33XX-X1 family output voltage ranges
The remote pin (REM) should always be connected
to the VOUT pin, if not used, to prevent an output
voltage offset. Figure 4 shows the internal feedback
voltage divider network.
VOUT
R4
REM
R_low
R1
ADJ
+
R_high
R2
1.0Vdc
SGND
(
)
)
(
( )
)
If, for example, a 4.0V output is needed, the user
should choose the regulator with a trim range
covering 4.0V from Table 3. For this example, the
PI3301 is selected (3.3V set voltage). First step
would be to use Equation (1) to calculate R_high
since the required output voltage is higher than the
regulator set voltage. The resistor-divider network
values for the PI3301 are can be found in Table 4 and
are R1=2.61kΩ and R2=1.13kΩ. Inserting these
values in to Equation (1), R_high is calculated as
follows:
(
Figure 4 - Internal resistor divider network
R1, R2, and R4 are all internal 1.0 % resistors and
R_low and R_high are external resistors for which
the designer can add to modify VOUT to a desired
output.
The internal resistor value for each
regulator is listed below in Table 4.
R4
100
100
100
100
)
(
)
Resistor R-high would be connected as in Figure 4 to
achieve the 4.0V regulator output. No R_low resistor
would be used since in this example the trim is
above the regulator set voltage.
The PI3311-X1 output voltage can only be trimmed
higher than the factory 1V setting. The following
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PI33XX-X1
equation (3) can be used to calculate Rhigh values for
the PI3311-X0 regulators.
(
)
(
)
through a divider (Figure 6) with the same ratio as
the slave’s feedback divider (see Table 4 for values).
( )
Master VOUT
The TRK pin offers a means to increase the
regulator’s soft-start time or to track with additional
regulators. The soft-start slope is controlled by an
internal capacitor and a fixed charge current to
provide a Soft-Start Time tSS for all PI33XX-X1
regulators.
By adding an additional external
capacitor to the TRK pin, the soft-start time can be
increased further. The following equation can be
used to calculate the proper capacitor for a desired
soft-start times:
(
R1
PI33XX
Soft-Start Adjust and Tracking
)
TRK
Slave
R2
SGND
Figure 6 - Voltage divider connections for direct tracking
All connected regulators’ soft-start slopes will track
with this method. Direct tracking timing is
demonstrated in Figure 5 (b). All tracking regulators
should have their Enable (EN) pins connected
together to work properly.
Inductor Pairing
Where, tTRK is the soft-start time and ITRK is a 50uA
internal charge current (see Electrical Characteristics
for limits).
There is typically either proportional or direct
tracking implemented within a design. For
proportional tracking between several regulators at
startup, simply connect all devices TRK pins
together. This type of tracking will force all
connected regulators to startup and reach regulation
at the same time (see Figure 5 (a)).
The PI33XX-X1 utilizes an external inductor. This
inductor has been optimized for maximum efficiency
performance. Table 5 details the specific inductor
value and part number utilized for each PI33XX-X1
device and are manufactured by Picor.
Device
PI3311-X1
PI3318-X1
PI3312-X1
PI3301-X1
Inductor
[nH]
80
125
125
150
Inductor
Part Number
PI60-02-FPIZ
PI60-04-FPIZ
PI60-04-FPIZ
PI60-05-FPIZ
Manufacturer
Picor
Picor
Picor
Picor
VOUT 1
Table 5 - PI33XX-X1 Inductor pairing
VOUT 2
(a)
Master VOUT
VOUT 2
(b)
t
Figure 5 - PI33XX-X1 tracking methods
For Direct Tracking, choose the regulator with the
highest output voltage as the master and connect
the master to the TRK pin of the other regulators
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PI33XX-X1
Layout Guidelines
To optimize maximum efficiency and low noise
performance from a PI33XX-X1 design, layout
considerations are necessary. Reducing trace
resistance and minimizing high current loop returns
along with proper component placement will
contribute to optimized performance.
A typical buck converter circuit is shown in Figure 9.
The potential areas of high parasitic inductance and
resistance are the circuit return paths, shown as LR
below.
When Q1 is on and Q2 is off, the majority of CIN’s
current is used to satisfy the output load and to
recharge the COUT capacitors. When Q1 is off and
Q2 is on, the load current is supplied by the inductor
and the COUT capacitor as shown in Figure 11.
During this period CIN is also being recharged by the
VIN. Minimizing CIN loop inductance is important to
reduce peak voltage excursions when Q1 turns off.
Also, the difference in area between the CIN loop
and COUT loop is vital to minimize switching and
GND noise.
Figure 9 - Typical Buck Converter
The path between the COUT and CIN capacitors is of
particular importance since the AC currents are
flowing through both of them when Q1 is turned on.
Figure 10, schematically, shows the reduced trace
length between input and output capacitors. The
shorter path lessens the effects that copper trace
parasitics can have on the PI33XX-X1 performance.
Figure 11 - Current flow: Q2 closed
The recommended component placement, shown in
Figure 12, illustrates the tight path between CIN and
COUT (and VIN and VOUT) for the high AC return
current. This optimized layout is used on the PI33XXX1 evaluation board.
Figure 10 - Current flow: Q1 closed
Figure 12 - Recommended component
placement and metal routing
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PI33XX-X1
Recommended PCB Footprint and Stencil
Figure 13 - Recommended Receiving PCB footprint.
Figure 133 details the recommended receiving footprint for PI33XX-X1 10mm x 14mm package. All pads should
have a final copper size of 0.55mm x 0.55mm, whether they are solder-mask defined or copper defined, on a 1mm
x 1mm grid. All stencil openings are 0.55mm when using a 6mil stencil.
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PI33XX-X1
Package Drawings
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PI33XX-X1
Warranty
Information furnished by Vicor is believed to be accurate and reliable. However, no responsibility is assumed by Vicor for its use.
Vicor makes no representations or warranties with respect to the accuracy or completeness of the contents of this publication. Vicor
reserves the right to make changes to any products, specifications, and product descriptions at any time without notice. Information
published by Vicor has been checked and is believed to be accurate at the time it was printed; however, Vicor assumes no
responsibility for inaccuracies. Testing and other quality controls are used to the extent Vicor deems necessary to support Vicor’s
product warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily
performed.
Specifications are subject to change without notice.
Vicor’s Standard Terms and Conditions
All sales are subject to Vicor’s Standard Terms and Conditions of Sale, which are available on Vicor’s webpage or upon request.
Product Warranty
In Vicor’s standard terms and conditions of sale, Vicor warrants that its products are free from non-conformity to its Standard
Specifications (the “Express Limited Warranty”). This warranty is extended only to the original Buyer for the period expiring two (2)
years after the date of shipment and is not transferable.
UNLESS OTHERWISE EXPRESSLY STATED IN A WRITTEN SALES AGREEMENT SIGNED BY A DULY AUTHORIZED VICOR
SIGNATORY, VICOR DISCLAIMS ALL REPRESENTATIONS, LIABILITIES, AND WARRANTIES OF ANY KIND (WHETHER
ARISING BY IMPLICATION OR BY OPERATION OF LAW) WITH RESPECT TO THE PRODUCTS, INCLUDING, WITHOUT
LIMITATION, ANY WARRANTIES OR REPRESENTATIONS AS TO MERCHANTABILITY, FITNESS FOR PARTICULAR
PURPOSE, INFRINGEMENT OF ANY PATENT, COPYRIGHT, OR OTHER INTELLECTUAL PROPERTY RIGHT, OR ANY
OTHER MATTER.
This warranty does not extend to products subjected to misuse, accident, or improper application, maintenance, or storage. Vicor
shall not be liable for collateral or consequential damage. Vicor disclaims any and all liability arising out of the application or use of
any product or circuit and assumes no liability for applications assistance or buyer product design. Buyers are responsible for their
products and applications using Vicor products and components. Prior to using or distributing any products that include Vicor
components, buyers should provide adequate design, testing and operating safeguards.
Vicor will repair or replace defective products in accordance with its own best judgment. For service under this warranty, the buyer
must contact Vicor to obtain a Return Material Authorization (RMA) number and shipping instructions. Products returned without
prior authorization will be returned to the buyer. The buyer will pay all charges incurred in returning the product to the factory. Vicor
will pay all reshipment charges if the product was defective within the terms of this warranty.
Life Support Policy
VICOR’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR
SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL
COUNSEL OF VICOR CORPORATION. As used herein, life support devices or systems are devices which (a) are intended for
surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with
instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. A critical
component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the
failure of the life support device or system or to affect its safety or effectiveness. Per Vicor Terms and Conditions of Sale, the user
of Vicor products and components in life support applications assumes all risks of such use and indemnifies Vicor against all liability
and damages.
Intellectual Property Notice
Vicor and its subsidiaries own Intellectual Property (including issued U.S. and Foreign Patents and pending patent applications)
relating to the products described in this data sheet. No license, whether express, implied, or arising by estoppel or otherwise, to
any intellectual property rights is granted by this document. Interested parties should contact Vicor's Intellectual Property
Department.
The products described on this data sheet are protected by the following U.S. Patents Numbers: RE 40,072.
Vicor Corporation
25 Frontage Road
Andover, MA, USA 01810 USA
Picor Corporation
51 Industrial Drive
North Smithfield, RI 02896 USA
Customer Service: [email protected]
Technical Support: [email protected]
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