LTC3884/LTC3884-1
Dual Output PolyPhase
Step-Down Controller with Sub-Milliohm DCR Sensing
and Digital Power System Management
FEATURES
DESCRIPTION
PMBus/I
2
C Compliant Serial Interface
– Telemetry Read-Back Includes V
IN
, I
IN
, V
OUT
, I
OUT
,
Temperature and Faults
– Programmable Voltage, Current Limit, Digital Soft-
Start/Stop, Sequencing, Margining, OV/UV/OC
n
Sub-Milliohm DCR Current Sensing
n
Digitally Adjustable Loop Compensation Parameters
n
±0.5% Output Voltage Accuracy Over Temperature
n
Integrated Input Current Sense Amplifier
n
Internal EEPROM with ECC and Fault Logging
n
Integrated N-Channel MOSFET Gate Drivers (LTC3884)
Power Conversion
n
Wide V Range: 4.5V to 38V
IN
n
V
OUT
Range: 0.5V to 3.5V (with Low DCR Setting);
0.5V to 5.5V (without Low DCR Setting)
n
Accurate PolyPhase
®
Current Sharing for Up to 6 Phases
n
Available in 48-Lead 7mm
×
7mm QFN and
5mm
×
6mm GQFN Packages.
n
The
LTC
®
3884/LTC3884-1
are dual output PolyPhase DC/
DC synchronous step-down switching regulator controllers
with an I
2
C-based
PMBus compliant serial interface.
The
controllers employ a constant-frequency current mode
architecture, together with a unique scheme to provide
excellent performance for sub-milliohm DCR applica-
tions. The LTC3884/LTC3884-1 are supported by the
LTpowerPlay
®
software development tool with graphical
user interface (GUI).
Programmable loop compensation allows the controller
to be compensated digitally. Switching frequency, channel
phasing, output voltage, and device address can be pro-
grammed both by the digital interface as well as external
configuration resistors. Additionally, parameters can be set
via the digital interface or stored in EEPROM. Both outputs
have independent power good indicators and
FAULT
function.
The LTC3884 has integrated gate drivers. The LTC3884-1
has three-state PWM pins to drive power blocks or DrMOS
power stages.
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258, 5408150,
7420359, 8648623, 8786265, 8823352, 7000125. Licensed under U.S. Patent 7000125 and
other related patents worldwide.
APPLICATIONS
n
n
Telecom, Datacom, and Storage Systems
Industrial and Point-of-Load Applications
TYPICAL APPLICATION
2m
10µF
×2
4.7µF
0.1µF
DCR =0.32m
L = 0.33µH
I
IN+
I
IN–
TG1
BOOST1
SW1
LTC3884*
BG1
FAULT MANAGEMENT
TO/FROM
OTHER LTC DEVICES
931
0.22µF
V
OUT1
1V
30A
330µF
×2
FAULT0
FAULT1
PGOOD0
PGOOD1
SHARE_CLK
I
SENSE1+
–
1µF
1
INTV
CC
TG0
BOOST0
SW0
BG0
SDA
SCL
ALERT
RUN0
RUN1
EXTV
CC
0.22µF
I
SENSE0+
–
V
IN
10µF
×2
0.1µF
DCR =0.32m
L= 0.33µH
V
IN
6V TO 15V
270µF
×2
Efficiency and Power Loss
vs Load Current
100
90
EFFICIENCY (%)
80
70
60
50
40
EFFICIENCY
POWER LOSS
0
5
10
15
20
LOAD CURRENT (A)
25
30
V
IN
= 12V
V
OUT
= 1.8V
EXTV
CC
=0
f
SW=
350kHz
6
5
4
3
2
1
0
POWER LOSS (W)
PMBus
INTERFACE
931
V
OUT0
1.8V
30A
330µF
×2
10nF
4700pF
220pF
I
SENSE0
I
SENSE1
V
SENSE1+
V
SENSE0+
V
SENSE0–
V
SENSE1–
TSNS0
TSNS1
I
TH0
I
TH1
I
THR0
I
THR1
V
DD33
PGND SGND V
DD25
1µF
3884 TA01b
2200pF
1µF
220pF
10nF
*SOME DETAILS OMITTED FOR CLARITY
3884 TA01a
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For more information
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1
LTC3884/LTC3884-1
TABLE OF CONTENTS
Features ..................................................... 1
Applications ................................................ 1
Typical Application ........................................ 1
Description.................................................. 1
Table of Contents .......................................... 2
Absolute Maximum Ratings .............................. 4
Pin Configuration .......................................... 4
Order Information .......................................... 5
Electrical Characteristics ................................. 6
Typical Performance Characteristics .................. 12
Pin Functions .............................................. 17
Block Diagram............................................. 19
Operation................................................... 20
Overview .................................................................20
Main Control Loop .................................................. 21
EEPROM ................................................................. 21
Power-Up and Initialization .....................................22
Soft-Start ................................................................23
Time-Based Sequencing .........................................23
Voltage-Based Sequencing .....................................23
Shutdown ............................................................... 24
Light-Load Current Operation ................................. 24
Switching Frequency and Phase .............................25
PWM Loop Compensation ......................................25
Output Voltage Sensing ..........................................25
INTV
CC
/EXTV
CC
Power ...........................................25
Output Current Sensing and Sub Milliohm DCR
Current Sensing ......................................................26
Input Current Sensing ............................................. 27
PolyPhase Load Sharing ......................................... 27
External/Internal Temperature Sense ...................... 27
RCONFIG (Resistor Configuration) Pins .................. 28
Fault Detection and Handling ..................................29
Status Registers and
ALERT
Masking .................29
Mapping Faults to
FAULT
Pins ............................ 31
Power Good Pins ................................................ 31
CRC Protection and ECC ..................................... 31
Serial Interface ....................................................... 32
Communication Protection ................................. 32
Device Addressing .................................................. 32
Responses to V
OUT
, I
IN
and I
OUT
Faults ................... 32
Output Overvoltage Fault Response ...................33
Output Undervoltage Response ..........................33
Peak Output Overcurrent Fault Response ...........33
Responses to Timing Faults ....................................33
Responses to V
IN
OV Faults ....................................34
Responses to OT/UT Faults.....................................34
Internal Overtemperature Fault Response ..........34
External Overtemperature and
Undertemperature Fault Response .....................34
Responses to Input Overcurrent and Output
Undercurrent Faults ................................................34
Responses to External Faults..................................34
Fault Logging ..........................................................34
Bus Timeout Protection ..........................................35
Similarity Between PMBus, SMBus and
I
2
C 2-Wire Interface ................................................35
PMBus Serial Digital Interface ................................35
PMBus Command Summary ............................ 40
PMBus Commands .................................................40
*Data Format ..........................................................45
Applications Information ................................ 46
Current Limit Programming ....................................46
I
SENSE0±
and I
SENSE1±
Pins......................................46
Inductor DCR Sensing ........................................ 47
Inductor Value Calculation ......................................48
Inductor Core Selection ..........................................48
Low Value Resistor Current Sensing.......................48
Slope Compensation and Inductor Peak Current .... 49
Power MOSFET and Optional Schottky Diode
Selection .................................................................50
Variable Delay Time, Soft-Start and Output
Voltage Ramping ....................................................50
Digital Servo Mode ................................................. 51
Soft Off (Sequenced Off) ........................................ 52
INTV
CC
/EXTV
CC
Power ........................................... 52
Topside MOSFET Driver Supply (C
B
, D
B
) ................53
Undervoltage Lockout.............................................54
C
IN
and C
OUT
Selection ...........................................54
2
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LTC3884/LTC3884-1
TABLE OF CONTENTS
Fault Indication .......................................................55
Open-Drain Pins .....................................................55
Phase-Locked Loop and Frequency
Synchronization .....................................................56
Minimum On-Time Considerations..........................56
External Temperature Sense ................................... 57
Input Current Sense Amplifier.................................58
External Resistor Configuration Pins (RCONFIG) ....58
Voltage Selection ................................................ 59
Frequency Selection ........................................... 59
Phase Selection ..................................................60
Address Selection Using RCONFIG .....................60
Efficiency Considerations ....................................... 61
Programmable Loop Compensation .......................62
Checking Transient Response .................................63
PolyPhase Configuration ....................................64
Master Slave Operation ......................................64
PC Board Layout Checklist ..................................... 67
PC Board Layout Debugging ................................... 67
Design Example ......................................................68
Additional Design Checks .......................................69
Connecting the USB to I
2
C/SMBus/PMBus
Controller to the LTC3884 in System ......................69
LTpowerPlay: An Interactive GUI for
Digital Power .......................................................... 70
PMBus Communication and Command
Processing .............................................................. 70
PMBus Command Details ............................... 73
Addressing and Write Protect .................................73
General Configuration Commands .......................... 75
On/Off/Margin ........................................................ 76
PWM Configuration ................................................ 78
Voltage.................................................................... 81
Input Voltage and Limits..................................... 81
Output Voltage and Limits .................................. 82
Output Current and Limits ......................................85
Input Current and Limits .................................... 87
Temperature............................................................88
External Temperature Calibration........................88
Timing ....................................................................89
Timing—On Sequence/Ramp.............................89
Timing—Off Sequence/Ramp ............................90
Precondition for Restart ..................................... 91
Fault Response ....................................................... 91
Fault Responses All Faults .................................. 91
Fault Responses Input Voltage ...........................92
Fault Responses Output Voltage .........................92
Fault Responses Output Current .........................95
Fault Responses IC Temperature ........................96
Fault Responses External Temperature............... 97
Fault Sharing...........................................................98
Fault Sharing Propagation ..................................98
Fault Sharing Response .................................... 100
Scratchpad ........................................................... 100
Identification ......................................................... 101
Fault Warning and Status...................................... 102
Telemetry .............................................................. 109
NVM Memory Commands .................................... 113
Store/Restore ................................................... 113
Fault Log Operation .......................................... 114
Fault Logging .................................................... 114
Block Memory Write/Read................................ 118
Typical Applications .................................... 119
Package Description ................................... 125
Revision History ........................................ 127
Typical Application ..................................... 128
Related Parts ............................................ 128
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3
LTC3884/LTC3884-1
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V
IN
, I
IN+
, I
IN –
.............................................. –0.3V to 40V
(V
IN
– I
IN+
), (I
IN+
– I
IN –
) ............................. –0.3V to 0.3V
BOOST0, BOOST1 (LTC3884) .................... –0.3V to 46V
Switch Transient Voltage (SW0, SW1)
(LTC3884)................................................. –5V to 40V
(BOOST0-SW0), (BOOST1-SW1)
(LTC3884)................................................ –0.3V to 6V
Top Gate Transient Voltage TG0, TG1
(LTC3884)................................................–5V TO 46V
V
CC0
, V
CC1
(LTC3884-1) ............................... –0.3V to 6V
Top Gate Transient Voltage PWM0, PWM1
(LTC3884-1) ............................................. –0.3V to 6V
I
SENSE0+
, I
SENSE0 –
, I
SENSE1+
, I
SENSE1–
,
V
SENSE0+
, V
SENSE1+
...................................... –0.3V to 6V
V
SENSE0 –
, V
SENSE1–
................................... –0.3V to 0.3V
EXTV
CC
, INTV
CC
........................................... –0.3V to 6V
(EXTV
CC
– V
IN
) ........................................................5.5V
PGOOD0, PGOOD1.................................... –0.3V to 3.6V
RUN0, RUN1, SDA, SCL,
ALERT
................ –0.3V to 5.5V
ASEL0, ASEL1, V
OUT0_CFG0
, V
OUT1_CFG
,
FREQ_CFG, PHASE_CFG .................... –0.3V to 2.75V
FAULT0, FAULT1,
SHARE_CLK, WP, SYNC –0.3V to 3.6V
TSNS0, TSNS1 .......................................... –0.3V to 3.6V
I
TH0
, I
TH1
, I
THR0
, I
THR1
.............................. –0.3V to 3.6V
Operating Junction Temperature Range
(Notes 2, 17, 18) .......................................–40°C to 125°C
Storage Temperature Range ................ –65°C to 150°C*
*See Derating EEPROM Retention at Temperature in Applications Informa-
tion section for junction temperatures in excess of 125°C.
PIN CONFIGURATION
LTC3884
48 PGOOD0
47 I
IN–
46 I
IN+
45 SW0
44 TG0
43 BOOST0
42 BG0
41 PGND
40 EXTV
CC
39 V
IN
38 INTV
CC
37 BG1
TOP VIEW
LTC3884
TOP VIEW
48 I
IN–
47 I
IN+
46 SW0
45 TG0
44 BOOST0
43 BG0
42 PGND
41 EXTV
CC
40 V
IN
39 INTV
CC
36 BOOST1
35 TG1
34 SW1
33 PGOOD1
32 V
SENSE1+
31 V
SENSE1–
30 I
THR1
29 I
TH1
28 V
DD33
27 SHARE_CLK
26 WP
25 V
DD25
PGOOD0 1
V
SENSE0+
2
V
SENSE0–
3
I
SENSE1+
4
I
SENSE1–
5
I
THR0
6
I
TH0
7
I
SENSE0+
8
I
SENSE0–
9
TSNS1 10
TSNS0 11
SYNC 12
SCL 13
SDA 14
49
49
49
SGND
49
49
38 BG1
37 BOOST1
36 TG1
35 SW1
34 PGOOD1
33 V
SENSE1+
32 V
SENSE1–
31 I
THR1
30 I
TH1
29 V
DD33
28 SHARE_CLK
27 WP
26 V
DD25
25 PHASE_CFG
RHE PACKAGE
48-LEAD (5mm
×
6mm) PLASTIC GQFN
T
JMAX
= 125°C,
θ
JA
= 31°C/W,
θ
JC
= 3.7°C/W
EXPOSED PADS (PIN 49) ARE SGND, MUST BE SOLDERED TO PCB
ALERT
15
FAULT0
16
FAULT1
17
RUN0 18
RUN1 19
ASEL0 20
ASEL1 21
V
OUT0_CFG
22
V
OUT1_CFG
23
FREQ_CFG 24
V
SENSE0+
1
V
SENSE0–
2
I
SENSE1+
3
I
SENSE1–
4
I
THR0
5
I
TH0
6
I
SENSE0+
7
I
SENSE0–
8
TSNS1 9
TSNS0 10
SYNC 11
SCL 12
49
SGND
UK PACKAGE
48-LEAD (7mm
×
7mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 31°C/W,
θ
JC
= 3°C/W
EXPOSED PAD (PIN 49) IS SGND, MUST BE SOLDERED TO PCB
SDA 13
ALERT
14
FAULT0
15
FAULT1
16
RUN0 17
RUN1 18
ASEL0 19
ASEL1 20
V
OUT0_CFG
21
V
OUT1_CFG
22
FREQ_CFG 23
PHASE_CFG 24
4
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For more information
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LTC3884/LTC3884-1
PIN CONFIGURATION
LTC3884-1
TOP VIEW
48 I
IN–
47 I
IN+
46 NC
45 PWM0
44 VCC0
43 NC
42 PGND
41 EXTV
CC
40 V
IN
39 INTV
CC
PGOOD0 1
V
SENSE0+
2
V
SENSE0–
3
I
SENSE1+
4
I
SENSE1–
5
I
THR0
6
I
TH0
7
I
SENSE0+
8
I
SENSE0–
9
TSNS1 10
TSNS0 11
SYNC 12
SCL 13
SDA 14
49
49
49
SGND
49
49
38 NC
37 V
CC1
36 PWM1
35 NC
34 PGOOD1
33 V
SENSE1+
32 V
SENSE1–
31 I
THR1
30 I
TH1
29 V
DD33
28 SHARE_CLK
27 WP
26 V
DD25
25 PHASE_CFG
RHE PACKAGE
48-LEAD (5mm
×
6mm) PLASTIC GQFN
T
JMAX
= 125°C,
θ
JA
= 31°C/W,
θ
JC
= 3.7°C/W
EXPOSED PADS (PIN 49) ARE SGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
ALERT
15
FAULT0
16
FAULT1
17
RUN0 18
RUN1 19
ASEL0 20
ASEL1 21
V
OUT0_CFG
22
V
OUT1_CFG
23
FREQ_CFG 24
(http://www.linear.com/product/LTC3884#orderinfo)
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3884EUK#PBF
LTC3884EUK#TRPBF
LTC3884 UK
48-Lead (7mm
×
7mm) Plastic QFN
–40°C to 125°C
LTC3884IUK#PBF
LTC3884IUK#TRPBF
LTC3884 UK
48-Lead (7mm
×
7mm) Plastic QFN
–40°C to 125°C
LTC3884ERHE#PBF
LTC3884ERHE#TRPBF
LTC3884
48-Lead (5mm
×
6mm) Plastic GQFN
–40°C to 125°C
LTC3884IRHE#PBF
LTC3884IRHE#TRPBF
LTC3884
48-Lead (5mm
×
6mm) Plastic GQFN
–40°C to 125°C
LTC3884ERHE-1#PBF
LTC3884ERHE-1#TRPBF LTC3884-1
48-Lead (5mm
×
6mm) Plastic GQFN
–40°C to 125°C
LTC3884IRHE-1#PBF
LTC3884IRHE-1#TRPBF LTC3884-1
48-Lead (5mm
×
6mm) Plastic GQFN
–40°C to 125°C
Consult ADI Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
3884fe
For more information
www.linear.com/LTC3884
5
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