FEATURES
n
LTC3882-1
Dual Output PolyPhase
Step-Down DC/DC Voltage Mode Controller
with Digital Power System Management
DESCRIPTION
The
LTC
®
3882-1
is a dual, PolyPhase DC/DC synchronous
step-down switching regulator controller with
PMBus
compliant serial interface.
It uses a constant frequency,
leading-edge modulation, voltage mode architecture for
excellent transient response and output regulation. Each
PWM channel can produce output voltages from 0.5V to
5.25V using a wide range of 3.3V compatible power stages,
including power blocks, DrMOS or discrete FET drivers.
Up to four LTC3882-1 devices can operate in parallel for
2-, 3-, 4-, 6- or 8-phase operation.
System configuration and monitoring is supported by the
LTpowerPlay™
software tool. The LTC3882-1 serial interface
can read back input voltage, output voltage and current,
temperature and fault status. Most operating parameters can
be set via the digital interface or stored in internal EEPROM
for use at power up. Switching frequency and phase, output
voltage and device address can also be set using external
configuration resistors.
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. Patents, including 5396245, 5859606, 6144194, 6937178, 7420359 and 7000125.
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PMBus/I
2
C Compliant Serial Interface
– Monitor Voltage, Current, Temperature and Faults
– Program Voltage, Soft-Start/Stop, Sequencing,
Margining, AVP and UV/OV/OC Limits
3V ≤ VINSNS ≤ 38V, 0.5V ≤ V
OUT
≤ 5.25V
±0.5% Output Voltage Error
Programmable PWM Frequency or External Clock
Synchronization from 250kHz to 1.25MHz
Accurate PolyPhase
®
Current Sharing
Internal EEPROM with Fault Logging and ECC
IC Supply Range: 3V to 13.2V
Resistor or Inductor DCR Current Sensing
Power Good Output Voltage Monitor
Optional Resistor Programming for Key Parameters
40-Pin (6mm
×
6mm) QFN Package
APPLICATIONS
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High Current Distributed Power Systems
Servers, Network and Storage Equipment
Intelligent Energy Efficient Power Regulation
TYPICAL APPLICATION
LTC3882
V
IN
7V TO 13.2V
+
V
CC
VINSNS V
SENSE0
PWM ENABLE
TG/BG
HW WRITE
OUTPUT
CONTROL PROTECT
•
•
•
LTC3882-1
DEDICATED
PGOOD OUTPUT
•
DIFFERENTIAL
V
OUT
SENSE
V
OUT0
Only
V
OUT0
&
V
OUT1
FB0
SDA
TO/FROM
MCU
SCL
ALERT
RUN0
RUN1
PGOOD0
FAULT0
TO/FROM
EXTERNAL DEVICES
PGOOD1
FAULT1
SYNC
SHARE_CLK
I
AVG0
I
AVG1
I
AVG_GND
LTC3882-1
COMP0
COMP1
PWM0
TSNS0
I
SENSE0+
I
SENSE0–
V
SENSE1+
I
SENSE1–
I
SENSE1+
FDMF5820DC
PWM
V
IN
SW
V
OUT
1V
70A
Load Step Transient Current Sharing
(Using FDMF5820DC DrMOS)
I
OUT
10A/DIV
GND
FDMF5820DC
PWM
V
IN
SW
PWM1
I
L0
, I
L1
10A/DIV
50µs/DIV
38821 TA01b
TSNS1
V
SENSE0–
–
GND V
SENSE1
INDUCTORS: COOPER FP1007R1-R22
SOME DETAILS OMITTED FOR CLARITY
GND
38821 TA01a
Rev A
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1
LTC3882-1
TABLE OF CONTENTS
Features ..................................................... 1
Applications ................................................ 1
Typical Application ........................................ 1
Description.................................................. 1
Absolute Maximum Ratings .............................. 4
Order Information .......................................... 4
Pin Configuration .......................................... 4
Electrical Characteristics ................................. 5
Typical Performance Characteristics ................... 9
Pin Functions .............................................. 13
Block Diagram............................................. 15
Test Circuit ................................................. 16
Timing Diagram ........................................... 16
Operation................................................... 16
Overview ............................................................ 16
Main Control Loop .............................................. 17
Power-Up and Initialization ................................. 19
Soft-Start ...........................................................20
Time-Based Output Sequencing .........................20
Output Ramping Control.....................................20
Voltage-Based Output Sequencing .....................20
Minimum Output Disable Times ......................... 21
Output Short Cycle ............................................. 21
Light Load Current Operation ............................. 21
Switching Frequency and Phase ......................... 21
PolyPhase Load Sharing.....................................22
Active Voltage Positioning ..................................22
Input Supply Monitoring .....................................22
Output Voltage Sensing and Monitoring .............22
Output Current Sensing and Monitoring .............22
External and Internal Temperature Sense ...........23
Resistor Configuration Pins ................................23
Internal EEPROM with CRC and ECC .................. 24
Fault Detection.................................................... 24
Input Supply Faults ............................................. 24
Hardwired PWM Response to V
OUT
Faults ......... 24
Power Good Indication (Master) .........................25
Power Good Indication (Slave) ...........................25
Hardwired PWM Response to I
OUT
Faults ..........25
Hardwired PWM Response to Temperature Faults.. 25
Hardwired PWM Response to Timing Faults ......26
External Faults ....................................................26
Fault Handling.....................................................26
Status Registers and
ALERT
Masking.................26
FAULT
Pin I/O...................................................... 28
Fault Logging ...................................................... 28
Factory Default Operation ................................... 31
Serial Interface ................................................... 32
Serial Bus Addressing ........................................ 32
Serial Bus Timeout .............................................36
Serial Communication Errors..............................36
PMBus Command Summary ............................ 37
PMBus Commands ............................................. 37
Data Formats ...................................................... 37
Applications Information ................................ 42
Efficiency Considerations ................................... 42
PWM Frequency and Inductor Selection............. 42
Power MOSFET Selection ...................................43
MOSFET Driver Selection ...................................44
Using PWM Protocols ........................................44
C
IN
Selection.......................................................44
C
OUT
Selection ....................................................45
Feedback Loop Compensation ............................46
PCB Layout Considerations ................................ 47
Output Current Sensing ......................................48
Output Voltage Sensing ......................................50
Soft-Start and Stop ............................................ 51
Time-Based Output Sequencing and Ramping ... 51
Voltage-Based Output Sequencing ..................... 52
Using Output Voltage Servo ...............................54
Using AVP ..........................................................54
PWM Frequency Synchronization.......................55
PolyPhase Operation and Load Sharing .............56
External Temperature Sense ...............................60
Resistor Configuration Pins ................................60
Internal Regulator Outputs .................................62
IC Junction Temperature.....................................62
Derating EEPROM Retention at Temperature ......63
Configuring Open-Drain Pins ..............................63
PMBus Communication and Command Processing ..64
Status and Fault Log Management .....................65
LTpowerPlay – An Interactive Digital Power GUI ... 65
Interfacing to the DC1613 ...................................66
Design Example ..................................................66
PMBus COMMAND DETAILS ............................. 69
Addressing and Write Protect .................................69
PAGE ..................................................................69
PAGE_PLUS_WRITE ..........................................69
PAGE_PLUS_READ ............................................ 70
WRITE_PROTECT ............................................... 70
MFR_ADDRESS ................................................. 71
MFR_RAIL_ADDRESS ....................................... 71
General Device Configuration ................................. 71
PMBUS_REVISION ............................................. 71
CAPABILITY........................................................ 71
On, Off and Margin Control..................................... 72
ON_OFF_CONFIG ................................................ 72
MFR_CONFIG_ALL_LTC3882-1 .........................72
OPERATION ........................................................73
MFR_RESET .......................................................73
PWM Configuration ................................................ 74
FREQUENCY_SWITCH ........................................ 74
Rev A
2
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LTC3882-1
TABLE OF CONTENTS
MFR_PWM_CONFIG_LTC3882-1 ....................... 75
MFR_CHAN_CONFIG_LTC3882-1 ...................... 76
MFR_PWM_MODE_LTC3882-1 .........................77
Input Voltage and Limits ......................................... 78
VIN_ON .............................................................. 78
VIN_OFF ............................................................. 78
VIN_OV_FAULT_LIMIT........................................ 78
VIN_UV_WARN_LIMIT ....................................... 78
Output Voltage and Limits ...................................... 79
VOUT_MODE ...................................................... 79
VOUT_COMMAND .............................................. 79
MFR_VOUT_MAX ............................................... 79
VOUT_MAX ........................................................80
MFR_VOUT_AVP ................................................80
VOUT_MARGIN_HIGH ........................................80
VOUT_MARGIN_LOW.........................................80
VOUT_OV_FAULT_LIMIT ....................................80
VOUT_OV_WARN_LIMIT .................................... 81
VOUT_UV_WARN_LIMIT .................................... 81
VOUT_UV_FAULT_LIMIT .................................... 81
Output Current and Limits ......................................82
IOUT_CAL_GAIN ................................................82
MFR_IOUT_CAL_GAIN_TC .................................82
IOUT_OC_FAULT_LIMIT .....................................82
IOUT_OC_WARN_LIMIT .....................................82
Output Timing, Delays, and Ramping .....................83
MFR_RESTART_DELAY ......................................83
TON_DELAY .......................................................83
TON_RISE ..........................................................83
TON_MAX_FAULT_LIMIT ...................................84
VOUT_TRANSITION_RATE .................................84
TOFF_DELAY ......................................................84
TOFF_FALL .........................................................84
TOFF_MAX_WARN_LIMIT..................................84
External Temperature and Limits ............................85
MFR_TEMP_1_GAIN ...........................................85
MFR_TEMP_1_OFFSET .......................................85
OT_FAULT_LIMIT................................................85
OT_WARN_LIMIT ...............................................85
Status Reporting.....................................................86
STATUS_BYTE....................................................86
UT_FAULT_LIMIT................................................86
STATUS_WORD .................................................. 87
STATUS_VOUT ................................................... 87
STATUS_IOUT .................................................... 87
STATUS_INPUT ..................................................88
STATUS_TEMPERATURE ....................................88
STATUS_CML .....................................................88
STATUS_MFR_SPECIFIC ....................................89
MFR_PADS_LTC3882-1 .....................................89
MFR_COMMON ..................................................90
MFR_INFO ..........................................................90
CLEAR_FAULTS..................................................90
Telemetry ................................................................ 91
READ_VIN .......................................................... 91
MFR_VIN_PEAK ................................................. 91
READ_VOUT ....................................................... 91
MFR_VOUT_PEAK .............................................. 91
READ_IOUT ........................................................92
MFR_IOUT_PEAK ...............................................92
READ_POUT.......................................................92
READ_TEMPERATURE_1 ...................................92
MFR_TEMPERATURE_1_PEAK ..........................92
READ_TEMPERATURE_2 ...................................92
MFR_TEMPERATURE_2_PEAK ..........................93
READ_DUTY_CYCLE ..........................................93
READ_FREQUENCY ............................................93
MFR_CLEAR_PEAKS .........................................93
Fault Response and Communication.......................94
VIN_OV_FAULT_RESPONSE ...............................94
VOUT_OV_FAULT_RESPONSE ............................95
VOUT_UV_FAULT_RESPONSE............................95
IOUT_OC_FAULT_RESPONSE.............................96
OT_FAULT_RESPONSE ....................................... 97
UT_FAULT_RESPONSE ....................................... 97
MFR_OT_FAULT_RESPONSE ............................. 97
TON_MAX_FAULT_RESPONSE ..........................98
MFR_RETRY_DELAY ..........................................98
SMBALERT_MASK .............................................98
MFR_FAULT_PROPAGATE_LTC3882-1 ..............99
MFR_FAULT_RESPONSE.................................. 100
MFR_FAULT_LOG ............................................. 101
Fault Log Operation .......................................... 101
MFR_FAULT_LOG_CLEAR................................ 101
EEPROM User Access ........................................... 102
STORE_USER_ALL .......................................... 102
RESTORE_USER_ALL ...................................... 102
MFR_COMPARE_USER_ALL ........................... 102
MFR_FAULT_LOG_STORE ............................... 103
MFR_EE_xxxx .................................................. 103
USER_DATA_0x ............................................... 103
Unit Identification ................................................. 103
MFR_ID ............................................................ 103
MFR_MODEL.................................................... 103
MFR_SERIAL.................................................... 103
MFR_SPECIAL_ID ............................................ 103
Typical Applications .................................... 104
Package Description ................................... 106
Revision History ........................................ 107
Typical Application ..................................... 108
Related Parts ............................................ 108
Rev A
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3
LTC3882-1
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
V
SENSE0+
V
SENSE0–
V
SENSE1–
V
SENSE1+
I
SENSE0+
I
SENSE0–
I
SENSE1–
V
OUT1_CFG
I
SENSE1+
30 I
AVG1
29 FB1
28 COMP1
27 PGOOD1
41
GND
26 PWM1
25 V
CC
24 V
DD33
23 SHARE_CLK
22 V
DD25
21 PHAS_CFG
11 12 13 14 15 16 17 18 19 20
FREQ_CFG
V
OUT0_CFG
ALERT
FAULT0
FAULT1
RUN0
RUN1
ASEL0
ASEL1
I
AVG0
V
CC
Supply Voltage .................................... –0.3V to 15V
VINSNS Voltage ......................................... –0.3V to 40V
V
SENSEn –
...................................................... –0.3V to 1V
V
SENSEn+
, I
SENSEn+
, I
SENSEn –
........................ –0.3V to 6V
FBn, COMPn, TSNSn, I
AVG_GND
, I
AVGn
...... –0.3V to 3.6V
SYNC,
FAULTn,
PGOODn, SHARE_CLK........–0.3V to 3.6V
SCL, SDA, RUNn,
ALERT
........................... –0.3V to 5.5V
ASELn, VOUTn_CFG, FREQ_CFG,
PHAS_CFG .............................................. –0.3V to 2.75V
PWMn, V
DD25
.................................................. (Note 13)
V
DD33
............................................................... (Note 14)
Operating Junction Temperature
(Notes 2, 3) .......................................... –40°C to 125°C*
Storage Temperature Range ................ –65°C to 150°C*
*See Derating EEPROM Retention at Temperature in the
Applications Information section for junction temperatures
in excess of 125°C.
COMP0 1
TSNS0 2
TSNS1 3
VINSNS 4
I
AVG_GND
5
PGOOD0 6
PWM0 7
SYNC 8
SCL 9
SDA 10
T
JMAX
= 125°C,
θ
JA
= 33°C/W ,
θ
JC
= 2.5°C/W
EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3882EUJ-1#PBF
LTC3882IUJ-1#PBF
TAPE AND REEL
LTC3882EUJ-1#TRPBF
LTC3882IUJ-1#TRPBF
http://www.linear.com/product/LTC3882-1#orderinfo
PART MARKING*
LTC3882UJ-1
LTC3882UJ-1
PACKAGE DESCRIPTION
40-Lead (6mm
×
6mm) Plastic QFN
40-Lead (6mm
×
6mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult LTC 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.
FB0
40 39 38 37 36 35 34 33 32 31
UJ PACKAGE
40-LEAD (6mm
×
6mm) PLASTIC QFN
Rev A
4
For more information
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LTC3882-1
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
J
= 25°C (Note 2). V
CC
= 5V, V
SENSE0+
= V
SENSE1+
= 1.8V, V
SENSE0–
=
V
SENSE1–
= I
AVG_GND
= GND = 0V, f
SYNC
= 500kHz (externally driven) unless otherwise specified.
SYMBOL
IC Supply
V
CC
V
DD33_EXT
V
UVLO
I
Q
t
INIT
V
CC
Voltage Range
V
DD33
Voltage Range
Undervoltage Lockout Threshold
IC Operating Current
Controller Initialization Time
Delay from RESTORE_USER_ALL, MFR_RESET or
V
DD33
> V
UVLO
Until TON_DELAY Can Begin
V
CC
≥ 4.5V
V
DD33
= 2.8V
V
DD33
= 0V
2.25
3.2
V
DD33
= Internal LDO
V
CC
= V
DD33
(Note 6)
V
DD33
Rising
Hysteresis
l
l
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
MIN
4.5
3
TYP
MAX
13.8
3.6
3
UNITS
V
V
V
mV
mA
ms
42
32
35
V
DD33
Linear Regulator
V
DD33
I
DD33
V
DD33
Regulator Output Voltage
V
DD33
Current Limit
3.3
85
40
2.5
95
3
278
0.6V ≤ V
OUT
≤ 5V
0.6V ≤ V
OUT
≤ 5V
0.6V ≤ V
OUT
≤ 2.5V
0.6V ≤ V
OUT
≤ 2.5V
V
SENSE+
= 5.5V
V
SENSE–
= 0V
4.5V ≤ V
CC
≤ 13.2V (See Test Circuit)
AVP = 10%, VOUT_COMMAND = 1.8V,
I
SENSE
Differential Step 3mV to 12mV
with IOUT_OC_WARN_LIMIT = 15mV
l
3.4
V
mA
mA
V
DD25
Linear Regulator
V
DD25
I
DD25
VINSNS
R
VINSNS
V
OUT_R0
V
DD25
Regulator Output Voltage
V
DD25
Current Limit
V
IN
Sense Voltage Range
VINSNS Input Resistance
Range 0 Maximum V
OUT
Range 0 Set Point Error (Note 7)
Range 0 Set Point Resolution
V
OUT_R1
Range 1 Maximum V
OUT
Range 1 Set Point Error (Note 7)
Range 1 Set Point Resolution
I
VSENSE
V
LINEREG
AVP
V
SENSE
Input Current
V
CC
Line Regulation, No Output Servo
AVP ∆V
OUT
Error Amplifier Open-Loop Voltage Gain
Error Amplifier Slew Rate
Error Amplifier Bandwidth
Error Amplifier Output Current
Resistance Between V
SENSE+
and FB
I
SENSE
Differential Input Range
I
SENSE
±
Input Current
2.75
V
mA
PWM Control Loops
38
5.25
±0.2
1.375
2.65
±0.2
0.6875
235
–335
–0.02
–118
–108
0.02
–96
V
kΩ
V
%
%
mV
V
%
%
mV
µA
µA
%/V
mV
l
–0.5
0.5
l
–0.5
0.5
A
V(OL)
SR
f
0dB
I
COMP
R
VSFB
V
ISENSE
I
ISENSE
I
AVG_VOS
V
SIOS
f
SYNC
87
9.5
(Note 12)
Sourcing
Sinking
Range 0
Range 1
0V ≤ V
PIN
≤ 5.5V
Referred to I
SENSE
Inputs
l
l
l
dB
V/µs
MHz
mA
mA
83
61
1
650
700
10
kΩ
kΩ
mV
µA
µV
µV
µV
µV
%
30
–2.6
34
52
37
–1
–600
–800
–10
67
49
±70
±0.1
±175
±300
I
AVG
Current Sense Offset
Slave Current Sharing Offset
SYNC Frequency Error
Referred to I
SENSE
Inputs
l
250kHz ≤ f
SYNC
≤ 1.25MHz
l
Rev A
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