FEATURES
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LTC2975
4-Channel PMBus Power
System Manager Featuring Accurate
Input Current and Energy Measurement
DESCRIPTION
The
LTC
®
2975
is a 4-channel Power System Manager used
to sequence, trim (servo), margin, supervise, manage faults,
provide telemetry and create fault logs. PMBus commands
support power supply sequencing, precision point-of-load
voltage adjustment and margining. DACs use a proprietary
soft-connect algorithm to minimize supply disturbances.
Supervisory functions include over and under current,
voltage and temperature threshold limits for four power
supply output channels as well as over and under voltage
threshold limits for a single power supply input channel.
Programmable fault responses can disable the power sup-
plies with optional retry after a fault is detected. Faults that
disable a power supply can automatically trigger black box
EEPROM storage of fault status and associated telemetry.
An internal 16-bit ADC monitors four output voltages, four
output currents, four external temperatures, input voltage
and current, and die temperature. Input power, energy,
and output power is also calculated. A programmable
watchdog timer monitors microprocessor activity for a
stalled condition and resets the microprocessor if neces-
sary. A single wire bus synchronizes power supplies across
multiple LTC Power System Management (PSM) devices.
Configuration EEPROM with ECC supports autonomous
operation without additional software.
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. patents, including 7382303, 7420359 and 8648623.
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Sequence, Trim, Margin and Supervise Four Power
Supplies
Manage Faults, Monitor Telemetry and Create Fault Logs
PMBus™ Compliant Command Set
Supported by LTpowerPlay
®
GUI
Margin or Trim Supplies to Within 0.25% of Target
Monitor Input Current (±1%) and Accumulate Energy
Fast OV/UV and OC Supervisors Per Channel
Coordinate Sequencing and Fault Management
Across Multiple LTC PSM Devices
Automatic Fault Logging to Internal EEPROM
Operate Autonomously Without Additional Software
External Temperature and Input Voltage Supervisors
Accurate Monitoring of Four Output Voltages, Four
Output Currents, Four External Temperatures, Input
Voltage and Current, and Internal Die Temperature
Can Be Powered from 3.3V, or 4.5V to 15V
Pin-Compatible to the LTC2974
Available in 64-Lead 9mm × 9mm QFN Package and in
63-Lead 6.25mm × 7.5mm BGA Package
Computers and Network Servers
Industrial Test and Measurement
High Reliability Systems
Video and Medical Imaging
APPLICATIONS
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TYPICAL APPLICATION
4-Channel PMBus Power System Manager with Input Energy Metering
DC
IN
IN
IBC
4.5V ≤ V
IBUS
≤ 15V
OUT
EN
I
IN_SNSP
V
IN_SNS
AUXFAULTB
*LTC2975 MAY ALSO BE
POWERED DIRECTLY FROM
AN EXTERNAL 3.3V SUPPLY
V
PWR
*
V
DD33
*
I
SENSEM
V
SENSEP
LOAD
R20
R30
V
DAC
Power Measurement Error
2
Mfr_ein_config_iin_range = Medium
V
IIN_SNS
= 50mV
V
VIN_SNS
= 12V
I
IN_SNSM
I
SENSEP
V
OUT
V
IN
1
ERROR (%)
DC/DC
CONVERTER
V
FB
RUN
0
LTC2975
PMBus
INTERFACE
SDA
SCL
ALERTB
CONTROL
V
OUT_EN
FAULT
T
SENSE
PWRGD
GND
NOTE: SOME DETAILS OMITTED FOR CLARITY
ONLY ONE OF FOUR CHANNELS SHOWN
V
SENSEM
–1
R10
MMBT3906
2975 TA01
6 TYPICAL PARTS
–2
0
25
–50 –25
50
75
TEMPERATURE (°C)
100
2975 TA01b
Rev. B
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1
LTC2975
TABLE OF CONTENTS
Features ..........................................................................1
Applications .....................................................................1
Typical Application .............................................................1
Description.......................................................................1
Absolute Maximum Ratings ...................................................4
Pin Configuration ...............................................................4
Order Information ...............................................................5
Electrical Characteristics ......................................................5
PMBus Timing Diagram...................................................... 10
Typical Performance Characteristics ...................................... 11
Pin Functions .................................................................. 15
Block Diagram................................................................. 17
Operation....................................................................... 18
LTC2975 Operation Overview .......................................................... 18
EEPROM ..................................................................................... 19
AUXFAULTB ..................................................................................... 19
RESETB ............................................................................................20
PMBus Serial Digital Interface.........................................................20
PMBus ........................................................................................20
Device Address...........................................................................20
Processing Commands ..............................................................21
PMBUS Command Summary ................................................ 24
PMBus Command Description .............................................. 30
Addressing and Write Protect..........................................................30
PAGE ...........................................................................................30
WRITE_PROTECT ......................................................................31
Write Protect Pin ........................................................................31
MFR_PAGE_FF_MASK ...............................................................31
MFR_I2C_BASE_ADDRESS .......................................................32
MFR_COMMAND_PLUS ............................................................32
MFR_DATA_PLUS0 and MFR_DATA_PLUS1 ............................32
MFR_STATUS_PLUS0, and MFR_STATUS_PLUS1...................32
Reading Fault Log Using Command Plus and
Mfr_data_plus0 ..........................................................................33
Reading Energy Using MFR_COMMAND_PLUS and
MFR_DATA_PLUS0 ....................................................................34
Peek Operation Using Mfr_data_plus0 ......................................34
Enabling and Disabling Poke Operations ...................................34
Poke Operation Using Mfr_data_plus0 ......................................34
Command Plus Operations Using Mfr_data_plus1....................35
On/Off Control, Margining and Configuration .................................35
OPERATION ................................................................................35
ON_OFF_CONFIG ........................................................................36
MFR_CONFIG_LTC2975.............................................................37
Cascade Sequence ON with Time-Based Sequence OFF ...........38
MFR_CONFIG2_LTC2975...........................................................39
MFR_CONFIG3_LTC2975...........................................................40
Tracking Supplies On and Off .....................................................41
Tracking Implementation............................................................44
MFR_CONFIG_ALL_LTC2975 ....................................................44
Programming User EEPROM Space ................................................46
STORE_USER_ALL and RESTORE_USER_ALL ........................46
Bulk Programming the User EEPROM Space .............................46
MFR_EE_UNLOCK......................................................................47
MFR_EE_ERASE ........................................................................47
MFR_EE_DATA ...........................................................................47
Response When Part Is Busy .....................................................48
MFR_EE Erase and Write Programming Time ...........................48
Input Voltage Commands and Limits ..............................................48
VIN_ON, VIN_OFF, VIN_OV_FAULT_LIMIT, VIN_OV_WARN_
LIMIT, VIN_UV_WARN_LIMIT and
VIN_UV_FAULT_LIMIT ...............................................................48
Input Current and Energy.................................................................49
Energy Measurement and Reporting .........................................49
MFR_EIN ...................................................................................49
MFR_EIN_CONFIG .....................................................................50
MFR_IIN_CAL_GAIN ..................................................................50
MFR_IIN_CAL_GAIN_TC ........................................................... 51
MFR_CLEAR_ENERGY............................................................... 51
Output Voltage Commands and Limits ............................................51
VOUT_MODE ..............................................................................52
VOUT_COMMAND, VOUT_MAX, VOUT_MARGIN_HIGH,
VOUT_MARGIN_LOW, VOUT_OV_FAULT_LIMIT,
VOUT_OV_WARN_LIMIT, VOUT_UV_WARN_LIMIT,
VOUT_UV_FAULT_LIMIT, POWER_GOOD_ON and
POWER_GOOD_OFF...................................................................52
MFR_VOUT_DISCHARGE_THRESHOLD ....................................52
MFR_DAC ...................................................................................52
Output Current Commands and Limits ............................................53
IOUT_CAL_GAIN ........................................................................53
IOUT_OC_FAULT_LIMIT, IOUT_OC_WARN_LIMIT and
IOUT_UC_FAULT_LIMIT .............................................................53
MFR_IOUT_CAL_GAIN_TC ........................................................53
External Temperature Commands and Limits .................................54
OT_FAULT_LIMIT, OT_WARN_LIMIT, UT_WARN_LIMIT and
UT_FAULT_LIMIT .......................................................................55
MFR_TEMP_1_GAIN and MFR_TEMP_1_OFFSET......................55
MFR_T_SELF_HEAT, MFR_IOUT_CAL_GAIN_TAU_INV and
MFR_IOUT_CAL_GAIN_THETA ..................................................55
Sequencing Timing Limits and Clock Sharing .................................57
TON_DELAY, TON_RISE, TON_MAX_FAULT_LIMIT and
TOFF_DELAY ..............................................................................57
Watchdog Timer and Power Good ...................................................58
MFR_PWRGD_EN ......................................................................58
MFR_RESTART_DELAY .............................................................58
Clock Sharing .............................................................................58
MFR_POWERGOOD_ASSERTION_DELAY ................................59
Watchdog Operation ..................................................................59
MFR_WATCHDOG_T_FIRST and MFR_WATCHDOG_T..............59
Fault Responses...............................................................................60
Clearing Latched Faults ..............................................................60
VOUT_OV_FAULT_RESPONSE and VOUT_UV_FAULT_
RESPONSE .................................................................................60
IOUT_OC_FAULT_RESPONSE and
IOUT_UC_FAULT_RESPONSE ....................................................61
OT_FAULT_RESPONSE, UT_FAULT_RESPONSE, VIN_OV_
FAULT_RESPONSE and VIN_UV_FAULT_RESPONSE................62
TON_MAX_FAULT_RESPONSE .................................................63
MFR_RETRY_DELAY .................................................................63
MFR_RETRY_COUNT .................................................................63
Shared External Faults .....................................................................64
MFR_FAULTB0_PROPAGATE and
MFR_FAULTB1_PROPAGATE .....................................................64
Rev. B
2
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LTC2975
TABLE OF CONTENTS
MFR_FAULTB0_RESPONSE and
MFR_FAULTB1_RESPONSE .......................................................64
Fault Warning and Status ................................................................65
CLEAR_FAULTS .........................................................................65
STATUS_BYTE ...........................................................................66
STATUS_WORD..........................................................................66
STATUS_VOUT ...........................................................................67
STATUS_IOUT ............................................................................67
STATUS_INPUT ..........................................................................67
STATUS_TEMPERATURE ...........................................................68
STATUS_CML .............................................................................68
STATUS_MFR_SPECIFIC ...........................................................68
MFR_PADS.................................................................................69
MFR_COMMON ..........................................................................70
Telemetry .........................................................................................71
READ_VIN ..................................................................................71
READ_IIN ...................................................................................71
READ_PIN ..................................................................................71
READ_VOUT ...............................................................................71
READ_IOUT ................................................................................72
MFR_IIN_PEAK ..........................................................................72
MFR_IIN_MIN ............................................................................72
MFR_PIN_PEAK .........................................................................72
MFR_PIN_MIN ...........................................................................72
READ_TEMPERATURE_1 ...........................................................72
READ_TEMPERATURE_2...........................................................72
READ_POUT ...............................................................................73
MFR_READ_IOUT ......................................................................73
MFR_IOUT_SENSE_VOLTAGE ................................................... 74
MFR_VIN_PEAK ......................................................................... 74
MFR_VOUT_PEAK ...................................................................... 74
MFR_IOUT_PEAK ....................................................................... 74
MFR_TEMPERATURE_1_PEAK .................................................. 74
MFR_VIN_MIN ........................................................................... 74
MFR_VOUT_MIN ........................................................................ 74
MFR_IOUT_MIN .........................................................................75
MFR_TEMPERATURE_1_MIN ....................................................75
Fault Logging ...................................................................................75
Fault Log Operation ....................................................................75
MFR_FAULT_LOG_STORE .........................................................75
MFR_FAULT_LOG_RESTORE ....................................................76
MFR_FAULT_LOG_CLEAR .........................................................76
MFR_FAULT_LOG_STATUS .......................................................76
MFR_FAULT_LOG.......................................................................76
MFR_FAULT_LOG Read Example...............................................79
Identification/Information................................................................83
CAPABILITY................................................................................83
User Scratchpad ..............................................................................84
USER_DATA_00, USER_DATA_01, USER_DATA_02, USER_
DATA_03, USER_DATA_04, MFR_LTC_RESERVED_1 and
MFR_LTC_RESERVED_2 ...........................................................84
PMBUS_REVISION.....................................................................84
MFR_SPECIAL_ID ......................................................................84
MFR_SPECIAL_LOT ...................................................................84
MFR_INFO ..................................................................................84
Applications Information .................................................... 85
Overview ..........................................................................................85
Powering the LTC2975.....................................................................85
Setting Command Register Values ..................................................85
Measuring Input Current..................................................................85
Measuring Input Voltage..................................................................87
Measuring Input Power ...................................................................87
Measuring Input Energy ..................................................................87
Sequence, Servo, Margin and Restart Operations ..........................87
Command Units On or Off ..........................................................87
On Sequencing ...........................................................................88
On State Operation .....................................................................88
Servo Modes ..............................................................................88
DAC Modes .................................................................................88
Margining ...................................................................................89
Off Sequencing ...........................................................................89
V
OUT
Off Threshold Voltage .......................................................89
Automatic Restart via MFR_RESTART_DELAY Command and
CONTROL Pin .............................................................................89
Fault Management ...........................................................................90
Output Overvoltage, Undervoltage, Overcurrent and
Undercurrent Faults ...................................................................90
Output Overvoltage, Undervoltage, and
Overcurrent Warnings ................................................................90
Configuring the AUXFAULTB Output ..........................................90
Multi-Channel Fault Management ..............................................90
Interconnect Between Multiple LTC POWER MANAGERS...............92
Application Circuits..........................................................................93
Trimming and Margining DC/DC Converters with External
Feedback Resistors ....................................................................93
Four-Step Resistor Selection Procedure for DC/DC Converters
with External Feedback Resistors ..............................................94
Trimming and Margining DC/DC Converters with a TRIM Pin ...94
Two-Step Resistor and DAC Full-Scale Voltage Selection
Procedure for DC/DC Converters with a TRIM Pin ....................95
Measuring Output with a Sense Resistor...................................95
Measuring Output with Inductor DCR ........................................95
Single Phase Design Example ....................................................96
Measuring Multiphase Currents .................................................96
Multiphase Design Example .......................................................96
Anti-aliasing Filter Considerations .............................................96
Sensing Negative Voltages .........................................................97
Connecting the DC1613 USB to I
2
C/SMBus/PMBus
Controller to the LTC2975 in System .........................................97
Accurate DCR Temperature Compensation .....................................98
LTpowerPlay: An Interactive GUI for Power Managers..................101
PCB Assembly and Layout Suggestions........................................102
Bypass Capacitor Placement....................................................102
Exposed Pad Stencil Design.....................................................102
PCB Board Layout ....................................................................102
Unused ADC Sense Inputs .......................................................102
Design Checklist ............................................................................103
Package Description ........................................................104
Revision History .............................................................107
Typical Application ..........................................................108
Related Parts .................................................................108
Rev. B
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3
LTC2975
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Supply Voltages:
V
PWR
...................................................... –0.3V to 15V
V
DD33
.................................................... –0.3V to 3.6V
V
DD25
.................................................. –0.3V to 2.75V
Digital Input/Output Voltages:
ALERTB, SDA, SCL, CONTROL0, CONTROL1,
CONTROL2, CONTROL3 ....................... –0.3V to 3.6V
PWRGD, SHARE_CLK, WDI/RESETB,
WP, FAULTB0, FAULTB1........................ –0.3V to 3.6V
ASEL0, ASEL1 ....................................... –0.3V to 3.6V
Analog Voltages:
REFP ................................................... –0.3V to 1.35V
REFM .................................................... –0.3V to 0.3V
V
IN_SNS
, V
IN_SNS_CAP
............................ –0.3V to 15V
I
IN_SNSP
, I
IN_SNSM
to V
IN_SNS
............... –0.3V to 0.3V
V
SENSEP[3:0]
............................................. –0.3V to 6V
V
SENSEM[3:0]
............................................. –0.3V to 6V
I
SENSEP[3:0]
............................................... –0.3V to 6V
I
SENSEM[3:0]
.............................................. –0.3V to 6V
V
OUT_EN[3:0]
, AUXFAULTB ...................... –0.3V to 15V
V
DAC[3:0]
.................................................. –0.3V to 6V
T
SENSE[3:0]
............................................ –0.3V to 3.6V
I
IN_SNSP
, I
IN_SNSM
.................................. –0.3V to 15V
Operating Junction Temperature Range:
LTC2975C ................................................ 0°C to 70°C
LTC2975I ........................................... –40°C to 105°C
Storage Temperature Range ................ –65°C to 150°C*
Maximum Junction Temperature ........................ 125°C*
*See OPERATION section for detailed EEPROM derating
information for junction temperatures in excess of 105°C.
PIN CONFIGURATION
64 V
SENSEM1
63 V
SENSEP1
62 V
SENSEM2
61 V
SENSEP2
60 GND
59 GND
58 V
DAC3
57 V
DAC2
56 I
IN_SNSM
55 I
IN_SNSP
54 V
DAC1
53 V
DAC0
52 GND
51 V
IN_SNS_CAP
50 V
SENSEM3
49 V
SENSEP3
TOP VIEW
TOP VIEW
V
DAC0
4
5
I
IN_SNSM
1
48 I
SENSEM3
47 I
SENSEP3
46 I
SENSEM2
45 I
SENSEP2
44 I
SENSEM1
43 I
SENSEP1
42 I
SENSEM0
41 I
SENSEP0
40 REFM
39 GND
38 REFP
37 GND
36 ASEL1
35 ASEL0
34 T
SENSE3
33 CONTROL1
V
SENSEM1
A
V
DAC3
2
3
V
SENSEP1
V
SENSEP0
6
7
V
SENSEM3
V
SENSEP3
I
SENSEM2
I
SENSEP2
I
SENSEP1
T
SENSE3
CONTROL1
CONTROL0
I
SENSEM0
V
SENSEP0
1
V
SENSEM0
2
V
OUT_EN0
3
V
OUT_EN1
4
V
OUT_EN2
5
V
OUT_EN3
6
AUXFAULTB 7
DNC 8
V
IN_SNS
9
V
PWR
10
V
DD33
11
V
DD33
12
V
DD25
13
V
DD25
14
T
SENSE0
15
T
SENSE1
16
V
IN_SNS_CAP
V
SENSEP2
V
SENSEM0
B
V
OUT_EN0
V
OUT_EN1
C
V
OUT_EN2
V
OUT_EN3
D
AUXFAULTB
T
SENSE0
E
F
CONTROL2
G
I
IN_SNSP
V
DAC1
I
SENSEM3
V
SENSEM2
V
DAC2
GND I
SENSEP3
GND
DNC V
IN_SNS
V
DD33
GND
I
SENSEM1
65
GND
GND ASEL1 I
SENSEP0
T
SENSE1
GND GND REFP REFM
ASEL0
V
DD25
V
PWR
GND GND T
SENSE2
WDI/RESETB
PWRGD
FAULTB0 WP
SDA
SCL
V
DD25
H
J
PWRGD 17
SHARE_CLK 18
GND 19
GND 20
GND 21
CONTROL2 22
CONTROL3 23
WDI/RESETB 24
FAULTB0 25
FAULTB1 26
T
SENSE2
27
WP 28
SDA 29
SCL 30
ALERTB 31
CONTROL0 32
CONTROL3
FAULTB1
SHARE_CLK
ALERTB
UP PACKAGE
64-LEAD (9mm
×
9mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JCtop
= 7°C/W,
θ
JCbottom
= 1°C/W
EXPOSED PAD (PIN 65) IS GND, MUST BE SOLDERED TO PCB
BGA PACKAGE
63-PIN (7.5mm
×
6.25mm
×
1.52mm)
T
JMAX
= 125°C,
θ
JA
= 45°C/W,
θ
JCtop
= 25°C/W,
θ
JCbottom
= 21°C/W,
θ
JB
= 23°C/W
WEIGHT = 0.14g, VALUES DETERMINED PER JEDEC 51-9, 51-12
Rev. B
4
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LTC2975
ORDER INFORMATION
LEAD FREE FINISH
LTC2975CUP#PBF
LTC2975IUP#PBF
TAPE AND REEL
LTC2975CUP#TRPBF
LTC2975IUP#TRPBF
PART MARKING*
LTC2975UP
LTC2975UP
PACKAGE DESCRIPTION
64-Lead (9mm × 9mm) Plastic QFN
64-Lead (9mm × 9mm) Plastic QFN
JUNCTION TEMPERATURE RANGE
0°C to 70°C
–40°C to 105°C
Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
PART MARKING*
PART NUMBER
LTC2975CY#PBF
LTC2975IY#PBF
PAD OR BALL FINISH
SAC305 (RoHS)
DEVICE
LTC2975Y
LTC2975Y
FINISH CODE
e1
PACKAGE
TYPE
BGA
MSL
RATING
3
TEMPERATURE RANGE
(SEE NOTE 2)
0°C to 70°C
–40°C to 105°C
• Contact the factory for parts specified with wider operating temperature
ranges. *Pad or ball finish code is per IPC/JEDEC J-STD-609.
•
Recommended LGA and BGA PCB Assembly and Manufacturing
Procedures
•
LGA and BGA Package and Tray Drawings
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
J
= 25°C. V
PWR
= V
IN_SNS
= 12V, V
DD33
, V
DD25
, REFP and REFM pins floating,
unless otherwise indicated. C
VDD33
= 100nF, C
VDD25
= 100nF, C
VIN_SNS_CAP
= 10nF and C
REF
= 100nF. (Note 2)
SYMBOL
V
PWR
I
PWR
I
VDD33
V
UVLO_VDD33
PARAMETER
V
PWR
Supply Input Operating Range
V
PWR
Supply Current
V
DD33
Supply Current
V
DD33
Undervoltage Lockout
V
DD33
Undervoltage Lockout
Hysteresis
V
DD33
Supply Input Operating Range
Regulator Output Voltage
Regulator Output Short-Circuit
Current
V
DD25
Regulator Output Voltage
Regulator Output Short-Circuit
Current
t
INIT
Initialization Time
V
PWR
= V
DD33
4.5V ≤ V
PWR
≤ 15V
V
PWR
= 4.5V, V
DD33
= 0V
3.13V ≤ V
DD33
≤ 3.47V
V
PWR
= V
DD33
= 3.47V, V
DD25
= 0V
Time from V
IN
applied until the TON_DELAY timer
starts
V
REF
= V
REFP
– V
REFM
, 0 < I
REFP
< 100µA
(Note 4)
Differential Voltage:
V
IN_ADC
= (V
SENSEPn
– V
SENSEMn
)
Single-Ended Voltage: V
SENSEMn
Current Sense Input Range
Single-Ended Voltage: I
SENSEPn
, I
SENSEMn
Differential Current Sense Voltage:
V
IN_ADC
= (I
SENSEPn
– I
SENSEMn
)
N_ADC
Voltage Sense Resolution (Note 5)
0V ≤ V
IN_ADC
≤ 6V, READ_VOUT
l
l
l
l
l
l
l
l
l
l
ELECTRICAL CHARACTERISTICS
Power Supply Characteristics
CONDITIONS
V
DD33
Floating
4.5V ≤ V
PWR
≤ 15V, V
DD33
Floating
3.13V ≤ V
DD33
≤ 3.47V, V
PWR
= V
DD33
V
DD33
Ramping Up, V
PWR
= V
DD33
l
l
l
l
MIN
4.5
TYP
MAX
15
UNITS
V
mA
mA
V
mV
10
10
2.25
2.55
120
3.13
3.13
50
2.35
30
3.26
90
2.5
55
30
13
13
2.8
3.47
3.47
140
2.6
80
V
V
mA
V
mA
ms
Voltage Reference Characteristics
V
REF
Output Voltage (Note 3)
Temperature Coefficient
Hysteresis
ADC Characteristics
V
IN_ADC
Voltage Sense Input Range
0
–0.1
–0.1
–170
122
6
0.1
6
170
V
V
V
mV
µV/LSB
Rev. B
1.220
1.232 1.244
3
100
V
ppm/°C
ppm
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