LTC2972
2-Channel PMBus Power System Manager
Featuring Programmable Power Good Outputs
FEATURES
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DESCRIPTION
The
LTC
®
2972
is a 2-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
voltage and temperature threshold limits for two 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 two output voltages, two
output currents, two external temperatures, input voltage
and current, and die temperature. Input power, energy,
and output power are 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 ADI 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, 8648623 and 8920026.
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Sequence, Trim, Margin and Supervise Two
Power Supplies
Manage Faults, Monitor Telemetry
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 Supervisors per Channel
Coordinate Sequencing and Fault Management
Across Multiple ADI PSM Devices
Automatic Fault Logging to Internal EEPROM
Operate Autonomously Without Additional Software
Configurable Power Good Output Pins
Accurate Monitoring of Output Voltage, Output
Current, Temperature, and Input Voltage and Current
1.8V to 3.3V I
2
C/SMBus Serial Interface
Connect Directly to Regulator IMON Pins
Can Be Powered from 3.3V, or 4.5V to 15V
Available in 44-Pin 6mm × 7mm QFN Package
APPLICATIONS
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Computers and Network Servers
Industrial Test and Measurement
High Reliability Systems
Video and Medical Imaging
TYPICAL APPLICATION
Closed-Loop Servo Error vs Temperature
DC
IN
IN
IBC
EN
OUT
4.5V ≤ V
IBUS
≤ 15V
V
PWR
*
I
IN_SNSP
I
IN_SNSM
V
IN_SNS
AUXFAULTB
CONTROL
FAULT
PWRGD
V
IN
V
OUT
DC/DC
CONVERTER
RUN
V
FB
R10
R30
R
SNS
I
SENSEP0
I
SENSEM0
V
SENSEP0
R20
LOAD
V
SENSEM0
V
DAC0
V
OUT_EN0
PG0
T
SENSE0
V
SENSEM1
V
DAC1
V
OUT_EN1
PG1
T
SENSE1
2972 TA01a
0.25
ALERTB
SCL
SDA
V
DD33
*
V
DDIO
R
SNS
PMBus
INTERFACE
80 PARTS SOLDERED DOWN
0.20 V = 1.0V
IN
0.15
ERROR (% OF READING)
0.10
0.05
0.00
–0.05
–0.10
–0.15
–0.20
I
SENSEP1
I
SENSEM1
LTC2972
V
SENSEP1
V
IN
V
OUT
DC/DC
CONVERTER
V
FB
RUN
LOAD
R20
R30
R10
NOTE: SOME DETAILS
OMITTED FOR CLARITY
*LTC2972 MAY ALSO BE
POWERED DIRECTLY FROM
AN EXTERNAL 3.3V SUPPLY
–0.25
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
2972 TA01b
2972fa
For more information
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1
LTC2972
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
PMBus Timing Diagram........................................................ 11
Typical Performance Characteristics ........................................ 12
Pin Functions .................................................................... 16
Block Diagram................................................................... 18
Operation......................................................................... 19
LTC2972 Operation Overview .............................................................19
EEPROM ....................................................................................... 20
AUXFAULTB ....................................................................................... 20
RESETB.............................................................................................. 20
V
DDIO .....................................................................................................................20
PMBus Serial Digital Interface .......................................................... 21
PMBus .......................................................................................... 21
Device Address ............................................................................ 21
Processing Commands ................................................................ 21
Addressing and Write Protect ........................................................... 31
PAGE ............................................................................................ 31
WRITE_PROTECT ........................................................................ 32
WRITE PROTECT Pin ................................................................... 32
MFR_PAGE_FF_MASK ................................................................. 33
MFR_I2C_BASE_ADDRESS ........................................................ 33
MFR_COMMAND_PLUS .............................................................. 33
MFR_DATA_PLUS0 and MFR_DATA_PLUS1 .............................. 33
MFR_STATUS_PLUS0, and MFR_STATUS_PLUS1 .................... 33
Reading Fault Log Using Command Plus and MFR_DATA_PLUS0 .
34
Reading Energy Using MFR_COMMAND_PLUS and MFR_DATA_
PLUS0 .......................................................................................... 35
Peek Operation Using MFR_DATA_PLUS0.................................. 35
Enabling and Disabling Poke Operations ..................................... 35
Poke Operation Using Mfr_data_plus0 ....................................... 36
Command Plus Operations Using MFR_DATA_PLUS1 ............... 36
On/Off Control, Margining and Configuration ................................... 36
OPERATION .................................................................................. 37
ON_OFF_CONFIG ......................................................................... 38
MFR_CONFIG_LTC2972 .............................................................. 38
Cascade Sequence ON with Time-Based Sequence OFF ............. 40
MFR_CONFIG2_LTC2972 .............................................................41
MFR_CONFIG3_LTC2972 .............................................................41
Tracking Supplies On and Off ...................................................... 42
Tracking Implementation ............................................................. 42
MFR_CONFIG_ALL_LTC2972 ..................................................... 44
Programming User EEPROM Space .................................................. 46
STORE_USER_ALL and RESTORE_USER_ALL .......................... 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................................................................. 49
INPUT Current and ENERGY .............................................................. 49
Energy Measurement and Reporting ........................................... 49
MFR_EIN ..................................................................................... 49
MFR_EIN_CONFIG ....................................................................... 50
MFR_IIN_CAL_GAIN ....................................................................51
MFR_IIN_CAL_GAIN_TC ..............................................................51
MFR_CLEAR_ENERGY .................................................................51
Output Voltage Commands and Limits.............................................. 52
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 .................................................................... 53
MFR_VOUT_DISCHARGE_THRESHOLD ...................................... 53
MFR_DAC_STARTUP................................................................... 53
MFR_DAC..................................................................................... 53
Output CURRENT Commands and Limits ......................................... 54
IOUT_CAL_GAIN and IOUT_CAL_OFFSET .................................. 54
IOUT_OC_WARN_LIMIT .............................................................. 54
MFR_IOUT_CAL_GAIN_TC .......................................................... 54
External Temperature Commands and Limits ................................... 55
OT_FAULT_LIMIT, OT_WARN_LIMIT, UT_WARN_LIMIT and
UT_FAULT_LIMIT ......................................................................... 56
MFR_TEMP_1_GAIN and MFR_TEMP_1_OFFSET ....................... 56
MFR_T_SELF_HEAT, MFR_IOUT_CAL_GAIN_TAU_INV and MFR_
IOUT_CAL_GAIN_THETA ............................................................. 56
Sequencing Timing Limits and Clock Sharing................................... 58
TON_DELAY, TON_RISE, TON_MAX_FAULT_LIMIT and TOFF_
DELAY .......................................................................................... 58
MFR_RESTART_DELAY ............................................................... 59
Clock Sharing ............................................................................... 59
Watchdog Timer and Power Good..................................................... 59
MFR_PG_CONFIG ........................................................................ 60
MFR_PG_GPO ............................................................................. 62
MFR_PWRGD_EN ........................................................................ 62
MFR_POWERGOOD_ASSERTION_DELAY .................................. 62
Watchdog Operation .................................................................... 63
MFR_WATCHDOG_T_FIRST and MFR_WATCHDOG_T ............... 63
Fault Responses ................................................................................ 63
Clearing Latched Faults ............................................................... 64
VOUT_OV_FAULT_RESPONSE and VOUT_UV_FAULT_RESPONSE
64
OT_FAULT_RESPONSE, UT_FAULT_RESPONSE, VIN_OV_FAULT_
RESPONSE and VIN_UV_FAULT_RESPONSE.............................. 65
TON_MAX_FAULT_RESPONSE ................................................... 65
MFR_RETRY_DELAY ................................................................... 66
MR_RETRY_COUNT .................................................................... 66
Shared External Faults....................................................................... 67
MFR_FAULTB0_PROPAGATE and MFR_FAULTB1_PROPAGATE 67
MFR_FAULTB0_RESPONSE and MFR_FAULTB1_RESPONSE ... 67
Fault Warning and Status .................................................................. 68
2972fa
2
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LTC2972
TABLE OF CONTENTS
CLEAR_FAULTS ........................................................................... 68
STATUS_BYTE ............................................................................. 69
STATUS_WORD ........................................................................... 69
STATUS_VOUT ............................................................................. 70
STATUS_IOUT .............................................................................. 70
STATUS_INPUT............................................................................ 70
STATUS_TEMPERATURE ............................................................. 71
STATUS_CML............................................................................... 71
STATUS_MFR_SPECIFIC ............................................................. 72
MFR_PADS .................................................................................. 72
MFR_COMMON............................................................................ 73
MFR_STATUS_2 ...........................................................................74
MFR_FIRST_FAULT ......................................................................74
Telemetry ........................................................................................... 75
READ_VIN .................................................................................... 75
READ_IIN ..................................................................................... 75
READ_PIN .................................................................................... 75
READ_VOUT ................................................................................. 75
READ_IOUT.................................................................................. 76
MFR_IIN_PEAK ............................................................................ 76
READ_TEMPERATURE_2 ............................................................ 76
READ_POUT ................................................................................ 77
MFR_READ_IOUT ........................................................................ 77
MFR_IOUT_SENSE_VOLTAGE ..................................................... 78
MFR_VIN_PEAK........................................................................... 78
MFR_TEMPERATURE_1_MIN ...................................................... 79
Fault Logging ..................................................................................... 79
Fault Log Operation...................................................................... 79
MFR_FAULT_LOG_STORE........................................................... 80
MFR_FAULT_LOG_RESTORE ...................................................... 80
MFR_FAULT_LOG_CLEAR ........................................................... 80
MFR_FAULT_LOG_STATUS ......................................................... 80
MFR_FAULT_LOG ........................................................................ 80
MFR_FAULT_LOG Read Example ................................................ 83
Identification/Information ................................................................. 88
CAPABILITY ................................................................................. 88
PMBUS_REVISION ...................................................................... 88
MFR_SPECIAL_ID ....................................................................... 88
MFR_SPECIAL_LOT .................................................................... 88
MFR_INFO.................................................................................... 89
User Scratchpad ................................................................................ 89
USER_DATA_00, USER_DATA_01, USER_DATA_02, USER_
DATA_03, USER_DATA_04 and MFR_LTC_RESERVED_2 ......... 89
Applications Information ...................................................... 90
Overview ............................................................................................ 90
Powering the LTC2972 ...................................................................... 90
Setting Command Register Values .................................................... 90
MEASURING INPUT CURRENT ......................................................... 90
MEASURING INPUT VOLTAGE .......................................................... 92
MEASURING INPUT POWER ............................................................. 92
Measuring INPUT ENERGY ................................................................ 92
Sequence, Servo, Margin and Restart Operations ............................ 92
Command Units On or Off ........................................................... 92
On Sequencing ............................................................................. 93
On State Operation....................................................................... 93
Servo Modes ................................................................................ 93
DAC Modes .................................................................................. 93
Margining ..................................................................................... 94
Off Sequencing ............................................................................ 94
V
OUT
Off Threshold Voltage ......................................................... 94
Automatic Restart via MFR_RESTART_DELAY Command and
CONTROL Pin ............................................................................... 94
Fault Management ............................................................................. 95
Output Overvoltage and Undervoltage Faults .............................. 95
Output Overvoltage, Undervoltage, and Overcurrent Warnings.. 95
Configuring the AUXFAULTB Output............................................ 95
Multi-Channel Fault Management ................................................ 95
Interconnect Between Multiple ADI POWER MANAGERS................. 97
Application Circuits ........................................................................... 98
Trimming and Margining DC/DC Converters with External
Feedback Resistors ...................................................................... 98
Four-Step Resistor Selection Procedure for DC/DC Converters
with External Feedback Resistors................................................ 98
Trimming and Margining DC/DC Converters with a TRIM Pin..... 99
Two-Step Resistor and DAC Full-Scale Voltage Selection
Procedure for DC/DC Converters with a TRIM Pin ...................... 99
Measuring Output with a Sense Resistor .................................. 100
Measuring Output with Inductor DCR ....................................... 100
Single Phase Design Example.................................................... 100
Measuring Multiphase Currents .................................................101
Measuring Output Current in Buffered IMON Telemetry Mode ..101
LT3086 IMON Design Example ...................................................101
Anti-Aliasing Filter Considerations ............................................ 102
Sensing Negative Voltages ........................................................ 102
Connecting the DC1613 USB to I
2
C/SMBus/PMBus Controller to
the LTC2972 in System .............................................................. 103
Accurate DCR Temperature Compensation ..................................... 105
LTpowerPlay: An Interactive GUI for Power Managers ................... 106
PCB Assembly and Layout Suggestions ......................................... 108
Bypass Capacitor Placement ..................................................... 108
Exposed Pad Stencil Design ...................................................... 108
PCB Board Layout ...................................................................... 108
Unused ADC Sense Inputs ......................................................... 108
Design Checklist .............................................................................. 109
I
2
C .............................................................................................. 109
Output Enables ........................................................................... 109
V
IN
Sense ................................................................................... 109
Input Current Sense ................................................................... 109
External Temperature Sense ...................................................... 109
Logic Signals.............................................................................. 109
Unused Inputs ............................................................................ 109
DAC Outputs............................................................................... 109
Package Description ..........................................................110
Revision History ...............................................................111
Typical Application ............................................................112
Related Parts ...................................................................112
2972fa
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3
LTC2972
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PIN CONFIGURATION
TOP VIEW
AUXFAULTB
V
SENSEM1
V
OUT_EN0
V
OUT_EN1
V
SENSEP1
I
SENSEM1
35
34 I
SENSEP1
33 V
SENSEM0
32 V
SENSEP0
31 I
SENSEM0
30 I
SENSEP0
45
GND
29 REFM
28 REFP
27 ASEL1
26 ASEL0
25 V
DDIO
24 CONTROL1
23 CONTROL0
13
SHARE_CLK
14
PG0
15
PG1
16 17
WDI/RESETB
FAULTB0
18
FAULTB1
19 20
WP
SDA
21
SCL
22
ALERTB
I
IN_SNSM
I
IN_SNSP
V
DAC1
V
DAC0
38
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, PG[1:0], V
DDIO
................... –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[1:0]
.............................................. –0.3V to 6V
V
SENSEM[1:0]
............................................. –0.3V to 6V
I
SENSEP[1:0]
............................................... –0.3V to 6V
I
SENSEM[1:0]
.............................................. –0.3V to 6V
V
OUT_EN[1:0]
, AUXFAULTB ...................... –0.3V to 15V
V
DAC[1:0]
................................................... –0.3V to 6V
T
SENSE[1:0]
............................................. –0.3V to 3.6V
I
IN_SNSP
, I
IN_SNSM
.................................. –0.3V to 15V
Operating Junction Temperature Range:
LTC2972C ................................................ 0°C to 70°C
LTC2972I ........................................... –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.
44
V
IN_SNS_CAP
1
GND 2
DNC 3
V
IN_SNS
4
V
PWR
5
V
DD33
6
V
DD33
7
V
DD25
8
V
DD25
9
T
SENSE0
10
T
SENSE1
11
PWRGD 12
43
42
41
40 39
37 36
UJF PACKAGE
44-LEAD (6mm × 7mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JCtop
= 13.57°C/W,
θ
JCbottom
= 2.82°C/W
EXPOSED PAD (PIN 45) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
TUBE
LTC2972CUJF#PBF
LTC2972IUJF#PBF
TAPE AND REEL
LTC2972CUJF#TRPBF
LTC2972IUJF#TRPBF
http://www.linear.com/product/LTC2972#orderinfo
PART MARKING*
LTC2972UJF
LTC2972UJF
PACKAGE DESCRIPTION
44-Lead (6mm × 7mm) Plastic QFN
44-Lead (6mm × 7mm) Plastic QFN
JUNCTION TEMPERATURE RANGE
0°C to 70°C
–40°C to 105°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.
4
2972fa
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LTC2972
ELECTRICAL CHARACTERISTICS
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
V
DDIO
R
IN
V
REF
Initialization Time
V
DDIO
Input Operating Range
V
DDIO
Input Resistance
Output Voltage (Note 3)
Temperature Coefficient
Hysteresis
ADC Characteristics
V
IN_ADC
Voltage Sense Input Range
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
)
Mfr_config_imon_sel = 0
Mfr_config_imon_sel = 1
N_ADC
Voltage Sense Resolution
Current Sense Resolution
with IOUT_CAL_GAIN = 1Ω
0V ≤ V
IN_ADC
≤ 6V, READ_VOUT
0mV ≤ |V
IN_ADC
| < 16mV (Note 5)
16mV ≤ |V
IN_ADC
| < 32mV
32mV ≤ |V
IN_ADC
| < 63.9mV
63.9mV ≤ |V
IN_ADC
| < 127.9mV
127.9mV ≤ |V
IN_ADC
|
Voltage Sense Inputs V
IN_ADC
≥ 1V
Voltage Sense Inputs 0 ≤ V
IN_ADC
≤ 1V
l
l
l
l
l
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
DDIO,
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)
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
Power Supply Characteristics
6.7
6.7
2.25
2.55
120
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
l
l
l
l
l
l
9
9
2.8
3.13
3.13
75
2.35
30
3.26
90
2.5
55
30
1.62
53
1.216
68.8
3.47
3.47
140
2.6
80
V
V
mA
V
mA
ms
3.6
86
V
kΩ
V
ppm/°C
ppm
0 ≤ V
VDDIO
≤ 3.6V
V
REF
= V
REFP
– V
REFM
, 0 < I
REFP
< 100µA
(Note 4)
l
Voltage Reference Characteristics
l
1.228 1.240
3
100
0
–0.1
–0.1
6
0.1
6
V
V
V
l
l
–170
–0.1
122
15.625
31.25
62.5
125
250
170
6
mV
V
µV/LSB
µA/LSB
µA/LSB
µA/LSB
µA/LSB
µA/LSB
TUE_ADC_
VOLT_SNS
Total Unadjusted Error (Note 3)
±0.25 % of Reading
±2.5
mV
2972fa
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