FEATURES
n
LTC3882
Dual Output PolyPhase
Step-Down DC/DC Voltage Mode Controller
with Digital Power System Management
DESCRIPTION
The
LTC
®
3882
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 LTC3882s can operate in parallel for 2-, 3-, 4-,
6- or 8-phase operation.
LTC3882 system configuration and monitoring is supported
by the
LTpowerPlay™
software tool. The device’s serial
interface can be used to read back input voltage, output
voltage and current, temperature and fault status. A wide
range of 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 programmed using external
configuration resistors.
L,
LT, LTC, LTM, Linear Technology,the Linear logo and PolyPhase are registered trademarks
and LTpowerPlay is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 5396245, 5859606,
6144194, 6937178, 7420359 and 7000125.
n
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PMBus/I
2
C Compliant Serial Interface
– Monitor Voltage, Current, Temperature and Faults
– Digitally Programmable Voltage, Current Limit,
Soft-Start/Stop, Sequencing, Margining, AVP
and UV/OV Thresholds
3V ≤ VINSNS ≤ 38V, 0.5V ≤ V
OUT
≤ 5.25V
±0.5% Output Voltage Accuracy
Programmable PWM Frequency or External Clock
Synchronization from 250kHz to 1.25MHz
Accurate PolyPhase
®
Current Sharing
Internal EEPROM with Fault Logging
IC Supply Range: 3V to 13.2V
Resistor or Inductor DCR Current Sensing
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
Industrial/Telecom/ATE Systems
TYPICAL APPLICATION
V
IN
7V TO 13.2V
+
V
CC
VINSNS V
SENSE0
FB0
LTC3882
SDA
SCL
TO/FROM
MCU
ALERT
RUN0
RUN1
WP
GPIO0
GPIO1
SHARE_CLK
SYNC
I
AVG0
I
AVG1
I
AVG_GND
GND
PWM1
TSNS1
V
SENSE0–
COMP0
COMP1
PWM0
TSNS0
I
SENSE0+
I
SENSE0–
V
SENSE1+
I
SENSE1–
I
SENSE1+
FDMF5820A
PWM
V
IN
SW
V
OUT
1V
80A
92
91
90
89
EFFICIENCY (%)
88
87
86
85
84
83
82
Efficiency and Power Loss vs
Load Current
13
11
9
7
5
V
IN
= 12V
V
OUT
= 1V
SYNC = 500kHz
0
10
20
30 40 50 60
LOAD CURRENT (A)
70
80
3
1
POWERLOSS (W)
GND
TO/FROM
EXTERNAL DEVICES
TO/FROM OTHER
OTHER PHASES
V
IN
FDMF5820A
PWM
GND
81
SW
80
3882 TA01b
INDUCTORS: COOPER FP1007R1-R22
SOME DETAILS OMITTED FOR CLARITY
3882 TA01a
3882f
For more information
www.linear.com/LTC3882
1
LTC3882
TABLE OF CONTENTS
Features .............................................................1
Applications ........................................................1
Typical Application ................................................1
Description..........................................................1
Absolute Maximum Ratings ......................................4
Order Information ..................................................4
Electrical Characteristics .........................................4
Pin Configuration ..................................................4
Typical Performance Characteristics ...........................8
Pin Functions ..................................................... 11
Block Diagram.................................................... 13
Test Circuit ........................................................ 14
Timing Diagram .................................................. 14
Operation.......................................................... 14
Overview .....................................................................14
Main Control Loop....................................................... 15
Power-Up and Initialization.......................................... 17
Soft-Start .................................................................... 18
Time-Based Output Sequencing .................................. 18
Output Ramping Control ............................................. 18
Voltage-Based Output Sequencing .............................. 18
Output Disable............................................................. 18
Minimum Output Disable Times .................................. 19
Output Short Cycle ...................................................... 19
Light Load Current Operation ...................................... 19
Switching Frequency and Phase ................................. 19
PolyPhase Load Sharing .............................................20
Active Voltage Positioning...........................................20
Input Supply Monitoring .............................................20
Output Voltage Sensing and Monitoring .....................20
Output Current Sensing and Monitoring .....................21
External and Internal Temperature Sense....................21
Resistor Configuration Pins ........................................21
Internal EEPROM with CRC .........................................22
Fault Detection ............................................................22
Input Supply Faults .....................................................22
Hardwired PWM Response to V
OUT
Faults ..................22
Power Good Indication ................................................23
Hardwired PWM Response to I
OUT
Faults ...................23
Hardwired PWM Response to Temperature Faults ......23
Hardwired PWM Response to Timing Faults...............23
External Faults.............................................................24
Fault Handling .............................................................24
Status Registers and
ALERT
Masking .........................24
Mapping Faults to
GPIO
Pins .......................................26
Other GPIO Uses .........................................................26
Fault Logging...............................................................26
Factory Default Operation ...........................................29
Serial Interface ............................................................30
Serial Bus Addressing .................................................30
Serial Bus Timeout ......................................................34
Serial Communication Errors ......................................34
PMBus Command Summary ................................... 35
PMBus Commands ......................................................35
Data Formats ...............................................................35
Applications Information ....................................... 40
Efficiency Considerations ............................................40
PWM Frequency and Inductor Selection .....................40
Power MOSFET Selection............................................41
MOSFET Driver Selection ............................................42
Using PWM Protocols .................................................42
C
IN
Selection ...............................................................43
C
OUT
Selection.............................................................44
Feedback Loop Compensation ....................................44
PCB Layout Considerations .........................................46
Output Current Sensing ...............................................47
Output Voltage Sensing ...............................................49
Soft-Start and Stop .....................................................49
Time-Based Output Sequencing and Ramping............50
Voltage-Based Output Sequencing ..............................51
Using Output Voltage Servo ........................................52
Using AVP ...................................................................52
PWM Frequency Synchronization ...............................53
PolyPhase Operation and Load Sharing ......................54
External Temperature Sense .......................................56
Resistor Configuration Pins ........................................58
Internal Regulator Outputs ..........................................59
IC Junction Temperature .............................................60
Derating EEPROM Retention at Temperature ..............60
Configuring Open-Drain Pins ......................................60
PMBus Communication and Command Processing ....61
Status and Fault Log Management ..............................62
LTpowerPlay – An Interactive Digital Power GUI .........63
Interfacing to the DC1613............................................63
Design Example...........................................................64
PMBus COMMAND DETAILS .................................... 66
Addressing and Write Protect ..........................................66
PAGE ...........................................................................66
PAGE_PLUS_WRITE ...................................................66
PAGE_PLUS_READ .....................................................67
WRITE_PROTECT .......................................................67
MFR_ADDRESS ..........................................................68
MFR_RAIL_ADDRESS ................................................68
General Device Configuration ..........................................68
PMBUS_REVISION......................................................68
CAPABILITY ................................................................68
MFR_CONFIG_ALL_LTC3882 .....................................69
On, Off and Margin Control ..............................................69
ON_OFF_CONFIG .........................................................69
OPERATION .................................................................70
3882f
2
For more information
www.linear.com/LTC3882
LTC3882
TABLE OF CONTENTS
MFR_RESET ................................................................70
PWM Configuration .........................................................71
FREQUENCY_SWITCH .................................................71
MFR_PWM_CONFIG_LTC3882...................................72
MFR_CHAN_CONFIG_LTC3882 ..................................73
MFR_PWM_MODE_LTC3882 ..................................... 74
Input Voltage and Limits ..................................................75
VIN_ON .......................................................................75
VIN_OFF ......................................................................75
VIN_OV_FAULT_LIMIT ................................................75
VIN_UV_WARN_LIMIT ................................................75
Output Voltage and Limits ...............................................76
VOUT_MODE ...............................................................76
VOUT_COMMAND .......................................................76
MFR_VOUT_MAX ........................................................76
VOUT_MAX .................................................................77
MFR_VOUT_AVP .........................................................77
VOUT_MARGIN_HIGH.................................................77
VOUT_MARGIN_LOW .................................................77
VOUT_OV_FAULT_LIMIT .............................................77
VOUT_OV_WARN_LIMIT .............................................78
VOUT_UV_WARN_LIMIT .............................................78
VOUT_UV_FAULT_LIMIT .............................................78
Output Current and Limits ...............................................79
IOUT_CAL_GAIN .........................................................79
MFR_IOUT_CAL_GAIN_TC .........................................79
IOUT_OC_FAULT_LIMIT ..............................................79
IOUT_OC_WARN_LIMIT..............................................79
Output Timing, Delays, and Ramping ..............................80
MFR_RESTART_DELAY ..............................................80
TON_DELAY ................................................................80
TON_RISE ...................................................................80
TON_MAX_FAULT_LIMIT ...........................................81
VOUT_TRANSITION_RATE ..........................................81
TOFF_DELAY ...............................................................81
TOFF_FALL ..................................................................81
TOFF_MAX_WARN_LIMIT ..........................................81
External Temperature and Limits .....................................82
MFR_TEMP_1_GAIN ....................................................82
MFR_TEMP_1_OFFSET................................................82
OT_FAULT_LIMIT ........................................................82
OT_WARN_LIMIT ........................................................82
UT_FAULT_LIMIT ........................................................83
Status Reporting ..............................................................83
STATUS_BYTE ............................................................83
STATUS_WORD...........................................................84
STATUS_VOUT ............................................................84
STATUS_IOUT .............................................................85
STATUS_INPUT ...........................................................85
STATUS_TEMPERATURE ............................................85
STATUS_CML ..............................................................86
STATUS_MFR_SPECIFIC.............................................86
MFR_PADS_LTC3882 .................................................87
MFR_COMMON ...........................................................87
Telemetry .........................................................................88
READ_VIN ...................................................................88
CLEAR_FAULTS ..........................................................88
MFR_VIN_PEAK ..........................................................89
READ_VOUT ................................................................89
MFR_VOUT_PEAK .......................................................89
READ_IOUT .................................................................89
MFR_IOUT_PEAK ........................................................89
READ_POUT................................................................89
READ_TEMPERATURE_1 ............................................90
MFR_TEMPERATURE_1_PEAK ...................................90
READ_TEMPERATURE_2 ............................................90
MFR_TEMPERATURE_2_PEAK ..................................90
READ_DUTY_CYCLE ...................................................90
READ_FREQUENCY.....................................................90
MFR_CLEAR_PEAKS ..................................................90
Fault Response and Communication................................91
VIN_OV_FAULT_RESPONSE .......................................91
VOUT_OV_FAULT_RESPONSE ....................................92
VOUT_UV_FAULT_RESPONSE ....................................92
IOUT_OC_FAULT_RESPONSE .....................................93
OT_FAULT_RESPONSE................................................94
UT_FAULT_RESPONSE................................................94
MFR_OT_FAULT_RESPONSE ......................................94
TON_MAX_FAULT_RESPONSE ...................................95
MFR_RETRY_DELAY...................................................95
SMBALERT_MASK ......................................................96
MFR_GPIO_PROPAGATE_LTC3882 ............................97
MFR_GPIO_RESPONSE ..............................................97
EEPROM User Access ......................................................98
MFR_FAULT_LOG........................................................98
MFR_FAULT_LOG_CLEAR ..........................................98
STORE_USER_ALL .....................................................99
RESTORE_USER_ALL.................................................99
MFR_COMPARE_USER_ALL ......................................99
MFR_FAULT_LOG_STORE ..........................................99
MFR_EE_xxxx.............................................................99
USER_DATA_0x ..........................................................99
Unit Identification...........................................................100
MFR_ID .....................................................................100
MFR_MODEL.............................................................100
MFR_SERIAL ............................................................100
Typical Applications ............................................101
Package Description ...........................................103
Typical Application .............................................104
Related Parts ....................................................104
3882f
For more information
www.linear.com/LTC3882
3
LTC3882
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
V
SENSE0+
V
SENSE0–
V
SENSE1+
I
SENSE0+
I
SENSE0–
I
SENSE1–
I
SENSE1+
V
OUT1_CFG
I
AVG0
I
AVG1
30 FB1
29 COMP1
28 BG1/EN1
27 TG1/PWM1
(V
SENSE1–
)
41
GND
26 V
CC
25 V
DD33
24 SHARE_CLK
23 WP
22 V
DD25
21 PHAS_CFG
11 12 13 14 15 16 17 18 19 20
FREQ_CFG
V
OUT0_CFG
ALERT
GPIO0
GPIO1
RUN0
RUN1
ASEL0
ASEL1
FB0
COMP0 1
TSNS0 2
TSNS1 3
VINSNS 4
I
AVG_GND
5
BGO/EN0 6
TGO/PWM0 7
SYNC 8
SCL 9
SDA 10
V
CC
Supply Voltage .................................... –0.3V to 15V
VINSNS Voltage ......................................... –0.3V to 40V
V
SENSE0 –
...................................................... –0.3V to 1V
V
SENSEn+
, I
SENSEn+
, I
SENSEn –
........................ –0.3V to 6V
V
DD33
, FBn, COMPn, TSNSn,
I
AVGn
, I
AVG_GND
......................................... –0.3V to 3.6V
SYNC,
GPIOn,
WP, PWMn, ENn,
SHARE_CLK.............................................. –0.3V to 3.6V
SCL, SDA, RUNn,
ALERT
........................... –0.3V to 5.5V
V
DD25
, ASELn, V
OUTn_CFG
, FREQ_CFG,
PHAS_CFG .............................................. –0.3V to 2.75V
Operating Junction Temperature Range
(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.
40 39 38 37 36 35 34 33 32 31
UJ PACKAGE
40-LEAD (6mm
×
6mm) PLASTIC QFN
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#PBF
LTC3882IUJ#PBF
TAPE AND REEL
LTC3882EUJ#TRPBF
LTC3882IUJ#TRPBF
PART MARKING*
LTC3882UJ
LTC3882UJ
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.
Consult LTC Marketing for information on nonstandard lead based finish parts.
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/
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
DD33
= Internal LDO
V
CC
= V
DD33
(Note 6)
V
DD33
Rising
Hysteresis
l
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
70
3882f
4
For more information
www.linear.com/LTC3882
LTC3882
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
V
DD33
I
DD33
PARAMETER
Internal V
DD33
Voltage
V
DD33
Current Limit
CONDITIONS
V
CC
≥ 4.5V
V
DD33
= 2.8V
V
DD33
= 0V
2.25
l
ELECTRICAL CHARACTERISTICS
MIN
3.2
TYP
3.3
85
40
2.5
95
MAX
3.4
UNITS
V
mA
mA
V
DD33
Linear Regulator
V
DD25
Linear Regulator
V
DD25
I
DD25
VINSNS
R
VINSNS
V
OUT_R0
Internal V
DD25
Voltage
V
DD25
Current Limit
V
IN
Sense Voltage Range
VINSNS Input Resistance
Range 0 Maximum V
OUT
Range 0 Set Point Accuracy (Note 7)
Range 0 Resolution
Range 0 LSB Step Size
V
OUT_R1
Range 1 Maximum V
OUT
Range 1 Set Point Accuracy (Note 7)
Range 1 Resolution
Range 1 LSB Step Size
I
VSENSE
V
LINEREG
AVP
V
SENSE
Input Current
V
CC
Line Regulation, No Output Servo
AVP Set Accuracy, ∆V
OUT
Resolution
LSB Step Size
A
V(OL)
SR
f
0dB
I
COMP
R
VSFB
V
ISENSE
I
ISENSE
I
AVG_VOS
V
SIOS
f
SYNC
N
VON
V
ON_TOL
N
UVOV
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
3
278
0.6V ≤ V
OUT
≤ 5V
0.6V ≤ V
OUT
≤ 5V
5.25
±0.2
12
1.375
2.65
±0.2
12
0.6875
235
–335
–0.02
l
38
V
kΩ
V
%
%
Bits
mV
V
%
%
Bits
mV
µA
µA
l
–0.5
0.5
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 (20%) to 12mV (80%)
IOUT_OC_WARN_LIMIT at 15mV
l
–0.5
0.5
0.02
–96
5
0.5
87
9.5
30
%/V
mV
Bits
%
dB
V/µs
MHz
mA
mA
–118
Sourcing
Sinking
Range 0
Range 1
0V ≤ V
PIN
≤ 5.5V
Referred to I
SENSE
Inputs
l
l
l
–2.6
34
52
37
–1
–600
–800
–10
8
143
67
49
±70
±0.1
±175
±300
1
650
700
10
83
61
kΩ
kΩ
mV
µA
µV
µV
µV
µV
%
Bits
mV
I
AVG
Current Sense Offset
Slave Current Sharing Offset
SYNC Frequency Accuracy
Input ON/OFF Resolution
LSB Step Size
Input ON/OFF Threshold Accuracy
Resolution
Referred to I
SENSE
Inputs
l
250kHz ≤ f
SYNC
≤ 1.25MHz
l
Input Voltage Supervisor
15V ≤ V
IN_ON
≤ 35V
l
–2
9
2
%
Bits
3882f
Output Voltage Supervisors
For more information
www.linear.com/LTC3882
5
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