POWER LOSS (W)
LTC3880/LTC3880-1
Dual Output PolyPhase
Step-Down DC/DC Controller with
Digital Power System Management
FEATURES DESCRIPTION
2
n
PMBus/I C Compliant Serial Interface
The LTC 3880/LTC3880-1 are dual, PolyPhase DC/DC
n
Telemetry Read Back includes V , I , V , I ,
synchronous step-down switching regulator controllers
IN IN OUT OUT
2
Temperature and Faults
with an I C-based PMBus compliant serial interface.
n
Programmable Voltage, Current Limit, Digital
The controllers use a constant frequency, current mode
Soft-Start/Stop, Sequencing, Margining, OV/UV
architecture that is supported by LTpowerPlay software
and Frequency Synchronization (250kHz to 1MHz)
development tool with graphical user interface (GUI).
n
0.5% Output Voltage Accuracy Over Temperature
Switching frequency, output voltage, and device address
n
Integrated 16-Bit ADC
can be programmed using external configuration resistors.
n
Internal EEPROM with ECC and Fault Logging
Parameters can be set via the digital interface or stored in
n
Integrated Powerful N-Channel MOSFET Gate Drivers
EEPROM. Voltage, current, internal/external temperature
Power Conversion
and fault status can be read back through the bus interface.
n
Wide V Range: 4.5V to 24V
IN The LTC3880 incorporates a 5V linear regulator while the
n
V Range: 0.5V to 5.4V (4V on V )
OUT OUT0 LTC3880-1 uses an external 5V supply for minimum power
n
Analog Current Mode Control Loop
loss. See comparison to LTC3887 below.
n
Supports Power-Up Into Pre-Biased Load
V Max Fast ADC Mode
OUT
n
Accurate PolyPhase Current Sharing for Up to 6 Phases
Start-Up Time V for 1 Parameter
OUT0/1
n
Available in a 40-Pin (6mm 6mm) QFN Package
LTC3887/LTC3887-1
35ms 5.5V/5.5V Yes
LTC3880/LTC3880-1
120ms 4V/5.4V No
APPLICATIONS
L, LT, LTC, LTM, PolyPhase, Burst Mode, Module, Linear Technology and the Linear logo
n
High Current Distributed Power Systems are registered trademarks and No R and LTpowerPlay are trademarks of Analog Devices,
SENSE
Inc. All other trademarks are the property of their respective owners. Protected by U.S. Patents
n
Telecom, Datacom and Storage Systems
including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258, 5408150, 7420359.
Licensed under U.S. Patent 7000125 and other related patents worldwide.
n
Intelligent Energy Efficient Power Regulation
TYPICAL APPLICATION
V
IN
1F
10F
Efficiency and Power Loss
V INTV
IN CC
vs Load Current
TG0 TG1
0.1F 0.1F 100 6
LTC3880
V = 12V
IN
BOOST0 BOOST1 90
1.0H 0.56H V V = 1.8V
V OUT1 OUT
OUT0
5
3.3V SW0 SW1 1.8V
80
20A
15A
2.15k 1.74k
BG0 BG1
70
4
0.2F 0.2F
PGND
60
+ +
I I
SENSEO SENSE1
50 3
+
I I
SENSEO SENSE1
530F
+ 40
V V
SENSEO SENSE1
2
V
SENSEO 30
TSNS0 TSNS1
+
20
10nF 10nF 530F 1
2200pF 2200pF
10
6.04k 4.99k
I I
THO TH1
0 0
0.01 0.1 1 10 100
SDA GPIO0
FAULT MANAGEMENT
LOAD CURRENT (A)
SCL GPIO1
SOME DETAILS OMITTED
PMBus
ALERT
FOR CLARITY
3880 TA01b
INTERFACE
RUN0
V
DD33
RUN1 V
DD25
TO/FROM SHARE_CLK 1F 1F
SYNC
OTHER LTC DEVICES
SGND
WP
WRITE PROTECT
3880 TA01a
3880fg
1
For more information www.linear.com/LTC3880
EFFICIENCY (%)LTC3880/LTC3880-1
TABLE OF CONTENTS
Features ..................................................... 1 Responses to Timing Faults ....................................27
Applications ................................................ 1 Responses to V OV Faults ....................................27
IN
Typical Application ........................................ 1 Responses to OT/UT Faults .....................................27
Description.................................................. 1 Overtemperature Fault ResponseInternal ......27
Table of Contents .......................................... 2 Overtemperature and Undertemperature
Absolute Maximum Ratings .............................. 4 Fault ResponseExternals ...............................27
Pin Configuration .......................................... 4 Responses to External Faults .................................27
Order Information .......................................... 4 Bus Timeout Failure ................................................28
2
Electrical Characteristics ................................. 5 Similarity Between PMBus, SMBus and I C
Typical Performance Characteristics .................. 10 2-Wire Interface ......................................................28
Pin Functions .............................................. 13 PMBus Serial Digital Interface ................................28
Block Diagram ............................................. 15 PMBus Command Summary ............................ 32
Operation................................................... 16 PMBus Commands .................................................32
Overview ................................................................. 16 *Data Format ..........................................................37
Main Control Loop .................................................. 16 Applications Information ................................ 38
EEPROM ................................................................. 17 Current Limit Programming ....................................38
+
Power Up and Initialization ..................................... 18 I and I Pins .........................................38
SENSE SENSE
Soft-Start ................................................................ 18 Low Value Resistor Current Sensing .......................39
Sequencing ............................................................. 19 Inductor DCR Current Sensing ................................40
Voltage-Based Sequencing ..................................... 19 Slope Compensation and Inductor Peak Current .... 41
Shutdown ............................................................... 19 Inductor Value Calculation ...................................... 41
Light Load Current Operation .................................20 Inductor Core Selection ..........................................42
Switching Frequency and Phase .............................20 Power MOSFET and Schottky Diode (Optional)
Output Voltage Sensing ..........................................21 Selection .................................................................42
Current Sensing ......................................................21 Variable Delay Time, Soft-Start and Output Voltage
Load Sharing ..........................................................22 Ramping .................................................................43
External/Internal Temperature Sense ......................22 Digital Servo Mode .................................................44
RCONFIG (Resistor Configuration) Pins ..................23 Soft Off (Sequenced Off) ........................................44
Fault Detection and Handling ..................................23 INTV Regulator ....................................................45
CC
Internal Memory with CRC and ECC ................... 24 Topside MOSFET Driver Supply (C , D ) ................46
B B
Serial Interface .......................................................25 Undervoltage Lockout .............................................46
Communication Failure ......................................25 C and C Selection ...........................................46
IN OUT
Device Addressing ..................................................25 Fault Conditions ...................................................... 47
Responses to V and I Faults ........................26 Open-Drain Pins .....................................................48
OUT OUT
Output Overvoltage Fault Response ...................26 Phase-Locked Loop and Frequency
Output Undervoltage Response .........................26 Synchronization ......................................................48
Peak Output Overcurrent Fault Response ...........26 Minimum On-Time Considerations..........................49
3880fg
2
For more information www.linear.com/LTC3880