FeaTures
n
LTC3883/LTC3883-1
Single Phase Step-Down
DC/DC Controller with Digital
Power System Management
DescripTion
The LTC
®
3883/LTC3883-1 are PolyPhase capable DC/DC
synchronous step-down switching regulator controllers
with a PMBus compliant serial interface. The controllers
use a constant frequency, current mode architecture that
is supported by the LTPowerPlay™ software development
tool with graphical user interface (GUI).
Switching frequency, output voltage, and device address
can be programmed using external configuration resistors.
Additionally, parameters can be set via the digital interface
or stored in on-chip EEPROM.
The LTC3883/LTC3883-1 can be configured for Burst
Mode
®
operation, discontinuous (pulse-skipping) mode or
continuous inductor current mode. The LTC3883 incorpo-
rates an internal 5V linear regulator while the LTC3883-1
uses an external 5V supply for minimum power loss.
The LTC3883/LTC3883-1 are available in a 32-lead 5mm
×
5mm QFN package.
L,
LT, LTC, LTM, OPTI-LOOP, PolyPhase, Burst Mode, µModule, Linear Technology and
the Linear logo are registered trademarks and LTpowerPlay, No R
SENSE
and UltraFast are
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Protected by U.S. Patents including 5481178, 5705919, 5929620, 6100678,
6144194, 6177787, 5408150, 6580258, 6304066, 7420359, Patent Pending.
PMBus/I
2
C Compliant Serial Interface
– Telemetry Read-Back Includes V
IN
, I
IN
, V
OUT
, I
OUT
,
Temperature and Faults
– Programmable Voltage, Current Limit, Digital
Soft-Start/Stop, Sequencing, Margining, OV/UV/OC
and Frequency Synchronization (250kHz to 1MHz)
n
±0.5% Output Voltage Accuracy over Temperature
n
Integrated 16-Bit ADC and 12-Bit DAC
n
Integrated High Side Current Sense Amplifier
n
Internal EEPROM and Fault Logging
n
Integrated N-Channel MOSFET Gate Drivers
Power Conversion
n
Wide V Range: 4.5V to 24V
IN
n
V
OUT
Range: 0.5V to 5.5V
n
Analog Current Mode Control Loop
n
Accurate PolyPhase
®
Current Sharing for
Up to 6 Phases
n
Auto Calibration of Inductor DCR
n
Available in a 32-Lead (5mm
×
5mm) QFN Package
applicaTions
n
n
n
High Current Distributed Power Systems
Telecom Systems
Intelligent Energy Efficient Power Regulation
Typical applicaTion
V
IN
6V TO 24V
5m
10µF
100
1µF
I
IN_SNS
V
IN_SNS
22µF
V
IN
LTC3883*
PMBus
INTERFACE
SDA
SCL
ALERT
RUN
GPIO
PGOOD
I
SENSE+
I
SENSE–
V
SENSE
TSNS
2200pF
I
TH
V
DD33
V
DD25
SGND
3883 TA01a
100
INTV
CC
TG
BOOST
SW
BG
D1
0.1µF
1µF
M1
10µF
100
90
0.56µH
M2
1.4k
0.22µF
V
OUT
1.8V
20A
80
EFFICIENCY (%)
70
60
50
40
30
20
10
Efficiency and Power Loss
vs Load Current
V
IN
= 12V
V
OUT
= 1.8V
f
SW
= 350kHz
8
7
6
POWER LOSS (W)
5
4
3
2
1
1
0.1
10
LOAD CURRENT (A)
0
100
3883 TA01b
10nF
4.99k
FAULT
MANAGEMENT
TO/FROM
OTHER LTC DEVICES
WRITE PROTECT
MMBT3906
C
OUT
530µF
0
0.01
1µF
1µF
*SOME DETAILS OMITTED
FOR CLARITY
SHARE_CLK
WP
3883f
1
LTC3883/LTC3883-1
Features ..................................................... 1
Applications ................................................ 1
Typical Application ........................................ 1
Description.................................................. 1
Table of Contents .......................................... 2
Absolute Maximum Ratings .............................. 4
Pin Configuration .......................................... 4
Order Information .......................................... 4
Electrical Characteristics ................................. 5
Typical Performance Characteristics ................... 9
Pin Functions .............................................. 12
Block Diagram............................................. 14
Operation................................................... 15
Overview ................................................................. 15
Main Control Loop .................................................. 15
EEPROM ................................................................. 16
Power Up and Initialization ..................................... 16
Soft-Start ................................................................ 17
Sequencing ............................................................. 17
Voltage-Based Sequencing ..................................... 18
Shutdown ............................................................... 18
Light Load Current Operation ................................. 19
Switching Frequency and Phase ............................. 19
Output Voltage Sensing .......................................... 20
Output Current Sensing .......................................... 20
Auto Calibration ..................................................... 20
Accurate DCR Temperature Compensation ............ 20
Input Current Sensing ............................................. 20
Load Sharing .......................................................... 21
External/Internal Temperature Sense ...................... 21
RCONFIG (Resistor Configuration) Pins ..................22
Fault Detection and Handling ..................................23
CRC Failure ........................................................ 24
Serial Interface ....................................................... 24
Communication Failure ...................................... 24
Device Addressing .................................................. 24
Table oF conTenTs
Responses to V
OUT
and I
OUT
Faults ........................25
Output Overvoltage Fault Response ...................25
Output Undervoltage Response ......................... 25
Peak Output Overcurrent Fault Response ........... 25
Responses to Timing Faults ....................................26
Responses to V
IN
OV Faults ....................................26
Responses to OT/UT Faults.....................................26
Overtemperature Fault Response—Internal ...... 26
Overtemperature and Undertemperature
Fault Response—Externals ...............................26
Responses To Input Overcurrent And Output
Undercurrent Faults ................................................ 27
Responses to External Faults ................................. 27
Fault Logging .......................................................... 27
Bus Timeout Failure ................................................ 27
Similarity Between PMBus, SMBus and I
2
C
2-Wire Interface ...................................................... 27
PMBus Serial Digital Interface ................................ 28
PMBus Command Summary ............................ 31
PMBus Commands ................................................. 31
*Data Format ..........................................................36
Applications Information ................................ 37
Current Limit Programming .................................... 37
I
SENSE+
and I
SENSE–
Pins......................................... 37
Low Value Resistor Current Sensing.......................38
Inductor DCR Current Sensing................................39
Slope Compensation and Inductor Peak Current ....40
Inductor Value Calculation ......................................40
Inductor Core Selection .......................................... 41
Power MOSFET and Schottky Diode (Optional)
Selection ................................................................. 41
Variable Delay Time, Soft-Start and Output Voltage
Ramping ................................................................. 42
Digital Servo Mode .................................................43
Soft Off (Sequenced Off) ........................................43
INTV
CC
Regulator....................................................44
3883f
2
LTC3883/LTC3883-1
Table oF conTenTs
Topside MOSFET Driver Supply (C
B
, D
B
) ................45
Undervoltage Lockout.............................................45
C
IN
and C
OUT
Selection ...........................................45
Fault Conditions ......................................................46
Open-Drain Pins ..................................................... 47
Phase-Locked Loop and Frequency
Synchronization ...................................................... 47
Minimum On-Time Considerations..........................48
Input Current Sense Amplifier.................................48
RCONFIG (External Resistor
Configuration Pins) ................................................. 49
Voltage Selection ................................................ 49
Frequency and Phase Selection Using
RCONFIG ............................................................ 51
Address Selection Using RCONFIG ..................... 51
Efficiency Considerations ....................................... 52
Checking Transient Response ................................. 52
PolyPhase Configuration ....................................53
PC Board Layout Checklist .....................................54
PC Board Layout Debugging ...................................56
Design Example ......................................................56
Connecting the USB to I
2
C/SMBus/PMBus
Controller to the LTC3883 In System ......................58
Inductor DCR Auto Calibration ............................... 59
Accurate DCR Temperature Compensation .............60
LTpowerPlay: An Interactive GUI for
Digital Power .......................................................... 61
PMBus Communication and Command Processing 61
PMBus Command Details ............................... 64
Addressing and Write Protect .................................64
General Configuration Registers .............................65
On/Off/Margin ........................................................66
PWM Configuration ................................................68
Voltage.................................................................... 70
Input Voltage and Limits..................................... 70
Output Voltage and Limits .................................. 71
Current.................................................................... 74
Output Current Calibration ................................. 74
Output Current .................................................... 76
Input Current Calibration ...................................77
Input Current ...................................................... 78
Temperature............................................................ 78
External Temperature Calibration........................ 78
External Temperature Limits............................... 79
Timing ....................................................................80
Timing—On Sequence/Ramp.............................80
Timing—Off Sequence/Ramp ............................ 81
Precondition for Restart ..................................... 81
Fault Response .......................................................82
Fault Responses All Faults ..................................82
Fault Responses Input Voltage ...........................82
Fault Responses Output Voltage .........................83
Fault Responses Output Current .........................85
Fault Responses IC Temperature ........................86
Fault Responses External Temperature............... 87
Fault Sharing...........................................................88
Fault Sharing Propagation ..................................88
Fault Sharing Response ......................................90
Scratchpad .............................................................90
Identification ........................................................... 91
Fault Warning and Status........................................92
Telemetry ................................................................98
NVM Memory Commands .................................... 101
Store/Restore ................................................... 101
Fault Logging .................................................... 102
Block Memory Write/Read................................ 105
Typical Applications .................................... 107
Package Description ................................... 111
Typical Application ..................................... 112
Related Parts ............................................ 112
3883f
3
LTC3883/LTC3883-1
absoluTe maximum raTings
(Note 1)
V
IN
, SW ...................................................... –0.3V to 28V
Topside Driver Voltage (BOOST) ................ –0.3V to 34V
Switch Transient Voltage (SW) ..................... –5V to 28V
EXTV
CC
, INTV
CC
, BG, (BOOST – SW) ......... –0.3V to 6V
V
SENSE+
, I
SENSE+
........................................... –0.3V to 6V
RUN, SDA, SCL,
ALERT
............................. –0.3V to 5.5V
FREQ_CFG, V
OUT_CFG
, V
TRIM_CFG
,
ASEL, V
DD25
............................................ –0.3V to 2.75V
(V
IN_SNS
– V
IN
), (V
IN
– I
IN_SNS
) ................ –0.3V to 0.3V
PGOOD,
GPIO,
SHARE_CLK, I
TH
,
V
DD33
, WP ................................................ –0.3V to 3.6V
INTV
CC
Peak Output Current ................................100mA
Operating Junction Temperature Range
(Notes 2, 15) .......................................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 125°C
pin conFiguraTion
LTC3883
V
SENSE–
TSNS
TOP VIEW
V
SENSE+
INTV
CC
PGND
V
IN
I
TH
BG
LTC3883-1
V
SENSE–
TSNS
TOP VIEW
V
SENSE+
EXTV
CC
PGND
24 BOOST
23 TG
22 SW
33
GND
21 V
DD33
20 SHARE_CLK
19 WP
18 V
DD25
17 V
TRIM_CFG
9 10 11 12 13 14 15 16
V
OUT_CFG
PGOOD
ASEL
GPIO
RUN
DNC
FREQ_CFG
DNC
V
IN
I
TH
BG
32 31 30 29 28 27 26 25
V
IN_SNS
1
I
IN_SNS
2
I
SENSE
+
32 31 30 29 28 27 26 25
24 BOOST
23 TG
22 SW
21 V
DD33
20 SHARE_CLK
19 WP
18 V
DD25
17 V
TRIM_CFG
V
IN_SNS
1
I
IN_SNS
2
I
SENSE
+
3
33
GND
3
I
SENSE–
4
SYNC 5
SCL 6
SDA 7
ALERT
8
I
SENSE–
4
SYNC 5
SCL 6
SDA 7
ALERT
8
9 10 11 12 13 14 15 16
V
OUT_CFG
PGOOD
ASEL
GPIO
RUN
DNC
FREQ_CFG
DNC
UH PACKAGE
32-LEAD (5mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 44°C/W,
θ
JC
= 7.3°C/W
EXPOSED PAD (PIN 33) IS GND, MUST BE SOLDERED TO PCB
UH PACKAGE
32-LEAD (5mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 44°C/W,
θ
JC
= 7.3°C/W
EXPOSED PAD (PIN 33) IS GND, MUST BE SOLDERED TO PCB
orDer inFormaTion
LEAD FREE FINISH
LTC3883EUH#PBF
LTC3883IUH#PBF
LTC3883EUH-1#PBF
LTC3883IUH-1#PBF
TAPE AND REEL
LTC3883EUH#TRPBF
LTC3883IUH#TRPBF
LTC3883EUH-1#TRPBF
LTC3883IUH-1#TRPBF
PART MARKING*
3883
3883
38831
38831
PACKAGE DESCRIPTION
32-Lead (5mm
×
5mm) Plastic QFN
32-Lead (5mm
×
5mm) Plastic QFN
32-Lead (5mm
×
5mm) Plastic QFN
32-Lead (5mm
×
5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 105°C
–40°C to 125°C
–40°C to 105°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 non-standard 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/
3883f
4
LTC3883/LTC3883-1
elecTrical characTerisTics
SYMBOL
PARAMETER
Input Voltage
V
IN
Input Voltage Range
I
Q
Input Voltage Supply Current
Normal Operation
V
UVLO
Undervoltage Lockout Threshold
when V
IN
> 4.2V
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= 12V, V
RUN
= 3.3V, f
SYNC
= 500kHz (externally
driven) unless otherwise specified.
CONDITIONS
(Note 12)
(Note 14)
V
RUN
= 3.3V, No Caps on TG and BG
V
RUN
= 0V
V
INTVCC
/V
EXTVCC
Falling
V
INTVCC
/V
EXTVCC
Rising
VOUT_COMMAND = 5.500V (Note 9)
l
MIN
4.5
TYP
MAX
24
UNITS
V
mA
mA
V
V
30
20
3.7
3.95
l
l
Control Loop
V
OUTR0
Full-Scale Voltage Range 0
Set Point Accuracy (0.6V to 5V)
Resolution
LSB Step Size
V
OUTR1
Full-Scale Voltage Range 1
Set Point Accuracy (0.6V to 2.5V)
Resolution
LSB Step Size
V
LINEREG
Line Regulation
V
LOADREG
Load Regulation
g
m
I
ISENSE
V
SENSERIN
V
IlLIMIT
Error Amplifier g
m
Input Current
V
SENSE
Input Resistance to Ground
Resolution
V
ILIMMAX
V
ILIMMIN
Gate Driver
TG
TG Transition Time:
t
r
Rise Time
Fall Time
t
f
BG
BG Transition Time:
t
r
Rise Time
Fall Time
t
f
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay Time
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay Time
t
ON(MIN)
Minimum On-Time
OV/UV Output Voltage Supervisor
N
Resolution
V
RANGE0
Voltage Range
V
RANGE1
Voltage Range
V
OUSTP0
Step Size
V
OUSTP1
Step Size
V
THACC0
Threshold Accuracy 2V < V
OUT
< 5V
V
THACC1
Threshold Accuracy 0.9V < V
OUT
< 2.5V
t
PROPOV1
OV Comparator to GPIO Low Time
t
PROPUV1
UV Comparator to GPIO Low Time
V
IN
Voltage Supervisor
N
Resolution
5.422
–0.5
2.711
–0.5
12
1.375
12
0.6875
0.01
–0.01
3
±1
47
3
75
50
37.5
25
5.576
0.5
2.788
0.5
±0.02
0.1
–0.1
±2
VOUT_COMMAND = 2.75V (Note 9)
l
l
6V < V
IN
< 24V
∆V
ITH
= 1.35V – 0.7V
∆V
ITH
= 1.35V – 2.0V
I
TH
=1.22V
V
ISENSE
= 5.5V
0V ≤ V
PIN
≤ 5.5V
Hi Range
Lo Range
Hi Range
Lo Range
(Note 4)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
(Note 4)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
(Note 4) C
LOAD
= 3300pF
(Note 4) C
LOAD
= 3300pF
l
l
l
l
l
l
68
44
82
56
V
%
Bits
mV
V
%
Bits
mV
%/V
%
%
mmho
µA
kΩ
bits
mV
mV
mV
mV
30
30
20
20
10
30
90
8
ns
ns
ns
ns
ns
ns
ns
bits
V
V
mV
mV
%
%
µs
µs
bits
3883f
Range Value = 0
Range Value = 1
Range Value = 0
Range Value = 1
Range Value = 0
Range Value = 1
V
OD
= 10% of Threshold
V
OD
= 10% of Threshold
1
0.4
22
11
l
l
5.5
2.7
±2
±2
35
35
8
5
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