FeaTures
n
LTC3886
60V Dual Output
Step-Down Controller with Digital
Power System Management
DescripTion
The
LTC
®
3886
is a dual PolyPhase DC/DC synchronous
step-down switching regulator controller with I
2
C-based
PMBus compliant serial interface.
This controller employs
a constant-frequency, current-mode architecture, with high
voltage input and output capability along with program-
mable loop compensation. The LTC3886 is supported by
the
LTpowerPlay™
software development tool with graphical
user interface (GUI).
The EXTV
CC
pin supports voltages up to 14V allowing for
optimized circuit efficiency and die temperature, and for
the controller output to supply the chip power. Switch-
ing frequency, output voltage, and device address can be
programmed both by digital interface as well as external
configuration resistors. Parameters can be set via the
digital interface or stored in EEPROM. Both outputs have
an independent power good indicator and
FAULT
function.
The LTC3886 can be configured for discontinuous (pulse-
skipping) mode or continuous inductor current mode.
L,
LT, LTC, LTM, µModule, PolyPhase, Linear Technology and the Linear logo 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
5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 5408150, 6580258, 6304066,
7420359, 8786268 Patent Pending. Licensed under U.S. Patent 7000125 and other related
patents worldwide.
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,
Frequency, and Control Loop Compensation
n
Output Error Less Than ±0.5% 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 60V
IN
n
V
OUT0
, V
OUT1
Range: 0.5V to 13.8V
n
Analog Current Mode Control
n
Accurate PolyPhase
®
Current Sharing for
Up to 6 Phases (100kHz to 750kHz)
n
Available in a 52-Lead (7mm
×
8mm) QFN Package
applicaTions
n
n
Telecom, Datacom, and Storage Systems
Industrial and Point of Load Applications
Typical applicaTion
5m
10µF
0.1µF
3.1µH
INTV
CC
V
IN
I
IN+
I
IN–
TG0
BOOST0
SW0
BG0
PMBus
INTERFACE
TG1
BOOST1
SW1
0.1µF
6.82µH
100
90
7.5k
EFFICIENCY (%)
FAULT MANAGEMENT
TO/FROM
OTHER LTC DEVICES
0.22µF 7.5k
V
OUT1
12V
15A
1µF
80
70
60
50
40
30
20
10
0
0.01
1
0.1
10
LOAD CURRENT (A)
1µF
10µF
2
V
IN
18V TO 48V
Efficiency and Power Loss
vs Load Current
V
IN
= 48V
V
OUT
= 12V
f
SW
= 150kHz
9
8
7
6
5
4
3
2
1
0
100
3883 TA01b
6.81k
1µF
BG1
LTC3886*
FAULT0
SDA
FAULT1
SCL
PGOOD0
ALERT
PGOOD1
RUN0
RUN1 SHARE_CLK
0.22µF
I
SENSE0+
I
SENSE1+
I
SENSE0–
I
SENSE1–
EXTV
CC
V
SENSE0+
V
SENSE1
V
SENSE0–
TSNS0
TSNS1
I
TH0
I
TH1
I
THR0
I
THR1
V
DD33
GND V
DD25
1µF
1µF
POWER LOSS (W)
6.81k
V
OUT0
5V
15A
530µF
+
10nF
4700pF
220pF
+
2200pF
220pF
*SOME DETAILS OMITTED FOR CLARITY
10nF
530µF
3886 TA01a
For more information
www.linear.com/LTC3886
1
3886f
LTC3886
Table oF conTenTs
3886
Responses to V
OUT
and I
OUT
Faults ........................ 27
Output Overvoltage Fault Response ................... 27
Output Undervoltage Response ......................... 27
Peak Output Overcurrent Fault Response ........... 27
Responses to Timing Faults .................................... 28
Responses to V
IN
OV Faults .................................... 28
Responses to OT/UT Faults..................................... 28
Internal Overtemperature Fault/Warn Response 28
External Overtemperature and Undertemperature
Fault Response .................................................. 28
Responses to Input Overcurrent and Output
Undercurrent Faults ................................................29
Responses to External Faults .................................29
Fault Logging ..........................................................29
Bus Timeout Protection ..........................................29
Similarity Between PMBus, SMBus and I
2
C
2-Wire Interface ......................................................30
PMBus Serial Digital Interface ................................30
PMBus Command Summary ............................ 35
PMBus Commands .................................................35
*Data Format ..........................................................40
Applications Information ................................ 41
Current Limit Programming .................................... 41
I
SENSE+
and I
SENSE–
Pins......................................... 41
Low Value Resistor Current Sensing ....................... 42
Inductor DCR Current Sensing................................43
Slope Compensation and Inductor Peak Current ....44
Inductor Value Calculation ......................................44
Inductor Core Selection ..........................................45
Power MOSFET and Optional Schottky Diode
Selection .................................................................45
C
IN
and C
OUT
Selection ...........................................46
Variable Delay Time, Soft-Start and Output Voltage
Ramping .................................................................46
Digital Servo Mode ................................................. 47
Soft Off (Sequenced Off) ........................................48
INTV
CC
Regulator....................................................48
Topside MOSFET Driver Supply (C
B
, D
B
) ................ 49
Fault Indications .....................................................50
Features ..................................................... 1
Applications ................................................ 1
Typical Application ........................................ 1
Description.................................................. 1
Table of Contents .......................................... 2
Absolute Maximum Ratings .............................. 4
Order Information .......................................... 4
Pin Configuration .......................................... 4
Electrical Characteristics ................................. 5
Typical Performance Characteristics .................. 10
Pin Functions .............................................. 13
Block Diagram............................................. 15
Operation................................................... 16
Overview ................................................................. 16
Main Control Loop .................................................. 16
EEPROM ................................................................. 17
Power-Up and Initialization ..................................... 17
Soft-Start ................................................................ 18
Time-Based Sequencing ......................................... 18
Event-Based Sequencing ........................................ 19
Shutdown ............................................................... 19
Light-Load Current Operation ................................. 19
PWM Loop Compensation ......................................20
Switching Frequency and Phase .............................20
Output Voltage Sensing ..........................................20
Output Current Sensing ..........................................20
Input Current Sensing ............................................. 21
PolyPhase Load Sharing ......................................... 21
External/Internal Temperature Sense ...................... 21
RCONFIG (Resistor Configuration) Pins ..................22
Fault Handling .........................................................23
Status Registers and
ALERT
Masking................. 24
Mapping Faults to
FAULT
Pins ............................ 24
Power Good Pins ................................................26
CRC Protection ..................................................26
Serial Interface .......................................................26
Communication Protection ................................26
Device Addressing ..................................................26
2
3886f
For more information
www.linear.com/LTC3886
LTC3886
Table oF conTenTs
Open-Drain Pins .....................................................50
Phase-Locked Loop and Frequency
Synchronization ...................................................... 51
Minimum On-Time Considerations.......................... 52
External Temperature Sense ................................... 52
Derating EEPROM Retention at Temperature ......53
Input Current Sense Amplifier.................................53
External Resistor Configuration Pins (RCONFIG) ....54
Voltage Selection ................................................54
Frequency Selection ..........................................55
Phase Selection ..................................................55
Address Selection Using RCONFIG .....................56
Efficiency Considerations .......................................56
Programmable Loop Compensation ....................... 57
Checking Transient Response ................................. 57
PolyPhase Configuration ........................................58
PC Board Layout Debugging ...................................60
Design Example ......................................................62
Additional Design Checks .......................................63
Connecting the USB to I
2
C/SMBus/PMBus
Adapter to the LTC3886 In System .........................63
PMBus Communication and Command
Processing ..............................................................65
PMBus Command Details ............................... 67
Addressing and Write Protect ................................. 67
General Configuration COMMANDS........................69
On/Off/Margin ........................................................ 70
ON_OFF_CONFIG .................................................... 71
PWM Configuration ................................................ 72
Voltage.................................................................... 76
Input Voltage and Limits..................................... 76
Output Voltage and Limits ..................................77
Output Current and Limits ......................................80
Input Current and Limits .................................... 82
Temperature............................................................83
External Temperature Calibration........................83
Timing ....................................................................84
Timing—On Sequence/Ramp.............................84
Timing—Off Sequence/Ramp ............................85
Precondition for Restart .....................................86
Fault Response .......................................................86
Fault Responses All Faults ..................................86
Fault Responses Input Voltage ........................... 87
Fault Responses Output Voltage ......................... 87
Fault Responses Output Current .........................90
Fault Responses IC Temperature ........................ 91
Fault Responses External Temperature...............92
Fault Sharing...........................................................93
Fault Sharing Propagation ..................................93
Fault Sharing Response ......................................95
Scratchpad .............................................................95
Identification ...........................................................96
Fault Warning and Status........................................ 97
Telemetry .............................................................. 103
EEPROM Memory Commands .............................. 106
Store/Restore ................................................... 106
Fault Logging .................................................... 107
Block Memory Write/Read.................................111
Typical Applications .................................... 112
Package Description ................................... 115
Typical Application ..................................... 116
Related Parts ............................................ 116
For more information
www.linear.com/LTC3886
3
3886f
LTC3886
absoluTe MaxiMuM raTings
Top Gate Transient Voltage (TG0, TG1) .......–0.3V to 71V
BOOST0, BOOST1 .......................................–0.3V to 71V
Switch Transient Voltage (SW0, SW1) .......... –5V to 65V
INTV
CC
, BG0, BG1, (BOOST0– SW0),
(BOOST1– SW1) .......................................... –0.3V to 6V
V
SENSE0+
, V
SENSE1+
, I
SENSE0+
, I
SENSE1+
,
I
SENSE0 –,
I
SENSE1–
, EXTV
CC
........................ –0.3V to 15V
V
SENSE0 –
................................................... –0.3V to 0.3V
RUN, SDA, SCL,
ALERT
............................. –0.3V to 5.5V
ASELn, V
OUTn_CFG
, FREQ_CFG,
PHAS_CFG, V
DD25
.................................. –0.3V to 2.75V
(V
IN
– I
INP
), (V
IN
– I
INM
) ............................ –0.3V to 0.3V
PGOOD0, PGOOD1,
FAULT,
SHARE_CLK,
I
TH0
, I
TH1
, I
THR0
, I
THR1
, V
DD33
, WP,
TSNS0, TSNS1, SYNC ............................... –0.3V to 3.6V
(EXTV
CC
– V
IN
) ......................................................13.2V
INTV
CC
Peak Output Current ................................100mA
Operating Junction Temperature Range
(Notes 2, 15, 16) .............................. –55°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.
pin conFiguraTion
BOOST0
EXTV
CC
TOP VIEW
INTV
CC
BG0
I
IN+
I
IN–
V
IN
BG1
40 BOOST1
39 SW1
38 TG1
I
SENSE0+
4
I
SENSE0–
5
TSNS0 6
V
SENSE0+
7
V
SENSE0–
8
I
SENSE1+
9
I
SENSE1–
10
I
THR0
11
I
TH0
12
SYNC 13
SCL 14
15 16 17 18 19 20 21 22 23 24 25 26
PHAS_CFG
FREQ_CFG
V
OUT0_CFG
V
OUT1_CFG
SDA
ALERT
FAULT0
FAULT1
RUN0
RUN1
ASEL0
ASEL1
53
GND
36 TSNS1
35 V
SENSE1+
34 PGOOD0
33 PGOOD1
32 I
THR1
31 I
TH1
30 V
DD33
29 SHARE_CLK
28 WP
27 V
DD25
(Note 1)
V
IN
, I
IN+
, I
IN –
.............................................. –0.3V to 65V
52
SW0 1
TG0 2
50
48 47 46
44 43 42
UKG PACKAGE
VARIATION: UKG52(46)
52-LEAD (7mm
×
8mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 31°C/W,
θ
JC
= 2°C/W
EXPOSED PAD (PIN 53) IS GND, MUST BE SOLDERED TO PCB
Note: Pins omitted to achieve high input voltage rating.
orDer inForMaTion
LEAD FREE FINISH
LTC3886EUKG#PBF
LTC3886IUKG#PBF
TAPE AND REEL
LTC3886EUKG#TRPBF
LTC3886IUKG#TRPBF
PART MARKING*
LTC3886UKG
LTC3886UKG
PACKAGE DESCRIPTION
52-Lead (7mm
×
8mm) Plastic QFN
52-Lead (7mm
×
8mm) 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/
4
3886f
For more information
www.linear.com/LTC3886
LTC3886
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
IN
= 16V, EXTV
CC
= 0V, V
RUN0
= 3.3V, V
RUN1
= 3.3V
f
SYNC
= 350kHz (externally driven), and all programmable parameters at factory default unless otherwise specified.
SYMBOL
PARAMETER
Input Voltage
Input Voltage Range
V
IN
Input Voltage Supply Current
I
Q
Normal Operation
V
UVLO
T
INIT
Undervoltage Lockout Threshold
When V
IN
> 4.2V
Initialization Time
CONDITIONS
(Note 12)
(Note 14)
V
RUN
= 3.3V, No Caps on TG and BG
V
RUN
= 0V
V
INTVCC
Falling
V
INTVCC
Rising
Delay from RESTORE_USER_ALL,
MFR_REST, or V
INTVCC
> V
UVLO
Until
TON_DELAY Can Begin
l
elecTrical characTerisTics
MIN
4.5
TYP
MAX
60
UNITS
V
mA
mA
V
V
ms
26
22
3.7
3.95
70
Control Loop
Range 0 Maximum V
OUT
V
OUTR0
Range 0 Set Point Accuracy
Range 0 Resolution
Range 0 LSB Step Size, FSR = 16.38
V
OUTR1
Range 1 Maximum V
OUT
Range 1 Set Point Accuracy
Range 1 Resolution
Range 1 LSB Step Size, FSR = 8.19V
V
LINEREG
Line Regulation
Load Regulation
V
LOADREG
g
m0,1
Resolution
Error Amplifier g
m(MAX)
Error Amplifier g
m(MIN)
Error Amplifier g
m
LSB Step Size
Resolution
Compensation Resistor R
ITHR(MAX)
Compensation Resistor R
ITHR(MIN)
Input Current
V
SENSE0
Input Current
V
SENSE1
Input Current
Resolution
V
ILIM(MAX)
V
ILIM(MIN)
Gate Driver
TG
t
r
t
f
BG
t
r
t
f
TG/BG t
1D
BG/TG t
2D
2.0V ≤ VOUT ≤ 13.8V
(Note 10)
1.0V ≤ V
OUT
≤ 6.6V
16V < V
IN
< 60V
∆V
ITH
= 1.35V – 0.7V
∆V
ITH
= 1.35V – 2.0V
I
TH
=1.35V
I
TH
=1.35V
I
TH
=1.35V
l
–0.5
14.0
12
4
7.0
12
2
0.01
–0.01
3
5.76
1.00
0.68
5
62
0
±1
200
250
3
75
50
37.5
25
0.5
l
–0.5
0.5
±0.02
0.1
–0.1
l
l
l
V
%
Bits
mV
V
%
Bits
mV
%/V
%
%
bits
mmho
mmho
mmho
bits
kΩ
kΩ
µA
µA
µA
bits
mV
mV
mV
mV
R
ITHR0,1
I
ISENSE
V
SENSE0(RIN)
V
SENSE1(RIN)
V
I(lLIMIT)
V
ISENSE
= 14V
V
PIN
= 14V
V
PIN
= 14V
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
±2
l
l
68
44
82
56
TG Transition Time:
Rise Time
Fall Time
BG Transition Time:
Rise Time
Fall Time
Top Gate Off to Bottom Gate On Delay Time
Bottom Gate Off to Top Gate On Delay Time
30
30
20
20
10
30
ns
ns
ns
ns
ns
ns
For more information
www.linear.com/LTC3886
5
3886f
