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LTC3731HUH#TRPBF

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LTC3731H
1
3731Hfb
Typical applicaTion
FeaTures DescripTion
3-Phase, 600kHz,
Synchronous Buck Switching
Regulator Controller
The LTC
®
3731H is a PolyPhase
®
synchronous step-down
switching regulator controller that drives all N-channel
external power MOSFET stages in a phase-lockable fixed
frequency architecture. The LTC3731H is rated for operation
up to 140°C junction temperature. The 3-phase controller
drives its output stages with 120° phase separation at
frequencies up to 680kHz per phase to minimize the RMS
current losses in both the input and output filter capacitors.
The
3
-phase technique effectively triples the fundamental
frequency, improving transient response while operating
each controller at an optimal frequency for efficiency and
ease of thermal design. Light load efficiency is optimized
by using a choice of output Stage Shedding or Burst Mode
operation.
The precision reference supports output voltages from
0.6V to 6V. Current foldback provides protection for the
external MOSFETs under short-circuit or overload condi-
tions. Please refer to the LTC3731 data sheet for 0°C to
70°C and –40°C to 85°C rated versions.
L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, OPTI-LOOP and PolyPhase
are registered trademarks and Stage Shedding is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents
including 5481178, 5929620, 6177787, 6144194, 6100678, 5408150, 6580258, 6462525,
6304066, 5705919.
Figure 1. High Current Triple Phase Step-Down Converter
applicaTions
n
3-Phase Current Mode Controller with Onboard
MOSFET Drivers
n
±5% Output Current Matching Optimizes Thermal
Performance and Size of Inductors and MOSFETs
n
±2% V
REF
Accuracy Over Temperature Up to 140°C
n
Reduced Power Supply Induced Noise
n
±10% Power Good Output Indicator
n
225kHz to 680kHz Per Phase, PLL, Fixed Frequency
n
PWM, Stage Shedding™ or Burst Mode
®
Operation
n
OPTI-LOOP
®
Compensation Minimizes C
OUT
n
Adjustable Soft-Start Current Ramping
n
Short-Circuit Shutdown Timer with Defeat Option
n
Overvoltage Soft Latch
n
Adjustable Undervoltage Lockout Threshold
n
Selectable Phase Output for Up to 12-Phase
Operation
n
Available in 36-Pin Narrow (0.209") SSOP and
5mm × 5mm QFN Packages
n
Automotive and Industrial Power Supplies
n
High Output Current DC/DC Power Supplies
V
IN
0.003Ω
0.8µH
22µF
35V
0.003Ω
0.8µH
V
IN
0.003Ω
C
OUT
470µF
4V
V
OUT
1.35V
55A
V
IN
5V TO 28V
0.8µH
V
IN
3731H F01
TG1V
CC
0.1µF
SW3 SW2 SW1
SW1
BG1
SENSE1
+
SENSE1
–
BOOST1
BOOST2
BOOST3
TG2
SW2
BG2
PGOOD
PLLIN
PLLFLTR
I
TH
0.01µF
680pF
5k
OPTIONAL SYNC IN
POWER GOOD INDICATOR
RUN/SS
SGND
EAIN
PGND
UVADJ
SENSE2
+
SENSE2
–
TG3
SW3
BG3
SENSE3
+
SENSE3
–
+
10µF
V
CC
4.5V TO 7V
+
LTC3731H
36k
12k
7.5k
100pF
6.04k
Efficiency vs I
OUT
EFFICIENCY (%)
0.1
LOAD CURRENT (A)
100
90
80
70
60
50
40
30
20
10
0
1 10 100
3731H F01b
V
IN
= 8V
V
OUT
= 1.5V
V
FCB
= OPEN
V
FCB
= 5V
V
FCB
= 0V
LTC3731H
2
3731Hfb
absoluTe MaxiMuM raTings
Topside Driver Voltages (BOOST
N
) ............ 38V to –0.3V
Switch Voltage (SW
N
) ................................... 32V to –5V
Boosted Driver Voltage (BOOST
N
– SW
N
) .... 7V to –0.3V
Peak Output Current <1ms (TG
N
, BG
N
) .......................5A
Supply Voltages (V
CC
, V
DR
), PGOOD
Pin Voltage ................................................... 7V to –0.3V
RUN/SS, PLLFLTR, PLLIN, UVADJ,
FCB Voltages ..............................................V
CC
to –0.3V
(Note 1)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
TOP VIEW
G PACKAGE
36-LEAD PLASTIC SSOP
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
V
CC
PLLIN
PLLFLTR
FCB
NC
NC
NC
EAIN
SGND
SENSE1
+
SENSE1
–
SENSE2
+
SENSE2
–
SENSE3
–
SENSE3
+
RUN/SS
I
TH
UVADJ
CLKOUT
PGOOD
BOOST1
TG1
SW1
BOOST2
TG2
SW2
V
DR
BG1
PGND
BG2
BG3
SW3
TG3
BOOST3
PHASMD
SGND
T
JMAX
= 140°C, θ
JA
= 70°C/W, θ
JC
= 25°C/W
PINS 5 AND 6 CAN BE GROUNDED OR NC
PIN 7 MUST BE LEFT AS NC
32
33
SGND
31 30 29 28 27 26 25
9 10 11 12
TOP VIEW
UH PACKAGE
32-LEAD (5mm s 5mm) PLASTIC QFN
13 14 15 16
17
18
19
20
21
22
23
24
8
7
6
5
4
3
2
1NC
NC
EAIN
SENSE1
+
SENSE1
–
SENSE2
+
SENSE2
–
SENSE3
–
BOOST2
TG2
SW2
V
CC
BG1
PGND
BG2
BG3
NC
FCB
PLLFLTR
PLLIN
CLKOUT
BOOST1
TG1
SW1
SENSE3
+
RUN/SS
I
TH
UVADJ
PHASMD/PG
BOOST3
TG3
SW3
T
JMAX
= 125°C, θ
JA
= 34°C/W, θ
JC
= 3°C/W
EXPOSED PAD (PIN 33) IS SGND, MUST BE SOLDERED TO PCB
PINS 1, 2 AND 32 MUST BE LEFT AS NC
pin conFiguraTion
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3731HG#PBF LTC3731HG#TRPBF LTC3731HG 36-Lead Plastic SSOP –40°C to 140°C
LTC3731HUH#PBF LTC3731HUH#TRPBF 3731
32-Lead (5mm × 5mm) Plastic QFN
–40°C to 140°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
SENSE
+
, SENSE
–
Voltages ........................ 5.5V to –0.3V
I
TH
Voltage ............................................... 2.4V to –0.3V
Operating Junction
Temperature Range (Note 2) .................. –40°C to 140°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature G Package (Soldering, 10sec) ..300°C
LTC3731H
3
3731Hfb
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= V
RUN/SS
= 5V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loop
V
REGULATED
Regulated Voltage at EAIN V
ITH
= 1.2V (Note 3)
l
0.594
0.590
0.600
0.600
0.606
0.614
V
V
V
SENSEMAX
Maximum Current Sense Threshold V
EAIN
= 0.5V, V
ITH
Open,
V
SENSE1
–
, V
SENSE2
–
, V
SENSE3
–
= 0.6V, 1.8V
l
65
60
75
75
85
90
mV
mV
I
MATCH
Maximum Current Threshold Match Worst-Case Error at V
SENSEMAX
–5 5 %
V
LOADREG
Output Voltage Load Regulation (Note 3)
Measured in Servo Loop, ∆I
TH
Voltage = 1.2V to 0.7V
Measured in Servo Loop, ∆I
TH
Voltage = 1.2V to 2V
l
l
0.1
–0.1
0.7
–0.7
%
%
V
REFLNREG
Output Voltage Line Regulation V
CC
= 4.5V to 7V 0.03 %/V
g
m
Transconductance Amplifier g
m
I
TH
= 1.2V, Sink/Source 25µA (Note 3)
l
3 5 7 mmho
g
mOL
Transconductance Amplifier GBW I
TH
= 1.2V (g
m
• Z
L
, Z
L
= Series 1k – 100kΩ – 1nF) 3 MHz
V
FCB
Forced Continuous Threshold
l
0.54 0.60 0.66 V
I
FCB
FCB Bias Current V
FCB
= 0.65V 0.2 0.7 µA
V
BINHIBIT
Burst Inhibit Threshold Measured at FCB Pin V
CC
– 1.5 V
CC
– 0.7 V
CC
– 0.3 V
UVR Undervoltage RUN/SS Reset V
CC
Lowered Until the RUN/SS Pin is Pulled Low 3.3 3.8 4.5 V
UVADJ Undervoltage Lockout Threshold 1.13 1.18 1.23 V
I
UVADJ
Undervoltage Bias Current At UVADJ Threshold 0.2 50 nA
I
Q
Input DC Supply Current
Normal Mode
Shutdown
(Note 4)
V
CC
= 5V
V
RUN/SS
= 0V
2.3
50
3.5
100
mA
µA
I
RUN/SS
Soft-Start Charge Current V
RUN/SS
= 1.9V –0.8 –1.5 –2.5 µA
V
RUN/SS
RUN/SS Pin ON Threshold V
RUN/SS
, Ramping Positive 1 1.5 1.9 V
V
RUN/SSARM
RUN/SS Pin Arming Threshold V
RUN/SS
, Ramping Positive Until Short-Circuit
Latch-Off is Armed
3.8 4.5 V
V
RUN/SSLO
RUN/SS Pin Latch-Off Threshold V
RUN/SS
, Ramping Negative 3.2 V
I
SCL
RUN/SS Discharge Current Soft-Short Condition V
EAIN
= 0.375V, V
RUN/SS
= 4.5V –5 –1.5 µA
I
SDLHO
Shutdown Latch Disable Current V
EAIN
= 0.375V, V
RUN/SS
= 4.5V 1.5 5 µA
I
SENSE
SENSE Pins Source Current SENSE1
+
, SENSE1
–
, SENSE2
+
, SENSE2
–
, SENSE3
+
,
SENSE3
–
All Equal 1.2V; Current at Each Pin
13 20 µA
DF
MAX
Maximum Duty Factor In Dropout, V
SENSEMAX
≤ 30mV 95 98.5 %
TG t
R
, t
F
Top Gate Rise Time
Top Gate Fall Time
C
LOAD
= 3300pF
C
LOAD
= 3300pF
30
40
90
90
ns
ns
BG t
R
, t
F
Bottom Gate Rise Time
Bottom Gate Fall Time
C
LOAD
= 3300pF
C
LOAD
= 3300pF
30
20
90
90
ns
ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
All Controllers, C
LOAD
= 3300pF Each Driver 50 ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
All Controllers, C
LOAD
= 3300pF Each Driver 60 ns
t
ON(MIN)
Minimum On-Time Tested with a Square Wave (Note 5) 110 ns
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LTC3731HUH#TRPBF

Mfr. #:
Buy LTC3731HUH#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 3-Phase, 600kHz, Sync Buck Sw Reg Cntr
Lifecycle:
New from this manufacturer.
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