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LTC3729EUH#TRPBF

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LTC3729
1
3729fb
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
550kHz, PolyPhase,
High Efficiency, Synchronous
Step-Down Switching Regulator
The LTC
®
3729 is a multiple phase, synchronous
step‑down current mode switching regulator controller
that drives N‑channel external power MOSFET stages in a
phase‑lockable fixed frequency architecture. The PolyPhase
controller drives its two output stages out of phase at
frequencies up to 550kHz to minimize the RMS ripple
currents in both input and output capacitors. The output
clock signal allows expansion for up to 12 evenly phased
controllers for systems requiring 15A to 200A of output
current. The multiple phase technique effectively multiplies
the fundamental frequency by the number of channels
used, improving transient response while operating each
channel at an optimum frequency for efficiency. Thermal
design is also simplified.
An internal differential amplifier provides true remote sens‑
ing of the regulated supply’s positive and negative output
terminals as required for high current applications.
A RUN/SS pin provides both soft‑start and optional timed,
short‑circuit shutdown. Current foldback limits MOSFET
dissipation during short‑circuit conditions when the
overcurrent latchoff is disabled. OPTI‑LOOP compensation
allows the transient response to be optimized over a wide
range of output capacitance and ESR values. The LTC3729
includes a power good output pin that indicates when the
output is within ±7.5% of the designed set point.
Figure 1. High Current Dual Phase Step-Down Converter
n
Wide V
IN
Range: 4V to 36V Operation
n
Reduces Required Input Capacitance and Power
Supply Induced Noise
n
±1% Output Voltage Accuracy
n
Phase-Lockable Fixed Frequency: 250kHz to 550kHz
n
True Remote Sensing Differential Amplifier
n
PolyPhase
®
Extends from Two to Twelve Phases
n
Reduces the Size and Value of Inductors
n
Current Mode Control Ensures Current Sharing
n
1.1MHz Effective Switching Frequency (2‑Phase)
n
OPTI‑LOOP
®
Compensation Reduces C
OUT
n
Power Good Output Voltage Indicator
n
Very Low Dropout Operation: 99% Duty Cycle
n
Adjustable Soft‑Start Current Ramping
n
Internal Current Foldback Plus Shutdown Timer
n
Overvoltage Soft‑Latch Eliminates Nuisance Trips
n
Available in 5mm × 5mm QFN
and 28‑Lead SSOP Packages
n
Desktop Computers/Servers
n
Large Memory Arrays
n
DC Power Distribution Systems
3729 TA01
TG1
BOOST1
SW1
BG1
PGND
SENSE1
+
SENSE1
–
TG2
BOOST2
SW2
BG2
INTV
CC
SENSE2
+
SENSE2
–
V
IN
RUN/SS
EAIN
I
TH
V
DIFFOUT
V
OS
–
V
OS
+
LTC3729
SGND
0.1µF
PGOOD
0.1µF
16k
1000pF
S
S
S
S
S
S
S
S
10Ω
3.3k
16k
+
10µF
35V
CERAMIC
×4
+
C
OUT
1000µF ×2
4V
L1, L2: CEPH149-IROMCC
OUT
: T510E108K004AS
D1, D2: UP5840
M1, M3: IRF7811W
M2, M4: IRF7822
V
OUT
1.6V/40A
L1
0.8µH
0.002Ω
V
IN
5V TO 28V
L2
0.8µH
D2
D1
M1
M2
×2
M3
M4
×2
0.47µF
S
0.47µF
10µF
0.002Ω
L, LT, LTC, LTM, PolyPhase, OPTI‑LOOP, Linear Technology and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
LTC3729
2
3729fb
ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage (V
IN
) ......................... 36V to –0.3V
Topside Driver Voltages (BOOST1,2)
......... 42V to –0.3V
Switch Voltage (SW1, 2)
.............................. 36V to –5 V
SENSE1
+
, SENSE2
+
, SENSE1
–
,
SENSE2
–
Voltages .........................(1.1)INTV
CC
to –0.3V
EAIN, V
OS
+
, V
OS
–
, EXTV
CC
, INTV
CC
,
RUN/SS, PGOOD Voltages
.......................... 7V to –0.3V
Boosted Driver Voltage (BOOST‑SW) ........... 7V to –0.3V
PLLFLTR, PLLIN, CLKOUT, PHASMD,
V
DIFFOUT
Voltages ..............INTV
CC
to –0.3V for V
IN
≥ 7V
(Note 1)
V
DIFFOUT
Voltages .............V
IN
– 2V to –0.3V for V
IN
< 7V
I
TH
Voltage ............................................... 2.7V to –0.3V
Peak Output Current <1µs(TGL1,2, BG1,2)
.................5A
INTV
CC
RMS Output Current ................................. 50mA
Operating Ambient Temperature
Range (Note 6)
......................................... –40°C to 85°C
Junction Temperature (Note 2)
............................. 125°C
Storage Temperature Range
................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
(G Package Only) .............................................. 300°C
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TOP VIEW
G PACKAGE
28-LEAD PLASTIC SSOP
28
27
26
25
24
23
22
21
20
19
18
17
16
15
RUN/SS
SENSE1
+
SENSE1
–
EAIN
PLLFLTR
PLLIN
PHASMD
I
TH
SGND
V
DIFFOUT
V
OS
–
V
OS
+
SENSE2
–
SENSE2
+
CLKOUT
TG1
SW1
BOOST1
V
IN
BG1
EXTV
CC
INTV
CC
PGND
BG2
BOOST2
SW2
TG2
PGOOD
T
JMAX
= 125°C, θ
JA
= 95°C/W
32 31 30 29 28 27 26 25
9 10 11 12 13
TOP VIEW
UH PACKAGE
32-LEAD 5mm × 5mm PLASTIC QFN
14 15 16
17
18
19
20
21
22
23
24
8
7
6
5
4
3
2
1EAIN
PLLFLTR
PLLIN
PHASMD
I
TH
SGND
V
DIFFOUT
V
OS
–
BOOST1
V
IN
BG1
EXTV
CC
INTV
CC
PGND
BG2
BOOST2
NC
SENSE1
–
SENSE1
+
NC
RUN/SS
CLKOUT
TG1
SW1
V
OS
+
NC
SENSE2
–
SENSE2
+
PGOOD
TG2
SW2
NC
θ
JA
= 34°C/W
EXPOSED PAD IS GND, MUST BE SOLDERED TO PCB
PIN CONFIGURATION
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3729EG#PBF LTC3729EG#TRPBF LTC3729
28‑Lead Plastic SSOP –40°C to 85°C
LTC3729EUH#PBF LTC3729EUH#TRPBF 3729
32‑Lead (5mm × 5mm)Plastic QFN
–40°C to 85°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/
LTC3729
3
3729fb
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loop
V
EAIN
Regulated Feedback Voltage (Note 3); I
TH
Voltage = 1.2V
l
0.792 0.800 0.808 V
V
SENSEMAX
Maximum Current Sense Threshold V
SENSE
–
= 5V
V
SENSE1, 2
= 5V
l
62
65
75
75
88
85
mV
mV
I
INEAIN
Feedback Current (Note 3) –5 –50 nA
V
LOADREG
Output Voltage Load Regulation (Note 3)
Measured in Servo Loop; I
TH
Voltage = 0.7V
Measured in Servo Loop; I
TH
Voltage = 2V
l
l
0.1
–0.1
0.5
–0.5
%
%
V
REFLNREG
Reference Voltage Line Regulation V
IN
= 3.6V to 30V (Note 3) 0.002 0.02 %/V
V
OVL
Output Overvoltage Threshold Measured at V
EAIN
l
0.84 0.86 0.88 V
UVLO Undervoltage Lockout V
IN
Ramping Down 3 3.5 4 V
g
m
Transconductance Amplifier g
m
I
TH
= 1.2V; Sink/Source 5µA; (Note 3) 3 mmho
g
mOL
Transconductance Amplifier Gain I
TH
= 1.2V; (g
m
xZ
L
; No Ext Load); (Note 3) 1.5 V/mV
I
Q
Input DC Supply Current
Normal Mode
Shutdown
(Note 4)
EXTV
CC
Tied to V
OUT
; V
OUT
= 5V
V
RUN/SS
= 0V
580
20
40
µA
µA
I
RUN/SS
Soft‑Start Charge Current V
RUN/SS
= 1.9V –0.5 –1.2 µA
V
RUN/SS
RUN/SS Pin ON Threshold V
RUN/SS
Rising 1.0 1.5 1.9 V
V
RUN/SSLO
RUN/SS Pin Latchoff Arming V
RUN/SS
Rising from 3V 3.8 4.5 V
I
SCL
RUN/SS Discharge Current Soft Short Condition V
EAIN
= 0.5V; V
RUN/SS
= 4.5V 0.5 2 4 µA
I
SDLDO
Shutdown Latch Disable Current V
EAIN
= 0.5V 1.6 5 µA
I
SENSE
Total Sense Pins Source Current Each Channel; V
SENSE1
–
, 2
–
= V
SENSE1
+
, 2
+
= 0V –85 –60 µA
DF
MAX
Maximum Duty Factor In Dropout 98 99.5 %
TG1, 2 t
r
TG1, 2 t
f
Top Gate Transition Time:
Rise Time
Fall Time
C
LOAD
= 3300pF
C
LOAD
= 3300pF
30
40
90
90
ns
ns
BG1, 2 t
r
BG1, 2 t
f
Bottom Gate Transition Time:
Rise Time
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
C
LOAD
= 3300pF Each Driver
90
ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch‑On Delay Time
C
LOAD
= 3300pF Each Driver
90
ns
t
ON(MIN)
Minimum On‑Time Tested with a Square Wave (Note 5) 100 ns
Internal V
CC
Regulator
V
INTVCC
Internal V
CC
Voltage 6V < V
IN
< 30V; V
EXTVCC
= 4V 4.8 5.0 5.2 V
V
LDO
INT INTV
CC
Load Regulation I
CC
= 0 to 20mA; V
EXTVCC
= 4V 0.2 1.0 %
V
LDO
EXT EXTV
CC
Voltage Drop I
CC
= 20mA; V
EXTVCC
= 5V 80 160 mV
V
EXTVCC
EXTV
CC
Switchover Voltage I
CC
= 20mA, EXTV
CC
Ramping Positive
l
4.5 4.7 V
V
LDOHYS
EXTV
CC
Switchover Hysteresis I
CC
= 20mA, EXTV
CC
Ramping Negative 0.2 V
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency V
PLLFLTR
= 1.2V 360 400 440 kHz
f
LOW
Lowest Frequency V
PLLFLTR
= 0V 230 260 290 kHz
f
HIGH
Highest Frequency V
PLLFLTR
≥ 2.4V 480 550 590 kHz
R
PLLIN
PLLIN Input Resistance 50 kΩ
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
RUN/SS
= 5V unless otherwise noted.
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LTC3729EUH#TRPBF

Mfr. #:
Buy LTC3729EUH#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators PolyPhase Controller QFN Package
Lifecycle:
New from this manufacturer.
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