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LTC3706EGN#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P22
LTC3706
1
3706fd
TYPICAL APPLICATION
DESCRIPTION
Secondary-Side Synchronous
Forward Controller with
PolyPhase Capability
The LTC
®
3706 is a PolyPhase capable secondary-side
controller for synchronous forward converters. When used
in conjunction with the LTC3705 gate driver and primary-
side controller, the part creates a complete isolated power
supply that combines the power of PolyPhase operation
with the speed of secondary-side control.
The LTC3706 has been designed to simplify the design
of highly efficient, secondary-side forward converters.
Working in concert with the LTC3705, the LTC3706 forms
a robust, self-starting converter that eliminates the need
for the separate bias regulator that is commonly used in
secondary-side control applications. In addition, a pro-
prietary scheme is used to multiplex gate drive signals
and DC bias power across the isolation barrier through a
single, tiny pulse transformer.
The LTC3706 provides remote sensing, accurate power
good and overvoltage monitoring circuits to support preci-
sion, high current applications. A linear regulator controller
with thermal protection is also provided to simplify the
generation of secondary-side bias voltage.
The LTC3706 is available in a 24-lead SSOP package.
36V-72V to 3.3V/20A Isolated Forward Converter
FEATURES
APPLICATIONS
n
Isolated 48V Telecommunication Systems
n
Internet Servers and Routers
n
Distributed Power Step-Down Converters
n
Automotive and Heavy Equipment
n
Secondary-Side Control for Fast Transient Response
n
Self-Starting Architecture Eliminates Need for
Separate Bias Regulator
n
Proprietary Gate Drive Encoding Scheme Reduces
System Complexity
n
PolyPhase
®
Operation Reduces C
IN
Requirements
n
Current Mode Control Ensures Current Sharing
n
PLL Fixed Frequency: 100kHz to 500kHz
n
±1% Output Voltage Accuracy
n
True Remote Sense Differential Amplifier
n
Power Good Output Voltage Monitor
n
High Voltage Linear Regulator Controller
n
Wide Supply Range: 5V to 30V
n
Available in a Narrow 24-Lead SSOP Package
NDRV
GND PGND VSLMT
UVLO
BOOST
LTC3705
BAS21
FQT7N10
0.22µF
10µF
25V
CMPSH1-4
1.2Ω
L1
1.2µH
TG TS BG IS
T2
1µF
162k
L1: COILCRAFT SER2010-122
T1: PULSE PA0807
T2: PULSE PA0297
33nF
30mΩ
1W
2mΩ
2W
Si7336ADP
Si7336ADP
×2
T1
••
MURS120
Si7852DP
Si7852DP
MURS120
V
CC
33nF
15k
1%
365k
1%
100k
2.2µF
25V
SS/FLT
FB/IN
+
FS/IN
–
V
IN
–
V
IN
+
330µF
6.3V
×3
2.2µF
16V
680pF
CZT3019
22.6k
1%
20k
102k
1%
V
OUT
–
3706 TA01
V
OUT
+
••
1µF
100V
×3
FG SW SG V
IN
NDRV V
CC
GND PGND PHASE SLP MODE REGSD
PT
+
I
S
+
I
S
–
PT
–
RUN/SS
LTC3706
ITH
FB
FS/SYNC
L, LT, LTC, LTM, PolyPhase, Burst Mode, Linear Technology and the Linear logo are registered
trademarks and No R
SENSE
and ThinSOT are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents
including 6144194, other patents pending.
LTC3706
2
3706fd
PIN CONFIGURATIONABSOLUTE MAXIMUM RATINGS
V
CC
........................................................... –0.3V to 10V
V
IN
........................................................... –0.3V to 33V
SW
............................................................... –5V to 50V
NDRV
......................................................... –0.3V to 13V
ITH, RUN/SS, V
SOUT
, V
S
+
, V
S
–
, REGSD ....... –0.3V to 7V
All Other Pins
............................................ –0.3V to 10V
Operating Temperature Range (Note 2)
LTC3706EGN .......................................–40°C to 85°C
LTC3706IGN ........................................–40°C to 85°C
Junction Temperature (Note 3)
............................ 125°C
Storage Temperature Range
.................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
...................300°C
(Note 1)
1
2
3
4
5
6
7
8
9
10
11
12
TOP VIEW
GN PACKAGE
24-LEAD PLASTIC SSOP
24
23
22
21
20
19
18
17
16
15
14
13
SG
FG
PGOOD
MODE
PHASE
FB
ITH
RUN/SS
V
SOUT
V
S
+
V
S
–
GND
V
CC
PGND
PT
+
PT
–
SW
V
IN
NDRV
REGSD
I
S
+
I
S
–
SLP
FS/SYNC
T
JMAX
= 125°C, θ
JA
= 130°C/W
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3706EGN#PBF LTC3706EGN#TRPBF LTC3706EGN 24-Lead Plastic SSOP –40°C to 85°C
LTC3706IGN#PBF LTC3706IGN#TRPBF LTC3706IGN 24-Lead Plastic SSOP –40°C to 85°C
LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3706EGN LTC3706EGN#TR LTC3706EGN 24-Lead Plastic SSOP –40°C to 85°C
LTC3706IGN LTC3706IGN#TR LTC3706IGN 24-Lead Plastic SSOP –40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
LTC3706
3
3706fd
ELECTRICAL CHARACTERISTICS
The l indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 7V, V
IN
= 15V, GND = PGND = 0V, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loop
V
FB
Regulated Feedback Voltage (Note 4) ITH = 1.2V
l
0.594 0.600 0.606 V
I
FB
Feedback Input Current (Note 4) 2 100 nA
∆V
FB(LINREG)
Feedback Voltage Line Regulation V
IN
= 6V to 30V, ITH = 1.2V 0.001 %/V
∆V
FB(LOADREG)
Feedback Voltage Load Regulation Measured in Servo Loop,
ITH = 0.5V to 2V
l
–0.01 –0.1 %
V
ISMAX
Maximum Current Sense Threshold R
SENSE
Mode, 0V < V
IS
–
< 5V
V
IS
–
= V
CC
, 0V < V
IS
+
< 2V (CT Mode)
68
1.15
78
1.28
88
1.4
mV
V
V
ISOC
Over-Current Shutdown Threshold R
SENSE
Mode, 0V < V
IS
–
< 5V
V
IS
–
= V
CC
, 0V < V
IS
+
< 2V (CT Mode)
87
1.45
100
1.65
113
1.85
mV
V
g
m
Transconductance Amplifier g
m
2.40 2.75 3.10 mS
I
RUN/SS(C)
Soft-Start Charge Current V
RUN/SS
= 2V –4 –5 –6 µA
I
RUN/SS(D)
Soft-Start Discharge Current 3 µA
V
RUN/SS
RUN/SS Pin On Threshold V
RUN/SS
Rising
l
0.4 0.45 0.5 V
t
ON,MIN
Minimum On-Time 200 ns
FG, SG R
UP
FG, SG Driver Pull-Up On Resistance FG, SG Low 1.5 2.7 Ω
FG, SG R
DOWN
FG, SG Driver Pull-Down On Resistance FG, SG High 1.5 2.7 Ω
PT
+
, PT
–
R
UP
PT
+
, PT
–
Driver Pull-Up Resistance PT
+
, PT
–
Low 1.5 2.7 Ω
PT
+
, PT
–
R
DOWN
PT
+
, PT
–
Driver Pull-Down Resistance PT
+
, PT
–
High 1.5 2.7 Ω
∆V
FB(OV)
Output Overvoltage Threshold V
FB
Rising 15 17 19 %
V
CC
Supply
V
CCOP
Operating Voltage Range 5 10 V
V
CCREG
Regulated Output Voltage 6.6 7.0 7.4 V
I
CC
Supply Current
Operating
Shutdown
f
OSC
= 200kHz (Note 5)
V
RUN/SS
= GND
4.2
240
mA
µA
V
UVLO
UV Lockout V
CC
Rising
l
4.52 4.60 4.70 V
V
HYS
UV Hysteresis 0.4 V
V
IN
Supply
V
INOP
Operating Voltage Range 5 30 V
I
IN
Supply Current
Normal Mode
Shutdown
f
OSC
= 200kHz
V
RUN/SS
= GND
900
460
µA
µA
V
INUVLO
UV Lockout V
IN
Rising
l
3.90 4.30 4.51 V
V
INHYS
0.2 V
V
REGSD
REGSD Shutdown Threshold V
REGSD
Rising 4 V
g
m,REGSD
REGSD Transconductance 5 µS
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P22

LTC3706EGN#PBF

Mfr. #:
Buy LTC3706EGN#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Secondary-Side Sync For Cntr w/ Polyphas
Lifecycle:
New from this manufacturer.
Delivery:
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