LTC1698 Datasheet PDF - Linear
Part Number | LTC1698 | |
Description | Isolated Secondary Synchronous Rectifier Controller | |
Manufacturers | Linear | |
Logo | ||
There is a preview and LTC1698 download ( pdf file ) link at the bottom of this page. Total 24 Pages |
Preview 1 page No Preview Available ! LTC1698
Isolated Secondary
Synchronous Rectifier Controller
FEATURES
s High Efficiency Over Wide Load Current Range
s ±0.8% Output Voltage Accuracy
s Dual N-Channel MOSFET Synchronous Drivers
s Pulse Transformer Synchronization
s Optocoupler Feedback Driver
s Programmable Current Limit Protection
s ±5% Margin Output Voltage Adjustment
s Adjustable Overvoltage Fault Protection
s Power Good Flag
s Auxiliary 3.3V Logic Supply
s Available in 16-Lead SSOP and SO Packages
U
APPLICATIO S
s 48V Input Isolated DC/DC Converters
s Isolated Telecommunication Power Systems
s Distributed Power Step-Down Converters
s Industrial Control Systems
s Automotive and Heavy Equipment
DESCRIPTIO
The LTC®1698 is a precision secondary-side forward
converter controller that synchronously drives external
N-channel MOSFETs. It is designed for use with the
LT®3781 primary-side synchronous forward converter
controller to create a completely isolated power supply.
The LT3781 synchronizes the LTC1698 through a small
pulse transformer and the LTC1698 drives a feedback
optocoupler to close the feedback loop. Output accuracy
of ±0.8% and high efficiency over a wide range of load
currents are obtained.
The LTC1698 provides accurate secondary-side current
limit using an external current sense resistor. The input
voltage at the MARGIN pin provides ±5% output voltage
adjustment. A power good flag and overvoltage input are
provided to ensure proper power supply conditions. An
auxiliary 3.3V logic supply is included that supplies up to
10mA of output current.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
VIN
36V to 72V
Q1
L1
VDD BIAS +
+
COUT
R2
R1
VOUT
D1
T1
Q2 D2
RPRISEN
TG BG
CSG
SG
T2
Q4
Q3
RSECSEN
CSYNC
RSYNC
1 10
2 VDD PWRGD 8
CG VFB
16
FG LTC1698
12
ISNS
6
VCOMP
RC
CC
CFB
11
ISNSGND
13 RCILM
ICOMP
CCILM
15
SYNC
9
OVPIN
7
MARGIN
VMARGIN
R5
R4
LT3781
+ REF
– VFB
VC
RF
CF
RE
ISOLATION
BOUNDARY
RK 5
14 VAUX
OPTODRV
VAUX
3.3V
CK PGND GND O.1µF 10mA
34
1681 F01
PLEASE REFER TO FIGURE 12 IN THE TYPICAL APPLICATIONS
SECTION FOR THE COMPLETE 3.3V/15A APPLICATION SCHEMATIC
Figure 1. Simplified 2-Transistor Isolated Forward Converter
1698f
1
|
|
TYPICAL PERFOR A CE CHARACTERISTICS
LTC1698
VAUX vs Temperature
3.465
VDD = 8V
3.424 ILOAD = 0mA
3.383
3.341
3.300
3.259
3.218
3.176
3.135
–50 –25
0 25 50 75 100 125 150
TEMPERATURE (°C)
1698 G10
VAUX vs Line Voltage
3.465
VDD = 8V
3.424 ILOAD = 0mA
3.383
3.341
3.300
3.259
3.218
3.176
3.135
5 6 7 8 9 10 11 12 13 14
VDD (V)
1698 G11
VAUX vs Load Current
3.465
VDD = 8V
3.424 TA = 25°C
3.383
3.341
3.300
3.259
3.218
3.176
3.135
0 1 2 3 4 5 6 7 8 9 10
LOAD CURRENT (mA)
1698 G12
VAUX Short-Circuit Current
vs Temperature
0
VDD = 8V
–10
–20
–30
–40
–50
–50 –25
0 25 50 75 100 125 150
TEMPERATURE (°C)
1698 G13
Maximum OPTO Driver Output
Voltage vs Load Current
8
VDD = 10V
6
VDD = 8V
VDD = 7V
4
VDD = 6V
VDD = 5V
2
TA = 25°C
VCOMP = 0V
0
0 1234567
LOAD CURRENT (mA)
8
9 10
1698 G22
VAUX Short-Circuit Current
vs VDD
0
TA = 25°C
–10
–20
–30
–40
–50
5 6 7 8 9 10 11 12 13 14
VDD (V)
1698 G14
Opto Driver Load Regulation
3.030
3.024
3.018
VDD = 8V
TA = 25°C
1.0
0.8
0.6
3.012
0.4
3.006
0.2
3.000
0
2.994
–0.2
2.988
–0.4
2.982
–0.6
2.976
–0.8
2.970
–1.0
0 1 2 3 4 5 6 7 8 9 10
LOAD CURRENT (mA)
1698 G15
Maximum OPTO Driver Output
Voltage vs Temperature
8
VDD = 10V
6
VDD = 8V
VDD = 7V
4
VDD = 6V
VDD = 5V
2
Opto Driver Short-Circuit Current
vs Temperature
–10
VDD = 8V
–15 VOPTODRV = 1.233V
–20
–25
–30
–35
–40
VCOMP = 0V
IOPTODRV = –10mA
0
–50 –25 0 25
50
75 100 125 150
TEMPERATURE (°C)
1698 G23
–45
–50
–50 –25
0 25 50 75 100 125 150
TEMPERATURE (°C)
1698 G16
1698f
5
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Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for LTC1698 electronic component. |
Information | Total 24 Pages | |
Link URL | [ Copy URL to Clipboard ] | |
Download | [ LTC1698.PDF Datasheet ] |
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