LTC1698| Datasheet

Datasheet preview, take a look at Datasheets before downloading (Data Sheet is available on manufacturer site)

LTC1698 Isolated Secondary Synchronous Rectifier Controller

FEATURES
s s s s s s s s s s s

DESCRIPTIO

High Efficiency Over Wide Load Current Range 0.8% Output Voltage Accuracy Dual N-Channel MOSFET Synchronous Drivers Pulse Transformer Synchronization Optocoupler Feedback Driver Programmable Current Limit Protection 5% Margin Output Voltage Adjustment Adjustable Overvoltage Fault Protection Power Good Flag Auxiliary 3.3V Logic Supply Available in 16-Lead SSOP and SO Packages

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.

APPLICATIO S
s s s s s

48V Input Isolated DC/DC Converters Isolated Telecommunication Power Systems Distributed Power Step-Down Converters Industrial Control Systems Automotive and Heavy Equipment

TYPICAL APPLICATIO
VIN 36V to 72V

L1

+
Q1 D1 VDD BIAS COUT

+
1 10 VDD CG FG ISNS

R1

R2

T1 Q4 Q2 RPRISEN RSECSEN 11 CSG TG BG CSYNC 15 T2 D2 Q3 2 16 12

PWRGD 8 VFB CFB VCOMP 6

LTC1698

ISNSGND SYNC

ICOMP OVPIN

13 9

RCILM

SG

RSYNC MARGIN

7

VMARGIN VAUX 3.3V 10mA

LT3781

RK REF VFB RE CK

5

OPTODRV PGND 3

VAUX GND 4

14 O.1uF
1681 F01

VC RF

+

CF

ISOLATION BOUNDARY

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

U
VOUT RC CC R5 CCILM R4

U

U

1

LTC1698 Datasheet linear Download PDF

Add this permalink to your bookmarks for future download of LTC1698 datasheet

Permalink: http://datasheet.emcelettronica.com/linear/LTC1698

LTC1698 DATASHEET