LT3710 Datasheet, PDF (1/12 Pages) Linear Technology – Secondary Side Synchronous Post Regulator

LT3710
Secondary Side
Synchronous Post Regulator
FEATURES
s _{Generates a Regulated Auxiliary Output in Isolated}
DC/DC Converters
s _{0.8V ±1.5% Accurate Voltage Reference}
s _{Dual N-Channel MOSFET Synchronous Drivers}
s _{High Switching Frequency: Up to 500kHz}
s _{Programmable Current Limit Protection}
s _{Programmable Soft-Start}
s _{Automatic Frequency Synchronization}
s _{Small 16-Pin Thermally Enhanced TSSOP Package}
U
APPLICATIO S
s _{48V Isolated DC/DC Converters}
s _{Multiple Output Supplies}
s _{Offline Converters}
DESCRIPTIO
The LT^®3710 is a high efficiency step-down switching
regulator intended for auxiliary outputs in single second-
ary winding, multiple output power supplies.
The LT3710 drives dual synchronous N-channel MOSFETs
and achieves high efficiency. With leading edge modula-
tion, it operates well with either primary side peak current
or voltage mode control. It is synchronized to the falling
edge of the transformer secondary winding and can be
used in both single-ended and double-ended isolated
power converter topologies. A high speed operational
amplifier is incorporated to achieve optimum compensa-
tion and fast transient response. A user selectable discon-
tinuous conduction mode improves light load efficiency.
The LT3710 is available in a thermally enhanced TSSOP-16
exposed pad power package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
V_IN
36V
TO 72V
••
TG BG
SG
LT3781
••
V_C
+ ^VREF
– ^VFB
L1
V_CC
BIAS
V_DD
V_COMP
CG
V_FB
FG
I_SNS
LTC1698
SYNC
10k
180pF
10k
10pF
C_S
680pF
0.01µF
V_CC BOOST
SYNC GBIAS
LT3710
CSET TG
SW
ILCOMP BG
SS VA_OUT
BGS
PGND V_FB
CL^– CL⁺
CMDSH-3
4.7µF
0.1µF
3.3k
33nF
OPTODRV
GND
V_OUT1
3.3V
AT 10A
Q1
L2
1.8µH _0.006Ω
V_OUT2
1.8V
+ ^{AT 10A}
Q2 B340A
4700pF
C_OUT2
3.01k 220Ω
2.32k
3710 F01
ISOLATION
BOUNDARY
C_OUT2: POSCAP, 680µF/4V
L2: SUMIDA CEP125-IR8MC-H
Q1, Q2: SILICONIX Si7440DP
PLEASE REFER TO FIGURE 3
IN THE APPLICATIONS SECTION
FOR THE COMPLETE SCHEMATIC
Figure 1. Simplified Single Secondary Winding 3.3V and 1.8V Output Isolated DC/DC Converter
3710f
1