DC1557A - Demo Board

DEMO CIRCUIT 1557A
QUICK START GUIDE
LT3748EMS
LT3748EMS
Non-Opto Isolated Flyback Converter
DESCRIPTION
Demonstration circuit 1557A is an Non-Opto Isolated Flyback Converter featuring LT3748EMS. It is designed for
12V output from a 30V to 75V DC input. The output current is up to 1A. The part senses the isolated output voltage directly from the primary side flyback waveform during the off time of the power switch. No third winding,
opto-coupler or signal transformer is required for regulation. A minimum load of approximately 2% of maximum
load is required on the output. Table 1 summarizes the
performance of the demo board.
The demo circuit can be easily modified for applications
of different input, and output voltages/currents. Some
pre-designed EP10, EP13 transformers from vendors
such as Wurth Electronics, Sumida, Pulse Engineering
and Coilcraft can be assembled on the board.
The LT3748EMS is a high input voltage isolated flyback
controller operating with input supply voltages from 5V to
100V. The LT3748EMS utilizes boundary mode operation
Table 1.
to provide a high efficiency, small size solution with improved load regulation of ±5% over the full line, load and
temperature ranges. The LT3748EMS is well suited for a
wide variety of industrial, automotive, medical, telecom,
data-com applications, where regulated isolated output is
required.
The LT3748EMS datasheet gives a complete description
of the part, operation and application information. The
datasheet should be read in conjunction with this quick
start guide for Demo Circuit 1557A.
Design files for this circuit board are available. Call
the LTC Factory.
, LTC, LT and LTM are registered trademarks of Linear Technology Corporation.
Performance Summary of DC1557A (TA = 25oC)
PARAMETER
Minimum Input Voltage
Maximum Input Voltage
Output Voltage, VOUT
Output Current, IOUT
CONDITION
VIN=30V~75V
IOUT=20mA~1A
VIN=30V~75V
VALUE
30V
75V
12.0V ±5%
1.0A
QUICK START PROCEDURE
Demo circuit 1557A is easy to set up to evaluate the performance of the LT3748EMS. Refer to Figure 1 for proper
measurement equipment setup and follow the procedure
below.
1. With power off, connect the input power supply to VIN
and GND.
2. Connect the load to the terminals VOUT+ and VOUTon the board. Apply 20mA load to the output.
3. Turn on the power at the input. Increase VIN to 30V.
NOTE. Make sure that the input voltage does not exceed 75V.
4. Check for the proper output voltages. The output
should be regulated at 12V (±5%).
NOTE. If there is no output, temporarily disconnect the power
supply. Make sure that the load is connected with correct polarity.
If the output voltage is out of spec, make sure minimum load
current is applied to the output, the load is not set too high, and
the current of power supply is below current limit.
1
LT3748EMS
5. Once the proper output voltage is established, adjust
the input and load within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters.
NOTE. When measuring the input or output voltage ripples, care
must be taken to avoid a long ground lead on the oscilloscope
probe. Measure the input or output voltage ripple by touching the
probe tip directly across the VIN and GND, or VOUT+ and VOUTterminals. See Figure 2 for proper scope probe technique.
Figure 1. Proper Measurement Equipment Setup
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
2
LT3748EMS
3
LT3748EMS
Linear Technology Corporation
Bill of Materials
LT3748EMS
Item Qty
Demo Bd. #1557A
Reference
Part Description
REQUIRED CIRCUIT COMPONENTS:
Manufacturer / Part #
NIC, NACEW100M100V6.3X8TR13F
1
1
C1
CAP., ELECTROLYTIC, 10uF 100V, 6.3x8
2
1
C2
CAP., X7R, 2.2uF 100V, 1210
TDK, C3225X7R2A225M
3
1
C3
CAP., X7R, 47uF 16V, 2220
TDK, C5750X7R1C476M
4
1
C7
CAP., X7R, 0.1uF 16V, 0402
TDK, C1005X7R1C104K
5
1
C8
CAP., C0G, 470pF 50V, 0402
TDK, C1005C0G1H471M
6
1
C10
CAP., X7R, .1uF 100V, 0805
TDK, C2012X7R2A104K
7
1
C11
CAP., X7R, 6800pF 25V, 0402
TDK, C1005X7R1E682K
8
1
C12
CAP., X7S, 1uF 100V, 0805
TDK, C2012X7S2A105K
9
1
C13
CAP., C0G, 10pF 50V, 0402
TDK, C1005C0G1H100M
10
1
C16
CAP., X5R, 4.7uF, 25V, 0805
TDK, 2012X5R1E475K
11
1
D1
SCHOTTKY BARRIER RECTIFIER 2.1A,SMA-DIODE
VISHAY, VS-10MQ100NPbF
12
1
D2
SCHOTTKY MINI, SOD323
DIODES/ZETEX., BAV20WS-7-F
13
1
D3
DE, SCHOTTKY MINI, SOD323
DIODES/ZETEX., 1N5711WS-7-F
14
1
Q1
MOSFET N-CH, POWER33
FAIRCHILD SEMI., FDMC2674
15
1
R1
RES., CHIP, 12KΩ, 0402
VISHAY, CRCW040212K0FKED
16
1
R3
RES., CHIP, 357KΩ, 0402
NIC, NRC04F3573TRF
17
2
R4,R8
RES., CHIP, 2KΩ, 1206
VISHAY, CRCW12062K00FKEA
18
1
R5
RES., CHIP, 6.04KΩ, 0402
NIC, NRC04F6041TRF
19
1
R6
RES., CHIP, 16.5KΩ, 0402
VISHAY, CRCW040216K5FKED
20
1
R7
RES., CHIP, 121KΩ, 0603
VISHAY, CRCW0603121KFKED
21
1
R9
RES., CHIP, 57.6KΩ, 0402
VISHAY, CRCW040257K6FKED
22
1
R10
RES., SENSE, 0.03, 0805
VISHAY, WSL0805R0300FEA
23
2
R11,R12
RES., CHIP, 0Ω, 0402
VISHAY, CRCW04020000Z0ED
24
1
T1
XFMR, FLYBACK, TRANS-PULSE-EP13
25
1
LINEAR TECH., LT3748EMS
1
0
U1
IC., LT3748EMS, MSE16(12)
ADDITIONAL DEMO BOARD CIRCUIT COMPONENTS:
C4 (OPT)
CAP., X7R, 0.01uF 50V, 0603
2
0
C5 (OPT)
CAP., X7R, 4.7uF 100V, 1210
TDK, C4532X7S2A475M
3
0
C6 (OPT)
CAP., 22uF 100V
OPT
4
0
C14 (OPT)
CAP., 0.033uF, 2220
OPT
5
0
C15 (OPT)
CAP., NPO, 47pF 50V, 0402
OPT
6
0
FB1 (OPT)
BEAD, 1206
TAIYO YUDEN, FB MJ3216HS800
7
0
L1 (OPT)
IND, PWR, 10UH, L-CDRH4D22/HP
SUMIDA, CDRH4D22HPNP-100MC
8
0
R2 (OPT)
RES., CHIP, 0603
HARDWARE-FOR DEMO BOARD ONLY:
OPT
1
5
E1,E2,E3,E4,E5
MILL-MAX, 2501-2-00-80-00-00-07-0
4
TP, TURRET, 0.094"
PULSE, PA2467NL, or WURTH, 750311439
TDK, C1608X7R1H103K
Similar pages