Linear Technology Analog Devices LT8301 Quick setup guide

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dc2138af
DEMO MANUAL DC2138A
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Voltage 10 24 32 V
Standby Current IOUT = 0mA, VIN = 24V, VOUT = 5V 950 µA
Output Voltage VIN = 12V to 32V, IOUT = 6mA to 700mA 4.75 5 5.25 V
Maximum Output Current VIN = 12V
VIN = 24V
700
1000
mA
mA
Output Voltage Ripple (Peak to Peak) VIN = 24V, IOUT = 1A 90 mV
Switching Frequency VIN = 24V, IOUT = 1A 190 kHz
Efficiency VIN = 24V, IOUT = 1A 83.2 %
Description
LT8301
42VIN Micropower Isolated Flyback
Converter with 65V/1.2A Switch
Demonstration circuit 2138A is an isolated flyback con-
verter featuring the LT8301. This demo circuit outputs
5V from a 10V to 32V input, with a nominal of 24V. The
output current capability increases with the input voltage.
The standby input current of the demo circuit is less than
950µA (typical) at VIN = 24V.
The Performance Summary table summarizes the perfor-
mance of the demo board at room temperature. The demo
circuit can be easily modifiedfor differentapplications with
some pre-designed transformers.
The DC2138A needs a very small minimum load (~6mA)
to regulate the output voltage, thanks to the accurate
current limit capability and ultralow switching frequency
of LT8301 at very light load. On the board, a Zener diode
is placed on the output to clamp the voltage to ~5V. This
Zener is optional, and can be replaced with a 0.8k resistor.
The LT8301 is a simple-to-use high-voltage monolithic
isolatedflybackconverter.No thirdwinding oropto-isolator
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
performance summary
is required for regulation. The part sets the isolated output
voltage with a single external resistor and integrates loop
compensationand soft-startcircuitry inside the IC. Bound-
ary mode operation provides a small magnetic solution
with improved load regulation. Low-ripple Burst Mode
®
operation maintains high efficiency at light loads while
minimizing the output voltage ripple. A 1.2A, 65V DMOS
power switch is integrated along with all high-voltage
circuitry andcontrol logicinto a 5-lead ThinSOT™ package.
The LT8301 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for demo circuit 2138A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2138A
Specifications are at TA= 25°C

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DEMO MANUAL DC2138A
Quick start proceDure
Demo circuit 2138A is easy to set up to evaluate the
performance of the LT8301. Refer to Figure 1 for proper
equipment setup and follow the procedure below.
1. With power off, connect the input power supply to the
board through VIN and GND terminals. Connect the
load to the terminals VOUT+ and VOUT– on the board.
2. Turn on the power at the input. Increase VIN slowly to
10V.
NOTE. Make sure that the input voltage is always within
spec. To operate the board with higher input/output
voltage, input capacitor, output capacitor and output
diode with higher voltage ratings are needed.
NOTE. To run overload tests on the demo board at high
line, additional RC snubber might be needed to make
sure the voltage spike at the switching node is always
less than 65V.
3. Check for the proper output voltages. The output should
be regulated at 5V (±5%).
NOTE. The LT8301 requires very small minimum load
to maintain good output voltage regulation. A Zener
diode is placed on the output to clamp the voltage to
~5V. This Zener is optional, and can be replaced with
a 0.8k resistor.
4. Once the proper output voltage is established, adjust
the input voltage and load current within the operating
range and observe the output voltage regulation, tran-
sient, 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 or VOUT capacitor terminals. See Figure 2 for
proper scope probe technique.
Figure 1. Proper Measurement Equipment Setup

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DEMO MANUAL DC2138A
Quick start proceDure
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
Figure 3. Typical Efficiency Curves
Figure 4. Typical Regulation Curves
INPUT OR OUTPUT CAPACITOR
LOAD CURRENT (A)
0
EFFICIENCY (V)
90
80
70
85
75
65
60 0.2 0.6
dc2138a F03
1.0
0.4 0.8
VIN = 12V
VIN = 24V
VIN = 32V
LOAD CURRENT (A)
0.006
V
OUT
(V)
5.25
5.15
5.10
5.05
4.85
5.20
4.95
4.90
5.00
4.80
4.75 0.206 0.606
dc2138a F04
0.406 0.806
VIN = 12V
VIN = 24V
VIN = 32V

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DEMO MANUAL DC2138A
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 Cin CAP., ALUM., 22µF, 50V SUN ELECT., 50CE22BS
2 1 C1 CAP., X7R, 10µF, 50V, 10%, 1210 MURATA, GRM32ER71H106KA12L
3 1 C2 CAP., X5R, 100µF, 6.3V, 20%, 1210 MURATA, GRM32ER6J107ME20L
4 1 D1 DIODE, PMEG3020EH, SOD-123 NXP, PMEG3020EH
5 1 D2 DIODE, 5.6V, SOD-523 DIODES., BZT52C5V6T-7-F
6 1 D3 DIODE., 1N4148WS, SOD323 DIODES., 1N4148WS-7-F
7 1 D4 DIODE, CMHZ5248B, SOD-123 CENTRAL., CMHZ5248B
8 1 R1 RES., CHIP, 1M, 1/8W, 1% 0805 VISHAY, CRCW08051M00FKEA
9 1 R2 RES., CHIP, 210k, 1/10W, 1% 0603 VISHAY, CRCW0603210KFKEA
10 1 R3 RES., CHIP, 154k, 1/10W, 1% 0603 VISHAY, CRCW0603154KFKEA
11 1 T1 TRANSFORMER, 750313974 WURTH, 750313974
12 1 U1 I.C. FLYBACK CONVERTER, SOT23-5 LINEAR TECH., LT8301ES5#PBF
Additional Demo Board Circuit Components
1 0 C3 (OPT) CAP., X7R, 0.22µF, 6.3V, 10%, 0603 MURATA, GRM188R70J224KA
2 0 C4 (OPT) CAP., X7R, 0.01µF, 50V, 10%, 0603 AVX, 06035C103KAT2A
3 0 C5 (OPT) CAP., X7R, 4.7µF, 50V, 10%, 1210 AVX, 12105C475KAT2A
4 0 C6 (OPT) CAP., ALUM., 22µF, 50V SUN ELECT., 50CE22BS
5 0 C7 CAP., X7R, 3300pf, 500V, 10% 1210 AVX, 12107C332KAT2A
6 0 FB1 (OPT) BEAD, 1206 TAIYO YUDEN, MJ3216HS800
7 0 L1 (OPT) IND., 10µH SUMIDA, CDRH4D22HPNP-100MC
8 0 R4 (OPT) RES., CHIP, 2.21k, 1/8W, 1% 0805 VISHAY, CRCW080512K21FKEA
Hardware: For Demo Board Only
1 5 E1-E5 TESTPOINT, TURRET, 0.094" pbf MILL-MAX, 2501-2-00-80-00-00-07-0
2 1 JP1 3 PIN 0.079" SINGLE ROW HEADER SAMTEC, TMM103-02-L-S
3 1 XJP1 SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G
parts List

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DEMO MANUAL DC2138A
VIN
GND
10V - 32V
NOTE: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS AND CAPACITORS ARE 0603.
5.6V
OPTIONAL CIRCUIT
[email protected], VIN>12V [email protected], VIN>24V
SW
VIN
VIN VIN
D2
BZT52C5V6T-7
D2
BZT52C5V6T-7
12
C4 0603 0.01uF,50V C4 0603 0.01uF,50V
R4
OPT
R4
OPT
E5
EN/UVLO
E5
EN/UVLO
R2 210K R2 210K
C7 1210
3.3nF 250V
C7 1210
3.3nF 250V
E1E1
D1
PMEG3020EH
D1
PMEG3020EH
1
2
+
C6 22uF,50V
50CE22BS
+
C6 22uF,50V
50CE22BS
R3 154KR3 154K
D3
1N4148WS
D3
1N4148WS
12
FB1
BEAD
TAIYO YUDEN
FB MJ3216HS800
FB1
BEAD
TAIYO YUDEN
FB MJ3216HS800
R1 1M R1 1M D4
CMHZ5248B
D4
CMHZ5248B
1 2
T1
WURTH, 750313974
T1
WURTH, 750313974
1 46
5
7
8
JP1
EN
DIS
JP1
EN
DIS
1
3
2
OPT
C3
OPT
C3
E2E2
10uF 50V C1 1210 10uF 50V C1 1210
E4
VOUT-
E4
VOUT-
+
22uF 50V Cin
50CE22BS
+
22uF 50V Cin
50CE22BS
C5 1210 4.7uF,50V C5 1210 4.7uF,50V
100uF C2 6.3V 1210 100uF C2 6.3V 1210
E3
VOUT+
E3
VOUT+
U1
LT8301ES5
U1
LT8301ES5
VIN 5
EN/UV
1
RFB
3
GND
2
SW 4
L1
CDRH4D22/HP
SUMIDA
10UH
L1
CDRH4D22/HP
SUMIDA
10UH
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
schematic Diagram

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dc2138af
DEMO MANUAL DC2138A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2014
LT 0314 • PRINTED IN USA
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