User's Guide
SNVA221B – February 2007 – Revised April 2013
AN-1588 LM5001 Evaluation Board
1
Introduction
The LM5001 evaluation board is designed to provide the design engineer with a fully functional isolated
flyback power converter based on current mode control to evaluate the LM5001 switching regulator IC.
The evaluation board provides a 5V output with 1A current capability. The input voltage ranges from 16V
to 42V. The design operates at 250kHz, a good compromise between conversion efficiency and solution
size. The printed circuit board consists of two layers of two ounce copper on FR4 material with a thickness
of 0.062 inches. This application note contains the evaluation board schematic, Bill-of-Materials (BOM)
and a quick setup procedure.
Refer to the LM5001 High Voltage Switch Mode Regulator (SNVS484) data sheet for complete circuit
design information.
The performance of the evaluation board is as follows:
Input Range: 16 to 42V
Output Voltage: 5V, ±2%
Output Current: 0 to 1A
Frequency of Operation: 250 kHz
Board Size: 2.75 X 1.75 X 0.6 inches
Load Regulation: 0.1%
Line Regulation: 0.1%
Over Current Limiting
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SNVA221B – February 2007 – Revised April 2013
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AN-1588 LM5001 Evaluation Board
1
Evaluation Board Schematic
2
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Evaluation Board Schematic
T1
VCC
VIN = 16V ± 42V
J1
R5
20
D1
LPRI = 160 éH
5 8:3:2
R12
10
C11
470 pF
VOUT = +5V
IOUT = 1A
J3
6,7
C1
2.2 éF
C2
2.2 éF
4
3
J2
GND
R6
8.06k
R1
60.4k
J7
ENABLE
C4
0.01 éF
D4
8,9
R13
49.9
C3
0.1 éF
R14
560
C15
2.2 éF
R15
10k
C5
100 pF
SYNC
R3
6.04k
R4
52.3k
2
VIN
8
EN
5
RT
4
GND
LM5001
U1
J6
1
SW
7
COMP
6
FB
3
VCC
C6
1 éF
OPTIONAL
SOFT-START
3
J4
C7
0.01 éF 2
D2
R2
10
C14
1 éF
C12
100 éF
VCC
C9
1 éF
R10
0
R8
249
4
U2
R17
0
R18
2.20k
C16
R16
0.1 PF 4.99k
1
LM431
U3
3
R19
2.20k
2
R7
100k
J5
C19
2200 pF
J8
GND
2kV
IGND
D3
C8
10 éF
Powering and Loading Considerations
Read this entire page prior to attempting to power the evaluation board.
3.1
Quick Setup Procedure
Step 1: Set the input source current limit to 1A. Turn off the input source. Connect the positive output of
the input source to J1 and the negative output to J2.
Step 2: Connect the load, with 1A capability, to J3 for the positive connection and J4 for the negative
connection.
Step 3: The ENABLE pin, J7, should be left open for normal operation.
Step 4: Set the input source voltage to 28V and the load to 0.1A. The load voltage should be in regulation
with a nominal 5V output.
Step 5: Slowly increase the load while monitoring the load voltage at J3 and J4. It should remain in
regulation with a nominal 5V output as the load is increased up to 1 Amp.
Step 6: Slowly sweep the input source voltage from 16V to 42V. The load voltage should remain in
regulation with a nominal 5V output.
Step 7: Temporally short the ENABLE pin (J7) to GND (J5) to check the shutdown function.
Step 8: Increase the load beyond the normal range to check current limiting while the input source is set
to 28V. The output current should limit at approximately 1.9A. The input source current limit should be
increased for this step. Fan cooling is critical during this step.
2
AN-1588 LM5001 Evaluation Board
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Performance Characteristics
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3.2
Air Flow
Prolonged operation at full power and high ambient temperature will cause the thermal shutdown circuit
within the regulator IC to activate. A fan with a minimum of 200 LFM should always be provided.
3.3
Powering Up
Using the ENABLE pin (J7) provided will allow powering up the input source with the current level set low.
It is suggested that the load power be kept low during the first power up. Set the current limit of the input
source to provide about 1.5 times the anticipated wattage of the load. As you remove the connection from
the ENABLE pin to GND (J5), immediately check for 5 volts at the output.
A quick efficiency check is the best way to confirm that everything is operating properly. If something is
amiss you can be reasonably sure that it will affect the efficiency adversely. Few parameters can be
incorrect in a switching power supply without creating losses and potentially damaging heat.
3.4
Over Current Protection
The evaluation board is configured with cycle-by-cycle over-current protection. This function is completely
contained in the LM5001. The Primary current is limited to approximately 1A. This equates to about 1.4A
load current when the input voltage is 16V, and about 2.1A load current when the input is 42V. The
thermal stress on various circuit components is quite severe while in an overloaded condition, therefore
limit the duration of the overload and provide sufficient cooling (airflow).
3.5
Synchronization
A SYNC pin (J6) has been provided on the evaluation board. This pin can be used to synchronize the
regulator to an external clock or multiple evaluation boards can be synchronized together by connecting
their SYNC pins together. Refer to the LM5001 High Voltage Switch Mode Regulator (SNVS484) data
sheet for complete information.
3.6
Flyback Topology
An excellent introduction to the isolated flyback converter is available on the Texas Instruments website.
The Application Note AN-1095(SNVA005) discusses both loop compensation with a secondary side error
amplifier and the phase-shift caused by opto-couplers.
4
Performance Characteristics
Efficiency Plots
Figure 1 shows the conversion efficiency versus output current for several input voltage conditions.
Figure 1. Conversion Efficiency vs Output Current
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AN-1588 LM5001 Evaluation Board
3
Performance Characteristics
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Turn-on Waveform
When applying power to the LM5001 evaluation board a soft-start sequence occurs. Figure 2 shows the
output voltage during a typical start-up sequence.
Conditions: Input Voltage = 28VDC, Output Current = 1A
Trace 1: Output Voltage Volts/div = 1V
Horizontal Resolution = 5ms/div
Figure 2. Voltage During a Typical Start-up Sequence
Output Ripple Waveform
Figure 3 shows the output voltage ripple. This measurement was taken with a very short ground clip and
20 MHz bandwidth limiting.
Conditions: Input Voltage = 28VDC, Output Current = 1A,
Bandwidth Limit = 20MHZ
Trace 1: Output Ripple Voltage Volts/div = 50mV
Horizontal Resolution = 2µs/div
Figure 3. Output Voltage Ripple
4
AN-1588 LM5001 Evaluation Board
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Performance Characteristics
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Primary Switchnode Waveform
Figure 4 shows the typical primary voltage during continuous conduction mode (CCM).
Conditions: Input Voltage = 28VDC, Output Current = 1A,
Bandwidth Limit = 20MHZ
Trace 1: LM5001 SW Pin Volts/div = 10V
Horizontal Resolution = 2µs/div
Figure 4. Primary Voltage During CCM
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AN-1588 LM5001 Evaluation Board
5
Layout and Bill of Materials
5
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Layout and Bill of Materials
The bill of materials is shown in Table 1, including the manufacturer and part number.
Table 1. Bill of Materials
6
DESIGNATO
R
QTY
PART NUMBER
DESCRIPTION
VALUE
C1,2
2
C3225X7R1H225K
CAPACITOR, 1210 X7R CER, TDK
2.2µ, 50V
C3,16
2
C2012X7R2A104K
CAPACITOR, 0805 X7R CER, TDK
0.1µ, 100V
C4, 7
2
C2012X7R2A103K
CAPACITOR, 0805 X7R CER, TDK
0.01µ, 100V
C5
1
C0805C101M5RAC
CAPACITOR, 0805 COG CER, KEMET
100p, 50V
C6, 9, 14
3
C2012X7R1A105K
CAPACITOR, 0805 X7R CER, TDK
1µ, 10V
C8
1
C2012Y5V1A106Z
CAPACITOR, 0805 Y5V CER, TDK
10µ, 10V
C11
1
C0805C471M5RAC
CAPACITOR, 0805 COG CER, KEMET
470p, 50V
C12
1
C1210C107M9PAC3810
CAPACITOR, 1210 X5R CER, KEMET
100µ,6.3V
C15
1
C2012X7R1C225K
CAPACITOR, 0805 X7R CER, TDK
2.2µ, 16V
C19
1
C4532X7R3D222K
CAPACITOR, 1812, X7R CER, TDK
2200p, 2000V
D1
1
CMHSH-3
DIODE, SOD-123 SCHOTTKY, CENTRAL SEMI
200mA, 30V
D2
1
CMMR1U-2
DIODE, SOD-123F, CENTRAL SEMI
1A, 200V
D3
1
BAT54S
DIODE, SOT-23 SCHOTTKY, VISHAY
200mA, 30V
D4
1
CMSH5-40
DIODE, SMC SCHOTTKY, CENTRAL SEMI
5A, 40V
R1
1
CRCW08056042F
RESISTOR, 0805, VISHAY
60.4k
R2,12
2
CRCW080510R0F
RESISTOR, 0805, VISHAY
10
R3
1
CRCW08056041F
RESISTOR, 0805, VISHAY
6.04k
R4
1
CRCW08055232F
RESISTOR, 0805, VISHAY
52.3k
R5
1
CRCW080520R0F
RESISTOR, 0805, VISHAY
20
R6
1
CRCW08058061F
RESISTOR, 0805, VISHAY
8.06k
R7
1
CRCW08051003F
RESISTOR, 0805, VISHAY
100k
R8
1
CRCW08052490F
RESISTOR, 0805, VISHAY
249
R10,17
2
CRCW08050000Z0EA
RESISTOR, 0805, VISHAY
0
R13
1
CRCW080549R9F
RESISTOR, 0805, VISHAY
49.9
R14
1
CRCW08055600F
RESISTOR, 0805, VISHAY
560
R15
1
CRCW08051002F
RESISTOR, 0805, VISHAY
10.0k
R16
1
CRCW08054991F
RESISTOR, 0805, VISHAY
4.99k
R18,19
2
CRCW08052201F
RESISTOR, 0805, VISHAY
2.2k
T1
1
FA2636-AL
POWER XFR, COILCRAFT
160µH
PRIMARY,8:3:2
U1
1
LM5001
REGULATOR, TEXAS INSTRUMENTS
U2
1
PS2811-1M
OPTO-COUPLER, NEC
100% - 200% CTR
U3
1
LM431
REFERENCE, SOT23, TEXAS INSTRUMENTS
2.500V
J1,2,3,4
4
7693
TERMINAL, 6-32 SCREW, 4 PIN, KEYSTONE
SNAP IN, PC MOUNT
J5,6,7,8
4
5002
TERMINAL, SINGLE PIN, KEYSTONE
TESTPOINT, LOOP
AN-1588 LM5001 Evaluation Board
SNVA221B – February 2007 – Revised April 2013
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PCB Layout
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6
PCB Layout
Figure 5. Component Side
Figure 6. Solder Side
SNVA221B – February 2007 – Revised April 2013
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AN-1588 LM5001 Evaluation Board
7
PCB Layout
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Figure 7. Silkscreen
8
AN-1588 LM5001 Evaluation Board
SNVA221B – February 2007 – Revised April 2013
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