NSC LM5027A

National Semiconductor
Application Note 2067
Terry Allinder
June 15, 2010
Introduction
Theory of Operation
The LM5027A evaluation board is designed to provide the
design engineer with a fully functional power converter based
on the Active Clamp Forward topology to evaluate the
LM5027A controller. The evaluation board is provided in an
industry standard quarter-brick footprint.
The performance of the evaluation board is as follows:
Input Operating Range: 36 to 78V (100V peak)
Output Voltage: 3.3V
Output Current: 0 to 30A
Measured Efficiency: 90.5% @ 30A, 92.5% @ 15A
Frequency of Operation: 250 kHz
Board Size: 2.3 X 1.45 x 0.5 inches
Load Regulation: 1%
Line Regulation: 0.1%
Line UVLO, Hiccup Current Limit
A 70% Maximum Duty Cycle
The printed circuit board consists of 6 layers of 2 ounce copper on FR4 material with a total thickness of 0.050 inches.
The unit is designed for continuous operation at rated load at
<40°C and a minimum airflow of 200 CFM.
Power converters based on the Forward topology offer high
efficiency and good power handling capability in applications
up to several hundred Watts. The operation of the transformer
in a forward topology does not inherently self-reset each power switching cycle; a mechanism to reset the transformer is
required. The active clamp reset mechanism is presently finding extensive use in medium level power converters in the 50
to 200W range.
The Forward converter is derived from the Buck topology
family, employing a single modulating power switch. The main
difference between the topologies are, the Forward topology
employs a transformer to provide input / output ground isolation and a step down or step up function.
Each cycle, the main primary switch turns on and applies the
input voltage across the primary winding, which has 12 turns.
The transformer secondary has 2 turns, leading to a 6:1 stepdown of the input voltage. For an output voltage of 3.3V the
required duty cycle (D) of the main switch must vary from approximately 60% (low line) to 25% (high line). The LM5027A
limits the PWM duty cycle output to a maximum of 70% (typical). The maximum duty cycle limits the voltage stress on the
Active Clamp Forward converter MOSFETs. The clamp capacitor along with the reset switch reverse biases the transformer primary each cycle when the main switch turns off.
This reverse voltage resets the transformer. The clamp capacitor voltage is Vin / (1-D).
Feedback from the output is processed by an amplifier and
reference, generating an error voltage, which is coupled back
to the primary side control through an optocoupler. The
LM5027A voltage mode controller pulse width modulates the
error signal with a ramp signal derived from the input voltage.
Deriving the ramp signal slope from the input voltage provides
line feed-forward, which improves line transient rejection. The
LM5027A also provides a controlled delay necessary for the
reset switch. The evaluation board can be synchronized to an
external clock with a recommended frequency range of 275
to 300 kHz.
LM5027A Evaluation Board
LM5027A Evaluation Board
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© 2010 National Semiconductor Corporation
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Schematic
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2
AIR FLOW
An appropriate electronic load, with specified operation down
to 3.0V minimum, is desirable. The resistance of a maximum
load is 0.11Ω. You need thick cables! Consult a wire chart if
needed. If resistor banks are used there are certain precautions to be taken. The wattage and current ratings must be
adequate for a 30A, 100W supply. Monitor both current and
voltage at all times. Ensure there is sufficient cooling provided
for the load.
When applying power to the LM5027A evaluation board certain precautions need to be followed. A failure or mis-connection can present itself in a very alarming manner.
PROPER CONNECTIONS
When operated at low input voltages the evaluation board can
draw up to 3.5A of current at full load. The maximum rated
output current is 30A. Be sure to choose the correct connector
and wire size when attaching the source supply and the load.
Monitor the current into and out of the evaluation board. Monitor the voltage directly at the output terminals of the evaluation board. The voltage drop across the load connecting wires
will give inaccurate measurements; this is especially true for
accurate efficiency measurements.
POWERING UP
Using the shutdown pin provided will allow powering up the
source supply with the current level set low. It is suggested
that the load be kept quite nominal during the first power up.
Set the current limit of the source supply to provide about 1.5
times the wattage of the load. As you remove the connection
from the shutdown pin to ground, immediately check for 3.3
volts at the output.
A most common occurrence, that will prove unnerving, is
when the current limit set on the source supply is insufficient
for the load. The result is similar to having the high source
impedance referred to earlier. The interaction of the source
supply folding back and the evaluation board going into undervoltage shutdown will start an oscillation, or chatter, that
may have highly undesirable consequences.
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.
SOURCE POWER
The evaluation board can be viewed as a constant power
load. At low input line voltage (36V) the input current can
reach 3.5A, while at high input line voltage (78V) the input
current will be approximately 1.5A. Therefore too fully test the
LM5027A evaluation board a DC power supply capable of at
least 80V and 4A is required. The power supply must have
adjustments for both voltage and current. An accurate readout of output current is desirable since the current is not
subject to loss in the cables as voltage is. The power supply
and cabling must present a low impedance to the evaluation
board. Insufficient cabling or a high impedance power supply
will droop during power supply application with the evaluation
board inrush current. If large enough, this droop will cause a
chattering condition upon power up. This chattering condition
is an interaction with the evaluation board undervoltage lockout, the cabling impedance and the inrush current.
OVER CURRENT PROTECTION
The evaluation board is configured with hiccup over-current
protection. In the event of an output overload (approximately
33A) the unit will discharge the softstart capacitor, which disables the power stage. After a delay the soft-start is released.
The shutdown, delay and slow recharge time of the softstart
capacitor protects the unit, especially during short circuit
event where the stress is highest.
LOADING
An appropriate electronic load, with specified operation down
to 3.0V minimum, is desirable. The resistance of a maximum
load is 0.11Ω. You need thick cables! Consult a wire chart if
needed. If resistor banks are used there are certain precautions to be taken. The wattage and current ratings must be
adequate for a 30A, 100W supply. Monitor both current and
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Typical Evaluation Setup
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voltage at all times. Ensure there is sufficient cooling provided
for the load.
Powering and Loading
Considerations
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Start-Up
Power supplies have a soft-start circuit(s) to control their output voltage when input power is applied. The soft-start sequence limits the peak inrush current as the output capacitors
are charged, and prevents the output voltage from overshooting. In most power supplies there are primary side and
secondary side soft-start circuits.
The primary side soft-start circuit is generally in a primary side
controller and the soft-start time is set with an external capacitor. The function of the primary side soft-start circuit is to
slowly increasing the duty cycle of the controller from zero to
the maximum duty cycle. The maximum duty cycle varies
based on the controller and the circuit topology.
The secondary side soft-start circuit connects a resistor/capacitor from the secondary side voltage reference to the
positive input of the error amplifier. The soft-start time is set
by the resistor/capacitor time constant and works by ramping
up the voltage reference on the secondary side error amplifier. The output of the error amplifier is fed across the isolation
boundary to the primary side controller compensation input
which is connected to the controller PWM input. The voltage
at the compensation input increases to a value required for
regulation as determined by the voltage feedback loop. The
secondary side soft-start along with the primary side soft-start
work together to control the duty cycle on start-up to controling
the power supplies output start-up time, and limit the stress
on the power components.
Figure 1 shows the primary and secondary side soft-start sequence using the LM5027A into an electronic load. After Vin
is applied the primary side soft-start ramps up. When the voltage on the LM5027A SS pin reached 1.0 V the output drives
start and power is delivered to the secondary of the transformer. The power supply output rises and the secondary side
soft-start circuit begins to ramp-up. The output of the DC-DC
converter monotonically increased with no overshoot to 3.3 V
out.
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30126303
FIGURE 1. Soft-Start
Pre-Bias Load Start-Up
Figure 2 below shows a typical Forward Converter topology
with an active clamp using self-driven synchronous rectification. It’s simple and very efficient; however there are some
disadvantages when starting this topology into a pre-biased
load. The first occurs because the synchronous rectification
is on the secondary side of the transformer and without adding
intelligence the output current will flow into the converter via
the output choke and the free wheeling MOSFET when the
converter starts-up or shut down with pre-bias voltage.
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FIGURE 2. Typical Forward Converter
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soft-start reaches approximately 4.0V. The OUTSR delay
was added to ensure that the power supply output voltage is
up and in regulation prior to the freewheeling MOSFET being
turned-on, refer to Figure 4 and Figure 5. The OUTSR drive
is soft-started; a capacitor on the SSSR pin is released and
is charged with a 25 µA current source, slowly increasing the
duty cycle of the freewheeling FET’s duty cycle.
OUTSR Drive
The LM5027A has a dedicated pin (OUTSR) to drive the synchronous rectifier free wheeling MOSFET through a drive
transformer as shown in Figure 3. When the converter startsup, the OUTSR drive is held low and the freewheeling MOSFET is turned-off. As a result, no output current will sink into
the converter. The OUTSR is enabled after the primary side
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FIGURE 3. LM5027A Synchronous Rectifier Drive Output (OUTSR)
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30126306
FIGURE 4. LM5027A Drive Timing
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FIGURE 5. LM5027A Soft-Start Waveforms
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Secondary Side Soft-Start
Secondary Side Soft-Start Reset
In a typical DC-DC converter with a 3.3 V output the voltage
reference for the error amplifier is 1.2V. Prior to the power
supply being turned-on and if there is a pre-bias load, the
secondary side soft-start capacitor (CSS) will be pre-charged
to the voltage reference level of 1.2 V (if the pre-bias load >
1.2V), refer to Figure 7. On start-up the primary side soft-start
begins and the output voltage rises from the pre-bias voltage
level to 3.3 V, refer to Figure 6. At the end of the primary side
soft-start period the controller will be at maximum duty cycle
and the output voltage will overshoot until the feedback error
amplifier has a chance to respond and reduce the output voltage to the regulation set point.
When input power is supplied to the LM5027A Evaluation
Board the LM5027A’s internal VCC Regulator turns-on providing power to the VCC pin, the primary side soft-start voltage increases, and the output drives are enabled. When the
drive outputs are enables the voltage on the transformer secondary increases, the Secondary Bias rises supplying voltage
to the reference and error amplifier, refer to Figure 8. During
this time FET Q1 is turned-on holding the reference voltage
at the positive input to the error amplifier low (zero volts).
When the voltage on the secondary bias capacitor (CBIAS) rises above the Zener diode> 3.6 V, the Secondary Bias Power
Good (the collector of Q2) goes high. This turns-off FET Q1
allowing the secondary soft-start capacitor to charge up. This
solution of reseting the soft-start capacitor to zero (0 V) on
start-up works for pre-bias loads as well as loads that do not
need to start into a pre-biased condition. This allows for a
monotonic start-up under both operating modes.
30126308
FIGURE 6. Pre-bias Secondary Side Soft-Start
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30126309
FIGURE 7. VREF with Pre-Bias Load
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30126310
FIGURE 8. Pre-Bias Schematic
the pre-bias source will conduct current through the output
inductor and the self driven gate drive resistors R1 and R2. If
the pre-bias voltage is greater than the Vgs of the synchronous MOSFET (M1), the MOSFET will be turned-on
sinking current into the power supply.
Pre-Bias Load-Synchronous
Forward MOSFET Enabled
The self driven synchronous rectification topology has an issues starting into a pre-bias load. When a pre-bias load is
connected across the power supply output, refer to Figure 9,
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30126311
FIGURE 9. Self Driven with Pre-Bias Load
Where:
Vin = 100 V under transient conditions
n is the transformer turns ratio = 6
A diode D1 is connected from the collector to the emitter of
Q3 to handle any voltage spikes as a result of circuit inductance. Without this diode inductive voltage spike may damage
the Cascod amplifier Q3.
An NPN transistor was use instead of an N-Channel MOSFET
because the Vgs drop, typically 4 to 5 volts; this would reduce
the gates drive voltage to M1. Under minimum input line conditions M1 may not be fully turned-on and there would be an
increase in the I2 x RDS(ON) losses.
Figure 11 shows the start-up waveforms for the Evaluation
board. After the input power is supplied to the Evaluation
board the secondary bias voltage rises, when the secondary
bias is greater than 3.6 V, the Secondary Power Good output
goes high. This turns-on M1 and enables the secondary side
soft-start circuit allowing the output voltage to increase after
Vout > Vpre-bias.
Synchronous Forward MOSFET
Enabled
For the LM5027A Evaluation board we used the Secondary
Bias Power Good signal as a flag to indicate that the primary
sides MOSFETs are switching providing power to the secondary of the transformer T1. When the flag goes high this
indicates that it is time to turn-on the forward conducting
MOSFET M1. The Secondary Bias Power Good signal drives
the base of an NPN transistor (Q3), refer to Figure 10. The
NPN transistor is configured as a Cascod amplifier; when it is
turned-on, the voltage on the secondary of the transformer T1
drives the gate of the synchronous MOSFET, M1. The MOSFET gate drive voltage is:
V-GATE_DRIVE_M1 = V_Secondary_Bias_Power_GoodVBE_Q3
An NPN transistor needs to be selected so that the transistors
collector to emitter voltage under the worst case operating
condition does not exceed it’s VCE ratings, and that the collector current (Icc) can handle the maximum peak current to
drive the gate of MOSFET M1. For the LM5027A Evaluation
board the transistor is a 30 V, 1.5 ampere transistor. The
maximum VCE is:
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30126313
FIGURE 10. Isolated Synchronous MOSFET
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30126314
FIGURE 11. Pre-Bias Load Waveforms
An alternative to using the circuit in Figure 10 is shown in
Figure 12; an additional winding can be added to the power
transformer which can be used to drive the Forward Syn-
chronous Rectifier MOSFET (M1). This is a simple solution
and should not add a lot of complexity to the transformer design.
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30126315
FIGURE 12. Isolated Synchronous MOSFET Drive Using a Transformer
Pre-Bias Load Test Set-Up
Pre-Bias Load Start-Up
Requirements
For the Pre-bias start-up test, the circuit in Figure 13 was
used. An external bias supply, through a 1.0 ohm resistor, was
connected across the output terminals of the Evaluation
Board.
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The Evaluation board Pre-Bias start-up requirements are:
During converter start-up the output shall rise monotonically
and not sink current (into the converter) of more than 50 mA .
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30126316
FIGURE 13. Isolated Synchronous MOSFET Drive Using a Transformer
is less than 50 mA. When the output voltage rise above the
pre-bias voltage there is approximately 400 mA of current out
of (sourced) the Evaluation Board to charge the external 220
µF capacitor. After the external capacitor is charge to 3.3 V
the current out of the power supply drop to approximately 50
mA.
Evaluation Board Results
Figure 14 shows the output of the Evaluation Board starting
with a pre-bias voltage of 2.7 V. Under these conditions the
output voltage starts at 2.7 V and then increases monotonically to 3.3 V. The current into the Evaluation board (sinking)
30126317
FIGURE 14. Pre-Bias StartUp
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Application Schematic: Input 36-76, Voutput 6.3A, 30A
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Performance Characteristics
TURN-ON WAVEFORMS
When applying power to the LM5027A evaluation board a
certain sequence of events occurs. Soft-start capacitor values
and other components allow for a minimal output voltage for
a short time until the feedback loop can stabilize without overshoot. Figure 15 shows the output voltage during a typical
start-up with a 48V input and a load of 5A. There is no overshoot during startup.
OUTPUT RIPPLE WAVEFORMS
Figure 16 shows the transient response for a load of change
from 2A to 25A. The lower trace shows minimal output voltage
droop and overshoot during the sudden change in output current shown by the upper trace.
30126321
Conditions:
Input Voltage = 48VDC
Output Current = 30A
Bandwidth Limit = 25 MHz
Trace 1:
Output Voltage
Volts/div = 50 mV
Horizontal Resolution = 2 µs/div
FIGURE 17.
Figure 17 shows typical output ripple seen directly across the
output capacitor, for an input voltage of 48V and a load of 30A.
This waveform is typical of most loads and input voltages.
Figure 18 and Figure 19 show the drain voltage of Q1 with a
25A load. Figure 18 represents an input voltage of 38V and
Figure 19 represents an input voltage of 78V.
Figure 20 shows the gate voltages of the synchronous rectifiers. The drive from the main power transformer is delayed
slightly at turn-on by a resistor interacting with the gate capacitance. This provides improved switching transitions for
optimum efficiency. The difference in drive voltage is inherent
in the topology and varies with line voltage
30126319
Conditions:
Input Voltage = 48VDC
Output Current = 5A
Trace 1:
Output Voltage
Volts/div = 1.0V
Horizontal Resolution =1 ms/div
FIGURE 15.
30126322
Conditions:
Input Voltage = 38VDC
Output Current = 25A
Trace 1: Q1 Drain Voltage
volts/Div = 20V
Horizontal Resolution = 1 µs/div
30126320
Conditions:
Input Voltage = 48VDC
Output Current = 2A to 25A
Trace1:
Output Voltage
Volts/div = 0.2V
Trace 2:
Output Current
Amps/Div = 5.0 A
Horizontal Resolution = 1 ms/div
FIGURE 18.
FIGURE 16.
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30126323
30126324
Conditions:
Input Voltage = 78VDC
Trace 1: Q1 Drain Voltage
Volts/Div = 20V
Horizontal Resolution = 1 µs/div
Conditions:
Input Voltage = 48VDC
Output Current = 5A
Trace 3: (gate)
Synchronous Rectifier, Q3/Q4
Volts/Div = 2V
Trace 2: (gate)
Synchronous Rectifier, Q5/Q6
Volts/Div = 2V
Horizontal Resolution = 1 µs/div
FIGURE 19.
FIGURE 20.
30126336
FIGURE 21. Efficiency
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18
PART NUMBER
DESCRIPTION
VALUE
C
ITEM
1
C4532X7R2A225M
CAPACITOR, CER, TDK
2.2µ, 100V
C
2
C4532X7R2A225M
CAPACITOR, CER, TDK
2.2µ, 100V
C
3
C4532X7R2A225M
CAPACITOR, CER, TDK
2.2µ, 100V
C
4
C4532X7R2A225M
CAPACITOR, CER, TDK
2.2v, 100V
C
5
APXE4R0ARA681MH80G
CAPACITOR, CER, United Chemi-Con
680µ, 4V
C
6
C1210C476M8PACTU
CAPACITOR,CER,KEMET
47µ, 10V
C
7
C1210C476M8PACTU
CAPACITOR,CER,KEMET
47µ, 10V
C
8
C0603C471J5GAC
CAPACITOR, CER, KEMET
470p, 50V
C
9
C0603C103K3RAC
CAPACITOR, CER, KEMET
0.01µ, 25V
C
10
C0603C223K3RAC
CAPACITOR, CER, KEMET
0.022µ, 25V
C
11
C0603C473K3RAC
CAPACITOR, CER, KEMET
0.047µ, 25V
C
12
C1608X7R1H104K
CAPACITOR, CER, TDK
0.1µ, 50V
C
13
C0603C101J5GAC
CAPACITOR, CER, KEMET
100p, 50V
C
14
C0603C104K3RAC
CAPACITOR, CER, KEMET
0.1µ, 25V
C
15
C3216X7R2E104K
CAPACITOR, CER, TDK
0.1µ, 250V
C
16
C1608X7R1H104K
CAPACITOR, CER, TDK
0.1µ, 50V
C
17
C1210C476M8PACTU
CAPACITOR, CER, TDK
47µ, 10V
C
18
C1210C476M8PACTU
CAPACITOR, CER, TDK
47µ, 10V
C
19
C0603C221J3GAC
CAPACITOR, CER, KEMET
220p, 25V
C
20
OPEN
C
21
C3216X7R2E104K
CAPACITOR, CER, TDK
0.1µ, 250V
C
22
C1608X7R1H104K
CAPACITOR, CER, KEMET
0.1µ, 25V
C
23
C0603C103K3RAC
CAPACITOR, CER, KEMET
0.01µ, 25V
C
24
C0603C473K3RAC
CAPACITOR, CER, KEMET
0.047µ, 25V
C
25
C0603C473K3RAC
CAPACITOR, CER, KEMET
0.047µ, 25V
C
26
C4532X7R3D222K
CAPACITOR, CER, TDK
2200p, 2000V
C
27
GRM188R61E105KA12D
CAPACITOR, CER, MURATA
1.0µ, 25V
C
28
C0603C224K3RAC
CAPACITOR, CER, TDK
0.22µ, 25V
C
29
C0603C102K3RAC
CAPACITOR, CER, KEMET
1000p, 25V
C
30
C0603C102K3RAC
CAPACITOR, CER, KEMET
1000p, 25V
C
31
C0805C471J5GAC
CAPACITOR, CER, KEMET
470p, 50V
C
32
C0805C471F5GAC
CAPACITOR, CER, KEMET
470p, 50V
C
33
C2012X7R2A332K
CAPACITOR, CER, TDK
3300p, 100V
C
34
OPEN
C
71
C4532X7R1E156M
CAPACITOR, CER, TDK
15µ, 25V
C
35
C0603C102K3RAC
CAPACITOR, CER, KEMET
1000p, 25V
C
36
GRM188R61E105KA12D
CAPACITOR, CER, MURATA
1.0u, 25V
D
1
ZHCS350
DIODE, SIGNAL, ZETEX
40V, 500mA
D
2
ZHCS350
DIODE, SIGNAL, ZETEX
40V, 500mA
D
3
ZHCS350
DIODE, SIGNAL, ZETEX
40V, 500mA
D
4
ZHCS350
DIODE, SIGNAL, ZETEX
40V, 500mA
D
5
ZHCS350
DIODE, SIGNAL, ZETEX
40V, 500mA
D
6
CMD2836
DIODE, DUAL SIGNAL, CENTRAL
120V, 200mA
D
7
ZHCS350
DIODE, SIGNAL, ZETEX
40V, 500mA
D
8
ZHCS350
DIODE, SIGNAL, ZETEX
40V, 500mA
D
9
ZHCS350
DIODE, SIGNAL, ZETEX
40V, 500mA
J
1
3104-2-00-01-00-00-08-0
PIN, BRICK, 0.040D, MILL-MAX
MOUNT ON SOLDER
SIDE OF PCB
19
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Bill of Materials
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ITEM
PART NUMBER
DESCRIPTION
VALUE
J
2
3104-2-00-01-00-00-08-0
PIN, BRICK, 0.040D, MILL-MAX
MOUNT ON SOLDER
SIDE OF PCB
J
4
3104-2-00-01-00-00-08-0
PIN, BRICK, 0.040D, MILL-MAX
MOUNT ON SOLDER
SIDE OF PCB
J
5
3231-2-00-01-00-00-08-0
PIN, BRICK, 0.080D, MILL-MAX
MOUNT ON SOLDER
SIDE OF PCB
J
6
3104-2-00-01-00-00-08-0
PIN, BRICK, 0.040D, MILL-MAX
MOUNT ON SOLDER
SIDE OF PCB
J
8
3104-2-00-01-00-00-08-0
PIN, BRICK, 0.040D, MILL-MAX
MOUNT ON SOLDER
SIDE OF PCB
J
9
3231-2-00-01-00-00-08-0
PIN, BRICK, 0.080D, MILL-MAX
MOUNT ON SOLDER
SIDE OF PCB
L
1
SRU1048-6R8Y
INPUT CHOKE, Bourns
6.8uH, 4.8Arms
L
2
7443556130
CHOKE, WURTH
1.2µH, 37A
L
3
SDR0503-332JL
CHOKE, Bourns
3.3mH, 0.045 A
Q
1
SI7846DP
N-FET, SILICONIX
150V, 50m
Q
2
SI3475
P-FET, IR
200V, 1.6
Q
3
SI7866DP
FET, SILICONIX
20V, 3m
Q
4
SI7866DP
FET, SILICONIX
20V, 3m
Q
5
SI7866DP
FET, SILICONIX
20V, 3m
Q
6
SI7866DP
FET, SILICONIX
20V, 3m
Q
7
MMBT2907A
Bipolar, PNP, 60V, 600mA
Q
8
QSX6
Bipolar, NPN, 30V, 1.5A
ROHM
Q
9
2N7002VA
FET, N_Channel, Fairchild
60V 280mA
Q
10
MMBT2907A
Bipolar, PNP, 60V, 600mA
R
1
CRCW120610R0F
RESISTOR
10
R
2
CRCW08059093F
RESISTOR
90.9k
R
3
CRCW06032002F
RESISTOR
20k
R
4
CRCW06034992F
RESISTOR
49.9k
R
5
CRCW06034991F
RESISTOR
4.99k
R
6
CRCW08059093F
RESISTOR
90.9K
R
7
CRCW06031001F
RESISTOR
1K
R
8
CRCW06036191F
RESISTOR
6.19K
R
9
CRCW06035R60F
RESISTOR
5.6
R
10
CRCW060352302F
RESISTOR
52.3K
R
11
CRCW06032002F
RESISTOR
20K
R
12
CRCW06031001F
RESISTOR
1K
R
13
CRCW06035R60F
RESISTOR
5.6
R
14
CRCW120649R9F
RESISTOR
49.9
R
15
CRCW06036R34F
RESISTOR
6.34
R
16
OPEN
R
17
CRCW06032200F
RESISTOR
220
R
18
CRCW06031002F
RESISTOR
10k
R
19
CRCW06034R70F
RESISTOR
4.7
R
20
SHORT (0 Ohms)
RESISTOR, 0 OHMS
0 ohms
R
21
CRCW06031001F
RESISTOR
1K
R
22
CRCW06032000F
RESISTOR
200
R
23
CRCW06031002F
RESISTOR
10k
R
24
CRCW06031502F
RESISTOR
15k
R
25
CRCW06032492F
RESISTOR
24.9k
R
26
CRCW060310R0F
RESISTOR
10
www.national.com
20
PART NUMBER
DESCRIPTION
VALUE
10
R
27
CRCW060310R0F
RESISTOR
R
28
CRCW06031001F
RESISTOR
1k
R
29
CRCW06032002F
RESISTOR
20.0k
R
30
CRCW06031002F
RESISTOR
10.0k
R
31
CRCW06034990F
RESISTOR
499
R
32
OPEN
R
33
SHORT (0 Ohms)
RESISTOR, 0 OHMS
0 ohms
R
34
CRCW1218110ROFKEK
RESISTOR
10, 1W
R
35
CRCW1218110ROFKEK
RESISTOR
10, 1W
R
36
CRCW06031001F
RESISTOR
1k
R
37
CRCW06033011F
RESISTOR
3.01k
R
38
CRCW06034990F
RESISTOR
499
R
39
CRCW06034702F
RESISTOR
47k
R
40
CRCW06034702F
RESISTOR
47k
R
41
CRCW06034702F
RESISTOR
47k
R
42
CRCW06031002F
RESISTOR
10k
R
T1
NTCG164BH103H
NTC, 10k @25°C, [email protected]°C, TDK
10k
T
1
HA4000-Al
POWER XFMR W/AUX, COILCRAFT
12:2
T
2
DA2319-ALB
Gate Drive, Coilcraft
T
3
P8208T, Pulse
CURRENT XFR, PULSE ENG
U
1
LM5027AMH
CONTROLLER, NATIONAL SEMI
U
2
PS2811-1M
OPTO-COUPLER, NEC
U
3
LM8261M5
OPAMP, NATIONAL SEMI
U
4
LM4040CEM3-4.1
REFERENCE, NATIONAL SEMI
U
5
LM4041CEM3-1.2
REFERENCE, NATIONAL SEMI
Z
2
MM5Z3V6
DIODE, ZENER 3.6V
21
100:1
Fairchild
www.national.com
AN-2067
ITEM
AN-2067
Printed Circuit Layout
30126326
Tassy
30126327
Bottom Layer
www.national.com
22
AN-2067
30126328
Bottom Silk Layer
30126329
Mid 1 Layer
23
www.national.com
AN-2067
30126330
Mid 2 Layer
30126331
Mid 3 Layer
www.national.com
24
AN-2067
30126332
Mid 4 Layer
30126333
TASSY
25
www.national.com
AN-2067
30126334
Top Layer
30126335
Top Silk Layer
www.national.com
26
AN-2067
Notes
27
www.national.com
LM5027A Evaluation Board
Notes
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