NSC LMZ22005 Evaluation board to be an easy-to-use platform to evaluate Datasheet

National Semiconductor
Application Note 2085
Alan Martin
March 27, 2011
Introduction
Board Specifications
The LMZ23605/03, LMZ22005/03 evaluation boards are designed to be an easy-to-use platform to evaluate the full
capabilities of this family of SIMPLE SWITCHER® power
modules. The PCB construction has excellent thermal performance and includes extra locations for optional components that may not be required in the end application.
The LMZ23605/03 can accept an input voltage rail between
6V and 36V and the LMZ22005/03 can accept an input voltage rail between 6V and 20V. The devices can deliver an
adjustable and highly accurate output voltage as low as 0.8V
and as high as 6V. The control architecture is constant frequency PWM with emulated current mode sensing. The control loop operates well with low ESR output capacitors such
as ceramics or specialty polymer. The precision enable input
allows for programmable UVLO on the input supply or flexibility in sequencing. The external soft-start capacitor facilitates controlled output rise time at startup. The module family
is a reliable and robust solution with cycle-by-cycle valley current limit to protect for over current or short-circuit faults.
Additionally there is thermal shutdown protection, and they
will start up into a pre-biased output. The free-running switching frequency is 812 kHz (typ) and a 650 kHz to 950 kHz
synchronization range is supported.
•
•
•
•
•
•
VIN = 6V to 36V (LMZ22005/03 limited to 20V)
Enable UVLO = 5.7V
VOUT = 3.3V
IOUT = 0 to 5A (LMZ23603 and LMZ22003 limited to 3A)
θJA = 12°C / W, θJC = 1.9°C/W
PCB designed on four layers; Inner are 2 oz; Outer are 3
oz.
• Measures 3.5 in. x 3.5 in. (8.9 cm x 8.9 cm) and is 62mil
(.062”) thick of FR4 laminate material
• Max ambient temp of 70°C at full 5A load (12 Vin)
For additional circuit considerations refer to the Applications
Section of the LMZ23605/03 or LMZ22005/03 data sheets.
For negative output voltage connections follow the method
shown in AN-2027.
LMZ23605/03, LMZ22005/03 Evaluation Board
LMZ23605/03, LMZ22005/03
Evaluation Board
30131601
FIGURE 1. Evaluation Board Simplified Schematic
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© 2011 National Semiconductor Corporation
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LMZ23605 3.3Vout Efficiency @ 25°C Ambient
LMZ23605 3.3Vout Dissipation @ 25°C Ambient
100
8
80
70
60
8 Vin
12 Vin
20 Vin
24 Vin
30 Vin
36 Vin
50
40
0
6
DISSIPATION (W)
EFFICIENCY (%)
36 Vin
30 Vin
24 Vin
20 Vin
12 Vin
8 Vin
7
90
5
4
3
2
1
0
1
2
3
4
OUTPUT CURRENT (A)
5
0
1
2
3
4
OUTPUT CURRENT (A)
30131637
LMZ23605 3.3Vout Dissipation @ 85°C
100
8
90
80
70
9 Vin
12 Vin
20 Vin
24 Vin
30 Vin
36 Vin
50
40
0
1
2
3
4
OUTPUT CURRENT (A)
6
DISSIPATION (W)
EFFICIENCY (%)
36 Vin
30 Vin
24 Vin
20 Vin
12 Vin
9 Vin
7
60
5
30131638
LMZ23605 3.3Vout Efficiency @ 85°C
5
4
3
2
1
0
5
0
1
2
3
4
OUTPUT CURRENT (A)
30131630
5
30131631
LMZ23605 Load and Line Regulation @ 25°C Ambient
LMZ23605 Current Limit VOUT = 3.3V
1.002
8
7
1.001
6
CURRENT (A)
OUTPUT VOLTAGE (V)
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Performance Characteristics
1.000
9 Vin
12 Vin
20 Vin
24 Vin
30 Vin
36 Vin
0.999
0.998
0
1
2
3
4
OUTPUT CURRENT (A)
Output Current
5
4
3
2
Input Current
1
0
5
0
4
8
12 16 20 24 28 32 36
INPUT VOLTAGE (V)
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30131639
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Output Ripple VOUT = 3.3V
IOUT = 5A, BW to 20 MHz
Output Ripple VOUT = 3.3V
IOUT = 5A, BW to 250 MHz
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LMZ23605 Load Step Response VIN = 12V
VOUT = 3.3V, 0.5A to 5A Step
LMZ23603 Load Step Response VIN = 12V
VOUT = 3.3V, 0.5A to 3A Step
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30131619
LMZ23605 Start-up
LMZ23605 Pre-biased startup
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AN-2085
J1 and J2 are for input and output noise measurement. To
implement this feature, populate the 1uF blocking capacitors
and the 49.9 ohm source resistors. Install Amphenol coax
connectors type 112404 (Digikey #ACX1051).The added RC network forms a 2X scope probe when used in conjunction
with an input termination of 50 ohms at the oscilloscope, providing 5 times more sensitivity than a conventional 10x probe.
J3 is for connection to a frequency response analyzer such
as A/P Instruments (Ridley) or Venable Industries products.
Refer to the FRA operating manual for this connection. Note:
Do not place any type of shorting jumper to these three posts
as that will cause a malfunction.
Inductor current can be monitored by connecting a loop of
between module pin 7 (Vout) and the Co array. First cut the
top side conducting etch between the two vias adjacent to pin
7, then install a 5” loop of 22 ga insulated wire in the two vias.
Monitor the inductor sense loop with an AC/DC oscilloscope
current probe.
The Vin input plane has solder mask openings where an input
LC network can be placed to accommodate improved differential mode and conducted EMI performance.
Additional component mounting pads are available to experiment with alternative Cin and Cout combinations. See Figure
6 for corresponding schematic locations.
Notes
Solder turrets are located on the edge of the PCB assembly
for evaluation hookup to bench test equipment. The Enable
input turret is designed for direct connection to the VIN turret.
There is a resistive divider implemented on the board that establishes the 5.5V precision UVLO level of the board. A
common user change to this divider is to raise the value of
RENT to increase the operating UVLO to that of the target application. Refer to the respective data sheet for calculation.
Note that if in the end application the module pin 3 enable
voltage does not exceed 5.5V at maximum Vin, then enable
clamp zener D1 can be omitted.
Each implementation of the evaluation board is preset to 3.3V
output; with current rating and maximum input voltage rating
dictated by the model of module installed. A common user
change is to adjust the output voltage for different requirements. A table of suggested resistor pairs are listed in Figure
1 for quick reference.
Locations are provide for testing the operation as a coincident
turn-on tracking supply (slave). To implement this feature, remove CSS and install Rtkt and Rtkb. Calculations are suggested in the respective data sheets.
A turret is also provided for applying a clock to synchronize
the module switching frequency anywhere between 650 kHz
and 950 kHz. Note that a sustained “logic one” on this input
corresponds to “zero hertz” and will cause the module to stop
switching.
PCB View and layout diagrams
Gerber and CAD files can be downloaded from the LMZ23605 /03, LMZ22005/03 respective product folders.
30131614
FIGURE 2. Top View of Assembly
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30131609
FIGURE 3. Top Layer
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FIGURE 4. Internal Layer I (Ground)
Heat Sinking Layer
5
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30131611
FIGURE 5. Internal Layer II (Ground and Routing)
Heat Sinking Layer
30131612
FIGURE 6. Bottom Layer (Ground)
Heat Sinking Layer
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30131613
FIGURE 7. LMZ2360x / LMZ2200x PCB CAD package schematic
DNP = Component not populated
7
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AN-2085
TABLE 1. Bill of Materials, VIN = 6V to 36V, VOUT = 3.3V, IOUT (MAX) = 5A (3A)
Note: The same BOM applies to all implementations
Designator
Description
Case Size
Manufacturer
Manufacturer P/N
Quantity
U1
SIMPLE SWITCHER®
TO-PMOD-7
National
Semiconductor
LMZ23605TZ or
LMZ23603TZ or
LMZ22005TZ or
LMZ22003TZ
1
CIN1
CIN5
CO1
CO6
0.047 µF, X7R, 50V
1206
Yageo America
CC1206KRX7R9BB473
4
CIN2
CIN3
10 µF, X5R, 50V
1210
Taiyo Yuden
UMK325BJ106MM-T
2
CIN6 OPT
150 µF,Aluminum
Electrolytic, 50V
G
Panasonic
EEE-FK1H151P
1
CO2 OPT
100 µF, X5R, 6.3V
1210
TDK
C3225X5R0J107M
1
CO5
220 µF, Specialty
Polymer, 6.3V
Panasonic
EEF-UE0J221LR
1
CFF
DNP
CSS
0.47µF, X7R, 16V
0805
AVX
0805YC474KAT2A
1
D1
5.1V 200mW
SOD-323
Diodes Inc.
MMSZ5231BS-7-F
1
RENB
12.7 kΩ
0805
Panasonic
ERJ-6ENF1272V
1
RENT
42.2 kΩ
0805
Panasonic
ERJ-6ENF4222V
1
RENH
100 Ω
0805
Vishay-Dale
CRCW0805100RFKEA
1
RFBT
3.32 kΩ
0805
Vishay-Dale
CRCW08053K32FKEA
1
RFBB
1.07 kΩ
0805
Vishay-Dale
CRCW08051K07FKEA
1
RFRA
23.7 Ω
0805
Vishay-Dale
CRCW080523R7FKEA
1
RFF
DNP
RSN
1.50 kΩ
0805
Vishay-Dale
CRCW08051K50FKEA
1
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LMZ23605/03, LMZ22005/03 Evaluation Board
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