Texas Instruments LMZ35003EVM-001 User manual

Using the LMZ35003EVM-001
Evaluation Module
User's Guide
Literature Number: SNVU294
JULY 2013

User's Guide
SNVU294–JULY 2013
LMZ35003EVM-001
Simple Switcher® Power Module Evaluation Module
The LMZ35003EVM-001 evaluation module is designed as an easy-to-use platform for evaluating the
features and performance of the Simple Switcher® power module. This user's guide provides information
on the correct usage of the LMZ35003EVM-001 and an explanation of the test points on the board.
1 Description
The LMZ35003EVM-001 evaluation module (EVM) features a LMZ35003 device configured for operation
from a 7-V to 50-V input supply. The output voltage can be set to one-of-five popular values by using a
simple configuration jumper. Similarly, the switching frequency can be set to one-of-four values by use of
a jumper. The full, 2.5-A-rated output current can be supplied by the EVM. A minimal amount of input and
output capacitance is used on the board. Component pads are provided for additional input and output
capacitors if desired. A simple 5-V pull-up supply for the PWRGD pin is provided on the EVM. It is
powered from the input voltage supply. Test points are provided that allow measurement of efficiency,
power dissipation, input ripple, output ripple, line and load regulation, soft-start behavior, transient
response, and undervoltage lockout (UVLO) behavior. The EVM uses a recommended printed-circuit
board (PCB) layout that maximizes thermal performance and minimizes output ripple and noise.
2 Getting Started
The host power supply is connected to the EVM at terminal block TB1. The Vin and GND terminals are
clearly marked. The terminal block can accept up to 16 AWG wire. For a complete evaluation, the host
supply must be adjustable up to 50 V and be capable of delivering at least 3 A of current. The output of
the EVM is presented to terminal block TB2. An electronic or resistive load can be connected to the block.
Input and output voltage test points are provided near the terminal blocks. These test points are intended
to be used as voltage monitoring points where voltmeters can be connected to measure Vin and Vout. Do
not use these test points as the input supply or output load connection points. The PCB traces connecting
to the test points are not designed to support high currents.
Before applying power, ensure that the Fsw select (J3) and Vout select (J4) jumpers are present and
properly positioned for the intended output voltage. SeeTable 1 for the recommended jumper setting.
Always remove power before changing the jumper settings.
Once the jumper settings have been confirmed, set the host input supply to a voltage level at least 3 volts
higher than the selected output voltage or 7 V, whichever is greater. (The minimum input voltage
specification for the LMZ35003 is (Vout + 3) or 7 V, whichever is greater.) Turn the host supply on, and
then confirm that the selected output voltage is obtained.
Table 1. Output Voltage and Switching Frequency Jumper Settings
Vout Select, J2 (V) Fsw Select, J1 Minimum VIN (V)
2.5 400 kHz 7
3.3 400 kHz 7
5 500 kHz 8
12 800 kHz 15
15 1 MHz 18
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www.ti.com Schematic
3 Schematic
Figure 1. LMZ35003EVM-001 Schematic
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Test Point Descriptions www.ti.com
4 Test Point Descriptions
Wire-loop test points have been provided as convenient connection points for digital voltmeters (DVM) or
oscilloscope probes to aid in the evaluation of this device. A description of each test point follows.
VIN Input voltage monitoring point. Connect a DVM to this point for measuring efficiency.
VOUT Output voltage monitoring point. Connect a DVM to this point for measuring efficiency,
line regulation, and load regulation.
TB3 VIN Connect an oscilloscope probe with a short grounding tip to this pair of holes to
measure input ripple voltage.
TB4 VOUT Connect an oscilloscope probe with a short grounding tip to this pair of holes to
measure output ripple voltage and transient response.
SS/TR Monitor the voltage on the soft-start capacitor here. Also use it as an input for the
Tracking function.
INH/UVLO Ground this terminal to inhibit power conversion. When open, the voltage on this pin is
the voltage of the UVLO resistor divider network.
RT/CLK Monitors the RT pin (timing resistor) of the device. Adding resistance to ground to this
pin raises the switching frequency. The pin also can be driven by a 3.3-V, logic-level
clock signal to set the switching frequency. A frequency range of 400 kHz to 1 MHz is
supported.
PWRGD Monitors the Power Good pin. A weak pullup to 5.1 V is provided on the EVM. PWRGD
is high when the output voltage is within ±8% of its nominal value.
GND Ground points for meters of oscilloscope probes.
PH Via test point for monitoring the Phase pin (switching node) of the device with an
oscilloscope. This test point can be used to measure the switching frequency of the
regulator. Use only a x10 oscilloscope probe to monitor this point. The operation of the
device can be affected by the stray capacitance of conventional cables or x1 probes.
VS+ This signal monitors the point where the feedback-loop monitors the output voltage.
This point can be used to remote sense the output voltage at an external load. It also
can be used as an injection point for a frequency-response loop analyzer. The injection
signal can be applied across the SENSE+ and VOUT test points.
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Scope Measurements: Vin = 12 V, Vout = 5 V, Iout = 1.0 A
Ch.3> PH Node
Scope Measurements: Vin = 12 V, Vout = 5 V, Iout = 300 mA
Ch.3> PH Node
www.ti.com Operation Notes
5 Operation Notes
The UVLO threshold of the factory-stock EVM is approximately 6.5 V with a 0.5-V hysteresis. The input
voltage must be above the UVLO threshold before power conversion will begin. The UVLO threshold is set
by resistors R10 and R11. See the data sheet for information on setting the UVLO voltage.
Once the input voltage rises above the UVLO threshold, power conversion begins and the output voltage
ramps to its final value in approximately 10 ms. If desired, this soft-start interval can be increased by
adding capacitance at location C4 on the bottom side of the EVM. This location is not populated on the
factory-stock EVM.
The LMZ35003 is a nonsynchronous buck regulator. This means that the power stage can only source
current and does not sink current. This also means at lighter loads, the waveform observed on the PH test
node exhibits considerable ringing as shown in Figure 2. This is normal behavior. At heavier loads, the PH
waveform becomes rectangular, as shown in Figure 3. When attempting to measure switching frequency,
it is recommended that a load of 1 A or greater be applied to ensure that an accurate reading is obtained.
The LMZ35003 is not designed to endure a sustained short circuit on its output. It can survive momentary
shorts (< 5 seconds), but sustained short circuits may cause permanent damage to the device.
Figure 2. PH Node at 300-mA Load Figure 3. PH Node at 1-A Load
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EVM Assembly Drawings and PCB Layout www.ti.com
6 EVM Assembly Drawings and PCB Layout
Figure 4 through 9 show the design of the LMZ35003EVM-001 printed circuit board.
Figure 4. Top Layer
Figure 5. Layer 1
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www.ti.com EVM Assembly Drawings and PCB Layout
Figure 6. Layer 2
Figure 7. Layer 3
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EVM Assembly Drawings and PCB Layout www.ti.com
Figure 8. Layer 4
Figure 9. Bottom Layer
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www.ti.com List of Materials
7 List of Materials
Table 2. EVM List of Material(1)(2)(3)(4)
COUNT REF DES DESCRIPTION PART NUMBER MFR
0 C10 Capacitor, aluminum, 35 VDC, ±20%, 100 µF, 6.3 mm x 11 mm ESMG350ELL101MF11D United ChemiCon
1 C11 Capacitor, ceramic, 100 V, 5%, NP0, 100 pF, 0603 C1608C0G2A101F TDK
3 C1-3 Capacitor, ceramic, 100 V, 5%, X7R, 2.2 µF, 1210 C3225X7R2A225K TDK
0 C4 Capacitor, ceramic, 100 V, 10%, X7R, 2200 pF, 0603 STD STD
1 C5 Capacitor, aluminum, 100 V, 20%, 22 µF, 0.200 inch Dia. EKZE101ELL270MHB5D United ChemiCon
4 C6-9 Capacitor, ceramic, 25 V, 10%, X7R, 22 µF, 1210 GRM32ER71E226KE15L MuRata
1 D1 Diode, Zener, 5.1 V, 500 mW, SOD-123 DDZ9689-7 Diodes Inc
1 J1 Header, male 2x4 pin, 100-mil spacing, 0.20 inch x 0.40 inch PEC04DAAN Sullins
1 J2 Header, male 2x5 pin, 100-mil spacing, 0.100 inch x 5 inch x 2 PEC05DAAN Sullins
inch
1 R1 Resistor, chip, 1/10 W, 1%, 10 Ω, 0603 STD STD
1 R10 Resistor, chip, 1/10 W, 1%, 174 kΩ, 0603 STD STD
1 R11 Resistor, chip, 1/10 W, 1%, 40.2 kΩ, 0603 STD STD
1 R12 Resistor, chip, 1/10 W, 1%, 49.9 kΩ, 0603 STD STD
1 R13 Resistor, chip, 1/10 W, 1%, 24.9 kΩ, 0603 STD STD
1 R2 Resistor, chip, 1/10 W, 1%, 36.5 kΩ, 0603 STD STD
1 R3 Resistor, chip, 1/10 W, 1%, 88.7 kΩ, 0603 STD STD
2 R4 R6 Resistor, chip, 1/10 W, 1%, 21.5 kΩ, 0603 STD STD
1 R5 Resistor, chip, 1/10 W, 1%, 9.76 kΩ, 0603 STD STD
1 R7 Resistor, chip, 1/10 W, 1%, 1.13 M, 0603 STD STD
1 R8 Resistor, chip, 1/10 W, 1%, 267 kΩ, 0603 STD STD
1 R9 Resistor, chip, 1/10 W, 1%, 178 kΩ, 0603 STD STD
(1) These assemblies are ESD sensitive, ESD precautions shall be observed. Use of no clean flux is not acceptable.
(2) These assemblies must comply with workmanship standards IPC-A-610 Class 2.
(3) Ref designators marked with an asterisk ('**') cannot be substituted. All other components can be substituted with equivalent MFG's
components.
(4) Install label after final wash. Text shall be 8 pt font. Text shall be per Table 3.
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List of Materials www.ti.com
Table 2. EVM List of Material(1)(2)(3)(4) (continued)
COUNT REF DES DESCRIPTION PART NUMBER MFR
2 TB1-2 Terminal block, 2 pin, 15 A, 5.1 mm, 0.40 inch x 0.35 inch ED120/2DS OST
0 TB3-4 Header, male 2 pin, 100-mil spacing, 0.100 inch x 2 inch PEC02SAAN Sullins
7 TP1-2 TP7-8 Test point, white, thru hole, 5012, 0.125 inch x 0.125 inch 5012 Keystone
TP10-11 TP13
6 TP3-6 TP9 Test point, black, thru hole, 5011, 0.125 inch x 0.125 inch 5011 Keystone
TP14
1 U1 7 V to 50 V Input, 2.5-A Non-synchronous Buck, QFN LMZ35003RKG TI
1 PCB PCB, FR4, 0.062 inch, 1 oz copper all layers, 4.0 inch x 2.0 PWR087 TI
inch
2 Shunt(5) Connector, jumper, shorting, gold flash, 2 (1 x 2) x 100 mil SPC02SYAN Sullins
4 Standoff Bumpon hemisphere 0.44 inch x 0.20 inch clear, 0.440 inch x SJ-5303 3M
0.200 inch
1 -- Label, 1.25 inch x 0.25 inch THT-13-457-10 Brady
(5) Place in position over pins 1 and 2 on both J1 and J2
Table 3. Label Text
ASSEMBLY NUMBER TEXT
PWR087-001 LMZ35003EVM-001
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