A 12V Input, 3.3V Output, 10A Synchronous Buck Controller
System Power Management – DC/DC Controllers
1 INTRODUCTION
The TPS40100EVM-001 evaluation module (EVM) is a synchronous buck converter providing a fixed 3.3V output
at up to 10A from a 12V input bus. The EVM is designed to start up from a single input supply, with no additional
bias voltage required. The module uses a TPS40100 midrange input synchronous buck controller.
2 DESCRIPTION
TPS40100EVM-001 is designed to use a regulated 12V +/-10% (10.8V-13.2V) bus to produce a regulated 3.3V
output at up to 10A of load current. The EVM is designed to demonstrate the TPS40100 in a typical regulated
bus to low-voltage application while providing a number of test points to evaluate the performance of the
TPS40100. The EVM includes features to demonstrate voltage tracking, margin up/down, enable/disable and
power good. A synchronization pin is provided to allow the EVM to be synchronized to an external clock.
2.1 APPLICATIONS
• Non-Isolated Medium Current Point of Load and low voltage bus converters.
• Merchant Power Modules
• Networking Equipment
• Telecommunications Equipment
• DC Power Distributed Systems
2.2 FEATURES
• 10.8V – 13.2V input range
• 3.3V fixed output
• 10 Adc Steady State Output Current
• Output margin up and down support
• Tracking voltage input to support simultaneous sequencing
• Power good indicator
• Frequency synchronization input
• Remote sensing scheme
• 380kHz switching frequency
• Single Main Switch MOSFET and Single Synchronous Rectifier MOSFET
• Single Component Side, surface mount design on a 3.0” x 3.25” evaluation board
• Four Layer PCB with all components on top side
• Convenient test points for probing critical waveforms
• Test points for full loop analysis as well as control to output
2.2.1 USING REMOTE SENSE (J3)
TPS40100EVM-001 provides the user with remote sense capabilities. Remote sense is used to provide more
accurate load regulation by compensating for losses over terminal connections and load wire resistance.
When remote sense is used properly, the converter will regulate the voltage at the point where sense connections
are placed. These remote sense connections are usually placed at the intended load. As the load is increased
the direct output of the converter will rise to compensate for IR losses.
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Caution: long wiring connections can cause the converter to act irregularly. This can show up as pulse width
jitter or an oscillatory effect on the ripple voltage. If this condition occurs, check the set up and make adjustments.
Please see section 5.3.2 in this users guide.
2.2.2 SIMULTANEOUS TRACKING (J3)
The EVM is equipped to provide the ability to demonstrate the tracking feature of the TPS40100. In addition, the
module can be configured to have multiple TPS40100-EVMs track. The voltage tracking function allows the
TPS40100 to track an external ramp (provided on EVM). This tracking feature allows single or multiple modules to
track an external ramp in order to comply with the demands of many microprocessor and memory applications.
Please see section 5.3.3 of the test setup section of the users guide.
2.2.3 ENABLE (SW2)
The EVM is equipped with an enable/disable switch. Please see section 5.3.4 in test set up section of the users
guide. Closing S1 will disable the device by pulling the UVLO pin of the TPS40100 low. Opening the S1 will
enable the device, provided that the appropriate input voltage is present. J3 pin 4 is an enable monitor pin
providing a connection for user observation.
2.2.4 MARGIN UP/DOWN (J4)
The margin up and down feature of the EVM provides the user with the ability to trim or margin the output of the
converter up/down by 3% or 5%. EVM is equipped with convenient jumper settings to give the user the ability to
trim the output voltage. Please see section 5.3.5 in the test set up section of this users guide for more detailed
test setup information.
2.2.5 POWER GOOD (J1)
The EVM contains a power good pin to provide the user with a “power ok” signal. This pin is pulled up through a
resistor to the 5VBP pin of the TPS40100. If any of the following conditions occur the power good pin will pull low;
• Soft-start is active (Vss < 3.5V)
• Tracking is active (Vtrackout>.7V)
• Vfb < 0.61V
• Vfb > 0.77V
• Vuvlo < 1.33V
• Overcurrent condition exists
• Die temperature is greater than 165°C
This pin can be monitored with an oscilloscope to observe its behavior. Please see section 5.3.6 in the test setup
section of the users guide.
2.2.6 SYNCHRONIZTION (J1)
To TPS40100-EVM can be synchronized to an external clock source of a higher frequency than that of the free
running PWM clock. This is a feature that can aid with input filter design. It is recommended that the
synchronization frequency be no more than 120% of the free running frequency. The EVM is configured to a
switching frequency of 370 kHz, so the external frequency into the synchronization pin should be no more than
470 kHz. Please see section 5.3.6 of the test setup section of this users guide.
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3 ELECTRICAL PERFORMANCE SPECIFICATION
Parameter Notes and Conditions Min Typ Max Units
INPUT CHARACTERISTICS
Input Voltage Range 10.813.2 V
Max Input Current VIN = 10.8V, I
No-Load Input Current VIN = 13.2V, I
OUTPUT CHARACTERISTICS
Output Voltage 3.223.30 3.39 V
Output Voltage
Regulation
Line Regulation (10.8V<VIN<13.2V, I
Load Regulation (0A<I
Output Voltage Ripple VIN = 13.2V, I
Output Load Current 0 10 A
Output Over Current 15 A
SYSTEM CHARACTERISTICS
Switching Frequency 350 380 410 kHz
Full Load Efficiency V
LOAD1
The Output Load (LOAD1) should be an Electronic Constant Current Mode Load capable of 0-10Adc @ 3.3V
5.1.4 Recommended Wire Gauge
VIN to J2.
The connection between the source voltage, VIN and J2 of EVM can carry as much as 5 Adc. The minimum
recommended wire size is AWG #16. Shorter lengths of input wire will aid in reducing inductance and provide
better overall performance.
J5 to LOAD1 (Power Pins 2, 3)
The power connection between J5 of EVM and LOAD1 can carry as much as 10 Adc. It is recommended that the
user use AWG#16 wire. It is recommended that the load wires be kept as short as possible. This will aid in
performance, most notably in transient response.
J2 to LOAD1 (Remote Sense)
If remote sense is to be used, ensure that J6 and J7 are in the remote sense enable position (shunt pins 1&2).
Load wires and sense wires should be kept less than 6 inches to ensure proper functionality. The remote sense
wires connecting J5 (pins 1 and 4) and LOAD1 carry less than 1Adc. The minimum recommended wire size is
AWG #22, with the total length of less than 6 inches long.
) should be a 0-15V variable DC source capable of 5Adc. Connect VIN to J2 as
IN
5.1.5 OTHER
FAN
This evaluation module includes components that can get hot to the touch. A small fan capable of 200-400 LFM is
required to reduce component surface temperatures to prevent user injury. The EVM should not be left
unattended while powered or probed while the fan is not running.
OSCILLOSCOPE
A 60MHz or faster oscilloscope can be used to monitor many points on the EVM. For output ripple voltage
measurements the Oscilloscope should be set for 20 MHz bandwidth limiting, 1MΩ impedance, AC coupling,
1µs/division horizontal resolution, 10-20mV/division vertical resolution for taking output ripple measurements.
FUNCTION GENERATOR
A function generator capable of source a 0-5V square wave at frequencies past 400Khz.
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5.2 EQUIPMENT SETUP
5.2.1 Initial EVM Jumper and Switch Settings
Figure 4 is the basic test set up recommended for evaluating the TPS40100EVM-001. EVM is shipped with the
following in the default position:
1. Enable switch (S1) open across pins 2&3. This is the enable position.
2. Tracking enable jumper (J8) has shunt positioned across pins 1&2 disabling the tracking feature.
3. Tracking engage switch (S2) open across pins 2&3. This enables the tracking ramp to charge.
4. Remote sense jumpers (J6 and J7) have shunts positioned across pins 2&3 enabling local
connector sensing.
5. Margin shunts positioned in the margin disable position.
5.2.2 Procedure
1. Working at an ESD workstation, make sure that any wrist straps, bootstraps or mats are
connected referencing the user to earth ground before power is applied to the EVM. Electrostatic
smock and safety glasses should also be worn.
2. Prior to connecting the DC input source, VIN, it is advisable to limit the source current to 5.0A
maximum. Make sure VIN is initially set to 0V and connected as shown in Figure 4.
3. Connect an ammeter between the positive output of the input supply and the positive input of the
EVM. (J2, Pin 1)
4. Connect voltmeter Voltmeter #1 to TP3 and TP4 as shown in Figure 2.1. These are the EVM
input supply monitoring points.
5. Connect LOAD1 to J5 as shown in Figure 2.1. Set LOAD1 to constant current mode to sink 0Adc
before input voltage is applied.
6. Connect voltmeter #2 across TP13 and TP14 as shown in Figure 2.1. This is the EVM output
supply monitoring point. Note: this configuration is local sensing.
7. Remove oscilloscope probe jacket and position probe as shown below in Figure 3. TP17 and
TP18 are implemented to provide the user with the means to achieve good noise immune
measurements of ripple voltage and transient response.
Figure 3: Probe position for ripple measurement
8. Place Fan as shown in Figure 4 and turn on, making sure air is flowing across the EVM.
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+
Voltmeter
#1
-
-
VIN
10.8V -
13.2V
J1
Pow er Good and Syn c In
GND GND
TP3
+
Ammet er
#1
+
J2
-
-
Remot e +Sens e Jumper
TP4
Disabled
J4 Margin Enable
Tracking Engage S2
J8
Tracking Enable
Jumper Disable
Pos i ti on
TEXAS INSTRUMENTS
TPS40100EVM-001
12V to 3.3V @ 10A
HPA089A
Enable S1
TP18
TP17
GND
1
2
3
3
2
1
J5
Tracking In and Enable
Monitor
GND
TP14
J7
--++
4
3
2
+3.3Vout
1
J5
TP13
J6
Probe Tip
Enable SW1
Sw itc h Clos ed = OFF
Sw itch Open = ON
Remot e GND Sense Jumper
Disabled
-
LOAD1
3.3V @
+
Metal Ground Barrel
10A
1MΩ, DC
1V / div
20mHz BW
-
Voltmeter
#2
+
FAN
Figure 4: TPS40100EVM-001 Recommended Test Set-Up
5.2.3 START UP / SHUT DOWN PROCEDURE
1. Increase VIN (V1) from 0V to 12Vdc.
2. Observe that Vout has risen to its nominal voltage.
3. Vary LOAD1 from 0 – 10Adc
4. Vary VIN from 10.8dc to 13.2Vdc
5. Decrease LOAD1 to 0A.
6. Decrease VIN to 0V.
5.2.4 EQUIPMENT SHUTDOWN
1. Shut Down Oscilloscope
2. Shut down LOAD
3. Shut down VIN
4. Shut down FAN
Tip and Barrel Vout ripple and
transient measurement for TP17 and
TP18TP 17
TP18
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5.3 OTHER TESTS
⎣
⎝⎞⎠
5.3.1 ADJUSTING OUTPUT VOLTAGE (R1 & R3)
The regulated output voltage can be adjusted by changing the values of the feedback resistors, R1 and R3. R19
and R17 are located in the feedback to provide the user with positive remote sense and the ability to perform loop
analysis with a frequency/gain analyzer. Resistors R12 and the parallel combination of R1 and R3 are the
dominant resistors associated with setting the output voltage. Listed below are the equations associated for
establishing the output voltage.
Rparallel
Where V
voltages. Table 2 contains values for R1//R3 to generate popular output voltages.
R1 R3⋅()
:=
R1R3+()
= 0.690V, R17 = 49.9Ω, R12 = 18.2k Ω. R1//R3 can be adjusted to provide user defined output
VREF
VoutVref
V
R1//R3
OUT
3.3V 4.82K 12.4 K 7.87 K
2.5V 6.95K 7.15 K 237 K
2.2V 8.33K 8.66 K 205 K
2.0V 9.61K 10.0 K 237 K
1.8V 11.34K 12.1 K 178 K
1.5V 15.55K 16.2 K 365 K
1.2V 24.69K 26.1 K 422 K
R12R17+()
⎡
⋅:=
Rparallel
(Rparallel)
⎤
1+
⎦
R1 R3
Rparallel
⎛
VoutVref−
Vref
R17R12+()⋅:=
Table 2: Adjusting V
5.3.2 Remote Sense Test Set-Up
In order for the remote sense feature of the TPS40100EVM-001 to function properly, it is
essential that the test setup be configured correctly. Use the following steps to set up the remote
sense:
1) Ensure that the remote sense jumpers J7&J8 are shunted across pins 1&2
2) Connect load wires of a max length of 6 inches from pin 2 of J5 (+Vout) to the positive
terminal of the load. Connect same length of wire from pin 3 of J5 (RTN) to the negative
terminal of the load. Be sure to properly gauge the load wires for 10A. AWG#16 is
recommended.
3) Connect sense wire from J5 pin 1 to the positive terminal of the load. This is the +sense
line. Be sure to not exceed 6 inches in length. AWG#22 wire is recommended.
4) Connect sense wire from J5 pin 4 to the negative terminal of the load. This is the –sense
line. 6 inches maximum length. AWG#22 wire is recommended.
5) Monitor voltage at TP13 and TP14 using a voltmeter. This will be the regulated voltage at
the load.
6) Monitor voltage at J5 pins 2, 3. This is the voltage at the output connector. This voltage
will increase based on load.
7) Set load to 0A, constant current. Both monitoring points should read very close to the
same value.
with R1//R3
out
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8) Increase load gradually and observe the difference in voltages present at the monitoring
points. The set voltage (3.3V) will be regulated at the load; this will be noted at TP13 and
TP14. The direct output of the converter (J5 pin 2, 3) will read a higher voltage. As IR
losses increase over load wires and terminals the direct output of the converter will
compensate by raising the voltage to keep within regulation at the load.
Caution: long distance runs from the output of the converter and the load will cause erratic behavior. This can
show up as pulse width jitter or an oscillatory effect on the ripple voltage. If this condition occurs, check the set up
and make adjustments. Please see Figure 5 below for test up.
4123
Input Supply
TP1
TP2
+
-
Tracking Engage S2
J2
Tracking Enable
13 10 74
14
11
15
12 96
Jumper
Disabled
85
1
En ab le S1
J3
Remot e +Sense Jumper
Max 6 " length
J5
Max 6 " length
Max 6 " length
Enabled
-
LOAD1
3.3V @
10A
+
Voltage monitored at the load .
Reading can be taken at the
load if desir ed. NOTE: This is
the point to which the converter
w ill b e regulating to.
-
Voltmeter
#2
+
TP14
4
--++
3
2
1
TP13
2
3
1
-
+
Voltmeter
#3
Voltage monitored at the output
connector .
NOTE: This w ill re ad a higher
value as load c urrent increases.
Voltage w ill be regulated to set
voltage at the LOA D.
Remo t e G ND Sense Jumper
Enabled
Figure 5: TPS40100EVM-001 Recommended Remote Test Set-Up
5.3.3 Voltage Tracking Test Set-Up
The following procedure is for a single EVM demonstration of the track function. Please see Figure 6 below.
1. Shunt pins 2&3 of J8 (Tracking Enable Jumper)
2. Tracking Engage Switch (S2) should be in the closed position.
3. Connect oscilloscope probe to the TRACKING IN pin (J3 pin 1) and the Vout (TP 17&18).
4. Connect load to the output of the EVM and set from 1A – 10A. (User selectable)
5. Power on the EVM with an input voltage of 10.8V – 13.2V. ( Allow for SS voltage to reach 3.5V to
ensure proper tracking performance or wait 1-2 seconds)
6. Open the Tracking Engage Switch (S2) (Shorting pins 1&2 open) and observe how Vout tracks
the TRACKING IN pins rising voltage. Waveforms should be simultaneous.
7. Close the Tracking Engage (S2) (Shorting pins 2&3 open) and observe how Vout tracks the
TRACKING IN pin’s falling voltage. Waveforms should be simultaneous.
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1MΩ, DC
1V / div
60mHz BW
Tracking Engage S2
Clos ed = Dis charge t rac king voltage s ignal.
Open = Charge tracking voltage signal.
To demonstrate multiple EVM (2 modules) tracking the following procedure must be followed to ensure proper
functionality. The second TPS40100 EVM should be configured to a different output voltage.
1. Shunt pins 2&3 of the Tracking Enable Jumper (J8) for both modules.
2. Connect J3 pin 1 of each EVM.
3. Connect TP16 of each EVM. This is the module to module test point. This allows either module to
be the control EVM via S2.
4. Tracking Engage Switch (S2) should be in the closed (shorting pins 2, 3) position on the control
EVMs.
5. Connect oscilloscope probe to the TP17 and 18 of both modules and pin 1 of J3 of one of the
modules. Modules should have a common input voltage and return.
6. Remote sense jumpers (J6&7) should have pins 2&3 shunted. Activating local output sensing.
7. Apply an input voltage of 10.8V to 13.2V.
8. Allow the SS voltage to reach 3.5V.
9. Open the control EVM Tracking Engage Switch (S2) (Opening pins 2, 3) and observe the
monitored points. (Both EVM outputs and the tracking in voltage. Output voltage should follow the
tracking in voltage until reaching the regulation point.
10. Close the Tracking Engage Switch (S2) (Shorting pins 2,3) of the control EVM and observe the
monitored points. (Both EVM outputs and the tracking in voltage) Falling waveforms should be
coincidal.
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TPS40100 EVM #1
1MΩ, DC
1V / div
60mHz BW
Tracking Engage S2
Clo s e d = Dis c harge t rac king voltage signal.
Open = Char ge trac king voltage signal.
Module to
Module TP
+
VIN (10.8 -13.2V)
-
Tracking
Engage S2
TP3
TP16
+
J2
-
TP4
Tracking Engage S2
Closed = Dis ch arge
tracking voltage signal.
Open = Char ge tr acking
voltage signal.
Connector J3
Pin 1 Tracking In
Pin 2,3 Gnd
Pin 4 Enable Mo nitor
Remo te +Sens e Jumper
TP13
--++
TP14
Remo t e GND Sense Jumper
Dis abled
Dis ab led
1
2
J5
3
4
-
+
LOAD1
1.8V @
3A
-
Voltmeter
#2
+
Module to
Module TP
Tracking
Engage S2
TP3
TP16
TP4
+
-
J2
Tracking En a b le
Jumper
4123
J3
J6
Enable S1
Vout
J8
Scope
Jack TP
17&18
+3.3Vout
J7
Figure 9: TPS40100EVM-001 Dual EVM Tracking Test Set-Up
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5.3.4 Enable/Disable Test Set-Up
To begin testing set up EVM according to Figure 4 in the test set up section of the users guide. The switch
(ENABLE S1) provides the ability to enable and disable the device. Please see Figure 10 below for illustration.
Closing S1 will disable the device by pulling the UVLO pin of the TPS40100 low. Opening S1will enable the
device, providing that the appropriate input voltage is present. J3 pin 4 is an enable monitor pin providing a
connection for user observation.
To begin testing set up EVM according to Figure 4. Chose the margin level desired. Connector J4 pins 3,6,12 and
15 are designated pins that can be connected to adjacent Vin pins (2, 5, 11 and 14) of J4 to enable the desired
margin level. Please see Figure 12 (Margin Test Set Up). Example: To margin the unit up 5%, connect jumper
across pins 2 and 3 of J4.
J4 Mar gin Enable
To mar g in t he unit shunt
the associated pins.
Ex ample: Margin up 5%
= shunt pins 2 and 3
13
1074
GNDGND
Tracking Low SW2
TP1
+
-
TP2
J2
Tracking Enable
14
15
Jumper
11
85
129 6
Margin Down 5%
Margin Down 3%
Figure 12: TPS40100EVM-001 Margin Test Set-Up
Margin up 5%.
Channel 1 Vout (looking at transition of voltage 165mV)
Channel 2 Corresponding margin pin
Margin Up 3%
1
2
1
3
2
3
Margin Up 5%
GND GND
Enable SW1
TP16
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Vin = 12V
Iout=10A
Figure 13: Margin up 5%
5.3.6 Power Good And Synchronization Test Set-Up
The TPS40100EVM-100 has the ability to be synchronized to an external clock. To begin testing, set up EVM
according to Figure 4 in this users guide. Connector J1 contains both the power good pin and sync in pin. Power
good can be monitored for its steady state response with a DMM or with an oscilloscope to illustrate its dynamic
response. The Pgood voltage swing will range from 0 – 4.5V dependent on the condition of the output. A low on
this pin dictates a power fault and a high (4.5V) conveys “power ok”.
Pin 4 of J1 is the input for an external clock frequency. To test, set up a function generator to provide a square
wave at a frequency of above 410 kHz and below 480 kHz. Function generator should be set to provide a 0 to 5V
square wave with a 50% duty cycle. Once power is applied to the EVM, apply the external clock to the sync in pin
and observe the gate drive of the low side mosfet (Q2). This should be measured using an oscilloscope
measuring at TP7. Gate drive pulse will coincide with external clock frequency. Please see Figure 14.
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Square Wave, Freq = 120%
SWF, 5V peak
Voltmeter
-
POW ER
GOOD
Tracking Engage S2
Tracking Enable
J2
Jumper
+
GND
GND
En ab le SW1
TP9
LDRV
J1
Pin 1 Po w er Good
Pin 2,3 Gnd
Pin 4 SYNC IN
1MΩ, DC
1V / div
60mHz BW
Func tio n
Generator
SYNC IN
TP1
TP2
GND GND
+
-
Figure 14: TPS40100EVM-001 Power Good and Synchronization Test Set-Up.
Synchronization
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Channel 1 Switchnode voltage
Channel 2 External Clock Signal
Vin = 12V
Iout=10A
Figure 15: Synchronization
6 TPS40100EVM TYPICAL PERFORMANCE DATA &
CHARACTERISTIC CURVES
Figure 16 through Figure 18 present typical performance curves for the TPS40100EVM-001. Since actual
performance data can be affected by measurement techniques and environmental variables, these curves are
presented for reference and may differ from actual field measurements.
The following figures (Figure 19 through 24) show the design of the TPS40100EVM-001 printed circuit board.
The EVM has been designed using a 4-layer, 2oz copper-clad circuit board 3.0” x 3.25” with most of the
components on the top side to allow the user to easily view, probe and evaluate the TPS40100 control IC in a
practical application. Moving components to both sides of the PCB or using additional internal layers can offer
additional size reduction for space constrained systems.
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Figure 19: TPS40100EVM-001 Component Placement (Viewed from Top)
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Figure 20: TPS40100EVM-001 Silkscreen (Viewed from Top)
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Figure 21: TPS40100EVM-001 Top Copper (Viewed from Top)
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Figure 22: TPS40100EVM-001 Layer 2 (X-Ray View from Top)
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Figure 23: TPS40100EVM-001 Layer 3 (X-Ray View from Top)
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Figure 24: Bottom Copper (X-Ray View from Top)
8 LIST OF MATERIALS
Table 3 lists the EVM components as configured according to the schematic shown in Figure 1 and Figure 2.
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30
Date: 05/03/2005
EVM BOM
COUNT RefDes Value Description Size Part Number MFR