Texas Instruments TPS62125EVM-044 User Manual
User's Guide
SLVU659A–March 2012–Revised March 2012
TPS62125EVM-044 Evaluation Module
This user’s guide describes the characteristics, operation, and use of the Texas Instruments TPS62125
evaluation module (EVM). This EVM is designed to help the user easily evaluate and test the operation
and functionality of the TPS62125. The EVM converts a 4-V to 17-V input voltage to a regulated 3.3-V
output voltage that delivers 300 mA. This user’s guide includes setup instructions for the hardware,
printed-circuit board layouts for the EVM, a schematic diagram, a bill of materials, and test results for the
EVM.
Contents
1 Introduction .................................................................................................................. 2
2 Setup ......................................................................................................................... 2
3 TPS62125EVM-044 Test Results ......................................................................................... 3
4 Board Layout ................................................................................................................ 9
5 Schematic and Bill of Materials .......................................................................................... 11
List of Figures
1 Efficiency (R1, R2, and R3 not installed. JP1 connected between ON and EN.) .................................. 3
2 Load Regulation............................................................................................................. 4
3 Line Regulation With Iout = 250 mA...................................................................................... 4
4 Loop Response With Vin = 12 V and Iout = 250 mA................................................................... 4
5 Input Voltage Ripple With Vin = 12 V and Iout = 250 mA ............................................................. 5
6 Output Voltage Ripple With Vin = 12 V and Iout = 250 mA ........................................................... 5
7 Load Transient Response With Vin = 12 V.............................................................................. 6
8 Start-Up on Vin With 250-mA Load....................................................................................... 6
9 Start-Up on EN With 250-mA Load....................................................................................... 7
10 Shutdown on EN With 250-mA Load..................................................................................... 7
11 Prebias Start-Up and Shutdown on EN With 250-mA Load........................................................... 8
12 Thermal Performance With Vin = 12 V and Iout = 250 mA ........................................................... 8
13 Top Silk Layer............................................................................................................... 9
14 Top Layer .................................................................................................................... 9
15 Bottom Layer............................................................................................................... 10
16 Top Assembly Layer ...................................................................................................... 10
17 TPS62125EVM-044 Schematic.......................................................................................... 11
List of Tables
1 Performance Specification Summary..................................................................................... 2
2 TPS62125EVM-044 Bill of Materials.................................................................................... 12
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Introduction
1 Introduction
The TPS62125 is a 300-mA, synchronous, step-down converter in a 2x2-mm, 8-pin WSON package.
1.1 Background
The TPS62125EVM-044 (PWR044) uses the TPS62125 device and is set to a 3.3-V output. The EVM
operates with full-rated performance with an input voltage between 4 V and 17 V, assuming JP1 is
connected between ON and EN.
The TPS62125 device contains an adjustable enable threshold and adjustable hysteresis feature. Thus,
the input voltage at which the device enables and disables is fully programmable by the user. In the
TPS62125EVM-044, the device is set to turn on at 6 V and turn off at 4 V. This feature can be bypassed
by using jumper JP1, which overrides the programmed threshold voltages.
1.2 Performance Specification
Table 1 provides a summary of the TPS62125EVM-044 performance specifications. All specifications are
given for an ambient temperature of 25°C.
Table 1. Performance Specification Summary
Specification Test Conditions Min Typ Max Unit
Input voltage JP1 connected between EN and ON 4 17 V
Output voltage PWM Mode of Operation 3.3 V
Output current 0 300 mA
Peak efficiency 93.3%
Soft-start time Ramp time of the output voltage 330 µs
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1.3 Modifications
The printed-circuit board (PCB) for this EVM accommodates additional input and output capacitors, as well
as a feedforward capacitor.
1.3.1 Input and Output Capacitors
C3 is provided for an additional input capacitor. This capacitor is not required for proper operation but can
be used to reduce the input voltage ripple.
C4 is provided for an additional output capacitor. This capacitor is not required for proper operation but
can be used to reduce the output voltage ripple and to improve the load transient response. The total
output capacitance must remain within the recommended range in the data sheet for proper operation.
1.3.2 Feedforward Capacitor
C6 is provided for a feedforward capacitor. This capacitor is not required for proper operation but can be
used to improve the transient response. Typically, using a 22-pF feedforward capacitor reduces or
eliminates any output voltage overshoot that may occur at start-up. C6 is located on the back side of the
PCB.
2 Setup
This section describes how to properly use the TPS62125EVM-044.
2.1 Input/Output Connector Descriptions
2
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0.01 0.1 1 10 100 1000
Load Current (mA)
0
10
20
30
40
50
60
70
80
90
100
Efficiency (%)
V = 12 V
IN
V = 17 V
IN
V = 5 V
IN
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J1 – VIN Positive input connection from the input supply for the EVM.
J2 – S+/S- Input voltage sense connections. Measure the input voltage at this point.
J3 – GND Return connection from the input supply for the EVM.
J4 – VOUT Output voltage connection.
J5 – S+/S- Output voltage sense connections. Measure the output voltage at this point.
J6 – GND Output return connection.
J7 – PG/GND The PG output appears on pin 1 of this header with a convenient ground on pin 2.
JP1 – EN EN pin input jumper. Place the supplied jumper across ON and EN to turn on the IC.
Place the jumper across OFF and EN to turn off the IC. Do not install the supplied
jumper to utilize the adjustable enable threshold voltage feature of the IC.
JP2 – PG PG pin pullup voltage jumper. Place the supplied jumper on JP2 to connect the PG pin
Pullup Voltage pullup resistor to Vout. Alternatively, the jumper can be removed and a different
voltage can be supplied on pin 1 to pull up the PG pin to a different level. This
externally applied voltage must remain below 12 V.
2.2 Setup
To operate the EVM, set jumpers JP1 through JP2 to the desired positions per Section 2.1. Connect the
input supply to J1 and J3 and connect the load to J4 and J6.
3 TPS62125EVM-044 Test Results
TPS62125EVM-044 Test Results
This section provides test results of the TPS62125EVM-044.
Figure 1. Efficiency (R1, R2, and R3 not installed. JP1 connected between ON and EN.)
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0
0.2
0.4
0.6
0.8
1
1.2
1.4
0.01 0.1 1 10 100 1000
Load Current (mA)
Load Regulation (%)
V = 5 V
IN
V = 12 V
IN
V = 17 V
IN
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
4 5 6 7 8 9 10 11 12 13 14 15 16 17
Line Regulation (%)
V - Input Voltage - (V)
I
-180
-150
-120
-90
-60
30
0
30
60
90
120
150
180
Phase - deg
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
Gain - dB
100 1k 10k 100k 1M
Frequency - Hz
Phase
Gain
TPS62125EVM-044 Test Results
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Figure 2. Load Regulation
4
TPS62125EVM-044 Evaluation Module SLVU659A–March 2012–Revised March 2012
Figure 4. Loop Response With Vin = 12 V and Iout = 250 mA
Figure 3. Line Regulation With Iout = 250 mA
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SW 5 V/div
lind 200 mA/div
Vin (AC Coupled) 20 mV/div
t - Time - 500 ns/div
Vout (AC Coupled) 20 mV/div
lind 200 mA/div
SW 5 V/div
t - Time - 500 ns/div
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TPS62125EVM-044 Test Results
Figure 5. Input Voltage Ripple With Vin = 12 V and Iout = 250 mA
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Figure 6. Output Voltage Ripple With Vin = 12 V and Iout = 250 mA
5
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Iout 100 mA/div
(150 mA to 250 mA Load Step)
t - Time - 5 s/divm
Vout (AC Coupled) 20 mV/div
EN 2 V/div
t - Time - 100 s/divm
Vin 5 V/div
Vout 1 V/div
PG 2 V/div
TPS62125EVM-044 Test Results
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Figure 7. Load Transient Response With Vin = 12 V
6
TPS62125EVM-044 Evaluation Module SLVU659A–March 2012–Revised March 2012
Figure 8. Start-Up on Vin With 250-mA Load
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