User’s Guide July 2003 SLLU036A
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.
EVM IMPORTANT NOTICE Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not considered by TI to be fit for commercial use.
EVM WARNINGS AND RESTRICTIONS It is important to operate this EVM within the input voltage range of 3 V to 6 V Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM. If there are questions concerning the input range, please contact a TI field representative prior to connecting the input power. Applying loads outside of the specified output range may result in unintended operation and/or possible permanent damage to the EVM.
Trademarks Preface Read This First About This Manual This users guide describes the characteristics, operation, and use of the TPS54314, 3-A, 1.8-V, internally compensated, SWIFT regulator evaluation module (EVM). This user’s guide includes a schematic diagram and bill of materials.
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Contents Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Performance Specification Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contents Figures 1–1 2–1 2–2 2–3 2–4 2–5 2–6 2–7 2–8 2–9 2–10 3–1 3–2 3–3 4–1 Frequency Trimming Resistor Selection Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Connection Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measured Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measured Board Losses . . . . . . . . . .
Chapter 1 Introduction This chapter contains background information for the TPS54314 and support documentation for the TPS54314 evaluation module. The EVM performance specifications are also given. Topic Page 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.2 Performance Specification Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.3 Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Background 1.1 Background The TPS54314EVM evaluation module uses the TPS54314 synchronous buck regulator to provide a 1.8-V output over an input range of 3 V to 6 V and over a load range of 0 A to 3 A. The electrical components of the TPS54314 circuit consume less than 0.6 square inches of board space. Additional pads are provided to support multiple input and output capacitors. A jumper is provided to allow the switching frequency to be easily changed from 350 kHz to 550 kHz.
Modifications 1.3 Modifications 1.3.1 General The TPS54314EVM is designed to demonstrate the small amount of board space taken up by the TPS54314 electrical components. In addition, the EVM can be used to evaluate different output filters by substituting an alternative inductor for L1, or by using the optional pads for capacitors C2 and C10 (see Figure 4–1).
Modifications Table 1–2. Device Modification 1.3.4 Output Voltage (V) Device (U1) 0.9 TPS54311 1.2 TPS54312 1.5 TPS54313 1.8 TPS54314 2.5 TPS54315 3.3 TPS54316 Slow Start The slow start time of the TPS54314EVM can be modified by changing the value of C1. Equation 1 can be used to calculate the value of C1 for a specific slow start time. With C1 left open, the slow start time is typically 3.6 ms. The slow start time can not be made faster than 3.6 ms. T 5 mA C 1 + SS 0.
Chapter 2 Test Setup and Results This chapter describes how to properly connect, setup, and use the TPS54314EVM. It also presents the test results and covers efficiency, output voltage regulation, load transients, loop response, output ripple, input ripple, and start-up Topic Page 2.1 Input/Output Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.2 Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input/Output Connections 2.1 Input/Output Connections The TPS54314EVM has the following four input/output connections: J1 (VI and GND) and J2 (VO and GND). A diagram showing the connection points is shown in Figure 2–1. Connect a power supply capable of supplying 3 A to J1 through a pair of 20 AWG wires. Connect the load to J2 through a pair of 20 AWG wires. Minimize wire lengths to reduce losses in the wires.
Thermal Performance Figure 2–2. Measured Efficiency 100 TA = 25°C Efficiency – % 95 5 VI 90 3.3 VI 85 80 75 0 0.5 1 1.5 2 IL – Load Current – A 2.5 3 Figure 2–3. Measured Board Losses 1.2 TA = 25°C 1 Losses – W 0.8 3.3 VI 0.6 5 VI 0.4 0.2 0 0 0.5 1 1.5 2 IL – Load Current – A 2.5 3 2.3 Thermal Performance The junction temperature is plotted versus the load current with a 25°C ambient temperature in Figure 2–4.
Output Voltage Regulation Figure 2–4. Measured Junction Temperature at 25°C Ambient 55 TA = 25°C TJ – Junction Temperature –°C 50 45 40 3.3 VI 35 5 VI 30 25 20 0 0.5 1 1.5 2 IL – Load Current – A 2.5 3 2.4 Output Voltage Regulation The output voltage load regulation with a 5-V input and a 25°C ambient temperature is shown in Figure 2–5. Over the load range of 0 A to 3 A, the output voltage varies less than 0.35%. Figure 2–5. Measured Load Regulation 1.01 TA = 25°C VI = 5 V 1.
Load Transients 2.5 Load Transients The TPS54314EVM response to load transients is shown in Figure 2–6. The load transient in Figure 2–6 transitions between 0 A and 3 A. The output voltage deviates approximately –60 mV (–3.3%) and 70 mV (3.9%) from its average value as a result of these transients. In Figure 2–6, the output voltage returns to a ±2% regulation band within 30 µs. Figure 2–6. Measured Load Transient Response VI = 5 V 10 µs/div VO = (AC) 50 mV/div IO 2 A/div 2.
Output Ripple Voltage 2.7 Output Ripple Voltage The output ripple voltage is plotted in Figure 2–8 with an input voltage of 5 V and a load current of 3 A. The TPS54314EVM has a typical output voltage ripple of less than 20 mVpp. If the switching frequency is reduced, the output ripple voltage is higher. Figure 2–8. Measured Output Ripple Voltage VI = 5 V IO = 3 A 400 ns/div VO (AC) 10 mV/div 2.8 Input Ripple Voltage The input ripple voltage for a 3-A load is shown in Figure 2–9.
Start-Up 2.9 Start-Up The start-up voltage waveform of the TPS54314EVM, with C1 left open, is shown in Figure 2–10. In Figure 2–10, the input voltage is displayed on channel 3, the output voltage is displayed on channel 1, and the power good signal is displayed on channel 2. Once the input voltage rises above the 2.9-V start-up threshold, the output voltage begins to rise linearly to 1.8 V in 3.6 ms.
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Chapter 3 Board Layout This chapter provides a description of the TPS54314EVM board layout and layer illustrations. Topic 3.1 Page Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Layout 3.1 Layout The top-side (component) layer for the TPS54314EVM is shown in Figure 3–1. The input capacitor (C6), bias decoupling capacitor (C7), and bootstrap capacitor (C5) are all located as close to the IC as possible. The TPS54314EVM PWB consists of two layers of 1.5 oz. copper. The bottom half of the top layer is used as a power ground plane, while the bottom layer is used as a quiet (analog) ground plane.
Layout Figure 3–2.
Layout Figure 3–3.
Chapter 4 Schematic and Bill of Materials The TPS54314EVM schematic and bill of materials are presented in this chapter. Topic Page 4.1 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4.2 Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Schematic 4.1 Schematic Figure 4–1. TPS54314EVM Schematic TP2 VIN J2 2 VI + 1 GND TP3 C3 C6 10 µF JP1 1 U1 TPS54314PWP TP1 AGND RT VSENSE FSEL R1 20 71.5 kΩ 19 18 SS/ENA 17 VBIAS PWRGD 16 BOOT VIN 15 PH VIN 14 PH VIN 13 PH PGND 12 PGND PH 11 PH PGND J3 1 NC TP4 J1 VO 1 2 GND L1 5.2 µH C1 1000 pF + C2 1 TP5 + C4 470 µF 4V 5 C5 0.047 pF TP6 6 7 8 9 10 SS/ENA 2 GND 3 C7 0.
Bill of Materials 4.2 Bill of Materials Table 4–1. TPS54314EVM Bill of Materials Qty Ref Description Size MFR Part Number 1 C1 Capacitor, ceramic, 1000 pF, 25 V, X7r, 10% 603 Murata GRM39X7R102K25 2 C2, C3 Open 7343 (D) 1 C4 Capacitor, POSCAP, 470 µF, 4 V, 40 mΩ, 20% 7343 (D) Sanyo 4TPB470M 1 C5 Capacitor, ceramic, 0.047 µF, 25 V, X7R, 10% 603 Murata GRM39X7R473K25 1 C6 Capacitor, ceramic, 10 µF, 10 V, X5R, 20% 1210 Taiyo Yuden LMK325BJ106MN 1 C7 Capacitor, ceramic, 0.
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