TPS769xx SOT-23 LDO Linear Regulator Evaluation Module User’s Guide February 2000 Mixed-Signal Products SLVU024
IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete.
Preface Related Documentation From Texas Instruments J TPS76901, TPS76912, TPS76915, TPS76918, TPS76925, TPS76927, TPS76928, TPS76930, TPS76933, TPS76950 Ultra Low-Power 100-mA Low-Dropout Linear Regulators (TI Literature Number SLVS203) provides detailed information on the TPS769xx family of devices. FCC Warning This equipment is intended for use in a laboratory test environment only.
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Running Title—Attribute Reference Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Output Voltages Greater Than VREF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Output Voltages Less Than VREF . . . . . .
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Chapter 1 Introduction The TPS76901EVM–127, the TPS76918EVM-127, and the TPS76933EVM-127 LDO regulator modules provide the user with cost-effective solutions for providing power to various low-voltage options. These EVMs are pin-compatible with standard 3-terminal type regulators. The EVMs are set up as 1-V, 1.8-V, and 3.3-V output at 100 mA. Various options can be implemented with the board to give a range of output voltages from 0 to 5.5 V. Topic Page 1.1 Introduction . . . . . . . . . . . . . . . .
Introduction 1.1 Introduction Low cost and simplicity of design make LDO regulators popular solutions in low-power step-down applications where lack of isolation from the input source is not a concern. Applications of the EVM include single DSP C5400 device, digital camera, medical test equipment, cell phones, consumer audio equipment, and battery backup electronics. Figure 1–1 shows the schematic of the TPS76901EVM-127 configured for a 1-V output. The TPS76933EVM–127 (3.
Output Voltages Greater Than VREF 1.2 Output Voltages Greater Than VREF For applications requiring an output voltage greater than the internal reference voltage (VFB) of 1.224 V, a standard linear regulator circuit with an external voltage divider is all that is necessary.
Output Voltages Less Than VREF 1.3 Output Voltages Less Than VREF Applications requiring a lower output voltage than the internal reference voltage needs additional circuitry. The backside components shown in the upper section of figure 1 along with the deletion of R4 will implement this option. The backside components function as a second (but fixed) voltage source to artificially increase the voltage at the feedback terminal, thus requiring less output voltage to satisfy the error amplifier.
Fixed Voltage Options 1.4 Fixed Voltage Options The TPS76918EVM–127 (Vout = 1.8 V) and the TPS76933EVM–127 (Vout = 3.3 V) fixed voltage options are also available. Both of these EVMs use only 4 components (see Figure 1–2) and can be used as a three terminal regulator. Figure 1–2. Fixed Voltage Version of the TPS769xxEVM–127 U1 TPS769XX IN (3 – 6 V) 1 IN J1 R1 Open 2 3 OUT J3 5 R3 0 GND EN NC/FB 4 Vfb IREF + C3 4.7 µ F C1 1.
1-6 Introduction
Chapter 2 Board Layers and Assembly Drawings This chapter shows the board layers and assembly drawings of the TPS769xx EVM. Topic Page 2.1 Board Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–2 2.2 Assembly Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Board Layers 2.1 Board Layers Figure 2–1. Top Layer Figure 2–2.
Board Layers Figure 2–3. Bottom Layer (Top View) Figure 2–4.
Board Layers Figure 2–5.
Assembly Drawings 2.2 Assembly Drawings Figure 2–6. Top Assembly Figure 2–7.
2-6 Board Layers and Assembly Drawings
Chapter 3 Testing This chapter provides details on testing the TPS76901–EVM–127 Topic 3.1 Page Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing 3.1 Testing Power Supply 5-V, 150-mA Supply – + Load 0 – 100 mA 3.2 Test Setup Test Procedure (for TPS76901EVM-127, VO = 1 V) 1) Connect test setup as shown in the previous illustration. Set load to zero current. Set input voltage to 5 V and apply. 2) Verify output voltage is 1.00 V ±50 mV. 3) Adjust load for 100 mA and again verify output voltage is 1.00 V ±50 mV.
Test Setup Table 3–1. Bill Of Materials REF DES C1 QTY 1 PART NUMBER DESCRIPTION C2 C3 MFG Capacitor, ceramic, 1 µF, 16 V, +80%–20%, Y5V ECJ-2VF1C105Z Panasonic Not used 1 C3 (Alt) SIZE 805 603 TPSC475K035R0600 Capacitor, tantalum, 4.7 µF, 35 V, 20% AVX C ECST1AC226R Capacitor, tantalum, 22 µF, 10 V, 20% Panasonic C C4 1 GRM39X7R102K050A Capacitor, ceramic, 1000 pF, 50 V, 10%, X7R muRata 603 J1 3 CA26DA-D36K-0FA Clip, surface-mount, 0.040″ board, 0.
Test Setup Figure 3–2. Quiescent Current vs Output Current QUIESCIENT CURRENT vs OUTPUT CURRENT 2 VADJ = 1 V VIN = 5 V I Q– Quiscent Current – mA 1.8 1.6 1.4 1.2 1 0 20 80 40 60 IO – Output Current – mA 100 Figure 3–3. Line Regulation LINE REGULATION 1.05 VO – Output Voltage – V 1.045 1.04 II=15 mA 1.035 II=99.4 mA 1.03 1.025 1.
Test Setup Operation of the 1-V EVM with input voltages from 2.7 V to 3 V requires increasing the bias current for the TL431. Changing R5 to 180 Ω accomplishes this at the expense of higher quiescent currents. Figures 3–4 and 3–5 show the results of this modification. Figure 3–4. Quiescent Current vs Output Current QUIESCIENT CURRENT vs OUTPUT CURRENT 16 VIN = 5 V R5=180 Ω I Q– Quiscent Current – mA 14 12 10 8 6 4 2 0 0 20 40 60 80 100 IO – Output Current – mA Figure 3–5. Line Regulation from 2.
3-6 Testing
