Evaluation Board for the ADP1740/ADP1741 EVAL-ADP1740/ADP1741 FEATURES GENERAL DESCRIPTION Input voltage range: 1.6 V to 3.6 V Output current range: 500 μA to 2 A Output voltage accuracy: ±2% Operating temperature range: −40°C to +125°C The ADP1740/ADP1741 evaluation board is used to demonstrate the functionality of the ADP1740/ADP1741 series of linear regulators. Simple device measurements, such as line and load regulation, dropout, and ground current, can be demonstrated with just a single voltage supply, a voltmeter, a current meter, and load resistors. For more details about the ADP1740/ADP1741 linear regulators, visit www.analog.com. 07154-001 EVALUATION BOARD DIGITAL PICTURE Figure 1. Rev. 0 Evaluation boards are only intended for device evaluation and not for production purposes. Evaluation boards are supplied “as is” and without warranties of any kind, express, implied, or statutory including, but not limited to, any implied warranty of merchantability or fitness for a particular purpose. No license is granted by implication or otherwise under any patents or other intellectual property by application or use of evaluation boards. Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Analog Devices reserves the right to change devices or specifications at any time without notice. Trademarks and registered trademarks are the property of their respective owners. Evaluation boards are not authorized to be used in life support devices or systems. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. www.analog.com Tel: 781.329.4700 Fax: 781.461.3113 ©2008 Analog Devices, Inc. All rights reserved. EVAL-ADP1740/ADP1741 TABLE OF CONTENTS Features .............................................................................................. 1 Dropout Voltage ............................................................................5 General Description ......................................................................... 1 Ground Current Measurement ........................................................6 Evaluation Board Digital Picture .................................................... 1 Ground Current Consumption ...................................................6 Revision History ............................................................................... 2 PCB Layout Considerations .............................................................7 Evaluation Board Hardware and Schematic ................................. 3 Thermal Considerations...............................................................7 Evaluation Board Configurations .............................................. 3 Ordering Information .................................................................... 11 Output Voltage Measurement ......................................................... 4 Bill of Materials ........................................................................... 11 Line Regulation ............................................................................. 5 Ordering Guide .......................................................................... 11 Load Regulation............................................................................ 5 ESD Caution................................................................................ 11 REVISION HISTORY 11/08—Revision 0: Initial Version Rev. 0 | Page 2 of 12 EVAL-ADP1740/ADP1741 EVALUATION BOARD HARDWARE AND SCHEMATIC EVALUATION BOARD CONFIGURATIONS The ADP1740/ADP1741 evaluation boards are shipped with different components depending on which version is ordered. Figure 2 shows the schematic of this evaluation board configuration. Table 1 lists and describes the hardware components. Components common to all versions are C1, C2, C3, R3, J1, J2, and J3. TP1 TP3 VOUT = 0.5V(1+R1/R2) ADP1741 ONLY VIN = 1.8V 16 C1 4.7µF VIN 13 14 15 C2 4.7µF VIN VOUT VOUT TP4 1 2 R3 100kΩ J1 3 VIN VOUT VIN VOUT VIN VOUT EN ADP1740: SENSE/ ADP1741: ADJ 12 11 J2 R1 10 TP5 TP6 4 PG TP2 PG 5 GND 6 9 R2 NC SS 7 TP7 8 TP8 C3 10nF NC = NO CONNECT TP9 07154-002 J3 Figure 2. Evaluation Board Schematic Table 1. Evaluation Board Hardware Components Component U1 1 C1 C2 C3 R1, R2 R3 J1 J2 J3 1 Function Linear Regulator Input Capacitor Output Capacitor Soft Start Capacitor Output Voltage Set Pull-Up Resistor Jumper Jumper Jumper Description ADP1740 or ADP1741 Low Dropout Linear Regulator. 4.7 μF Input Bypass Capacitor. 4.7 μF Output Capacitor. Required for stability and transient performance. 10 nF Soft Start Capacitor. Not Installed. 100 kΩ Pull-Up Resistor for Power Good (PG). Jumper Connects EN to VIN for Automatic Startup. Jumper Connects SENSE to VOUT (for ADP1740 only). Jumper Connects Soft Start Capacitor C3. Component varies depending on the evaluation board model ordered. Rev. 0 | Page 3 of 12 EVAL-ADP1740/ADP1741 OUTPUT VOLTAGE MEASUREMENT Figure 3 shows how the evaluation board can be connected to a voltage source and a voltmeter for basic output voltage accuracy measurements. A resistor can be used as the load for the regulator. Ensure that the resistor has a power rating adequate to handle the power expected to be dissipated across it. An electronic load can be used as an alternative. In addition, ensure that the voltage source can supply enough current for the expected load levels. Follow these steps to connect to a voltage source and voltage meter: 2. Connect the negative terminal (−) of the voltage source to one of the GND pads on the evaluation board. Connect the positive terminal (+) of the voltage source to the VIN pad of the evaluation board. 4. 5. Connect a load between the VOUT pad and one of the GND pads. Connect the negative terminal (−) of the voltmeter to one of the GND pads. Connect the positive terminal (+) of the voltmeter to the VOUT pad. The voltage source can now be turned on. If J1 is inserted (connecting EN to VIN for automatic startup), the regulator powers up. If the load current is large, connect the voltmeter as close as possible to the output capacitor to reduce the effects of IR drops. VOLTAGE SOURCE VOLTMETER 1.99711 + – + – LOAD 07154-003 1. 3. Figure 3. Output Voltage Measurement Setup Rev. 0 | Page 4 of 12 EVAL-ADP1740/ADP1741 1.520 For line regulation measurements, the regulator output is monitored while its input is varied. For good line regulation, the output must change as little as possible with varying input levels. 1.515 1.510 1.505 1.500 1.495 1.490 1.485 1.480 10 LOAD = 10mA LOAD = 100mA LOAD = 400mA LOAD = 800mA LOAD = 1.2A LOAD = 2A 1.510 Figure 5. Output Voltage vs. Load Current DROPOUT VOLTAGE Dropout voltage can be measured using the configuration shown in Figure 3. Dropout voltage is defined as the input-tooutput voltage differential when the input voltage is set to the nominal output voltage. This applies only for output voltages above 1.6 V. Dropout voltage increases with larger loads. 1.505 1.500 1.495 1.490 1.480 1.8 07154-004 1.485 For more accurate measurements, use a second voltage meter to monitor the input voltage across the input capacitor. The input supply voltage may need to be adjusted to account for IR drops, especially if large load currents are used. Figure 6 shows a typical curve of dropout voltage measurements with different load currents. 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 VIN (V) Figure 4. Output Voltage vs. Input Voltage 0.25 LOAD REGULATION The input voltage must be held constant during this measurement. The load current can be varied from 500 μA to 2 A. Figure 5 shows the typical load regulation performance of an ADP1740 with fixed 1.5 V output for an input voltage of 1.9 V. 0.20 DROPOUT VOLTAGE (mV) For load regulation measurements, the output of the regulator is monitored while the load is varied. For good load regulation, the output must change as little as possible with varying loads. 1.6V 0.15 0.10 2.5V 0.05 0 1 10 100 LOAD CURRENT (mA) 1k Figure 6. Dropout Voltage vs. Load Current Rev. 0 | Page 5 of 12 10k 07154-006 OUTPUT VOLTAGE (V) 1.515 10k 100 1k LOAD CURRENT (mA) 1.520 07154-005 To ensure that the device is not in dropout mode during this measurement, VIN must be varied between VOUTNOM + 0.4 V (or + 1.6 V, whichever is greater) and VINMAX. For example, for an ADP1740 with fixed 1.5 V output, VIN needs to be varied between 1.9 V and 3.6 V. This measurement can be repeated under different load conditions. Figure 4 shows the typical line regulation performance of an ADP1740 with fixed 1.5 V output. OUTPUT VOLTAGE (V) LINE REGULATION EVAL-ADP1740/ADP1741 GROUND CURRENT MEASUREMENT Follow these steps to connect to a voltage source and ammeter: 2. 3. 4. Connect the positive terminal (+) of the voltage source to the VIN pad on the evaluation board. Connect the positive terminal (+) of the ammeter to one of the GND pads of the evaluation board. Connect the negative terminal (−) of the ammeter to the negative (−) terminal of the voltage source. Connect a load between the VOUT pad of the evaluation board and the negative (−) terminal of the voltage source. The voltage source can now be turned on. If J1 is inserted (EN is connected to VIN for automatic startup), the regulator powers up. Ground current measurements can determine how much current the internal circuits of the regulator are consuming while the circuits perform the regulation function. To be efficient, the regulator needs to consume as little current as possible. Typically, the regulator uses the maximum current when supplying its largest load level (2 A). Figure 7 shows the typical ground current consumption for various load levels at VIN = 1.9 V. When the device is disabled (EN = GND), ground current drops to less than 2 μA. 1600 1400 1200 1000 800 600 400 200 0 10 10k 100 1k LOAD CURRENT (mA) Figure 7. Ground Current vs. Load Current VOLTAGE SOURCE AMMETER 0.00112 – – + LOAD 07154-007 + Figure 8. Ground Current Measurement Rev. 0 | Page 6 of 12 07154-008 1. GROUND CURRENT CONSUMPTION GROUND CURRENT (µA) Figure 8 shows how the evaluation board can be connected to a voltage source and an ammeter for ground current measurements. A resistor can be used as the load for the regulator. Ensure that the resistor has a power rating adequate to handle the power expected to be dissipated across it. An electronic load can be used as an alternative. Ensure that the voltage source used can supply enough current for the expected load levels. EVAL-ADP1740/ADP1741 PCB LAYOUT CONSIDERATIONS Heat dissipation from the package can be improved by increaseing the amount of copper attached to the pins of the ADP1740/ ADP1741. However, as shown in Table 2, a point of diminishing returns is eventually reached, beyond which an increase in the copper size does not yield significant heat dissipation benefits. Here are a few general tips when designing PCBs: • Place the input capacitor as close as possible to the VIN and GND pins. • Place the output capacitor as close as possible to the VOUT and GND pins. • Place the soft start capacitor close to the SS pin. • Connect the load as close as possible to the VOUT and SENSE pins (ADP1740) or to the VOUT and ADJ pins (ADP1741). 07154-010 Use of 0603 or 0805 size capacitors and resistors achieves the smallest possible footprint solution on boards where area is limited. Figure 10. Typical Board Layout, Bottom Side THERMAL CONSIDERATIONS To guarantee reliable operation, the junction temperature of the ADP1740/ADP1741 must not exceed 125°C. To ensure that the junction temperature stays below this maximum value, the user needs to be aware of the parameters that contribute to junction temperature changes. These parameters include ambient temperature, power dissipation in the power device, and thermal resistance between the junction and ambient air (θJA). The θJA value is dependent on the package assembly compounds used and the amount of copper to which the GND pins of the package are soldered on the PCB. Table 2 shows typical θJA values of the 16-lead LFCSP for various PCB copper sizes. Table 3 shows the typical ΨJB value of the 16-lead LFCSP. 07154-009 Table 2. Typical θJA Values Figure 9. Typical Board Layout, Top Side Copper Size (mm2) 01 100 500 1000 6400 1 θJA (°C/W), LFCSP 130 80 69 54 42 Device soldered to minimum size pin traces. Table 3. Typical ΨJB Values Copper Size (mm2) 100 500 1000 Rev. 0 | Page 7 of 12 ΨJB (°C/W) @ 1 W 32.7 31.5 25.5 EVAL-ADP1740/ADP1741 PD = [(VIN − VOUT) × ILOAD] + (VIN × IGND) (2) where: VIN and VOUT are the input and output voltages, respectively. ILOAD is the load current. IGND is the ground current. TJ = TA + {[(VIN − VOUT) × ILOAD] × θJA} 80 LOAD = 250mA LOAD = 500mA 60 LOAD = 100mA 40 20 LOAD = 10mA 1.0 1.5 2.0 2.5 3.0 VIN – VOUT (V) Figure 12. 500 mm2 of PCB Copper, TA = 25°C, LFCSP 140 JUNCTION TEMPERATURE, TJ (°C) (3) As shown in Equation 3, for a given ambient temperature, inputto-output voltage differential, and continuous load current, a minimum copper size requirement exists for the PCB to ensure that the junction temperature does not rise above 125°C. Figure 11 through Figure 16 show junction temperature calculations for different ambient temperatures, load currents, VIN to VOUT differentials, and areas of PCB copper. MAX JUNCTION TEMPERATURE MAX JUNCTION TEMPERATURE 120 LOAD = 1A 100 LOAD = 500mA LOAD = 250mA 80 60 LOAD = 100mA 40 20 LOAD = 10mA 0 0.5 120 1.0 1.5 2.0 2.5 3.0 3.0 VIN – VOUT (V) LOAD = 2A Figure 13. 0 mm2 of PCB Copper, TA = 25°C, LFCSP 100 LOAD = 1A 140 MAX JUNCTION TEMPERATURE 80 60 LOAD = 250mA LOAD = 100mA 40 20 LOAD = 10mA 0 0.5 1.0 1.5 2.0 2.5 VIN – VOUT (V) Figure 11. 6400 mm2 of PCB Copper, TA = 25°C, LFCSP 3.0 JUNCTION TEMPERATURE, TJ (°C) LOAD = 500mA 07154-034 JUNCTION TEMPERATURE, TJ (°C) LOAD = 1A 0 0.5 Power dissipation due to ground current is quite small and can be ignored. Therefore, the junction temperature equation can be simplified as follows: 140 LOAD = 2A 100 07154-035 where: TA is the ambient temperature. PD is the power dissipation in the die, given by 120 07154-036 (1) MAX JUNCTION TEMPERATURE 07154-037 TJ = TA + (PD × θJA) JUNCTION TEMPERATURE, TJ (°C) 140 The junction temperature of the ADP1740/ADP1741 can be calculated from the following equation: 120 LOAD = 2A LOAD = 500mA 100 LOAD = 1A LOAD = 250mA 80 60 40 LOAD = 100mA LOAD = 10mA 20 0 0.5 1.0 1.5 2.0 2.5 VIN – VOUT (V) Figure 14. 6400 mm2 of PCB Copper, TA = 50°C, LFCSP Rev. 0 | Page 8 of 12 EVAL-ADP1740/ADP1741 LOAD = 2A In cases where the board temperature is known, the thermal characterization parameter, ΨJB, can be used to estimate the junction temperature rise. Maximum junction temperature (TJ) is calculated from the board temperature (TB) and power dissipation (PD) using the following formula: MAX JUNCTION TEMPERATURE 120 LOAD = 500mA LOAD = 1A 100 LOAD = 250mA 80 TJ = TB + (PD × ΨJB) 140 20 2.0 2.5 3.0 VIN – VOUT (V) Figure 15. 500 mm2 of PCB Copper, TA = 50°C, LFCSP 140 LOAD = 1A MAX JUNCTION TEMPERATURE 120 LOAD = 500mA 100 120 LOAD = 2A 100 LOAD = 1A 80 LOAD = 500mA 60 LOAD = 250mA 40 20 0 0.25 80 0.75 1.25 LOAD = 100mA 1.75 2.25 2.75 2.75 VIN – VOUT (V) 60 Figure 17. 500 mm2 of PCB Copper, TB = 25°C, LFCSP LOAD = 10mA 140 1.0 1.5 2.0 2.5 VIN – VOUT (V) Figure 16. 0 mm2 of PCB Copper, TA = 50°C, LFCSP 3.0 07154-039 20 JUNCTION TEMPERATURE, TJ (°C) 40 0 0.5 LOAD = 10mA LOAD = 100mA LOAD = 250mA 07154-040 1.5 MAX JUNCTION TEMPERATURE 07154-041 1.0 JUNCTION TEMPERATURE, TJ (°C) LOAD = 10mA 40 0 0.5 JUNCTION TEMPERATURE, TJ (°C) (4) LOAD = 100mA 60 07154-038 JUNCTION TEMPERATURE, TJ (°C) 140 MAX JUNCTION TEMPERATURE 120 LOAD = 2A LOAD = 1A 100 LOAD = 500mA 80 LOAD = 250mA 60 LOAD = 10mA 40 LOAD = 100mA 20 0 0.25 0.75 1.25 1.75 2.25 VIN – VOUT (V) Figure 18. 500 mm2 of PCB Copper, TB = 50°C, LFCSP Rev. 0 | Page 9 of 12 EVAL-ADP1740/ADP1741 140 JUNCTION TEMPERATURE, TJ (°C) 120 100 LOAD = 2A LOAD = 1A 80 LOAD = 500mA 60 LOAD = 250mA 40 20 LOAD = 100mA 0 0.25 0.75 1.25 1.75 LOAD = 10mA 2.25 VIN – VOUT (V) 2.75 MAX JUNCTION TEMPERATURE 120 LOAD = 1A LOAD = 2A 100 LOAD = 500mA 80 LOAD = 250mA 60 40 LOAD = 100mA LOAD = 10mA 20 0 0.25 0.75 1.25 1.75 2.25 VIN – VOUT (V) Figure 20. 1000 mm2 of PCB Copper, TB = 50°C, LFCSP Figure 19. 1000 mm2 of PCB Copper, TB = 25°C, LFCSP Rev. 0 | Page 10 of 12 2.75 07154-043 MAX JUNCTION TEMPERATURE 07154-042 JUNCTION TEMPERATURE, TJ (°C) 140 EVAL-ADP1740/ADP1741 ORDERING INFORMATION BILL OF MATERIALS Table 4. Components Listing Qty 2 1 3 1 2 1 Reference Designator C1, C2 C3 J1, J2, J3 R3 R1, R2 U1 Description Capacitor, MLCC, 4.7 μF, 6.3 V, 0805, X5R Capacitor, MLCC, 0.01 μF, 50 V, 0603, X5R Header, single, STR, 2 pins Resistor, 100 kΩ, 0.10 W, 0603 Resistor, 0.10 W, 0603 IC, LDO regulator ESD CAUTION ORDERING GUIDE Model ADP1740-1.5-EVALZ1 Output Voltage (V) 1.5 ADP1741-EVALZ1 Adjustable 1 Manufacturer/Vendor Murata or equivalent Murata or equivalent Digi-Key Corp. Vishay or equivalent Vishay or equivalent Analog Devices, Inc. Description Fixed 1.5 V Output Evaluation Board Adjustable Output Evaluation Board Z = RoHS Compliant Part. Rev. 0 | Page 11 of 12 Vendor Part No. GRM219R61A475KE34 GRM188R71H103KA01 S1012E-36-ND CRCW0603100KFKEA Not installed ADP1741ACPZ-R7 ADP1740ACPZ-1.5-R7 EVAL-ADP1740/ADP1741 NOTES ©2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. EB07154-0-11/08(0) Rev. 0 | Page 12 of 12