1 A, Low Dropout, CMOS Linear Regulator ADP1706/ADP1707/ADP1708 TYPICAL APPLICATION CIRCUITS ADP1706 VIN = 5V 1 EN 2 GND 3 IN OUT 6 4 IN OUT 5 SENSE 7 VOUT = 3.3V 4.7µF 4.7µF Figure 1. ADP1706 with Fixed Output Voltage, 3.3 V ADP1707 VIN = 5V 1 EN 2 GND 3 IN OUT 6 4 IN OUT 5 VTRK TRK 8 SENSE 7 VOUT 4.7µF 4.7µF VOUT (V) 3 2 1 0 APPLICATIONS 1 2 3 4 5 VTRK (V) Figure 2. ADP1707 with Output Voltage Tracking ADP1708 VIN = 5V 4.7µF ADJ R2 1 EN 2 GND 3 IN OUT 6 4 IN OUT 5 8 SENSE 7 R1 VOUT = 0.8V(1 + R1/R2) 4.7µF 06640-002 Notebook computers Memory components Telecommunications equipment Network equipment DSP/FPGA/microprocessor supplies Instrumentation equipment/data acquisition systems 10nF SS 8 06640-003 Maximum output current: 1 A Input voltage range: 2.5 V to 5.5 V Low shutdown current: <1 μA Low dropout voltage: 345 mV @ 1 A load Initial accuracy: ±1% Accuracy over line, load, and temperature: ±2.5% 16 fixed output voltage options with soft start: 0.75 V to 3.3 V (ADP1706) 16 fixed output voltage options with tracking 0.75 V to 3.3 V (ADP1707) Adjustable output voltage option: 0.8 V to 5.0 V (ADP1708) Stable with small 4.7 μF ceramic output capacitor Excellent load/line transient response Current limit and thermal overload protection Logic-controlled enable Available in an 8-lead, exposed paddle SOIC and 3 mm × 3 mm, 8-lead exposed paddle LFCSP 06640-001 FEATURES Figure 3. ADP1708 with Adjustable Output Voltage, 0.8 V to 5.0 V GENERAL DESCRIPTION The ADP1706/ADP1707/ADP1708 are CMOS, low dropout linear regulators that operate from 2.5 V to 5.5 V and provide up to 1 A of output current. Using an advanced proprietary architecture, they provide high power supply rejection and achieve excellent line and load transient response with a small 4.7 μF ceramic output capacitor. The ADP1706/ADP1707 are available in 16 fixed output voltage options. The ADP1708 is available in an adjustable version, which allows output voltages that range from 0.8 V to 5.0 V via an external divider. The ADP1706 allows an external soft start capacitor to be connected to program the start-up time; the ADP1707 and ADP1708 contain internal soft start capacitors that give a typical start-up time of 100 μs. The ADP1707 includes a tracking feature that allows the output to follow an external voltage rail or reference. The ADP1706/ADP1707/ADP1708 are available in an 8-lead, exposed paddle SOIC package and an 8-lead, 3 mm × 3 mm exposed paddle LFCSP, making them not only very compact solutions but also providing excellent thermal performance for applications requiring up to 1 A of output current in a small, low profile footprint. Rev. 0 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. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2007 Analog Devices, Inc. All rights reserved. ADP1706/ADP1707/ADP1708 TABLE OF CONTENTS Features .............................................................................................. 1 Soft Start Function (ADP1706) ................................................ 10 Applications....................................................................................... 1 Adjustable Output Voltage (ADP1708)................................... 11 Typical Application Circuits............................................................ 1 Track Mode (ADP1707) ............................................................ 11 General Description ......................................................................... 1 Enable Feature ............................................................................ 11 Revision History ............................................................................... 2 Application Information................................................................ 12 Specifications..................................................................................... 3 Capacitor Selection .................................................................... 12 Absolute Maximum Ratings............................................................ 5 Voltage Tracking Applications.................................................. 12 Thermal Resistance ...................................................................... 5 Current Limit and Thermal Overload Protection ................. 12 ESD Caution.................................................................................. 5 Thermal Considerations............................................................ 13 Pin Configurations and Function Descriptions ........................... 6 PCB Layout Considerations...................................................... 15 Typical Performance Characteristics ............................................. 7 Outline Dimensions ....................................................................... 16 Theory of Operation ...................................................................... 10 Ordering Guide .......................................................................... 17 REVISION HISTORY 6/07—Revision 0: Initial Version Rev. 0 | Page 2 of 20 ADP1706/ADP1707/ADP1708 SPECIFICATIONS VIN = (VOUT + 0.6 V) or 2.5 V (whichever is greater), IOUT = 10 mA, CIN = COUT = 4.7 μF, TA = 25°C, unless otherwise noted. Table 1. Parameter INPUT VOLTAGE RANGE OPERATING SUPPLY CURRENT SHUTDOWN CURRENT OUTPUT VOLTAGE ACCURACY Fixed Output Voltage Accuracy (ADP1706 and ADP1707) Adjustable Output Voltage Accuracy (ADP1708) 1 Symbol VIN IGND IGND-SD VOUT VOUT LINE REGULATION ∆VOUT/∆VIN LOAD REGULATION 2 DROPOUT VOLTAGE 3 ∆VOUT/∆IOUT VDROPOUT Test Conditions TJ = –40°C to +125°C IOUT = 0 mA IOUT = 100 mA IOUT = 100 mA, TJ = −40°C to +125°C IOUT = 1 A IOUT = 1 A, TJ = −40°C to +125°C EN = GND EN = GND, TJ = −40°C to +125°C Min 2.5 IOUT = 10 mA IOUT = 100 μA to 1 A 100 μA < IOUT < 1 A, TJ = −40°C to +125°C IOUT = 10 mA IOUT = 100 μA to 1 A 100 μA < IOUT < 1 A, TJ = −40°C to +125°C VIN = (VOUT + 0.6 V) to 5.5 V, TJ = −40°C to +125°C IOUT = 10 mA to 1 A, TJ = −40°C to +125°C IOUT = 100 mA, VOUT ≥ 3.3 V IOUT = 100 mA, VOUT ≥ 3.3 V, TJ = −40°C to +125°C IOUT = 1 A, VOUT ≥ 3.3 V IOUT = 1 A, VOUT ≥ 3.3 V, TJ = −40°C to +125°C IOUT = 100 mA, 2.5 V ≤ VOUT < 3.3 V IOUT = 100 mA, 2.5 V ≤ VOUT < 3.3 V, TJ = −40°C to +125°C IOUT = 1 A, 2.5 V ≤ VOUT < 3.3 V IOUT = 1 A, 2.5 V ≤ VOUT < 3.3 V, TJ = −40°C to +125°C −1 −1.5 −2.5 0.792 0.788 0.780 −0.1 Max 5.5 1.0 Unit V μA μA μA mA mA μA μA +1 +1.5 +2.5 0.808 0.812 0.820 +0.1 % % % V V V %/ V 0.001 %/mA mV mV 50 310 390 1.2 1.55 0.1 0.8 33 55 345 60 mV mV mV mV 630 mV mV 1.8 μs ms A 1.6 +40 °C °C μA mV +60 mV 0.4 1 100 V V μA nA μA 600 35 365 START-UP TIME 4 ADP1707 and ADP1708 ADP1706 CURRENT LIMIT THRESHOLD 5 THERMAL SHUTDOWN Thermal Shutdown Threshold Thermal Shutdown Hysteresis TSSD TSSD-HYS TJ rising SOFT START SOURCE CURRENT (ADP1706) VOUT to VTRK ACCURACY (ADP1707) SSI-SOURCE VTRK-ERROR SS = GND 0 V ≤ VTRK ≤ (0.5 × VOUT (NOM)), VOUT (NOM) ≤ 1.8 V, TJ = −40°C to +125°C 0 V ≤ VTRK ≤ (0.5 × VOUT (NOM)), VOUT (NOM) > 1.8 V, TJ = −40°C to +125°C 0.6 −40 2.5 V ≤ VIN ≤ 5.5 V 2.5 V ≤ VIN ≤ 5.5 V EN = IN or GND 1.8 EN INPUT EN Input Logic High EN Input Logic Low EN Input Leakage Current ADJ INPUT BIAS CURRENT (ADP1708) SENSE INPUT BIAS CURRENT Typ tSTART-UP CSS = 10 nF ILIMIT VIH VIL VI-LEAKAGE ADJI-BIAS SNSI-BIAS 1.1 Rev. 0 | Page 3 of 20 100 7.3 1.5 150 15 1.1 −60 0.1 30 4 ADP1706/ADP1707/ADP1708 Parameter OUTPUT NOISE Symbol OUTNOISE POWER SUPPLY REJECTION RATIO PSRR Test Conditions 10 Hz to 100 kHz, VOUT = 0.75 V 10 Hz to 100 kHz, VOUT = 3.3 V 1 kHz, VOUT = 0.75 V 1 kHz, VOUT = 3.3 V 1 Min Typ 125 450 70 56 Max Unit μV rms μV rms dB dB Accuracy when OUT is connected directly to ADJ. When OUT voltage is set by external feedback resistors, absolute accuracy in adjust mode depends on the tolerances of resistors used. Based on an end-point calculation using 10 mA and 1 A loads. See Figure 11 for typical load regulation performance for loads less than 10 mA. 3 Dropout voltage is defined as the input-to-output voltage differential when the input voltage is set to the nominal output voltage. This applies only for output voltages above 2.5 V. 4 Start-up time is defined as the time between the rising edge of EN to OUT being at 95% of its nominal value. 5 Current limit threshold is defined as the current at which the output voltage drops to 90% of the specified typical value. For example, the current limit for a 1.0 V output voltage is defined as the current that causes the output voltage to drop to 90% of 1.0 V, or 0.9 V. 2 Rev. 0 | Page 4 of 20 ADP1706/ADP1707/ADP1708 ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Table 2. Parameter IN to GND OUT to GND EN to GND SS/ADJ/TRK to GND SENSE to GND Storage Temperature Range Operating Junction Temperature Range Soldering Conditions Rating −0.3 V to +6 V –0.3 V to IN –0.3 V to +6 V –0.3 V to +6 V –0.3 V to +6 V –65°C to +150°C –40°C to +125°C JEDEC J-STD-020 θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 3. Thermal Resistance Package Type 8-Lead SOIC (Exposed Paddle) 8-Lead 3 mm × 3 mm LFCSP (Exposed Paddle) ESD CAUTION Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Rev. 0 | Page 5 of 20 θJA 58 66 Unit °C/W °C/W ADP1706/ADP1707/ADP1708 SS 7 SENSE 6 OUT 5 OUT IN 3 IN 4 ADP1707 TOP VIEW (Not to Scale) 8 TRK 7 SENSE 6 OUT 5 OUT IN 3 IN 4 ADP1708 TOP VIEW (Not to Scale) 8 ADJ 7 SENSE 6 OUT 5 OUT TOP VIEW (Not to Scale) EN 1 PIN 1 INDICATOR GND 2 ADP1707 IN 3 IN 4 8 SS 7 SENSE 6 OUT 5 OUT TOP VIEW (Not to Scale) 8 TRK 7 SENSE 6 OUT 5 OUT Figure 7. 8-Lead LFCSP, ADP1707 06640-005 EN 1 ADP1706 Figure 5. 8-Lead LFCSP, ADP1706 Figure 6. 8-Lead SOIC, ADP1707 GND 2 GND 2 IN 4 06640-006 EN 1 PIN 1 INDICATOR IN 3 Figure 4. 8-Lead SOIC, ADP1706 GND 2 EN 1 06640-007 IN 4 TOP VIEW (Not to Scale) 8 06640-009 IN 3 ADP1706 EN 1 PIN 1 INDICATOR GND 2 ADP1708 IN 3 IN 4 Figure 8. 8-Lead SOIC, ADP1708 TOP VIEW (Not to Scale) 8 ADJ 7 SENSE 6 OUT 5 OUT 06640-008 EN 1 GND 2 06640-004 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS Figure 9. 8-Lead LFCSP, ADP1708 Table 4. Pin Function Descriptions ADP1706 Pin No. 1 ADP1707 Pin No. 1 ADP1708 Pin No. 1 Mnemonic EN 2 3, 4 5, 6 7 2 3, 4 5, 6 7 2 3, 4 5, 6 7 GND IN OUT SENSE 8 N/A N/A 8 N/A N/A SS TRK N/A EP N/A EP 8 EP ADJ EP Description Enable Input. Drive EN high to turn on the regulator; drive it low to turn off the regulator. For automatic startup, connect EN to IN. Ground. Regulator Input Supply. Bypass IN to GND with a 4.7 μF or greater capacitor. Regulated Output Voltage. Bypass OUT to GND with a 4.7 μF or greater capacitor. Sense. Measures the actual output voltage at the load and feeds it to the error amplifier. Connect SENSE as close as possible to the load to minimize the effect of IR drop between the regulator output and the load. Soft Start. A capacitor connected to this pin determines the soft start time. Track. The output follows the voltage applied at the TRK pin. See the Theory of Operation section for a more detailed description. Adjust. A resistor divider from OUT to ADJ sets the output voltage. The exposed pad on the bottom of the SOIC package and the LFCSP package. EP enhances thermal performance and is electrically connected to GND inside the package. User is recommended to connect EP to the ground plane on the board. Rev. 0 | Page 6 of 20 ADP1706/ADP1707/ADP1708 TYPICAL PERFORMANCE CHARACTERISTICS VIN = 3.8 V, IOUT = 100 mA, CIN = 4.7 μF, COUT = 4.7 μF, TA = 25°C, unless otherwise noted. 1400 3.32 ILOAD = 100µA 3.31 ILOAD = 1A ILOAD = 10mA 1200 3.30 1000 ILOAD = 100mA 3.28 ILOAD = 300mA ILOAD = 500mA 800 600 ILOAD = 300mA 3.27 ILOAD = 500mA 400 ILOAD = 1A 3.26 06640-010 3.25 3.24 –40 10 60 ILOAD = 100mA ILOAD = 10mA 200 0 –40 110 ILOAD = 100µA 10 06640-013 IGND (µA) VOUT (V) 3.29 60 TJ (°C) 110 TJ (°C) Figure 10. Output Voltage vs. Junction Temperature Figure 13. Ground Current vs. Junction Temperature 1400 3.315 3.310 1200 3.305 1000 IGND (µA) VOUT (V) 3.300 3.295 3.290 800 600 3.285 400 3.280 1 10 100 06640-014 3.270 0.1 200 06640-011 3.275 0 0.1 1000 1 10 ILOAD (mA) Figure 11. Output Voltage vs. Load Current 2100 ILOAD = 100µA 1800 ILOAD = 10mA ILOAD = 100mA ILOAD = 1A ILOAD = 500mA ILOAD = 300mA 1500 ILOAD = 100mA IGND (µA) ILOAD = 300mA ILOAD = 500mA 3.28 1200 ILOAD = 10mA ILOAD = 100µA 900 600 3.26 300 3.25 3.8 4.2 4.6 5.0 0 3.6 5.4 06640-015 ILOAD = 1A 3.27 06640-012 VOUT (V) 3.30 3.29 1000 Figure 14. Ground Current vs. Load Current 3.32 3.31 100 ILOAD (mA) 4.0 4.4 4.8 5.2 VIN (V) VIN (V) Figure 12. Output Voltage vs. Input Voltage Figure 15. Ground Current vs. Input Voltage Rev. 0 | Page 7 of 20 ADP1706/ADP1707/ADP1708 400 350 LOAD SWITCHED FROM 50mA TO 950mA AND BACK TO 50mA 250 50mV/DIV VDROPOUT (mV) 300 200 150 VOUT VIN = 3.8V VOUT = 1.6V CIN = 4.7µF COUT = 4.7µF 06640-017 50 0 10 1000 100 06640-020 100 TIME (20µs/DIV) ILOAD (mA) Figure 19. Load Transient Response, CIN = 4.7 μF, COUT = 4.7 μF Figure 16. Dropout Voltage vs. Load Current 3.4 3.3 LOAD SWITCHED FROM 50mA TO 950mA AND BACK TO 50mA 3.2 2.9 2.8 ILOAD ILOAD ILOAD ILOAD ILOAD ILOAD 2.7 2.6 2.5 3.0 3.2 3.4 3.6 = 10mA = 100mA = 300mA = 500mA = 750mA = 1A 3.8 VOUT VIN = 3.8V VOUT = 1.6V CIN = 22μF COUT = 22μF 4.0 06640-021 50mV/DIV 3.0 06640-018 VOUT (V) 3.1 TIME (20μs/DIV) VIN (V) Figure 17. Output Voltage vs. Input Voltage (in Dropout) 2500 2V/DIV ILOAD = 1A ILOAD = 750mA ILOAD = 500mA ILOAD = 300mA ILOAD = 100mA ILOAD = 10mA 2000 VIN STEP FROM 4V TO 5V 1000 VOUT 500 0 3.0 VOUT = 3.3V CIN = 4.7μF COUT = 4.7μF ILOAD = 1A 3.2 3.4 3.6 3.8 4.0 TIME (100μs/DIV) VIN (V) Figure 18. Ground Current vs. Input Voltage (in Dropout) Figure 21. Line Transient Response Rev. 0 | Page 8 of 20 06640-022 20mV/DIV 1500 06640-019 IGND (µA) Figure 20. Load Transient Response, CIN = 22 μF, COUT = 22 μF ADP1706/ADP1707/ADP1708 –40 18 VRIPPLE = 50mV ILOAD = 10mA COUT = 4.7μF FREQUENCY = 10kHz 16 VOUT = 2.4V –45 12 PSRR (dB) RAMP-UP TIME (ms) 14 10 8 6 VOUT = 1.6V –50 4 0 5 10 15 20 –55 2.7 25 3.2 3.7 Figure 22. Output Voltage Ramp-Up Time vs. Soft Start Capacitor Value –10 –20 VRIPPLE = 50mV VIN = 5V VOUT = 3.3V COUT = 4.7μF –35 –40 PSRR (dB) PSRR (dB) Figure 25. ADP1708 Power Supply Rejection Ratio vs. Input Voltage ILOAD = 300mA ILOAD = 200mA ILOAD = 100mA ILOAD = 10mA ILOAD = 1mA ILOAD = 100µA –30 4.7 VIN (V) CSS (nF) 0 4.2 06640-026 0 VOUT = 0.8V 06640-023 2 –40 –50 VRIPPLE = 50mV VIN = 5V ILOAD = 10mA COUT = 4.7μF FREQUENCY = 10kHz –45 –60 –90 10 06640-024 –80 100 1k 10k 100k 1M –55 0.8 10M Figure 23. ADP1706 Power Supply Rejection Ratio vs. Frequency –10 –20 VRIPPLE = 50mV VIN = 5V VOUT = 0.8V COUT = 4.7μF PSRR (dB) –40 –50 –60 –70 06640-025 –80 –90 10 100 1k 10k 100k 1.8 2.3 2.8 3.3 3.8 4.3 Figure 26. ADP1708 Power Supply Rejection Ratio vs. Output Voltage ILOAD = 300mA ILOAD = 200mA ILOAD = 100mA ILOAD = 10mA ILOAD = 1mA ILOAD = 100µA –30 1.3 VOUT (V) FREQUENCY (Hz) 0 06640-027 –50 –70 1M 10M FREQUENCY (Hz) Figure 24. ADP1708 Power Supply Rejection Ratio vs. Frequency Rev. 0 | Page 9 of 20 ADP1706/ADP1707/ADP1708 THEORY OF OPERATION The ADP1706/ADP1707/ADP1708 are low dropout linear regulators that use an advanced, proprietary architecture to provide high power supply rejection ratio (PSRR) and excellent line and load transient response with a small 4.7 μF ceramic output capacitor. All devices operate from a 2.5 V to 5.5 V input rail and provide up to 1 A of output current. Supply current in shutdown mode is typically 100 nA. IN providing a smooth ramp-up to the nominal output voltage. The soft start time is calculated by TSS = VREF × (CSS/ISS) (1) where: TSS is the soft start period. VREF is the 0.8 V reference voltage. CSS is the soft start capacitance from SS to GND. ISS is the current sourced from SS (1.2 μA). When the ADP1706 is disabled (using EN), the soft start capacitor is discharged to GND through an internal 100 Ω resistor. OUT SENSE CURRENT LIMIT THERMAL PROTECT EN SHUTDOWN The ADP1706/ADP1707 are available in 16 fixed output voltage options between 0.75 V and 3.3 V. The ADP1706 allows for connection of an external soft start capacitor, which controls the output voltage ramp during startup. The ADP1707 features a TRK pin that allows the output voltage to follow the voltage at this pin. The ADP1708 is available in an adjustable version with an output voltage that can be set to between 0.8 V and 5.0 V by an external voltage divider. All devices are controlled by an enable pin (EN). VIN = 5V VOUT = 3.3V COUT = 4.7μF CSS = 10nF ILOAD = 1A 1 TIME (2ms/DIV) Figure 28. OUT Ramp-Up with External Soft Start Capacitor The ADP1707 and ADP1708 have no pins for soft start; therefore, the function is switched to an internal soft start capacitor, which sets the soft start ramp-up period to approximately 48 μs. Note that the ramp-up period is the time it takes OUT to go from 0% to 90% of the nominal value and is different from the start-up time in Table 1, which is the time between the rising edge of EN to OUT being at 90% of the nominal value. For the worst-case output voltage of 5 V, using the suggested 4.7 μF output capacitor, the resulting input inrush current is approximately 490 mA, which is less than the maximum 1 A load current. SOFT START FUNCTION (ADP1706) For applications that require a controlled startup, the ADP1706 provides a programmable soft start function. The programmable soft start is useful for reducing inrush current upon startup and for providing voltage sequencing. To implement a soft start, connect a small ceramic capacitor from SS to GND. Upon startup, a 1.2 μA current source charges this capacitor. The ADP1706 start-up output voltage is limited by the voltage at SS, Rev. 0 | Page 10 of 20 EN 2 1 VIN = 5V VOUT = 1.6V COUT = 4.7μF ILOAD = 10mA OUT TIME (20µs/DIV) Figure 29. OUT Ramp-Up with Internal Soft Start 06640-029 Internally, the ADP1706/ADP1707/ADP1708 consist of a reference, an error amplifier, a feedback voltage divider, and a PMOS pass transistor. Output current is delivered via the PMOS pass device, which is controlled by the error amplifier. The error amplifier compares the reference voltage with the feedback voltage from the output and amplifies the difference. If the feedback voltage is lower than the reference voltage, the gate of the PMOS device is pulled lower, allowing more current to pass and increasing the output voltage. If the feedback voltage is higher than the reference voltage, the gate of the PMOS device is pulled higher, allowing less current to pass and decreasing the output voltage. 1V/DIV Figure 27. Internal Block Diagram 06640-028 2V/DIV OUT 2V/DIV GND 2 1V/DIV SOFT START REFERENCE 06640-016 EN ADJ/ TRK/ SS ADP1706/ADP1707/ADP1708 ADJUSTABLE OUTPUT VOLTAGE (ADP1708) ENABLE FEATURE The ADP1708 can have its output voltage set over a 0.8 V to 5.0 V range. The output voltage is set by connecting a resistive voltage divider from OUT to ADJ. The output voltage is calculated by The ADP1706/ADP1707/ADP1708 use the EN pin to enable and disable the OUT pin under normal operating conditions. As shown in Figure 31, when a rising voltage on EN crosses the active threshold, OUT turns on. When a falling voltage on EN crosses the inactive threshold, OUT turns off. VOUT = 0.8 V (1 + R1/R2) (2) where: R1 is the resistor from OUT to ADJ. R2 is the resistor from ADJ to GND. EN 500mV/DIV The maximum bias current into ADJ is 100 nA, so for less than 0.5% error due to the bias current, use values less than 60 kΩ for R2. TRACK MODE (ADP1707) VIN = 5V VOUT = 1.6V COUT = 4.7μF ILOAD = 10mA TIME (10ms/DIV) 4.0 Figure 31. ADP1706 Typical EN Pin Operation 3.5 As shown in Figure 31, the EN pin has hysteresis built in. This prevents on/off oscillations that can occur due to noise on the EN pin as it passes through the threshold points. 3.0 The EN pin active/inactive thresholds are derived from the IN voltage. Therefore, these thresholds vary when changing the input voltage. Figure 32 shows typical EN active/inactive thresholds when the input voltage varies from 2.5 V to 5.5 V. 2.0 1.5 1.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 1.3 5.0 VTRK (V) Figure 30. ADP1707 Output Voltage vs. Tracking Voltage For example, consider an ADP1707 with a nominal output voltage of 3.3 V. If the voltage applied to its TRK pin is greater than 3.3 V, OUT maintains a nominal output voltage of 3.3 V. If the voltage applied to TRK is reduced below 3.3 V, OUT tracks this voltage. OUT can track the TRK pin voltage from the nominal value all the way down to 0 V. A voltage divider is present from TRK to the error amplifier input with a divider ratio equal to the divider from OUT to the error amplifier, which sets the output voltage equal to the tracking voltage. Both divider ratios are set by postpackage trim, depending on the desired output voltage. Rev. 0 | Page 11 of 20 1.2 1.1 EN ACTIVE HYSTERESIS 1.0 0.9 0.8 0.7 EN INACTIVE 0.6 06640-032 0 1.4 06640-030 VIN = 3.8V VOUT = 3.3V ILOAD = 10mA 0.5 TYPICAL EN THRESHOLDS (V) VOUT (V) 2.5 0 06640-031 OUT The ADP1707 includes a tracking mode feature. As shown in Figure 30, if the voltage applied at the TRK pin is less than the nominal output voltage, OUT is equal to the voltage at TRK. Otherwise, OUT regulates to its nominal output value. 0.5 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 VIN (V) Figure 32. Typical EN Pin Thresholds vs. Input Voltage ADP1706/ADP1707/ADP1708 APPLICATION INFORMATION CAPACITOR SELECTION Input Bypass Capacitor Output Capacitor Connecting a 4.7 μF capacitor from the IN pin to GND reduces the circuit sensitivity to the printed circuit board (PCB) layout, especially when long input traces, or high source impedance, is encountered. If greater than 4.7 μF of output capacitance is required, it is recommended that the input capacitor be increased to match it. VOUT RESPONSE TO LOAD STEP FROM 50mA TO 950mA Input and Output Capacitor Properties Any good quality ceramic capacitors can be used with the ADP1706/ADP1707/ADP1708, as long as they meet the minimum capacitance and maximum ESR requirements. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior over temperature and applied voltage. Capacitors must have a dielectric adequate to ensure the minimum capacitance over the necessary temperature range and dc bias conditions. X5R or X7R dielectrics with a voltage rating of 6.3 V or 10 V are recommended. Y5V and Z5U dielectrics are not recommended, due to their poor temperature and dc bias characteristics. VOLTAGE TRACKING APPLICATIONS RATIO VOLTAGE TRACKING ADP1706-2.5 VIN = 3.8V VOUT = 1.6V CIN = 4.7μF COUT = 4.7μF 06640-033 5V IN OUT EN SS R1 GND 2.5V 2.5V 1.2V ADP1707-1.2 TIME (2μs/DIV) RATIO TRACKING VOUT R2 OUT TRK IN EN GND Figure 33. Output Transient Response, COUT = 4.7 μF I/O POWER RAIL CORE RAIL 1.2V TIME 06640-042 50mV/DIV The ADP1706/ADP1707/ADP1708 are designed for operation with small, space-saving ceramic capacitors, but they function with most commonly used capacitors as long as care is taken with the effective series resistance (ESR) value. The ESR of the output capacitor affects stability of the LDO control loop. A minimum of 4.7 μF capacitance with an ESR of 500 mΩ or less is recommended to ensure stability of the ADP1706/ADP1707/ADP1708. Transient response to changes in load current is also affected by output capacitance. Using a larger value of output capacitance improves the transient response of the ADP1706/ADP1707/ADP1708 to large changes in load current. Figure 33 and Figure 34 show the transient responses for output capacitance values of 4.7 μF and 22 μF, respectively. Figure 35 shows an application where the ADP1707 tracking feature is used. An ADP1706 powers the I/O of a microprocessor and an ADP1707 powers the core. At startup, the output of the ADP1706 ramps to 2.5 V, which is divided down via a voltage divider (R1 and R2) to a lower voltage at the TRK pin of the ADP1707. The output of the ADP1707 thus follows the TRK pin and ramps up steadily to 1.2 V. This implementation ensures that the core of the processor powers up after the I/O. VOUT RESPONSE TO LOAD STEP FROM 50mA TO 950mA VIN = 3.8V VOUT = 1.6V CIN = 22μF COUT = 22μF TIME (2μs/DIV) Figure 34. Output Transient Response, COUT = 22 μF 06640-034 50mV/DIV Figure 35. Voltage Tracking Feature Using ADP1707 CURRENT LIMIT AND THERMAL OVERLOAD PROTECTION The ADP1706/ADP1707/ADP1708 are protected against damage due to excessive power dissipation by current and thermal overload protection circuits. The ADP1706/ADP1707/ ADP1708 are designed to reach current limit when the output load reaches 1.5 A (typical). When the output load exceeds 1.5 A, the output voltage is reduced to maintain a constant current limit. Rev. 0 | Page 12 of 20 ADP1706/ADP1707/ADP1708 Thermal overload protection is included, which limits the junction temperature to a maximum of 150°C (typical). Under extreme conditions (that is, high ambient temperature and power dissipation) when the junction temperature starts to rise above 150°C, the output is turned off, reducing the output current to zero. When the junction temperature drops below 135°C (typical), the output is turned on again and output current is restored to its nominal value. Consider the case where a hard short from OUT to ground occurs. At first, the ADP1706/ADP1707/ADP1708 reach current limit so that only 1.5 A is conducted into the short. If self-heating of the junction becomes great enough to cause its temperature to rise above 150°C, thermal shutdown activates, turning off the output and reducing the output current to zero. As the junction temperature cools and drops below 135°C, the output turns on and conducts 1.5 A into the short, again causing the junction temperature to rise above 150°C. This thermal oscillation between 135°C and 150°C causes a current oscillation between 1.5 A and 0 A that continues as long as the short remains at the output. Current and thermal limit protections are intended to protect the device against accidental overload conditions. For reliable operation, device power dissipation should be externally limited so junction temperatures do not exceed 125°C. The junction temperature of the ADP1706/ADP1707/ADP1708 can be calculated by TJ = TA + (PD × θJA) where: TA is the ambient temperature. PD is the power dissipation in the die, given by PD = [(VIN – VOUT) × ILOAD] + (VIN × IGND) Power dissipation due to ground current is quite small and can be ignored. Therefore, the junction temperature equation simplifies to the following: TJ = TA + {[(VIN – VOUT) × ILOAD] × θJA} 140 MAX TJ (DO NOT OPERATE ABOVE THIS POINT) Table 5. Typical θJA Values 1 (5) As shown in Equation 5, for a given ambient temperature, input-to-output voltage differential, and continuous load current, a minimum copper size requirement exists for the PCB to ensure the junction temperature does not rise above 125°C. Figure 36 to Figure 41 show junction temperature calculations for different ambient temperatures, load currents, VIN to VOUT differentials, and areas of PCB copper. 120 100 80 60 40 20 1mA 10mA 0 0.5 1.0 100mA 300mA 1.5 2.0 500mA 750mA 2.5 3.0 1A (LOAD CURRENT) 3.5 4.0 4.5 VIN – VOUT (V) θJA (°C/W), LFCSP 65.9 62.3 61.2 59.7 59.4 Device soldered to minimum size pin traces. Rev. 0 | Page 13 of 20 Figure 36. 500 mm2 of PCB Copper, TA = 25°C, SOIC 06640-035 TJ (°C) To guarantee reliable operation, the junction temperature of the ADP1706/ADP1707/ADP1708 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 5 shows typical θJA values of the 8-lead SOIC and 8-lead LFCSP for various PCB copper sizes. θJA (°C/W), SOIC 57.6 53.1 52.3 51.3 51.3 (4) where: ILOAD is the load current. IGND is the ground current. VIN and VOUT are the input and output voltages, respectively. THERMAL CONSIDERATIONS Copper Size (mm2) 01 50 100 300 500 (3) 5.0 ADP1706/ADP1707/ADP1708 140 140 MAX TJ (DO NOT OPERATE ABOVE THIS POINT) 120 120 100 100 80 80 TJ (°C) 60 40 0 0.5 1mA 10mA 1.0 100mA 300mA 1.5 2.0 500mA 750mA 2.5 3.0 1A (LOAD CURRENT) 3.5 4.0 4.5 20 06640-036 20 0 0.5 5.0 1mA 10mA 1.0 100mA 300mA 1.5 2.0 VIN – VOUT (V) 3.0 3.5 4.0 5.0 4.5 Figure 40. 100 mm2 of PCB Copper, TA = 25°C, LFCSP 140 140 MAX TJ (DO NOT OPERATE ABOVE THIS POINT) MAX TJ (DO NOT OPERATE ABOVE THIS POINT) 120 120 100 100 80 80 TJ (°C) TJ (°C) 2.5 1A (LOAD CURRENT) VIN – VOUT (V) Figure 37. 100 mm2 of PCB Copper, TA = 25°C, SOIC 60 40 60 40 0 0.5 1mA 10mA 1.0 100mA 300mA 1.5 2.0 500mA 750mA 2.5 3.0 1A (LOAD CURRENT) 3.5 4.0 4.5 20 06640-037 20 0 0.5 5.0 VIN – VOUT (V) MAX TJ (DO NOT OPERATE ABOVE THIS POINT) 120 100 80 60 20 1.0 100mA 300mA 1.5 2.0 500mA 750mA 2.5 3.0 1A (LOAD CURRENT) 3.5 4.0 4.5 06640-038 40 1mA 10mA 1.0 100mA 300mA 1.5 2.0 500mA 750mA 2.5 3.0 1A (LOAD CURRENT) 3.5 4.0 4.5 Figure 41. 0 mm2 of PCB Copper, TA = 25°C, LFCSP 140 0 0.5 1mA 10mA VIN – VOUT (V) Figure 38. 0 mm2 of PCB Copper, TA = 25°C, SOIC TJ (°C) 500mA 750mA 06640-039 40 60 5.0 VIN – VOUT (V) Figure 39. 500 mm2 of PCB Copper, TA = 25°C, LFCSP Rev. 0 | Page 14 of 20 06640-040 TJ (°C) MAX TJ (DO NOT OPERATE ABOVE THIS POINT) 5.0 ADP1706/ADP1707/ADP1708 PCB LAYOUT CONSIDERATIONS Heat dissipation from the package can be improved by increasing the amount of copper attached to the pins of the ADP1706/ADP1707/ADP1708. However, as can be seen from Table 5, a point of diminishing returns is eventually reached, beyond which an increase in the copper size does not yield significant heat dissipation benefits. Use of 0402 or 0603 size capacitors and resistors achieves the smallest possible footprint solution on boards where area is limited. The ADP1706/ADP1707/ADP1708 feature an exposed pad on the bottom of both the SOIC and LFCSP packages to improve thermal performance. Because the exposed pad is electrically connected to GND inside the package, it is recommended that it also be connected to the ground plane on the PCB with a sufficient amount of copper. ANALOG DEVICES ADP1706/ADP1707/ADP1708 SOIC8 GND C3 C1 U1 • • R1 R2 Place the input capacitor as close as possible to the IN and GND pins. Place the output capacitor as close as possible to the OUT and GND pins. For the ADP1706, place the soft start capacitor as close as possible to the SS pin. Connect the load as close as possible to the OUT and SENSE pins. Rev. 0 | Page 15 of 20 VIN GND VOUT EN ADJ/TRK/SS Figure 42. Example PCB Layout GND 06640-041 • GND J1 Here are a few general tips when designing PCBs: • C2 ADP1706/ADP1707/ADP1708 OUTLINE DIMENSIONS 5.00 (0.197) 4.90 (0.193) 4.80 (0.189) 4.00 (0.157) 3.90 (0.154) 3.80 (0.150) 8 5 TOP VIEW 1 4 3.098 (0.122) 2.41 (0.095) 6.20 (0.244) 6.00 (0.236) 5.80 (0.228) BOTTOM VIEW 1.27 (0.05) BSC (PINS UP) 1.75 (0.069) 1.35 (0.053) 1.65 (0.065) 1.25 (0.049) 0.10 (0.004) MAX COPLANARITY 0.10 SEATING PLANE 0.51 (0.020) 0.31 (0.012) 0.50 (0.020) 0.25 (0.010) 0.25 (0.0098) 0.17 (0.0067) 45° 1.27 (0.050) 0.40 (0.016) 8° 0° COMPLIANT TO JEDEC STANDARDS MS-012-A A 060506-A CONTROLLING DIMENSIONS ARE IN MILLIMETER; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure 43. 8-Lead Standard Small Outline Package, with Expose Pad [SOIC_N_EP] Narrow Body (RD-8-2) Dimensions shown in millimeters and (inches) 3.25 3.00 SQ 2.75 0.60 MAX 5 TOP VIEW PIN 1 INDICATOR 2.95 2.75 SQ 2.55 8 12° MAX 1 1.89 1.74 1.59 PIN 1 INDICATOR 0.05 MAX 0.01 NOM 0.30 0.23 0.18 0.20 REF Figure 44. 8-Lead Frame Chip Scale Package [LFCSP_VD] 3 mm × 3 mm Body, Very Thin, Dual Lead (CP-8-2) Dimensions shown in millimeters Rev. 0 | Page 16 of 20 061507-B SEATING PLANE 0.50 0.40 0.30 0.70 MAX 0.65 TYP 1.60 1.45 1.30 EXPOSED PAD (BOTTOM VIEW) 4 0.90 MAX 0.85 NOM 0.50 BSC 0.60 MAX ADP1706/ADP1707/ADP1708 ORDERING GUIDE Model ADP1706ARDZ-0.75R7 1 ADP1706ARDZ-0.8-R71 ADP1706ARDZ-0.85R71 ADP1706ARDZ-0.9-R71 ADP1706ARDZ-0.95R71 ADP1706ARDZ-1.0-R71 ADP1706ARDZ-1.05R71 ADP1706ARDZ-1.1-R71 ADP1706ARDZ-1.15R71 ADP1706ARDZ-1.2-R71 ADP1706ARDZ-1.3-R71 ADP1706ARDZ-1.5-R71 ADP1706ARDZ-1.8-R71 ADP1706ARDZ-2.5-R71 ADP1706ARDZ-3.0-R71 ADP1706ARDZ-3.3-R71 ADP1706ACPZ-0.75R71 ADP1706ACPZ-0.8-R71 ADP1706ACPZ-0.85R71 ADP1706ACPZ-0.9-R71 ADP1706ACPZ-0.95R71 ADP1706ACPZ-1.0-R71 ADP1706ACPZ-1.05R71 ADP1706ACPZ-1.1-R71 ADP1706ACPZ-1.15R71 ADP1706ACPZ-1.2-R71 ADP1706ACPZ-1.3-R71 ADP1706ACPZ-1.5-R71 ADP1706ACPZ-1.8-R71 ADP1706ACPZ-2.5-R71 ADP1706ACPZ-3.0-R71 ADP1706ACPZ-3.3-R71 ADP1707ARDZ-0.75R71 ADP1707ARDZ-0.8-R71 ADP1707ARDZ-0.85R71 ADP1707ARDZ-0.9-R71 ADP1707ARDZ-0.95R71 ADP1707ARDZ-1.0-R71 ADP1707ARDZ-1.05R71 ADP1707ARDZ-1.1-R71 ADP1707ARDZ-1.15R71 ADP1707ARDZ-1.2-R71 ADP1707ARDZ-1.3-R71 ADP1707ARDZ-1.5-R71 ADP1707ARDZ-1.8-R71 ADP1707ARDZ-2.5-R71 ADP1707ARDZ-3.0-R71 ADP1707ARDZ-3.3-R71 Temperature Range –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C Output Voltage (V) 0.75 0.8 0.85 0.9 0.95 1.0 1.05 1.1 1.15 1.2 1.3 1.5 1.8 2.5 3.0 3.3 0.75 0.8 0.85 0.9 0.95 1.0 1.05 1.1 1.15 1.2 1.3 1.5 1.8 2.5 3.0 3.3 0.75 0.8 0.85 0.9 0.95 1.0 1.05 1.1 1.15 1.2 1.3 1.5 1.8 2.5 3.0 3.3 Rev. 0 | Page 17 of 20 Package Description 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP Package Option RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 RD-8-2 Branding L62 L63 L64 L6J L68 L65 L67 L66 L69 L6A L6C L6D L6H L6E L6F L6G ADP1706/ADP1707/ADP1708 Model ADP1707ACPZ-0.75R71 ADP1707ACPZ-0.8-R71 ADP1707ACPZ-0.85R71 ADP1707ACPZ-0.9-R71 ADP1707ACPZ-0.95R71 ADP1707ACPZ-1.0-R71 ADP1707ACPZ-1.05R71 ADP1707ACPZ-1.1-R71 ADP1707ACPZ-1.15R71 ADP1707ACPZ-1.2-R71 ADP1707ACPZ-1.3-R71 ADP1707ACPZ-1.5-R71 ADP1707ACPZ-1.8-R71 ADP1707ACPZ-2.5-R71 ADP1707ACPZ-3.0-R71 ADP1707ACPZ-3.3-R71 ADP1708ARDZ-R71 ADP1708ACPZ-R71 ADP1706-3.3-EVALZ1 ADP1707-3.3-EVALZ1 ADP1708-EVALZ1 1 Temperature Range –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C Output Voltage (V) 0.75 0.8 0.85 0.9 0.95 1.0 1.05 1.1 1.15 1.2 1.3 1.5 1.8 2.5 3.0 3.3 0.8 to 5.0 0.8 to 5.0 3.3 3.3 Adjustable, but set to 1.6 V Z = RoHS Compliant Part. Rev. 0 | Page 18 of 20 Package Description 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead LFCSP_VD 8-Lead SOIC_N_EP 8-Lead LFCSP_VD Evaluation Board Evaluation Board Evaluation Board Package Option CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 CP-8-2 RD-8-2 CP-8-2 Branding L6P L6Q L6R L6S L6T L6U L6V L6W L6X L6Y L6Z L70 L71 L72 L73 L74 L7P ADP1706/ADP1707/ADP1708 NOTES Rev. 0 | Page 19 of 20 ADP1706/ADP1707/ADP1708 NOTES ©2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06640-0-6/07(0) Rev. 0 | Page 20 of 20