ADP3302

a FEATURES High Accuracy: 0.8% Ultralow Dropout Voltage: 120 mV @ 100 mA Typical Requires only CO = 0.47 F for Stability anyCAP™ = Stable with All Types of Capacitors Current and Thermal Limiting Low Noise Dropout Detector Multiple Voltage Options Thermally Enhanced SO-8 Package APPLICATIONS Cellular Telephones Notebook and Palmtop Computers Battery Powered Systems Portable Instruments High Efficiency Linear Regulators High Precision anyCAP™ Dual Low Dropout Linear Regulator ADP3302 FUNCTIONAL BLOCK DIAGRAM (1/2 IS SHOWN) ADP3302 OUT CC R1 IN THERMAL PROTECTION Q2 SD BANDGAP REF GND DRIVER Q1 ERR GM R2 EOUT 2 GENERAL DESCRIPTION 330kΩ VOUT1 0.47µF The ADP3302 is a member of the ADP330X family of precision micropower low dropout anyCAP™ regulators. The ADP3302 contains two fully independent 100 mA regulators with separate shutdown and merged error outputs. It features 1.4% overall output accuracy and very low, 120 mV typical, dropout voltage. The ADP3302 has a wide input voltage range from 3 V to 12 V. It features an error flag that signals when either of the two regulators is about to lose regulation. It has short circuit current protection as well as thermal shutdown. The ADP3302’s enhanced lead frame design allows for a maximum power dissipation of 630 mW @ +70°C ambient temperature and 1.0 W at room temperature without any external heat sink. anyCAP™ is a trademark of Analog Devices, Inc. VIN 0.47µF ERR 5 8 IN IN OUT1 1 ADP3302 3 GND OUT2 4 SD2 6 VOUT2 0.47µF SD1 7 ON OFF Figure 1. Application Circuit R EV. 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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 617/329-4700 World Wide Web Site: http://www.analog.com Fax: 617/326-8703 © Analog Devices, Inc., 1997 ADP3302–SPECIFICATIONS noted) Parameter GROUND CURRENT GROUND CURRENT IN DROPOUT DROPOUT VOLTAGE Symbol IGND IGND VDROP (@ TA = –20 C to +85 C, VIN = 7 V, CIN = 0.47 F, COUT = 0.47 F, unless otherwise 1 Conditions IL1 = IL2 = 100 mA IL1 = IL2 = 0.1 mA VIN = 2.5 V IL1 = IL2 = 0.1 mA VOUT ≤ 98% of VO, Nominal IL = 100 mA IL = 10 mA IL = 1 m A ON OFF 0 < VSD < 5 V 5 ≤ VSD ≤ 12 V, @ VIN = 12 V VSDI = VSD2 = 0, TA = +25°C, @ VIN =12 V VSDI = VSD2 = 0, TA = +85°C, @ VIN =12 V TA = +85°C, @ VIN = 12 V TA = +25°C, @ VIN = 12 V VEO = 5 V ISINK = 400 µA VIN = Nominal VOUT +1 V VIN = 12 V, IL = 100 mA T = 10 ms f = 10 Hz–100 kHz, @ TA = +25°C VOUT = 3.3 V VOUT = 5 V Min Typ 2 0.4 1.0 Max 4 0.8 2 Units mA mA mA 0.12 0.05 0.02 2.0 0.9 0.9 0 0.2 0.1 0.05 0.3 1 22 1 5 12 2 13 V V V V V µA µA µA µA µA µA µA V mA %/W SHUTDOWN THRESHOLD SHUTDOWN PIN INPUT CURRENT GROUND CURRENT IN SHUTDOWN MODE VTHSD ISDIN IQ 0 OUTPUT CURRENT IN SHUTDOWN MODE ERROR PIN OUTPUT LEAKAGE ERROR PIN OUTPUT “LOW” VOLTAGE PEAK LOAD CURRENT THERMAL REGULATION OUTPUT NOISE IOSD IEL VEOL ILDPK ∆ VO VO 0.15 200 0.05 0.3 VNOISE 75 110 µV rms µV rms NOTES 1 Ambient temperature of 85°C corresponds to a typical junction temperature of +125°C. Specifications subject to change without notice. ADP3302-3.0–SPECIFICATIONS (@ T = –20 C to +85 C, V = 3.3 V, C = 0.47 otherwise noted) A IN IN F, COUT = 0.47 F, unless Typ 3 Max 3.024 Units V Parameter OUTPUT VOLTAGE Symbol VOUT1 or VOUT2 Conditions VIN = 3.3 V to 12 V IL = 0.1 mA to 100 mA TA= +25°C VIN = 3.3 V to 12 V IL = 0.1 mA to 100 mA VIN = 3.3 V to 12 V TA = +25°C, IL = 0.1 mA IL = 0.1 mA to 100 mA TA = +25°C IL = 0.1 mA to 100 mA TA = +25°C Min 2.976 2.958 3 0.024 0.030 1 3.042 V mV/V mV/mA µV/mA LINE REGULATION LOAD REGULATION CROSS REGULATION ∆ VO ∆ V IN ∆ VO ∆I L ∆ V 01 ∆I L2 ∆ V 02 or ∆I L1 Specifications subject to change without notice. – 2– REV. 0 ADP3302 ADP3302-3.2–SPECIFICATIONS Parameter OUTPUT VOLTAGE Symbol VOUT1 or VOUT2 (@ TA = –20 C to +85 C, VIN = 3.5 V, CIN = 0.47 F, COUT = 0.47 F, unless otherwise noted) Min 3.174 Typ 3.2 Max 3.226 Units V Conditions VIN = 3.5 V to 12 V IL = 0.1 mA to 100 mA TA= +25°C VIN = 3.5 V to 12 V IL = 0.1 mA to 100 mA VIN = 3.5 V to 12 V TA = +25°C, IL = 0.1 mA IL = 0.1 mA to 100 mA TA = +25°C IL = 0.1 mA to 100 mA TA = +25°C 3.155 3.2 0.026 0.032 1 3.245 V mV/V mV/mA µV/mA LINE REGULATION LOAD REGULATION CROSS REGULATION ∆ VO ∆ V IN ∆ VO ∆I L ∆ V 01 ∆I L2 or Specifications subject to change without notice. ∆ V 02 ∆I L1 ADP3302-3.3–SPECIFICATIONS (@ T = –20 C to +85 C, V = 3.6 V, C = 0.47 otherwise noted) A IN IN F, COUT = 0.47 F, unless Typ 3.3 Max 3.327 Units V Parameter OUTPUT VOLTAGE Symbol VOUT1 or VOUT2 Conditions VIN = 3.6 V to 12 V IL = 0.1 mA to 100 mA TA= +25°C VIN = 3.6 V to 12 V IL = 0.1 mA to 100 mA VIN = 3.6 V to 12 V TA = +25°C, IL = 0.1 mA IL = 0.1 mA to 100 mA TA = +25°C IL = 0.1 mA to 100 mA TA = +25°C Min 3.273 3.253 3.3 0.026 0.033 1 3.347 V mV/V mV/mA µV/mA LINE REGULATION LOAD REGULATION CROSS REGULATION ∆ VO ∆ V IN ∆ VO ∆I L ∆ V 01 ∆I L2 ∆ V 02 or ∆I L1 Specifications subject to change without notice. ADP3302-5.0–SPECIFICATIONS (@ T = –20 C to +85 C, V = 5.3 V, C = 0.47 otherwise noted) A IN IN F, COUT = 0.47 F, unless Typ 5.0 Max 5.040 Units V Parameter OUTPUT VOLTAGE Symbol VOUT1 or VOUT2 Conditions VIN = 5.3 V to 12 V IL = 0.1 mA to 100 mA TA= +25°C VIN = 5.3 V to 12 V IL = 0.1 mA to 100 mA VIN = 5.3 V to 12 V TA = +25°C, IL = 0.1 mA IL = 0.1 mA to 100 mA TA = +25°C IL = 0.1 mA to 100 mA TA = +25°C Min 4.960 4.930 5.0 0.04 0.05 1 5.070 V mV/V mV/mA µV/mA LINE REGULATION LOAD REGULATION CROSS REGULATION ∆ VO ∆ V IN ∆ VO ∆I L ∆ V 01 ∆I L2 or ∆ V 02 ∆I L1 Specifications subject to change without notice. REV. 0 – 3– ADP3302 ABSOLUTE MAXIMUM RATINGS* PIN FUNCTION DESCRIPTIONS Input Supply Voltage . . . . . . . . . . . . . . . . . . . . –0.3 V to +16 V Please note: Pins 5 and 8 should be connected externally for proper operation. Shutdown Input Voltage . . . . . . . . . . . . . . . . . –0.3 V to +16 V Error Flag Output Voltage . . . . . . . . . . . . . . . . –0.3 V to +16 V Power Dissipation . . . . . . . . . . . . . . . . . . . . Internally Limited Operating Ambient Temperature Range . . . . –55°C to +125°C Operating Junction Temperature Range . . . . –55°C to +125°C θJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96°C/W θJC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55°C/W Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C Lead Temperature Range (Soldering 10 sec) . . . . . . . . +300°C Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215°C Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C *This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operation section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Pin 1 Name OUT1 Function Output of Regulator 1, fixed 3.0 V, 3.2 V, 3.3 V or 5 V output voltage. Sources up to 200 mA. Bypass to ground with a 0.47 µF capacitor. Open Collector Output. Active low indicates that one of the two outputs is about to go out of regulation. Ground Pin. Output Regulator 2. Independent of Regulator 1. Fixed 3.0 V, 3.2 V, 3.3 V or 5 V output voltage. Bypass to ground with a 0.47 F capacitor. Regulator Input. Supply voltage can range from 3.0 V to 12 V. Pins 5 and 8 must be connected together for proper operation. Active Low Shutdown Pin for Regulator 2. Connect to ground to disable the Out 2 output. When shutdown is not used, this pin should be connected to the input pin. Shutdown Pin for Regulator 1, otherwise identical to SD2. PIN CONFIGURATION 2 ERR 3 4 GND OUT2 5, 8 IN ORDERING GUIDE 6 Package Option* SD2 Model ADP3302AR1 ADP3302AR2 ADP3302AR3 ADP3302AR4 ADP3302AR5 Voltage Outputs OUT 1 OUT 2 OUT 1 OUT 2 OUT 1 OUT 2 OUT 1 OUT 2 OUT 1 OUT 2 3.0 V 3.0 V 3.2 V 3.2 V 3.3 V 3.3 V 3.3 V 5.0 V 5.0 V 5.0 V SO-8 SO-8 SO-8 SO-8 SO-8 SO-8 SO-8 SO-8 SO-8 SO-8 7 SD1 OUT 1 1 ERR 2 8 IN ADP3302 7 SD1 TOP VIEW GND 3 (Not to Scale) 6 SD2 OUT 2 4 5 IN NOTES *SO = Small Outline Package. Contact factory for availability of customized options available with mixed output voltages. CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the ADP3302 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. WARNING! ESD SENSITIVE DEVICE – 4– REV. 0 Typical Performance Characteristics– ADP3302 5.001 IL = 0mA 5 OUTPUT VOLTAGE – Volts OUTPUT VOLTAGE – Volts 5.005 1.6 1.4 GROUND CURRENT – mA IL = 1mA 4.999 IL = 20mA 5.000 VIN = 7V 4.995 IL = IL2 =0 1.2 1.0 0.8 0.6 0.4 0.2 4.998 4.990 4.997 IL = 100mA 4.996 4.985 4.995 8 10 12 5.1 5.2 5.3 5.4 5.5 6 INPUT VOLTAGE – Volts 14 16 4.980 0.0 0 25 50 75 100 125 150 175 OUTPUT LOAD – mA 200 1 3 5 7 9 11 INPUT VOLTAGE – Volts 13 16 Figure 2. Line Regulation Output Voltage vs. Supply Voltage on ADP3302AR5 Figure 3. Output Voltage vs. Load Current Up to 200 mA on ADP3302AR5 Figure 4. Quiescent Current vs. Supply Voltage–ADP3302AR3 5 VIN = 7V GROUND CURRENT – mA 0.2 3000 IL1 = 0 TO 200mA IL2 = 0 TO 200mA 3 GROUND CURRENT – µA OUTPUT VOLTAGE – % 4 0.1 2500 IL1 = 100mA IL2 = 100mA 0.0 IL = 0 –0.1 2000 1500 2 –0.2 1000 IL1 = 100mA IL2 = 0mA 1 IL1 = 0 TO 200mA IL2 = 0mA 0 0 50 100 150 OUTPUT LOAD – mA 200 –0.3 500 IL1 = 0mA IL2 = 0mA –0.4 –45 –25 –5 15 35 55 75 95 115 135 TEMPERATURE – °C 0 –45 –25 –5 15 35 55 75 95 115 135 TEMPERATURE – °C Figure 5. Quiescent Current vs. Load Current Figure 6. Output Voltage Variation % vs. Temperature Figure 7. Quiescent Current vs. Temperature 250 5 8.0 VIN INPUT/OUTPUT VOLTAGE – Volts INPUT-OUTPUT VOLTAGE – mV 200 4 INPUT/OUTPUT VOLTAGE – Volts 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0 0 20 40 60 VSD = VIN CL = 0.47µF RL = 33Ω 80 100 120 140 160 180 200 TIME – µs VOUT 150 3 100 2 RL = 33Ω 1 50 0 0 20 40 60 80 100 120 140 160 180 200 OUTPUT LOAD – mA 0 0 1 2 4 3 2 3 INPUT VOLTAGE – Volts 1 0 Figure 8. Dropout Voltage vs. Output Current Figure 9. Power-Up/Power-Down on ADP3302AR3. SD = 3 V or VIN Figure 10. Power-Up Transient on ADP3302AR1 REV. 0 – 5– ADP3302 –Typical Performance Characteristics 3.31 3.3 3.3kΩ, 0.47µF LOAD 3.29 3.31 3.3 33Ω, 0.47µF LOAD 3.29 7.5 VIN 7 0 40 80 120 160 200 240 280 320 360 400 TIME – µs 3.29 7.5 mA VIN 7 0 40 80 120 160 200 240 280 320 360 400 TIME – µs 3.29 3.31 3.31 3.3 3.3kΩ, 10µF LOAD 3.305 Volts 3.3 VOUT1 CL = 0.47µF 3.295 Volts Volts 5.002 Volts 3.3 33Ω, 10µF LOAD VOUT2 5 4.998 I (VOUT1) 100mA 100 0 0 200 400 600 TIME – µs 800 1000 Figure 11. Line Transient Response— (0.47 µ F Load) on ADP3302AR4 Figure 12. Line Transient Response (10 µ F Load) on ADP3302AR4 Figure 13. Load Transient on VOUT1 and Crosstalk of VOUT2 on ADP3302AR4 for 1 mA to 100 mA Pulse 5 3.302 Volts Volts 3.3 CL = 10µF 5.03 5.01 VOUT1 3.5 0 400 3.3V Volts 4 3 CL = 0.47µF RL = 33Ω 3.298 3.3V 2 CL = 4.7µF 1 0 Volts 5 4.99 4.97 VOUT2 mA 300 200 Volts 100 5 0 3V 0 20 40 60 80 100 120 140 160 180 200 TIME – µs mA 100 0 0 200 I (VOUT2) 100mA 0 400 600 TIME – µs 800 1000 0 1 2 3 TIME – sec 4 5 Figure 14. Load Transient on VOUT2 and Crosstalk on VOUT1 on ADP3302AR4 for 1 mA to 100 mA Pulse Figure 15. Short Circuit Current Figure 16. Turn On ADP3302AR3 VOLTAGE NOISE SPECTRAL DENSITY – µV/ Hz 4 C = 0.47µF R = 33Ω ON 3.3V OUTPUT 3 RIPPLE REJECTION – dB 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 ac 100 1k 10k 100k FREQUENCY – Hz 1M 10M bd c a d a. 0.47µF @ NO LOAD b. 0.47µF @ 33Ω c. 10µF @ NO LOAD d. 10µF @ 33Ω 0.8 c a 0.6 0.47µF BYPASS PIN 5, 8 TO PIN 3 b 2 Volts VOUT 1 0 0.4 bd b 0.2 a. 0.47µF @ NO LOAD b. 0.47µF @ 33Ω c. 10µF @ NO LOAD d. 10µF @ 33Ω 103 104 FREQUENCY = Hz d a c 105 5 VSD 0 0 5 10 15 20 25 30 35 40 45 TIME – µs 50 –100 10 0 102 Figure 17. Turn Off on ADP3302AR3 Figure 18. Power Supply Ripple Rejection on ADP3302AR3 Figure 19. Output Noise Density on ADP3302AR5 – 6– REV. 0 ADP3302 APPLICATION INFORMATION anyCAP™ To limit the maximum junction temperature to 125°C, maximum ambient temperature must be lower than: TAMAX = 125°C 43.6°C = 81.4°C The ADP3302 is an easy to use dual low dropout voltage regulator. The ADP3302 requires only a very small 0.47 µF bypass capacitor on the outputs for stability. Unlike the conventional LDO designs, the ADP3302 is stable with virtually any type of capacitors (anyCAP™) independent of the capacitor’s ESR (Effective Series Resistance) value. Capacitor Selection PRINTED CIRCUIT BOARD LAYOUT CONSIDERATION All surface mount packages rely on the traces of the PC board to conduct heat away from the package. In standard packages the dominant component of the heat resistance path is the plastic between the die attach pad and the individual leads. In typical thermally enhanced packages one or more of the leads are fused to the die attach pad, significantly decreasing this component. However, to make the improvement meaningful, a significant copper area on the PCB has to be attached to these fused pins. The ADP3302’s patented thermal coastline lead frame design uniformly minimizes the value of the dominant portion of the thermal resistance. It ensures that heat is conducted away by all pins of the package. This yields a very low 96°C/W thermal resistance for an SO-8 package, without any special board layout requirements, relying just on the normal traces connected to the leads. The thermal resistance can be decreased by, approximately, an additional 10% by attaching a few square cm of copper area to the two VIN pins of the ADP3302 package. It is not recommended to use solder mask or silkscreen on the PCB traces adjacent to the ADP3302 pins since it will increase the junction to ambient thermal resistance of the package. Shutdown Mode Output Capacitors: As with any micropower device, output transient response is a function of the output capacitance. The ADP3302 is stable with a wide range of capacitor values, types and ESR (anyCAP™). A capacitor as low as 0.47 F is all that is needed for stability. However, larger capacitors can be used if high output current surges are anticipated. The ADP3302 is stable with extremely low ESR capacitors (ESR ≈ 0), such as multilayer ceramic capacitors (MLCC) or OSCON. Input Bypass Capacitor: An input bypass capacitor is not required. However, for applications where the input source is high impedance or far from the input pins, a bypass capacitor is recommended. Connecting a 0.47 F capacitor from the input pins (Pins 5 and 8) to ground reduces the circuit’s sensitivity to PC board layout. Low ESR capacitors offer better performance on a noisy supply; however, for less demanding requirements a standard tantalum or aluminum electrolytic capacitor is adequate. Thermal Overload Protection The ADP3302 is protected against damage due to excessive power dissipation by its thermal overload protection circuit, which limits the die temperature to a maximum of 165°C. Under extreme conditions (i.e., high ambient temperature and power dissipation) where die temperature starts to rise above 165°C, the output current is reduced until the die temperature has dropped to a safe level. The output current is restored when the die temperature is reduced. Current and thermal limit protections are intended to protect the device against accidental overload conditions. For normal operation, device power dissipation should be externally limited so that junction temperatures will not exceed 125°C. Calculating Junction Temperature Applying a TTL high signal to the shutdown pin or tying it to the input pin will turn the output ON. Pulling the shutdown pin down to a TTL low signal or tying it to ground will turn the output OFF. Outputs are independently controlled. In shutdown mode, quiescent current is reduced to less than 2 A. Error Flag Dropout Detector The ADP3302 will maintain its output voltage over a wide range of load, input voltage and temperature conditions. If regulation is lost, for example, by reducing the supply voltage below the combined regulated output and dropout voltages, the ERRor flag will be activated. The ERR output is an open collector, which will be driven low. Once set, the ERRor flag’s hysteresis will keep the output low until a small margin of operating range is restored, either by raising the supply voltage or reducing the load. A single ERR pin serves both regulators in the ADP3302 and indicates that one or both regulators are on the verge of losing regulation. APPLICATION CIRCUIT Dual Post Regulator Circuit for Switching Regulators Device power dissipation is calculated as follows: PD = (VIN – VOUT1) ILOAD1 + (VIN – VOUT2) ILOAD2 + (VIN) IGND Where ILOAD1 and ILOAD2 are Load currents on Outputs 1 and 2, IGND is ground current, VIN and VOUT are input and output voltages respectively. Assuming ILOAD1 = ILOAD2 = 100 mA, IGND = 2 mA, VIN = 7.2 V and VOUT1 = VOUT2 = 5.0 V, device power dissipation is: PD = (7.2 V – 5 V) 100 mA + (7.2 V – 5 V) 100 mA + (7.2 V) 2 mA = 0.454 W The proprietary thermal coastline lead frame used in the ADP3302 yields a thermal resistance of 96°C/W, which is significantly lower than a standard 8-pin SOIC package at 170°C/W. Junction temperature above ambient temperature will be approximately equal to: 0.454 W 96°C/W = 43.6°C The ADP3302 can be used to implement a dual 3 V/100 mA post regulator power supply from a 1 cell Li-Ion input (Figure 20). This circuit takes 2.5 V to 4.2 V as the input and delivers dual 3 V/100 mA outputs. Figure 21 shows the typical efficiency curve. For ease of explanation, let’s partition the circuit into the ADP3000 step-up regulator section and the ADP3302 low dropout regulation section. Furthermore, let’s divide the operation of this application circuit into the following three phases. REV. 0 – 7– ADP3302 2.5V → 4.2V R1 100kΩ C1 100µF 10V AVX-TPS R3 1MΩ R2 90kΩ R4 120kΩ ILIM SET VIN SW1 R5 330kΩ Q1 2N2907 R8 10kΩ R7 90kΩ R9 348kΩ 1% R10 200kΩ 1% (SUMIDA–CDRH62) L1 6.6µF IN5817 IN C3 100µF 10V AVX-TPS IN VO2 1µF 6V C4 (MLC) 1µF C5 6V (MLC) 3V 100mA R6 100kΩ C2 33nF ADP3000 AO GND SW2 FB ADP3302 SD GND VO2 3V 100mA Figure 20. Cell Li-Ion to 3 V/200 mA Converter with Shutdown at VIN < 2.5 V Phase One: When the input voltage is equal to 3.7 V or higher, the ADP3000 is off and the ADP3302 operates on its own to regulate the output voltage. At this phase, current is flowing into the input pins of the ADP3302 via the inductor L1 and the Schottky diode. At the same time, the ADP3000 is set into sleep mode by pulling the FB pin (via R9 and R10 resistor divider network) to about 10% higher than its internal reference which is set to be 1.245 V. Phase Two: As the input voltage drops below 3.7 V, the decreasing input voltage causes the voltage of the FB pin to be within 5% of the 1.245 V reference. This triggers the ADP3000 to turn on, providing a 3.4 V regulated output to the inputs of the ADP3302. The ADP3000 continues to supply the 3.4 V regulated voltage to the ADP3302 until the input voltage drops below 2.5 V. Phase Three: When the input voltage drops below 2.5 V, the ADP3302 will shut down and the ADP3000 will go into sleep mode. With the input voltage below 2.5 V, the resistor divider network, R1 and R2, applies a voltage that is lower than the ADP3000’s internal 1.245 V reference voltage to the SET pin. This causes the AO pin to have a voltage close to 0 V, which causes the ADP3302 to go into shutdown directly and Q1 to turn on and pull the FB pin 10% or higher than the internal 1.245 V reference voltage. With the FB pin pulled high, the ADP3000 goes into sleep mode. 80 IO = 50mA + 50mA AT VIN ≤ 2.5V SHDN IQ = 500µA Supply Sequencing Circuit Figure 22 shows a simple and effective way to achieve sequencing of two different output voltages, 3.3 V and 5 V, in a mixed supply voltage system. In most cases, these systems need careful sequencing for the supplies to avoid latchup. At turn-on, D1 rapidly charges up C1 and enables the 5 V output. After a R2-C2 time constant delay, the 3.3 V output is enabled. At turn-off, D2 quickly discharges C2 and R3 pulls SD1 low, turning off the 3.3 V output first. After a R1-C1 time constant delay, the 5 V output turns off. VIN = 6V TO 12V 8 2 C5 1µF D2 C2 0.01µF D1 C1 0.01µF R1 220kΩ IN IN SD1 ERR OUT1 1 C3 0.5µF VOUT1 3.3V 5 D3 7 3.3V ON/OFF R3 330kΩ 6 ADP3302 OUT2 4 SD2 GND 3 C4 0.5µF VOUT2 5.0V R2 220kΩ Figure 22. Turn-On/Turn-Off Sequencing for Mixed Supply Voltages OUTLINE DIMENSIONS Dimensions shown in inches and (mm). % EFFICIENCY 75 8-Pin SOIC (SO-8) IO = 100mA + 100mA 70 65 2.6 3.0 0.1968 (5.00) 0.1890 (4.80) 8 1 5 4 3.4 3.8 4.2 VIN (V) 0.1574 (4.00) 0.1497 (3.80) 0.2440 (6.20) 0.2284 (5.80) Figure 21. Typical Efficiency of the Circuit of Figure 20 PIN 1 0.0098 (0.25) 0.0040 (0.10) Refer to Figure 20. R9 and R10 set the output voltage of the ADP3000. R1, R2, and R3 set the shutdown threshold voltage for the circuit. For further details on the ADP3000, please refer to the ADP3000 data sheet. 0.0688 (1.75) 0.0532 (1.35) 0.0196 (0.50) x 45° 0.0099 (0.25) SEATING PLANE 0.0500 0.0192 (0.49) (1.27) 0.0138 (0.35) BSC 0.0098 (0.25) 0.0075 (0.19) 8° 0° 0.0500 (1.27) 0.0160 (0.41) – 8– REV. 0 PRINTED IN U.S.A. C2989-12-1/97