ADP3000

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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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. a ADP3000 Tel: 617/329-4700 World Wide Web Site: http://www.analog.com Fax: 617/326-8703 © Analog Devices, Inc., 1997 Micropower Step-Up/Step-Down Fixed 3.3 V, 5 V, 12 V and Adjustable High Frequency Switching Regulator FUNCTIONAL BLOCK DIAGRAM COMPARATOR GAIN BLOCK/ ERROR AMP 400kHz OSCILLATOR DRIVER 1.245V REFERENCE R1 R2 ADP3000 SET VIN GND SENSE ILIM SW1 SW2

FEATURES

Operates at Supply Voltages from 2 V to 30 V Works in Step-Up or Step-Down Mode Very Few External Components Required High Frequency Operation Up to 400 kHz Low Battery Detector on Chip User Adjustable Current Limit Fixed and Adjustable Output Voltage 8-Pin DIP and SO-8 Package Small Inductors and Capacitors

APPLICATIONS

Notebook, Palmtop Computers Cellular Telephones Hard Disk Drives Portable Instruments Pagers GENERAL DESCRIPTION The ADP3000 is a versatile step-up/step-down switching regulator that operates from an input supply voltage of 2 V to 12 V in step-up mode and up to 30 V in step-down mode. The ADP3000 operates in Pulse Frequency Mode (PFM) and consumes only 500 µA, making it highly suitable for applica- tions that require low quiescent current. The ADP3000 can deliver an output current of 100 mA at

3 V from a 5 V input in step-down configuration and 180 mA at

3.3 V from a 2 V input in step-up configuration. The auxiliary gain amplifier can be used as a low battery detector, linear regulator undervoltage lockout or error amplifier. The ADP3000 operates at 400 kHz switching frequency. This allows the use of small external components (inductors and capacitors), making the device very suitable for space constrained designs. ADP3000-3.3V 1 2 ILIM VIN SW1 FB (SENSE) SW2GND 100µF 10V 120Ω 6.8µH IN5817 100µF 10V V IN 2V–3.2V 3.3V @ 180mA C1, C2: AVX TPS D107 M010R0100 L1: SUMIDA CD43-6R8 Figure 1. Typical Application Figure 2. Step-Down Mode Operation

–2– REV. 0 ADP3000–SPECIFICATIONS ADP3000 Parameter Conditions Symbol Min Typ Max Units INPUT VOLTAGE Step-Up Mode V IN 2.0 12.6 V Step-Down Mode 30.0 V SHUTDOWN QUIESCENT CURRENT V FB > 1.43 V; VSENSE > 1.1 × VOUT IQ 500 µA COMPARATOR TRIP POINT ADP3000 1 1.20 1.245 1.30 V VOLTAGE OUTPUT SENSE VOLTAGE ADP3000-3.3 2 3.135 3.3 3.465 V ADP3000-52 VOUT 4.75 5.00 5.25 V ADP3000-122 11.40 12.00 12.60 V COMPARATOR HYSTERESIS ADP3000 8 12.5 mV OUTPUT HYSTERESIS ADP3000-3.3 32 50 mV ADP3000-5 32 50 mV ADP3000-12 75 120 mV OSCILLATOR FREQUENCY f OSC 350 400 450 kHz DUTY CYCLE V FB > VREF D6 5 8 0 % SWITCH ON TIME I LIM Tied to VIN, VFB = 0 t ON 1.5 2 2.55 µs SWITCH SATURATION VOLTAGE T A = +25°C STEP-UP MODE V IN = 3.0 V, ISW = 650 mA V SAT 0.5 0.75 V VIN = 5.0 V, ISW = 1 A 0.8 1.1 V STEP-DOWN MODE V IN = 12 V, ISW = 650 mA 1.1 1.5 V FEEDBACK PIN BIAS CURRENT ADP3000 V FB = 0 V I FB 160 330 nA SET PIN BIAS CURRENT V SET = VREF ISET 200 400 nA GAIN BLOCK OUTPUT LOW I SINK = 300 µAV OL 0.15 0.4 V VSET = 1.00 V REFERENCE LINE REGULATION 5 V ≤ VIN ≤ 30 V 0.02 0.15 %/V 2 V ≤ VIN ≤ 5 V 0.2 0.6 %/V GAIN BLOCK GAIN R L = 100 kΩ 3 AV 1000 6000 V/V GAIN BLOCK CURRENT SINK V SET ≤ 1 V I SINK 300 µA CURRENT LIMIT 220 Ω from ILIM to VIN ILIM 400 mA CURRENT LIMIT TEMPERATURE COEFFICIENT –0.3 %/ °C SWITCH OFF LEAKAGE CURRENT Measured at SW1 Pin 1 10 µA VSW1 = 12 V, TA = +25°C MAXIMUM EXCURSION BELOW GND T A = +25°C ISW1 ≤ 10 µA, Switch Off –400 –350 mV NOTES 1This specification guarantees that both the high and low trip point of the comparator fall within the 1.20 V to 1.30 V range. 2The output voltage waveform will exhibit a sawtooth shape due to the comparator hysteresis. The output voltage on the fixed output versions will always be within the specified range. 3100 kΩ resistor connected between a 5 V source and the AO pin. *All limits at temperature extremes are guaranteed via correlation using standard statistical methods. Specifications subject to change without notice. (08C ≤ TA ≤ +708C, VIN = 3 V unless otherwise noted)*

–3–REV. 0 PIN DESCRIPTIONS Mnemonic Function ILIM For normal conditions this pin is connected to VIN. When lower current is required, a resistor should be connected between I LIM and VIN. Limiting the switch current to 400 mA is achieved by connecting a 220 Ω resistor. V IN Input Voltage. SW1 Collector of power transistor. For step-down configuration, connect to V IN. For step-up configuration, connect to an inductor/diode. SW2 Emitter of power transistor. For step-down configuration, connect to inductor/diode. For step-up configuration, connect to ground. Do not allow this pin to go more than a diode drop below ground. GND Ground. AO Auxiliary Gain (GB) output. The open col- lector can sink 300 µA. It can be left open if not used. SET SET Gain amplifier input. The amplifier’s positive input is connected to SET pin and its negative input is connected to 1.245 V. It can be left open if not used. FB/SENSE On the ADP3000 (adjustable) version, this pin is connected to the comparator input. On the ADP3000-3.3, ADP3000-5 and ADP3000-12, the pin goes directly to the internal resistor divider that sets the output voltage. WARNING! ESD SENSITIVE DEVICE 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 ADP3000 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. ABSOLUTE MAXIMUM RATINGS Thermal Impedance PIN CONFIGURATIONS 8-Lead Plastic DIP 8-Lead SOIC (N-8) (SO-8) TOP VIEW (Not to Scale) ADP3000 ILIM VIN SW1 SW2 FB (SENSE)* SET AO GND * FIXED VERSIONS TOP VIEW (Not to Scale) ADP3000 ILIM VIN SW1 SW2 FB (SENSE)* SET AO GND * FIXED VERSIONS ORDERING GUIDE Output Package Model Voltage Option ADP3000AN-3.3 3.3 V N-8 ADP3000AR-3.3 3.3 V SO-8 ADP3000AN-5 5 V N-8 ADP3000AR-5 5 V SO-8 ADP3000AN-12 12 V N-8 ADP3000AR-12 12 V SO-8 ADP3000AN Adjustable N-8 ADP3000AR Adjustable SO-8 N = plastic DIP, SO = small outline package. Figure 3a. Fu nctional Block Diagram for Adjustable Version Figure 3b. Functional Block Diagram for Fixed Version COMPARATOR GAIN BLOCK/ ERROR AMP OSCILLATOR DRIVER 1.245V REFERENCE ADP3000 SET VIN GND FB ILIM SW1 SW2 COMPARATOR GAIN BLOCK/ ERROR AMP OSCILLATOR DRIVER 1.245V REFERENCE R1 R2 ADP3000 SET VIN GND SENSE ILIM SW1 SW2

–6– REV. 0 THEORY OF OPERATION The ADP3000 is a versatile, high frequency, switch mode power supply (SMPS) controller. The regulated output voltage can be greater than the input voltage (boost or step-up mode) or less than the input (buck or step-down mode). This device uses a gated oscillator technique to provide high perfor- mance with low quiescent current. A functional block diagram of the ADP3000 is shown in Figure 3a. The internal 1.245 V reference is connected to one input of the comparator, while the other input is externally connected (via the FB pin) to a resistor divider connected to the regulated output. When the voltage at the FB pin falls below 1.245 V, the 400 kHz oscillator turns on. A driver amplifier provides base drive to the internal power switch and the switching action raises the output voltage. When the voltage at the FB pin exceeds 1.245 V, the oscillator is shut off. While the oscillator is off, the ADP3000 quiescent current is only 500 µA. The comparator’s hysteresis ensures loop stability without requiring external components for frequency compensation. The maximum current in the internal power switch can be set by connecting a resistor between V IN and the ILIM pin. When the maximum current is exceeded, the switch is turned OFF. The current limit circuitry has a time delay of about 0.3 µs. If an external resistor is not used, connect I LIM to VIN. This yields the maximum feasible current limit. Further information on I LIM is included in the “Applications” section of this data sheet. The ADP3000 internal oscillator provides typically 1.7 µs ON and 0.8 µs OFF times. An uncommitted gain block on the ADP3000 can be con- nected as a low battery detector. The inverting input of the gain block is internally connected to the 1.245 V reference. The noninverting input is available at the SET pin. A resistor divider, connected between V IN and GND with the junction connected to the SET pin, causes the AO output to go LOW when the low battery set point is exceeded. The AO output is an open collector NPN transistor that can sink in excess of 300 µA. The ADP3000 provides external connections for both the collector and emitter of its internal power switch, which permits both step-up and step-down modes of operation. For the step- up mode, the emitter (Pin SW2) is connected to GND and the collector (Pin SW1) drives the inductor. For step-down mode, the emitter drives the inductor while the collector is connected to V IN. The output voltage of the ADP3000 is set with two external resistors. Three fixed voltage models are also available: ADP3000–3.3 (+3.3 V), ADP3000–5 (+5 V) and ADP3000–12 (+12 V). The fixed voltage models include laser-trimmed voltage-setting resistors on the chip. On the fixed voltage models of the ADP3000, simply connect the feedback pin (Pin 8) directly to the output voltage. APPLICATIONS INFORMATION COMPONENT SELECTION Inductor Selection For most applications the inductor used with the ADP3000 will fall in the range between 4.7 µH to 33 µH. Table I shows recommended inductors and their vendors. When selecting an inductor, it is very important to make sure that the inductor used with the ADP3000 is able to handle a current that is higher than the ADP3000’s current limit without saturation. As a rule of thumb, powdered iron cores saturate softly, whereas Ferrite cores saturate abruptly. Rod or “open” drum core geometry inductors saturate gradually. Inductors that saturate gradually are easier to use. Even though rod or drum core inductors are attractive in both price and physical size, these types of inductors must be handled with care because they have high magnetic radiation. Toroid or “closed” core geometry should be used when minimizing EMI is critical. In addition, inductor dc resistance causes power loss. It is best to use low dc resistance inductors so that power loss in the inductor is kept to the minimum. Typically, it is best to use an inductor with a dc resistance lower than 0.2 Ω . Table I. Recommended Inductors Vendor Series Core Type Phone Numbers Coiltronics OCTAPAC Toroid (407) 241-7876 Coiltronics UNIPAC Open (407) 241-7876 Sumida CD43, CD54 Open (847) 956-0666 Sumida CDRH62, CDRH73, Semi-Closed (847) 956-0666 CDRH64 Geometry Capacitor Selection For most applications, the capacitor used with the ADP3000 will fall in the range between 33 µF to 220 µF. Table II shows recommended capacitors and their vendors. For input and output capacitors, use low ESR type capacitors for best efficiency and lowest ripple. Recommended capacitors include AVX TPS series, Sprague 595D series, Panasonic HFQ series and Sanyo OS-CON series. When selecting a capacitor, it is important to make sure the maximum capacitor ripple current rms rating is higher than the ADP3000’s rms switching current. It is best to protect the input capacitor from high turn-on cur- rent charging surges by derating the capacitor voltage by 2:1. For very low input or output voltage ripple requirements, Sanyo OS-CON series capacitors can be used since this type of capacitor has very low ESR. Alternatively, two or more tanta- lum capacitors can be used in parallel.

resistor, and RHYS creates the hysteresis. 19 shows the proper way to place the protection diode, D2. ing diode (see Diode Selection section for information). Figure 19. Step-Down Model V OUT > 6.0 V with the following equations. current limit not programmed externally. IQ = 500 µA (Typical Shutdown Quiescent Current). current limit is not programmed eternally. VCE(SAT) = Check this value by applying ISW to Figure 8b. IQ = 500 µA (Typical Shutdown Quiescent Current). β = 30 (Typical Forced Beta). PD = Device Power Dissipation. θJA = Thermal Resistance (Junction-to-Ambient). ISW = 0.8 A (Externally Programmed). junction temperature of 125 °C.

–11–REV. 0 8-Lead Plastic DIP 8-Lead SOIC (N-8) (SO-8) 0.430 (10.92) 0.348 (8.84) 0.280 (7.11) 0.240 (6.10) PIN 1 SEATING PLANE0.022 (0.558) 0.014 (0.356) 0.060 (1.52) 0.015 (0.38) 0.210 (5.33) MAX 0.130 (3.30) MIN 0.070 (1.77) 0.045 (1.15) 0.100 (2.54) BSC 0.160 (4.06) 0.115 (2.93) 0.325 (8.25) 0.300 (7.62) 0.015 (0.381) 0.008 (0.204) 0.195 (4.95) 0.115 (2.93) 0.1968 (5.00) 0.1890 (4.80) 8 5 0.2440 (6.20) 0.2284 (5.80) PIN 1 0.1574 (4.00) 0.1497 (3.80) 0.0688 (1.75) 0.0532 (1.35)SEATING PLANE 0.0098 (0.25) 0.0040 (0.10) 0.0192 (0.49) 0.0138 (0.35) 0.0500 (1.27) BSC 0.0098 (0.25) 0.0075 (0.19) 0.0500 (1.27) 0.0160 (0.41) 0.0196 (0.50) 0.0099 (0.25)x 45° OUTLINE DIMENSIONS Dimensions shown in inches and (mm).

–12– C2223–12–1/97PRINTED IN U.S.A.