ADP3330ART-3

a FEATURES High Accuracy Over Line and Load: 0.7% @ +25 C, 1.4% Over Temperature Ultralow Dropout Voltage: 140 mV (Typ) @ 200 mA Requires Only CO = 0.47 F for Stability anyCAP = Stable with Any Type of Capacitor (Including MLCC) Current and Thermal Limiting Low Noise Low Shutdown Current: 230°C/W for a standard SOT-23 leadframe. Figure 22 shows the difference between the standard SOT-23 and the Chip-on-Lead leadframes. –8– REV. A ADP3330 Printed Circuit Board Layout Considerations Low Power, Low Dropout Applications 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. To make the improvement meaningful, however, a significant copper area on the PCB must be attached to these fused pins. The patented chip-on-lead frame design of the ADP3330 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 165°C/W thermal resistance for an SOT-23-6 package, without any special board layout requirements, just relying on the normal traces connected to the leads. This yields a 17% improvement in heat dissipation capability as compared to a standard SOT-23-6 package. The thermal resistance can be decreased by, approximately, an additional 10% by attaching a few square cm of copper area to the VIN pin of the ADP3303 package. It is not recommended to use solder mask or silkscreen on the PCB traces adjacent to the ADP3330’s pins since it will increase the junction to ambient thermal resistance of the package. Error Flag Dropout Detector ADP3330 is well suited for applications such as cellular phone handsets that require low quiescent current and low dropout voltage features. ADP3330 draws 34 µA typical under light load situations (i.e., load current = 100 µA), which results in low power consumption when the cell phone is in standby mode. Figure 23 shows an application in which the ADP3330 is used in a handset to provide 2.75 V nominal output voltage. The cell phone is powered from 3 cell NiCd or 1 cell Li-Ion battery. ADP3330 guarantees an accuracy of 1.4%, even when the input/ output differential is merely 250 mV (worst case). This implies that the output is regulated and within specification even when the battery voltage has reached its end-of-discharge voltage of 3 V. The output voltage never falls below 2.7 V, even under worst case load and temperature conditions. The low dropout feature coupled with the high accuracy of the ADP3330 ensures that the system is reliably powered until the end of the life of the battery, which results in increased system talk time. END OF DISCHARGE VOLTAGE OF 3 CELL NiCd OR 1 CELL Li-Ion BATTERY MINIMUM BATTERY VOLTAGE 3.0V 250mV MAXIMUM INPUT-OUTPUT OVERHEAD FOR 200mA OUTPUT CURRENT NOMINAL OUTPUT VOLTAGE 2.75V –1.4% OUTPUT VOLTAGE ACCURACY 2.712V ABSOLUTE MINIMUM OUTPUT VOLTAGE 2.700V 12mV TRANSIENT, LINE AND LOAD RESPECTIVE MARGIN The ADP3330 will maintain its output voltage over a wide range of load, input voltage and temperature conditions. If the output is about to lose regulation by reducing the supply voltage below the combined regulated output and dropout voltages, the ERR flag will be activated. The ERR output is an open collector, which will be driven low. Once set, the ERR 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. Shutdown Mode Figure 23. LDO Budgeting for a 3 Cell NiCd/1 Cell Li-Ion Supply Applying a TTL high signal to the shutdown (SD) pin, or tying it to the input pin, will turn the output ON. Pulling SD down to 0.4 V or below, or tying it to ground, will turn the output OFF. In shutdown mode, quiescent current is reduced to much less than 1 µA. REV. A –9– ADP3330 APPLICATION CIRCUITS Crossover Switch Higher Output Current The circuit in Figure 24 shows how two ADP3330s can be used to form a mixed supply voltage system. The output switches between two different levels selected by an external digital input. Output voltages can be any combination of voltages from the Ordering Guide of the data sheet. VIN = 3.85V TO 12V IN OUT VOUT = 3.6V/2.5V The ADP3330 can source up to 200 mA at room temperature without any heatsink or pass transistor. If higher current is needed, an appropriate pass transistor can be used, as in Figure 25, to increase the output current to 1 A. VIN = 4.5V TO 8V C1 100 F R1 50 MJE253* VOUT = 3V@1A OUTPUT SELECT 3V 0V ADP3330-3.6 SD GND IN OUT + C2 100 F ADP3330-3 SD GND ERR C1+ 1.0 F LOGIC SUPPLY IN OUT + ADP3330-2.5 SD GND C2 0.47 F *AAVID531002 HEAT SINK IS USED Figure 25. High Output Current Linear Regulator Figure 24. Crossover Switch –10– REV. A ADP3330 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 6-Lead Surface Mount RT-6 (SOT-23-6) 0.122 (3.10) 0.106 (2.70) 0.071 (1.80) 0.059 (1.50) PIN 1 6 1 5 2 4 3 0.118 (3.00) 0.098 (2.50) 0.037 (0.95) BSC 0.075 (1.90) BSC 0.051 (1.30) 0.035 (0.90) 0.059 (0.15) 0.000 (0.00) 0.057 (1.45) 0.035 (0.90) 0.020 (0.50) SEATING 0.010 (0.25) PLANE 10° 0.009 (0.23) 0° 0.003 (0.08) 0.022 (0.55) 0.014 (0.35) REV. A –11– PRINTED IN U.S.A. C3455a–0–8/99 – 12– C3455a–0–8/99 PRINTED IN U.S.A.