AS2830YU-X

AS2830 3A Low Dropout Voltage Regulator Adjustable & Fixed Output, Fast Response FEATURES • Adjustable Output Down To 1.2V • Fixed Output Voltages 1.5, 2.5, 3.3, 5.0V • Output Current Of 3A • Low Dropout Voltage 1.1V Typ. • Extremely Tight Load And Line Regulation • Current & Thermal Limiting • Standard 3-Terminal Low Cost TO-220, TO-263 & TO-252 • Similar To Industry Standard LT1085/LT1585 APPLICATIONS • Powering VGA & Sound Card • Power PCSupplies • SMPS Post-Regulator • High Efficiency “Green” Computer Systems • High Efficiency Linear Power Supplies • Portable Instrumentation • Constant Current Regulators • Adjustable Power Supplies • Battery charger PRODUCT DESCRIPTION The AS2830 is a low power 3A adjustable and fixed voltage regulator that is very easy to use. It requires only 2 external resistors to set the output voltage for adjustable version. The AS2830 are designed for low voltage applications that offers lower dropout voltage and faster transient response. This device is an excellent choice for use in powering low voltage microprocessor that require a lower dropout, faster transient response to regulate from +2.5V to 3.8V supplies and as a post regulator for switching supplies applications. The AS2830 features low dropout of a maximum 1.2 volts. The AS2830 offers over current limit and full protection against reversed input polarity, reversed load insertion, and positive and negative transient voltage. On-Chip trimming adjusts the reference voltage to 1%. The IQ of this device flows into the load, which increases efficiency. The AS2830 are offered in a 3-pin TO-220, TO-263 & TO-252 packages compatible with other 3 terminal regulators. For a 5A low dropout regulator refer to the AS2850 data sheet. ORDERING INFORMATION TO-220 3-PIN AS2830YU-X DD PLASTIC 3-PIN AS2830YT-X TO-252 DPAK AS2830YR-X PIN CONNECTIONS TO-263-3 (T) TO-220-3 (U) TO-252 (R) X = Output Voltage (1.5V, 2.5V, 3.3V, 5.0V and Blank for Adj.) Y= Output Tolerance, (Y= A for 1% Blank for 2%) AS2830 1 2 3 AS2830 1 2 3 AS2830 1 2 3 ADJ/GND VOUT VIN ADJ/GND VOUT VIN Front View ADJ/GND VOUT VIN Top View Front View Rev. 10/6/00 AS2830 ABSOLUTE MAXIMUM RATINGS Lead Temp. (Soldering, 10 Seconds) .............................. 300°C Storage Temperature Range ............................ -65° to +150°C Operating Junction Temperature Range ...................... AS2830 Control Section ............................ -45°C +125°C AS2830 Power Transistor...........................-45°C +150°C Maximum Input Voltage ...................................... 10V Input to Output Voltage Differential Max ........... 8.8V ELECTRICAL CHARACTERISTICS (NOTE 1) at IOUT = 10mA, TA=25°C, unless otherwise specified. AS2830A AS2830 PARAMETER CONDITIONS Typ Min Max Min 1.5V Version Output Voltage (Note 2) 2.5V Version Output Voltage (Note 2) 3.3V Version Output Voltage (Note 2) 5.0V Version Output Voltage (Note 2) All Voltage Options Reference Voltage (VREF) AS2830-1.5V, 0 ≤IOUT≤3A, 2.75V≤VIN ≤10V 1.5 1.5 2.5 2.5 3.3 3.3 5.0 5.0 1.485 1.470 2.475 2.450 3.270 3.240 4.95 4.90 1.238 1.225 1.515 1.530 2.525 2.550 3.330 3.360 5.05 5.10 1.263 1.270 10 0.2 0.2 0.3 0.3 1.2 1.470 1.455 2.450 2.425 3.230 3.201 4.900 4.850 1.225 1.212 Max 1.530 1.545 2.550 2.575 3.370 3.399 5.100 5.150 1.270 1.288 10 0.2 0.2 0.3 0.3 1.2 Units V AS2830-2.5V, 0 ≤IOUT≤3A, 4.0V≤VIN ≤10V V AS2830-3.3V, 0 ≤IOUT≤3A, 4.75V≤VIN ≤10V AS2830-5.0V, 0 ≤IOUT≤3A, 6.5V≤VIN ≤10V VIN≤ 7V, P≤ PMAX 1.5V≤ (VIN -VOUT)≤(VIN-VOUT) MAX, 10mA≤IOUT≤3A 1.5V≤ (VIN -VOUT)≤ (VIN-VOUT) MAX 2.75V≤VIN ≤7V, IOUT=10mA, TJ=25°C (Note 3) VIN ≤7V, IOUT=0mA, TJ=25°C (Note 2) 10mA≤IOUT ≤3A, (VIN-VOUT)=3V, TJ=25°C (Note 3) 0≤IOUT ≤3A, VIN=7V, TJ=25°C (Note 2) IOUT =3A ∆VREF=1% IOUT≤ 3A VIN=7V 1.4V≤ (VIN- VOUT) (Note3) TA=125°C, 1000 Hrs. TA=25°C, 20 ms pulse V V V 1.250 5 0.005 0.005 0.05 0.05 1.1 Min. Load Current (Note 3) Line Regulation (∆VREF (VIN)) mA % % % % V A Load Regulation (∆VREF (IOUT)) Dropout Voltage Current Limit IOUT (MAX) Long Term Stability Thermal Regulation (∆VOUT (Pwr)) Temperature Stability (∆VOUT (T)) Output Noise, RMS Thermal Resistance 4.0 0.3 (Note 2) 0.01 0.25 3.2 1 0.020 3.2 1 0.020 % %/W % %V °C/W 10Hz to 10kHz TA = 25°c Junction to Tab TO-220 Junction to Ambient Junction to Tab DD Package Junction to Ambient 0.003 3.0 60 3.0 60 3.0 60 3.0 60 The Bold specifications apply to the full operating temperature range. Note 1: Changes in output voltage due to heating effects are covered under the specification for thermal regulation. Note 2: Fixed Version Only Note 3: Adjustable Version Only Rev. 10/6/00 AS2830 APPLICATION HINTS The AS2830 incorporates protection against over-current faults, reversed load insertion, over temperature operation, and positive and negative transient voltage. However, the use of an output capacitor is required in order to improve the stability and the performances. Stability The output capacitor is part of the regulator’s frequency compensation system. Either a 22µF aluminum electrolytic capacitor or a 10µF solid tantalum capacitor between the output terminal and ground guarantees stable operation for all operating conditions. However, in order to minimize overshoot and undershoot, and therefore optimize the design, please refer to the section ‘Ripple Rejection’. Ripple Rejection Ripple rejection can be improved by adding a capacitor between the ADJ pin and ground as shown in figure 6. When ADJ pin bypassing is used, the value of the output capacitor required increases to its maximum (22µF for an aluminum electrolytic capacitor, or 10µF for a solid tantalum capacitor). If the ADJ pin is not bypass, the value of the output capacitor can be lowered to 10µF for an electrolytic aluminum capacitor or 4.7µF for a solid tantalum capacitor. However the value of the ADJ-bypass capacitor should be chosen with respect to the following equation: C = 1 / (6.28 * FR * R1) Where C = value of the capacitor in Farads (select an equal or larger standard value), FR = ripple frequency in Hz, R1 = value of resistor R1 in Ohms. If an ADJ-bypass capacitor is use, the amplitude of the output ripple will be independent of the output voltage. If an ADJbypass capacitor is not used, the output ripple will be proportional to the ratio of the output voltage to the reference voltage: M = VOUT / VREF Where M = multiplier for the ripple seen when the ADJ pin is optimally bypassed. VREF = Reference Voltage Reducing parasitic resistance and inductance One solution to minimize parasitic resistance and inductance is to connect in parallel capacitors. This arrangement will improve the transient response of the power supply if your system requires rapidly changing current load condition. Thermal Consideration Although the AS2830 offers some limiting circuitry for overload conditions, it is necessary not to exceed the maximum junction temperature, and therefore to be careful about thermal resistance. The heat flow will follow the lowest resistance path, which is the Junction-to-case thermal resistance. In order to insure the best thermal flow of the component, a proper mounting is required. Note that the case of the device is electrically connected to the output. In case the case has to be electrically isolated, a thermally conductive spacer can be used. However do not forget to consider its contribution to thermal resistance. Assuming: VIN = 10V, VOUT = 5V, IOUT = 1.5A, TA = 50°C/W, θ Heatsink Case = 6°C/W, θ Heatsink Case = 0.5°C/W, θ JC = 3°C/W Power dissipation under this condition PD = (VIN – VOUT) * IOUT = 7.5W Junction Temperature TJ = TA + PD * (θ Case - HS+ θ HS + θ JC) For the Control Sections TJ = 50 + 7.5*(0.5 +6=3) = 121.25°C 121.25°C < TJ (max) for the Control & Power Sections. In both case reliable operation is insured by adequate junction temperature. Rev. 10/6/00 AS2830 Basic Adjustable Regulator VIN AS2830 VREF IADJ 50µA VOUT R1 VIN 5V AS2830 C1 10uF VOUT 3.3V C2 10uF R2 VOUT = VREF * ( 1 + R /R1) + IADJ * R2 2 Basic Fixed Regulator Fig.2 Basic Adjustable Regulator Output Voltage Consider Figure 2. The resistance R1 generates a constant current flow, normally the specified load current of 10mA. This current will go through the resistance R2 to set the overall output voltage. The current IADJ is very small and constant. Therefore its contribution to the overall output voltage is very small and can generally be ignored. Load Regulation Parasitic line resistance can degrade load regulation. In order not to affect the behavior of the regulator, it is best to connect directly the R1 resistance from the resistor divider to the case, and not to the load. For the same reason, it is best to connect the resistor R2 to the Negative side of the load. RP Parasitic Line Resistance Output Voltage The fixed voltage LDO voltage regulators are simple to use regulators since the VOUT is preset to the specifications. It is important however, to provide the proper output capacitance for stability and improvement. For most operating conditions a capacitance of 22uF tantalum or 100uF electrolytic will ensure stability and prevent oscillation. VIN AS2830 Connect R to 1 Case of Regulator R1 RL R2 Connect R to Load 2 Fig.3 Basic Adjustable Regulator Rev. 10/2/00 AS2830 TYPICAL APPLICATIONS VIN C1 VIN IN AS2830 ADJ OUT C1 R1 IN AS2830 ADJ OUT R1 C2 VOUT LOAD VOUT = VREF (1 + R2 ) + IADJ R2 R1 R2 Fig. 4 3A Current output Regulator Fig. 5 Typical Adjustable Regulator (Note A) VIN IN 5V + 10µF AS2830 ADJ OUT VOUT R1 121Ω 1% 150µF VIN (Note A) + IN AS2830 ADJ OUT 5V 121Ω 1% + 100µF 10µF 1k 2N3904 1k 365Ω 1% *C 1 improves ripple rejection. XC should be ~ R 1 at ripple frequency. R2 365Ω 1% TTL Input + C1 10µF* Note A: V IN(MIN) = (Intended V OUT) + (VDROPOUT (MAX)) Note A: VIN(MIN)= (Intended V ) + (VDROPOUT (MAX)) OUT Fig. 6 Improving Ripple Rejection Fig.7 5V Regulator with Shutdown Rev. 10/2/00 AS2830 TYPICAL CHARACTERISTICS Rev. 10/2/00