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| AS2940 1A Low Dropout Voltage Regulators (PRELIMINARY INFORMATION) FEATURES * * * * * * * * * Output Current 1A Internal Short Circuit Current Limit Dropout Voltage 0.5V at 1A Output Extremely Tight Load and Line Regulation Very Low Temperature Coefficient Mirror Image Insertion protection Unregulated DC Input Can Withstand -20V Reverse Battery and +60V Positive Transients Direct Replacement For LM2940 Socket APPLICATIONS * * * * * * * * Battery powered Systems Cordless Telephones Automotive Electronics Portable / Palm Top / Notebook Computers Portable Consumer Equipment Portable Instrumentation SMPS Post-Regulator Voltage Reference PRODUCT DESCRIPTION The AS2940 is a low powered positive voltage regulator. The AS2940 offers 1A output current with dropout voltage of only 0.5V and over temperature dropout is up to 1V. The quiescent current is 30mA at differential output of 5V and output current of 1A. The higher quiescent current can be exist when the device is in dropout mode (VIN - VOUT < 3V). Other key additional features of this device includes higher output current, positive transient protection up to 60V (load dump), and ability to survive an unregulated input voltage transient of -20V below ground (reverse battery). The regulator will automatically shut down to protect both the internal circuits and the load. This device also features short circuit and thermal overload protection. The AS2940 is offered in a 3-pin TO-220 and TO-263 package compatible with other 5V regulators. This device offers a variety of output voltages: 3.3V, 5V and 12V. AS2940 is direct replacement to LM2940. ORDERING INFORMATION TO-263 3-PIN AS2940T-X TO-220 3-PIN AS2940U-X Oper. Temp. Range -40C to +125C X= Output Voltage (X = 3.3V, 5.0V) Consult factory for other fixed voltages. PIN CONNECTIONS TO-220-3 (U) TO-263-3 (T) AS2940 AS2940 1 2 3 1 2 3 VIN GND VOUT Top View VIN GND VOUT Front View Rev. 10/11/00 AS2940 ABSOLUTE MAXIMUM RATINGS Power Dissipation (Note 1) ..................... Internally Limited Lead Temperature (Soldering, 5 seconds) ..................260C Storage Temperature Range ...................... -65C to +150C Operating Junction Temperature Range .... -40C to +125C TO-220 JC ............................................................... 2 C/W TO-263 JC ............................................................... 2 C/W Input Supply voltage...................................... -26V to +60V Operating Input Supply voltage .........................+2V to 12V Shutdown Input Voltage ............................... -0.3V to +30V Error Comparator Output Voltage ................... -0.3 to +30V ELECTRICAL CHARACTERISTICS VIN = VO + 5V, IO = 1A, CO = 22 F, unless otherwise specified. Boldface applies over the entire operating temperature range of the indicated device. All other specifications apply for TA = TJ = 25C. Output Voltage (VO) Parameter Conditions Typ 5V AS2940 Limit (Note 5) 6.25V < VIN < 26V 4.85/4.75 5.15/5.25 50 50/80 50 AS2940 Limit (Note 6) 4.85/4.75 5.15/5.25 40/50 50/100 Units Output Voltage Line Regulation Load Regulation 5 mA < IO < 1A VO + 2V < VIN < 26V, IO = 5 mA 50 mA < IO < 1A AS2940, AS2940/833 AS2940C 100 mADC and 20 mArms, fO = 120 Hz VO + 2V < VIN < 26V, IO = 5 mA AS2940, AS2940/833 AS2940C VIN = VO + 5V IO = 1A 10 Hz - 100 kHz, IO = 5 mA fO = 120 Hz, 1 VRMS, IO = 100 ma AS2940 AS2940C fO = 1 kHz, 1 VRMS, IO = 5 mA IO = 1A IO = 100 mA 5.00 20 35 35 35 V V mV mV 1000/1000 m Output Impedance Quiescent Current 10 10 30 150 15/20 15 45/60 15/20 mA 50/60 700/700 mA VRMS Output Noise Voltage Ripple Rejection 72 72 60/54 60 60/50 dBMIN dBMIN mV/ 1000 Hr VMAX mVMAX Long Term Stability Dropout Voltage 20 0.5 110 0.8/1.0 150/200 0.7/1.0 150/200 Rev. 10/11/00 AS2940 ELECTRICAL CHARACTERISTICS VIN = VO + 5V, IO = 1A, CO = 22 F, unless otherwise specified. Boldface limits apply over the entire operating temperature range of the indicated device. All other specifications apply for TA = TJ = 25C. (Continued) Output Voltage (VO) Parameter Conditions Typ 5V AS2940 Limit (Note 5) 6.25V < VIN < 26V 1.6 60/60 40/40 55 -30 -30 -75 -55 45 -15/-15 -15 -50/-50 -45/-45 -45/-45 -15/-15 AS2940 Limit (Note 6) 1.5/1.3 Units Short Circuit Current Maximum Line Transient Reverse Polarity DC Input Voltage Reverse Polarity Transient Input Voltage (Note 7) RO = 100 AS2940, T < 100 ms AS2940/833, T < 20 ms AS2940C, T < 1 ms RO = 100 AS2940/833, T < 20 ms AS2940C RO = 100 AS2940, T < 100 ms AS2940/833, T < 20 ms AS2940C, T < 1 ms 1.9 75 A V V V ELECTRICAL CHARACTERISTICS VIN = VO + 5V, IO = 1A, CO = 22 F, unless otherwise specified. Boldface limits apply over the entire operating temperature range of the indicated device. All other specifications apply for TA = TJ = 25C. (Continued) Output Voltage (VO) Parameter Conditions Typ 12V AS2940 AS2940/883 Limit Limit (Note 5) (Note 6) 13.6V < VIN < 26V 11.64/11.40 11.64/11.40 12.36/12.60 12.36/12.60 120 75/120 Units Output Voltage Line Regulation Load Regulation 5 mA < IO < 1A VO + 2V < VIN < 26V, IO = 5 mA 50 mA < IO < 1A AS2940, AS2940/833 AS2940C 12.00 20 V V mV 55 55 120/200 120 120/190 mV Rev. 10/11/00 AS2940 ELECTRICAL CHARACTERISTICS VIN = VO + 5V, IO = 1A, CO = 22 F, unless otherwise specified. Boldface limits apply over the entire operating temperature range of the indicated device. All other specifications apply for TA = TJ = 25C. (Continued) Output Voltage (VO) Parameter Conditions Typ 12V AS2940 Limit (Note 5) 13.6V < VIN < 26V AS2940/833 Limit (Note 6) Units Output Impedance Quiescent Current Output Noise Voltage Ripple Rejection 100 mADC and 20 mArms, fO = 120 Hz VO +2V < VIN < 26V, IO = 5 mA AS2940, AS2940/883 AS2940C VIN = VO + 5V, IO = 1A 10 Hz - 100 kHz, IO = 5 mA fO = 120 Hz, 1 VRMS, IO = 100 mA AS2940 AS2940C fO = 1 kHz, 1 Vrms, IO = 5 mA IO = 1A IO = 100 mA (Note 7) RO = 100 AS2940, T < 100 ms AS2940/883, T < 20 ms AS2940C, T < 1 ms RO = 100 AS2940, AS2940/883 AS2940C RO = 100 AS2940, T < 100 ms AS2940/883, T < 20 ms AS2940C, T < 1 ms 80 1000/1000 m 10 10 30 360 15/20 15 45/60 15/20 50/60 1000/1000 mA mA VRMS 66 66 54/48 54 52/46 dB dB mV/ 1000 Hr V mV A Long Term Stability Dropout Voltage Short Circuit Current Maximum Line Transient 48 0.5 110 1.9 75 55 -30 -30 -75 -55 0.8/1.0 150/200 1.6 60/60 40/40 45 -15/-15 -15 -50/-50 -45/-45 -45/-45 -15/-15 0.7/1.0 150/200 1.6/1.3 V Reverse Polarity DC Input Voltage Reverse Polarity Transient Input Voltage V V Rev. 10/11/00 AS2940 ELECTRICAL CHARACTERISTICS Dropout Voltage 0.9 TJ = 25 C 1.0 VIN = VO + 5V, IO =1A, CO = 22 F, unless otherwise specified. Dropout Voltage INPUT-OUTPUT DIFFERENTIAL (V) 0.8 0.9 0.7 0.8 0.6 DROPOUT VOLTAGE (V) 0.7 1A 0.6 0.5 0.4 0.5 0.3 0.4 500 mA 0.3 0.2 0.1 0.2 100 mA 0 0 200 400 600 800 1000 0.1 OUTPUT CURRENT (mA) 0 -40 0 40 80 120 160 TEMPERATURE (C) Output Voltage vs. Temperature 5.10 50 Quiescent Current vs. Temperature VIN = VO +5V 5.08 5.04 5.02 QUIESCENT CURRENT (mA) 5.06 40 OUTPUT VOLTAGE (5V) 30 1A 5.00 4.98 20 500 mA 4.96 10 mA 4.94 10 4.92 4.90 -40 0 40 80 120 160 0 -40 0 40 80 120 160 TEMPERATURE (C) TEMPERATURE (C) Quiescent Current 200 50 Quiescent Current 180 QUIESCENT CURRENT (mA) 140 120 QUIESCENT CURRENT (mA) 160 40 30 100 VIN = 14V VO = 5V TJ = 25 C 20 80 100 mA 60 500 mA 40 1A 10 20 0 0 5 10 15 20 25 30 35 0 0 0.2 0.4 0.6 0.8 1.0 Rev. 10/11/00 AS2940 ELECTRICAL CHARACTERISTICS VIN = VO + 5V, IO =1A, CO = 22 F, unless otherwise specified. Quiescent Current 30 0.5 Load Transient Response OUTPUT VOLTAGE DEVIATION (V) 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 VIN = 10V COUT = 22 F TJ = 25 C VO = 5V OUTPUT VOLTAGE DEVIATION (mV) 20 10 0 -10 -20 -30 INPUT VOLTAGE CHANGE (V) LOAD CURRENT (A) ~ ~ 3V ~ ~ -0.4 -0.5 1.0 ~ ~ ~ ~ 0.5 0 -10 0V -10 0 10 20 30 40 50 60 0 10 20 30 40 TIME (s) TIME (s) Ripple Rejection 95 VIN = 10V COUT = 22 F TJ = 10 mA VO = 5V 10.00 VIN = 10V COUT = 22 F TJ = 50 mA VO = 5V Output Impedance 5.00 85 RIPPLE REJECTION (dB) 2.00 75 OUTPUT IMPEDANCE () 1 10 100 1k 10k 100k 1M 1.00 65 0.50 55 0.20 0.10 45 0.05 35 0.02 FREQUENCY (Hz) 0.01 1 10 100 1k 10k 100k 1M FREQUENCY (Hz) Maximum Power Dissipation (TO-220) 22 INFINITE HEAT SINK 20 18 16 20 18 16 22 Maximum Power Dissipation (TO-3) INFINITE HEAT SINK Maximum Power Dissipation (TO-263) (See Note 3) 4 JA = 32 C/W POWER DISSIPATION (W) POWER DISSIPATION (W) 14 12 10 8 6 4 2 0 0 10 20 30 40 50 60 70 80 90 100 NO HEAT SINK 10 C/W HEAT SINK 14 12 10 10 C/W HEAT SINK 8 6 4 2 NO HEAT SINK 0 0 10 20 30 40 50 60 70 80 90 100 POWER DISSIPATION (W) 3 JA = 37 C/W 2 JA = 50 C/W 1 JA = 73 C/W 0 0 10 20 30 40 50 60 70 80 90 100 AMBIENT TEMPERATURE ( C) AMBIENT TEMPERATURE ( C) AMBIENT TEMPERATURE ( C/W) Rev. 10/11/00 AS2940 ELECTRICAL CHARACTERISTICS VIN = VO + 5V, IO =1A, CO = 22 F, unless otherwise specified. Low Voltage Behavior 5.0 14 Low Voltage Behavior 18 IO = 1A TJ = 25 C VO = 8V IO = 1A TJ = 25 C VO = 9V Low Voltage Behavior OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 4.0 10 8 6 4 2 0 0 2 4 6 8 10 12 14 OUTPUT VOLTAGE (V) INPUT VOLTAGE (V) IO = 1A TJ = 25 C VO = 5V 12 15 12 3.0 9 6 2.0 3 1.0 1.0 2.0 3.0 4.0 5.0 6.0 0 0 3 6 9 12 15 18 INPUT VOLTAGE (V) INPUT VOLTAGE (V) Low Voltage Behavior 18 14 IO = 1A TJ = 25 C VO = 10V 12 10 8 6 4 2 3 0 0 0 0 3 6 9 12 15 18 2 Low Voltage Behavior 18 IO = 1A TJ = 25 C VO = 12V IO = 1A TJ = 25 C VO = 15V Low Voltage Behavior OUTPUT VOLTAGE (V) 12 OUTPUT VOLTAGE (V) 4 6 8 10 12 14 15 OUTPUT VOLTAGE (V) 15 12 9 9 6 6 3 INPUT VOLTAGE (V) 0 0 3 6 9 12 15 18 INPUT VOLTAGE (V) INPUT VOLTAGE (V) Output at Voltage Extremes 12 20 Output at Voltage Extremes 20 Output at Voltage Extremes OUTPUT VOLTAGE (V) 16 12 8 4 0 -4 RL = 100 VO = 9V OUTPUT VOLTAGE (V) 8 6 4 2 0 -2 -30 -20 -10 0 10 20 30 40 OUTPUT VOLTAGE (V) 10 RL = 100 VO = 5V 16 12 8 4 0 -4 -30 RL = 100 VO = 8V -20 -10 0 10 20 30 40 -30 -20 -10 0 10 20 30 40 INPUT VOLTAGE (V) INPUT VOLTAGE (V) INPUT VOLTAGE (V) Output at Voltage Extremes 25 Output at Voltage Extremes 20 25 Output at Voltage Extremes OUTPUT VOLTAGE (V) 20 15 10 5 0 -5 RL = 100 VO = 15V OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 20 15 10 5 0 -5 -30 RL = 100 VO = 10V 16 12 8 4 0 -4 -30 RL = 100 VO = 12V -20 -10 0 10 20 30 40 -30 -20 -10 0 10 20 30 40 -20 -10 0 10 20 30 40 INPUT VOLTAGE (V) INPUT VOLTAGE (V) INPUT VOLTAGE (V) Output Capacitor ESR 100 COUT = 22 F VO = 5V 3.0 Peak Output Current EQUIVALENT SERIES RESISTANCE ( ) 10 OUTPUT CURRENT (A) 2.0 VIN = 14V 1 STABLE REGION 0.1 1.0 0.01 0 200 400 600 800 1000 0 -40 0 40 80 120 160 OUTPUT CURRENT (mA) TEMPERATURE ( C) Rev. 10/11/00 AS2940 APPLICATION HINTS External Capacitors A minimum capacitance of 22F and conditions on ESR (Equivalent Series Resistance) must be met. The minimum value for the capacitance is 22F and can be increased without limit. However the ESR may cause loop instability if it is too high or too low. The following graph shows the acceptable range for the ESR. Output Capacitor ESR 100 COUT = 22 F VO = 5V EQUIVALENT SERIES RESISTANCE () 10 1 STABLE REGION 0.1 0.01 0 200 400 600 800 1000 OUTPUT CURRENT (mA) If the capacitor does not meet these requirements oscillation can result. ESR is specified only at room temperature. Therefore the designer must ensure the proper behavior of the ESR over the temperature range. ESR, for electrolytic capacitor, will increase by about 30X as the temperature is reduced from 25C to -40C. Aluminum electrolytic capacitors are not well suited for low temperature operation. Solid tantalum capacitors' ESR are more stable over temperature, but expensive. A cost-effective approach is then to put in parallel a solid tantalum and a aluminum electrolytic capacitors in the ratio25/75%. Thermal Consideration Although the AS2940 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. Formulas for calculating the power dissipated in the regulator are the following: IIN = IL + IG PD = (VIN + VOUT) * IL + VIN * IG Where IIN is the input current, IL is the load current, IG is the ground current, PD is the power dissipated, VIN is the input voltage and VOUT is the output voltage. Rev. 10/11/00 |
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