LM2940_[www.ic5.cn]

Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com 1.25A High Current Low Dropout LM2940/2941 Voltage Regulator Adjustable Pin Connection Ordering Information Devices Package Temp. LM2940T TO-220-3 -40 °C to 125 °C LM2941T TO-220-5 -40 °C to 125 °C LM2940S TO-263-3 -40 °C to 125 °C LM2941S TO-263-5 -40 °C to 125 °C LM2940N SOT-223-3 -40 °C to 125 °C LM2941N SOT-223-5 -40 °C to 125 °C LM2940J LPDD-3 -40 °C to 125 °C LM2941J LPDD-5 -40 °C to 125 °C Description The Bay Linear LM2940 & LM2941 is a 1.25A high accuracy, low dropout voltage regulator with only 40mV at light loads and 350mV(Typ.)@ 1.0A) and low quiescent current of 240µA typical. The LM2940/41 is designed for low voltage a application that requires lower dropout voltage and faster transient response. This device is an excellent choice for use in powering low voltage applications where 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 LM2940/41 offers full protection against over-current faults, reversed input polarity, reversed load insertion, and positive and negative transient voltage. On-Chip trimming adjusts the reference voltage to 1%. The LM2940-xx devices are in 3 pin fixed voltage regulators. The LM2941 include an Enable pin in the 5 pin packages. The LM2940/41 are offered in a 3 & 5-pin SOT-223, TO-220 & TO-263 package compatible with other 3 terminal regulators. The LM2940/41 is also offer in a new LPDD (Low Profile TO-263) package from 4.47 mm (DD) tickness down to only 1.27 mm (LPDD) t t l ti k Features • High output accuracy of 1% • Output Adjustable from 1.24V to 26V • Output Current of 1.25A • Low Dropout Voltage • Low quiescent current • Extremely Tight Load & Line Regulation • Reverse-battery and “Load Dump” Protection • Zero Current Shutdown Mode (5-pin version) • Offer in TO-263, TO-220, SOT-223, & New Slim LPDD • Similar to industry Standard MIC2940LM2941 Applications • Powering VGA & Sound Card • LCD Monitor • Battery Powered Equipments/Laptop & Notebook • SMPS Post Regulator / DC to DC Modules • High Efficiency Linear Power Supply • Adjustable Power Supply • Bar Code Scanners Bay Linear Inspire the Linear Power TO-263-3 Package VOUTGNDVIN BAY B2940 Front View 1 2 3 Front View TO-220-3 Package BAY B2940 V IN VOUTGND TO-263-5 Package Top View 4 5 BAY B2941 321 GND OUPUT 1) 3) 4) 5) 2) ON/OFF ADJUST INPUT TO-220-5 Package Top View BAY B2941 1 2 3 4 5 TO-263-3 Package VOUTGNDVIN BAY B2940 Front View 1 2 3 Front View TO-220-3 Package BAY B2940 V IN VOUTGND TO-263-3 Package VOUTGNDVIN BAY B2940 Front View 1 2 3 Front View TO-220-3 Package BAY B2940 V IN VOUTGND Front View TO-220-3 Package BAY B2940 V IN VOUTGND TO-263-5 Package Top View 4 5 BAY B2941 321 GND OUPUT 1) 3) 4) 5) 2) ON/OFF ADJUST INPUT TO-220-5 Package Top View BAY B2941 1 2 3 4 5 TO-263-5 Package Top View 4 5 BAY B2941 321 GND OUPUT 1) 3) 4) 5) 2) ON/OFF ADJUST INPUT GND OUPUT 1) 3) 4) 5) 2) ON/OFF ADJUST INPUT TO-220-5 Package Top View BAY B2941 1 2 3 4 5 TO-220-5 Package Top View BAY B2941 1 2 3 4 5 Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com LM2940/41 ABSOLUTE MAXIMUM RATINGS Lead Temp. (Soldering, 5 Seconds).................................260°C Input Voltage ........................................................26V Storage Temperature Range.............................. -65° to +150°C Maximum Output Current....................................3.5A Operating Junction Temperature Range Input Supply Voltage (Note1) (Survival)-20V to +60V LM2940/2941 Control Section.................. -45°C +125°C LM2940/2941 Power Transistor................. -45°C +150°C ELECTRICAL CHARACTERISTICS (NOTE 1) at IOUT = 5mA, V IN =V OUT + 1V, I l = 1000mA, C L = 10µF. Ta=25°C, unless otherwise specified. The LM2941 is programmed to output 5V and has V SHUTDOWN ≤ 0.6V PARAMETER CONDITIONS Typ LM2940 Min Max Units 2.5V Version Output Voltage (Note 2) IOUT = 5mA 5mA ≤IOUT≤1.25A, 4.75V≤VIN ≤26V 2.5 2.5 2.475 2.450 2.525 2.550 V 3.3V Version2. Output Voltage (Note 2) IOUT = 5mA 5mA ≤IOUT≤1.25A, 4.75V≤VIN ≤26V 3.3 3.3 3.267 3.234 3.330 3.366 V 5.0V Version Output Voltage (Note 2) IOUT = 5mA 5mA ≤IOUT≤1.25A, 5.5V≤VIN ≤26V 5.0 5.0 4.95 4.90 5.05 5.10 V Output Voltage Accuracy 5mA ≤IOUT≤1.0 A -1 -2 -2.5 1 2 2.5 % All Voltage Options Line Regulation IO = 5mA, (VOUT + 1V) ≤ VIN≤ 26V 0.06 0.5 % Load Regulation VIN = VOUT + 5V, 5mA ≤ IOUT≤ 1 A (Note 2, 6) 0.2 1.6 % ∆V° 20 100 ppm/°C ∆T Output Voltage (Note 6) Temperature Coef. IO = 5mA 80 150 IO = 1000mA 350 450 Dropout Voltage IO = 1.25A 400 600 mV Ground Current IO = 5mA, VIN = VOUT, +1V IO = 1000mA, VIN = VOUT, +1V IO = 1.25A 240 22 35 350 35 70 µA mA IGNDDO Ground Pin Current at Dropout VIN = 0.5V less than specified VOUT IOUT = 10mA 0.9 mA Current Limit VOUT = 0V (Note 4) 1.7 1.5 A Output Noise Voltage (10Hz to 100kHz) IL = 100mA CL = 10µF CL = 33µF 400 260 µV RMS Reference Voltage 1.235 1.223 1.210 1.247 1.260 V Vmax Reference Voltage (Note 8)` 1.204 1.266 V Adjust Pin Bias Current 40 80 120 nA Reference Voltage Temperature Coefficient (Note 7) 20 ppm/°C Adjust Pin Bias Current Temperature Coefficient 0.1 nA/°C Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com LM2940/2941 ENABLE Input LM2941 Input Logic Voltage Low (OFF) High (ON) 2.4 0.8 V VEN = 26V 100 600 750 V Enable Pin Input Current VEN = 0.8V 2.5 5 µA Regulator Output Current in Shutdown (Note 10) 10 500 µA NOTES: The Bold specifications apply to the full operating temperature range. Note 1: Maximum positive supply voltage of 60V must be of limited duration (<100msec) and duty cycle.) The maximum continuous supply voltage is 26V. Note 2: Full load current (IFL) is defined as 1.25A for the LM2941. Note 3: Dropout voltage is defined as the input-to output differential when the output voltage drops to 99% of its nominal value with VOUT + 1V applied to VIN. Note 4: VIN = VOUT (NOMINAL) +1V. For example, use VIN= 4.3V for a 3.3V regulator. Employ pulse-testing procedures to minimize temperature rise. Note 5: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current to the ground current. Note 6: Output voltage temperature coefficient is defined as the worst case voltage changed divided by the total temperature range. Note 7: Thermal regulation is defined as the change in the output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation effects. Specifications are for a 200mA load pulse as VIN = 20V (a 4W pulse) for T = 10ms. Note 8: VREF ≤ VOUT ≤ (VIN - 1), 2.3V ≤ VIN≤ 26V, 10mA < IL ≤ IFL, TJ ≤ TJMAX Note 9: Comparator threshold is expressed in terms of a voltage differential at the Adjust terminal below the nominal reference voltage measured 6V input. To express these thresholds in terms of output voltage change, multiply the error amplifier gain = VOUT/VREF = (R1 + R2)/R2. For example, at a programmable output voltage of 5V, the Error output is guaranteed to go low when the output drops by 95mVx 5V/ 1.240V = 38mV. Threshold remains constant as a percent of VOUT as VOUT is varied, with the dropout warning occurring at typically 5% below nominal, 7.7% guaranteed. Note 10: VEN ≤ 0.8V and VIN≤ 26V, VOUT = 0. BLOCK DIAGRAM Reference Thermal Shutdown EN IN OUT ADJ GND O.V ILIMIT 28V R1* R2* 1.180V 1.240V ++ - - FLAG Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com LM2940/2941 APPLICATION HINTS The Bay Linear LM2941 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 insure the stability and the performances. Thermal Consideration Although the LM2941 offers 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. 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 = 90°C, θCASE= 1°C/W (no external heat sink, no wind) Power dissipation under these conditions PD = (VIN – VOUT) * IOUT = 7.5W Junction Temperature TJ = TA + PD * (θCASE+ θJC) For the Control Section TJ = 90°C + 7.5W*(1°C/W + 0.6°C/W) = 102°C 114°C < TJUNCTION MAX for the control section. For the Power Section TJ = 90°C + 7.5W*(1°C/W + 1.6°C/W) = 104.5°C 109.5°C < TJUNCTION MAX for the power transistor. In both case reliable operation is insured by adequate junction temperature. Capacitor Requirements The output capacitor is needed for stability and to minimize the output noise. The required value of the capacitor varies with the load. However, a minimum value of 10µF Aluminum will guarantee stability over load. A tantalum capacitor is recommended for a fast load transient response. If the power source has high AC impedance, a 0.1µF capacitor between input & ground is recommended. This capacitor should have good characteristics up to 250 kHz. Minimum Load Current To ensure a proper behavior of the regulator at light load, a minimum load of 5mA for LM2941 is required. Adjustable Regulator Design B29152/53 are adjustable regulators and maybe programmed for any value between 1.25V and 26V using two resistors. The relation between the resistors is given by: R1=R2 (VOUT/1.240 –1) Resistors have a large value up to 1mΩ in order to reduce the current consumption. This might be interesting in the case of widely varying load currents. Enable Input LM2941 features enable input allowing turning ON & OFF the device. EN has been designed to be compatible with TTL/CMOS logic. When the regulator is ON, the current flowing through this pin is approximately 20µA. 4 53 2 1 BAY B2941 VOUT VIN R1 R2 Fig. 2 Adjustable Output Voltage Regulator VOUT = VREF X [1 + (R1/ R2)] For best results, the total series resistance should be small enough to pass the minimum regulator load current 4 53 2 1 BAY B2941 VOUT VIN R1 R2 Fig. 2 Adjustable Output Voltage Regulator VOUT = VREF X [1 + (R1/ R2)] For best results, the total series resistance should be small enough to pass the minimum regulator load current BAY B2940 Fig.1 Basic Fixed Output Regulator V OU TVIN BAY B2940 Fig.1 Basic Fixed Output Regulator V OU TVIN Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 989-7144, Fax: (925) 940-9556 www.baylinear.com LM2940/2941 Advance Information- These data sheets contain descriptions of products that are in development. The specifications are based on the engineering calculations, computer simulations and/ or initial prototype evaluation. Preliminary Information- These data sheets contain minimum and maximum specifications that are based on the initial device characterizations. These limits are subject to change upon the completion of the full characterization over the specified temperature and supply voltage ranges. The application circuit examples are only to explain the representative applications of the devices and are not intended to guarantee any circuit design or permit any industrial property right to other rights to execute. Bay Linear takes no responsibility for any problems related to any industrial property right resulting from the use of the contents shown in the data book. Typical parameters can and do vary in different applications. Customer’s technical experts must validate all operating parameters including “ Typical” for each customer application. LIFE SUPPORT AND NUCLEAR POLICY Bay Linear products are not authorized for and should not be used within life support systems which are intended for surgical implants into the body to support or sustain life, in aircraft, space equipment, submarine, or nuclear facility applications without the specific written consent of Bay Linear President.