MIC2940A/2941A 1.2A Low-Dropout Voltage Regulator General Description Features The MIC2940A and MIC2941A are "bulletproof" efficient voltage regulators with very low dropout voltage (typically 40mV at light loads and 350mV at 1A), and low quiescent current (240A typical). The quiescent current of the MIC2940A increases only slightly in dropout, thus prolonging battery life. Key MIC2940A features include protection against reversed battery, fold-back current limiting, and automotive "load dump" protection (60V positive transient). The MIC2940 is available in both fixed voltage (3.3V, 5V, and 12V) and adjustable voltage configurations. The MIC2940A-xx devices are three pin, fixed voltage regulators. A logic-compatible shutdown input is provided on the adjustable MIC2941A, which enables the regulator to be switched on and off. Data sheets and support documentation can be found on Micrel's web site at: www.micrel.com. * * * * * * * * High output voltage accuracy Guaranteed 1.25A output Low quiescent current Low dropout voltage Extremely tight load and line regulation Very low temperature coefficient Current and thermal limiting Input can withstand -20V reverse battery and +60V positive transients * Logic-controlled electronic shutdown * Output programmable from 1.24V to 26V(MIC2941A) * Available in TO-220, TO-263, TO-220-5, and TO-263-5 packages. Applications * Battery powered equipment * Cellular telephones * Laptop, notebook, and palmtop computers * PCMCIA VCC and VPP regulation/switching * Bar code scanners * Automotive electronics * SMPS post-regulator/ DC-to-DC modules * Voltage reference * High efficiency linear power supplies ___________________________________________________________________________________________________________ Pin Configuration 1 2 3 TO-263-3 (MIC2940A-xxBU/WU) 1 2 3 TO-220-3 (MIC2940A-xxBT/WT) MIC2940A Pinout 1) Input 2) Ground 3) Output 1 2 3 4 5 TO-263-5 (MIC2941ABU/WU) MIC2941A Pinout 1) Adjust 2) Shutdown 3) Ground 4) Input 5) Output 1 2 3 4 5 TO-220-5 (MIC2941ABT/WT) The TAB is Ground on TO-220 and TO-263 packages Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com July 2007 M9999-071307 Micrel, Inc. MIC2940A/2941A Ordering Information Part Number Voltage Temperature Range Package Lead Finish MIC2940A-3.3BT 3.3V -40 to +125C 3-Pin TO-220 Standard MIC2940A-3.3BU 3.3V -40 to +125C 3-Pin TO-263 Standard MIC2940A-3.3WT 3.3V -40 to +125C 3-Pin TO-220 RoHS Comliant(1) MIC2940A-3.3WU 3.3V -40 to +125C 3-Pin TO-263 RoHS Comliant(1) MIC2940A-5.0BT 5V -40 to +125C 3-Pin TO-220 Standard MIC2940A-5.0BU 5V -40 to +125C 3-Pin TO-263 Standard MIC2940A-5.0WT 5V -40 to +125C 3-Pin TO-220 RoHS Comliant(1) MIC2940A-5.0WU 5V -40 to +125C 3-Pin TO-263 RoHS Comliant(1) MIC2940A-12BT 12V -40 to +125C 3-Pin TO-220 Standard MIC2940A-12BU 12V -40 to +125C 3-Pin TO-263 Standard MIC2940A-12WT 12V -40 to +125C 3-Pin TO-220 RoHS Comliant(1) MIC2940A-12WU 12V -40 to +125C 3-Pin TO-263 RoHS Comliant(1) MIC2941ABT Adj. -40 to +125C 5-Pin TO-220 Standard MIC2941ABU Adj. -40 to +125C 5-Pin TO-263 Standard MIC2941AWT Adj. -40 to +125C 5-Pin TO-220 RoHS Comliant(1) MIC2941AWU Adj. -40 to +125C 5-Pin TO-263 RoHS Comliant(1) Note: 1. RoHS compliant with `hot-melting solder' exemption. Schematic Diagram July 2007 2 M9999-071307 Micrel, Inc. MIC2940A/2941A Absolute Maximum Ratings If Military/Aerospace specified devices are required, contact your local Micrel representative/distributor for availability and specifications Power Dissipation (Note 1) .......................Internally Limited Lead Temperature (soldering, 5 sec.)........................ 260C Storage Temperature ................................-65C to +150C Operating Junction Temperature ..............-40C to +125C TO-220 (JC) ........................................................2C/W TO-263 (JC) ........................................................2C/W Input Supply Voltage ...................................... -20V to +60V Operating Input Supply Voltage .......................... 2V to 26V Adjust Input Voltage (Notes 9 and 10) ......... -1.5V to +26V Shutdown Input Voltage ................................ -0.3V to +30V Error Comparator Output Voltage ................. -0.3V to +30V Across the full operating temperature, the minimum input voltage range for full output current is 4.3V to 26V. Output will remain in-regulation at lower output voltages and low current loads down to an input of 2V at 25C. Electrical Characteristics Limits in standard typeface are for TJ = 25C and limits in boldface apply over the full operating temperature range. Unless otherwise specified, VIN = VOUT + 1V, IL = 1000mA, CL = 10F. The MIC2941A is programmed to output 5V and has VSHUTDOWN 0.6V. Symbol Parameter VO Output Voltage Accuracy Condition Min 5 mA IL 1A -1 -2 -2.5 Typ Max Units 1 2 2.5 % % % 20 100 ppm/C VO T Output Voltage Temperature Coefficient (Note 2) VO VO Line Regulation IO = 10mA, (VOUT + 1V) VIN 26V 0.06 0.50 % Load Regulation IL = 5mA to 1.25A IL = 5mA to 1A (Note 3) 0.04 0.16 0.20 % % VIN - VO Dropout Voltage (Note 4) IL = 5mA 60 IL = 250mA 200 IL = 1000mA 350 IL = 1250mA 400 150 180 250 320 450 600 600 mV mV mV mV mV mV mV IL = 5mA 240 500 A IL = 250mA 3 IL = 1000mA 22 IL = 1250mA 35 4.5 6 35 45 70 mA mA mA mA mA IGND Ground Pin Current (Note 5) IGNDDO Ground Pin Current at Dropout (Note 5) VIN = 0.5V less than designed VOUT (VOUT 3.3) IL = 5mA 330 600 A ILIMIT Current Limit VOUT = 0V (Note 6) 1.6 3.5 A VO PD Thermal Regulation (Note 7) 0.05 0.2 %/W en Output Noise Voltage (10Hz to 100kHz) IL = 100mA CL = 10F CL = 33F 400 260 July 2007 3 VRMS VRMS M9999-071307 Micrel, Inc. MIC2940A/2941A Electrical Characteristics (MIC2941A Only) Parameter Condition Min Typ Max Units 1.223 1.210 1.204 1.235 1.247 1.260 1.266 V V V Adjust Pin Bias Current 20 40 60 nA nA Reference Voltage Temperature Coefficient 20 ppm/C Adjust Pin Bias Current Temperature Coefficient 0.1 nA/C 1.3 0.7 V V V Reference Voltage (Note 8) Shutdown Input Input Logic Voltage Low (ON) High (OFF) Shutdown Pin Input Current Regulator Output Current in Shutdown 2.0 VSHUTDOWN = 2.4V 30 50 100 A A VSHUTDOWN = 26V 450 600 750 A A 3 30 60 A A (Note 10) Notes: 1. Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the device outside of its rated operating conditions. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal resistance, JA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: P(MAX) = (TJ(MAX) - TA) / JA. Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. 2. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. 3. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 4. Dropout Voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V differential. At low values of programmed output voltage, the minimum input supply voltage of 4.3V over temperature must be taken into account. 5. Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground pin current. 6. The MIC2940A features fold-back current limiting. The short circuit (VOUT = 0V) current limit is less than the maximum current with normal output voltage. 7. Thermal regulation is defined as the change in 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 at VIN = 20V (a 4W pulse) for T = 10ms. 8. VREF VOUT (VIN - 1 V), 4.3V VIN 26V, 5mA < IL 1.25A, TJ TJ(MAX). 9. Circuit of Figure 3 with R1 150k . VSHUTDOWN 2 V and VIN 26 V,VOUT = 0. 10. When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode clamped to ground. 11. Maximum positive supply voltage of 60 V must be of limited duration (< 100 ms) and duty cycle ( 1%). The maximum continuous supply voltage is 26V. July 2007 4 M9999-071307 Micrel, Inc. MIC2940A/2941A Typical Characteristics DROPOUT VOLTAGE (mV) 100 1 11 200 0 0 100 1000 10000 10A OUTPUT CURRENT (mA) 0.30 0.20 ILOAD = 5mA 0.10 2.0 0.00 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) Fixed 3.3V Output Voltage vs. Temperature 2 3 4 5 6 7 SUPPLY VOLTAGE (V) Ground Current vs. Temperature ILOAD = 100mA 0.8 0.6 0.4 0.2 2.0 1.8 1.6 3.34 3.32 1.4 1.2 VOUT = VNOMINAL - 0.5V 1.0 VOUT = 0V 3.24 3.22 0.4 0.2 FIXED 3.3V VERSION 3 SAMPLES 3.20 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) 0.0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) July 2007 5 2 ILOAD = 1.25A 1 0 1 2 3 4 5 INPUT VOLTAGE (V) 6 Ground Current vs. Supply Voltage 40 30 20 10 FIXED 3.3V DEVICE ILOAD = 1.25A 0 2 4 6 8 INPUT VOLTAGE (V) 10 Ground Current vs. Temperature ILOAD = 1.25A 40 30 20 10 ILOAD = 100mA 0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) Short Circuit and Maximum Current vs. Temperature 0.8 0.6 3.28 3.26 3 50 1.4 1.2 1.0 ILOAD = 5mA 0 8 1.8 1.6 3.38 3.36 3.30 1 0.0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) CURRENT (A) OUTPUT VOLTAGE (V) 3.40 FIXED 5V ILOAD = 5mA 0 4 50 300 100 5 0 Ground Current vs. Supply Voltage 400 Ground Current vs. Temperature 0.40 ILOAD = 1.25A 200 0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) GROUND CURRENT (A) 10 0.1 400 1.25 Ground Current vs. Output Current 40 GROUND CURRENT (mA) 0.25 0.50 0.75 1.00 OUTPUT CURRENT (A) 600 GROUND CURRENT (mA) 200 800 GROUND CURRENT (mA) 300 Dropout Characteristics 6 Ground Current vs. Input Voltage 1000 GROUND CURRENT (A) 400 0 0.00 GROUND CURRENT (mA) 1000 GROUND CURRENT (mA) DROPOUT VOLTAGE (mV) 500 Dropout Voltage vs. Temperature OUTPUT VOLTAGE (V) Dropout Voltage vs. Output Current 800 RLOAD = 100 600 400 200 0 -200 -30 -20 -10 0 10 20 INPUT VOLTAGE (V) 30 M9999-071307 Micrel, Inc. MIC2940A/2941A Typical Characteristics (continued) 50 VE N = 2V 25 0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) MIC29402/3 Adjust Pin Current vs. Temperature OUTPUT (mV) 40 30 OUTPUT (mV) 0 5 TIME (ms) 10 100 COUT = 10 F 20 0 -20 -200 2.0 1.5 1.0 5mA 0.5 0.0 -0.5 -5 0 -60 -30 0 30 60 90 120 150 TEMPERATURE (C) INPUT (V) 8 6 4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 TIME (ms) 10 Line Transient COUT = 100 F 0 8 6 4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 TIME (ms) 1 0.1 1x106 1x100 0.01 100x103 ILOAD = 10mA 10x103 OUTPUT IMPEDANCE ( ) 10 10 Output Impedance vs. Frequency 1x103 ILOAD = 5mA 20 0 5 TIME (ms) 10 -10 100x100 10 COUT = 100 F 0 10 -40 20 Load Transient -100 Line Transient 40 10x100 ADJUST PIN CURRENT (nA) 50 -500 2.0 1.5 1.0 5mA 0.5 0.0 -0.5 -5 OUTPUT (A) 75 COUT = 10 F 200 OUTPUT (mV) VE N = 5V OUTPUT (mV) 100 Load Transient 750 500 250 0 -250 INPUT (V) ENABLE CURRENT (A) 125 OUTPUT (A) MIC29401/2 Shutdown Current vs. Temperature FREQUENCY (Hz) July 2007 6 M9999-071307 Micrel, Inc. MIC2940A/2941A Reducing Output Noise In reference applications it may be advantageous to reduce the AC noise present at the output. One method is to reduce the regulator bandwidth by increasing the size of the output capacitor. This is relatively inefficient, as increasing the capacitor from 1F to 220F only decreases the noise from 430V to 160VRMS for a 100kHz bandwidth at 5V output. Noise can be reduced by a factor of four with the MIC2941A by adding a bypass capacitor across R1. Pick Application Information External Capacitors A 10F (or greater) capacitor is required between the MIC2940A output and ground to prevent oscillations due to instability. Most types of tantalum or aluminum electrolytics will be adequate; film types will work, but are costly and therefore not recommended. Many aluminum electrolytics have electrolytes that freeze at about -30C, so solid tantalums are recommended for operation below -25C. The important parameters of the capacitor are an effective series resistance of about 5 or less and a resonant frequency above 500kHz. The value of this capacitor may be increased without limit. At lower values of output current, less output capacitance is required for output stability. The capacitor can be reduced to 3.3F for current below 100mA or 2.2F for currents below 10mA. Adjusting the MIC2941A to voltages below 5V runs the error amplifier at lower gains so that more output capacitance is needed. For the worst-case situation of a 1.25A load at 1.23V output (Output shorted to Adjust) a 22F (or greater) capacitor should be used. The MIC2940A will remain stable and in regulation with load currents ranging from 5mA on up to the full 1.25A rating. The external resistors of the MIC2941A version may be scaled to draw this minimum load current. A 0.22F capacitor should be placed from the MIC2940A input to ground if there is more than 10 inches of wire between the input and the AC filter capacitor or if a battery is used as the input. C BYPASS or about 0.01F. When doing this, the output capacitor must be increased to 22F to maintain stability. These changes reduce the output noise from 430V to 100VRMS for a 100kHz bandwidth at 5V output. With the bypass capacitor added, noise no longer scales with output voltage so that improvements are more dramatic at higher output voltages. Automotive Applications The MIC2940A is ideally suited for automotive applications for a variety of reasons. It will operate over a wide range of input voltages with very low dropout voltages (40mV at light loads), and very low quiescent currents (240A typical). These features are necessary for use in battery powered systems, such as automobiles. It is a "bulletproof" device with the ability to survive both reverse battery (negative transients up to 20V below ground), and load dump (positive transients up to 60V) conditions. A wide operating temperature range with low temperature coefficients is yet another reason to use these versatile regulators in automotive designs. Programming the Output Voltage (MIC2941A) The MIC2941A may be programmed for any output voltage between its 1.235V reference and its 26V maximum rating. An external pair of resistors is required, as shown in Figure 3. VOUT = VREF x { 1 + R1/R2 } - |IFB| R1 where VREF is the nominal 1.235 reference voltage and IFB is the Adjust pin bias current, nominally 20nA. The minimum recommended load current of 1A forces an upper limit of 1.2M on the value of R2, if the regulator must work with no load (a condition often found in CMOS in standby), IFB will produce a -2% typical error in VOUT which may be eliminated at room temperature by trimming R1. For better accuracy, choosing R2 = 100k reduces this error to 0.17% while increasing the resistor program current to 12A. Since the MIC2941A typically draws 100A at no load with SHUTDOWN opencircuited, this is a negligible addition. July 2007 1 2R 1 200Hz 4.75V OUTPUT VOLTAGE ERROR NOT * VALID NOT * VALID INPUT VOLTAGE 5V 1.3V Figure 1. ERROR Output Timing 7 M9999-071307 Micrel, Inc. MIC2940A/2941A Typical Applications V IN +VIN VIN +VIN VOUT = 5V V OUT + VOUT S HUTDOWN INPUT 10F SHUTDOWN OFF GND AD JU S T 26V 1.2V V OUT R1 100 pF 22F ON 1.23V GND V OUT = V R E F x (1 + R1 ) R2 +5V to +7V +V IN +V IN V IN VOUT SHUTDOWN INPUT V OUT = V IN V CC OUT VOUT SHUTDOWN OFF + ON 100pF ADJ GND 5V ADJUST 3.3V 470 k 220k 1% 300k 10F 1% 180k 1% 2N2222 Adjust Pin Low = Enable Output. Q1 ON = 3.3V, Q1 OFF = 5.0V. * Minimum Input-Output Voltage Ranges from 40mV to 400mV, depending on Load Current. Figure 5. MIC2941A 5.0V or 3.3V Selectable Regulator with Shutdown Figure 4. MIC2941A Wide Input Voltage Range Current Limit July 2007 R2 Figure 3. MIC2941A Adjustable Regulator Figure 2. MIC2940A-5.0 Fixed +5V Regulator GND VREF 8 M9999-071307 Micrel, Inc. MIC2940A/2941A Package Information 3-Pin TO-220 (T) 3-Pin TO-263 (U) July 2007 9 M9999-071307 Micrel, Inc. MIC2940A/2941A 5-Pin TO-220 (T) 5-Pin TO-263 (U) July 2007 10 M9999-071307 Micrel, Inc. MIC2940A/2941A MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. (c) 2004 Micrel, Incorporated. July 2007 11 M9999-071307