LM2931CT

LM2931 Series Low Dropout Regulators June 2005 LM2931 Series Low Dropout Regulators General Description The LM2931 positive voltage regulator features a very low quiescent current of 1mA or less when supplying 10mA loads. This unique characteristic and the extremely low input-output differential required for proper regulation (0.2V for output currents of 10mA) make the LM2931 the ideal regulator for standby power systems. Applications include memory standby circuits, CMOS and other low power processor power supplies as well as systems demanding as much as 100mA of output current. Designed originally for automotive applications, the LM2931 and all regulated circuitry are protected from reverse battery installations or 2 battery jumps. During line transients, such as a load dump (60V) when the input voltage to the regulator can momentarily exceed the specified maximum operating voltage, the regulator will automatically shut down to protect both internal circuits and the load. The LM2931 cannot be harmed by temporary mirror-image insertion. Familiar regulator features such as short circuit and thermal overload protection are also provided. The LM2931 family includes a fixed 5V output (±3.8% tolerance for A grade) or an adjustable output with ON/OFF pin. Both versions are available in a TO-220 power package, TO-263 surface mount package, and an 8-lead surface mount package. The fixed output version is also available in the TO-92 plastic and 6-Bump micro SMD packages. Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Very low quiescent current Output current in excess of 100 mA Input-output differential less than 0.6V Reverse battery protection 60V load dump protection −50V reverse transient protection Short circuit protection Internal thermal overload protection Mirror-image insertion protection Available in TO-220, TO-92, TO-263, SO-8 or 6-Bump micro SMD packages ■ Available as adjustable with TTL compatible switch ■ See AN-1112 for micro SMD considerations Connection Diagrams FIXED VOLTAGE OUTPUT TO-220 3-Lead Power Package TO-263 Surface-Mount Package 525406 Front View 525411 Top View 525412 Side View 8-Pin Surface Mount TO-92 Plastic Package 525408 Bottom View 525407 *NC = Not internally connected. Must be electrically isolated from the rest of the circuit for the micro SMD package. Top View © 2006 National Semiconductor Corporation 5254 www.national.com LM2931 6-Bump micro SMD micro SMD Laser Mark 525439 525438 Top View (Bump Side Down) ADJUSTABLE OUTPUT VOLTAGE TO-220 5-Lead Power Package TO-263 5-Lead Surface-Mount Package 525409 Front View 525413 Top View 525414 Side View 8-Pin Surface Mount 525410 Top View www.national.com 2 LM2931 Ordering Information Output Number 5V Package 3-Pin TO-220 3-Pin TO-263 TO-92 8-Pin SOIC * 6-Bump micro SMD Adjustable, 3V to 24V 5-Pin TO-220 5-Pin TO-263 8-Pin SOIC 3.3V Note: * 6-Bump micro SMD Part Number LM2931T-5.0 LM2931AT-5.0 LM2931S-5.0 LM2931AS-5.0 LM2931Z-5.0 LM2931AZ-5.0 LM2931M-5.0 LM2931AM-5.0 LM2931IBPX-5.0 LM2931CT LM2931CS LM2931CM LM2931IBPX-3.3 Package Marking LM2931T-5.0 LM2931AT-5.0 LM2931S-5.0 LM2931AS-5.0 LM2931Z-5 LM2931AZ 2931M-5.0 2931AM-5.0 ‐ LM2931CT LM2931CS LM2931CM ‐ Transport Media Rails Rails Rails Rails 1.8k Units per Box 1.8k Units per Box Rails Rails Tape and Reel Rails Rails Rails Tape and Reel BPA06HTA T05A TS5B M08A BPA06HTB M08A Z03A TS3B NSC Drawing T03B The micro SMD package marking is a single digit manufacturing Date Code Only. 3 www.national.com LM2931 Typical Applications LM2931 Fixed Output 525404 *Required if regulator is located far from power supply filter. **C2 must be at least 100 μF to maintain stability. May be increased without bound to maintain regulation during transients. Locate as close as possible to the regulator. This capacitor must be rated over the same operating temperature range as the regulator. The equivalent series resistance (ESR) of this capacitor is critical; see curve. LM2931 Adjustable Output 525405 Note: Using 27k for R1 will automatically compensate for errors in VOUT due to the input bias current of the ADJ pin (approximately 1 μA). www.national.com 4 LM2931 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Voltage  Operating Range  Overvoltage Protection   LM2931A, LM2931C (Adjustable) 60V 26V   LM2931 Internal Power Dissipation  (Notes 2, 4) Operating Ambient Temperature  Range Maximum Junction Temperature Storage Temperature Range Lead Temp. (Soldering, 10 seconds) ESD Tolerance (Note 5) 50V Internally Limited −40°C to +85°C 125°C −65°C to +150°C 230°C 2000V Electrical Characteristics for Fixed 3.3V Version VIN = 14V, IO = 10mA, TJ = 25°C, C2 = 100μF (unless otherwise specified) (Note 2) Parameter Conditions Typ Output Voltage 3.3 LM2931-3.3 Limit (Note 3) 3.465 3.135 3.630 2.970 4 10 200 0.4 1.0 33 50 VMAX VMIN VMAX VMIN mVMAX mVMAX mΩ mAMAX Units 4V ≤ VIN ≤ 26V, IO = 100 mA −40°C ≤ TJ ≤ 125°C Line Regulation Load Regulation Output Impedance Quiescent Current 4V ≤ VIN ≤ 26V 5mA ≤ IO ≤ 100mA 100mADC and 10mArms, 100Hz - 10kHz IO ≤ 10mA, 4V ≤ VIN ≤ 26V −40°C ≤ TJ ≤ 125°C IO = 100mA, VIN = 14V, TJ = 25°C Output Noise Voltage Long Term Stability Ripple Rejection Dropout Voltage fO = 120Hz IO = 10mA IO = 100mA Maximum Operational Input Voltage Maximum Line Transient RL = 500Ω, VO ≤ 5.5V, T = 1ms, τ ≤ 100ms Reverse Polarity Input Voltage, DC VO ≥ −0.3V, RL = 500Ω Reverse Polarity Input Voltage, Transient T = 1ms, τ ≤ 100ms, RL = 500Ω −30 −80 10Hz -100kHz, COUT = 100μF 15 330 13 80 0.05 0.30 33 70 mA μVrms mV/1000 hr dB 0.2 0.6 26 50 VMAX VMIN VMIN VMIN VMIN −15 −50 5 www.national.com LM2931 Electrical Characteristics for Fixed 5V Version VIN = 14V, IO = 10mA, TJ = 25°C, C2 = 100 μF (unless otherwise specified) (Note 2) Parameter Conditions LM2931A-5.0 Typ Output Voltage 5 Limit (Note 3) 5.19 4.81 5.25 4.75 2 4 14 200 0.4 1.0 10 30 50 2 4 14 200 0.4 1.0 LM2931-5.0 Typ 5 Limit (Note 3) 5.25 4.75 5.5 4.5 10 30 50 VMAX VMIN VMAX VMIN mVMAX mVMAX mΩ mAMAX Units 6.0V ≤ VIN ≤ 26V, IO = 100mA −40°C ≤ TJ ≤ 125°C Line Regulation 9V ≤ VIN ≤ 16V 6V ≤ VIN ≤ 26V Load Regulation Output Impedance Quiescent Current 5 mA ≤ IO ≤ 100mA 100mADC and 10mArms, 100Hz -10kHz IO ≤ 10mA, 6V ≤ VIN ≤ 26V −40°C ≤ TJ ≤ 125°C IO = 100mA, VIN = 14V, TJ = 25°C Output Noise Voltage Long Term Stability Ripple Rejection Dropout Voltage fO = 120 Hz IO = 10mA IO = 100mA Maximum Operational Input Voltage Maximum Line Transient RL = 500Ω, VO ≤ 5.5V, T = 1ms, τ ≤ 100ms Reverse Polarity Input Voltage, VO ≥ −0.3V, RL = 500Ω DC Reverse Polarity Input Voltage, T = 1ms, τ ≤ 100ms, RL = 500Ω Transient 10Hz -100kHz, COUT = 100μF 15 30 5 15 mAMAX mAMIN μVrms mV/1000 hr dBMIN 0.2 0.6 26 VMAX VMIN 500 20 80 0.05 0.3 33 55 0.2 0.6 26 500 20 80 0.05 0.3 33 70 −30 −80 60 −15 −50 70 −30 −80 50 −15 −50 VMIN VMIN VMIN Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device beyond its rated operating conditions. Note 2: See circuit in Typical Applications. To ensure constant junction temperature, low duty cycle pulse testing is used. Note 3: All limits are guaranteed for TJ = 25°C (standard type face) or over the full operating junction temperature range of −40°C to +125°C (bold type face). Note 4: The maximum power dissipation is a function of maximum junction temperature TJmax, total thermal resistance θJA, and ambient temperature TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJmax − TA)/θJA. If this dissipation is exceeded, the die temperature will rise above 150°C and the LM2931 will go into thermal shutdown. For the LM2931 in the TO-92 package, θJA is 195°C/W; in the SO-8 package, θJA is 160°C/W, and in the TO-220 package, θJA is 50°C/W; in the TO-263 package, θJA is 73°C/W; and in the 6-Bump micro SMD package θJA is 290°C/W. If the TO-220 package is used with a heat sink, θJA is the sum of the package thermal resistance junction-to-case of 3°C/W and the thermal resistance added by the heat sink and thermal interface. If the TO-263 package is used, the thermal resistance can be reduced by increasing the P.C. board copper area thermally connected to the package: Using 0.5 square inches of copper area, θJA is 50°C/W; with 1 square inch of copper area, θJA is 37°C/W; and with 1.6 or more square inches of copper area, θJA is 32°C/ W. www.national.com 6 LM2931 Note 5: Human body model, 100 pF discharged through 1.5 kΩ. Electrical Characteristics for Adjustable Version VIN = 14V, VOUT = 3V, IO = 10 mA, TJ = 25°C, R1 = 27k, C2 = 100 μF (unless otherwise specified) (Note 2) Parameter Reference Voltage Conditions Typ 1.20 Limit 1.26 1.14 IO ≤ 100 mA, −40°C ≤ Tj ≤ 125°C, R1 = 27k Measured from VOUT to Adjust Pin Output Voltage Range 1.32 1.08 24 3 Line Regulation Load Regulation Output Impedance Quiescent Current VOUT + 0.6V ≤ VIN ≤ 26V 5 mA ≤ IO ≤ 100 mA 100 mADC and 10 mArms, 100 Hz–10 kHz IO = 10 mA IO = 100 mA During Shutdown RL = 500Ω Output Noise Voltage Long Term Stability Ripple Rejection Dropout Voltage fO = 120 Hz IO ≤ 10 mA IO = 100 mA Maximum Operational Input Voltage Maximum Line Transient IO = 10 mA, Reference Voltage ≤ 1.5V T = 1 ms, τ ≤ 100 ms Reverse Polarity Input Voltage, DC Reverse Polarity Input Voltage, Transient On/Off Threshold Voltage  On  Off On/Off Threshold Current VO=3V 2.0 2.2 20 1.2 3.25 50 VMAX VMIN μAMAX T = 1 ms, τ ≤ 100 ms, RL = 500Ω −80 −50 VMIN VO ≥ −0.3V, RL = 500Ω −30 −15 VMIN 10 Hz–100 kHz 0.2 0.3 40 0.4 15 0.8 100 0.4 0.02 0.05 0.3 33 70 0.2 0.6 26 60 1 1 1.5 1 Units Limit VMAX VMIN VMAX VMIN VMAX VMIN mV/VMAX %MAX mΩ/V mAMAX mA mAMAX μVrms/V %/1000 hr %/V VMAX VMAX VMIN VMIN 7 www.national.com LM2931 Typical Performance Characteristics Dropout Voltage Dropout Voltage 525416 525417 Low Voltage Behavior Output at Voltage Extremes 525418 525419 Line Transient Response Load Transient Response 525420 525421 www.national.com 8 LM2931 Peak Output Current Quiescent Current 525422 525423 Quiescent Current Quiescent Current 525424 525425 Ripple Rejection Ripple Rejection 525426 525427 9 www.national.com LM2931 Output Impedance Operation During Load Dump 525428 525429 Reference Voltage Maximum Power Dissipation (SO-8) 525430 525431 Maximum Power Dissipation (TO-220) Maximum Power Dissipation (TO-92) 525432 525433 www.national.com 10 LM2931 Maximum Power Dissipation (TO-263) (Note 4) On/Off Threshold 525435 525434 Output Capacitor ESR 525436 11 www.national.com LM2931 Schematic Diagram 525401 www.national.com 12 LM2931 Application Hints One of the distinguishing factors of the LM2931 series regulators is the requirement of an output capacitor for device stability. The value required varies greatly depending upon the application circuit and other factors. Thus some comments on the characteristics of both capacitors and the regulator are in order. High frequency characteristics of electrolytic capacitors depend greatly on the type and even the manufacturer. As a result, a value of capacitance that works well with the LM2931 for one brand or type may not necessary be sufficient with an electrolytic of different origin. Sometimes actual bench testing, as described later, will be the only means to determine the proper capacitor type and value. Experience has shown that, as a rule of thumb, the more expensive and higher quality electrolytics generally allow a smaller value for regulator stability. As an example, while a high-quality 100 μF aluminum electrolytic covers all general application circuits, similar stability can be obtained with a tantalum electrolytic of only 47μF. This factor of two can generally be applied to any special application circuit also. Another critical characteristic of electrolytics is their performance over temperature. While the LM2931 is designed to operate to −40°C, the same is not always true with all electrolytics (hot is generally not a problem). The electrolyte in many aluminum types will freeze around −30°C, reducing their effective value to zero. Since the capacitance is needed for regulator stability, the natural result is oscillation (and lots of it) at the regulator output. For all application circuits where cold operation is necessary, the output capacitor must be rated to operate at the minimum temperature. By coincidence, worst-case stability for the LM2931 also occurs at minimum temperatures. As a result, in applications where the regulator junction temperature will never be less than 25°C, the output capacitor can be reduced approximately by a factor of two over the value needed for the entire temperature range. To continue our example with the tantalum electrolytic, a value of only 22μF would probably thus suffice. For high-quality aluminum, 47μF would be adequate in such an application. Another regulator characteristic that is noteworthy is that stability decreases with higher output currents. This sensible fact has important connotations. In many applications, the LM2931 is operated at only a few milliamps of output current or less. In such a circuit, the output capacitor can be further reduced in value. As a rough estimation, a circuit that is required to deliver a maximum of 10mA of output current from the regulator would need an output capacitor of only half the value compared to the same regulator required to deliver the full output current of 100mA. If the example of the tantalum capacitor in the circuit rated at 25°C junction temperature and above were continued to include a maximum of 10mA of output current, then the 22μF output capacitor could be reduced to only 10μF. In the case of the LM2931CT adjustable regulator, the minimum value of output capacitance is a function of the output voltage. As a general rule, the value decreases with higher output voltages, since internal loop gain is reduced. At this point, the procedure for bench testing the minimum value of an output capacitor in a special application circuit should be clear. Since worst-case occurs at minimum operating temperatures and maximum operating currents, the entire circuit, including the electrolytic, should be cooled to the minimum temperature. The input voltage to the regulator should be maintained at 0.6V above the output to keep internal power dissipation and die heating to a minimum. Worstcase occurs just after input power is applied and before the die has had a chance to heat up. Once the minimum value of capacitance has been found for the brand and type of electrolytic in question, the value should be doubled for actual use to account for production variations both in the capacitor and the regulator. (All the values in this section and the remainder of the data sheet were determined in this fashion.) LM2931 micro SMD Light Sensitivity When the LM2931 micro SMD package is exposed to bright sunlight, normal office fluorescent light, and other LED's, it operates within the guaranteed limits specified in the electrical characteristic table. Definition of Terms Dropout Voltage: The input-output voltage differential at which the circuit ceases to regulate against further reduction in input voltage. Measured when the output voltage has dropped 100 mV from the nominal value obtained at 14V input, dropout voltage is dependent upon load current and junction temperature. Input Voltage: The DC voltage applied to the input terminals with respect to ground. Input-Output Differential: The voltage difference between the unregulated input voltage and the regulated output voltage for which the regulator will operate. Line Regulation: The change in output voltage for a change in the input voltage. The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected. Load Regulation: The change in output voltage for a change in load current at constant chip temperature. Long Term Stability: Output voltage stability under accelerated life-test conditions after 1000 hours with maximum rated voltage and junction temperature. Output Noise Voltage: The rms AC voltage at the output, with constant load and no input ripple, measured over a specified frequency range. Quiescent Current: That part of the positive input current that does not contribute to the positive load current. The regulator ground lead current. Ripple Rejection: The ratio of the peak-to-peak input ripple voltage to the peak-to-peak output ripple voltage at a specified frequency. Temperature Stability of VO: The percentage change in output voltage for a thermal variation from room temperature to either temperature extreme. 13 www.national.com LM2931 Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead Surface Mount Package (M) NS Package Number M08A 3-Lead TO-220 Plastic Package (T) NS Package Number T03B www.national.com 14 LM2931 5-Lead TO-220 Power Package (T) NS Package Number T05A 3-Lead TO-263 Surface Mount Package NS Package Number TS3B 15 www.national.com LM2931 5-Lead TO-263 Surface Mount Package NS Package Number TS5B 3-Lead TO-92 Plastic Package (Z) NS Package Number Z03A www.national.com 16 LM2931 NOTE: UNLESS OTHERWISE SPECIFIED. 1. EPOXY COATING. 2. 63Sn/37Pb EUTECTIC BUMP. 3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD. 4. PIN A1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEST ORIENTATION PINS ARE NUMBERED COUNTERCLOCKWISE. 5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS PACKAGE HEIGHT. 6. REFERENCE JEDEC REGISTRATION MO-211, VARIATION BC. 6-Bump micro SMD NS Package Number BPA06HTB X1 = 0.955 X2 = 1.717 X3 = 0.850 17 www.national.com LM2931 Series Low Dropout Regulators Notes National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at www.national.com. LIFE SUPPORT POLICY NATIONAL'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, 2. (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no "Banned Substances" as defined in CSP-9-111S2. Leadfree products are RoHS compliant. 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