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 n Available as adjustable with TTL compatible switch n See AN-1112 for micro SMD considerations n n n n n n n n n n Connection Diagrams FIXED VOLTAGE OUTPUT TO-220 3-Lead Power Package TO-263 Surface-Mount Package 00525406 00525411 Front View Top View 00525412 Side View 8-Pin Surface Mount TO-92 Plastic Package 00525408 Bottom View 00525407 Top View *NC = Not internally connected. Must be electrically isolated from the rest of the circuit for the micro SMD package. © 2002 National Semiconductor Corporation DS005254 www.national.com LM2931 Series Low Dropout Regulators March 2002 LM2931 Connection Diagrams (Continued) 6-Bump micro SMD micro SMD Laser Mark 00525439 00525438 Top View (Bump Side Down) ADJUSTABLE OUTPUT VOLTAGE TO-220 5-Lead Power Package TO-263 5-Lead Surface-Mount Package 00525409 00525413 Front View Top View 00525414 Side View 8-Pin Surface Mount 00525410 Top View www.national.com 2 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 3.3V 5-Pin TO-220 Part Number Package Marking Transport Media NSC Drawing T03B LM2931T-5.0 LM2931T-5.0 Rails LM2931AT-5.0 LM2931AT-5.0 Rails LM2931S-5.0 LM2931S-5.0 Rails LM2931AS-5.0 LM2931AS-5.0 Rails LM2931Z-5.0 LM2931Z-5 1.8k Units per Box LM2931AZ-5.0 LM2931AZ 1.8k Units per Box TS3B Z03A LM2931M-5.0 2931M-5.0 Rails LM2931AM-5.0 2931AM-5.0 Rails M08A LM2931IBPX-5.0 - Tape and Reel BPA06HTA LM2931CT LM2931CT Rails T05A 5-Pin TO-263 LM2931CS LM2931CS Rails TS5B 8-Pin SOIC LM2931CM LM2931CM Rails M08A LM2931IBPX-3.3 - Tape and Reel BPA06HTB * 6-Bump micro SMD Note: The micro SMD package marking is a single digit manufacturing Date Code Only. 3 www.national.com LM2931 Ordering Information LM2931 Typical Applications LM2931 Fixed Output 00525404 *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 00525405 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 Internal Power Dissipation (Note 1) (Note 2) (Note 4) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Internally Limited Operating Ambient Temperature Range Input Voltage −40˚C to +85˚C Maximum Junction Temperature Operating Range 26V Storage Temperature Range Overvoltage Protection LM2931A, LM2931C (Adjustable) 125˚C −65˚C to +150˚C Lead Temp. (Soldering, 10 seconds) 230˚C ESD Tolerance (Note 5) 2000V 60V LM2931 50V Electrical Characteristics for Fixed 3.3V Version VIN = 14V, IO = 10mA, TJ = 25˚C, C2 = 100µF (unless otherwise specified) (Note 2) Parameter Conditions LM2931-3.3 Output Voltage Limit (Note 3) 3.3 3.465 3.135 VMAX VMIN 3.630 2.970 VMAX VMIN 4 33 mVMAX 50 mVMAX 4V ≤ VIN ≤ 26V, IO = 100 mA −40˚C ≤ TJ ≤ 125˚C Line Regulation 4V ≤ VIN ≤ 26V Load Regulation 5mA ≤ IO ≤ 100mA 10 Output Impedance 100mADC and 10mArms, 100Hz - 10kHz 200 IO ≤ 10mA, 4V ≤ VIN ≤ 26V 0.4 Quiescent Current Units Typ mΩ 1.0 mAMAX −40˚C ≤ TJ ≤ 125˚C Output Noise Voltage IO = 100mA, VIN = 14V, TJ = 25˚C 15 mA 10Hz -100kHz, COUT = 100µF 330 µVrms 13 mV/1000 hr Long Term Stability Ripple Rejection fO = 120Hz 80 Dropout Voltage IO = 10mA IO = 100mA 0.05 0.30 0.2 0.6 VMAX 33 26 VMIN Maximum Operational Input Voltage dB Maximum Line Transient RL = 500Ω, VO ≤ 5.5V, T = 1ms, τ ≤ 100ms 70 50 VMIN Reverse Polarity Input Voltage, DC VO ≥ −0.3V, RL = 500Ω −30 −15 VMIN Reverse Polarity Input Voltage, Transient T = 1ms, τ ≤ 100ms, RL = 500Ω −80 −50 VMIN 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 6.0V ≤ VIN ≤ 26V, IO = 100mA −40˚C ≤ TJ ≤ 125˚C Line Regulation Limit (Note 3) 5.19 4.81 LM2931-5.0 Typ 5 5.25 4.75 9V ≤ VIN ≤ 16V 6V ≤ VIN ≤ 26V 2 4 5 10 30 2 4 Units Limit (Note 3) 5.25 4.75 VMAX VMIN 5.5 4.5 VMAX VMIN 10 30 mVMAX www.national.com LM2931 Absolute Maximum Ratings LM2931 Electrical Characteristics for Fixed 5V Version (Continued) VIN = 14V, IO = 10mA, TJ = 25˚C, C2 = 100 µF (unless otherwise specified) (Note 2) Parameter Conditions LM2931A-5.0 LM2931-5.0 Typ Limit (Note 3) 50 Units Typ Limit (Note 3) 14 50 Load Regulation 5 mA ≤ IO ≤ 100mA 14 Output Impedance 100mADC and 10mArms, 100Hz -10kHz 200 IO ≤ 10mA, 6V ≤ VIN ≤ 26V 0.4 1.0 0.4 IO = 100mA, VIN = 14V, TJ = 25˚C 15 30 5 15 10Hz -100kHz, COUT = 100µF 500 500 µVrms 20 20 mV/1000 hr dBMIN Quiescent Current 200 mVMAX mΩ 1.0 mAMAX −40˚C ≤ TJ ≤ 125˚C Output Noise Voltage Long Term Stability mAMAX mAMIN Ripple Rejection fO = 120 Hz 80 55 80 Dropout Voltage IO = 10mA IO = 100mA 0.05 0.3 0.2 0.6 0.05 0.3 0.2 0.6 VMAX 33 26 33 26 VMIN Maximum Operational Input Voltage Maximum Line Transient RL = 500Ω, VO ≤ 5.5V, T = 1ms, τ ≤ 100ms 70 60 70 50 VMIN Reverse Polarity Input Voltage, DC VO ≥ −0.3V, RL = 500Ω −30 −15 −30 −15 VMIN Reverse Polarity Input Voltage, Transient T = 1ms, τ ≤ 100ms, RL = 500Ω −80 −50 −80 −50 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. 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 Conditions Typ Limit 1.20 1.26 Units Limit Reference Voltage VMAX 1.14 VMIN IO ≤ 100 mA, −40˚C ≤ Tj ≤ 125˚C, R1 = 27k 1.32 VMAX Measured from VOUT to Adjust Pin 1.08 VMIN 24 VMAX Output Voltage Range 3 VMIN Line Regulation VOUT + 0.6V ≤ VIN ≤ 26V 0.2 1.5 mV/VMAX Load Regulation 5 mA ≤ IO ≤ 100 mA 0.3 1 %MAX Output Impedance 100 mADC and 10 mArms, 100 Hz–10 kHz 40 Quiescent Current IO = 10 mA 0.4 1 mAMAX IO = 100 mA 15 During Shutdown RL = 500Ω 0.8 www.national.com 6 mΩ/V mA 1 mAMAX LM2931 Electrical Characteristics for Adjustable Version (Continued) VIN = 14V, VOUT = 3V, IO = 10 mA, TJ = 25˚C, R1 = 27k, C2 = 100 µF (unless otherwise specified) (Note 2) Parameter Conditions Typ Limit Units Limit Output Noise Voltage 10 Hz–100 kHz Long Term Stability 100 µVrms/V 0.4 %/1000 hr Ripple Rejection fO = 120 Hz 0.02 Dropout Voltage IO ≤ 10 mA 0.05 0.2 VMAX IO = 100 mA 0.3 0.6 VMAX 33 26 VMIN 70 60 VMIN −30 −15 VMIN −80 −50 VMIN On 2.0 1.2 VMAX Off 2.2 3.25 VMIN 20 50 µAMAX %/V Maximum Operational Input Voltage Maximum Line Transient IO = 10 mA, Reference Voltage ≤ 1.5V Reverse Polarity Input VO ≥ −0.3V, RL = 500Ω T = 1 ms, τ ≤ 100 ms Voltage, DC Reverse Polarity Input T = 1 ms, τ ≤ 100 ms, RL = 500Ω Voltage, Transient On/Off Threshold Voltage VO =3V On/Off Threshold Current 7 www.national.com LM2931 Typical Performance Characteristics Dropout Voltage Dropout Voltage 00525417 00525416 Low Voltage Behavior Output at Voltage Extremes 00525418 00525419 Line Transient Response Load Transient Response 00525420 www.national.com 00525421 8 LM2931 Typical Performance Characteristics (Continued) Peak Output Current Quiescent Current 00525423 00525422 Quiescent Current Quiescent Current 00525424 00525425 Ripple Rejection Ripple Rejection 00525426 00525427 9 www.national.com LM2931 Typical Performance Characteristics (Continued) Operation During Load Dump Output Impedance 00525428 00525429 Maximum Power Dissipation (SO-8) Reference Voltage 00525430 00525431 Maximum Power Dissipation (TO-220) Maximum Power Dissipation (TO-92) 00525432 www.national.com 00525433 10 LM2931 Typical Performance Characteristics (Continued) Maximum Power Dissipation (TO-263) (Note 4) On/Off Threshold 00525434 00525435 Output Capacitor ESR 00525436 11 www.national.com LM2931 Schematic Diagram 00525401 www.national.com 12 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. 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 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. Worst-case 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. Application Hints 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 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 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 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 5-Lead TO-263 Surface Mount Package NS Package Number TS5B www.national.com 16 LM2931 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 3-Lead TO-92 Plastic Package (Z) NS Package Number Z03A 17 www.national.com LM2931 Series Low Dropout Regulators Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 6-Bump micro SMD NS Package Number BPA06HTB X1 = 0.955 X2 = 1.717 X3 = 0.850 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. 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, (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. National Semiconductor Corporation Americas Email: [email protected] www.national.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 2. 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. National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: [email protected] National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 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.