LM4051 Precision Micropower Shunt Voltage Reference General Description j Low output noise Ideal for space critical applications, the LM4051 precision voltage reference is available in the sub-miniature (3 mm x 1.3 mm) SOT-23 surface-mount package. The LM4051’s advanced design eliminates the need for an external stabilizing capacitor while ensuring stability with any capacitive load, thus making the LM4051 easy to use. Further reducing design effort is the availability of a fixed (1.225V) and adjustable reverse breakdown voltage. The minimum operating current is 60 µA for the LM4051-1.2 and the LM4051-ADJ. Both versions have a maximum operating current of 12 mA. The LM4051 comes in three grades (A, B, and C). The best grade devices (A) have an initial accuracy of 0.1%, while the B-grade have 0.2% and the C-grade 0.5%, all with a tempco of 50 ppm/˚C guaranteed from −40˚C to 125˚C. The LM4051 utilizes fuse and zener-zap trim of reference voltage during wafer sort to ensure that the prime parts have an accuracy of better than ± 0.1% (A grade) at 25˚C. Features n n n n Small packages: SOT-23 No output capacitor required Tolerates capacitive loads Reverse breakdown voltage options of 1.225V and adjustable (10 Hz to 10kHz) 20µVrms j Wide operating current range j Industrial temperature range 60µA to 12mA −40˚C to +85˚C j Extended temperature range −40˚C to +125˚C j Low temperature coefficient 50 ppm/˚C (max) Applications n n n n n n n n n n n Portable, Battery-Powered Equipment Data Acquisition Systems Instrumentation Process Control Energy Management Automotive and Industrial Precision Audio Components Base Stations Battery Chargers Medical Equipment Communication Key Specifications (LM4051-1.2) j Output voltage tolerance ± 0.1%(max) (A grade, 25˚C) Connection Diagrams SOT-23 10122201 10122240 *This pin must be left floating or connected to pin 2. Top View See NS Package Number MF03A © 2005 National Semiconductor Corporation DS101222 www.national.com LM4051 Precision Micropower Shunt Voltage Reference March 2005 LM4051 Ordering Information Industrial Temperature Range (−40˚C to +85˚C) Reverse Breakdown Voltage Tolerance at 25˚C and Average Reverse Breakdown Voltage Temperature Coefficient ± 0.1%, 50 ppm/˚C max (A grade) ± 0.2%, 50 ppm/˚C max (B grade) ± 0.5%, 50 ppm/˚C max (C grade) LM4051 Supplied as 1000 Units, Tape and Reel LM4051 Supplied as 3000 Units, Tape and Reel LM4051AIM3-1.2 LM4051AIM3X-1.2 LM4051AIM3-ADJ LM4051AIM3X-ADJ LM4051BIM3-1.2 LM4051BIM3X-1.2 LM4051BIM3-ADJ LM4051BIM3X-ADJ LM4051CIM3-1.2 LM4051CIM3X-1.2 LM4051CIM3-ADJ LM4051CIM3X-ADJ Extended Temperature Range (−40˚C to +125˚C) Reverse Breakdown Voltage Tolerance at 25˚C and Average Reverse Breakdown Voltage Temperature Coefficient ± 0.1%, 50 ppm/˚C max (A grade) ± 0.2%, 50 ppm/˚C max (B grade) ± 0.5%, 50 ppm/˚C max (C grade) LM4051 Supplied as 1000 Units, Tape and Reel LM4051 Supplied as 3000 Units, Tape and Reel LM4051AEM3-1.2 LM4051AEM3X-1.2 LM4051AEM3-ADJ LM4051AEM3X-ADJ LM4051BEM3-1.2 LM4051BEM3X-1.2 LM4051BEM3-ADJ LM4051BEM3X-ADJ LM4051CEM3-1.2 LM4051CEM3X-1.2 LM4051CEM3-ADJ LM4051CEM3X-ADJ SOT-23 Package Marking Information Only three fields of marking are possible on the SOT-23’s small surface. This table gives the meaning of the three fields. Part Marking RHA RIA RHB RIB RHC RIC Field Definition First Field: R = Reference Second Field: H = 1.225V Voltage Option I = Adjustable Third Field: A–C = Initial Reverse Breakdown Voltage or Reference Voltage Tolerance A = ± 0.1%, B = ± 0.2%, C = ± 0.5% www.national.com 2 If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Reverse Current 20 mA Forward Current 10 mA 2 kV Machine Model (Note 3) 200V See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” for other methods of soldering surface mount devices. Operating Ratings (Note 2) Maximum Output Voltage (LM4051-ADJ) 15V M3 Package 280 mW −65˚C to +150˚C Industrial Temperature Range −40˚C ≤ TA ≤ +85˚C Extended Temperature Range −40˚C ≤ TA ≤ +125˚C Reverse Current Lead Temperature M3 Packages Vapor phase (60 seconds) +215˚C Infrared (15 seconds) +220˚C (Tmin ≤ TA ≤ Tmax) Temperature Range Power Dissipation (TA = 25˚C) (Note 2) Storage Temperature Human Body Model (Note 3) LM4051-1.2 60 µA to 12 mA LM4051-ADJ 60 µA to 12 mA Output Voltage Range LM4051-ADJ ESD Susceptibility 1.24V to 10V LM4051-1.2 Electrical Characteristics Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25˚C. The grades A, B and C designate initial Reverse Breakdown Voltage tolerances of ± 0.1%, ± 0.2% and ± 0.5% respectively. Symbol VR IRMIN ∆VR/∆T ∆VR/∆IR Parameter Conditions LM4051AIM3 LM4051BIM3 LM4051CIM3 Typical LM4051AEM3 LM4051BEM3 LM4051CEM3 (Note 4) (Limits) (Limits) (Limts) (Note 5) (Note 5) (Note 5) 1.225 Units (Limit) Reverse Breakdown Voltage IR = 100 µA Reverse Breakdown Voltage Tolerance (Note 6) IR = 100 µA ± 1.2 ± 2.4 ±6 mV (max) Industrial Temp. Range ± 5.2 ± 6.4 ± 10.1 mV (max) Extended Temp. Range ± 7.4 ± 8.6 ± 12.2 mV (max) 60 60 60 µA (max) 65 65 65 µA (max) Minimum Operating Current Average Reverse Breakdown Voltage Temperature Coefficient (Note 6) Reverse Breakdown Voltage Change with Operating Current Change V 39 IR= 10 mA ± 20 IR = 1 mA ± 15 IR = 100 µA ∆T = −40˚C to 125˚C ± 15 IRMIN ≤ IR ≤ 1 mA 0.3 1 mA ≤ IR ≤ 12 mA µA ppm/˚C ppm/˚C ± 50 ± 50 ± 50 ppm/˚C (max) 1.1 1.1 1.1 mV (max) 1.5 1.5 1.5 mV (max) 6.0 6.0 6.0 mV (max) 8.0 8.0 8.0 mV (max) mV 1.8 mV ZR Reverse Dynamic Impedance IR = 1 mA, f = 120 Hz 0.5 Ω eN Wideband Noise IR = 100 µA 20 µVrms 10 Hz ≤ f ≤ 10 kHz ∆VR Reverse Breakdown Voltage Long Term Stability (Note 9) t = 1000 hrs T = 25˚C ± 0.1˚C IR = 100 µA 120 ppm VHYST Thermal Hysteresis (Note 10) ∆T = −40˚C to 125˚C 0.36 mV/V 3 www.national.com LM4051 Absolute Maximum Ratings (Note 1) LM4051 LM4051-ADJ (Adjustable) Electrical Characteristics Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TJ = 25˚C unless otherwise specified (SOT-23, see (Note 7) , IRMIN ≤ IR ≤ 12 mA, VREF ≤ VOUT ≤ 10V. The grades A, B and C designate initial Reference Voltage Tolerances of ± 0.1%, ± 0.2% and ± 0.5%, respectively for VOUT = 5V. Symbol VREF IRMIN ∆VREF/∆IR Parameter ∆VREF/∆T Typical LM4051AIM3 LM4051BIM3 LM4051CIM3 (Note 4) LM4051AEM3 LM4051BEM3 LM4051CEM3 (Limits) (Limits) (Limits) (Note 5) (Note 5) (Note 5) 1.212 Units (Limit) Reference Voltage IR = 100 µA, VOUT = 5V Reference Voltage Tolerance (Note 6), (Note 8) IR = 100 µA, VOUT = 5V ± 1.2 ± 2.4 ±6 mV (max) Industrial Temp. Range ± 5.2 ± 6.4 ± 10.1 mV (max) Extended Temp. Range ± 7.4 ± 8.6 ± 12.2 mV (max) 60 60 65 µA (max) Industrial Temp. Range 65 65 70 µA (max) Extended Temp. Range 70 70 75 µA (max) 1.1 1.1 1.1 mV(max) 1.5 1.5 1.5 mV(max) 6 6 6 mV (max) 8 8 8 mV (max) −2.8 −2.8 −2.8 mV/V (max) −3.5 −3.5 −3.5 mV/V (max) 130 130 130 nA (max) 150 150 150 nA (max) Minimum Operating Current Reference Voltage Change with Operating Current Change ∆VREF/∆VO Reference Voltage Changewith Output Voltage Change IFB Conditions 36 IRMIN ≤ IR ≤ 1mA VOUT ≥ 1.6V (Note 7) 0.3 1 mA ≤ IR ≤ 12 mA VOUT ≥ 1.6V(Note 7) 0.6 IR = 0.1 mA µA mV mV −1.69 Feedback Current Average Reference Voltage Temperature Coefficient (Note 8) V mV/V 70 nA VOUT = 2.5V IR = 10mA 20 IR = 1mA 15 IR =100µA 15 ppm/˚C ppm/˚C ± 50 ± 50 ± 50 ppm/˚C (max) ∆T = −40˚C to +125˚C ZOUT Dynamic Output Impedance IR = 1 mA, f = 120 Hz, IAC = 0.1 IR VOUT = VREF VOUT = 10V 0.3 2 Ω Ω eN Wideband Noise IR = 100 µA VOUT = VREF 10 Hz ≤ f ≤ 10 kHz 20 µVrms ∆VREF Reference Voltage Long Term Stability (Note 9) t = 1000 hrs, IR = 100 µA T = 25˚C ± 0.1˚C 120 ppm VHYST Thermal Hysteresis (Note 10) ∆T = −40˚C to +125˚C 0.3 mV/V www.national.com 4 LM4051 LM4051-ADJ (Adjustable) Electrical Characteristics (Continued) Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions. Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJmax (maximum junction temperature), θJA (junction to ambient thermal resistance), and TA (ambient temperature). The maximum allowable power dissipation at any temperature is PDmax = (TJmax − TA)/θJA or the number given in the Absolute Maximum Ratings, whichever is lower. For the LM4051, TJmax = 125˚C, and the typical thermal resistance (θJA), when board mounted, is 280˚C/W for the SOT-23 package. Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged directly into each pin. Note 4: Typicals are at TJ = 25˚C and represent most likely parametric norm. Note 5: Limits are 100% production tested at 25˚C. Limits over temperature are guaranteed through correlation using Statistical Quality Control (SQC) methods. The limits are used to calculate National’s AOQL. Note 6: The boldface (over-temperature) limit for Reverse Breakdown Voltage Tolerance is defined as the room temperature Reverse Breakdown Voltage Tolerance ± [(∆V R/∆T)(max ∆T)(VR)]. Where, ∆VR/∆T is the VR temperature coefficient, max∆T is the maximum difference in temperature from the reference point of 25 ˚C to T MAX or TMIN, and VR is the reverse breakdown voltage. The total over-temperature tolerance for the different grades in the industrial temperature range where max∆T=65˚C is shown below: A-grade: ± 0.425% = ± 0.1% ± 50 ppm/˚C x 65˚C B-grade: ± 0.525% = ± 0.2% ± 50 ppm/˚C x 65˚C C-grade: ± 0.825% = ± 0.5% ± 50 ppm/˚C x 65˚C Therefore, as an example, the A-grade LM4051-1.2 has an over-temperature Reverse Breakdown Voltage tolerance of ± 1.2V x 0.425% = ± 5.2 mV. Note 7: When VOUT ≤ 1.6V, the LM4051-ADJ in the SOT-23 package must operate at reduced IR. This is caused by the series resistance of the die attach between the die (-) output and the package (-) output pin. See the Output Saturation curve in the Typical Performance Characteristics section. Note 8: Reference voltage and temperature coefficient will change with output voltage. See Typical Performance Characteristics curves. Note 9: Long term stability is VR @ 25˚C measured during 1000 hrs. Note 10: Thermal hysteresis is defined as the difference in voltage measured at +25˚C after cycling to temperature -40˚C and the 25˚C measurement after cycling to temperature +125˚C. 5 www.national.com LM4051 Typical Performance Characteristics Temperature Drift for Different Average Temperature Coefficient Output Impedance vs Frequency 10122219 10122204 Noise Voltage Reverse Characteristics and Minimum Operating Current 10122205 10122209 Start-Up Characteristics 10122208 10122207 www.national.com 6 LM4051 Typical Performance Characteristics (Continued) Reference Voltage vs Output Voltage and Temperature Reference Voltage vs Temperature and Output Voltage 10122211 10122210 Feedback Current vs Output Voltage and Temperature Output Saturation (SOT-23 Only) 10122212 10122233 Output Impedance vs Frequency Output Impedance vs Frequency 10122213 10122214 7 www.national.com LM4051 Typical Performance Characteristics (Continued) Reverse Characteristics 10122216 10122215 Large Signal Response 10122218 10122217 Thermal Hysteresis 10122250 www.national.com 8 LM4051 Functional Block Diagram 10122221 *LM4051-ADJ only **LM4051-1.2 only LM4051 even when the supply voltage is at its minimum and the load current is at its maximum value. When the supply voltage is at its maximum and IL is at its minimum, RS should be large enough so that the current flowing through the LM4051 is less than 12 mA. RS should be selected based on the supply voltage, (VS), the desired load and operating current, (IL and IQ), and the LM4051’s reverse breakdown voltage, VR. Applications Information The LM4051 is a precision micro-power curvature-corrected bandgap shunt voltage reference. For space critical applications, the LM4051 is available in the sub-miniature SOT-23 surface-mount package. The LM4051 has been designed for stable operation without the need of an external capacitor connected between the “+” pin and the “−” pin. If, however, a bypass capacitor is used, the LM4051 remains stable. Design effort is further reduced with the choice of either a fixed 1.2V or an adjustable reverse breakdown voltage. The minimum operating current is 60 µA for the LM4051-1.2 and the LM4051-ADJ. Both versions have a maximum operating current of 12 mA. LM4051s using the SOT-23 package have pin 3 connected as the (-) output through the package’s die attach interface. Therefore, the LM4051-1.2’s pin 3 must be left floating or connected to pin 2 and the LM4051-ADJ’s pin 3 is the (-) output. The LM4051-ADJ’s output voltage can be adjusted to any value in the range of 1.24V through 10V. It is a function of the internal reference voltage (VREF) and the ratio of the external feedback resistors as shown in Figure 2 . The output voltage is found using the equation (1) VO = VREF[(R2/R1) + 1] The typical thermal hysteresis specification is defined as the change in +25˚C voltage measured after thermal cycling. The device is thermal cycled to temperature -40˚C and then measured at 25˚C. Next the device is thermal cycled to temperature +125˚C and again measured at 25˚C. The resulting VOUT delta shift between the 25˚C measurements is thermal hysteresis. Thermal hysteresis is common in precision references and is induced by thermal-mechanical package stress. Changes in environmental storage temperature, operating temperature and board mounting temperature are all factors that can contribute to thermal hysteresis. In a conventional shunt regulator application (Figure 1), an external series resistor (RS) is connected between the supply voltage and the LM4051. RS determines the current that flows through the load (IL) and the LM4051 (IQ). Since load current and supply voltage may vary, RS should be small enough to supply at least the minimum acceptable IQ to the (2) where VO is the output voltage. The actual value of the internal VREF is a function of VO. The “corrected” VREF is determined by (3) VREF = VO (∆VREF/∆VO) + VY where VY = 1.22V ∆VREF/∆VO is found in the Electrical Characteristics and is typically −1.55 mV/V. You can get a more accurate indication of the output voltage by replacing the value of VREF in equation (1) with the value found using equation (3). 9 www.national.com LM4051 Typical Applications 10122222 FIGURE 1. Shunt Regulator 10122234 FIGURE 2. Adjustable Shunt Regulator 10122224 FIGURE 3. Bounded amplifier reduces saturation-induced delays and can prevent succeeding stage damage. Nominal clamping voltage is ± VO (LM4051’s reverse breakdown voltage) +2 diode VF. www.national.com 10 LM4051 Typical Applications (Continued) 10122226 10122220 FIGURE 7. Bidirectional Clamp ± 2.4V FIGURE 4. Voltage Level Detector 10122223 FIGURE 5. Voltage Level Detector 10122235 FIGURE 8. Bidirectional Adjustable Clamp ± 18V to ± 2.4V 10122225 FIGURE 6. Fast Positive Clamp 2.4V + VD1 11 10122236 www.national.com FIGURE 9. Bidirectional Adjustable Clamp ± 2.4V to ± 6V LM4051 Typical Applications (Continued) 10122237 FIGURE 10. Simple Floating Current Detector 10122238 FIGURE 11. Current Source Note 11: *D1 can be any LED, VF = 1.5V to 2.2V at 3 mA. D1 may act as an indicator. D1 will be on if ITHRESHOLD falls below the threshold current, except with I = O. www.national.com 12 LM4051 Typical Applications (Continued) 10122239 FIGURE 12. Precision Floating Current Detector 10122229 10122228 FIGURE 13. Precision 1 µA to 1 mA Current Sources 13 www.national.com LM4051 Precision Micropower Shunt Voltage Reference Physical Dimensions inches (millimeters) unless otherwise noted Plastic Surface Mount Package (M3) NS Package Number MF03A (JEDEC Registration TO-236AB) 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. 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