LM4051 Precision Micropower Shunt Voltage Reference
March 2005
LM4051 Precision Micropower Shunt Voltage Reference
General Description
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.
j Low output noise
(10 Hz to 10kHz)
j Wide operating current range j Industrial temperature range j Extended temperature range j Low temperature coefficient
20µVrms 60µA to 12mA −40˚C to +85˚C −40˚C to +125˚C 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
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
Key Specifications (LM4051-1.2)
j Output voltage tolerance
(A grade, 25˚C)
± 0.1%(max)
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
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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 LM4051 Supplied as 1000 Units, Tape and Reel LM4051AIM3-1.2 LM4051AIM3-ADJ LM4051BIM3-1.2 LM4051BIM3-ADJ LM4051CIM3-1.2 LM4051CIM3-ADJ LM4051 Supplied as 3000 Units, Tape and Reel LM4051AIM3X-1.2 LM4051AIM3X-ADJ LM4051BIM3X-1.2 LM4051BIM3X-ADJ LM4051CIM3X-1.2 LM4051CIM3X-ADJ
± 0.1%, 50 ppm/˚C max (A grade) ± 0.2%, 50 ppm/˚C max (B grade) ± 0.5%, 50 ppm/˚C max (C grade)
Extended Temperature Range (−40˚C to +125˚C) Reverse Breakdown Voltage Tolerance at 25˚C and Average Reverse Breakdown Voltage Temperature Coefficient LM4051 Supplied as 1000 Units, Tape and Reel LM4051AEM3-1.2 LM4051AEM3-ADJ LM4051BEM3-1.2 LM4051BEM3-ADJ LM4051CEM3-1.2 LM4051CEM3-ADJ LM4051 Supplied as 3000 Units, Tape and Reel LM4051AEM3X-1.2 LM4051AEM3X-ADJ LM4051BEM3X-1.2 LM4051BEM3X-ADJ LM4051CEM3X-1.2 LM4051CEM3X-ADJ
± 0.1%, 50 ppm/˚C max (A grade) ± 0.2%, 50 ppm/˚C max (B grade) ± 0.5%, 50 ppm/˚C max (C grade)
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 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% Field Definition
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LM4051
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Reverse Current Forward Current Maximum Output Voltage (LM4051-ADJ) Power Dissipation (TA = 25˚C) (Note 2) M3 Package Storage Temperature Lead Temperature M3 Packages Vapor phase (60 seconds) Infrared (15 seconds) ESD Susceptibility +215˚C +220˚C 280 mW −65˚C to +150˚C 15V 20 mA 10 mA
Human Body Model (Note 3) Machine Model (Note 3)
2 kV 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)
Temperature Range Industrial Temperature Range Extended Temperature Range Reverse Current LM4051-1.2 LM4051-ADJ Output Voltage Range LM4051-ADJ 1.24V to 10V 60 µA to 12 mA 60 µA to 12 mA (Tmin ≤ TA ≤ Tmax) −40˚C ≤ TA ≤ +85˚C −40˚C ≤ TA ≤ +125˚C
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 Parameter Reverse Breakdown Voltage Reverse Breakdown Voltage Tolerance (Note 6) Conditions IR = 100 µA IR = 100 µA Industrial Temp. Range Extended Temp. Range IRMIN Minimum Operating Current 39 60 65 ∆VR/∆T Average Reverse Breakdown Voltage Temperature Coefficient (Note 6) IR= 10 mA IR = 1 mA IR = 100 µA ∆T = −40˚C to 125˚C ∆VR/∆IR Reverse Breakdown Voltage Change with Operating Current Change IRMIN ≤ IR ≤ 1 mA 60 65 60 65 LM4051AIM3 LM4051BIM3 LM4051CIM3 Typical LM4051AEM3 LM4051BEM3 LM4051CEM3 (Note 4) (Limits) (Limits) (Limts) (Note 5) (Note 5) (Note 5) 1.225 Units (Limit) V
± 1.2 ± 5.2 ± 7.4
± 2.4 ± 6.4 ± 8.6
±6 ± 10.1 ± 12.2
mV (max) mV (max) mV (max) µA µA (max) µA (max) ppm/˚C ppm/˚C
± 20 ± 15 ± 15
0.3 1.1 1.5 1.1 1.5 6.0 8.0 1.1 1.5 6.0 8.0
± 50
± 50
± 50
ppm/˚C (max) mV mV (max) mV (max) mV mV (max) mV (max) Ω µVrms
1 mA ≤ IR ≤ 12 mA
1.8 6.0 8.0
ZR eN ∆VR
Reverse Dynamic Impedance Wideband Noise Reverse Breakdown Voltage Long Term Stability (Note 9) Thermal Hysteresis (Note 10)
IR = 1 mA, f = 120 Hz IR = 100 µA 10 Hz ≤ f ≤ 10 kHz t = 1000 hrs T = 25˚C ± 0.1˚C IR = 100 µA ∆T = −40˚C to 125˚C
0.5 20
120 0.36
ppm mV/V
VHYST
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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 Parameter Reference Voltage Reference Voltage Tolerance (Note 6), (Note 8) Conditions IR = 100 µA, VOUT = 5V IR = 100 µA, VOUT = 5V Industrial Temp. Range Extended Temp. Range IRMIN Minimum Operating Current Industrial Temp. Range Extended Temp. Range ∆VREF/∆IR Reference Voltage Change with Operating Current Change IRMIN ≤ IR ≤ 1mA VOUT ≥ 1.6V (Note 7) 1 mA ≤ IR ≤ 12 mA VOUT ≥ 1.6V(Note 7) 0.3 1.1 1.5 0.6 6 8 ∆VREF/∆VO Reference Voltage Changewith Output Voltage Change IFB Feedback Current IR = 0.1 mA −1.69 −2.8 −3.5 70 130 150 ∆VREF/∆T Average Reference Voltage Temperature Coefficient (Note 8) VOUT = 2.5V IR = 10mA IR = 1mA IR =100µA ∆T = −40˚C to +125˚C ZOUT Dynamic Output Impedance IR = 1 mA, f = 120 Hz, IAC = 0.1 IR VOUT = VREF VOUT = 10V eN Wideband Noise IR = 100 µA VOUT = VREF 10 Hz ≤ f ≤ 10 kHz t = 1000 hrs, IR = 100 µA T = 25˚C ± 0.1˚C ∆T = −40˚C to +125˚C 0.3 2 20 Ω Ω µVrms 20 15 15 ppm/˚C ppm/˚C 130 150 130 150 −2.8 −3.5 −2.8 −3.5 6 8 6 8 1.1 1.5 1.1 1.5 36 60 65 70 60 65 70 65 70 75 Typical LM4051AIM3 LM4051BIM3 LM4051CIM3 (Note 4) LM4051AEM3 LM4051BEM3 LM4051CEM3 (Limits) (Limits) (Limits) (Note 5) (Note 5) (Note 5) 1.212 Units (Limit)
V
± 1.2 ± 5.2 ± 7.4
± 2.4 ± 6.4 ± 8.6
±6 ± 10.1 ± 12.2
mV (max) mV (max) mV (max) µA µA (max) µA (max) µA (max) mV mV(max) mV(max) mV mV (max) mV (max) mV/V mV/V (max) mV/V (max) nA nA (max) nA (max)
± 50
± 50
± 50
ppm/˚C (max)
∆VREF VHYST
Reference Voltage Long Term Stability (Note 9) Thermal Hysteresis (Note 10)
120
ppm
0.3
mV/V
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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.
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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
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LM4051
Typical Performance Characteristics
Reference Voltage vs Output Voltage and Temperature
(Continued) 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
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LM4051
Typical Performance Characteristics
Reverse Characteristics
(Continued)
10122216
10122215
Large Signal Response
10122218
10122217
Thermal Hysteresis
10122250
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LM4051
Functional Block Diagram
10122221
*LM4051-ADJ only **LM4051-1.2 only
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 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
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.
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]
(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).
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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.
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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
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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.
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LM4051
Typical Applications
(Continued)
10122239
FIGURE 12. Precision Floating Current Detector
10122229
10122228
FIGURE 13. Precision 1 µA to 1 mA Current Sources
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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)
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