LM4128/LM4128Q SOT-23 Precision Micropower Series Voltage Reference General Description Features Ideal for space critical applications, the LM4128 precision voltage reference is available in the SOT-23 surface-mount package. The LM4128’s advanced design eliminates the need for an external stabilizing capacitor while ensuring stability with capacitive loads up to 10 µF, thus making the LM4128 easy to use. Series references provide lower power consumption than shunt references, since they do not have to idle the maximum possible load current under no load conditions. This advantage, the low quiescent current (60 µA), and the low dropout voltage (400 mV) make the LM4128 ideal for battery-powered solutions. The LM4128 is available in four grades (A, B, C, and D) for greater flexibility. The best grade devices (A) have an initial accuracy of 0.1% with guaranteed temperature coefficient of 75 ppm/°C or less, while the lowest grade parts (D) have an initial accuracy of 1.0% and a tempco of 100 ppm/°C. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Output voltage initial accuracy 0.1% Low temperature coefficient 75 ppm/°C Low Supply Current, 60 µA Enable pin allowing a 3 µA shutdown mode Up to 20 mA output current Voltage options 1.8V, 2.048V, 2.5V, 3.0V, 3.3V, 4.096V Custom voltage options available (1.8V to 4.096V) VIN range of VREF + 400 mV to 5.5V @10 mA Stable with low ESR ceramic capacitors SOT23-5 Package −40°C to 125°C junction temperature range LM4128AQ/BQ/CQ/DQ are AEC-Q100 Grade 1 qualified and are manufactured on an Automotive Grade Flow Applications ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Instrumentation & Process Control Test Equipment Data Acquisition Systems Base Stations Servo Systems Portable, Battery Powered Equipment Automotive & Industrial Electronics Precision Regulators Battery Chargers Communications Medical Equipment Typical Application Circuit 20211001 *Note: The capacitor CIN is required and the capacitor COUT is optional. © 2008 National Semiconductor Corporation 202110 www.national.com LM4128/LM4128Q SOT-23 Precision Micropower Series Voltage Reference October 23, 2008 LM4128/LM4128Q Connection Diagram Top View 20211002 SOT23-5 Package NS Package Number MF05A Ordering Information Input Output Voltage Accuracy at 25°C And Temperature Coefficient 0.1%, 75 ppm/°C (A grade) 0.2%, 75 ppm/°C (B grade) 0.5%, 100 ppm/°C (C grade) 1.0%, 100 ppm/°C max (D grade) www.national.com LM4128 Supplied as 1000 units, Tape and Reel LM4128 Supplied as 3000 units, Tape and Reel Part Marking LM4128AMF-1.8 LM4128AMFX-1.8 R5AA LM4128AMF-2.0 LM4128AMFX-2.0 R5BA LM4128AMF-2.5 LM4128AMFX-2.5 R5CA LM4128AMF-3.0 LM4128AMFX-3.0 R5DA LM4128AMF-3.3 LM4128AMFX-3.3 R5EA LM4128AMF-4.1 LM4128AMFX-4.1 R5FA LM4128BMF-1.8 LM4128BMFX-1.8 R5AB LM4128BMF-2.0 LM4128BMFX-2.0 R5BB LM4128BMF-2.5 LM4128BMFX-2.5 R5CB LM4128BMF-3.0 LM4128BMFX-3.0 R5DB LM4128BMF-3.3 LM4128BMFX-3.3 R5EB LM4128BMF-4.1 LM4128BMFX-4.1 R5FB LM4128CMF-1.8 LM4128CMFX-1.8 R5AC LM4128CMF-2.0 LM4128CMFX-2.0 R5BC LM4128CMF-2.5 LM4128CMFX-2.5 R5CC LM4128CMF-3.0 LM4128CMFX-3.0 R5DC LM4128CMF-3.3 LM4128CMFX-3.3 R5EC LM4128CMF-4.1 LM4128CMFX-4.1 R5FC LM4128DMF-1.8 LM4128DMFX-1.8 R5AD LM4128DMF-2.0 LM4128DMFX-2.0 R5BD LM4128DMF-2.5 LM4128DMFX-2.5 R5CD LM4128DMF-3.0 LM4128DMFX-3.0 R5DD LM4128DMF-3.3 LM4128DMFX-3.3 R5ED LM4128DMF-4.1 LM4128DMFX-4.1 R5FD 2 Feature 0.1%, 75 ppm/°C (AQ grade) 0.2%, 75 ppm/°C (BQ grade) 0.5%, 100 ppm/°C (CQ grade) 1.0%, 100 ppm/°C max (DQ grade) LM4128 Supplied as 1000 units, Tape and Reel LM4128 Supplied as 3000 units, Tape and Reel Part Marking Feature LM4128AQ1MF1.8 LM4128AQ1MFX1.8 R6AA LM4128AQ1MF2.0 LM4128AQ1MFX2.0 R6BA LM4128AQ1MF2.5 LM4128AQ1MFX2.5 R6CA AEC-Q100 Grade 1 qualified. Automotive Grade Production Flow* LM4128AQ1MF3.0 LM4128AQ1MFX3.0 R6DA LM4128AQ1MF3.3 LM4128AQ1MFX3.3 R6EA LM4128AQ1MF4.1 LM4128AQ1MFX4.1 R6FA LM4128BQ1MF1.8 LM4128BQ1MFX1.8 R6AB LM4128BQ1MF2.0 LM4128BQ1MFX2.0 R6BB LM4128BQ1MF2.5 LM4128BQ1MFX2.5 R6CB LM4128BQ1MF3.0 LM4128BQ1MFX3.0 R6DB LM4128BQ1MF3.3 LM4128BQ1MFX3.3 R6EB LM4128BQ1MF4.1 LM4128BQ1MFX4.1 R6FB LM4128CQ1MF1.8 LM4128CQ1MFX1.8 R6AC LM4128CQ1MF2.0 LM4128CQ1MFX2.0 R6BC LM4128CQ1MF2.5 LM4128CQ1MFX2.5 R6CC LM4128CQ1MF3.0 LM4128CQ1MFX3.0 R6DC LM4128CQ1MF3.3 LM4128CQ1MFX3.3 R6EC LM4128CQ1MF4.1 LM4128CQ1MFX4.1 R6FC LM4128DQ1MF1.8 LM4128DQ1MFX1.8 R6AD LM4128DQ1MF2.0 LM4128DQ1MFX2.0 R6BD LM4128DQ1MF2.5 LM4128DQ1MFX2.5 R6CD LM4128DQ1MF3.0 LM4128DQ1MFX3.0 R6DD LM4128DQ1MF3.3 LM4128DQ1MFX3.3 R6ED LM4128DQ1MF4.1 LM4128DQ1MFX4.1 R6FD AEC-Q100 Grade 1 qualified. Automotive Grade Production Flow* AEC-Q100 Grade 1 qualified. Automotive Grade Production Flow* AEC-Q100 Grade 1 qualified. Automotive Grade Production Flow* *Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including defect detection methodologies. Reliability qualification is compliant with the requirements and temperature grades defined in the AEC-Q100 standard. Automotive grade products are identified with the letter Q. For more information go to http://www.national.com/automotive. Pin Descriptions Pin # Name Function 1 N/C No connect pin, leave floating 2 GND Ground 3 EN Enable pin 4 VIN Input supply 5 VREF Reference output 3 www.national.com LM4128/LM4128Q Input Output Voltage Accuracy at 25°C And Temperature Coefficient LM4128/LM4128Q Vapor Phase (60 sec) Infrared (15sec) ESD Susceptibility (Note 3) Human Body Model Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Maximum Voltage on any input Output short circuit duration Power Dissipation (TA = 25°C) (Note 2) Storage Temperature Range -0.3 to 6V Indefinite Maximum Input Supply Voltage Maximum Enable Input Voltage Maximum Load Current Junction Temperature Range (TJ) 350 mW −65°C to 150°C (soldering, 10sec) 2 kV Operating Ratings Lead Temperature 215°C 220°C 5.5V VIN 20mA −40°C to +125°C 260°C Electrical Characteristics LM4128-1.8 (VOUT = 1.8V) Limits in standard type are for TJ = 25°C only, and limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise specified VIN = 5V and ILOAD = 0A. Symbol VREF Parameter Min Typ Max (Note 4) (Note 5) (Note 4) Unit Output Voltage Initial Accuracy LM4128A-1.8 (A Grade - 0.1%) -0.1 +0.1 LM4128B-1.8 (B Grade - 0.2%) -0.2 +0.2 LM4128C-1.8 (C Grade - 0.5%) -0.5 +0.5 LM4128D-1.8 (D Grade - 1.0%) -1.0 +1.0 TCVREF / °C (Note Temperature Coefficient 6) IQ Conditions LM4128A-1.8 % 75 LM4128B-1.8 75 LM4128C-1.8 100 LM4128D-1.8 100 60 100 µA Supply Current in Shutdown EN = 0V 3 7 µA ΔVREF/ΔVIN Line Regulation VREF + 400 mV ≤ VIN ≤ 5.5V 30 ΔVREF/ΔILOAD Load Regulation 0 mA ≤ ILOAD ≤ 20 mA 25 Long Term Stability (Note 7) 1000 Hrs 50 Thermal Hysteresis (Note 8) -40°C ≤ TJ ≤ +125°C 75 IQ_SD ΔVREF VIN - VREF Supply Current ppm / °C ppm / V 120 ppm / mA ppm Dropout Voltage (Note 9) ILOAD = 10 mA 200 VN Output Noise Voltage 0.1 Hz to 10 Hz 170 ISC Short Circuit Current 75 mA VIL Enable Pin Maximum Low Input Level 35 %V VIH Enable Pin Minimum High Input Level www.national.com 65 4 400 mV µVPP %V Limits in standard type are for TJ = 25°C only, and limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise specified VIN = 5V and ILOAD = 0A. Symbol VREF Parameter Min Typ Max (Note 4) (Note 5) (Note 4) Unit Output Voltage Initial Accuracy LM4128A-2.0 (A Grade - 0.1%) -0.1 +0.1 LM4128B-2.0 (B Grade - 0.2%) -0.2 +0.2 LM4128C-2.0 (C Grade - 0.5%) -0.5 +0.5 LM4128D-2.0 (D Grade - 1.0%) -1.0 +1.0 TCVREF / °C (Note Temperature Coefficient 6) IQ Conditions LM4128A-2.0 % 75 LM4128B-2.0 75 LM4128C-2.0 100 LM4128D-2.0 100 60 100 µA Supply Current in Shutdown EN = 0V 3 7 µA ΔVREF/ΔVIN Line Regulation VREF + 400 mV ≤ VIN ≤ 5.5V 30 ΔVREF/ΔILOAD Load Regulation 0 mA ≤ ILOAD ≤ 20 mA 25 Long Term Stability (Note 7) 1000 Hrs 50 Thermal Hysteresis (Note 8) -40°C ≤ TJ ≤ +125°C 75 IQ_SD ΔVREF VIN - VREF Supply Current ppm / °C ppm / V 120 ppm / mA ppm Dropout Voltage (Note 9) ILOAD = 10 mA 175 VN Output Noise Voltage 0.1 Hz to 10 Hz 190 ISC Short Circuit Current 75 mA VIL Enable Pin Maximum Low Input Level 35 %V VIH Enable Pin Minimum High Input Level 65 5 400 mV µVPP %V www.national.com LM4128/LM4128Q Electrical Characteristics LM4128-2.0 (VOUT = 2.048V) LM4128/LM4128Q Electrical Characteristics LM4128-2.5 (VOUT = 2.5V) Limits in standard type are for TJ = 25°C only, and limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise specified VIN = 5V and ILOAD = 0A. Symbol VREF Parameter Min Typ Max (Note 4) (Note 5) (Note 4) Unit Output Voltage Initial Accuracy LM4128A-2.5 (A Grade - 0.1%) -0.1 +0.1 LM4128B-2.5 (B Grade - 0.2%) -0.2 +0.2 LM4128C-2.5 (C Grade - 0.5%) -0.5 +0.5 LM4128D-2.5 (D Grade - 1.0%) -1.0 +1.0 TCVREF / °C (Note Temperature Coefficient 6) IQ Conditions LM4128A-2.5 % 75 LM4128B-2.5 75 LM4128C-2.5 100 LM4128D-2.5 100 60 100 µA Supply Current in Shutdown EN = 0V 3 7 µA ΔVREF/ΔVIN Line Regulation VREF + 400 mV ≤ VIN ≤ 5.5V 50 ΔVREF/ΔILOAD Load Regulation 0 mA ≤ ILOAD ≤ 20 mA 25 Long Term Stability (Note 7) 1000 Hrs 50 Thermal Hysteresis (Note 8) -40°C ≤ TJ ≤ +125°C 75 IQ_SD ΔVREF VIN - VREF Supply Current ppm / °C ppm / V 120 ppm / mA ppm Dropout Voltage (Note 9) ILOAD = 10 mA 175 VN Output Noise Voltage 0.1 Hz to 10 Hz 275 ISC Short Circuit Current 75 mA VIL Enable Pin Maximum Low Input Level 35 %V VIH Enable Pin Minimum High Input Level www.national.com 65 6 400 mV µVPP %V Limits in standard type are for TJ = 25°C only, and limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise specified VIN = 5V and ILOAD = 0A. Symbol VREF Parameter Min Typ Max (Note 4) (Note 5) (Note 4) Unit Output Voltage Initial Accuracy LM4128A-3.0 (A Grade - 0.1%) -0.1 +0.1 LM4128B-3.0 (B Grade - 0.2%) -0.2 +0.2 LM4128C-3.0 (C Grade - 0.5%) -0.5 +0.5 LM4128D-3.0 (D Grade - 1.0%) -1.0 +1.0 TCVREF / °C (Note Temperature Coefficient 6) IQ Conditions LM4128A-3.0 % 75 LM4128B-3.0 75 LM4128C-3.0 100 LM4128D-3.0 100 60 100 µA Supply Current in Shutdown EN = 0V 3 7 µA ΔVREF/ΔVIN Line Regulation VREF + 400 mV ≤ VIN ≤ 5.5V 70 ΔVREF/ΔILOAD Load Regulation 0 mA ≤ ILOAD ≤ 20 mA 25 Long Term Stability (Note 7) 1000 Hrs 50 Thermal Hysteresis (Note 8) -40°C ≤ TJ ≤ +125°C 75 IQ_SD ΔVREF VIN - VREF Supply Current ppm / °C ppm / V 120 ppm / mA ppm Dropout Voltage (Note 9) ILOAD = 10 mA 175 VN Output Noise Voltage 0.1 Hz to 10 Hz 285 ISC Short Circuit Current 75 mA VIL Enable Pin Maximum Low Input Level 35 %V VIH Enable Pin Minimum High Input Level 65 7 400 mV µVPP %V www.national.com LM4128/LM4128Q Electrical Characteristics LM4128-3.0 (VOUT = 3.0V) LM4128/LM4128Q Electrical Characteristics LM4128-3.3 (VOUT = 3.3V) Limits in standard type are for TJ = 25°C only, and limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise specified VIN = 5V and ILOAD = 0A. Symbol VREF Parameter Min Typ Max (Note 4) (Note 5) (Note 4) Unit Output Voltage Initial Accuracy LM4128A-3.3 (A Grade - 0.1%) -0.1 +0.1 LM4128B-3.3 (B Grade - 0.2%) -0.2 +0.2 LM4128C-3.3 (C Grade - 0.5%) -0.5 +0.5 LM4128D-3.3 (D Grade - 1.0%) -1.0 +1.0 TCVREF / °C (Note Temperature Coefficient 6) IQ Conditions LM4128A-3.3 % 75 LM4128B-3.3 75 LM4128C-3.3 100 LM4128D-3.3 100 60 100 µA Supply Current in Shutdown EN = 0V 3 7 µA ΔVREF/ΔVIN Line Regulation VREF + 400 mV ≤ VIN ≤ 5.5V 85 ΔVREF/ΔILOAD Load Regulation 0 mA ≤ ILOAD ≤ 20 mA 25 Long Term Stability (Note 7) 1000 Hrs 50 Thermal Hysteresis (Note 8) -40°C ≤ TJ ≤ +125°C 75 IQ_SD ΔVREF VIN - VREF Supply Current ppm / °C ppm / V 120 ppm / mA ppm Dropout Voltage (Note 9) ILOAD = 10 mA 175 VN Output Noise Voltage 0.1 Hz to 10 Hz 310 ISC Short Circuit Current 75 mA VIL Enable Pin Maximum Low Input Level 35 %V VIH Enable Pin Minimum High Input Level www.national.com 65 8 400 mV µVPP %V Limits in standard type are for TJ = 25°C only, and limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C unless otherwise specified. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise specified VIN = 5V and ILOAD = 0A. Symbol VREF Parameter IQ Min Typ Max (Note 4) (Note 5) (Note 4) LM4128A-4.1 (A Grade - 0.1%) -0.1 +0.1 LM4128B-4.1 (B Grade - 0.2%) -0.2 +0.2 LM4128C-4.1 (C Grade - 0.5%) -0.5 +0.5 LM4128D-4.1 (D Grade - 1.0%) -1.0 +1.0 LM4128A-4.1 75 LM4128C-4.1 100 LM4128D-4.1 100 Supply Current ppm / °C 60 100 µA 3 7 µA EN = 0V ΔVREF/ΔVIN Line Regulation VREF + 400 mV ≤ VIN ≤ 5.5V 100 ΔVREF/ΔILOAD Load Regulation 0 mA ≤ ILOAD ≤ 20 mA 25 Long Term Stability (Note 7) 1000 Hrs 50 Thermal Hysteresis (Note 8) -40°C ≤ TJ ≤ +125°C 75 VIN - VREF % 75 LM4128B-4.1 Supply Current in Shutdown ΔVREF Unit Output Voltage Initial Accuracy TCVREF / °C (Note Temperature Coefficient 6) IQ_SD Conditions ppm / V 120 ppm / mA ppm Dropout Voltage (Note 9) ILOAD = 10 mA 175 VN Output Noise Voltage 0.1 Hz to 10 Hz 350 ISC Short Circuit Current 75 mA VIL Enable Pin Maximum Low Input Level 35 %V VIH Enable Pin Minimum High Input Level 400 mV µVPP 65 %V Note 1: Absolute Maximum Ratings indicate limits beyond which damage may occur to the device. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications, see Electrical Characteristics. Note 2: Without PCB copper enhancements. The maximum power dissipation must be de-rated at elevated temperatures and is limited by TJMAX (maximum junction temperature), θJ-A (junction to ambient thermal resistance) and TA (ambient temperature). The maximum power dissipation at any temperature is: PDissMAX = (TJMAX - TA) /θJ-A up to the value listed in the Absolute Maximum Ratings. θJ-A for SOT23-5 package is 220°C/W, TJMAX = 125°C. Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. Note 4: Limits are 100% production tested at 25°C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control. Note 5: Typical numbers are at 25°C and represent the most likely parametric norm. Note 6: Temperature coefficient is measured by the "Box" method; i.e., the maximum ΔVREF is divided by the maximum ΔT. Note 7: Long term stability is VREF @25°C measured during 1000 hrs. Note 8: Thermal hysteresis is defined as the change in +25°C output voltage before and after cycling the device from (-40°C to 125°C). Note 9: Dropout voltage is defined as the minimum input to output differential at which the output voltage drops by 0.5% below the value measured with a 5V input. 9 www.national.com LM4128/LM4128Q Electrical Characteristics LM4128-4.1 (VOUT = 4.096V) LM4128/LM4128Q Typical Performance Characteristics for 2.5V Output Voltage vs Temperature Load Regulation 20211054 20211055 Line Regulation 0.1 - 10 Hz Noise 20211021 20211056 Output Voltage Noise Spectrum Power Supply Rejection Ratio vs Frequency 20211057 www.national.com 20211058 10 LM4128/LM4128Q Dropout vs Load to 0.5% Accuracy Typical Long Term Stability 20211008 20211030 Supply Current vs Input Voltage Shutdown IQ vs Input Voltage 20211010 20211053 Ground Current vs Load Current Line Transient Response VIN = 3V to 5V 20211051 20211018 11 www.national.com LM4128/LM4128Q Load Transient Response ILOAD = 0 to 10mA Short-Circuit Protection and Recovery 20211082 20211050 Start-Up Response 20211083 www.national.com 12 THEORY OF OPERATION The foundation of any voltage reference is the band-gap circuit. While the reference in the LM4128 is developed from the gate-source voltage of transistors in the IC, principles of the band-gap circuit are easily understood using a bipolar example. For a detailed analysis of the bipolar band-gap circuit, please refer to Application Note AN-56. SUPPLY AND ENABLE VOLTAGES To ensure proper operation, VEN and VIN must be within a specified range. An acceptable range of input voltages is VIN > VREF + 400 mV (ILOAD ≤ 10 mA) The enable pin uses an internal pull-up current source (IPULL_UP ≊ 2 µA) that may be left floating or triggered by an external source. If the part is not enabled by an external source, it may be connected to VIN. An acceptable range of enable voltages is given by the enable transfer characteristics. See the Electrical Characteristics section and Enable Transfer Characteristics figure for more detail. Note, the part will not operate correctly for VEN > VIN. 20211038 FIGURE 1. Illustrative Temperature Profile This may be expressed analytically as the following: COMPONENT SELECTION A small ceramic (X5R or X7R) capacitor on the input must be used to ensure stable operation. The value of CIN must be sized according to the output capacitor value. The value of CIN must satisfy the relationship CIN ≥ COUT. When no output capacitor is used, CIN must have a minimum value of 0.1 µF. Noise on the power-supply input may affect the output noise. Larger input capacitor values (typically 4.7 µF to 22 µF) may help reduce noise on the output and significantly reduce overshoot during startup. Use of an additional optional bypass capacitor between the input and ground may help further reduce noise on the output. With an input capacitor, the LM4128 will drive any combination of resistance and capacitance up to VREF/20 mA and 10 µF respectively. The LM4128 is designed to operate with or without an output capacitor and is stable with capacitive loads up to 10 µF. Connecting a capacitor between the output and ground will significantly improve the load transient response when switching from a light load to a heavy load. The output capacitor should not be made arbitrarily large because it will effect the turn-on time as well as line and load transients. While a variety of capacitor chemistry types may be used, it is typically advisable to use low esr ceramic capacitors. Such capacitors provide a low impedance to high frequency signals, effectively bypassing them to ground. Bypass capacitors should be mounted close to the part. Mounting bypass capacitors close to the part will help reduce the parasitic trace components thereby improving performance. Where VHYS = Thermal hysteresis expressed in ppm VREF = Nominal preset output voltage VREF1 = VREF before temperature fluctuation VREF2 = VREF after temperature fluctuation. The LM4128 features a low thermal hysteresis of 190 µV from -40°C to 125°C. TEMPERATURE COEFFICIENT Temperature drift is defined as the maximum deviation in output voltage over the operating temperature range. This deviation over temperature may be illustrated as shown in Figure 2. SHORT CIRCUITED OUTPUT The LM4128 features indefinite short circuit protection. This protection limits the output current to 75 mA when the output is shorted to ground. 20211039 FIGURE 2. Illustrative Temperature Coefficient Profile TURN ON TIME Turn on time is defined as the time taken for the output voltage to rise to 90% of the preset value. The turn on time depends on the load. The turn on time is typically 33.2 µs when driving a 1µF load and 78.8 µs when driving a 10 µF load. Some users may experience an extended turn on time (up to 10 ms) under brown out conditions and low temperatures (-40°C). Temperature coefficient may be expressed analytically as the following: 13 www.national.com LM4128/LM4128Q THERMAL HYSTERESIS Thermal hysteresis is defined as the change in output voltage at 25ºC after some deviation from 25ºC. This is to say that thermal hysteresis is the difference in output voltage between two points in a given temperature profile. An illustrative temperature profile is shown in Figure 1. Application Information LM4128/LM4128Q VREF is in volts (V), VERROR is in milli-volts (mV), and n is the number of bits. mV to ppm error in output voltage: TD = Temperature drift VREF = Nominal preset output voltage VREF_MIN = Minimum output voltage over operating temperature range VREF_MAX = Maximum output voltage over operating temperature range ΔT = Operating temperature range. The LM4128 features a low temperature drift of 75 ppm (max) to 100 ppm (max), depending on the grade, from -40°C to 125°C. Where: VREF is in volts (V) and VERROR is in milli-volts (mV). Voltage error (mV) to percentage error (percent): LONG TERM STABILITY Long-term stability refers to the fluctuation in output voltage over a long period of time (1000 hours). The LM4128 features a typical long-term stability of 50 ppm over 1000 hours. The measurements are made using 5 units of each voltage option, at a nominal input voltage (5V), with no load, at room temperature. Where: VREF is in volts (V) and VERROR is in milli-volts (mV). EXPRESSION OF ELECTRICAL CHARACTERISTICS Electrical characteristics are typically expressed in mV, ppm, or a percentage of the nominal value. Depending on the application, one expression may be more useful than the other. To convert one quantity to the other one may apply the following: ppm to mV error in output voltage: PRINTED CIRCUIT BOARD and LAYOUT CONSIDERATIONS References in SOT packages are generally less prone to PC board mounting than devices in Small Outline (SOIC) packages. To minimize the mechanical stress due to PC board mounting that can cause the output voltage to shift from its initial value, mount the reference on a low flex area of the PC board, such as near the edge or a corner. The part may be isolated mechanically by cutting a U shape slot on the PCB for mounting the device. This approach also provides some thermal isolation from the rest of the circuit. Bypass capacitors must be mounted close to the part. Mounting bypass capacitors close to the part will reduce the parasitic trace components thereby improving performance. Where: VREF is in volts (V) and VERROR is in milli-volts (mV). Bit error (1 bit) to voltage error (mV): www.national.com 14 LM4128/LM4128Q Typical Application Circuits 20211026 FIGURE 3. Voltage Reference with Complimentary Output 20211027 FIGURE 4. Precision Voltage Reference with Force and Sense Output 20211028 FIGURE 5. Programmable Current Source 15 www.national.com LM4128/LM4128Q Physical Dimensions inches (millimeters) unless otherwise noted SOT23-5 Package NS Package Number MF05A www.national.com 16 LM4128/LM4128Q Notes 17 www.national.com LM4128/LM4128Q SOT-23 Precision Micropower Series Voltage Reference Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBENCH www.national.com/webench Audio www.national.com/audio Analog University www.national.com/AU Clock Conditioners www.national.com/timing App Notes www.national.com/appnotes Data Converters www.national.com/adc Distributors www.national.com/contacts Displays www.national.com/displays Green Compliance www.national.com/quality/green Ethernet www.national.com/ethernet Packaging www.national.com/packaging Interface www.national.com/interface Quality and Reliability www.national.com/quality LVDS www.national.com/lvds Reference Designs www.national.com/refdesigns Power Management www.national.com/power Feedback www.national.com/feedback Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www.national.com/led PowerWise www.national.com/powerwise Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors Wireless (PLL/VCO) www.national.com/wireless THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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