LM4040_05

LM4040/4041 Micrel, Inc. LM4040/4041 Precision Micropower Shunt Voltage Reference General Description Ideal for space critical applications, the LM4040 and LM4041 precision voltage references are available in the subminiature (3mm × 1.3mm) SOT-23 surface-mount package. The LM4040 is the available in fixed reverse breakdown voltages of 2.500V, 4.096V and 5.000V. The LM4041 is available with a fixed 1.225V or an adjustable reverse breakdown voltage. The minimum operating current ranges from 60µA for the LM4041-1.2 to 74µA for the LM4040-5.0. LM4040 versions have a maximum operating current of 15mA. LM4041 versions have a maximum operating current of 12mA. The LM4040 and LM4041 have bandgap reference temperature drift curvature correction and low dynamic impedance, ensuring stable reverse breakdown voltage accuracy over a wide range of operating temperatures and currents. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. Features • • • • Small SOT-23 package No output capacitor required Tolerates capacitive loads Fixed reverse breakdown voltages of 1.225, 2.500V, 4.096V and 5.000V • Adjustable reverse breakdown version • Contact Micrel for parts with extended temperature range. Key Specifications • Output voltage tolerance ............................. ±0.1% (max) • Low output noise (10Hz to 100Hz) LM4040 ................................................. 35µVRMS (typ) LM4041 ................................................. 20µVRMS (typ) • Wide operating current range LM4040 ..................................................60µA to 15mA LM4041 ..................................................60µA to 12mA • Industrial temperature range .................. –40°C to +85°C • Low temperature coefficient ................ 100ppm/°C (max) Applications • • • • • • • • Battery-powered equipment Data acquisition systems Instrumentation Process control Energy management Product testing Automotive electronics Precision audio components Typical Applications VS VS RS VR LM4040 LM4041 I Q + IL IL IQ RS VO VO LM4041 Adjustable R1 VO = 1.233 (R2/R1 + 1) R2 Figure 1. LM4040, LM4041 Fixed Shunt Regulator Application Figure 2. LM4041 Adjustable Shunt Regulator Application Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com March 2005 1 M9999-031805 LM4040/4041 Micrel, Inc. Pin Configuration FB 3 + 1 3– 2 Pin 3 must float or be connected to pin 2. Fixed Version SOT-23 (M3) Package Adjustable Version SOT-23 (M3) Package Ordering Information Standard Part Number Pb-Free LM4040CYM3-2.5 LM4040DYM3-2.5 LM4040CYM3-4.1 LM4040DYM3-4.1 LM4040CYM3-5.0 LM4040DYM3-5.0 LM4041CYM3-1.2 LM4041DYM3-1.2 LM4041CYM3-ADJ LM4041DYM3-ADJ Voltage 2.500V 2.500V 4.096V 4.096V 5.000V 5.000V 1.225V 1.225V 1.24V to 10V 1.24V to 10V Accuracy, Temp. Coefficient ±0.5%, 100ppm/°C ±1.0%, 150ppm/°C ±0.5%, 100ppm/°C ±1.0%, 150ppm/°C ±0.5%, 100ppm/°C ±1.0%, 150ppm/°C ±0.5%, 100ppm/°C ±1.0%, 150ppm/°C ±0.5%, 100ppm/°C ±1.0%, 150ppm/°C LM4040CIM3-2.5 LM4040DIM3-2.5 LM4040CIM3-4.1 LM4040DIM3-4.1 LM4040CIM3-5.0 LM4040DIM3-5.0 LM4041CIM3-1.2 LM4041DIM3-1.2 LM4041CIM3-ADJ LM4041DIM3-ADJ SOT-23 Package Markings Example R__ Y__ Field Code 1st Character 1st Character R = Reference Y = Pb-Free Example _2_ Field Code Example __C Field Code 2nd Character 1 = 1.225V 2 = 2.500V 4 = 4.096V 5 = 5.000V A = Adjustable 3rd Character C = ±0.5% D = ±1.0% X = ±0.5% Pb-Free Y = ±1.0% Pb-Free Example: R2C represents Reference, 2.500V, ±0.5% (LM4040CIM3-2.5) Example: Y1C represents Pb-Free, 1.225V, ±0.5% (LM4040CYM3-1.2) Note: If 3rd character is omitted, container will indicate tolerance. M9999-031805 2 March 2005 LM4040/4041 Micrel, Inc. + + VREF FB Functional Diagram LM4040, LM4041 Fixed Functional Diagram LM4041 Adjustable Absolute Maximum Ratings Reverse Current ......................................................... 20mA Forward Current ......................................................... 10mA Maximum Output Voltage LM4041-Adjustable.................................................... 15V Power Dissipation at TA = 25°C (Note 2) ................ 306mW Storage Temperature ................................ –65°C to +150°C Lead Temperature Vapor phase (60 seconds) ............................... +215°C Infrared (15 seconds)....................................... +220°C ESD Susceptibility Human Body Model (Note 3) ............................... 2kV Machine Model (Note 3) .................................... 200V Note 1. Operating Ratings (Notes 1 and 2) Temperature Range (TMIN ≤ TA ≤ TMAX) ............................–40°C ≤ TA ≤ +85°C Reverse Current LM4040-2.5............................................ 60µA to 15mA LM4040-4.1............................................ 68µA to 15mA LM4040-5.0............................................ 74µA to 15mA LM4041-1.2............................................ 60µA to 12mA LM4041-ADJ .......................................... 60µA to 12mA Output Voltage Range LM4041-ADJ ............................................1.24V to 10V 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 specification 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. 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 LM4040 and LM4041, TJMAX = 125°C, and the typical thermal resistance (θJA), when board mounted, is 326°C/W for the SOT-23 package. The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. The machine model is a 200pF capacitor discharged directly into each pin. Note 2. Note 3. March 2005 3 M9999-031805 LM4040/4041 Micrel, Inc. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. The grades C and D designate initial Reverse Breakdown Voltage tolerance of ±0.5% and ±1.0 respectively. Symbol Parameter Conditions (Note 5) IR = 100µA Typical Limits 2.500 ±12 ±29 45 60 65 ±100 ±25 ±49 65 70 ±150 LM4040CIM3 (Note 6) Limits LM4040DIM3 (Limit) (Note 6) Units LM4040-2.5 Electrical Characteristics (Note 4) VR Reverse Breakdown Voltage Reverse Breakdown Voltage Tolerance (Note 7) Minimum Operating Current V mV (max) mV (max) µA µA (max) µA (max) ppm/°C ppm/°C (max) ppm/°C (max) mV mV (max) mV (max) mV mV (max) mV (max) Ω Ω (max) µVRMS ppm IR = 100µA IRMIN ΔVR/ΔT ΔVR/ΔIR Average Reverse Breakdown Voltage Temperature Coefficient Reverse Breakdown Voltage Change with Operating Current Change IRMIN ≤ IR 1mA 1mA ≤ IR 15mA IR = 10mA IR = 1mA IR = 100µA ±20 ±15 ±15 0.3 0.8 1.0 6.0 8.0 0.9 1.0 1.2 8.0 10.0 1.1 2.5 ZR eN ΔVR Reverse Dynamic Impedance Wideband Noise Reverse Breakdown Voltage Long Term Stability IR = 100µA 10Hz ≤ f ≤ 10kHz t = 1000hrs T = 25°C ±0.1°C IR = 100µA IR = 1mA, f = 120Hz IAC = 0.1 IR 0.3 35 120 Note 4. Note 5. Note 6. Note 7. Specification for packaged product only. Typicals are at TJ = 25°C and represent most likely parametric norm. Limits are 100% production tested at 25°C. Limits over temperature are guaranteed through correlation using Statistical Quality Control (SQL) methods. The boldface (over temperature limit for Reverse Breakdown Voltage Tolerance is defined as the room temperature Reverse Breakdown Voltage Tolerance ±[(ΔVR/ΔT)(65°C)(VR)]. ΔVR/ΔT is the VR temperature coefficient, 65°C is the temperature range from –40°C to the reference point of 25°C, and VR is the reverse breakdown voltage. The total over temperature tolerance for the different grades follows: C-grade: ±1.15% = ±0.5% ±100ppm/°C × 65°C D-grade: ±1.98% = ±1.0% ±150ppm/°C × 65°C Example: The C-grade LM4040-2.5 has an over temperature Reverse Breakdown Voltage tolerance of ±2.5 × 1.15% = ±29mV. M9999-031805 4 March 2005 LM4040/4041 Micrel, Inc. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. The grades C and D designate initial Reverse Breakdown Voltage tolerance of ±0.5% and ± 1.0% respectively. Symbol Parameter Conditions Typical (Note 5) (Note 6) 4.096 ±20 ±47 50 68 73 ±100 ±41 ±81 73 78 ±150 LM4040CIM3 Limits (Note 6) LM4040DIM3 Limits Units (Limits) V mV (max) mV (max) µA µA (max) µA (max) ppm/°C ppm/°C (max) ppm/°C (max) mV mV (max) mV (max) mV mV (max) mV (max) Ω Ω (max) µVRMS ppm LM4040-4.1 Electrical Characteristics (Note 4) VR Reverse Breakdown Voltage Reverse Breakdown Voltage Tolerance (Note 7) Minimum Operating Current IR = 100µA IR = 100µA IRMIN ΔVR/ΔT ΔVR/ΔIR Average Reverse Breakdown Voltage Temperature Coefficient Reverse Breakdown Voltage Change with Operating Current Change IRMIN ≤ IR 1mA 1mA ≤ IR 15mA IR = 10mA IR = 1mA IR = 100µA ±30 ±20 ±20 0.5 0.9 1.2 7.0 10.0 1.0 1.2 1.5 9.0 13.0 1.3 3.0 ZR eN ΔVR Reverse Dynamic Impedance Wideband Noise Reverse Breakdown Voltage Long Term Stability IR = 100µA 10Hz ≤ f ≤ 10kHz t = 1000hrs T = 25°C ±0.1°C IR = 100µA IR = 1mA, f = 120Hz IAC = 0.1 IR 0.5 80 120 Note 4. Note 5. Note 6. Note 7. Specification for packaged product only. Typicals are at TJ = 25°C and represent most likely parametric norm. Limits are 100% production tested at 25°C. Limits over temperature are guaranteed through correlation using Statistical Quality Control (SQL) methods. The boldface (over temperature limit for Reverse Breakdown Voltage Tolerance is defined as the room temperature Reverse Breakdown Voltage Tolerance ±[(ΔVR/ΔT)(65°C)(VR)]. ΔVR/ΔT is the VR temperature coefficient, 65°C is the temperature range from –40°C to the reference point of 25°C, and VR is the reverse breakdown voltage. The total over temperature tolerance for the different grades follows: C-grade: ±1.15% = ±0.5% ±100ppm/°C × 65°C D-grade: ±1.98% = ±1.0% ±150ppm/°C × 65°C Example: The C-grade LM4040-2.5 has an over temperature Reverse Breakdown Voltage tolerance of ±2.5 × 1.15% = ±29mV. March 2005 5 M9999-031805 LM4040/4041 Micrel, Inc. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. The grades C and D designate initial Reverse Breakdown Voltage tolerance of ±0.5% and ± 1.0% respectively. Symbol Parameter Conditions Typical (Note 5) (Note 6) 5.000 ±25 ±58 54 74 80 ±100 ±50 ±99 79 85 ±150 LM4040CIM3 Limits (Note 6) LM4040DIM3 Limits Units (Limits) V mV (max) mV (max) µA µA (max) µA (max) ppm/°C ppm/°C (max) ppm/°C (max) mV mV (max) mV (max) mV mV (max) mV (max) Ω Ω (max) µVRMS ppm LM4040-5.0 Electrical Characteristics (Note 4) VR Reverse Breakdown Voltage Reverse Breakdown Voltage Tolerance (Note 7) Minimum Operating Current IR = 100µA IR = 100µA IRMIN ΔVR/ΔT ΔVR/ΔIR Average Reverse Breakdown Voltage Temperature Coefficient Reverse Breakdown Voltage Change with Operating Current Change IRMIN ≤ IR 1mA 1mA ≤ IR 15mA IR = 10mA IR = 1mA IR = 100µA ±30 ±20 ±20 0.5 1.0 1.4 8.0 12.0 1.1 1.3 1.8 10.0 15.0 1.5 3.5 ZR eN ΔVR Reverse Dynamic Impedance Wideband Noise Reverse Breakdown Voltage Long Term Stability IR = 100µA 10Hz ≤ f ≤ 10kHz t = 1000hrs T = 25°C ±0.1°C IR = 100µA IR = 1mA, f = 120Hz IAC = 0.1 IR 0.5 80 120 Note 4. Note 5. Note 6. Note 7. Specification for packaged product only. Typicals are at TJ = 25°C and represent most likely parametric norm. Limits are 100% production tested at 25°C. Limits over temperature are guaranteed through correlation using Statistical Quality Control (SQL) methods. The boldface (over temperature limit for Reverse Breakdown Voltage Tolerance is defined as the room temperature Reverse Breakdown Voltage Tolerance ±[(ΔVR/ΔT)(65°C)(VR)]. ΔVR/ΔT is the VR temperature coefficient, 65°C is the temperature range from –40°C to the reference point of 25°C, and VR is the reverse breakdown voltage. The total over temperature tolerance for the different grades follows: C-grade: ±1.15% = ±0.5% ±100ppm/°C × 65°C D-grade: ±1.98% = ±1.0% ±150ppm/°C × 65°C Example: The C-grade LM4040-2.5 has an over temperature Reverse Breakdown Voltage tolerance of ±2.5 × 1.15% = ±29mV. M9999-031805 6 March 2005 LM4040/4041 Micrel, Inc. LM4040 Typical Characteristics RS VIN 1Hz rate LM4040 VR Test Circuit March 2005 7 M9999-031805 LM4040/4041 Micrel, Inc. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. The grades C and D designate initial Reverse Breakdown Voltage tolerance of ±0.5% and ± 1.0%, respectively. Symbol Parameter Conditions (Note 5) IR = 100µA Typical LM4041CIM3 Limits (Note 6) ±6 ±14 45 60 65 ±100 (Limit) Units LM4041-1.2 Electrical Characteristics (Note 4) VR Reverse Breakdown Voltage Reverse Breakdown Voltage Tolerance (Note 7) Minimum Operating Current 1.225 V mV (max) mV (max) µA µA (max) µA (max) ppm/°C ppm/°C (max) ppm/°C (max) mV mV (max) mV (max) mV mV (max) mV (max) Ω Ω (max) µVRMS ppm IR = 100µA IRMIN ΔVR/ΔT ΔVR/ΔIR Average Reverse Breakdown Voltage Temperature Coefficient Reverse Breakdown Voltage Change with Operating Current Change IRMIN ≤ IR 1mA 1mA ≤ IR 15mA IR = 10mA IR = 1mA IR = 100µA ±20 ±15 ±15 0.7 1.5 2.0 6.0 8.0 1.5 4.0 ZR eN ΔVR Reverse Dynamic Impedance Wideband Noise Reverse Breakdown Voltage Long Term Stability IR = 100µA 10Hz ≤ f ≤ 10kHz t = 1000hrs T = 25°C ±0.1°C IR = 100µA IR = 1mA, f = 120Hz IAC = 0.1 IR 0.5 20 120 Note 4. Note 5. Note 6. Note 7. Specification for packaged product only. Typicals are at TJ = 25°C and represent most likely parametric norm. Limits are 100% production tested at 25°C. Limits over temperature are guaranteed through correlation using Statistical Quality Control (SQL) methods. The boldface (over temperature limit for Reverse Breakdown Voltage Tolerance is defined as the room temperature Reverse Breakdown Voltage Tolerance ±[(ΔVR/ΔT)(65°C)(VR)]. ΔVR/ΔT is the VR temperature coefficient, 65°C is the temperature range from –40°C to the reference point of 25°C, and VR is the reverse breakdown voltage. The total over temperature tolerance for the different grades follows: C-grade: ±1.15% = ±0.5% ±100ppm/°C × 65°C D-grade: ±1.98% = ±1.0% ±150ppm/°C × 65°C Example: The C-grade LM4040-2.5 has an over temperature Reverse Breakdown Voltage tolerance of ±2.5 × 1.15% = ±29mV. M9999-031805 8 March 2005 LM4040/4041 Micrel, Inc. Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C. The grades C and D designate initial Reverse Breakdown Voltage tolerance of ±0.5% and ± 1.0%, respectively. Symbol VR Parameter Reverse Breakdown Voltage Reverse Breakdown Voltage Tolerance (Note 7) Minimum Operating Current Conditions IR = 100µA 45 IR = 100µA Typical (Note 5) 1.225 ±12 ±24 65 70 ±150 LM4041DIM3 Limits (Note 6) Units (Limit) V mV (max) mV (max) µA µA (max) µA (max) ppm/°C ppm/°C (max) ppm/°C (max) mV mV (max) mV (max) mV mV (max) mV (max) Ω Ω (max) µVRMS ppm LM4041-1.2 Electrical Characteristics (Note 4) IRMIN ΔVR/ΔT ΔVR/ΔIR Average Reverse Breakdown Voltage Temperature Coefficient Reverse Breakdown Voltage Change with Operating Current Change IRMIN ≤ IR 1mA 1mA ≤ IR 15mA IR = 10mA IR = 1mA IR = 100µA ±20 ±15 ±15 0.7 2.0 2.5 8.0 10.0 2.0 2.5 ZR eN ΔVR Reverse Dynamic Impedance Wideband Noise Reverse Breakdown Voltage Long Term Stability IR = 100µA 10Hz ≤ f ≤ 10kHz t = 1000hrs T = 25°C ±0.1°C IR = 100µA IR = 1mA, f = 120Hz IAC = 0.1 IR 0.5 20 120 Note 4. Note 5. Note 6. Note 7. Specification for packaged product only. Typicals are at TJ = 25°C and represent most likely parametric norm. Limits are 100% production tested at 25°C. Limits over temperature are guaranteed through correlation using Statistical Quality Control (SQL) methods. The boldface (over temperature limit for Reverse Breakdown Voltage Tolerance is defined as the room temperature Reverse Breakdown Voltage Tolerance ±[(ΔVR/ΔT)(65°C)(VR)]. ΔVR/ΔT is the VR temperature coefficient, 65°C is the temperature range from –40°C to the reference point of 25°C, and VR is the reverse breakdown voltage. The total over temperature tolerance for the different grades follows: C-grade: ±1.15% = ±0.5% ±100ppm/°C × 65°C D-grade: ±1.98% = ±1.0% ±150ppm/°C × 65°C Example: The C-grade LM4040-2.5 has an over temperature Reverse Breakdown Voltage tolerance of ±2.5 × 1.15% = ±29mV. March 2005 9 M9999-031805 LM4040/4041 Micrel, Inc. LM4041-Adjustable Electrical Characteristics (Note 4) Boldface limits apply for TA = TJ = TMIN to TMAX; all other limits TJ = 25°C unless otherwise specified (SOT-23, see Note 8), IRMIN ≤ IR < 12mA, VREF ≤ VOUT ≤ 10V. The grades C and D designate initial Reverse Breakdown Voltage tolerance of ±0.5% and ±1%, respectively for VOUT = 5V. Symbol Parameter Conditions (Note 5) IR = 100µA VOUT = 5V IR = 100µA 45 Typical Limits 1.233 ±6.2 ±14 60 65 1.5 2.0 ±12 ±24 65 70 2.0 2.5 LM4041CIM3 Limits (Note 6) LM4041DIM3 (Limit) (Note 6) Units VREF Reference Breakdown Voltage Reference Breakdown Voltage Tolerance (Note 9) V mV (max) mV (max) µA 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) ppm/°C ppm/°C (max) ppm/°C (max) IRMIN ΔVREF /ΔIR Minimum Operating Current Reference Voltage Change with Operating Current Change IRMIN ≤ IR 1mA SOT-23: VOUT ≥ 1.6V (Note 8) 1mA ≤ IR 15mA SOT-23: VOUT ≥ 1.6V (Note 8) 0.7 2 4 6 6 8 ΔVREF /ΔVO IFB ΔVREF /ΔT Reference Voltage Change with Output Voltage Change Feedback Current IR = 1mA –1.55 –2.0 –2.5 100 120 ±100 –2.5 –3.0 150 200 ±150 60 Average Reference Voltage Temperature Coefficient (Note 9) Dynamic Output Impedance ZOUT eN ΔVREF Wideband Noise Reference Voltage Long Term Stability IR = 1mA, f = 120Hz IAC = 0.1 IR VOUT = VREF VOUT = 10V IR = 100µA 10Hz ≤ f ≤ 10kHz t = 1000hrs T = 25°C ±0.1°C IR = 100µA VOUT = 5V IR = 10mA IR = 1mA IR = 100µA ±20 ±15 ±15 0.3 2 20 120 Ω Ω (max) µVRMS ppm Note 4. Note 5. Note 6. Note 7. Specification for packaged product only. Typicals are at TJ = 25°C and represent most likely parametric norm. Limits are 100% production tested at 25°C. Limits over temperature are guaranteed through correlation using Statistical Quality Control (SQL) methods. The boldface (over temperature limit for Reverse Breakdown Voltage Tolerance is defined as the room temperature Reverse Breakdown Voltage Tolerance ±[(ΔVR/ΔT)(65°C)(VR)]. ΔVR/ΔT is the VR temperature coefficient, 65°C is the temperature range from –40°C to the reference point of 25°C, and VR is the reverse breakdown voltage. The total over temperature tolerance for the different grades follows: C-grade: ±1.15% = ±0.5% ±100ppm/°C × 65°C D-grade: ±1.98% = ±1.0% ±150ppm/°C × 65°C Example: The C-grade LM4040-2.5 has an over temperature Reverse Breakdown Voltage tolerance of ±2.5 × 1.15% = ±29mV. Note 8. Note 9. When VOUT ≤ 1.6V, the LM4041-ADJ 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. Reference voltage and temperature coefficient will change with output voltage. See “Typical Performance Characteristics” curves. M9999-031805 10 March 2005 LM4040/4041 Micrel, Inc. LM4041 Typical Characteristics RS 30k VIN 1Hz rate V LM4041-1. 2 R Test Circuit March 2005 11 M9999-031805 LM4040/4041 Micrel, Inc. LM4041 Typical Characteristics IR (+) LM4041-ADJ FB V OUT ( – ) 2V / step V † Reverse Characteristics Test Circuit IR + CL 120k FB – * Output Impedance vs. Freq. Test Circuit + 15V 5.1k INPUT 100k FB (+) LM4041-ADJ VOUT (–) * Output impedance measurement.. † ‡ Reverse characteristics measurement. Large signal response measurement. ‡ Large Signal Response Test Circuit 12 March 2005 M9999-031805 LM4040/4041 Micrel, Inc. Adjustable Regulator The LM4041-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 is found using the equation: (1) VO = VREF [ (R2/R1) + 1 ] where VO is the desired output voltage. The actual value of the internal VREF is a function of VO. The “corrected” VREF is determined by: (2) VREF´ = VO (ΔVREF / ΔVO) + VY where VO is the desired output voltage. ΔVREF / ΔVO is found in the “Electrical Characteristics” and is typically –1.3mV/V and VY is equal to 1.233V. Replace the value of VREF in equation (1) with the value VREF found using equation (2). Note that actual output voltage can deviate from that predicted using the typical ΔVREF / ΔVO in equation (2); for Cgrade parts, the worst-case ΔVREF / ΔVO is –2.5mV/V and VY = 1.248V. The following example shows the difference in output voltage resulting from the typical and worst case values of ΔVREF / ΔVO. Let VO = +9V. Using the typical values of ΔVREF /ΔVO , VREF is 1.223V. Choosing a value of R1 = 10kΩ, R2 = 63.272kΩ. Using the worst case ΔVREF / ΔVO for the C-grade and Dgrade parts, the output voltage is actually 8.965V and 8.946V respectively. This results in possible errors as large as 0.39% for the C-grade parts and 0.59% for the D-grade parts. Once again, resistor values found using the typical value of ΔVREF / ΔVO will work in most cases, requiring no further adjustment. Applications Information The stable operation of the LM4040 and LM4041 references requires an external capacitor greater than 10nF connected between the (+) and (–) pins. Bypass capacitors with values between 100pF and 10nF have been found to cause the devices to exhibit instabilities. Schottky Diode LM4040-x.x and LM4041-1.2 in the SOT-23 package have a parasitic Schottky diode between pin 2 (–) and pin 3 (die attach interface connect). Pin 3 of the SOT-23 package must float or be connected to pin 2. LM4041-ADJs use pin 3 as the (–) output. Conventional Shunt Regulator In a conventional shunt regulator application (see Figure 1), an external series resistor (RS) is connected between the supply voltage and the LM4040-x.x or LM4041-1.2 reference. RS determines the current that flows through the load (IL) and the reference (IQ). Since load current and supply voltage may vary, RS should be small enough to supply at least the minimum acceptable IQ to the reference 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 LM4040-x.x is less than 15mA, and the current flowing through the LM4041-1.2 or LM4041-ADJ is less than 12mA. RS is determined by the supply voltage (VS), the load and operating current, (IL and IQ), and the reference’s reverse breakdown voltage (VR): Rs = (Vs – VR) / (IL + IQ) Typical Application Circuits + FB 120k LM4041-ADJ D1 – λ < –12V R3 LED ON 200 –5V R1 λ D1 + FB R1 120k R2 1M R2 1M LM4041– ADJ > –12V R3 LED ON 330 –5V Figure 3. Voltage Level Detector Figure 4. Voltage Level Detector March 2005 13 M9999-031805 LM4040/4041 VIN I R2 50A R1 VOUT D1 1N914 D2 1N914 + LM4041-ADJ – FB R3 240k R4 240k LM4041-ADJ + VIN I R1 Micrel, Inc. FB – D1 1N457 VOUT R2 D2 510k – 1N457 FB LM4041-ADJ + R3 510k Figure 5. Fast Positive Clamp 2.4V + ∆VD1 Figure 6. Bidirectional Clamp ±2.4V VIN I R1 R2 390k R3 500k FB R4 390k D1 1N457 VOUT D2 1N457 LM4041-ADJ LM4041-ADJ I VIN R1 VOUT + – R2 330k R3 1M D2 1N457 FB – + FB + LM4041-ADJ – FB – + LM4041-ADJ D1 1N457 R4 330k Figure 7. Bidirectional Adjustable Clamp ±18V to ±2.4V Figure 8. Bidirectional Adjustable Clamp ±2.4 to ±6V 0 to 20mA R1 390Ω ± 2% D1* + 5V + FB λ LM4041-ADJ – 1 2 N.C. I THRESHOLD = 3 4N28 6 5 4 N.C. R2 470k CMOS 1N4002 D2 1.24V 5A + = 3.2m A R1 4N28 GAIN * D1 can be any LED, VF = 1.5V to 2.2V at 3mA. D1 may act as an indicator. D1 will be on if ITHRESHOLD falls below the threshold current, except with I = O. Figure 9. Floating Current Detector M9999-031805 14 March 2005 LM4040/4041 Micrel, Inc. +15V R1 FB 2N2905 R2 120k 2N 3964 + LM4041-ADJ – 1A < IOUT = 100mA 1.24V I OUT = R1 Figure 10. Current Source 0 to 20 mA R1 332Ω ±1% D2 1N4002 +5V + FB 1N914 LM4041-ADJ – 2N2222 R2 22k D1* λ R3 100k 1 2 4N28 6 5 4 3 N.C. 1.24V = 3.7mA ± 2% I THRESHOLD = R1 R4 10M CMOS * D1 can be any LED, VF = 1.5V to 2.2V at 3mA. D1 may act as an indicator. D1 will be on if ITHRESHOLD falls below the threshold current, except with I = O. Figure 11. Precision Floating Current Detector March 2005 15 M9999-031805 LM4040/4041 Micrel, Inc. Package Information SOT-23 (M3) MICREL INC. TEL + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB http://www.micrel.com 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2004 Micrel Incorporated M9999-031805 16 March 2005