REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com 4 ppm/°C, 100 μA SOT23-6 SERIES VOLTAGE REFERENCES Check for Samples: REF3212-EP, REF3220-EP, REF3225-EP, REF3230-EP, REF3233-EP, REF3240-EP FEATURES APPLICATIONS • • • • • 1 • • • • • Excellent Specified Drift Performance: – 7ppm/°C (Max) at 0°C to 125°C – 20ppm/°C (Max) at –40°C to 125°C – 40ppm/°C (Max) at –55°C to 125°C Microsize Package: SOT23-6 High Output Current: ±10 mA High Accuracy: 0.01% Low Quiescent Current: 100 μA Low Dropout: 5 mV Portable Equipment Data Acquisition Systems Medical Equipment Test Equipment GND_F 1 GND_S 2 ENABLE 3 REF3212 REF3220 REF3225 REF3230 REF3233 REF3240 6 OUT_F 5 OUT_S 4 IN SUPPORTS DEFENSE, AEROSPACE, AND MEDICAL APPLICATIONS • • • • • • • (1) Controlled Baseline One Assembly/Test Site One Fabrication Site Available in Military (–55°C/125°C) Temperature Range (1) Extended Product Life Cycle Extended Product-Change Notification Product Traceability Additional temperature ranges are available - contact factory TEMPERATURE DRIFT (0_C to +125_C) DROPOUT VOLTAGE vs LOAD CURRENT 160 +125_C Population Dropout Voltage (mV) 140 +25_ C 120 100 −40_C 80 60 40 20 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 Drift (ppm/_C) −15 −10 −5 0 5 10 15 Load Current (mA) 1 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2006–2011, Texas Instruments Incorporated REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com DESCRIPTION The REF32xx is a very low drift, micropower, low-dropout, precision voltage reference family available in the tiny SOT23-6 package. The small size and low power consumption (120 μA max) of the REF32xx make it ideal for portable and battery-powered applications. This reference is stable with most capacitive loads. The REF32xx can be operated from a supply as low as 5 mV above the output voltage, under no load conditions. All models are specified for the wide temperature range of –55°C to 125°C. AVAILABLE OUTPUT VOLTAGES PRODUCT VOLTAGE REF3212 1.25 V REF3220 2.048 V REF3225 2.5 V REF3230 3V REF3233 3.3 V REF3240 4.096 V Table 1. PACKAGE/ORDERING INFORMATION (1) (1) (2) 2 PRODUCT OUTPUT VOLTAGE PACKAGE-LEAD PACKAGE DESIGNATOR (2) PACKAGE MARKING REF3212AMDBVREP 1.25 V SOT23-6 DBV R3AM REF3220AMDBVREP 2.048 V SOT23-6 DBV R3BM REF3225AMDBVREP 2.5 V SOT23-6 DBV R3CM REF3230AMDBVREP 3V SOT23-6 DBV R3DM REF3233AMDBVREP 3.3 V SOT23-6 DBV R3EM REF3240AMDBVREP 4.096 V SOT23-6 DBV R3FM For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI website at www.ti.com. Package drawings, thermal data, and symbolization are available at www.ti.com/packaging. Submit Documentation Feedback Copyright © 2006–2011, Texas Instruments Incorporated Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. Figure 1. PIN CONFIGURATION SOT23-6 (TOP VIEW) 1 GND_S 2 ENABLE 3 R3 2 x A. GND_F 6 OUT_F 5 OUT_S 4 IN The location of pin 1 on the REF32xx is determined by orienting the package marking as shown. PIN DESCRIPTIONS PIN NAME NO. FUNCTION ENABLE 3 Digital input DESCRIPTION GND_F 1 Analog output GND_S 2 Analog input Ground sense at the load IN 4 Analog input Positive supply voltage OUT_F 6 Analog output Output of Reference Voltage OUT_S 5 Analog input Sense connection at the load This pin enables and disables the device Ground connection of the device Absolute Maximum Ratings (1) MIN Input voltage Output short-circuit Storage temperature range Junction temperature (2) V –55 125 °C –65 (2) °C 150 °C 150 Human-Body Model 4 Charged-Device Model 1 Machine Model (1) UNIT 7.5 Continuous Operating temperature range ESD rating MAX 400 kV V Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied. Long-term high-temperature storage and/or extended use at maximum recommended operating conditions may result in a reduction of overall device life. See http://www.ti.com/ep_quality for additional information on enhanced plastic packaging. Copyright © 2006–2011, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP 3 REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com Electrical Characteristics Boldface limits apply over the listed temperature range. TA = 25°C, ILOAD = 0 mA, and VIN = 5 V (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Output voltage 1.2475 1.25 1.2525 V Initial accuracy –0.2 0.01 0.2 % REF3212 (1.25 V) VOUT Noise Output voltage noise f = 0.1 Hz to 10 Hz 17 μVPP Voltage noise f = 10 Hz to 10 kHz 24 μVRMS REF3220 (2.048 V) Output voltage VOUT Initial accuracy Output voltage noise Noise 2.044 2.048 2.052 V –0.2 0.01 0.2 % f = 0.1 Hz to 10 Hz 27 μVPP Voltage noise f = 10 Hz to 10 kHz 39 μVRMS REF3225 (2.5 V) VOUT Noise Output voltage Initial accuracy 2.495 2.5 2.505 –0.2 0.01 0.2 V % Output voltage noise f = 0.1 Hz to 10 Hz 33 μVPP Voltage noise f = 10 Hz to 10 kHz 48 μVRMS REF3230 (3 V) VOUT Noise Output voltage 2.994 3 3.006 V Initial accuracy –0.2 0.01 0.2 % Output voltage noise f = 0.1 Hz to 10 Hz 39 μVPP Voltage noise f = 10 Hz to 10 kHz 57 μVRMS REF3233 (3.3 V) VOUT Noise Output voltage Initial accuracy 3.293 3.3 3.307 –0.2 0.01 0.2 V % Output voltage noise f = 0.1 Hz to 10 Hz 43 μVPP Voltage noise f = 10 Hz to 10 kHz 63 μVRMS REF3240 (4.096 V) VOUT Noise Output voltage 4.088 4.096 4.104 V Initial accuracy –0.2 0.01 0.2 % Output voltage noise f = 0.1 Hz to 10 Hz 53 μVPP Voltage noise f = 10 Hz to 10 kHz 78 μVRMS REF3212/REF3220/REF3225/REF3230/REF3233/REF3240 dVOUT/dT Output voltage temperature drift 0 tp 1000 h Line regulation VOUT + 0.05 (1) ≤ VIN ≤ 5.5 V –65 Sourcing 0 mA < ILOAD < 10 mA, VIN = VOUT + 250 mV (1) Sinking –10 mA < ILOAD < 0 mA, VIN = VOUT + 100 mV (1) Load regulation (2) dT Thermal hysteresis (3) VIN – VOUT Dropout voltage (1) 4 –55°C ≤ TA ≤ 125°C Long-term stability dVOUT/ dILOAD (1) (2) (3) TA = 25°C 4 7 10.5 40 55 ppm 15 65 –40 3 40 –60 20 60 First cycle 100 Additional cycles 25 25°C ≤ TA ≤ +125°C 5 ppm/°C ppm/V μV/mA ppm 50 mV The minimum supply voltage for the REF3212 is 1.8 V. Load regulation is using force and sense lines; see the Load Regulation section for more information. Thermal hysteresis procedure is explained in more detail in the Applications Information section. Submit Documentation Feedback Copyright © 2006–2011, Texas Instruments Incorporated Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com Electrical Characteristics (continued) Boldface limits apply over the listed temperature range. TA = 25°C, ILOAD = 0 mA, and VIN = 5 V (unless otherwise noted) PARAMETER ILOAD Output current ISC Short-circuit current TEST CONDITIONS MAX 10 50 Sinking 40 0.1% at VIN = 5 V with CL = 0 Reference is active UNIT mA mA μs 60 Reference in shutdown mode Enable/shutdown (4) VH TYP –10 Sourcing Turn-on settling time VL MIN VIN = VOUT + 250 mV (1) 0 0.7 1.5 VIN VOUT + 0.05 (1) 5.5 V V VIN Power supply Voltage IL = 0 IQ Power supply Current IL = 0, ENABLE > 1.5 V 100 120 μA –55°C ≤ TA ≤ 125°C 115 135 μA ENABLE < 0.7 V 0.1 1 μA IS Overtemperature shutdown Temperature range θJA (4) Specified –55 125 Operating –55 125 Storage –65 Thermal resistance, SOT23-6 °C 150 200 °C/W If the rise time of the input voltage is less than or equal to 2ms, the ENABLE and IN pins can be tied together. For rise times greater than 2ms, see the Supply Voltage section. Figure 2. Operating Life Derating Chart 10000.00 Years Estimated Life 1000.00 Wirebond Voiding Fail Mode 100.00 10.00 1.00 0.10 80 Electromigration Fail Mode 90 100 110 120 130 140 150 160 Continuuous TJ (5C) A. See Datasheet for Absolute Maximum and Minimum Recommended Operating Conditions. B. Silicon Operating Life Design Goal is 10 years at 105°C Junction Temperature (does not include package interconnect life). C. Enhanced Plastic Product Disclaimer Applies. Copyright © 2006–2011, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP 5 REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com TYPICAL CHARACTERISTICS TA = 25°C, ILOAD = 0 mA, VIN = 5 V power supply, REF3225 is used for typical characteristics (unless otherwise noted) TEMPERATURE DRIFT (−40_ C to +125_ C) Population Population TEMPERATURE DRIFT (0_C to +125_C) 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Drift (ppm/_C) Drift (ppm/_C) OUTPUT VOLTAGE ACCURACY vs TEMPERATURE DROPOUT VOLTAGE vs LOAD CURRENT 0.12 160 0.08 Dropout Voltage (mV) Output Voltage Accuracy (%) +125_C 140 0.04 0 −0.04 −0.08 −0.12 −50 +25_ C 120 100 −40_C 80 60 40 20 0 −25 0 +25 +50 +75 +100 +125 −15 −10 Temperature (°C ) −5 0 5 10 15 Load Current (mA) QUIESCENT CURRENT vs TEMPERATURE POWER−SUPPLY REJECTION RATIO vs FREQUENCY 100 130 90 80 70 110 PSRR (dB) Quiescent Current (µA) 120 100 50 40 90 30 80 70 20 10 −50 −25 0 +25 +50 Temperature (_ C) 6 60 Submit Documentation Feedback +75 +100 +125 1 10 100 1k 10k 100k Frequency (Hz) Copyright © 2006–2011, Texas Instruments Incorporated Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) TA = 25°C, ILOAD = 0 mA, VIN = 5 V power supply, REF3225 is used for typical characteristics (unless otherwise noted) OUTPUT VOLTAGE vs LOAD CURRENT 1.2525 2.505 1.2520 2.504 1.2515 2.503 Output Voltage (V) 1.2510 1.2505 +125_C 1.2500 +25_ C 1.2495 1.2490 −40_ C 1.2485 2.502 2.501 +125_ C 2.500 +25_ C 2.499 2.498 −40_ C 2.497 2.496 1.2480 2.495 1.2475 2 2.5 3 3.5 4 4.5 −15 5 −10 −5 Input Voltage (V) 0 5 10 15 Load Current (mA) 0.1Hz TO 10Hz NOISE 0.20 0.16 0.12 0.08 0.04 −0.08 −0.12 −0.20 400ms/div −0.16 10µV/div Population OUTPUT VOLTAGE INITIAL ACCURACY 0 1.5 −0.04 Output Voltage (V) OUTPUT VOLTAGE vs INPUT VOLTAGE (REF3212) Output Accuracy (%) STEP RESPONSE CL = 0pF, 5V STARTUP STEP RESPONSE CL = 1µF VIN VIN 1V/div 1V/div VOUT VOUT 10µs/div Copyright © 2006–2011, Texas Instruments Incorporated 100µs/div Submit Documentation Feedback Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP 7 REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) TA = 25°C, ILOAD = 0 mA, VIN = 5 V power supply, REF3225 is used for typical characteristics (unless otherwise noted) 500mV/div LINE TRANSIENT CL = 10µF VIN VIN VOUT 20mV/div 20mV/div 500mV/div LINE TRANSIENT CL = 0pF ILOAD VOUT 20µs/div 100µs/div LOAD TRANSIENT CL = 0pF, ±10mA OUTPUT PULSE LOAD TRANSIENT CL = 1µF, ±10mA OUTPUT PULSE +10mA ILOAD +10mA +10mA +10mA −10mA −10mA 50mV/div 200mV/div VOUT ILOAD VOUT 40µs/div 40µs/div LOAD TRANSIENT CL = 0pF, ±1mA OUTPUT PULSE LOAD TRANSIENT CL = 1µF, ±1mA OUTPUT PULSE ILOAD +1mA +1mA −1mA +1mA +1mA −1mA 20mV/div 100mV/div VOUT 40µs/div 8 Submit Documentation Feedback VOUT 40µs/div Copyright © 2006–2011, Texas Instruments Incorporated Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) TA = 25°C, ILOAD = 0 mA, VIN = 5 V power supply, REF3225 is used for typical characteristics (unless otherwise noted) LONG−TERM STABILITY (32 Units) Output Voltage Stability (ppm) 200 150 100 50 0 −50 −100 −150 −200 0 200 400 600 800 1000 1200 Time (Hours) Copyright © 2006–2011, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP 9 REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com THEORY OF OPERATION The REF32xx is a family of CMOS, precision bandgap voltage references. Figure 3 shows the basic bandgap topology. Transistors Q1 and Q2 are biased so that the current density of Q1 is greater than that of Q2. The difference of the two base-emitter voltages (Vbe1 – Vbe2) has a positive temperature coefficient and is forced across resistor R1. This voltage is amplified and added to the base-emitter voltage of Q2, which has a negative temperature coefficient. The resulting output voltage is virtually independent of temperature. VBANDGAP Q1 I + Vbe1 - R1 + Vbe2 N Q2 Figure 3. Simplified Schematic of Bandgap Reference 10 Submit Documentation Feedback Copyright © 2006–2011, Texas Instruments Incorporated Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com APPLICATION INFORMATION The REF32xx does not require a load capacitor and is stable with most capacitive loads, see Load Capacitance Guidelines. Figure 4 shows typical connections required for operation of the REF32xx. A supply bypass capacitor of 0.47 μF is recommended. 0.47 µF +5 V 2 3 +2.5 V 6 R 3 CM 1 5 4 Figure 4. Typical Operating Connections for the REF3225 Supply Voltage The REF32xx family of references features an extremely low dropout voltage. With the exception of the REF3212, which has a minimum supply requirement of 1.8 V, these references can be operated with a supply of only 5 mV above the output voltage in an unloaded condition. For loaded conditions, a typical dropout voltage versus load is shown in the Typical Characteristic curves. The REF32xx also features a low quiescent current of 100 μA, with a maximum quiescent current over temperature of just 135 μA. The quiescent current typically changes less than 2 μA over the entire supply range, as shown in Figure 5. 110 Quiescent Current (µA) 108 106 104 102 100 98 96 94 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Power Supply (V) Figure 5. Supply Current vs Supply Voltage Supply voltages below the specified levels can cause the REF32xx to momentarily draw currents greater than the typical quiescent current. This momentary current draw can be prevented by using a power supply with a fast rising edge and low output impedance. For optimal startup when the IN pin and ENABLE pin are tied together, keep the input voltage rise time less than or equal to 2ms. For rise times greater than 2ms, the ENABLE pin must be kept below 0.7V until the voltage at the IN pin has reached the minimum operating voltage. One way to control the voltage at the ENABLE pin is with an additional RC filter, such as that shown in Figure 6. The RC filter must hold the voltage at the ENABLE pin below the threshold voltage until the voltage at the input pin has reached the minimum operating voltage. Copyright © 2006–2011, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP 11 REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com 1 6 2 5 3 4 VREF VIN R1 C1 Figure 6. Application Circuit to Control the REF32xx ENABLE Pin The RC filter in Figure 6 can be used as a starting point for the REF3240. The values for R1 and C1 have been calculated so that the voltage at the ENABLE pin reaches 0.7V after the input voltage has reached 4.15V; Table 2 lists these values. For output voltage options other than 4.096V, the RC filter can be made faster. Table 2. Recommended R1 and C1 Values for the REF3240 RISE TIME R1 VALUE C1 VALUE 2ms 150kΩ 100nF 5ms 150kΩ 220nF 10ms 330kΩ 220nF 20ms 390kΩ 330nF 50ms 680kΩ 470nF 100ms 680kΩ 1000nF In this document, rise time is defined as the time until an exponential input signal reaches 90% of its final voltage. For example, the 2ms value shown in Table 2 is valid for an end value of 5V. If the input voltage has a different shape or the end value is not 5V, then the time until the minimum dropout voltage has been reached should be used to decide if the IN and ENABLE pins can be tied together. Table 3 lists these times. Table 3. Minimum Dropout Voltage Times DEVICE TIME REF3212 0.4ms REF3220 0.5ms REF3225 0.7ms REF3230 0.9ms REF3233 1.0ms REF3240 1.6ms Note that because the leakage current of the EN pin is in the range of a few nA, it can be disregarded in most applications. 12 Submit Documentation Feedback Copyright © 2006–2011, Texas Instruments Incorporated Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com Shutdown The REF32xx can be placed in a low-power mode by pulling the ENABLE/SHUTDOWN pin low. When in shutdown mode the output of the REF32xx becomes a resistive load to ground. The value of the load depends on the model, and ranges from approximately 100 kΩ to 400 kΩ. The ENABLE pin must always be driven to a valid voltage level (VL or VH) as shown in the Electrical Characteristics section of this datasheet. To maintain the low quiescent current (100 μA typ), the ENABLE pin was designed without an internal pull-up resistor. In applications where the shutdown feature will not be used, connecting the ENABLE pin high (to the IN pin) will ensure enabled operation of the device. Thermal Hysteresis Thermal hysteresis for the REF32xx is defined as the change in output voltage after operating the device at 25°C, cycling the device through the specified temperature range, and returning to 25°C. It can be expressed as: ŤVPRE * V Ť POST 106(ppm) V HYST + VNOM (1) Ǔ ǒ Where: VHYST = Thermal hysteresis (in units of ppm) VNOM = The specified output voltage VPRE = Output voltage measured at 25°C pretemperature cycling VPOST = Output voltage measured after the device has been cycled through the specified temperature range of –40°C to 125°C and returned to 25°C Temperature Drift The REF32xx is designed to exhibit minimal drift error, which is defined as the change in output voltage over varying temperature. The drift is calculated using the box method, as described by the following equation: Drift + ǒV V OUT Ǔ * V OUTMIN Temp Range OUTMAX 106(ppm) (2) The REF32xx features a typical drift coefficient of 4 ppm/°C from 0°C to 125°C — the primary temperature range for many applications. For the extended temperature range of –55°C to 125°C, the REF32xx family drift increases to a typical value of 10.5 ppm/°C. Noise Performance Typical 0.1-Hz to 10-Hz voltage noise can be seen in the Typical Characteristic curve, 0.1-Hz to 10-Hz Voltage Noise. The noise voltage of the REF32xx increases with output voltage and operating temperature. Additional filtering can be used to improve output noise levels, although care should be taken to ensure the output impedance does not degrade ac performance. Long-Term Stability Long-term stability refers to the change of the output voltage of a reference over a period of months or years. This effect lessens as time progresses, as is shown by the long-term stability Typical Characteristic curves. The typical drift value for the REF32xx is 55 ppm from 0 to 1000 hours. This parameter is characterized by measuring 30 units at regular intervals for a period of 1000 hours. Copyright © 2006–2011, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP 13 REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com Load Regulation Load regulation is defined as the change in output voltage as a result of changes in load current. The load regulation of the REF32xx is measured using force and sense contacts, as shown in Figure 7. The force and sense lines can be used to effectively eliminate the impact of contact and trace resistance, resulting in accurate voltage at the load. By connecting the force and sense lines at the load, the REF32xx compensates for the contact and trace resistances because it measures and adjusts the voltage actually delivered at the load. Contact and Trace Resistance GND_F GND_S ENABLE 1 6 2 REF32xx 5 3 4 OUT_F OUT_S IN RLOAD 0.47 mF +5 V Figure 7. Accurate Load Regulation of REF32xx The GND_S pin is connected to the internal ground of the device through ESD protection diodes. Because of that connection, the maximum differential voltage between the GND_S and GND_F pins must be kept below 200mV to prevent these dioes from unintentionally turning on. Load Capacitance Guidelines The REF32xx series is designed to be stable with most capacitive loads. Common load capacitance values range between 1 μF and 47 μF. To minimize noise and provide specified performance, all models will benefit from an ESR value above 1 Ω with capacitive loads higher than 10 μF. However, the REF3212 must have an ESR value above 1Ω with capacitive loads higher than 10 μF to avoid oscillation. 14 Submit Documentation Feedback Copyright © 2006–2011, Texas Instruments Incorporated Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com APPLICATION CIRCUITS Negative Reference Voltage For applications requiring a negative and positive reference voltage, the REF32xx and OPA735 can be used to provide a dual-supply reference from a 5-V supply. Figure 8 shows the REF3225 used to provide a 2.5-V supply reference voltage. The low drift performance of the REF32xx complements the low offset voltage and zero drift of the OPA735 to provide an accurate solution for split-supply applications. Care must be taken to match the temperature coefficients of R1 and R2. +5 V 3 4 5 REF3225 2 6 1 +2.5 V R1 10 kW R 2 10 kW +5 V OPA735 -2.5 V -5 V Note: Bypass capacitor is not shown. Figure 8. REF3225 Combined With OPA735 to Create Positive and Negative Reference Voltages Data Acquisition Data acquisition systems often require stable voltage references to maintain accuracy. The REF32xx family features stability and a wide range of voltages suitable for most microcontrollers and data converters. Figure 9, Figure 10, and Figure 11 show basic data acquisition systems. 5 3.3 V 6 3 REF3233 5W VCC V+ 0.47 mF 1 mF to 10 mF 1 mF to 10 mF 0.1 mF VIN + + 1 GND VS ADS7822 VREF 2 4 +In CS -In DOUT Microcontroller GND DCLOCK Figure 9. Basic Data Acquisition System 1 Copyright © 2006–2011, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP 15 REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com 2.5 V Supply 2.5 V 3 5W VIN 4 5 REF3212 6 VOUT = 1.25 V 2 VS ADS8324 VREF VCC 0.1 mF 1 GND 0 V to 1.25 V +In CS -In DOUT + + 1 mF to 10 mF 1 mF to 10 mF Microcontroller GND DCLOCK Figure 10. Basic Data Acquisition System 2 +5 V 2 1 1 kW REF3240 3 4 5 6 VOUT = 4.096 V 10 W 0.1 mF 1 mF 22 mF +5 V 1 kW VIN VREF 10 W ADS8381 THS4031 6800 pF 0.22 mF 500 W -5 V Figure 11. REF3240 Provides an Accurate Reference for Driving the ADS8381 16 Submit Documentation Feedback Copyright © 2006–2011, Texas Instruments Incorporated Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011 www.ti.com Changes from Revision A (April 2007) to Revision B Page • Added Pin Descriptions table ................................................................................................................................................ 3 • Added note to Enable/Shutdown parameter ......................................................................................................................... 5 • Changed the minimum voltage for Enable/Shutdown with reference active from 0.75 x VIN to 1.5 ..................................... 5 • Changed current test condition from 0.75 x VIN to 1.5 V ...................................................................................................... 5 • Added text, two tables and one figure to Supply Voltage section ...................................................................................... 11 • Changed pin 3 in Figure 7 from SHDN to ENABLE (typo) ................................................................................................. 14 • Added paragraph to Load Regulation section .................................................................................................................... 14 Copyright © 2006–2011, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP 17 PACKAGE OPTION ADDENDUM www.ti.com 13-Jun-2012 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) Samples (Requires Login) REF3212AMDBVREP ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI REF3212AMDBVREPG4 ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI REF3220AMDBVREP ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI REF3225AMDBVREP ACTIVE SOT-23 DBV 6 250 TBD Call TI Call TI REF3225AMDBVREPG4 ACTIVE SOT-23 DBV 6 250 TBD Call TI Call TI REF3230AMDBVREP ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI REF3230AMDBVREPG4 ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI REF3233AMDBVREP ACTIVE SOT-23 DBV 6 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR REF3233AMDBVREPG4 ACTIVE SOT-23 DBV 6 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR REF3240AMDBVREP ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI REF3240AMDBVREPG4 ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI V62/07602-01XE ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI V62/07602-02XE ACTIVE SOT-23 DBV 6 250 TBD Call TI Call TI V62/07602-03XE ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI V62/07602-04XE ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI V62/07602-05XE ACTIVE SOT-23 DBV 6 3000 TBD Call TI Call TI V62/07602-06XE ACTIVE SOT-23 DBV 6 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Addendum-Page 1 PACKAGE OPTION ADDENDUM www.ti.com 13-Jun-2012 Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. 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OTHER QUALIFIED VERSIONS OF REF3212-EP, REF3220-EP, REF3225-EP, REF3230-EP, REF3233-EP, REF3240-EP : • Catalog: REF3212, REF3220, REF3225, REF3230, REF3233, REF3240 NOTE: Qualified Version Definitions: • Catalog - TI's standard catalog product Addendum-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. 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