Sample & Buy Product Folder Support & Community Tools & Software Technical Documents Reference Design ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 ATL43x 2.5-V Low Iq Adjustable Precision Shunt Regulator 1 Features 3 Description • • The ATL431 and ATL432 are three-terminal adjustable shunt regulators, with specified thermal stability over applicable automotive, commercial, and industrial temperature ranges. The output voltage can be set to any value between Vref (approximately 2.5 V) and 36 V, with two external resistors. These devices have a typical output impedance of 0.05 Ω. Active output circuitry provides a very sharp turn-on characteristic, making these devices excellent replacements for Zener diodes in many applications, such as onboard regulation, adjustable power supplies, and switching power supplies. 1 • • • • • Adjustable Regulated Output of 2.5 V to 36 V Very-Low Operating Current – IKA(min) = 35 µA (Max) – IREF = 150 nA (Max) Internally Compensated for Stability – Stable With No Capacitive Load Reference Voltage Tolerances at 25°C – 0.5% for ATL43xB – 1% for ATL43xA Typical Temperature Drift – 5 mV (–40°C to 85°C); I Version – 6 mV (–40°C to 125°C); Q Version Extended Cathode Current Range 35 µA to 100 mA Low Output Impedance of 0.3 Ω (Max) 2 Applications • • • • • • Secondary Side Regulation in Flyback SMPSs Industrial, Computing, Consumer, and Portables Adjustable Voltage and Current Referencing Power Management Power Isolation Zener Replacement The ATL43x has > 20x improvement cathode current range over it's TL43x predecessor. It also is stable with a wider range of load capacitance types and values. ATL431 and ATL432 are the exact same parts but with different pinouts and order numbers. The ATL43x is offered in two grades, with initial tolerances (at 25°C) of 0.5%, 1%, for the B and A grade, respectively. In addition, low output drift vs temperature ensures good stability over the entire temperature range. The ATL43xxI devices are characterized for operation from –40°C to 85°C, and the ATL43xxQ devices are characterized for operation from –40°C to 125°C. Device Information(1) PART NUMBER ATL431 ATL432 PACKAGE SOT (3) BODY SIZE (NOM) 2.90 mm × 1.60 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. Simplified Schematic Stability Region for VKA = 15.0 V 2000 VKA Input IKA IKA(PA) Vref 1000 STABLE 100 20 0.0001 0.001 0.01 0.1 CKA(PF) 1 10 D001 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 www.ti.com Table of Contents 1 2 3 4 5 6 7 8 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 3 6.1 6.2 6.3 6.4 6.5 6.6 6.7 3 3 3 4 4 4 5 Absolute Maximum Ratings ..................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics, ATL431Ax, ATL432Ax ..... Electrical Characteristics, ATL431Bx, ATL432Bx ..... Typical Characteristics .............................................. Parameter Measurement Information .................. 9 Detailed Description ............................................ 11 8.1 Overview ................................................................. 11 8.2 Functional Block Diagram ....................................... 11 8.3 Feature Description................................................. 11 8.4 Device Functional Modes........................................ 12 9 Application and Implementation ........................ 13 9.1 Application Information............................................ 13 9.2 Typical Applications ................................................ 14 10 Power Supply Recommendations ..................... 18 11 Layout................................................................... 18 11.1 Layout Guidelines ................................................. 18 11.2 Layout Example .................................................... 18 12 Device and Documentation Support ................. 19 12.1 12.2 12.3 12.4 12.5 Related Links ........................................................ Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 19 19 19 19 19 13 Mechanical, Packaging, and Orderable Information ........................................................... 19 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision B (May 2015) to Revision C • Page Changed ATL432xx status from PREVIEW to PRODUCTION. ............................................................................................. 1 Changes from Revision A (April 2015) to Revision B Page • Changed ATL431AQ, ATL431BI and ATL431BQ status from PREVIEW to PRODUCTION. ............................................... 1 • Changed flyback schematic to represent a more robust design ......................................................................................... 13 • Added flyback supply reliability recommendation................................................................................................................. 18 Changes from Original (March 2013) to Revision A • 2 Page Initial release of full verison. ................................................................................................................................................... 1 Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 ATL431, ATL432 www.ti.com SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 5 Pin Configuration and Functions ATL431 DBZ Package 3-Pin SOT-23 Top View CATHODE ATL432 DBZ Package 3-Pin SOT-23 Top View 1 3 REF ANODE 1 ANODE 3 REF 2 CATHODE 2 Pin Functions PIN NO. NAME I/O DESCRIPTION I/O Shunt Current/Voltage input ATL431x ATL432x CATHODE 1 2 REF 2 1 I Threshold relative to common anode ANODE 3 3 O Common pin, normally connected to ground 6 Specifications 6.1 Absolute Maximum Ratings (1) over operating free-air temperature range (unless otherwise noted) MIN VKA Cathode voltage (2) IKA Continuous cathode current II(ref) Reference input current TJ Tstg (1) (2) MAX UNIT 40 V –100 150 mA –0.05 10 mA Operating virtual junction temperature -40 150 °C Storage temperature –65 150 °C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltage values are with respect to ANODE, unless otherwise noted. 6.2 ESD Ratings VALUE V(ESD) (1) (2) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) ±2000 Charged-device model (CDM), per JEDEC specification JESD22-C101 (2) ±1000 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 6.3 Recommended Operating Conditions VKA Cathode voltage IKA Cathode current TA Operating free-air temperature MIN MAX Vref 36 V mA .035 100 "I" Grade –40 85 "Q" Grade –40 125 Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 UNIT °C 3 ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 www.ti.com 6.4 Thermal Information ATL43xx THERMAL METRIC (1) DBZ (SOT-23) UNIT 3 PINS RθJA Junction-to-ambient thermal resistance 331.8 °C/W RθJC(top) Junction-to-case (top) thermal resistance 106.5 °C/W RθJB Junction-to-board thermal resistance 64.6 °C/W ψJT Junction-to-top characterization parameter 4.9 °C/W ψJB Junction-to-board characterization parameter 62.9 °C/W (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953. 6.5 Electrical Characteristics, ATL431Ax, ATL432Ax over recommended operating conditions, TA = 25°C (unless otherwise noted) PARAMETER Vref Reference voltage TEST CIRCUIT Figure 22 TEST CONDITIONS MIN TYP MAX UNIT 2475 2500 2525 mV ATL43xAI; TA = -40°C to 85°C 5 15 ATL43xAQ; TA = -40°C to 125°C 6 34 ΔVKA = 10 V − Vref –0.4 –2.7 ΔVKA = 36 V − 10 V –0.1 –2 VKA = Vref, IKA = 1 mA Deviation of reference input voltage over full temperature range, see section Figure 22 Ratio of change in reference ΔVref / ΔVKA voltage to the change in cathode voltage Figure 23 IKA = 1 mA Iref Reference input current Figure 23 IKA = 1 mA, R1 = 10 kΩ, R2 = ∞ 30 150 nA II(dev) Deviation of reference input current over full temperature range, see section Figure 23 IKA = 1 mA, R1 = 10 kΩ, R2 = ∞ 20 50 nA Imin Minimum cathode current for regulation Figure 22 Figure 5 VKA = Vref 20 35 µA Ioff Off-state cathode current Figure 24 VKA = 36 V, Vref = 0 0.05 0.2 µA |zKA| Dynamic impedance, see section Figure 22 VKA = Vref, f ≤ 1 kHz, IKA = 1 mA to 100 mA 0.05 0.3 Ω VI(dev) VKA = Vref, IKA = 1 mA, mV mV/V 6.6 Electrical Characteristics, ATL431Bx, ATL432Bx over recommended operating conditions, TA = 25°C (unless otherwise noted) PARAMETER MIN TYP MAX UNIT 2487 2500 2512 mV ATL43xBI; TA = –40°C to 85°C 5 15 ATL43xBQ; TA = –40°C to 125°C 6 34 ΔVKA = 10 V − Vref –0.4 –2.7 ΔVKA = 36 V − 10 V –0.1 –2 IKA = 1 mA, R1 = 10 kΩ, R2 = ∞ 30 150 nA Figure 23 IKA = 1 mA, R1 = 10 kΩ, R2 = ∞ 20 50 nA Minimum cathode current for regulation Figure 22 Figure 5 VKA = Vref 20 35 µA Ioff Off-state cathode current Figure 24 VKA = 36 V, Vref = 0 0.05 0.2 µA |zKA| Dynamic impedance, see section Figure 22 VKA = Vref, f ≤ 1 kHz, IKA = 1 mA to 100 mA 0.05 0.3 Ω Vref Reference voltage VI(dev) TEST CIRCUIT TEST CONDITIONS Figure 22 VKA = Vref, IKA = 1 mA Deviation of reference input voltage over full temperature range, see section Figure 22 VKA = Vref, IKA = 1 mA ΔVref / ΔVKA Ratio of change in reference voltage to the change in cathode voltage Figure 23 IKA = 1 mA Iref Reference input current Figure 23 II(dev) Deviation of reference input current over full temperature range, see section Imin 4 Submit Documentation Feedback mV mV/V Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 ATL431, ATL432 www.ti.com SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 6.7 Typical Characteristics Data at high and low temperatures are applicable only within the recommended operating free-air temperature ranges of the various devices. 0.04 2520 Vref = 2485mV Vref = 2500mV Vref = 2504mV 2515 2510 0.032 IREF (PA) Vref (mV) 2505 2500 2495 0.024 0.016 2490 2485 0.008 2480 2475 -40 -20 0 20 40 60 TA (qC) 80 100 120 0 -40 140 -20 0 20 40 60 TA (qC) 80 100 120 140 IKA=1mA Figure 2. Reference Current vs Free-Air Temperature Figure 1. Reference Voltage vs Free-Air Temperature 100 40 TA = -40qC TA = 25qC TA = 85qC TA = 125qC 80 60 30 40 IKA (PA) IKA (mA) 20 0 -20 20 -40 10 -60 -80 -100 -1.5 0 -1 -0.5 0 0.5 1 1.5 VKA = VREF (V) 2 2.5 3 0 0.5 1 D001 1.5 2 VKA = VREF (V) 2.5 3 D001 Figure 4. Cathode Current vs Cathode Voltage Figure 3. Cathode Current vs Cathode Voltage 0.2 30 0.16 25 IOFF (PA) IKA (PA) Ik(min) 20 15 10 2.3 0.12 0.08 0.04 2.35 2.4 2.45 VKA = VREF (V) 2.5 2.55 Figure 5. Cathode Current vs Cathode Voltage 0 -40 -20 0 20 40 60 TA (qC) 80 100 120 140 Figure 6. Off-State Cathode Current vs Free-Air Temperature Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 5 ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 www.ti.com Typical Characteristics (continued) Data at high and low temperatures are applicable only within the recommended operating free-air temperature ranges of the various devices. -0.1 0 -0.5 -0.15 -1 -0.2 'Vref/'Vka (mV) -1.5 'Vref (mV) -2 -2.5 -3 -3.5 -4 Vref to 10V 10V to 36V -0.25 -0.3 -0.35 -0.4 -4.5 -5 -0.45 -5.5 -0.5 -40 -6 0 5 10 15 20 Vka (V) 25 30 35 40 IKA=1mA -20 0 20 40 60 80 Temperature (qC) 100 140 D001 IKA=1mA Figure 7. Delta Reference Voltage vs Cathode Voltage Figure 8. Delta Reference Voltage vs Cathode Voltage 900 150 Gain Phase 130 840 110 Gain (dB) & Phase (q) Noise (nV/Hz) 120 780 720 660 90 70 50 30 10 -10 -30 600 10 100 1000 Frequency (Hz) -50 1000 10000 10000 100000 1000000 Freq (kHz) D001 Figure 25 used for this measurement. IKA = 1 mA IKA=1mA Figure 10. Small-Signal Voltage Amplification vs Frequency Figure 9. Noise Voltage 0.1 1.2 1.1 0.08 Output Impedance (:) Output Impedance (:) 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.06 0.04 0.02 0.2 0.1 0 100 1000 10000 Frequency (Hz) 100000 1000000 Figure 26 used for this measurement. -20 0 20 40 60 TA (qC) 80 100 120 140 Figure 26 used for this measurement. Figure 11. Output Impedance vs Frequency 6 0 -40 Figure 12. DC Output Impedance vs Temperature Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 ATL431, ATL432 www.ti.com SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 Typical Characteristics (continued) Data at high and low temperatures are applicable only within the recommended operating free-air temperature ranges of the various devices. 2000 1000 Unstable IKA(PA) STABLE 100 STABLE 20 0.0001 0.001 ESR < 20 mΩ IKA = 100 µA 0.01 0.1 CKA(PF) 1 10 D001 Figure 27 used to verify stability. Figure 28 used for this measurement. Figure 13. Pulse Response Figure 14. Low IKA (VKA = 2.5 V) Stability Boundary Conditions all ATL43xx Devices 2000 2000 1000 1000 Unstable Unstable STABLE IKA(PA) IKA(PA) STABLE 100 100 STABLE 20 0.0001 0.001 ESR < 20 mΩ 0.01 0.1 CKA(PF) 1 STABLE 20 0.0001 10 0.001 D001 Figure 27 used to verify stability. ESR < 20 mΩ Figure 15. Low IKA (VKA = 5.0 V) Stability Boundary Conditions all ATL43xx Devices 0.01 0.1 CKA(PF) 1 10 D001 Figure 27 used to verify stability. Figure 16. Low IKA (VKA = 10.0 V) Stability Boundary Conditions all ATL43xx Devices 100 2000 IKA(mA) IKA(PA) 1000 STABLE Unstable 10 100 Stable 20 0.0001 0.001 ESR < 20mΩ 0.01 0.1 CKA(PF) 1 10 1 0.0001 0.001 D001 Figure 27 used to verify stability. Figure 17. Low IKA (VKA = 15.0 V) Stability Boundary Conditions all ATL43xx Devices ESR < 20 mΩ 0.01 0.1 CKA(uF) 1 10 D001 Figure 27 used to verify stability. Figure 18. High IKA (VKA = 2.5 V) Stability Boundary Conditions all ATL43xx Devices Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 7 ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 www.ti.com Typical Characteristics (continued) Data at high and low temperatures are applicable only within the recommended operating free-air temperature ranges of the various devices. 100 100 IKA(mA) IKA(mA) Stable 10 Stable 10 Unstable 1 0.0001 0.001 ESR < 20 mΩ 0.01 0.1 CKA(uF) 1 Unstable 1 0.0001 10 0.001 0.01 0.1 CKA(uF) D001 Figure 27 used to verify stability. ESR < 20 mΩ Figure 19. High IKA (VKA = 5.0 V) Stability Boundary Conditions all ATL43xx Devices 1 10 D001 Figure 27 used to verify stability. Figure 20. High IKA (VKA = 10.0 V) Stability Boundary Conditions all ATL43xx Devices IKA(mA) 100 10 1 0.0001 Stable 0.001 ESR < 20 mΩ 0.01 0.1 CKA(uF) 1 10 D001 Figure 27 used to verify stability. Figure 21. High IKA (VKA = 15.0 V) Stability Boundary Conditions all ATL43xx Devices 8 Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 ATL431, ATL432 www.ti.com SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 7 Parameter Measurement Information The deviation parameters Vref(dev) and Iref(dev) are defined as the differences between the maximum and minimum values obtained over the rated temperature range. The average full-range temperature coefficient of the reference input voltage αVref is defined as: αVref is positive or negative, depending on whether minimum Vref or maximum Vref, respectively, occurs at the lower temperature. |zKA| = ∆VKA ∆I The dynamic impedance is defined as: When the device is operating with two external resistors (see Figure 23), the total dynamic impedance of the KA circuit is given by: |z'| = ∆V ∆I which is approximately equal to VKA Input ( |zKA| 1 + R1 R2 ( Input VKA IKA IKA Vref R1 Iref R2 Vref Figure 23. Test Circuit for VKA > Vref Figure 22. Test Circuit for VKA = Vref Input R1 ö æ VKA = Vref ç 1 + ÷ + Iref × R1 R2 ø è OUTPUT VKA Ioff 10N IK 2.5N 10µF + 5.0V 10N - GND Figure 24. Test Circuit for Ioff Figure 25. Test Circuit for Phase and Gain Measurement Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 9 ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 www.ti.com Parameter Measurement Information (continued) >250 100 OUTPUT IK R1 = 10N + CL IK - R2 Vbat 100 + >250 IK GND + Vbat CL - Figure 26. Test Circuit for Reference Impedance (ZKA) Figure 27. Test Circuit for Stability Boundary Conditions 25N OUTPUT IK Pulse Generator F = 100kHz 50 GND Figure 28. Test Circuit for Pulse Response 10 Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 ATL431, ATL432 www.ti.com SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 8 Detailed Description 8.1 Overview ATL43x is a low power counterpart to TL431 and TLV431, having lower minimum cathode current (Ik(min) = 35 µA vs 0.1/1.0 mA). Like TL431, ATL43x is used in conjunction with it's key components to behave as a single voltage reference, error amplifier, voltage clamp or comparator with integrated reference. ATL43x can be operated and adjusted to cathode voltages from 2.5 V to 36 V, making this part optimum for a wide range of end equipments in industrial, auto, telecom and computing. In order for this device to behave as a shunt regulator or error amplifier, > 35 µA (Imin(max)) must be supplied in to the cathode pin. Under this condition, feedback can be applied from the Cathode and Ref pins to create a replica of the internal reference voltage. Various reference voltage options can be purchased with initial tolerances (at 25°C) of 0.5% and 1.0%. These reference options are denoted by B (0.5%) and A (1.0%) after the ATL43x. The ATL43xxI devices are characterized for operation from –40°C to 85°C, and the ATL43xxQ devices are characterized for operation from –40°C to 125°C. 8.2 Functional Block Diagram CATHODE REF + Vref ANODE 8.3 Feature Description ATL43x consists of an internal reference and amplifier that outputs a sink current based on the difference between the reference pin and the virtual internal pin. The sink current is produced by an internal Darlington pair. When operated with enough voltage headroom (≥ 2.5 V) and cathode current (IKA), ATL43x forces the reference pin to 2.5 V. However, the reference pin can not be left floating, as it needs Iref ≥ 0.1 µA (please see the Functional Block Diagram). This is because the reference pin is driven into an NPN, which needs base current in order operate properly. When feedback is applied from the Cathode and Reference pins, ATL43x behaves as a Zener diode, regulating to a constant voltage dependent on current being supplied into the cathode. This is due to the internal amplifier and reference entering the proper operating regions. The same amount of current needed in the above feedback situation must be applied to this device in open loop, servo or error amplifying implementations in order for it to be in the proper linear region giving ATL43x enough gain. Unlike many linear regulators, ATL43x is internally compensated to be stable without an output capacitor between the cathode and anode; however, if it is desired to use an output capacitor Figure 14 through Figure 21 can be used as a guide to assist in choosing the correct capacitor to maintain stability. Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 11 ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 www.ti.com 8.4 Device Functional Modes 8.4.1 Open Loop (Comparator) When the cathode/output voltage or current of ATL43x is not being fed back to the reference/input pin in any form, this device is operating in open loop. With such high gain in this configuration, ATL43x is typically used as a comparator. Due to the integrated reference, the ATL43x allows users to monitor a certain level of a single signal. 8.4.2 Closed Loop When the cathode/output voltage or current of ATL43x is being fed back to the reference/input pin in any form, this device is operating in closed loop. The majority of applications involving ATL43x use it in this manner to regulate a fixed voltage or current. The feedback enables this device to behave as an error amplifier, computing a portion of the output voltage and adjusting it to maintain the desired regulation. This is done by relating the output voltage back to the reference pin in a manner to make it equal to the internal reference voltage, which can be accomplished via resistive or direct feedback. 12 Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 ATL431, ATL432 www.ti.com SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 9 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 9.1 Application Information Figure 29 shows the ATL43x used in a 24-V isolated flyback supply. The output of the regulator, plus the forward voltage drop of the optocoupler LED (2.5 + 0.7 = 3.2 V), determine the minimum voltage that can be regulated in an isolated supply configuration. Regulated voltage as low as 5.0 Vdc is possible in the topology shown in Figure 29. The 431 family of devices are prevalent in these applications, being designers go to choice for secondary side regulation. Due to this prevalence, this section will further go on to explain operation and design in both states of ATL43x that this application will see, open loop (Comparator + Vref) and closed loop (Shunt Regulator). ATL43x's key benefit in isolated supplies is the no load power savings gained by the > 20x decrease in IKmin from TL431. More information about this and other benefits can be found in the application note Designing with the "Advanced" TL431, ATL431 SLVA685. Further information about system stability and using a ATL43x device for compensation can be found in the application note Compensation Design With TL431 for UCC28600, SLUA671. VI 120 V Vo=24 V Gate Drive VCC Ibias Controller VFB Current Sense GND ATL431 Figure 29. Flyback With Isolation Using ATL43x as Voltage Reference and Error Amplifier Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 13 ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 www.ti.com 9.2 Typical Applications 9.2.1 Comparator With Integrated Reference (Open Loop) Vsup Rsup Vout CATHODE R1 VL RIN REF VIN + R2 2.5V ANODE Figure 30. Comparator Application Schematic 9.2.1.1 Design Requirements For this design example, use the parameters listed in Table 1 as the input parameters. Table 1. Design Parameters DESIGN PARAMETER EXAMPLE VALUE Input voltage range 0 V to 3.3 V Input resistance 100 kΩ Supply voltage 5V Cathode current (IK) 50 µA Output voltage level About 2 V to Vsup Logic input thresholds VIH/VIL 1.5 V / 0.8 V 9.2.1.2 Detailed Design Procedure When using ATL43x as a comparator with reference, determine the following: • Input voltage range • Reference voltage accuracy • Output logic input high and low level thresholds • Current source resistance 9.2.1.2.1 Basic Operation In the configuration shown in Figure 30 ATL43x will behave as a comparator, comparing the Vref pin voltage to the internal virtual reference voltage. When provided a proper cathode current (Ik), ATL43x will have enough open loop gain to provide a quick response. With the ATL43x's max operating current (Imin) being 35 µA and up to 40 µA over temperature, operation below that could result in low gain, leading to a slow response. 14 Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 ATL431, ATL432 www.ti.com SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 9.2.1.2.2 Overdrive Slow or inaccurate responses can also occur when the reference pin is not provided enough overdrive voltage. This is the amount of voltage that is higher than the internal virtual reference. The internal virtual reference voltage will be within the range of 2.5 V ±(0.5% or 1.0%) depending on which version is being used. The more overdrive voltage provided, the faster the ATL43x will respond. For applications where ATL43x is being used as a comparator, it is best to set the trip point to greater than the positive expected error (that is, +1.0% for the A version). For fast response, setting the trip point to > 10% of the internal Vref should suffice. Figure 31 shows the transition from VOH to VOL based on the input voltage and can be used as a guide for selecting the overdrive voltage. For minimal voltage drop or difference from Vin to the ref pin, it is recommended to use an input resistor < 1 MΩ to provide Iref. 9.2.1.2.3 Output Voltage and Logic Input Level In order for ATL43x to properly be used as a comparator, the logic output must be readable by the receiving logic device. This is accomplished by knowing the input high and low level threshold voltage levels, typically denoted by VIH and VIL. As seen in Figure 31, ATL43x's output low level voltage in open-loop/comparator mode is ~2 V, which is sufficient for some ≥ 5.0 V supplied logic. However, would not work for 3.3 V and 1.8 V supplied logic. In order to accommodate this, a resistive divider can be tied to the output to attenuate the output voltage to a voltage legible to the receiving low voltage logic device. ATL43x's output high voltage is approximately Vsup due to ATL43x being open-collector. If Vsup is much higher than the receiving logic's maximum input voltage tolerance, the output must be attenuated to accommodate the outgoing logic's reliability. When using a resistive divider on the output, be sure to make the sum of the resistive divider (R1 and R2 in Figure 30) is much greater than Rsup in order to not interfere with ATL43x's ability to pull close to Vsup when turning off. 9.2.1.2.3.1 Input Resistance ATL43x requires an input resistance in this application in order to source the reference current (Iref) needed from this device to be in the proper operating regions while turning on. The actual voltage seen at the ref pin will be: Vref = Vin – Iref × Rin (1) Because Iref can be as high as 0.15 µA, TI recommends to use a resistance small enough that will mitigate the error that Iref creates from Vin. Also, the input resistance must be set high enough as to not surpass the absolute maximum of 10 mA. VOUT (V) 9.2.1.3 Application Curve 5.5 5.25 5 4.75 4.5 4.25 4 3.75 3.5 3.25 3 2.75 2.5 2.25 2 1.75 1.5 2 2.1 2.2 2.3 2.4 2.5 2.6 VIN (V) 2.7 2.8 2.9 3 D001 RIN = 100 kΩ VSUP = 5.0 V RSUP = 10 kΩ Figure 31. Open Loop (Comparator Mode) VOUT vs VIN Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 15 ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 www.ti.com 9.2.2 Shunt Regulator/Reference RSUP VSUP VO = ( 1 + R1 0.1% R2 ) VREF CATHODE REF VREF R1 R2 0.1% ATL431 CL ANODE Figure 32. Shunt Regulator Schematic 9.2.2.1 Design Requirements For this design example, use the parameters listed in Table 2 as the input parameters. Table 2. Design Parameters DESIGN PARAMETER EXAMPLE VALUE Reference initial accuracy 1.0% Supply voltage 48 V Cathode current (IK) 50 µA Output voltage level 2.5 V to 36 V Load capacitance 1 nF Feedback resistor values and accuracy (R1 and R2) 10 kΩ 9.2.2.2 Detailed Design Procedure When using ATL43x as a Shunt Regulator, determine the following: • Input voltage range • Temperature range • Total accuracy • Cathode current • Reference initial accuracy • Output capacitance 9.2.2.2.1 Programming Output/Cathode Voltage In order to program the cathode voltage to a regulated voltage a resistive bridge must be shunted between the cathode and anode pins with the mid point tied to the reference pin. This can be seen in Figure 32, with R1 and R2 being the resistive bridge. The cathode/output voltage in the shunt regulator configuration can be approximated by the equation shown in Figure 32. The cathode voltage can be more accurately determined by taking in to account the cathode current: VO = (1 + R1 / R2) × Vref – Iref × R1 (2) For this equation to be valid, ATL43x must be fully biased so that it has enough open loop gain to mitigate any gain error. This can be done by meeting the Imin spec denoted in Electrical Characteristics, ATL431Ax, ATL432Ax table. 9.2.2.2.2 Total Accuracy When programming the output above unity gain (VKA = Vref), ATL43x is susceptible to other errors that may effect the overall accuracy beyond Vref. These errors include: • • 16 R1 and R2 accuracies VI(dev) - Change in reference voltage over temperature Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 ATL431, ATL432 www.ti.com • • SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 ΔVref / ΔVKA - Change in reference voltage to the change in cathode voltage |zKA| - Dynamic impedance, causing a change in cathode voltage with cathode current Worst case cathode voltage can be determined taking all of the variables in to account. Application note SLVA445 assists designers in setting the shunt voltage to achieve optimum accuracy for this device. 9.2.2.2.3 Stability Though ATL43x is stable with no capacitive load, the device that receives the shunt regulator's output voltage could present a capacitive load that is within the ATL43x region of stability, shown in Figure 14 through Figure 21. Also, designers may use capacitive loads to improve the transient response or for power supply decoupling. Figure 14 through Figure 21 should be used as a guide for capacitor selection and compensation. It is characterized using ceramic capacitors with very-low ESR. When it is desirable to use a capacitor within the unstable region, higher ESR capacitors can be used to stabilize ATL43x or an external series resistance can be added. For more information and guidance on ESR values, please refer to the application note Designing with the "Advanced" TL431, ATL431 SLVA685. Unlike TL431, the stability boundary is characterized and determined with resistors 250 Ω and greater. Which is more suitable for low cathode current applications. 9.2.2.3 Application Curves Figure 33. ATL43x Start-up Response IKA = 50 µA Figure 34. ATL43x Start-up Response IKA = 1 mA Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 17 ATL431, ATL432 SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 www.ti.com 10 Power Supply Recommendations When using ATL43x in a flyback supply (see Figure 29) it is often common for designers to place the bias resistor between the Anode of the Opto-Coupler and the output voltage (VO = 24 V). However, this makes ATL43x more susceptible to EOS/ESD damage. Therefore, it is recommended to place the bias resistor between the Cathodes of the Opto-Coupler and ATL43x, as shown in Figure 29. For further explanation, please see Designing with the "Advanced" TL431, ATL431 SLVA685. When using ATL43x as a Linear Regulator to supply a load, designers will typically use a bypass capacitor on the output/cathode pin. Be sure that the capacitance is within the stability criteria shown in Figure 14 through Figure 21. In order to not exceed the maximum cathode current, be sure that the supply voltage is current limited. Also, be sure to limit the current being driven into the Ref pin, as not to exceed it's absolute maximum rating. For applications shunting high currents, pay attention to the cathode and anode trace lengths, adjusting the width of the traces to have the proper current density. 11 Layout 11.1 Layout Guidelines Place decoupling capacitors as close to the device as possible. Use appropriate widths for traces when shunting high currents to avoid excessive voltage drops. 11.2 Layout Example DBZ (TOP VIEW) Rref Vin REF 1 Rsup Vsup ANODE 3 CATHODE 2 GND CL GND Figure 35. DBZ Layout Example 18 Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 ATL431, ATL432 www.ti.com SLVSCV5C – MARCH 2015 – REVISED SEPTEMBER 2015 12 Device and Documentation Support 12.1 Related Links The table below lists quick access links. Categories include technical documents, support and community resources, tools and software, and quick access to sample or buy. Table 3. Related Links PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL DOCUMENTS TOOLS & SOFTWARE SUPPORT & COMMUNITY ATL431 Click here Click here Click here Click here Click here ATL432 Click here Click here Click here Click here Click here 12.2 Community Resources The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use. TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers. Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support. 12.3 Trademarks E2E is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. 12.4 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 12.5 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 13 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. Submit Documentation Feedback Copyright © 2015, Texas Instruments Incorporated Product Folder Links: ATL431 ATL432 19 PACKAGE OPTION ADDENDUM www.ti.com 12-Oct-2015 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) ATL431AIDBZR ACTIVE SOT-23 DBZ 3 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM -40 to 85 (ZCKS ~ ZCR3) ATL431AQDBZR ACTIVE SOT-23 DBZ 3 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM -40 to 125 (ZCLS ~ ZCS3) ATL431BIDBZR ACTIVE SOT-23 DBZ 3 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM -40 to 85 (ZCMS ~ ZCT3) ATL431BQDBZR ACTIVE SOT-23 DBZ 3 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM -40 to 125 (ZCJS ~ ZCU3) ATL432AIDBZR ACTIVE SOT-23 DBZ 3 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM -40 to 85 (ZCNS ~ ZCV3) ATL432AQDBZR ACTIVE SOT-23 DBZ 3 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM -40 to 125 (ZCOS ~ ZCW3) ATL432BIDBZR ACTIVE SOT-23 DBZ 3 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM -40 to 85 (ZCPS ~ ZCX3) ATL432BQDBZR ACTIVE SOT-23 DBZ 3 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM -40 to 125 (ZCQS ~ ZCY3) (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. 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. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com (4) 12-Oct-2015 There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. 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Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 24-Feb-2016 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) ATL431AIDBZR SOT-23 DBZ 3 3000 180.0 8.4 ATL431AQDBZR SOT-23 DBZ 3 3000 180.0 ATL431BIDBZR SOT-23 DBZ 3 3000 180.0 ATL431BQDBZR SOT-23 DBZ 3 3000 ATL432AIDBZR SOT-23 DBZ 3 ATL432AQDBZR SOT-23 DBZ ATL432BIDBZR SOT-23 DBZ ATL432BQDBZR SOT-23 DBZ 3.15 2.77 1.22 4.0 8.0 Q3 8.4 3.15 2.77 1.22 4.0 8.0 Q3 8.4 3.15 2.77 1.22 4.0 8.0 Q3 180.0 8.4 3.15 2.77 1.22 4.0 8.0 Q3 3000 180.0 8.4 3.15 2.77 1.22 4.0 8.0 Q3 3 3000 180.0 8.4 3.15 2.77 1.22 4.0 8.0 Q3 3 3000 180.0 8.4 3.15 2.77 1.22 4.0 8.0 Q3 3 3000 180.0 8.4 3.15 2.77 1.22 4.0 8.0 Q3 Pack Materials-Page 1 W Pin1 (mm) Quadrant PACKAGE MATERIALS INFORMATION www.ti.com 24-Feb-2016 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ATL431AIDBZR SOT-23 DBZ 3 3000 202.0 201.0 28.0 ATL431AQDBZR SOT-23 DBZ 3 3000 202.0 201.0 28.0 ATL431BIDBZR SOT-23 DBZ 3 3000 202.0 201.0 28.0 ATL431BQDBZR SOT-23 DBZ 3 3000 202.0 201.0 28.0 ATL432AIDBZR SOT-23 DBZ 3 3000 202.0 201.0 28.0 ATL432AQDBZR SOT-23 DBZ 3 3000 202.0 201.0 28.0 ATL432BIDBZR SOT-23 DBZ 3 3000 202.0 201.0 28.0 ATL432BQDBZR SOT-23 DBZ 3 3000 202.0 201.0 28.0 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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