SPX2431. Precision Adjustable Shunt Regulator. Description. Functional Block Diagram. Cathode (K) Reference (R) 2.5V. Anode (A)

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1 Precision Adjustable Shunt Regulator Description The is a 3-terminal adjustable shunt voltage regulator providing a highly accurate bandgap reference. The acts as an open-loop error amplifier with a 2.5V temperature compensation reference. The s thermal stability, wide operating current (1mA) and temperature range ( C to 15 C) makes it suitable for a variety of applications that require a low cost, high performance solution. A tolerance of.5% is proven to be sufficient to overcome all of the other errors in the system to virtually eliminate the need for trimming in the power supply manufacturer s assembly lines and contribute a significant cost savings. The output voltage may be adjusted to any value between V REF and 2 volts with two external resistors. In the standard shunt configuration, the combination of a low temperature coefficient, sharp turn on characteristics, low output impedance, and programmable output voltage makes this precision reference an excellent error amplifier. The is available in a SOT-23-3 package. FEATURES Trimmed bandgap to.5% and 1.% Wide operating current 1mA to 1mA Extended temperature range: C to 15 C Low temperature coefficient: 3 ppm/ C Offered in 3 Pin SOT-23 (M) Replacement for TL431, AS2431 Low noise output APPLICATIONS Battery operating equipment Adjustable supplies Switching power supplies Error amplifiers Single supply amplifier Monitors / VCRs / TVs Personal computers Ordering Information - Back Page Functional Block Diagram Cathode (K) Reference (R) + 2.5V - Anode (A) 1/9

2 Absolute Maximum Ratings NOTE: Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. Cathode-Anode Reverse Breakdown V KA... 2V Anode-Cathode Forward Current, (< 1ms) I AK... 1A Operating Cathode Current A... 1mA Reference Input Current I REF... 1.mA Recommended Conditions Cathode Voltage V KA...V REF to 2V Cathode Current... 1mA Typical Thermal Resistances SOT-23 Ѳ JA C/W Ѳ JC C/W Typical Derating mW/ C Typical deratings of the thermal resistances are given for ambient temperature >25 C. Continuous Power Dissipation at 25 C P D SOT mW Junction Temperature T J...15 C Storage Temperature T STG C to 15 C Electrical Characteristics Electrical characteristics at 25 C, = 1mA, V K = V REF, unless otherwise specified. PARAMETERS SYMBOL FIGURE CONDITIONS MIN. TYP. MAX. MIN. TYP. MAX. UNITS A Reference voltage V REF 2 T J = C to 15 C V REF with temp. TC mv/ C Ratio of change in V REF to cathode voltage V REF V REF to 1V V K 3 1V to 2V Reference input current I REF μa I REF temp deviation I REF 3 T J = C to 15 C μa Min for regulation (MIN) ma Off state leakage (OFF) 4 Dynamic output impedance Z KA 2 V REF = V, V KA = 2V f Z 1kHz = 1 to 1mA V mv/v na Ω Pin Configuration SOT-23-3 (M) ANODE REF CATHODE Top View 2/9

3 Calculating Average Temperature Coefficient (TC) ppm % mv V REF TC in mv / C = V REF (mv) T A T TC in % / C = V REF x 1 ( V REF at 25 C) T A Junction Temperature ( C) TC in ppm / C = V REF x 1 ( V REF at 25 C) 6 T A.33mV / C.27% / C 27ppm/ C Figure 1: V REF vs. Temperature Test Circuits V KA V KA (OFF) I REF I REF (V REF ) Figure 2: Test Circuit for Figure 3: Test Circuit for V KA > V REF Figure 4: Test Circuit for OFF 3/9

4 Typical Performance Characteristics IK Cathode Current (ma) C to 15 C V KA Cathode Voltage (V) Figure 5: High Current Operating Characteristics VREF Reference Voltage (V) = 1mA T A Ambient Temperature ( C) Figure 6: Reference Voltage vs. Ambient Temperature IK Cathode Current (µa) to 15 C C 25 C - C V KA Cathode Voltage (V) Figure 7: Low Current Operating Characteristics IREF Reference Input Current (µa) = 1kΩ = = 1mA T A Ambient Temperature ( C) Figure 8: Reference Input Current vs. Ambient Temperature 7 VREF (mv) A = 1mA C 25 C 75 C V KA Cathode Voltage (V) 125 C Figure 9: Reference Voltage Line Regulation vs. Cathode Voltage and T AMBIENT Noise Voltage nv/ Hz = 1mA T A = 25 C 1 1 1K 1K 1K f Frequency (Hz) Figure 1: Noise Voltage vs. Frequency 4/9

5 Typical Performance Characteristics (continued) ZKA Dynamic Impedance (Ω) = 1 to 1mA f 1kHz 6dB 5dB 4dB 3dB 2dB 1dB db -1dB -2dB REF LEVEL 6.dB.deg /DIV 1.dB 45.deg MARKER Hz MAG (A/R) -.25 db MARKER Hz PHASE (A/R) deg GAIN PHASE T A Free Air Temperature Figure 11: Low Frequency Dynamic Output Impedance vs. T AMBIENT -3dB -4dB 1 1 1K 1K 1K 1M 1M START 1.Hz STOP 5.Hz Figure 12. Small Signal Gain and Phase vs. Frequency; = 1mA, T A = 25 C µF 15kΩ 23Ω 8.25kΩ GND Figure 13. Test Circuit for Gain and Phase Frequency Response Figure 14. Frequency = 1kHz, = 1mA, T A = 25 C f p = 1kHz 25Ω 5Ω GND Figure 15. Test Circuit for Pulse Response IK Cathode Current (ma) A: B: V KA = 5V at =1mA C: V KA =1V at =1mA D: V KA =15V at =1mA T A = 25 C STABLE C L Load Capacitance (pf) Figure 16. Stability Boundry Conditions B A C D STABLE 5/9

6 Typical Performance Characteristics (continued) 1 15Ω R 1kΩ C L ZKA Dynamic Impedance (Ω) T A = 25 C = 1 to 1mA Figure 17: Test Circuit for Stability.1 1K 1K 1K 1M 1M f Frequency (Hz) Figure 18: Dynamic Output Impedance T A = 25 C, = 1 to 1mA 1 R3 IKOFF Cathode Current (na) V KA = 2V V REF = V T A Ambient Temperature ( C) Figure 19: Off State Leakage.1% V REF.1% Figure 2: Shunt Regulator = (1+/)V REF I SINK Q1 Opto Isolator R3.1% Isolated Feedback R3 sets feedback gain, C1 provides feedback compensation.1% C2 + C1 RTN.1% Figure 21: Constant Current, Sink, I SINK = V REF / Figure 22: Reference Amplifier for Isolated Feedback in Off-Line DC-DC Converters 6/9

7 Typical Performance Characteristics (continued) R5 R4.1% R3 C1.1%.1% R3.1% Q1 Figure 23: Precision High Current Series Regulator = (1+/)V REF Figure 24: High Current Shunt Regulator = (1+/)V REF V CC * Resistor values are chosen such that the effect to I REF is negligible. Figure 25: Single Supply Comparator with Temperature Compensated Threshold. Threshold = 2.5V 7/9

8 Mechanical Dimensions SOT /9

9 Ordering Information (1) Part Number Operating Temperature Range Lead-Free Package Packaging Method Accuracy AM-L/TR.5% C to 15 C Yes (2) 3-pin SOT-23 Tape and Reel M-L/TR 1.% Output Voltage 2.5V NOTE: 1. Refer to for most up-to-date Ordering Information. 2. Visit for additional information on Environmental Rating. Revision History Revision Date Description 1A 11/17/217 Added MaxLinear logo. Updated format and ordering information table from previous revision dated 1/19/5. Pinout moved to page 2. Corrected typo for E min in mechanical dimensions. Corporate Headquarters: 5966 La Place Court Suite 1 Carlsbad, CA 928 Tel.:+1 (76) Fax: +1 (76) High Performance Analog: 16 Rincon Circle San Jose, CA Tel.: +1 (669) Fax: +1 (669) powertechsupport@exar.com The content of this document is furnished for informational use only, is subject to change without notice, and should not be construed as a commitment by MaxLinear, Inc.. MaxLinear, Inc. assumes no responsibility or liability for any errors or inaccuracies that may appear in the informational content contained in this guide. Complying with all applicable copyright laws is the responsibility of the user. Without limiting the rights under copyright, no part of this document may be reproduced into, stored in, or introduced into a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise), or for any purpose, without the express written permission of MaxLinear, Inc. Maxlinear, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless MaxLinear, Inc. receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of MaxLinear, Inc. is adequately protected under the circumstances. MaxLinear, Inc. may have patents, patent applications, trademarks, copyrights, or other intellectual property rights covering subject matter in this document. Except as expressly provided in any written license agreement from MaxLinear, Inc., the furnishing of this document does not give you any license to these patents, trademarks, copyrights, or other intellectual property. Company and product names may be registered trademarks or trademarks of the respective owners with which they are associated. 217 MaxLinear, Inc. All rights reserved _DS_ /9

June 2012 Rev FEATURES. Fig. 1: SPX431L Precision Adjustable Shunt Regulator

June 2012 Rev FEATURES. Fig. 1: SPX431L Precision Adjustable Shunt Regulator June 2012 Rev. 2.0.0 GENERAL DESCRIPTION The SPX431L is a 3-terminal adjustable shunt voltage regulator providing a highly accurate bandgap reference. The SPX431L acts as an open-loop error amplifier with