LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES T H E I N F I N I T E P O W E R I O F P N N O VA T I O N R O D U C T I O N DESCRIPTION The LX6431 series precision adjustable three terminal shunt voltage regulators are pin-to-pin compatible with the industry standard TL431, but with significant improvements. The LX6431 design has eliminated regions of instability common to older generation shunt regulator products like the TL431. Designs are made simpler by eliminating the task of insuring capacitive loads, and output voltage and cathode currents don't combine for unstable operation. The capacitor value is chosen simply to give the best load transient response without the possibility of instability. A lower reference input current allows the use of higher value reference divider resistors, D A T A S H E E T K E Y F E AT U R E S ■ Unconditionally Stable For All Cathode To Anode Capacitance Values ■ Reduced Reference Input Current Allowing The Use Of Higher Value Divider Resistors (0.5µA Max.) ■ Initial Voltage Reference Accuracy Of 0.4% (LX6431B) ■ Sink Current Capability 0.6mA to 100mA ■ Typical Output Dynamic Impedance Less Than 100mΩ ■ Adjustable Output Voltage From 2.5V to 36V reducing the current drain from batteries in portable equipment as well as reducing the voltage programming errors due to the impedance of the divider network (See Product Highlight figure below). In addition, the LX6431B has an improved initial accuracy of 0.4%, and the output voltage is programmable by using two external resistors from 2.5V to 36V. These devices offer low output impedance for improved load regulation. The typical output impedance of these devices is 100mΩ. The reduced reference input bias current and minimum operating currents make these devices suitable for portable and micropower applications. NOTE: For current data & package dimensions, visit our web site: http://www.linfinity.com. PRODUCT HIGHLIGHT O U T P U T V O L TA G E E R R O R DUE TO I REF T Y P I C A L P R O G R A M M A B L E V O LTA G E REFERENCE CIRCUIT 20 18 VIN 16 VKA % Error 14 R1 12 10 LX6431 8 R2 6 4 2 GND 0 2.5 3.75 5 6.25 7.5 8.75 10 11.25 (VKA) Output Voltage - (V) 12.5 13.75 15 PA C K A G E O R D E R I N F O R M A T I O N TA (°C) 0 to 70 -40 to 85 Initial Tolerance 2% 1% 0.4% 2% 1% 0.4% SOIC DM Plastic 8-pin LX6431CDM LX6431ACDM LX6431BCDM LX6431IDM LX6431AIDM LX6431BIDM TO-92 LP Plastic 3-pin LX6431CLP LX6431ACLP LX6431BCLP LX6431ILP LX6431AILP LX6431BILP Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (i.e. LX5212CDPT) TO-92 (LP) package also available in ammo-pack. Copyright © 1999 Rev. 1.4 6/99 LINFINITY MICROELECTRONICS INC. 11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: 714-893-2570 1 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P R O D U C T I O N ABSOLUTE MAXIMUM RATINGS D A T A S H E E T PACKAGE PIN OUTS (Note 1) Cathode to Anode Voltage (VKA) ................................................................... -0.3V to 37V Reference Input Current (IREF) .................................................................... -50µA to 10µA Continuous Cathode Current (IK) ......................................................... -100mA to 150mA Operating Junction Temperature Plastic (DM & LP Packages) ................................................................................. 150°C Storage Temperature Range ...................................................................... -65°C to 150°C Lead Temperature ..................................................................................................... 300°C Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. Pin numbers refer to DIL packages only. CATHODE N.C. ANODE N.C. 1 8 2 7 3 6 4 5 REF ANODE ANODE N.C. DM PACKAGE (Top View) 1. CATHODE 2. ANODE THERMAL DATA 3. REF DM PACKAGE: THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA 165°C/W LP PACKAGE: THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA LP PACKAGE (Top View) 156°C/W Junction Temperature Calculation: TJ = TA + (PD x θJA). The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow BLOCK D IA GR A M Cathode (K) Ref (R) VREF Anode (A) 2 Copyright © 1999 Rev. 1.4 6/99 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P R O D U C T I O N D A T A S H E E T ELECTRICAL CHARACTERISTICS (Note 2) (Unless otherwise specified, these specifications apply over the operating ambient temperatures for LX6431C/LX6431AC/LX6431BC with 0°C ≤ TA ≤ 70°C, LX6431I/LX6431AI/LX6431BI with -40°C ≤ TA ≤ 85°C.) Parameter Reference Input Voltage Reference Drift Symbol LX6431 LX6431A LX6431B LX6431 VREF LX6431A LX6431B Voltage Ratio, Reference to Cathode (Note 3) Reference Input Current IREF Minimum Operating Current IMIN Off-State Cathode Current Dynamic Impedance IOFF ZKA Test Conditions IK = 10mA, VKA = VREF, TA = 25°C, IK = 10mA, VKA = VREF, TA = 25°C IK = 10mA, VKA = VREF, TA = 25°C IK = 10mA, VKA = VREF, 0°C ≤ TA ≤ 70°C IK = 10mA, VKA = VREF, -40°C ≤ TA ≤ 85°C IK = 10mA, VKA = VREF, 0°C ≤ TA ≤ 70°C IK = 10mA, VKA = VREF, -40°C ≤ TA ≤ 85°C IK = 10mA, VKA = VREF, 0°C ≤ TA ≤ 70°C IK = 10mA, VKA = VREF, -40°C ≤ TA ≤ 85°C IK = 10mA, VKA = 2.5V to 36V, TA = 25°C IK = 10mA, VKA = 2.5V to 36V, TA = Operating Range VKA = VREF, TA = 25°C VKA = VREF, TA = Operating Range VKA = VREF to 36V, TA = 25°C VKA = VREF to 36V, TA = Operating Range VKA = 36V, VREF = 0V, TA = 25°C VKA = VREF, IK = 0.6mA to 100mA, f ≤ 1kHz, TA = 25°C LX6431 Units Min. Typ. Max. 2440 2470 2490 0.3 0.3 0.1 0.1 0.4 0.4 0.3 30 2550 2520 2510 15 25 15 25 15 20 1 1 0.5 0.5 0.6 0.6 1 100 mV mV mV mV mV mV mV mV mV mV/V mV/V µA µA mA mA µA mΩ Note 2. These parameters are guaranteed by design. Note 3. ∆VREF ∆VKA Copyright © 1999 Rev. 1.4 6/99 Ratio of change in reference input voltage to the change in cathode voltage. 3 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P R O D U C T I O N D A T A S H E E T GRAPH / CURVE INDEX FIGURE INDEX Characteristic Curves Application Information FIGURE # FIGURE # 1. REFERENCE VOLTAGE vs. FREE-AIR TEMPERATURE 7. 2. REFERENCE CURRENT vs. FREE-AIR TEMPERATURE COMPARISON OF REFERENCE RESISTOR VALUES BETWEEN AN LX6431B AND A TL1431. Resistors used with the LX6431B are 5 times higher in value. 3. CATHODE CURRENT vs. CATHODE VOLTAGE 8. 4. OFF-STATE CATHODE CURRENT vs. FREE-AIR TEMPERATURE 5. RATIO OF DELTA REFERENCE VOLTAGE TO DELTA CATHODE VOLTAGE vs. FREE-AIR TEMPERATURE COMPARISON OF REFERENCE RESISTOR VALUES BETWEEN AN LX6431B AND A TL1431. When used as 0.5%, 5V shunt regulators. 6. EQUIVALENT INPUT NOISE VOLTAGE vs. FREQUENCY Parameter Measurement Information FIGURE # 9. TEST CIRCUIT FOR VKA = VREF 10. TEST CIRCUIT FOR VKA > VREF 11. TEST CIRCUIT FOR IOFF Typical Characteristics FIGURE # 12. EQUIVALENT INPUT NOISE VOLTAGE OVER A 10-SECOND PERIOD 13. SMALL-SIGNAL VOLTAGE AMPLIFICATION vs. FREQUENCY 14. REFERENCE IMPEDANCE vs. FREQUENCY 15. PULSE RESPONSE 16. DIFFERENTIAL VOLTAGE AMPLIFICATION vs. FREQUENCY 4 Copyright © 1999 Rev. 1.4 6/99 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P R O D U C T I O N D A T A S H E E T CHARACTERISTIC CURVES FIGURE 1. — REFERENCE VOLTAGE vs. FREE-AIR TEMPERATURE FIGURE 2. — REFERENCE CURRENT vs. FREE-AIR TEMPERATURE 0.15 IK = 10mA R1 = 10k VREF = VKA IK = 10mA (IREF) Reference Current - (µA) (VREF) Reference Voltage - (V) 2.52 2.51 2.50 2.49 2.48 -50 -25 25 0 50 75 100 0.14 0.13 0.12 0.11 0.1 -50 125 (TA) Ambient Temperature - (°C) 25 50 75 100 125 FIGURE 4. — OFF-STATE CATHODE CURRENT vs. FREE-AIR TEMPERATURE 800 0.8 (IOFF) Off-State Cathode Current - (µA) VKA = VREF TA = 25°C (IK) Cathode Current - (µA) 0 (TA) Ambient Temperature - (°C) FIGURE 3. — CATHODE CURRENT vs. CATHODE VOLTAGE 600 400 200 0 -200 -2 -1 0 1 2 (VKA) Cathode Voltage - (V) Copyright © 1999 Rev. 1.4 6/99 -25 3 4 0.7 VKA = 36V VREF = 0 0.6 0.5 0.4 0.3 0.2 0.1 0 -50 -25 0 25 50 75 100 125 (TA) Ambient Temperature - (°C) 5 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P R O D U C T I O N D A T A S H E E T CHARACTERISTIC CURVES FIGURE 5. — RATIO OF DELTA REFERENCE VOLTAGE TO DELTA CATHODE VOLTAGE vs. FREE-AIR TEMPERATURE FIGURE 6. — EQUIVALENT INPUT NOISE VOLTAGE vs. FREQUENCY 0 260 VKA = 3V to 36V (VN) Noise Voltage - (nV/ Hz) ∆VREF / ∆VKA - (mV/V) IO = 10mA TA = 25°C 240 -0.1 -0.2 -0.3 -0.4 -0.5 220 200 180 160 140 120 -0.6 -50 -25 0 25 50 75 100 (TA) Ambient Temperature - (°C) 6 125 100 10 100 1k 10k 100k (f) Frequency - (Hz) Copyright © 1999 Rev. 1.4 6/99 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P R O D U C T I O N D S A T A H E E T A P P L I C AT I O N I N F O R M AT I O N Application Hints The reference input current of the LX6431 series voltage references is much lower than other similar precision parts. This helps to design programmable voltage references that can use much higher value programming resistors while maintaining the same accuracy as the other precision parts. Figure 7 below shows a 5V, 1% shunt regulator using the LX6431B and a shunt regulator using the TL1431 (Also available from Linfinity). Figure 8 shows 0.5% shunt regulators. Noteworthy are the values of the reference resistors used in the two circuits. With the LX6431B it is possible to use 25k resistors for setting the output voltage with 1% precision as opposed to 5k programming resistors when the same precision needs to be achieved with a TL1431. VKA 5V, 0.5% VIN R1 25k 0.1% R2 1k 0.1% GND a) VKA 5V, 0.5% VIN R1 240 0.1% R2 240 0.1% TL1431 LX6431B R2 1k 0.1% LX6431B VKA 5V, 1% VIN R1 25k 0.1% GND b) GND a) VKA 5V, 1% VIN R1 5k 0.1% R2 5k 0.1% TL1431 GND b) FIGURE 7 — Comparison of reference resistor values between an LX6431B and an TL1431, resistors used with the LX6431B are 5 times higher in value. Copyright © 1999 Rev. 1.4 6/99 FIGURE 8 — Comparison of reference resistor values between an LX6431B and a TL1431, when used as 0.5%, 5V shunt regulators. The output voltage of the reference can be programmed by using the formula below: R1 VKA ≅ 2.5 ∗ 1 + R2 If more accuracy is required then the effects of the input bias current (IREF) must be taken into account. The formula below accounts for the error this current produces. R1 VKA = 2.5 ∗ 1 + + IREF ∗ R1 R2 Smaller values of programming resistors tend to minimize bias current errors. In this respect the low input current characteristics of the LX6431B helps to reduce the power dissipation on the programming resistors by a factor of five compared to other references like the TL1431 and TL431. The LX6431 series of voltage references have an enhanced circuit design that can tolerate any value of cathode to anode capacitance. 7 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P R O D U C T I O N D A T A S H E E T PA R A M E T E R M E A S U R E M E N T I N F O R M A T I O N VKA Input VKA Input IK IK R1 IREF R2 VREF VREF FIGURE 10 — TEST CIRCUIT FOR VKA > VREF FIGURE 9 — TEST CIRCUIT FOR VKA = VREF VKA Input IOFF FIGURE 11 — TEST CIRCUIT FOR IOFF 8 Copyright © 1999 Rev. 1.4 6/99 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P D R O D U C T I O N A T A S H E E T TYPICAL CHARACTERISTICS 6 f = 0.1 to 10Hz IK = 10mA TA = 25°C (VN) Input Noise Voltage - (µV) 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 2 0 4 6 8 10 (t) Time - (s) FIGURE 12. — EQUIVALENT INPUT NOISE VOLTAGE OVER A 10-SECOND PERIOD 19.1V 1k 500µF VCC 910 2000µF VCC 1µF LX6431 (DUT) TLE2027 AV = 10V/mV 820 TLE2027 16k 16 160k 1µF 0.1µF VEE 2.2µF 16k 33k AV = 2V/V 1M CRO 33k VEE Test Circuit for 0.1Hz to 10Hz Equivalent Input Noise Voltage Copyright © 1999 Rev. 1.4 6/99 9 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P R O D U C T I O N D A T A S H E E T TYPICAL CHARACTERISTICS FIGURE 13. — SMALL-SIGNAL VOLTAGE AMPLIFICATION vs. FREQUENCY (AV) Voltage Amplification - (dB) 70 Output IK = 10mA TA = 25°C 60 IK 230 15k 50 9µF 40 30 8.25k 20 10 GND 0 Test Circuit for Voltage Amplification -10 1k 10k 100k 1M 10M (f) Frequency - (Hz) FIGURE 14. — REFERENCE IMPEDANCE vs. FREQUENCY (|zKA|) Reference Impedance - ( ) 100 Output IK = 1mA to 100mA TA = 25°C 1k IK 10 50 1 GND Test Circuit for Reference Impedance 0.1 1k 10k 100k 1M 10M (f) Frequency - (Hz) 10 Copyright © 1999 Rev. 1.4 6/99 PRODUCT DATABOOK 1996/1997 LX6431/LX6431A/LX6431B PRECISION PROGRAMMABLE REFERENCES P R O D U C T I O N D A T A S H E E T TYPICAL CHARACTERISTICS FIGURE 15. — PULSE RESPONSE 6 Output VIN - (V) 5 220 4 3 Pulse Generator f = 100kHz 2 50 (VKA) Output Voltage - (V) 1 0 3 GND 2 1 Test Circuit for Pulse Response 0 1 0 2 3 4 5 6 (t) Time - (µs) 50 180 Phase Shift GM/20 30 +35V 90 10 0 0 -10 -90 -30 -180 Phase Shift AVD - Differential Voltage Amplification - (dB) FIGURE 16. — DIFFERENTIAL VOLTAGE AMPLIFICATION vs. FREQUENCY To Network Analyzer as DUT Input Port with 10X Probe R3 1K C1 R1 100K 10µF R2 100K C2 10µF To Network Analyzer as DUT Output Port R4 2 DUT is bias at 30mA and 5V Test Setup for Measuring AVD vs. Frequency -50 1k 10k 100k 1M Frequency - (Hz) PRODUCTION DATA - Information contained in this document is proprietary to LinFinity, and is current as of publication date. This document may not be modified in any way without the express written consent of LinFinity. Product processing does not necessarily include testing of all parameters. Linfinity reserves the right to change the configuration and performance of the product and to discontinue product at any time. Copyright © 1999 Rev. 1.4 6/99 11