ZR2431. V Z V ref. G nd ADJUSTABLE PRECISION ZENER SHUNT REGULATOR ISSUE 3 DECEMBER 1997 DEVICE DESCRIPTION FEATURES APPLICATIONS SCHEMATIC DIAGRAM

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1 ADJUSTABLE PRECISION ENER SHUNT REGULATOR ISSUE 3 DECEMBER DEICE DESCRIPTION The 431 is a three terminal adjustable shunt regulator offering excellent temperature stability and output current handling capability up to 25mA. The output voltage may be set to any chosen voltage between 1.24 and 15 volts by selection of two external divider resistors. The devices can be used as a replacement for zener diodes in many applications requiring an improvement in zener performance. The 431 is particularly used in the feedback control loop of switch mode power supplies. In this application the device 1.24 volt reference enables the generation of low voltage supplies, typically 3.3 volts or 3 volts. SCHEMATIC DIAGRAM FEATURES Surface mount SOT23, SOT223, SOT89 and SO8 packages TO92 package 2.5% and 1% tolerance Maximum temperature coefficient 52 ppm/ C Temperature compensated for operation over the full temperature range Programmable output voltage 1µA to 25mA current sink capability Low output noise APPLICATIONS Shunt regulator Series regulator oltage monitor Over voltage/ under voltage protection Switch mode power supplies ref G nd 4-154

2 431 ABSOLUTE MAXIMUM RATING Power Dissipation (Tamb=25 C, Cathode oltage () 15 T jmax=15 C) Cathode Current 5mA SOT23 33mW Operating Temperature -4 to 85 C SOT223 2W Storage Temperature -55 to 125 C SO8 78mW Recommended Operating Conditions TO92 78mW Min Max SOT89 1.5W Cathode oltage REF 15 Cathode Current 1µA 25mA ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):t amb =25 C PARAMETER Reference oltage 2.5% 1.% Deviation of Reference oltage over Temperature Ratio of the change in Reference oltage to the Change in Cathode oltage SYMBOL MIN ALUE TYP MAX ref UNITS CONDITIONS I L =1mA (Fig1), = ref dev m I L =1mA, = ref T a =full range (Fig1) ref.5 2. m/ from ref to 1 I =1mA (Fig2) Reference Current I ref µa =1k, =O/C, l L =1mA (Fig2) Deviation of Reference Current over Temperature Minimum Cathode Current for Regulation I ref.2.2 µa =1k, =O/C, I L =1mA T a =full range (Fig2) I min 3 1 µa Off-state Current I off 1 3 µa =15, ref = (Fig3) Dynamic Output Impedance R.25 2 Ω = ref (Fig1), f=hz, I L =1mA Deviation of reference input voltage, dev, is defined as the maximum variation of the reference input voltage over the full temperature range. The average temperature coefficient of the reference input voltage, is defined as: max dev x 1 ref (ppm C)= ref (T1 T2) The dynamic output impedance, Rz, is defined as: R = I min When the device is programmed with two external resistors, and, (fig 2), the dynamic output impedance of the overall dev = max - min circuit, R, is defined as: R =R z (1+ ) With a capacitance of greater than 1pF between cathode and anode, minimum cathode current must be.2ma. T1 T2 Temperature 4-155

3 431 TYPICAL CHARACTERISTICS TYPICAL CHARACTERISTICS Reference Current (na) 14 = z Iz=1mA Temperature ( C) Reference Current v Temperature Change in Reference Output oltage(m) Cathode oltage () Iz = 1mA Change in v Cathode oltage Minimum Cathode Current(µA) = z Temperature ( C) Cathode Current v Temperature Dynamic Impedance (Ω) = z 1k 1k 1k Frequency (Hz) Dynamic Impedance v Frequency 1mA 1mA Reference oltage () Iz=1mA Temperature ( C) Reference oltage v Temperature Power Dissipation (W) SOT 89 SOT23 SO8/TO92 SOT Ambient Temprature ( C) Power Dissipation Derating 4-156

4 TYPICAL CHARACTERISTICS 431 Open Loop oltage Gain (db) 6 Iz = 1mA k 1k 1k 1M Frequency (Hz) Gain v Frequency I 47k 24Ω 1µF + 47k - I = 1mA, TA = 25 C Test Circuit for Open Loop oltage Gain 2. Single Pulse Monitor 12Ω oltage Swing () Repetitive Pulse Time (us) z INPUT Pulse Response TA = 25 C Pulse Generator 5Ω Test Circuit for Pulse Response < < 2, I = 1mA, TA = 25 C Cathode Current(mA) STABLE UNSTABLE STABLE 1µF 15Ω I 1k 1p 1p 1n 1n.1µ 1µ 1µ Load Capacitance(F) Stablity Boundary Conditions Test Circuit for Stability Boundary Conditions 4-157

5 431 DC TEST CIRCUITS IL IL Iref I Iref I I zoff 1µF 1µF 1µF ref ref Fig 1 Test Circuit for z = ref Fig 2 Test Circuit for z > ref Fig 3 Test Circuit for Off State current 4-158

6 431 APPLICATION CIRCUITS + out + out out = 1 + SHUNT REGULATOR out = 1 + HIGHER CURRENT SHUNT REGULATOR + SR*** + out In Out 3 Common out MIN = + reg out = 1 + OUTPUT CONTROL OF A THREE TERMINAL FIXED REGULATOR.1µF out = 1 + SERIES REGULATOR out + + INPUT OUTPUT A B OUTPUT = 2.5 TH 2 on off = + A B Low limit = 1 + B B SINGLE SUPPLY COMPARATOR WITH TEMPERATURE COMPENSATED THRESHOLD High limit = 1 + A A OER OLTAGE / UNDER OLTAGE PROTECTION CIRCUIT 4-159

7 431 CONNECTION DIAGRAMS SO8 Package Suffix N8 SOT223 Package Suffix G Top iew Top iew Pin 4 floating or connected to pin 2 SOT23 Package Suffix F TO92 Package Suffix C Top iew Bottom iew SOT89 Package Suffix Top iew ORDERING INFORMATION Part Number Package Tol Part Mark % 431N82 SO N81 SO G2 SOT G1 SOT F2 SOT D 431F1 SOT E 4312 SOT D 4311 SOT E 431C2 TO C1 TO

ZR431 V Z. V ref. G nd ADJUSTABLE PRECISION ZENER SHUNT REGULATOR ISSUE 5 DECEMBER 2002 DEVICE DESCRIPTION FEATURES APPLICATIONS SCHEMATIC DIAGRAM

ZR431 V Z. V ref. G nd ADJUSTABLE PRECISION ZENER SHUNT REGULATOR ISSUE 5 DECEMBER 2002 DEVICE DESCRIPTION FEATURES APPLICATIONS SCHEMATIC DIAGRAM ADJUSTABLE PRECISION ZENER SHUNT REGULATOR ISSUE 5 DECEMBER 22 DEVICE DESCRIPTION The ZR431 is a three terminal adjustable shunt regulator offering excellent temperature stability and output current handling