voltage regulators 1 AN1432NT variable output, low voltage operation shunt regulator overview the AN1432NT is a low voltage operation and posi- tive voltage variable output type shunt regulator. since the output voltage is adjustable from approximately 1.275 v to 14 v, it is suitable for a power supply of small-sized 3 v- system portable equipment. features ? high accuracy reference voltage: 1.275 v (allowance: 2%) ? low voltage operation: 1.275 v to 14 v applications ? office automation equipment and other small-sized por- table equipment note) the value of reference voltage and the package differ from an1432ms. block diagram ssip003-p-0000 unit: mm 5.00.2 5.10.2 13.50.5 (1.0) (1.0) 4.00.2 2.30.2 0.60.15 0.43 +0.1 ?0.05 2.54 0.43 +0.1 ?0.05 21 3 2 ref. i ref 3 a 1 k r 1 output constant current source reference voltage output transistor error amplifier r 2 v ref v ka v ka = v ref (1 + ) + i ref r 1 r 1 r 2
AN1432NT voltage regulators 2 pin no. description 1 k: cathode the pin for the combined use of the power source current supply of ic and the constant voltage output as the shunt regulator. an excessive current supplied to this pin is bypassed to the anode pin through the output transistor. 2 reference the reference voltage (1.275 v typical) pin. although the impedance is high under the normal using conditions, be careful that the impedance drops and current flo ws into the ic inside if a current or voltage is forced to apply from the outside. 3 anode the constant voltage reference pin of the shunt regulator, and the current from the cathode and reference flows out. usually grounded. pin descriptions absolute maximum ratings parameter symbol rating unit supply voltage v k 14.4 v reference voltage v ref 7v supply current i k 20 ma reference current i ref 50 a cathode - anode reverse current ? i ka ? 10 ma cathode - reference reverse current ? i kr ? 10 ma power dissipation * 2 p d 340 mw operating ambient temperature * 1 t opr ? 30 to + 85 c storage temperature * 1 t stg ? 55 to + 150 c note) 1. do not apply external currents or voltages to any pins not specifically mentioned. for circuit currents, ' + ' denotes current flowing into the ic and ' ? ' denotes current flowing out of the ic. 2. * 1: except for the power dissipation, operating ambient temperature and storage temperature, all ratings are for t a = 25 c. * 2: the value at t a = 85 c. recommended operating range parameter symbol range unit supply voltage v cc v ref to 14 v note) the value of reference voltage differs from an1432ms (surface mounting package).
voltage regulators AN1432NT 3 electrical characteristics at t a = 25 c parameter symbol conditions min typ max unit reference voltage v ref v ka = v ref , i k = 10 ma 1.249 1.275 1.30 v reference voltage fluctuation 1 ? v ref / ? v ref ? v ka 5 v, ? 1.9 3.5 mv/v ? v ka i k = 10 ma reference voltage fluctuation 2 ? v ref /5 v v ka 15 v, ? 1.0 2.0 mv/v ? v ka i k = 10 ma reference input current i ref r i = 10 k ? , i k = 10 ma ? 2.5 4.4 a minimum cathode current i k min v ka = v ref ? 290 350 a off time cathode current i k off v ka = 15 v, v ref = 0 v ?? 1.0 a dynamic impedance ? z ka ? v ka = v ref , f 1 khz, ? 0.1 0.5 ? i k = 1 ma to 10 ma parameter symbol conditions reference value unit reference voltage change ? v ref /v ka = v ref , i ka = 10 ma 3 mv with temperature ? t a 0 c t a + 70 c reference input current change ? i ref /r 1 = 10 k ? , i k = 10 ma 0.4 a with temperature ? t a 0 c t a + 70 c ? design reference data note) the characteristics listed below are theoretical values based on the ic design and are not guaranteed. application notes 1. p d ? t a curve of ssip003-p-0000 p d ? t a power dissipation p d (w) ambient temperature t a ( c) 0 0 0.2 0.4 0.6 0.8 1.0 0 20 40 60 85 80 100 120 140 160 independent ic without a heat sink r th(j-a) = 190 c/w p d = 658mw (25 c)
AN1432NT voltage regulators 4 application notes (continued) 2. main characteristics v ref1 temperature characteristic i ref temperature characteristic ? v ref temperature characteristic i k off temperature characteristic z ka temperature characteristic 1.266 1.268 1.282 v ref1 (v) 1.270 1.272 1.274 1.276 1.278 1.280 ? 25 0 50 25 75 100 t a ( c) 2.0 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 t a ( c) i ref ( a) ? 25 0 50 25 75 100 3.0 0 0.5 1.0 1.5 2.0 2.5 t a ( c) ? v ref (mv) ? 25 0 50 25 75 100 0 20 40 60 80 100 120 140 160 180 t a ( c) i k off (na) ? 25 0 50 25 75 100 0.6 0.1 0.2 0.3 0.4 0.5 0 t a ( c) z ka ( ? ) ? 25 0 50 25 75 100
voltage regulators AN1432NT 5 application circuit example this circuit amplifies the error voltage of the secondary side output voltage in the insulation type switching power supply, then transfers it to the primary side via a photocoupler. replaceable with the conventional products (an1431m, an1431t). (primary side) to primary side control ic (secondary side) v out AN1432NT application notes (continued) 2. main characteristics (continued) gain ? phase characteristics gain ? phase characteristics measurement circuit ripple rejection ratio ripple rejection ratio measurement circuit voltage gain g vol (db) 60 10m 100k 1k 1m 10k 100 10 frequency f (hz) 0 10 20 30 40 50 phase delay ( ) ? 270 ? 225 ? 360 ? 315 ? 180 ? 135 ? 90 ? 45 0 phase gain ripple rejection ratio rr (db) 1m 100k 10k 100 1k frequency f (hz) ? 60 ? 50 ? 80 ? 70 ? 40 ? 30 ? 20 ? 10 0 1 k ? 10 f i k 10 ma 50 ? out 15 k ? 220 ? 10 f 8.2 k ? i k 10 ma
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