link to page 25 link to page 25 Data SheetREF19x Series+VBAT2+VSC2R10.1µFU1R3R61.1MΩ3 REF195 610MΩ100ΩQ1(SEE TABLE)2N39045.000V4C13 +0.1µF7642 –U32AD820U2+C3361µFR2REF195(SEE TABLE)100kΩR44900kΩC4R5V0.1µF 100kΩS, VBATVOUT 30 COMMON -0 COMMON 71 03 0 Figure 32. Fail-Safe 5 V Reference For V 100 Ω S levels lower than the lower threshold, the output of U3 is low, thus U2 and Q1 are off and U1 is on. For VS levels higher REF19510 μ F than the upper threshold, the situation reverses, with U1 off and 26 both U2 and Q1 on. In the interest of battery power conserva- ++10 μ F41 μ F tion, all of the comparison switching circuitry is powered from VS and is arranged so that when VS fails, the default output 57k Ω 1%0.1 μ F comes from U1. For the R1 to R3 values, as shown in Figure 32, lower/upper VS 3 +4 switching thresholds are approximately 5.5 V and 6 V, respec- 1/412N2222OP492 tively. These can be changed to suit other VS supplies, as can the 10k Ω 0.1 μ F2 –111% REF19x devices used for U1 and U2, over a range of 2.5 V to 5 V of output. U3 can operate down to a VS of 3.3 V, which is 500 Ω generally compatible with all REF19x family devices. 0.1%LOW POWER, STRAIN GAGE CIRCUIT10k Ω As shown in Figure 33, the REF19x family of references can be 1%0.01 μ F used in conjunction with low supply voltage operational ampli- 20k Ω 1% fiers, such as the OP492 or the OP747, in a self-contained strain 20k Ω 13– gage circuit in which the REF195 is used as the core. Other 1/41%146– references can be easily accommodated by changing circuit OP4921/412+7OUTPUTOP492 element values. The references play a dual role, first as the 2.21k Ω 10k Ω 5+1% voltage regulator to provide the supply voltage requirements of the strain gage and the operational amplifiers, and second as a 9–20k Ω precision voltage reference for the current source used to 1/41%8 stimulate the bridge. A distinct feature of the circuit is that it OP49220k Ω 10+ can be remotely controlled on or off by digital means via 1% 00371-031 the SLEEP pin. Figure 33. Low Power, Strain Gage Circuit Rev. L | Page 25 of 28 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION TEST PINS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ELECTRICAL CHARACTERISTICS—REF191 @ TA = 25°C ELECTRICAL CHARACTERISTICS—REF191 @ −40°C ≤ +85°C ELECTRICAL CHARACTERISTICS—REF191 @ −40°C ≤ TA ≤ +125°C ELECTRICAL CHARACTERISTICS—REF192 @ TA = 25°C ELECTRICAL CHARACTERISTICS—REF192 @ −40°C ≤ TA ≤ +85°C ELECTRICAL CHARACTERISTICS—REF192 @ −40°C ≤ TA ≤ +125°C ELECTRICAL CHARACTERISTICS—REF193 @ TA = 25°C ELECTRICAL CHARACTERISTICS—REF193 @ −40°C ≤ TA ≤ +85°C ELECTRICAL CHARACTERISTICS—REF193 @ TA ≤ −40°C ≤ +125°C ELECTRICAL CHARACTERISTICS—REF194 @ TA = 25°C ELECTRICAL CHARACTERISTICS—REF194 @ −40°C ≤ TA ≤ +85°C ELECTRICAL CHARACTERISTICS—REF194 @ −40°C ≤ TA ≤ +125°C ELECTRICAL CHARACTERISTICS—REF195 @ TA = 25°C ELECTRICAL CHARACTERISTICS—REF195 @ −40°C ≤ TA ≤ +85°C ELECTRICAL CHARACTERISTICS—REF195 @ −40°C ≤ TA ≤ +125°C ELECTRICAL CHARACTERISTICS—REF196 @ TA = 25°C ELECTRICAL CHARACTERISTICS—REF196 @ −40°C ≤ TA ≤ +85°C ELECTRICAL CHARACTERISTICS—REF196 @ −40°C ≤ TA ≤ +125°C ELECTRICAL CHARACTERISTICS—REF198 @ TA = 25°C ELECTRICAL CHARACTERISTICS—REF198 @ −40°C ≤ TA ≤ +85°C ELECTRICAL CHARACTERISTICS—REF198 @ −40°C ≤ TA ≤ 125°C ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS APPLICATIONS INFORMATION OUTPUT SHORT-CIRCUIT BEHAVIOR DEVICE POWER DISSIPATION CONSIDERATIONS OUTPUT VOLTAGE BYPASSING SLEEP MODE OPERATION BASIC VOLTAGE REFERENCE CONNECTIONS MEMBRANE SWITCH-CONTROLLED POWER SUPPLY SOLDER HEAT EFFECT CURRENT-BOOSTED REFERENCES WITH CURRENT LIMITING NEGATIVE PRECISION REFERENCE WITHOUT PRECISION RESISTORS STACKING REFERENCE ICs FOR ARBITRARY OUTPUTS PRECISION CURRENT SOURCE SWITCHED OUTPUT 5 V/3.3 V REFERENCE KELVIN CONNECTIONS FAIL-SAFE 5 V REFERENCE LOW POWER, STRAIN GAGE CIRCUIT OUTLINE DIMENSIONS ORDERING GUIDE
Купить REF192ESZ-REEL7 на РадиоЛоцман.Цены — от 69 до 2 530 ₽
