Datasheet OP295, OP495 (Analog Devices) - 12

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OP295/OP495 5V 5V IL < 50mA 8 5V MJE 350 R1 2 VO 17.8kΩ VDD RFB + + D V 44.2kΩ IN 100µF 1% 3 1 8 VO = (4.096V) 5V TO 3.2V 1.23V V 3 I + 4096 OUT DAC8043 REF 8 + 3 1 1 30.9kΩ GND CLK SRI LD 2 – 4 OP295/ 1% AD589 4 7 6 5 OP495 – 2 4 1/2 OP295/ 1000pF R2 R4 OP495 41.2kΩ 100kΩ DIGITAL 1.235V CONTROL R3
27
5kΩ 43kΩ
-0 25
AD589
-0 31
TOTAL POWER DISSIPATION = 1.6mW
31 03 0 03 0 Figure 29. 3 V Low Dropout Voltage Regulator Figure 27. A 5 V 12-Bit DAC with 0 V to 4.095 V Output Swing Figure 30 shows the regulator’s recovery characteristic when its
4 mA TO 20 mA CURRENT-LOOP TRANSMITTER
output underwent a 20 mA to 50 mA step current change. Figure 28 shows a self-powered 4 mA to 20 mA current-loop transmitter. The entire circuit floats up from the single-supply
2V
(12 V to 36 V) return. The supply current carries the signal
100 50mA
within the 4 mA to 20 mA range. Thus, the 4 mA establishes the
90 STEP
baseline current budget within which the circuit must operate.
CURRENT CONTROL
This circuit consumes only 1.4 mA maximum quiescent
WAVEFORM
current, making 2.6 mA of current available to power additional
20mA
signal conditioning circuitry or to power a bridge circuit.
NULL ADJ REF02 6 2 OUTPUT + 10 100kΩ GND SPAN ADJ 10-TURN 4 0% 5V 20mV 1ms 10kΩ 1.21MΩ 100Ω
028
10-TURN 1% – VIN 8 3 +
00331-
0V + 3V 220Ω 12V 182kΩ
Figure 30. Output Step Load Current Recovery
1 TO 1% 36V 2N1711 2 – 4 1/2 LOW DROPOUT, 500 mA VOLTAGE REGULATOR OP295/ 4mA OP495 TO WITH FOLDBACK CURRENT LIMITING 20mA 220pF RL
Adding a second amplifier in the regulation loop, as shown in
100Ω
6
HP 100kΩ 100Ω
Figure 31, provides an output current monitor as well as -02
5082-2800 1% 1%
31 03 0 foldback current limiting protection. Figure 28. 4 mA to 20 mA Current Loop Transmitter
IO (NORM) = 0.5A RSENSE I 3 V LOW DROPOUT LINEAR VOLTAGE REGULATOR IRF9531 O (MAX) = 1A 0.1Ω 1/4W S D 5V VO
Figure 29 shows a simple 3 V voltage regulator design. The
+ 6V G 210kΩ 205kΩ
regulator can deliver 50 mA load current while allowing a
– 1% 1%
0.2 V dropout voltage. The OP295/OP495 rail-to-rail output
8 + 5 1N4148
swing drives the MJE350 pass transistor without requiring
7 A2 – 6
special drive circuitry. At no load, its output can swing less than
1/2 OP295/ 45.3kΩ 45.3kΩ
the pass transistor’s base-emitter voltage, turning the device
OP495 1% 1% 100kΩ
nearly off. At full load, and at low emitter-collector voltages, the
5% 0.01µF
transistor beta tends to decrease. The additional base current is
+ 3 124kΩ 1 A1 124kΩ
easily handled by the OP295/OP495 output.
1/2 1% 1% 4 – 2 OP295/
The amplifier servos the output to a constant voltage, which
OP495
feeds a portion of the signal to the error amplifier.
REF43 2.5V
29
2 6
0 1- Higher output current, to 100 mA, is achievable at a higher
4
33 00 dropout voltage of 3.8 V. Figure 31. Low Dropout, 500 mA Voltage Regulator with Foldback Current Limiting Rev. G | Page 12 of 16 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION PIN CONFIGURATIONS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ELECTRICAL CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS APPLICATIONS RAIL-TO-RAIL APPLICATION INFORMATION LOW DROP-OUT REFERENCE LOW NOISE, SINGLE-SUPPLY PREAMPLIFIER DRIVING HEAVY LOADS DIRECT ACCESS ARRANGEMENT SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER SINGLE-SUPPLY RTD THERMOMETER AMPLIFIER COLD JUNCTION COMPENSATED, BATTERY-POWERED THERMOCOUPLE AMPLIFIER 5 V ONLY, 12-BIT DAC THAT SWINGS 0 V TO 4.095 V 4 mA TO 20 mA CURRENT-LOOP TRANSMITTER 3 V LOW DROPOUT LINEAR VOLTAGE REGULATOR LOW DROPOUT, 500 mA VOLTAGE REGULATOR WITH FOLDBACK CURRENT LIMITING SQUARE WAVE OSCILLATOR SINGLE-SUPPLY DIFFERENTIAL SPEAKER DRIVER HIGH ACCURACY, SINGLE-SUPPLY, LOW POWER COMPARATOR OUTLINE DIMENSIONS ORDERING GUIDE