8.2.1 Design Requirements

Table 1 lists the design parameters for this example.

8.2.2 Detailed Design Procedure

Given that the transfer function of this circuit is:

Equation 1.

the output can be set between 0.2 V and the breakdown voltage of the IC by selecting an appropriate value for R2. The circuit regulates for input voltages within a saturation drop of the output (typically 0.4 V at 20 mA and 0.15 V at 5 mA). The regulator is protected from shorts or overloads by current limiting and thermal shutdown.

Typical regulation is about 0.05% load and 0.003%/V line. A substantial improvement in regulation can be effected by connecting the operational amplifier as a follower and setting the reference to the desired output voltage. This has the disadvantage that the minimum input-output differential is increased to a little more than a diode drop. If the operational amplifier were connected for a gain of 2, the output could again saturate. But this requires an additional pair of precision resistors.

The regulator in Figure 36 could be made adjustable to zero by connecting the operational amplifier to a potentiometer on the reference output. This has the disadvantage that the regulation at the lower voltage settings is not as good as it might otherwise be.

8.2.3 Application Curve

Figure 37. Frequency Response

8.3.1 Operational Amplifier Offset Adjustment

Figure 38. Standard

Figure 40. Limited Range With Boosted Reference

Figure 39. Limited Range

8.3.2 Positive Regulators

Figure 41. Low Voltage

Use only electrolytic output capacitors.

Figure 43. Zero Output

Required For Capacitive Loading

Figure 45. Shunt Regulator

Figure 47. Precision Regulator

Figure 49. HV Regulator

*800°C Threshold Is Established By Connecting Balance To V_REF.

Figure 51. Flame Detector

Figure 53. Remote Amplifier

Figure 55. Transmitter for Bridge Sensor

Figure 57. Resistance Thermometer Transmitter

200°C≤T_p≤700°C
1 mA≤I_OUT≤5 mA
†Gain Trim

Figure 59. Thermocouple
Transmitter

Figure 61. Battery-level Indicator

Flashes Above 1.2V

Rate Increases With

Voltage

Figure 63. Single-cell Voltage Monitor

  INPUT

10 mV, 100nA

FULL-SCALE

Figure 65. Meter Amplifier

1≤λ/λ₀≤10⁵

Figure 67. Light Meter

†Controls “Loop Gain”

*Optional Frequency Shaping

Figure 69. Isolated Voltage Sensor

Figure 42. Best Regulation

Figure 44. Current Regulator

*Electrolytic

Figure 46. Negative Regulator

*V_OUT=10⁻⁴ R3

Figure 48. Laboratory Power Supply

Figure 50. Protected HV Regulator

*Provides Hysteresis

Figure 52. Light Level Sensor

Figure 54. Remote Thermocouple Amplifier

10 mA≤I_OUT≤50 mA

500°C≤T_P≤1500°C

*Gain Trim

Figure 56. Precision Thermocouple Transmitter

††Level-shift Trim
 *Scale Factor Trim
 †Copper Wire Wound

Figure 58. Optical Pyrometer

1 mA≤I_OUT≤5 mA

‡50 μA≤I_D≤500 μA

††Center Scale Trim

†Scale Factor Trim

*Copper Wire Wound

Figure 60. Logarithmic Light Sensor

Figure 62. Battery-threshold Indicator

Flash Rate Increases

Above 6V and Below 15V

Figure 64. Double-ended Voltage Monitor

*Trim For Span

†Trim For Zero

Figure 66. Thermometer

Z_OUT∼680Ω @ 5 kHz

A_V≤1k

f₁∼100 Hz

f₂∼5 kHz

R_L∼500

*Max Gain Trim

Figure 68. Microphone Amplifier

Figure 70. Light-Level Controller

8.3.3 Reference and Internal Regulator

Figure 71. Reference and Internal Regulator