ZHCS959D June   2012  – September 2016 OPA4188

PRODUCTION DATA.  

  1. 特性
  2. 应用范围
  3. 说明
  4. 修订历史记录
  5. Zero-Drift Amplifier Portfolio
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: High-Voltage Operation, VS = ±4 V to ±18 V (VS = 8 V to 36 V)
    6. 7.6 Electrical Characteristics: Low-Voltage Operation, VS = ±2 V to < ±4 V (VS = +4 V to < +8 V)
    7. 7.7 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Phase-Reversal Protection
      2. 8.3.2 Capacitive Load and Stability
      3. 8.3.3 Electrical Overstress
      4. 8.3.4 EMI Rejection
    4. 8.4 Device Functional Modes
  9. Applications and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Operating Characteristics
    2. 9.2 Typical Applications
      1. 9.2.1 Second Order Low Pass Filter
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curve
      2. 9.2.2 Discrete INA + Attenuation for ADC With a 3.3-V Supply
      3. 9.2.3 RTD Amplifier With Linearization
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12器件和文档支持
    1. 12.1 文档支持
      1. 12.1.1 器件支持
        1. 12.1.1.1 开发支持
          1. 12.1.1.1.1 TINA-TI(免费软件下载)
          2. 12.1.1.1.2 TI 高精度设计
          3. 12.1.1.1.3 WEBENCH® Filter Designer
      2. 12.1.2 相关文档 
    2. 12.2 商标
    3. 12.3 静电放电警告
    4. 12.4 Glossary
  13. 13机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

Detailed Description

Overview

The OPA4188 operational amplifier combines precision offset and drift with excellent overall performance, making the device ideal for many precision applications. The precision offset drift of only 0.085 μV per degree Celsius provides stability over the entire temperature range. In addition, the device offers excellent overall performance with high CMRR, PSRR, and AOL. As with all amplifiers, applications with noisy or high-impedance power supplies require decoupling capacitors close to the device pins. In most cases, 0.1-μF capacitors are adequate. The OPA4188 device is developed using TI's proprietary auto-zero architecture shown in Functional Block Diagram. The internal synchronous notch filter removes switching noise from the CHOP1 and CHOP2 stages, resulting in a low noise density of 8.8 nV/Hz, low input offset voltage maximum of only 25 µV. Input offset drift maximum of only 0.085 µV/°C allows for calibration free system design.

Functional Block Diagram

OPA4188 ai_zerodrift_topology_sbos641.gif

Feature Description

Phase-Reversal Protection

The OPA4188 device has an internal phase-reversal protection. Many op amps exhibit a phase reversal when the input is driven beyond its linear common-mode range. This condition is most often encountered in noninverting circuits when the input is driven beyond the specified common-mode voltage range, causing the output to reverse into the opposite rail. The OPA4188 input prevents phase reversal with excessive common-mode voltage. Instead, the output limits into the appropriate rail. This performance is shown in Figure 39.

OPA4188 tc_no_phase_bos525.gif Figure 39. No Phase Reversal

Capacitive Load and Stability

The OPA4188 dynamic characteristics have been optimized for a range of common operating conditions. The combination of low closed-loop gain and high capacitive loads decreases the amplifier phase margin and can lead to gain peaking or oscillations. As a result, heavier capacitive loads must be isolated from the output. The simplest way to achieve this isolation is to add a small resistor (for example, ROUT equal to 50 Ω) in series with the output. Figure 40 and Figure 41 illustrate graphs of small-signal overshoot versus capacitive load for several values of ROUT. For details of analysis techniques and application circuits, see Feedback Plots Define Op Amp AC Performance, available for download from www.ti.com.

OPA4188 tc_sm_oshoot-cl_pos_bos525.gif
Figure 40. Small-Signal Overshoot versus Capacitive Load (100-mV Output Step)
OPA4188 tc_sm_oshoot-cl_neg_bos525.gif
Figure 41. Small-Signal Overshoot vs Capacitive Load (100-mV Output Step)

Electrical Overstress

Designers often ask questions about the capability of an operational amplifier to withstand electrical overstress. These questions tend to focus on the device inputs, but may involve the supply voltage pins or even the output pin. Each of these different pin functions have electrical stress limits determined by the voltage breakdown characteristics of the particular semiconductor fabrication process and specific circuits connected to the pin. Additionally, internal electrostatic discharge (ESD) protection is built into these circuits to protect them from accidental ESD events both before and during product assembly.

These ESD protection diodes also provide in-circuit, input overdrive protection, as long as the current is limited to 10 mA as stated in the Absolute Maximum Ratings. Figure 42 shows how a series input resistor may be added to the driven input to limit the input current. The added resistor contributes thermal noise at the amplifier input and its value should be kept to a minimum in noise-sensitive applications.

OPA4188 ai_input_current_bos525.gif Figure 42. Input Current Protection

An ESD event produces a short-duration, high-voltage pulse that is transformed into a short-duration, high-current pulse as it discharges through a semiconductor device. The ESD protection circuits are designed to provide a current path around the operational amplifier core to prevent it from being damaged. The energy absorbed by the protection circuitry is then dissipated as heat.

When the operational amplifier connects into a circuit, the ESD protection components are intended to remain inactive and not become involved in the application circuit operation. However, circumstances may arise where an applied voltage exceeds the operating voltage range of a given pin. Should this condition occur, there is a risk that some of the internal ESD protection circuits may be biased on, and conduct current. Any such current flow occurs through ESD cells and rarely involves the absorption device.

If there is an uncertainty about the ability of the supply to absorb this current, external Zener diodes may be added to the supply pins. The Zener voltage must be selected such that the diode does not turn on during normal operation. However, its Zener voltage should be low enough so that the Zener diode conducts if the supply pin begins to rise above the safe operating supply voltage level.

EMI Rejection

The OPA4188 device uses integrated electromagnetic interference (EMI) filtering to reduce the effects of EMI interference from sources such as wireless communications and densely-populated boards with a mix of analog signal chain and digital components. EMI immunity can be improved with circuit design techniques; the OPA4188 benefits from these design improvements. Texas Instruments has developed the ability to accurately measure and quantify the immunity of an operational amplifier over a broad frequency spectrum extending from 10 MHz to 6 GHz. Figure 43 shows the results of this testing on the OPA4188 device. Detailed information can also be found in EMI Rejection Ratio of Operational Amplifiers available for download from www.ti.com.

OPA4188 tc_emirr-frq_bos525.gif Figure 43. EMIRR Testing

Device Functional Modes

The OPA4188 device has a single functional mode that is operational when the power-supply voltage is greater than 4 V (±2 V). The maximum power supply voltage for the OPA4188 is 36 V (±18 V).