Beschreibung

The OPA2188 operational amplifier uses TI proprietary auto-zeroing techniques to provide low offset voltage (25 μV, maximum), and near zero-drift over time and temperature. This miniature, highprecision, low quiescent current amplifier offers high input impedance and rail-to-rail output swing within 15 mV of the rails. The input common-mode range includes the negative rail. Either single or dual supplies can be used in the range of 4 V to 36 V (±2 V to ±18 V).
The OPA2188 device is available in MSOP-8 and SO-8 packages. The device is specified for operation from–40°C to +105°C.

 

Eigenschaften

• LowOffset Voltage: 25 μV (Maximum)
• Zerø-Drift: 0.03 μV/°C
• Excellent DC Precision:
PSRR: 142 dB
CMRR: 146 dB
Open-Loop Gain: 136 dB
• Gain Bandwidth: 2 MHz
• Quiescent Current: 475 μA (Maximum)
• WideSupply Range: ±2 V to ±18 V
• Rail-to-Rail Output: Input Includes Negative Rail
• RFIFiltered Inputs
• MicroSIZE Packages

 

Anwendungen

• Bridge Amplifiers
• Strain Gauges
• Test Equipment
• Transducer Applications
• Temperature Measurement
• Electronic Scales
• Medical Instrumentation
• Resistance Temperature Detectors
• Precision Active Filters

 

Übersicht

The OPA2188 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/°C 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.

 

EMI Rejection

The OPA2188 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 OPAx188 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.

 

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.

 

Feature Description (continued)

An ESD event produces a short duration, high-voltage pulse that is transformed into a short duration, highcurrent 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 must be low enough so that the zener diode conducts if the supply pin begins to rise above the safe operating supply voltage level.