Texas Instruments PGA205BU

Overview

PGA205BU from Texas Instruments (formerly Burr-Brown) is a digitally programmable gain instrumentation amplifier (PGIA) with fixed binary gains of 1, 2, 4, and 8 V/V, ±40V input over-voltage protection, 50µV max input offset voltage, and operation from ±4.5V to ±18V supplies. It serves as the front-end signal conditioner in precision low-speed data acquisition systems where sensor-level signals require scalable amplification before ADC conversion.

For engineers reviewing the PGA205BU datasheet, PGA205BU pinout, PGA205BU application, or PGA205BU equivalent, key selection considerations include its 80–112 dB common-mode rejection across gain settings, 100 kHz bandwidth at G=8, 0.7 V/µs slew rate, and compatibility with TTL/CMOS logic without external level-shifting - all critical for medical sensor interfaces and industrial analog input modules.

Technical Context

The PGA205BU integrates three high-precision op amps (A1, A2, A3) in an instrumentation topology with digitally selected thin-film feedback resistors (25kΩ × 4). Gain is set via two unbuffered TTL/CMOS-compatible address inputs (A0, A1), with no latch required - changes take effect within 28 µs (0.01% settling at G=8).

It features dual over-voltage protection circuits per input, laser-trimmed input stage offset (±50 µV max), and output referenced to a dedicated Ref pin - requiring low-impedance grounding to maintain CMR. The internal digital ground (pin 14) sinks 1.3 mA and must be routed separately from analog ground to avoid coupling noise into the signal path.

Key Specifications

Pinout & Package

SOL-16 surface-mount package (SOIC-DW, 16-pin), 10.3 mm × 7.5 mm body, 1.27 mm pitch, RoHS-compliant, MSL Level-3 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar programmable-gain instrumentation amplifier applications.

Compared with INA128UA and AD8253ARMZ, the PGA205BU uniquely balances TTL/CMOS simplicity, robust ±40V input protection, and SOIC-16 manufacturability - making it optimal for cost-sensitive, medium-speed industrial and medical front-ends where digital control must be hardware-simple and fault-tolerant.

Availability

PGA205BU is available at Aetrix Electronics and suitable for medical sensor interfaces, industrial analog input modules, portable test equipment, and data acquisition front-ends requiring stable component supply across long production lifecycles.

Supply support for PGA205BU includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments acquired Burr-Brown in 2000 and maintains full production and support for legacy precision analog products including the PGA204/205 family.

The PGA205BU belongs to TI's precision instrumentation amplifier product line, designed specifically for DC-coupled, low-frequency signal conditioning in measurement systems where gain flexibility, input protection, and long-term stability are essential.

FAQ

What gain settings does the PGA205BU support?

The PGA205BU supports four discrete binary gain settings: 1 V/V, 2 V/V, 4 V/V, and 8 V/V. These are selected using two digital address inputs (A0 and A1) with standard TTL/CMOS logic levels. Unlike the PGA204BU (which offers 1/10/100/1000 V/V), the PGA205BU is optimized for moderate-gain applications where finer scaling and lower noise at mid-range gains are prioritized. Each gain setting is internally laser-trimmed for accuracy.

Does the PGA205BU require an external logic supply voltage?

No, the PGA205BU does not require an external logic supply voltage. Its digital inputs (A0 and A1) are compatible with standard TTL and CMOS logic levels referenced to its own digital ground (pin 14), which can be tied to system ground or any potential between V– and (V+ – 4V). This eliminates the need for level shifters or auxiliary logic rails - simplifying design and reducing component count in mixed-signal systems using the PGA205BU.

How is the output reference handled on the PGA205BU?

The PGA205BU uses a dedicated Ref pin (pin 10) to define its output reference point. The output voltage VO is referenced to this pin, not to ground or supply rails. For optimal common-mode rejection (>100 dB), Ref must be connected to a low-impedance ground (≤5 Ω). Alternatively, a precision voltage can be applied to Ref to introduce calibrated offset - e.g., to center a bipolar sensor output within a unipolar ADC range - without degrading CMRR, provided the driving source has low output impedance.

Can the PGA205BU operate from a single supply?

No, the PGA205BU is specified only for dual-supply operation (±4.5V to ±18V). Its internal architecture relies on symmetrical rails to bias the input and output stages correctly. Attempting single-supply operation (e.g., 0V and +15V) will result in undefined behavior, saturation, or failure to meet datasheet specifications. For single-supply applications, consider TI's PGA308 or ADI's AD8251 - neither of which are direct replacements for the PGA205BU.

What is the purpose of pins 6 and 7 (VOS Adj) on the PGA205BU?

Pins 6 and 7 on the PGA205BU are dedicated to input offset voltage trimming. They connect to an external potentiometer (200kΩ–1MΩ) to null the input-stage offset voltage (V_OSI) - the dominant contributor to total offset at high gains. Best practice is to configure the PGA205BU at G=8, ground both inputs, and adjust the pot until VO = 0 V. This procedure improves drift performance and avoids introducing temperature-dependent errors that occur when trimming system-level offsets instead of intrinsic device offset.