ADA4351-2 Programmable Gain Transimpedance Amplifier (PGTIA)

ADI's ADA4351-2 is a compact, monolithic, dual-channel, precision, programmable gain transimpedance amplifier (PGTIA). It is a breakthrough solution for precisely measuring small currents over a wide dynamic range. The precision of the ADA4351-2 over a wide temperature range of -40°C to +125°C enables users to perform one calibration of the end equipment at room temperature, thereby saving test time and cost. The ADA4351-2 integrates two low off leakage current switches per channel, and the gain is programmable using two user-selectable external resistors to provide a flexible, fully functional, compact PGTIA solution. Separate analog and digital supplies allow the amplifier of the ADA4351-2 to operate on bipolar supplies, while the integrated logic level shifting allows the digital interface to remain ground referenced. Additionally, with its robust output stage and low noise, the ADA4351-2 can directly drive 16-bit precision analog-to-digital converters (ADCs, such as AD4696), providing a complete analog front-end (AFE) to address the most challenging precision current measurement applications.

The ADA4351-2 is offered in a 3 mm x 3 mm LFCSP, reducing the printed circuit board (PCB) area by up to 70% relative to a discrete design using standalone operational amplifiers (op amps) and switches. No exposed pad (EPAD) on the back side of the LFCSP eliminates the need for vias and allows routing on all layers of the PCB beneath the device to further reduce the board area and provide the most compact PGTIA and AFE solution.

The EVAL-ADA4351-2EBZ 4-layer printed circuit evaluation board is designed to help users evaluate the ADA4351-2. Its dimensions are 2.9 inches x 2.25 inches, and it comes populated with key components that allow users to run and evaluate the board quickly and with relative ease. The EVAL-ADA4351-2EBZ also provides open resistor and capacitor slots on its input and output stages, allowing users to install components with user-defined values for connections such as a low-pass filter (LPF) or voltage divider. The EVAL-ADA4351-2EBZ is accessible through Subminiature Version A (SMA) female socket edge mounts that allow users to directly connect test equipment to the inputs and outputs of both channels and the gain switch control pins. This evaluation board also has an unpopulated photodiode slot on each channel, allowing quick prototyping.

Features

• Small, dual-channel, complete PGTIA and AFE solution
• Small size package: 16-lead LFCSP, 3 mm × 3 mm
• Integrated switches: 2 external gains per channel
• Wide input current dynamic range from picoamps to milliamps
• Excellent DC precision
• Low offset voltage: ±100 μV maximum, +25°C
• Low offset voltage drift: ±0.85 μV/°C maximum, -40°C to +125°C
• Low input bias current: ±9 pA maximum, +25°C
• Low switch off leakage current: ±90 pA maximum (−40°C to +125°C)
• Integrated architecture eliminates gain error due to switch resistance
• Single-supply operation: +2.7 V to +5.5 V (dual-supply operation: ±1.85 V to ±2.75 V)
• Wide gain bandwidth product: 8.5 MHz
• Wide operating temperature range: -40°C to +125°C