- Integrated bipolar charge pump
- Simplified isolation requirements
- Wide input range on low voltage supplies
- Dedicated output amplifier supplies for ADC protection
- Low power: 83 mW (DVDD = 3 V, VDDCP = 5 V)
- 36 precision gains from 1/16 V/V to 176 V/V
- Robust ±60 V protected 2:1 input multiplexer
- Low input bias current: ±1.5 nA maximum at TA = 25°C
- Integrated input EMI filtering
- 7 GPIOx ports with special functions
- Sequential chip select mode
- Excellent dc precision
- Low input offset voltage: ±14 µV maximum
- Low input offset voltage drift: ±0.08 µV/°C maximum
- Gain calibration via internal memory
- Low gain drift: ±1 ppm/°C maximum
- High CMRR: 111 dB minimum, G = 1 V/V
- Excitation current source
- SPI port with checksum (CRC) support
- Internal/external fault detection
- Compact 28-lead, 5 mm × 5 mm LFCSP
- Specified temperature range: −40°C to +105°C
The ADA4255 is a precision programmable gain instrumentation amplifier (PGIA) with integrated bipolar charge pumps. With its integrated charge pumps, the ADA4255 internally produces the high voltage bipolar supplies needed to achieve a wide input voltage range (38 V typical with VDDCP = 5 V) without lowering input impedance. The charge pump topology of the ADA4255 allows channels to be isolated with only low voltage components, reducing complexity, size, and implementation time in industrial and process control systems.
The zero drift PGIA topology of the ADA4255 self calibrates dc errors and lower frequency 1/f noise, achieving excellent dc precision over the entire specified temperature range. The combination of 36 precision gains ranging from 1/16 V/V to 176 V/V within the ADA4255 and high voltage, high impedance inputs allow a wide range of inputs to be scaled to the range of the analog-to-digital converter (ADC). By integrating all gain setting and level shifting resistors, the ADA4255 achieves excellent common-mode rejection ratio (CMRR) performance (111 dB minimum at G = 1 V/V) and extremely low gain drift (±1 ppm/°C maximum). This high level of precision maximizes dynamic range and greatly reduces calibration requirements in many applications.
The ±60 V input protection, integrated electromagnetic interference (EMI) filtering and various safety features make the ADA4255 an ideal choice for robust industrial systems. Seven general-purpose input and output (GPIOx) pins, which can be configured to provide various special functions, are included in the ADA4255. An excitation current source output is available to bias sensors such as resistance temperature detectors (RTDs).
The ADA4255 is specified over the −40°C to +105°C temperature range and is offered in a compact 5 mm × 5 mm, 28-lead LFCSP.
- Universal process control front ends
- Data acquisition systems
- Test and measurement systems
- System power monitoring
The ADA4255CP-EBZ evaluation board is designed to help users evaluate the ADA4255 in its 28-lead lead frame chip scale package (LFCSP). Figure 1 and Figure 2 in the user guide show the front side and back side of the ADP4255CP-EBZ evaluation board with the 28-lead LFCSP.
The ADA4255CP-EBZ is a 4-layer printed circuit board (PCB). This evaluation board accepts Subminiature Version A (SMA) edge-mounted connectors on the inputs and outputs to efficiently connect to test equipment and/or other circuitry.
The ADA4255CP-EBZ requires the following three supply domains:
- A charge pump voltage, VDDCP, of typically 5 V that generates the high voltage supply domain, which includes VDDH and VSSH, and that are typically +22.3 V and −21.7 V, respectively.
- An analog supply domain, AVDD, of typically 5 V.
- A digital supply domain, DVDD, of typically 3.3 V.