Datasheet AD625 (Analog Devices)

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Programmable Gain Instrumentation Amplifier AD625 FEATURES FUNCTIONAL BLOCK DIAGRAM User Programmed Gains of 1 to 10,000 Low Gain Error: 0.02% Max Low Gain TC: 5 ppm/ C Max 50 AD625 –INPUT – – + + Low Nonlinearity: 0.001% Max Low Offset Voltage: 25 V –GAIN 10k SENSE SENSE Low Noise 4 nV/
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Hz (at 1 kHz) RTI –GAIN Gain Bandwidth Product: 25 MHz 10k DRIVE – 16-Lead Ceramic or Plastic DIP Package, VB 10k OUTPUT + 20-Terminal LCC Package +GAIN DRIVE 10k Standard Military Drawing Available +GAIN REFERENCE MlL-Standard Parts Available SENSE 50 + + Low Cost – – +INPUT PRODUCT DESCRIPTION PRODUCT HIGHLIGHTS
The AD625 is a precision instrumentation amplifier specifically 1. The AD625 affords up to 16-bit precision for user selected designed to fulfill two major areas of application: 1) Circuits re- fixed gains from 1 to 10,000. Any gain in this range can be quiring nonstandard gains (i.e., gains not easily achievable with programmed by 3 external resistors. devices such as the AD524 and AD624). 2) Circuits requiring a 2. A 12-bit software programmable gain amplifier can be config- low cost, precision software programmable gain amplifier. ured using the AD625, a CMOS multiplexer and a resistor For low noise, high CMRR, and low drift the AD625JN is the network. Unlike previous instrumentation amplifier designs, most cost effective instrumentation amplifier solution available. the ON resistance of a CMOS switch does not affect the gain An additional three resistors allow the user to set any gain from accuracy. 1 to 10,000. The error contribution of the AD625JN is less than 3. The gain accuracy and gain temperature coefficient of the 0.05% gain error and under 5 ppm/°C gain TC; performance amplifier circuit are primarily dependent on the user selected limitations are primarily determined by the external resistors. external resistors. Common-mode rejection is independent of the feedback resistor matching. 4. The AD625 provides totally independent input and output offset nulling terminals for high precision applications. This A software programmable gain amplifier (SPGA) can be config- minimizes the effects of offset voltage in gain-ranging ured with the addition of a CMOS multiplexer (or other switch applications. network), and a suitable resistor network. Because the ON resistance of the switches is removed from the signal path, an 5. The proprietary design of the AD625 provides input voltage AD625 based SPGA will deliver 12-bit precision, and can be noise of 4 nV/√Hz at 1 kHz. programmed for any set of gains between 1 and 10,000, with 6. External resistor matching is not required to maintain high completely user selected gain steps. common-mode rejection. For the highest precision the AD625C offers an input offset voltage drift of less than 0.25 µV/°C, output offset drift below 15 µV/°C, and a maximum nonlinearity of 0.001%

at G = 1. All grades exhibit excellent ac performance; a 25 MHz gain band- width product, 5 V/µs slew rate and 15 µs settling time. The AD625 is available in three accuracy grades (A, B, C) for industrial (–40°C to +85°C) temperature range, two grades (J, K) for commercial (0°C to +70°C) temperature range, and one (S) grade rated over the extended (–55°C to +125°C) tempera- ture range. REV. D Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its
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