14-Bit, 1 MSPS SAR ADC

The AD7485 is a 14-bit, high speed, low power, successive-approximation ADC. The part features a serial interface with throughput rates up to 1 MSPS. The part contains a low-noise, wide bandwidth track/hold amplifier, which can handle input frequencies in excess of 10MHz.

The conversion process is a proprietary algorithmic successive-approximation technique. The input signal is sampled and conversion is initiated on the falling edge of a CONVST signal. The conversion process is controlled by an external master clock. Interfacing is via standard serial signal lines making the part directly compatible with microcontrollers and DSPs.

The AD7485 provides excellent ac and dc performance specifications. Factory trimming ensures high dc accuracy resulting in very low INL, offset and gain errors.

The part uses advanced design techniques to achieve very low power dissipation at high throughput rates. Power consumption in normal mode of operation is 70 mW. There are two power-saving modes: a NAP mode, which keeps reference circuitry alive for quick power up, consumes 5 mW while a STANDBY mode reduces power consumption to a mere 5 µW.

The AD7485 features an on-board 2.5 V reference, but the part can also accommodate an externally provided 2.5 V reference source. The nominal analog input range is 0 V to 2.5 V.

The AD7485 also provides the user with overrange indication via a fifteenth bit. If the analog input range strays outside the 0 V to 2.5 V input range, the fifteenth data bit is set to a logic high.

The AD7485 is powered from a 4.75 V to 5.25 V supply. The part also provides a VDRIVE pin that allows the user to set the voltage levels for the digital interface lines. The range for this VDRIVE pin is from 2.7 V to 5.25 V. The part is housed in a 48-lead LQFP package and is specified over a –40°C to +85°C temperature range.

* Fast Throughput Rate: 1 MSPS

* Wide Input Bandwidth: 40 MHz

* Excellent DC Accuracy Performance

* Flexible Serial Interface