AD7891

Features:

Fast 12-Bit ADC with 1.6 ms Conversion Time
Eight Single-Ended Analog Input Channels
Overvoltage Protection on Each Channel
Selection of Input Ranges:
65 V, 610 V for AD7891-1
0 to +2.5 V, 0 to +5 V, 62.5 V for AD7891-2
Parallel and Serial Interface
On-Chip Track/Hold Amplifier
On-Chip Reference
Single Supply, Low Power Operation (85 mW max)
Power-Down Mode (75 mW typ)




Application

Data Acquisition Systems
Motor Control
Mobile Communication Base Stations
Instrumentation




Pinout








Specifications

(TA = +25°C unless otherwise noted)
VDD to AGND . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +7 V
VDD to DGND . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +7ÊV
Analog Input Voltage to AGND
AD7891-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±17ÊV
AD7891-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 V, +10ÊV
Reference Input Voltage to AGND . . . . 0.3 V to VDD + 0.3ÊV
Digital Input Voltage to DGND . . . . . . 0.3 V to VDD + 0.3 V
Digital Output Voltage to DGND . . . . . 0.3 V to VDD + 0.3 V
Operating Temperature Range
Commercial (A, B Version) . . . . . . . . . . . . 40°C to +85°C
Automotive (Y Version) . . . . . . . . . . . . . . 55°C to +105°C
Storage Temperature Range . . . . . . . . . . . . 65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . +150°C
PQFP Package, Power Dissipation . . . . . . . . . . . . . . 450 mW
qJA Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . 95°C/W
Lead Temperature, Soldering
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . +215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C
PLCC Package, Power Dissipation . . . . . . . . . . . . . . 500 mW
qJA Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . 55°C/W
Lead Temperature, Soldering
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . +215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C






Description

The AD7891 is an eight-channel 12-bit data acquisition system with a choice of either parallel or serial interface structure. The part contains an input multiplexer, an on-chip track/hold amplifier,a high speed 12-bit ADC, a +2.5ÊV reference and a high speed interface. The part operates from a single +5 V supply and accepts a variety of analog input ranges across two models,the AD7891-1 (±5ÊV and ±10ÊV) and the AD7891-2 (0 V to +2.5 V, 0 V to +5ÊV and ±2.5ÊV).
The AD7891 provides the option of either a parallel interface or serial interface structure determined by the MODE pin. The part has standard control inputs and fast data access times for both the serial and parallel interfaces which ensures easy interfacing to modern microprocessors, microcontrollers and digital signal processors.
In addition to the traditional dc accuracy specifications such as linearity, full-scale and offset errors, the part is also specified for dynamic performance parameters including harmonic distortion and signal-to-noise ratio.
Power dissipation in normal mode is 90 mW typical while in the standby mode this is reduced to 75 mW typ. The part is available in a 44-terminal plastic quad flatpack (PQFP) and a 44-lead plastic leaded chip carrier (PLCC).