2 LC MOS 8-Channel, 12-Bit a High Speed Data Acquisition System AD7891 FEATURES FUNCTIONAL BLOCK DIAGRAM Fast 12-Bit ADC with 1.6 s Conversion Time REF OUT/ V V 8 Single-Ended Analog Input Channels DD DD REF IN REF GND Overvoltage Protection on Each Channel V IN1A Selection of Input Ranges: 2.5V V IN1B REFERENCE 5 V, 10 V for AD7891-1 STANDBY V IN2A AD7891 V 0 to +2.5 V, 0 to +5 V, 2.5 V for AD7891-2 IN2B V IN3A Parallel and Serial Interface V IN3B On-Chip Track/Hold Amplifier V 12-BIT IN4A M ADC V On-Chip Reference IN4B U V X IN5A Single-Supply, Low Power Operation (100 mW Max) V IN5B Power-Down Mode (75 W Typ) TRACK/HOLD V IN6A V IN6B APPLICATIONS DATA/ V ADDRESS IN7A CONTROL V DECODE Data Acquisition Systems IN7B LINES V IN8A Motor Control V IN8B Mobile Communication Base Stations CLOCK CONTROL LOGIC Instrumentation WR CS RD EOC CONVST MODE AGND AGND DGND GENERAL DESCRIPTION PRODUCT HIGHLIGHTS The AD7891 is an 8-channel, 12-bit data acquisition system 1. The AD7891 is a complete monolithic 12-bit data acquisition with a choice of either parallel or serial interface structure. The system that combines an 8-channel multiplexer, 12-bit ADC, part contains an input multiplexer, an on-chip track/hold ampli- 2.5 V reference, and track/hold amplifier on a single chip. fier, a high speed 12-bit ADC, a 2.5 V reference, and a high 2. The AD7891-2 features a conversion time of 1.6 ms and an speed interface. The part operates from a single 5 V supply and acquisition time of 0.4 ms. This allows a sample rate of accepts a variety of analog input ranges across two models, the 500 kSPS when sampling one channel and 62.5 kSPS when AD7891-1 (5V and 10 V) and the AD7891-2 (0 V to +2.5 V, channel hopping. These sample rates can be achieved using 0V to +5 V, and 2.5 V). either a software or hardware convert start. The AD7891-1 The AD7891 provides the option of either a parallel or serial has an acquisition time of 0.6 ms when using a hardware interface structure determined by the MODE pin. The part convert start and an acquisition time of 0.7 ms when using a has standard control inputs and fast data access times for both software convert start. These acquisition times allow sample the serial and parallel interfaces, ensuring easy interfacing to rates of 454.5 kSPS and 435 kSPS, respectively, for hardware modern microprocessors, microcontrollers, and digital signal and software convert start. processors. 3. Each channel on the AD7891 has overvoltage protection. This In addition to the traditional dc accuracy specifications, such as means an overvoltage on an unselected channel does not affect linearity, full-scale and offset errors, the part is also specified for the conversion on a selected channel. The AD7891-1 can dynamic performance parameters, including harmonic distortion withstand overvoltages of 17 V. and signal-to-noise ratio. Power dissipation in normal mode is 82 mW typical in the standby mode, this is reduced to 75 mW typ. The part is available in a 44-terminal MQFP and a 44-lead PLCC. REV. D Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. may result from its use. No license is granted by implication or otherwise Tel: 781/329-4700 www.analog.com under any patent or patent rights of Analog Devices. Trademarks and Fax: 781/326-8703 2004 Analog Devices, Inc. All rights reserved. registered trademarks are the property of their respective owners.(V = 5 V 5%, AGND = DGND = 0 V, REF IN = 2.5 V. All specifications T to T , DD MIN MAX unless otherwise noted.) AD7891SPECIFICATIONS 1 Parameter A Version B Version Y Version Unit Test Conditions/Comments 2 3 DYNAMIC PERFORMANCE Sample Rate = 454.5 kSPS (AD7891-1), 3 500 kSPS (AD7891-2). Any channel. 4 Signal-to-(Noise + Distortion) Ratio 25 C707070dB min T to T 70 70 70 dB min MIN MAX 4 Total Harmonic Distortion 78 78 78 dB max 4 Peak Harmonic or Spurious Noise 80 80 80 dB max 4 Intermodulation Distortion fa = 9 kHz, fb = 9.5 kHz. Second-Order Terms 80 80 80 dB typ Third-Order Terms 80 80 80 dB typ 4 Channel-to-Channel Isolation 80 80 80 dB max DC ACCURACY Any channel. Resolution 12 12 12 Bits Minimum Resolution for which No Missing Codes Are Guaranteed 12 12 12 Bits 4 Relative Accuracy 1 0.75 1 LSB max 4 Differential Nonlinearity 1 1 1 LSB max 4 Positive Full-Scale Error 3 3 3 LSB max 4, 5 Positive Full-Scale Error Match 0.6 0.6 0.6 LSB typ 1.5 LSB max. Unipolar Offset Error 4 4 4 LSB max Input ranges of 0 V to 2.5 V, 0 V to 5 V. 5 Unipolar Offset Error Match 0.1 0.1 0.1 LSB typ 1 LSB max. 4 Negative Full-Scale Error 3 3 3 LSB max Input ranges of 2.5 V, 5V, 10 V. 4, 5 Negative Full-Scale Error Match 0.6 0.6 0.6 LSB typ 1.5 LSB max. Bipolar Zero Error 4 4 4 LSB max Input ranges of 2.5 V, 5V, 10 V. 5 Bipolar Zero Error Match 0.2 0.2 0.2 LSB typ 1.5 LSB max. ANALOG INPUTS AD7891-1 Input Voltage Range 5 5 5V Input applied to both V and V . INXA INXB 10 10 10 V Input applied to V , V = AGND. INXA INXB AD7891-1 V Input Resistance 7.5 7.5 7.5 kW min Input range of 5V. INXA AD7891-1 V Input Resistance 15 15 15 kW min Input range of 10 V. INXA AD7891-2 Input Voltage Range 0 to 2.5 0 to 2.5 0 to 2.5 V Input applied to both V and V . INXA INXB 0 to 5 0 to 5 0 to 5 V Input applied to V , V = AGND. INXA INXB 6 2.5 2.5 2.5 V Input applied to V , V = REF IN . INXA INXB AD7891-2 V Input Resistance 1.5 1.5 1.5 kW min Input ranges of 2.5 V and 0 V to 5 V. INXA AD7891-2 V Input Current 50 50 50 nA max Input range of 0 V to 2.5 V. INXA REFERENCE INPUT/OUTPUT REF IN Input Voltage Range 2.375/2.625 2.375/2.625 2.375/2.625 V min/V max 2.5 V 5%. Input Impedance 1.6 1.6 1.6 kW min Resistor connected to internal reference node. 5 Input Capacitance 10 10 10 pF max REF OUT Output Voltage 2.5 2.5 2.5 V nom REF OUT Error 25 C 10 10 10 mV max T to T 20 20 20 mV max MIN MAX REF OUT Temperature Coefficient 25 25 25 ppm/ C typ REF OUT Output Impedance 5 5 5 kW nom See REF IN input impedance. LOGIC INPUTS Input High Voltage, V 2.4 2.4 2.4 V min V = 5 V 5%. INH DD Input Low Voltage, V 0.8 0.8 0.8 V max V = 5 V 5%. INL DD Input Current, I 10 10 10 mA max INH 5 Input Capacitance C 10 10 10 pF max IN REV. D 2