Document
16-Bit, 100 kSPS PulSAR Differential ADC in MSOP AD7684
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FEATURES
16-bit resolution with no missing codes Throughput: 100 kSPS INL: ±1 LSB typ, ±3 LSB max True differential analog input range: ±VREF 0 V to VREF with VREF up to VDD on both inputs Single-supply operation: 2.7 V to 5.5 V Serial interface SPI-®/QSPI-™/MICROWIRE-™/DSP-compatible Power Dissipation : 4 mW @ 5 V, 1.5 mW @ 2.7 V, 150 µW @ 2.7 V/10 kSPS Standby current: 1 nA 8-lead MSOP package
APPLICATION DIAGRAM
0.5V TO VDD 2.7V TO 5.5V VREF 0 +IN –IN VREF 0 REF VDD DCLOCK 3-WIRE SPI INTERFACE
04302-001
AD7684
GND
DOUT CS
Figure 1.
APPLICATIONS
Battery-powered equipment Data acquisition Instrumentation Medical instruments Process control
Table 1. MSOP, QFN (LFCSP)/SOT-23, 16-Bit PulSAR ADCs
Type True Differential Pseudo Differential/Unipolar Unipolar 100 kSPS AD7684 AD7683 AD7680 250 kSPS AD7687 AD7685 AD7694 500 kSPS AD7688 AD7686
GENERAL DESCRIPTION
The AD7684 is a 16-bit, charge redistribution, successive approximation, PulSAR™ analog-to-digital converter (ADC) that operates from a single power supply, VDD, between 2.7 V to 5.5 V. It contains a low power, high speed, 16-bit sampling ADC with no missing codes, an internal conversion clock, and a serial, SPI-compatible interface port. The part also contains a low noise, wide bandwidth, short aperture delay, track-and-hold circuit. On the CS falling edge, it samples the voltage difference between +IN and –IN pins. The reference voltage, REF, is applied externally and can be set up to the supply voltage. Its power scales linearly with throughput. The AD7684 is housed in an 8-lead MSOP package, with an operating temperature specified from −40°C to +85°C.
Rev. 0
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AD7684 TABLE OF CONTENTS
Specifications..................................................................................... 3 Timing Specifications....................................................................... 5 Absolute Maximum Ratings............................................................ 6 ESD Caution.................................................................................. 6 Pin Configuration and Function Descriptions............................. 7 Terminology ...................................................................................... 8 Typical Performance Characteristics ............................................. 9 Application Information................................................................ 12 Circuit Information.................................................................... 12 Converter Operation.................................................................. 12 Transfer Functions...................................................................... 12
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Typical Connection Diagram ................................................... 13 Analog Input ............................................................................... 13 Driver Amplifier Choice............................................................ 13 Voltage Reference Input ............................................................ 14 Power Supply............................................................................... 14 Digital Interface.......................................................................... 14 Layout .......................................................................................... 14 Evaluating the AD7684’s Performance .................................... 14 Outline Dimensions ....................................................................... 15 Ordering Guide .......................................................................... 15
REVISION HISTORY
10/04—Initial Version: Revision 0
Rev. 0 | Page 2 of 16
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AD7684
SPECIFICATIONS
VDD = 2.7 V to 5.5 V; VREF = VDD; TA = –40°C to +85°C, unless otherwise noted. Table 2.
Parameter RESOLUTION ANALOG INPUT Voltage Range Absolute Input Voltage Analog Input CMRR Leakage Current at 25°C Input Impedance THROUGHPUT SPEED Complete Cycle Throughput Rate DCLOCK Frequency REFERENCE Voltage Range Load Current DIGITAL INPUTS Logic Levels VIL VIH IIL IIH Input Capacitance DIGITAL OUTPUTS Data Format VOH VOL POWER SUPPLIES VDD VDD Range1 Operating Current Conditions Min 16 −VREF −0.1 Typ Max Unit Bits V V dB nA
+IN − (–IN) +IN, –IN fI.