CMOS, High-Speed, 8-Bit ADCs with Multiplexer MAX154/MAX158 MX782

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CMOS, High-Speed, 8-Bit ADCs with Multiplexer MAX154/MAX158 MX782

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19-0255; 4/94
CMOS, High-Speed, 8-Bit ADCs with Multiplexer
MAX154/MAX158 MX7824/MX7828 highspeed, multi-channel analog-to-digital converters (ADCs). MAX154 MX7824 have four analog input channels, while MAX158 MX7828 have eight channels. Conversion time devices 2.5µs. MAX154/MAX158 also feature 2.5V on-chip reference, forming complete high-speed data acquisition system. four converters include built-in track/hold, eliminating need external track/hold with many input signals. analog input range +5V, although operates from single supply. Microprocessor interfaces simplified ADC's ability appear memory location port without need external logic. data outputs latched, three-state buffer circuitry allow direct connection microprocessor data system input port. MX7824 MX7828 compatible with Analog Devices' AD7824 AD7828. MAX154 MAX158, which feature internal references, also compatible with these products.
_Features
One-Chip Data Acquisition System Four Eight Analog Input Channels 2.5µs Channel Conversion Time Internal 2.5V Reference (MAX154/MAX158 only) Built-In Track/Hold Function 1/2LSB Error Specification Single Supply Operation External Clock Space-Saving SSOP Package
MX7824/MX7828
_Ordering Information
PART MX7824LN MX7824KN MX7824LCWG MX7824KCWG MX7824LCAG TEMP. RANGE +70°C +70°C +70°C +70°C +70°C PIN-PACKAGE Narrow Plastic Narrow Plastic Wide Wide SSOP ERROR (LSB) ±1/2 ±1/2 ±1/2
_Applications
Digital Signal Processing High-Speed Data Acquisition Telecommunications High-Speed Servo Control Audio Instrumentation
MX7824KCAG +70°C SSOP Ordering Information continued last page.
_Pin Configurations
VIEW
AIN6 AIN4 AIN3 AIN2 AIN1 (REF OUT) AIN5 AIN4 AIN3 AIN2 AIN1 (REF OUT) AIN7 AIN8
MAX158 MX7828
VREF+ VREF-
MAX154 MX7824
VREF+ VREF-
DIP/SO/SSOP DIP/SO/SSOP
MAX154/MAX158 ONLY.
Maxim Integrated Products
Call toll free 1-800-998-8800 free samples literature.
CMOS, High-Speed, 8-Bit ADCs with Multiplexer MX7824/MX7828
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, .0V, +10V Voltage Other Pins.GND 0.3V, 0.3V Output Current (REF OUT).30mA Power Dissipation (any package) +75°C .450mW Derate above +25°C .6mW/°C Operating Temperature Ranges MX7824, MX7828 KN/LN/KCW_/LCW_ .0°C +70°C BQ/CQ .-40°C +85°C TQ/UQ.-55°C +125°C Storage Temperature Range .-65°C +160°C Lead Temperature (soldering, 10sec) .+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS
(VDD +5V, VREF+ +5V, VREF- GND, Mode TMIN TMAX, unless otherwise noted.) PARAMETER ACCURACY Resolution Total Unadjusted Error (Note Missing Codes Resolution Channel Channel Mismatch REFERENCE INPUT Reference Resistance VREF+ Input Voltage Range VREF- Input Voltage Range REFERENCE OUTPUT-MAX154/MAX158 Only (Note Output Voltage Load Regulation Power-Supply Sensitivity Temperature Drift (Note Output Noise Capacitive Load ANALOG INPUT Analog Input Voltage Range Analog Input Capacitance Analog Input Current AINR CAIN IAIN channel, VREF45 0.157 VREF+ V/µs +25°C 10mA, +25°C ±5%, +25°C MAX15_C MAX15_E MAX15_M 2.47 2.50 0.01 2.53 µV/rms ppm/°C VREFGND VREF+ MAX15_A, MX782_L/C/U MAX15_B, MX782_K/B/T ±1/4 ±1/2 Bits Bits SYMBOL CONDITIONS UNITS
Slew Rate, Tracking LOGIC INPUTS Input High Voltage Input Voltage Input High Current Input Current Input Capacitance (Note VINH VINL IINH IINL
CMOS, High-Speed, 8-Bit ADCs with Multiplexer
ELECTRICAL CHARACTERISTICS
(VDD +5V, VREF+ +5V, VREF- GND, Mode TMIN TMAX, unless otherwise noted.) PARAMETER LOGIC OUTPUTS Output High Voltage Output Voltage Three-State Output Current Output Capacitance (Note POWER SUPPLY Supply Voltage Supply Current Power Dissipation Power-Supply Sensitivity Note Note Note Note specified performance 2.4V 4.75 ±1/16 5.25 ±1/4 COUT DB0-DB7, INT; IOUT -360µA DB0-DB7, INT; IOUT 1.6mA IOUT 2.6mA SYMBOL CONDITIONS UNITS
MX7824/MX7828
DB0-DB7, RDY; VOUT
Total unadjusted error includes offset, full-scale, linearity errors. Specified with external load unless otherwise noted. Temperature drift defined change output voltage from +25°C TMIN TMAX divided TMIN) (TMAX 25). Guaranteed design.
TIMING CHARACTERISTICS (Note
(VDD +5V, VREF+ +5V, VREF- GND, Mode TMIN TMAX, unless otherwise noted.) +25°C Setup Time Hold Time Multiplexer Address Setup Time Multiplexer Address Hold Time Delay Conversion Time (Mode Data Access Time After Data Access Time After INT, Mode Delay (Mode Data Hold Time Delay Time Between Conversions Pulse Width (Mode tCSS tCSH tRDY tCRD tACC1 tACC2 tINTH 50pF, (Note (Note 50pF (Note MAX15_ _C/E MX782_K/L/B/C MAX15_ MX782_T/U
PARAMETER
SYMBOL
CONDITIONS
UNITS
Note input control signals specified with 20ns (10% +5V) timed from 1.6V voltage level. Note Measured with load circuits Figure defined time required output cross 0.8V 2.4V. Note Defined time required data lines change 0.5V when loaded with circuits Figure
CMOS, High-Speed, 8-Bit ADCs with Multiplexer MX7824/MX7828
_Typical Operating Characteristics
+25°C, unless otherwise noted.)
REFERENCE TEMPERATURE DRIFT (MAX154/MAX158 ONLY)
MX7824/28-1
OUTPUT CURRENT TEMPERATURE
OUTPUT CURRENT (mA) ISOURCE VOUT 2.4V
MX7824/28-2
ACCURACY DELAY BETWEEN CONVERSIONS (tp)
VREF
MX7824/28-3
2.520
VOLTAGE
2.510
LINEARITY ERROR (LSB)
2.500
ISINK VOUT 0.4V
2.490
2.480 AMBIENT TEMPERATURE (°C)
-100 AMBIENT TEMPERATURE (°C)
(ns)
ACCURACY VREF (VREF VREF+ VREF-)
MX7824/28-4
POWER-SUPPLY CURRENT TEMPERATURE (NOT INCLUDING REFERENCE LADDER)
MX7824/28-5
LINEARITY ERROR (LSB)
SUPPLY CURRENT (mA) 4.75V 5.25V
VREF
-100
AMBIENT TEMPERATURE (°C)
DGND 100pF 100pF DGND DGND 10pF
10pF DGND
High-Z
High-Z
High-Z
High-Z
Figure Load Circuits Data-Access Time Test
Figure Load Circuits Data-Hold Time Test
CMOS, High-Speed, 8-Bit ADCs with Multiplexer
_Pin Descriptions
NAME MAX154 MX7824 AIN4 AIN3 AIN2 AIN1 Analog Input Channel Analog Input Channel Analog Input Channel Analog Input Channel Reference Output (2.5V) MAX154. Test point MX7824. connect. Three-State Data Output, (LSB) Three-State Data Output, Three-State Data Output, Three-State Data Output, Read Input. controls conversions data access. Digital Interface section. Interrupt Output. going indicates completion conversion. Digital Interface section. Ground Lower Limit Reference Span. Sets zero-code voltage. Range: VREF+. Upper Limit Reference Span. Sets full-scale input voltage. Range: VREF- VDD. Ready Output. Open-drain output with active pull-up device. Goes when goes high impedance conversion. Chip-Select Input. must device selected. Three-State Data Output, Three-State Data Output, Three-State Data Output, Three-State Data Output, (MSB) Channel Address Input Channel Address Input Connect Power-Supply Voltage, AIN8 AIN7 FUNCTION MAX158 MX7828 AIN6 AIN5 AIN4 AIN3 AIN2 AIN1 Analog Input Channel Analog Input Channel Analog Input Channel Analog Input Channel Analog Input Channel Analog Input Channel Reference Output (2.5V) MAX158. Test point MX7828. connect. Three-State Data Output, (LSB) Three-State Data Output, Three-State Data Output, Three-State Data Output, Read Input. controls conversions data access. Digital Interface section. Interrupt Output. going indicates completion conversion. Digital Interface section. Ground Lower Limit Reference Span. Sets zero-code voltage. Range: VREF+. Upper Limit Reference Span. Sets full-scale input voltage. Range: VREF- VDD. Ready Output. Open-drain output with active pull-up device. Goes when goes high impedance conversion. Chip-Select Input. must device selected. Three-State Data Output, Three-State Data Output, Three-State Data Output, Three-State Data Output, (MSB) Channel Address Input Channel Address Input Channel Address Input Power-Supply Voltage, Analog Input Channel Analog Input Channel NAME FUNCTION
MX7824/MX7828
VREF-
VREF-
VREF+
VREF+
CMOS, High-Speed, 8-Bit ADCs with Multiplexer MX7824/MX7828
_Detailed Description
Converter Operation
MAX154/MAX158 MX7824/MX7828 what commonly called "half-flash" conversion technique (Figure 4-bit flash sections used achieve 8-bit result. Using comparators, upper 4-bit (most significant) flash compares unknown input voltage reference ladder provides upper four data bits. internal uses bits generate analog signal from first flash conversion. residue voltage representing difference between unknown input voltage then compared reference ladder (least significant) flash comparators obtain lower four output bits.
_Digital Interface
MAX154/MAX158 MX7824/MX7828 only Chip Select (CS) Read (RD) control inputs. READ operation, taking low, latches multiplexer address inputs starts conversion (Table
Table Truth Table Input Channel Selection
MAX154/MX7824 MAX158/MX7828 SELECTED CHANNEL AIN1 AIN2 AIN3 AIN4 AIN5 AIN6 AIN7 AIN8
Operating Sequence
operating sequence shown Figure conversion initiated falling edge comparator inputs track analog input voltage approximately 1µs. After this first cycle, flash result latched into output buffers conversion begins. goes approximately 600ns later, indicating conversion, that lower four bits latched into output buffers. data then accessed using inputs.
There interface modes, which determined length input. Mode implemented keeping until conversion ends, designed microprocessors that forced into WAIT state. this mode, conversion started with READ operation (taking low), data read when conversion ends. Mode other hand,
VREF+ VREFAIN1
4-BIT FLASH (4MSB)
AIN4
MUX*
4-BIT
THREESTATE DRIVERS
AIN8
VREF+
4-BIT FLASH (4LSB)
OUT**
2.5V
ADDRESS LATCH DECODE
TIMING CONTROL CIRCUITRY
*MAX154/MX7824 4-Channel MAX158/MX7828 8-Channel MAX154/MAX158 only
Figure Functional Diagram
CMOS, High-Speed, 8-Bit ADCs with Multiplexer
500ns 1000ns 600ns GOING INDICATES THAT CONVERSION COMPLETE THAT DATA READ
SETUP TIME REQUIRED INTERNAL COMPARATORS PRIOR STARTING CONVERSION
SAMPLED FOUR MSBs LATCHED
There status outputs: Interrupt (INT) Ready (RDY). RDY, open-drain output internal pull-up device), connected processor's READY/WAIT input. goes falling edge goes high impedance conversion, when conversion result appears data outputs. output required, external pull-up resistor omitted. goes when conversion complete returns high rising edge
MX7824/MX7828
TRACKED INTERNAL COMPARATORS
Interface Mode
Mode designed applications where microprocessor forced into WAIT state. Taking latches multiplexer address starts conversion (Figure Data from previous conversion immediately read from outputs (DB0-DB7). goes high rising edge goes conversion. second READ operation required read result this conversion. second READ latches multiplexer address starts another conversion. delay 2.5µs must allowed between READ operations. goes falling edge goes high impedance rising edge needed, external pull-up resistor omitted.
Figure Operating Sequence
does require microprocessor WAIT states. READ operation simultaneously initiates conversion reads previous conversion result.
Interface Mode
Figure shows timing diagram Mode operation. This used with microprocessors that have WAIT state capability, whereby READ instruction extended accommodate slow-memory devices. Taking latches analog multiplexer address starts conversion. Data outputs DB0-DB7 remain high-impedance condition until conversion complete.
tCSS
tCSH
tCSS
ANALOG CHANNEL ADDRESS tRDY ADDR VALID ADDR VALID
tINTH tCRD tACC2 DATA VALID
DATA
HIGH IMPEDANCE
Figure Mode Timing Diagram
CMOS, High-Speed, 8-Bit ADCs with Multiplexer MX7824/MX7828
tCSS
tCSH
tCSS
tCSH
ANALOG CHANNEL ADDRESS tRDY tCRD tINTH tINTH tRDY ADDR VALID ADDR VALID
tACCI DATA
tACCI DATA
DATA
Figure Mode Timing Diagram
_Analog Considerations
Reference Input
VREF+ VREF- inputs converter define zero full-scale ADC. other words, voltage VREF- equal input voltage that produces output code zeros, voltage VREF+ equal input voltage that produces output code ones (Figure Figure shows some possible reference configurations. MAX154/MAX158, 0.01µF bypass capacitor should used reduce highfrequency output impedance internal reference. Larger capacitors should used, this degrades stability reference buffer. 2.5V reference output with respect pin.
OUTPUT CODE 11111111 11111110 11111101 FULL-SCALE TRANSITION
1LSB VREF+ VREF256 00000011 00000010 00000001 VREF+
Bypassing
47µF electrolytic 0.1µF ceramic capacitor should used bypass GND. These capacitors must have minimum lead length, since excess lead length contribute conversion errors instability. reference inputs driven long lines, they should bypassed with 0.1µF capacitors reference input pins.
00000000 VREF1 INPUT VOLTAGE TERMS LSBs) FS-1LSB
Figure Transfer Function
CMOS, High-Speed, 8-Bit ADCs with Multiplexer
AINx(+) AINx(-) 0.1µF 47µF 0.01µF VREFVREF+
Input Current
converters' analog inputs behave somewhat differently from conventional ADCs. sampled data comparators take varying amounts current from input, depending cycle they equivalent circuit converter shown Figure When conversion starts, AIN(n) connected comparators. Thus, AIN(n) connected thirty-one capacitors. acquire input signal approximately 1µs, input capacitors must charge input voltage through on-resistance multiplexer (about 600) comparator's analog switches comparator). addition, about 12pF stray capacitance must charged. input modeled equivalent network shown Figure (source impedance) increases, capacitors take longer charge. Since length input acquisition time internally set, large source resistances (greater than 100) will cause settling errors. output impedance opamp open-loop output impedance divided loop gain frequency interest. important that amplifier driving converter input have sufficient loop gain approximately 1MHz maintain output impedance.
MX7824/MX7828
MAX154 MAX158
Figure Internal Reference (MAX154/MAX158 only)
AINx(+) AINx(-) 0.1µF 47µF 2.5V
MX584
VREF+ VREF-
MX7824 MX7828
Figure External Reference +2.5V Full-Scale
AINx(+) AINx(-) 0.1µF 47µF
Input Filtering
transients analog input caused sampled data comparators degrade converter's performance, since does "look" input when these transients occur. comparator's outputs track input during first conversion, then latched. Therefore, least will provided charge ADC's input capacitance. necessary filter these transients with external capacitor terminals.
MAX154 MAX158 VREF+ MX7824 MX7828
VREF-
Figure Power Supply Reference
Current path must still exist from VIN(-) Ground 0.1µF 47µF 2.5V AINx(-) VREFAINx(+)
Sinusoidal Inputs
VREF+
MAX154 MAX158 MX7824 MX7828
MAX154/MAX158 MX7824/MX7828 measure input signals with slew rates high 157mV/µs rated specifications. This means that analog input frequency high 10kHz without external track/hold. maximum sampling rate limited conversion time (typical tCRD 2µs) plus time required between conversions 500ns). calculated fMAX 400kHz tCRD (2.0 0.5)
Figure Inputs Referenced
CMOS, High-Speed, 8-Bit ADCs with Multiplexer MX7824/MX7828
fMAX permits maximum sampling rate 50kHz channel when using MAX158/MX7828 100kHz channel when using MAX154/MX7824. These rates well above Nyquist requirement 20kHz sampling rate 10kHz input bandwidth.
3.57k 11.5 10.0k AIN1
Bipolar Input Operation
circuit Figure used bipolar input operation. input voltage scaled amplifier that only positive voltages appear ADC's inputs. external reference should used MX7824/ MX7828, needed with MAX154/MAX158. analog input range output code complementary offset binary. ideal input/output characteristic shown Figure 10b.
0.01µF
16.2k
MAX154 MAX158
0.01µF
VREF+
VREF47µF
DB0-DB7
0.1µF COMPARATORS
AIN1
RMUX
ONLY CHANNEL SHOWN
12pF
LADDER
Figure 10a. Bipolar Input Operation
COMPARATORS
LADDER
11111111 11111110 11111101 10000010 10000001 10000000 01111111 1LSB
1LSB
Figure Equivalent Input Circuit
AIN1
32pF
01111110 00000010 00000001 00000000
INPUT VOLTAGE (LSBs)
Figure Network Model
Figure 10b. Transfer Function Input Operation
CMOS, High-Speed, 8-Bit ADCs with Multiplexer MX7824/MX7828
ADDRESS BANDPASS FILTER ADDRESS DECODE BANDPASS FILTER AIN1 AIN2
MREQ
WAIT D0-D7 DATA
MAX154 MAX158 MX7824 MX7828
DB0-DB7
SPEECH INPUT
MAX158 MX7828
DB0-DB7 BANDPASS FILTER BANDPASS FILTER DATA
AIN7
AIN8 VREF+ VREF15
MAX158/MX7828 ONLY.
Figure Simple Mode Interface
Figure Speech Analysis Using Real-Time Filtering
AIN1 AIN2 AIN3 AIN4 VREF+ VREFGND
SAMPLE PULSE
+15V VREF VOUT
MAX154 MX7824
DB0-DB7
MX7226
DB0-DB7
VOUT VOUT VOUT
DGND AGND
Figure 4-Channel Fast Sample Infinite Hold
CMOS, High-Speed, 8-Bit ADCs with Multiplexer MX7824/MX7828
_Ordering Information (continued)
PART MX7824LEAG MX7824KEAG MX7824CQ MX7824BQ MX7824UQ MX7824TQ MX7828LN MX7828KN MX7828LCWI MX7828KCWI MX7828LCAI MX7828KCAI MX7828LP MX7828KP MX7828LEAI MX7828KEAI MX7828CQ MX7828BQ MX7828UQ MX7828TQ TEMP. RANGE -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -55°C +125°C -55°C +125°C +70°C +70°C +70°C +70°C +70°C +70°C +70°C +70°C -40°C +85°C -40°C +85°C -40°C +85°C -40°C +85°C -55°C +125°C -55°C +125°C PIN-PACKAGE SSOP SSOP CERDIP CERDIP CERDIP CERDIP Plastic Plastic Wide Wide SSOP SSOP PLCC PLCC SSOP SSOP CERDIP CERDIP CERDIP CERDIP ERROR (LSB) ±1/2 ±1/2 ±1/2 ±1/2 ±1/2 ±1/2 ±1/2 ±1/2 ±1/2 ±1/2
VREF+ VREF0.124" (3.150mm) MAX154/MX7824 AIN2 (N.C.) AIN1 (N.C.) (REF OUT) (N.C.) 0.127" (3.228mm)
_Chip Topography
AIN4 AIN6 AIN8 (N.C.) (AIN2) (AIN4) AIN3 AIN5 AIN7 (N.C.) (AIN1) (AIN3)
Maxim cannot assume responsibility circuitry other than circuitry entirely embodied Maxim product. circuit patent licenses implied. Maxim reserves right change circuitry specifications without notice time.
_Maxim Integrated Products, Gabriel Drive, Sunnyvale, 94086 (408) 737-7600 1995 Maxim Integrated Products Printed registered trademark Maxim Integrated Products.

CMOS, High-Speed, 8-Bit ADCs with Multiplexer MAX154/MAX158 MX782

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