Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsData collecting ICsData acquisition IC - ADC 12 Bit PDIP 24

General Description

The MAX1270/MAX1271 are multirange, 12-bit data-

acquisition systems (DAS) that require only a single

+5V supply for operation, yet accept signals at their

analog inputs that can span above the power-supply

rail and below ground. These systems provide eight

analog input channels that are independently software

programmable for a variety of ranges: ±10V, ±5V, 0 to

+10V, 0 to +5V for the MAX1270; ±V

REF

, ±V

REF

/2, 0 to

REF

, 0 to V

REF

/2 for the MAX1271. This range switch-

ing increases the effective dynamic range to 14 bits and

provides the flexibility to interface 4–20mA, ±12V, and

±15V powered sensors directly to a single +5V system.

In addition, these converters are fault protected to

±16.5V; a fault condition on any channel will not affect

the conversion result of the selected channel. Other fea-

tures include a 5MHz bandwidth track/hold, software-

selectable internal/external clock, 110ksps throughput

rate, and internal 4.096V or external reference operation.

The MAX1270/MAX1271 serial interface directly

connects to SPI™/QSPI™ and MICROWIRE™ devices

without external logic.

A hardware shutdown input (SHDN) and two software-

programmable power-down modes, standby (STBYPD)

or full power-down (FULLPD), are provided for low-cur-

rent shutdown between conversions. In standby mode,

the reference buffer remains active, eliminating startup

delays.

The MAX1270/MAX1271 are available in 24-pin narrow

PDIP or space-saving 28-pin SSOP packages.

Applications

Features

♦ 12-Bit Resolution, 0.5 LSB Linearity

♦ +5V Single-Supply Operation

♦ SPI/QSPI and MICROWIRE-Compatible

3-Wire Interface

♦ Four Software-Selectable Input Ranges

MAX1270: 0 to +10V, 0 to +5V, ±10V, ±5V

MAX1271: 0 to V

REF

, 0 to V

REF

/2, ±V

REF

±V

REF

♦ Eight Analog Input Channels

♦ 110ksps Sampling Rate

♦ ±16.5V Overvoltage-Tolerant Input Multiplexer

♦ Internal 4.096V or External Reference

♦ Two Power-Down Modes

♦ Internal or External Clock

♦ 24-Pin Narrow PDIP or 28-Pin SSOP Packages

MAX1270/MAX1271

Multirange, +5V, 8-Channel,

Serial 12-Bit ADCs

________________________________________________________________ Maxim Integrated Products 1

CH0

CH1

CH2

CH3

CH4

CH5

CH6

CH7

DGND



4.7µF

0.1µF

0.01µF

SHDN

MAX1270

MAX1271

+5V

ANALOG

INPUTS

SCLK

DIN

DOUT

SSTRB

I/O

SCK

MOSI

MISO

REF

REFADJ

AGND

MC68HCXX

Typical Operating Circuit

PART

TEMP RANGE

PIN-PACKAGE

INL

(LSB)

MAX1270ACNG

0°C to +70°C 24 Narrow PDIP

±0.5

MAX1270BCNG

0°C to +70°C 24 Narrow PDIP

±1

MAX1270ACAI

0°C to +70°C

28 SSOP

±0.5

MAX1270BCAI

0°C to +70°C

28 SSOP ±1

Ordering Information

19-4782; Rev 2; 9/04

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Pin Configurations appear at end of data sheet.

SPI and QSPI are trademarks of Motorola, Inc.

MICROWIRE is a trademark of National Semiconductor Corp.

Ordering Information continued at end of data sheet.

EVALUATION KIT

AVAILABLE

Industrial Control Systems

Data-Acquisition Systems

Battery-Powered

Instruments

Automatic Testing

Robotics

Medical Instruments

Summary of content (20 pages)

PAGE 1
9-4782; Rev 2; 9/04 KIT ATION EVALU E L B A IL AVA Multirange, +5V, 8-Channel, Serial 12-Bit ADCs Features The MAX1270/MAX1271 are multirange, 12-bit dataacquisition systems (DAS) that require only a single +5V supply for operation, yet accept signals at their analog inputs that can span above the power-supply rail and below ground.
PAGE 2
MAX1270/MAX1271 Multirange, +5V, 8-Channel, Serial 12-Bit ADCs ABSOLUTE MAXIMUM RATINGS VDD to AGND............................................................-0.3V to +6V AGND to DGND.....................................................-0.3V to +0.3V CH0–CH7 to AGND ......................................................... ±16.5V REF, REFADJ to AGND ..............................-0.3V to (VDD + 0.3V) SSTRB, DOUT to DGND.............................-0.3V to (VDD + 0.3V) SHDN, CS, DIN, SCLK to DGND.........
PAGE 3
Multirange, +5V, 8-Channel, Serial 12-Bit ADCs (VDD = +5.0V ±5%; unipolar/bipolar range; external reference mode, VREF = +4.096V; 4.7µF at REF; external clock; fCLK = 2.0MHz, 50% duty cycle (MAX127_B); fCLK = 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, TA = TMIN to TMAX, unless otherwise noted. Typical values are TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ANALOG INPUT Track/Hold Acquisition Time tACQ Small-Signal Bandwidth MAX127_A, fCLK = 1.8MHz 3.
PAGE 4
MAX1270/MAX1271 Multirange, +5V, 8-Channel, Serial 12-Bit ADCs ELECTRICAL CHARACTERISTICS (continued) (VDD = +5.0V ±5%; unipolar/bipolar range; external reference mode, VREF = +4.096V; 4.7µF at REF; external clock; fCLK = 2.0MHz, 50% duty cycle (MAX127_B); fCLK = 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, TA = TMIN to TMAX, unless otherwise noted. Typical values are TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 4.076 4.096 4.
PAGE 5
Multirange, +5V, 8-Channel, Serial 12-Bit ADCs (VDD = +5.0V ±5%; unipolar/bipolar range; external reference mode, VREF = +4.096V; 4.7µF at REF; external clock; fCLK = 2.0MHz, 50% duty cycle (MAX127_B); fCLK = 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, TA = TMIN to TMAX, unless otherwise noted. Typical values are TA = +25°C.) PARAMETER SYMBOL Conversion Time tCONV CONDITIONS External clock mode (Note 8) MAX127_A 6.6 MAX127_B 6.
PAGE 6
MAX1270/MAX1271 Multirange, +5V, 8-Channel, Serial 12-Bit ADCs TIMING CHARACTERISTICS (VDD = +4.75V to +5.25V; unipolar/bipolar range; external reference mode, V REF = +4.096V; 4.7µF at REF; external clock; fCLK = 2.0MHz (MAX127_B); fCLK = 1.8MHz (MAX127_A); TA = TMIN to TMAX, unless otherwise noted. Typical values are TA = +25°C.
PAGE 7
Multirange, +5V, 8-Channel, Serial 12-Bit ADCs 5.5 0 1 2 3 4 5 6 450 350 250 EXTERNAL REFERENCE 50 -40 7 MAX1270/1 toc03 INTERNAL REFERENCE 550 150 0 -15 10 35 60 85 -40 -15 10 35 60 85 TEMPERATURE (°C) FULL POWER-DOWN SUPPLY CURRENT vs. TEMPERATURE NORMALIZED REFERENCE VOLTAGE vs. TEMPERATURE CHANNEL-TO-CHANNEL OFFSET-ERROR MATCHING vs. TEMPERATURE EXTERNAL REFERENCE 110 90 INTERNAL REFERENCE 70 MAX1270/1 toc05 130 1.001 NORMALIZED REFERENCE VOLTAGE 150 1.000 0.
PAGE 8
Typical Operating Characteristics (continued) (Typical Operating Circuit, VDD = +5V; external reference mode, VREF = +4.096V; 4.7µF at REF; external clock, fCLK = 2MHz; 110ksps; TA = +25°C, unless otherwise noted.) VDD = 5V, INTERNAL REFERENCE, fCLK = 2MHz EXTERNAL CLOCK MODE. LOW-RANGE UNIPOLAR MODE. VCH_ = 0 7 6 5 4 3 2 8 AVERAGE SUPPLY CURRENT (mA) MAX1270-toc10 8 MAX1270-toc11 AVERAGE SUPPLY CURRENT vs. CONVERSION RATE (USING FULLPD) AVERAGE SUPPLY CURRENT vs.
PAGE 9
Multirange, +5V, 8-Channel, Serial 12-Bit ADCs 5mA DOUT OR SSTRB +5V MAX1270 MAX1271 510kΩ 100kΩ REFADJ DOUT OR SSTRB CLOAD 0.5mA CLOAD 0.01µF 24kΩ a) HIGH IMPEDANCE TO VOH, VOL TO VOH AND VOH TO HIGH IMPEDANCE Figure 1. Reference-Adjust Circuit b) HIGH IMPEDANCE TO VOH, VOL TO VOH AND VOH TO HIGH IMPEDANCE Figure 2.
PAGE 10
MAX1270/MAX1271 Multirange, +5V, 8-Channel, Serial 12-Bit ADCs Input Bandwidth Digital Interface The ADC’s input small-signal bandwidth depends on the selected input range and varies from 1.5MHz to 5MHz (see Electrical Characteristics). The MAX1270B/ MAX1271B maximum sampling rate is 110ksps (100ksps for the MAX1270A/MAX1271A). By using undersampling techniques, it is possible to digitize high-speed transient events and measure periodic signals with bandwidths exceeding the ADC’s sampling rate.
PAGE 11
Multirange, +5V, 8-Channel, Serial 12-Bit ADCs BIT 7 (MSB) BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 (LSB) START SEL2 SEL1 SEL0 RNG BIP PD1 PD0 BIT NAME 7 (MSB) START DESCRIPTION 6, 5, 4 SEL2, SEL1, SEL0 3 RNG 2 BIP 1, 0 (LSB) PD1, PD0 First logic 1 after CS goes low defines the beginning of the control byte. These 3 bits select the desired “on” channel (Table 2). Selects the full-scale input voltage range (Table 3). Selects the unipolar or bipolar conversion mode (Table 3).
PAGE 12
MAX1270/MAX1271 Multirange, +5V, 8-Channel, Serial 12-Bit ADCs Input Data Format Input data (control byte) is clocked in at DIN at the rising edge of SCLK. CS enables communication with the MAX1270/MAX1271. After CS falls, the first arriving logic 1 bit represents the start bit (MSB) of the input control byte. The start bit is defined as: The first high bit clocked into DIN with CS low anytime the converter is idle; e.g., after VDD is applied.
PAGE 13
Multirange, +5V, 8-Channel, Serial 12-Bit ADCs MAX1270/MAX1271 CS tSTR tSDV SSTRB HIGH-Z HIGH-Z tSSTRB tSSTRB SCLK SCLK 12 Figure 7.
PAGE 14
MAX1270/MAX1271 Multirange, +5V, 8-Channel, Serial 12-Bit ADCs CS SCLK 1 START SEL2 SEL1 SEL0 RNG DIN 9 8 MSB BIP PD1 10 19 D11 D10 D1 20 PD0 LSB SSTRB 16 INT CLK DOUT HIGH-Z HIGH-Z MSB D0 HIGH-Z FILLED WITH ZEROS LSB ACQUISITION CONVERSION A/D STATE 2 EXT SCLK +4 INT CLK 12 INT CLK Figure 9. Internal Clock Mode—20 SCLK/Conversion Timing CS tCSS tSCK tCSH SSTRB tSSTRB SCLK SCLK #8 NOTE: FOR BEST NOISE PERFORMANCE, KEEP SCLK LOW DURING CONVERSION. Figure 10.
PAGE 15
Multirange, +5V, 8-Channel, Serial 12-Bit ADCs MAX1270/MAX1271 CS DIN 8 1 SCLK 9 14 22 16 24 CONTROL BYTE Ø CONTROL BYTE 1 CONTROL BYTE 2 START SEL2 SEL1 SEL0 RNG BIP PD1 PD0 START SEL2 SEL1 SEL0 RNG BIP PD1 PD0 START SEL2 SEL1 SEL0 13 SCLK SSTRB RESULT 1 RESULT Ø HIGH-Z DOUT D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D11 D10 D9 D1 D0 D8 D7 D6 D5 D4 D3 13 SCLK ACQUISITION CONVERSION ACQUISITION CONVERSION A/D STATE Figure 11.
PAGE 16
MAX1270/MAX1271 Multirange, +5V, 8-Channel, Serial 12-Bit ADCs Power-Down Mode REF 4.7µF CREF MAX1270 MAX1271 AV = 1.638 REFADJ 0.01µF 10kΩ 2.5V Figure 13a. Internal Reference REF MAX1270 MAX1271 AV = 1.638 4.096V 4.7µF CREF For hardware-controlled power-down (FULLPD), pull SHDN low. When hardware shutdown is asserted, it becomes effective immediately, and any conversion in progress is aborted.
PAGE 17
Multirange, +5V, 8-Channel, Serial 12-Bit ADCs FULL-SCALE TRANSITION 11... 111 1 LSB = FS 4096 11... 110 OUTPUT CODE 1 LSB = 011... 111 2|FS| 4096 011... 110 11... 101 000... 001 000... 000 111... 111 00... 011 100... 010 00... 010 100... 001 00... 001 100... 000 00... 000 0 1 2 FS 3 INPUT VOLTAGE (LSB) -FS 0 FS - 3/2 LSB Figure 14a. Unipolar Transfer Function +FS - 1 LSB INPUT VOLTAGE (LSB) Figure 14b.
PAGE 18
MAX1270/MAX1271 Multirange, +5V, 8-Channel, Serial 12-Bit ADCs Pin Configurations TOP VIEW VDD 1 28 N.C. VDD 1 24 N.C. DGND 2 27 REF DGND 2 23 REF DGND 3 26 REFADJ N.C. 3 22 N.C. N.C. 4 21 REFADJ DGND 4 MAX1270 MAX1271 SCLK 5 25 N.C. SCLK 5 24 N.C. MAX1270 MAX1271 20 CH7 CS 6 CS 6 19 CH6 N.C. 7 22 N.C. DIN 7 18 CH5 N.C. 8 21 CH6 SSTRB 8 17 CH4 DIN 9 20 CH5 N.C. 9 16 CH3 SSTRB 10 19 CH4 23 CH7 DOUT 10 15 CH2 N.C.
PAGE 19
Multirange, +5V, 8-Channel, Serial 12-Bit ADCs PDIPN.EPS ______________________________________________________________________________________ 19 MAX1270/MAX1271 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.
PAGE 20
Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) 2 SSOP.EPS MAX1270/MAX1271 Multirange, +5V, 8-Channel, Serial 12-Bit ADCs 1 INCHES E H MILLIMETERS DIM MIN MAX MIN MAX A 0.068 0.078 1.73 1.99 A1 0.002 0.008 0.05 0.21 B 0.010 0.015 0.25 0.38 C D 0.20 0.09 0.004 0.008 SEE VARIATIONS E 0.205 e 0.212 0.0256 BSC 5.