Datasheet

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LTC1091/LTC1092

LTC1093/LTC1094

1-, 2-, 6- and 8-Channel, 10-Bit

Serial I/O Data Acquisition Systems

■

Programmable Features

– Unipolar/Bipolar Conversions

–

Differential/Single-Ended Multiplexer

Configurations

■

Sample-and-Holds

■

Single Supply 5V, 10V or ±5V Operation

■

Direct 3- or 4-Wire Interface to Most MPU Serial

Ports and All MPU Parallel I/O Ports

■

Analog Inputs Common Mode to Supply Rails

■

Resolution: 10 Bits

■

Total Unadjusted Error (A Grade): ±1LSB Over Temp

■

Fast Conversion Time: 20µs

■

Low Supply Current

LTC1091: 3.5mA Max, 1.5mA Typ

LTC1092/LTC1093/LTC1094: 2.5mA Max, 1mA Typ

ANALOG INPUT #1

0V TO 5V RANGE

ANALOG INPUT #2

0V TO 5V RANGE

CLK

OUT

CH0

CH1

GND

LTC1091

MPU

(e.g., 8051)

P1.4

P1.3

P1.2

1091 TA01

SERIAL DATA LINK

FOR 8051 CODE SEE

APPLICATIONS INFORMATION

SECTION

REF

)

4.7µF

REFERENCE VOLTAGE (V)

LINEARITY ERROR (LSB = • V

REF

)

1.25

1.00

0.75

0.50

0.25

1091 TA02

1024

= 5V

The LTC

1091/LTC1092/LTC1093/LTC1094 10-bit data

acquisition systems are designed to provide complete

function, excellent accuracy and ease of use when digitiz-

ing analog data from a wide variety of signal sources and

transducers. Built around a 10-bit, switched capacitor,

successive approximation A/D core, these devices include

software configurable analog multiplexers and bipolar and

unipolar conversion modes as well as on-chip sample-

and-holds. On-chip serial ports allow efficient data trans-

fer to a wide range of microprocessors and microcontrol-

lers. These circuits can provide a complete data acquisi-

tion system in ratiometric applications or can be used with

an external reference in others.

The high impedance analog inputs and the ability to

operate with reduced spans (below 1V full scale) allow

direct connection to sensors and transducers in many

applications, eliminating the need for gain stages.

An efficient serial port communicates without external

hardware to most MPU serial ports and all MPU parallel

I/O ports allowing eight channels of data to be transmitted

over as few as three wires. This, coupled with low power

consumption, makes remote location possible and facili-

tates transmitting data through isolation barriers.

Temperature drift of offset, linearity and full-scale error

are all extremely low (1ppm/°C typically) allowing all

grades to be specified with offset and linearity errors of

±0.5LSB maximum over temperature. In addition, the A

grade devices are specified with full-scale error and total

unadjusted error (including the effects of offset, linearity

and full-scale errors) of ±1LSB maximum over tempera-

ture. The lower grade has a full-scale specification of

±2LSB for applications where full scale is adjustable or

less critical.

, LTC and LT are registered trademarks of Linear Technology Corporation.

FEATURES

DESCRIPTIO

TYPICAL APPLICATION

Summary of content (32 pages)

PAGE 1
LTC1091/LTC1092 LTC1093/LTC1094 1-, 2-, 6- and 8-Channel, 10-Bit Serial I/O Data Acquisition Systems FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ Programmable Features – Unipolar/Bipolar Conversions – Differential/Single-Ended Multiplexer Configurations Sample-and-Holds Single Supply 5V, 10V or ±5V Operation Direct 3- or 4-Wire Interface to Most MPU Serial Ports and All MPU Parallel I/O Ports Analog Inputs Common Mode to Supply Rails Resolution: 10 Bits Total Unadjusted Error (A Grade): ±1LSB Over Temp Fast Conversion Tim
PAGE 2
LTC1091/LTC1092 LTC1093/LTC1094 W W W AXI U U ABSOLUTE RATI GS (Notes 1, 2) Supply Voltage (VCC) to GND or V – ........................ 12V Negative Supply Voltage (V –) .................... – 6V to GND Voltage Analog Reference and LTC1091/2 CS Inputs ................................. (V –) – 0.3V to (VCC + 0.3V) Digital Inputs (except LTC1091/2 CS) .. – 0.3V to 12V Digital Outputs ........................ – 0.3V to (VCC + 0.3V) Power Dissipation .............................................
PAGE 3
LTC1091/LTC1092 LTC1093/LTC1094 U U U U WW RECO E DED OPERATI G CO DITIO S SYMBOL PARAMETER LTC1091A/LTC1092A/LTC1093A/LTC1094A LTC1091/LTC1092/LTC1093/LTC1094 MIN MAX CONDITIONS VCC Supply Voltage V– Negative Supply Voltage LTC1093/LTC1094, VCC = 5V fCLK Clock Frequency tCYC Total Cycle Time UNITS 4.5 10 V – 5.5 0 V VCC = 5V 0.01 0.
PAGE 4
LTC1091/LTC1092 LTC1093/LTC1094 AC CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C.
PAGE 5
LTC1091/LTC1092 LTC1093/LTC1094 U W TYPICAL PERFOR A CE CHARACTERISTICS Change in Linearity Error vs Temperature Change in Offset Error vs Temperature VCC (VREF) = 5V fCLK = 500kHz 0.5 0.4 0.3 0.2 0.1 0 –50 –25 25 50 75 100 0 AMBIENT TEMPERATURE (°C) VCC (VREF) = 5V fCLK = 500kHz 0.5 0.4 0.3 0.2 0.1 0 –50 125 MAGNITUDE OF FULL-SCALE CHANGE (LSB) 0.6 MAGNITUDE OF LINEARITY CHANGE (LSB) MAGNITUDE OF OFFSET CHANGE (LSB) 0.
PAGE 6
LTC1091/LTC1092 LTC1093/LTC1094 U W TYPICAL PERFOR A CE CHARACTERISTICS LTC1091/LTC1092/LTC1093/LTC1094 Maximum Clock Rate vs Source Resistance LTC1091/LTC1092/LTC1093/LTC1094 Maximum Filter Resistor vs Cycle Time 0.75 0.50 0.25 0 “+” OR “–” INPUT 100 1k RSOURCE (Ω) 10 + CFILTER ≥1µF 10k – 1k 100 10 10k 100 1000 CYCLE TIME (µs) 10 1 • VCC (VREF)] 1024 80 60 40 20 1.00 0.75 0.5 0.25 0 125 4 0.25 4 5 6 7 8 SUPPLY VOLTAGE (V) –0.50 5 4 3 2 10 1.4 1.2 1.0 0.
PAGE 7
LTC1091/LTC1092 LTC1093/LTC1094 U W LTC1092/LTC1093/LTC1094 Unadjusted Offset Error vs Reference Voltage LTC1092/LTC1093/LTC1094 Linearity Error vs Reference Voltage 1.25 VCC = 5V 9 LINEARITY ERROR (LSB = 1 • VREF) 1024 OFFSET ERROR (LSB = 1 • VREF) 1024 10 8 7 6 5 4 VOS = 1mV 3 2 1 0 0.1 VOS = 0.5mV 0.2 1 REFERENCE VOLTAGE (V) VCC = 5V 1.00 0.75 0.50 0.25 0 5 10 1 0 3 4 2 REFERENCE VOLTAGE (V) 1091/2/3/4 G19 1.25 VCC = 5V 1.00 0.75 0.50 0.25 0 1.25 OFFSET ERROR (LSB) 0.75 0.
PAGE 8
LTC1091/LTC1092 LTC1093/LTC1094 U W TYPICAL PERFOR A CE CHARACTERISTICS LTC1092/LTC1093/LTC1094 Reference Current vs Temperature 1000 0.6 INPUT CHANNEL LEAKAGE CURRENT (nA) REFERENCE CURRENT (mA) VREF = 5V 0.5 0.4 0.3 0.2 0.
PAGE 9
LTC1091/LTC1092 LTC1093/LTC1094 U U U PI FU CTIO S VREF (Pin 11)(LTC1093): Reference Input. The reference input must be kept free of noise with respect to AGND. CLK (Pin 15/Pin 18): Shift Clock. This clock synchronizes the serial data transfer. REF +, REF – (Pins 13, 14 )(LTC1094): Reference Input. The reference input must be kept free of noise with respect to AGND. VCC (Pin 16)(LTC1093): Positive Supply.
PAGE 10
LTC1091/LTC1092 LTC1093/LTC1094 TEST CIRCUITS Load Circuit for tdDO, t r, t f On- and Off-Channel Leakage Current 5V 1.4V ION A ON-CHANNEL 3k IOFF DOUT A TEST POINT 100pF OFFCHANNELS POLARITY 1091/2/3/4 TC02 1091/2/3/4 TC01 Voltage Waveforms for DOUT Rise and Fall Times, t r, t f Voltage Waveforms for DOUT Delay Time, tdDO 2.4V DOUT 0.4V CLK 0.8V tr tf tdDO 1091/2/3/4 TC04 2.4V Voltage Waveforms for tdis DOUT 0.4V 2.
PAGE 11
LTC1091/LTC1092 LTC1093/LTC1094 TEST CIRCUITS Voltage Waveforms for ten LTC1092 CS CLK 1 B9 DOUT 0.4V 1091/2/3/4 TC08 ten LTC1093/LTC1094 CS DIN START 1 CLK 3 2 4 5 6 7 DOUT 0.4V ten 1091/2/3/4 TC09 U W U UO APPLICATI B9 S I FOR ATIO The LTC1091/LTC1092/LTC1093/LTC1094 are data acquisiton components that contain the following functional blocks: 1. 10-Bit Successive Approximation A/D Converter 2. Analog Multiplexer (MUX) 3. Sample-and-Hold (S/H) 4.
PAGE 12
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO sequence, providing easy interface to MSB- or LSB-first serial ports. The following disussion applies to the configuration of the LTC1091/LTC1093/LTC1094. CS DIN 1 DIN 2 DOUT 2 DOUT 1 The LTC1091/LTC1093/LTC1094 clock data into the DIN input on the rising edge of the clock.
PAGE 13
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO LTC1092 Operating Sequence tCYC CS CLK DOUT Hi-Z B9 B1 tSMPL B0 B9 B1 tSMPL tCONV 1091/2/3/4 AI05 LTC1093/LTC1094 Operating Sequence Example: Differential Inputs (CH4+, CH5–), Unipolar Mode MSB-First Data (MSBF = 1) tCYC CS CLK START SEL1 UNI DIN DOUT DON’T CARE Hi-Z SGL/ ODD/ DIFF SIGN MSBF SEL0 B9 B1 Hi-Z B0 FILLED WITH ZEROS tCONV 1091/2/3/4 AI06 tSMPL LSB-First Data (MSBF = 0) tCYC CS CLK START SEL1 UNI DI
PAGE 14
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO Start Bit The first “logical one” clocked into the DIN input after CS goes low is the start bit. The start bit initiates the data transfer. The LTC1091/LTC1093/LTC1094 will ignore all leading zeros which precede this logical one. After the start bit is received, the remaining bits of the input word will be clocked in. Further inputs on the DIN pin are then ignored until the next CS cycle.
PAGE 15
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO MSB-First/LSB-First (MSBF) Unipolar Output Code (UNI = 1) The output data of the LTC1091/LTC1093/LTC1094 is programmed for MSB-first or LSB-first sequence using the MSBF bit. When the MSBF bit is a logical one, data will appear on the DOUT line in MSB-first format. Logical zeros will be filled in indefinitely following the last data bit to accommodate longer word lengths required by some microprocessors.
PAGE 16
LTC1091/LTC1092 LTC1093/LTC1094 U W U UO APPLICATI S I FOR ATIO 3. Accommodating Microprocessors with Different Word Lengths eliminates one 8-bit transfer and positions data right justified inside the MPU. The LTC1091/LTC1093/LTC1094 will fill zeros indefinitely after the transmitted data until CS is brought high. At that time the DOUT line is disabled. This makes interfacing easy to MPU serial ports with different transfer increments including 4 bits (e.g., COP400) and 8 bits (e.g.
PAGE 17
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO MSBF LATCHED BY LTC1091 CS 1 2 START SGL/ DIFF 3 4 CLK DATA (DIN/DOUT) ODD/ SIGN MSBF B9 B8 • • • LTC1091 CONTROLS DATA LINE AND SENDS A/D RESULT BACK TO MPU MPU CONTROLS DATA LINE AND SENDS MUX ADDRESS TO LTC1091 PROCESSOR MUST RELEASE DATA LINE AFTER 4TH RISING CLK AND BEFORE THE 4TH FALLING CLK LTC1091 TAKES CONTROL OF DATA LINE ON 4TH FALLING CLK 1091/2/3/4 F02 Figure 2.
PAGE 18
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO Motorola SPI (MC68HC05C4, MC68HC11) The MC68HC05C4 has been chosen as an example of an MPU with a dedicated serial port. This MPU transfers data MSB first and in 8-bit increments. With two 8-bit transfers, the A/D result is read into the MPU. The first 8-bit transfer sends the DIN word to the LTC1091 and clocks B9 and B8 of the A/D conversion result into the processor.
PAGE 19
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO Interfacing to the Parallel Port of the Intel 8051 Family LABEL MOV SETB CLR MOV LOOP 1 RLC CLR MOV SETB DJNZ MOV CLR MOV LOOP MOV RLC SETB CLR DJNZ MOV MOV SETB CLR CLR RLC MOV RRC RRC MOV SETB The Intel 8051 has been chosen to demonstrate the interface between the LTC1091 and parallel port microprocessors. Normally, the CS, SCLK and DIN signals would be generated on three port lines and the DOUT signal read on a 4th port line.
PAGE 20
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO 2 1 0 OUTPUT PORT SERIAL DATA MPU 3-WIRE SERIAL INTERFACE TO OTHER PERIPHERALS OR LTC1094s 3 3 3 3 CS LTC1094 CS LTC1094 CS LTC1094 8 CHANNELS 8 CHANNELS 8 CHANNELS LTC1091-4 F03 Figure 3. Several LTC1094s Sharing One 3-Wire Serial Interface Sharing the Serial Interface The LTC1094 can share the same 2- or 3-wire serial interface with other peripheral components or other LTC1094s (see Figure 3).
PAGE 21
LTC1091/LTC1092 LTC1093/LTC1094 U W U UO APPLICATI S I FOR ATIO 3. Analog Inputs Because of the capacitive redistribution A/D conversion techniques used, the analog inputs of the LTC1091/ LTC1092/LTC1093/LTC1094 have capacitive switching input current spikes. These current spikes settle quickly and do not cause a problem.
PAGE 22
LTC1091/LTC1092 LTC1093/LTC1094 U W U UO APPLICATI S I FOR ATIO “–” Input Settling Input Op Amps At the end of the sample phase the input capacitor switches to the “–” input and the conversion starts (see Figure 8). During the conversion, the “+” input voltage is effectively “held” by the sample-and-hold and will not affect the conversion result. However, it is critical that the “–” input voltage settle completely during the first CLK cycle of the conversion time and be free of noise.
PAGE 23
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO resistor must be used, errors can be eliminated by increasing the cycle time as shown in the typical curve of Maximum Filter Resistor vs Cycle Time. Input Leakage Current 5mV/DIV 1µs/DIV 1091-4 F09 Figure 9. Adequate Settling of Op Amp Driving Analog Input Input leakage currents can also create errors if the source resistance gets too large.
PAGE 24
LTC1091/LTC1092 LTC1093/LTC1094 U W U UO APPLICATI S I FOR ATIO Differential Inputs With differential inputs, the A/D no longer converts just a single voltage but rather the difference between two voltages. In this case, the voltage on the selected “+” input is still sampled and held and therefore may be rapidly time varying just as in single-ended mode. However, the voltage on the selected “–” input must remain constant and be free of noise and ripple throughout the conversion time.
PAGE 25
LTC1091/LTC1092 LTC1093/LTC1094 W U U UO APPLICATI S I FOR ATIO 5V reference becomes 0.5LSB with a 1V reference and 2.5LSBs with a 0.2V reference. If this offset is unacceptable, it can be corrected digitally by the receiving system or by offsetting the “–” input to the LTC1092/LTC1093/ LTC1094. 0.5mV/DIV Noise with Reduced VREF 1µs/DIV 1091-4 F14 Figure 14. Poor Reference Settling Can Cause A/D Errors 6. Reduced Reference Operation The minimum reference voltage of the LTC1091 is limited to 4.
PAGE 26
LTC1091/LTC1092 LTC1093/LTC1094 UO TYPICAL APPLICATI S 0°C to 500°C Furnace Exhaust Gas Temperature Monitor with Low Supply Detection 9V VIN 2 J TYPE 8 GND 4 + 56k 4 LT1025A J LT1021-5 0.1µF VIN – 2 6 VOUT + 10µF 20k 1N4148 COMMON 5 LTC1091A 3 7 + 6 LTC1052 1µF 2 CS 47Ω 8 – 4 1 0.1µF 0.1µF 1k 0.1% 0.33µF 3.4k 1% 26 178k 0.
PAGE 27
LTC1091/LTC1092 LTC1093/LTC1094 UO TYPICAL APPLICATI S 0°C to 100°C 0.25°C Accurate Thermistor Based Temperature Measurement System 5V 4.7µF 2N3904 10k ±10% 15k ±10% LTC1094 YSI 44201 0°C TO 100°C 5k AT 25°C 20°C TO –40°C YSI 44201 * 2954Ω 5000Ω CH0 DVCC CH1 AVCC CH2 CLK CH3 CS CH4 DOUT CH5 DIN CH6 REF + CH7 REF – COM AGND + LT1006 – V– DGND 4562Ω TO MCU 1491Ω 1091-4 TA04 *YSI 44007, 44034 OR EQUIVALENT – 55°C to 125°C Thermometer Using Current Output Silicon Sensors 4.
PAGE 28
LTC1091/LTC1092 LTC1093/LTC1094 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. N8 Package 8-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.400* (10.160) MAX 8 7 6 5 1 2 3 4 0.255 ± 0.015* (6.477 ± 0.381) 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( +0.035 0.325 –0.015 8.255 +0.889 –0.381 ) 0.045 – 0.065 (1.143 – 1.651) 0.065 (1.651) TYP 0.100 (2.54) BSC *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
PAGE 29
LTC1091/LTC1092 LTC1093/LTC1094 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. N Package 16-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.770* (19.558) MAX 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 0.255 ± 0.015* (6.477 ± 0.381) 0.130 ± 0.005 (3.302 ± 0.127) 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( +0.035 0.325 –0.015 8.255 +0.889 –0.381 ) 0.045 – 0.065 (1.143 – 1.651) 0.020 (0.508) MIN 0.065 (1.651) TYP 0.125 (3.175) MIN 0.
PAGE 30
LTC1091/LTC1092 LTC1093/LTC1094 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. N Package 20-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 1.040* (26.416) MAX 20 19 18 17 16 15 14 13 12 11 1 2 3 4 5 6 7 8 9 10 0.255 ± 0.015* (6.477 ± 0.381) 0.130 ± 0.005 (3.302 ± 0.127) 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( +0.035 0.325 –0.015 +0.889 8.255 –0.381 ) 0.045 – 0.065 (1.143 – 1.651) 0.020 (0.508) MIN 0.065 (1.651) TYP 0.
PAGE 31
LTC1091/LTC1092 LTC1093/LTC1094 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. SW Package 16-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.398 – 0.413* (10.109 – 10.490) 16 15 14 13 12 11 10 9 0.394 – 0.419 (10.007 – 10.643) NOTE 1 1 0.291 – 0.299** (7.391 – 7.595) 2 3 4 5 6 7 0.093 – 0.104 (2.362 – 2.642) 0.010 – 0.029 × 45° (0.254 – 0.737) 8 0.037 – 0.045 (0.940 – 1.143) 0° – 8° TYP 0.009 – 0.013 (0.229 – 0.330) NOTE 1 0.016 – 0.
PAGE 32
LTC1091/LTC1092 LTC1093/LTC1094 U TYPICAL APPLICATION Micropower, 500V Optoisolated, Multichannel, 10-Bit Data Acquisition System Is Accessed Once Every Two Seconds 4N28s 10k 9V 5V 10k 2N3906 LT1021-5 10k 2N3906 51k C1 150Ω 1Ω 5V 10k + 10µF* LTC1094 8 ANALOG INPUTS 0V TO 5V RANGE 5V CH0 DVCC CH1 AVCC CH2 CLK CH3 CS CH4 DOUT CH5 DIN CH6 REF+ CH7 REF – COM AGND 5.1k ×3 10k C0 150Ω 51k TO 68HC05** 5V 10k MOSI 150Ω 51k TO ADDITIONAL LTC1094s 5.