3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFEREN

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3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFEREN

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3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811 TC811
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS
Differential Reference Input Display Hold Function Fast Over-Range Recovery, Guaranteed Next Reading Accuracy Temperature Drift Internal Reference 35ppm/°C (Typ) Guaranteed Zero Reading With Zero Input Noise 15µVp-p High Resolution (0.05%) Wide Dynamic Range High Impedance Differential Input Input Leakage Current (Typ) 10pA Direct Drive External Components Precision Null Detection with True Polarity Zero Crystal Clock Oscillator Available DIP, Compact Flat Package PLCC Convenient Battery Operation with Power Dissipation (600µA Typical, Maximum)
TYPICAL APPLICATIONS
Thermometry Digital Meters Voltage/Current/Power Measurement Capacitance/Inductance Fluid Flow Rate/Viscosity Humidity Position Panel Meters LVDT Indicators Portable Instrumentation Digital Scales Process Monitors Gaussometers Photometers
ORDERING INFORMATION
Part TC811CKW TC811CPL Package Temp. Range VREF Temp.
44-Pin PQFP +70°C ppm/°C 40-Pin Plastic +70°C ppm/°C
FUNCTIONAL BLOCK DIAGRAM
TYPICAL SEGMENT OUTPUT 0.5mA SEGMENT OUTPUT
DISPLAY
TC811CPL
INTERNAL DIGITAL GROUND BACKPLANE
VREF
CREF
VREF
RINT BUFF
CINT VINT SEGMENT DRIVERS
INTEGRATOR
DIGITAL SECTION SEGMENT DECODE SEGMENT DECODE SEGMENT DECODE
DATA LATCH
COMPARATOR
THOUSANDS HUNDREDS TENS UNITS
TEMPCO VREF
ANALOG COMMON
3.0V
SWITCH DRIVERS FROM COMPARATOR OUTPUT CLOCK fOSC CONTROL LOGIC
6.2V
INTERNAL DIGITAL GOUND
TEST
HLDR
470k 10pF 20pF
TC811-7 11/5/96 TelCom Semiconductor reserves right make changes circuitry specifications devices.
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
GENERAL DESCRIPTION
TC811 power, 3-1/2 digit, display analog-to-digital converter. This device incorporates both display hold feature differential reference inputs. crystal oscillator, which only requires pins, permits added features while retaining 40-pin package. additional feature "Integrator Output Zero" phase which guarantees rapid input overrange recovery. TC811 display hold (HLDR) function used "freeze" display. displayed reading will remain indefinitely long HLDR held high. Conversions continue output data display latches updated. TC811 also includes differential reference easy ratiometric measurements. Circuits which 7106/26/36 easily upgraded include hold function with TC811. TC811 improved internal zener reference voltage circuit which maintains Analog Common temperature drift 35ppm/°C (typical) 75ppm/°C (maximum). This represents improvement four times over similar 3-1/2 digit converters, eliminating need costly, space consuming external reference source. TC811 limits linearity error less than count both 200mV 2.00V full-scale ranges. Rollover error-the difference readings equal magnitude opposite polarity input signals-is below count. High impedance differential inputs offer leakage currents 1012 input impedance. 15µVp-p noise performance guarantees "rock solid" reading. Auto Zero cycle guarantees zero display readout zero volt input. single chip CMOS TC811 incorporates active devices 3-1/2 digit analog digital converter directly drive display. On-board oscillator, precision voltage reference display segment backplane drivers simplify system integration, reduce board space requirements lower total cost. cost, high resolution (0.05%) indicating meter requires only TC811, display, five resistors, capacitors, crystal, battery. Compact, hand held multimeter designs benefit from TelCom Semiconductor small footprint package option. TC811 uses dual slope conversion technique which will reject interference signals converters integration time multiple interference signal period. This especially useful industrial measurement environments where 400Hz line frequency signals present.
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage .15V Analog Input voltage (Either Input)1 Reference Input Voltage Clock Input TEST Power Dissipation2 70°C) 44-Pin Flat Package .1.00W 40-Pin Plastic 1.23W Operating Temperature Range Commercial Package +70°C Industrial Package 25°C +85°C Storage Temperature Range 65°C +150°C Lead Temperature (Soldering, sec) +300°C
*Static-sensitive device. Unused devices must stored conductive material. Protect devices from static discharge static fields. Stresses above those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only functional operation device these other conditions above those indicated operation sections specifications implied. Exposure absolute maximum rating conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS: VSupply fCLOCK 32.768kHz, 25°C, unless otherwise noted.
Symbol Input
CMRR Zero Input Reading Zero Reading Drift Ratiometric Reading Linearity Error Roll Over Error Noise Input Leakage Current Common-Mode Rejection 200mV 70°C VREF, VREF 100mV 200mV 2.000V VIN- VIN+ 200mV 200mV ±1V, 200mV 000.0 ±000.0 999/1000 ±0.2 ±0.2 +000.0 1000 Digital Reading µV/°C Digital Reading Counts Counts µVP-P µV/V
Parameter
Test Conditions
Unit
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
ELECTRICAL CHARACTERISTICS: VSupply fCLOCK 32.768kHz, 25°C, unless otherwise noted.
Symbol
TCSF
Parameter
Scale Factor Temperature Coefficient Analog Common Temperature Coefficient
Test Conditions
199mV, 70°C (ext. VREF 0ppm) 250K from Analog Common 70°C Commercial Industrial 250k from Analog Common fOSC 16kHz fOSC 48kHz
Unit
ppm/°C
Analog Common Section
VCTC 3.05 3.35 Test +1.5 ppm/°C ppm/°C Volts VP-P VP-P
Analog Common Voltage Input Resistance Input Voltage Input High Voltage Segment Drive Voltage Backplane Drive Voltage Power Supply Current
Hold Input Section
ISUP
Drive Section3
Power Supply
NOTES: Input voltages exceed supply voltages when input current limited 100µA. Dissipation rating assumes device mounted with leads soldered printed circuit board. Backplane drive phase with segment drive "segment off" 180° phase "segment on." Frequency times conversion rate. Average component less than 50mV.
CONFIGURATIONS
10's 100's 1000's
HLDR
NORMAL CONFIGURATION TC811CPL (40-PIN PDIP) TEST REF+ CREF+ CREF- VREF- ANALOG COMMON VBUFF (BACKPLANE) 100's 10's
TEST
VREF+ CREF CREF VREF-
BUFF
TC811CKW (PQFP)
HLDR
(MINUS SIGN)
INTERNAL CONNECTION
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
DESCRIPTION
40-Pin Plastic
Symbol
HLDR VINT VBUFF VREF CREF CREF VREF TEST OSC2 OSC1
Description
Hold pin, logic holds present display reading. Activates section units display. Activates section units display. Activates section units display. Activates section units display. Activates section units display. Activates section units display. Activates section units display. Activates section tens display. Activates section tens display. Activates section tens display. Activates section tens display. Activates section tens display. Activates section tens display. Activates section hundreds display. Activates section hundreds display. Activates section hundreds display. Activates section hundreds display. Activates both halves thousands display. Activates negative polarity display. Backplane drive output. Activates section hundreds display. Activates section hundreds display. Activates section hundreds display. Activates section tens display. Negative power supply voltage. Integrator output, connection CINT. Buffer output, connection RINT. Integrator input, connection CAZ. Analog input low. Analog input high. Analog Common: Internal zero reference. Reference input low. Negative connection reference capacitor. Positive connection reference capacitor. Reference input high. segment test when pulled high (V+). Positive power supply voltage. Crystal oscillator output. Crystal oscillator input.
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
0.1µF ANALOG COMMON 180k 0.47 VBUFF TC811 9-19 SEGMENT 22-25 DRIVE 240k HLDR VREF OSC1 20pF 470k 10pF ANALOG COMMON (PIN CONVERSION/SEC MINUS SIGN BACKPLANE
ANALOG INPUT SIGNAL
INTEGRATOR COMPARATOR VARIABLE REFERENCE INTEGRATE TIME
ANALOG INPUT 0.01µF
SWITCH DRIVER VOLTAGE PHASE CONTROL CONTROL LOGIC POLARITY CONTROL CLOCK
VINT OSC2
0.068µF
INTEGRATOR OUTPUT
DISPLAY
VFULL SCALE VFULL SCALE
FIXED SIGNAL INTEGRATE TIME
Figure Typical Operating Circuit
Figure Basic Dual Slope Converter
(All Designations Refer 40-Pin Package) TC811 dual slope, integrating analog-to-digital converter. understanding dual slope conversion technique will user following detailed TC811 theory operation following this section. conventional dual slope converter measurement cycle distinct phases: Input Signal Integration Reference Voltage Integration (Deintegration) Referring Figure unknown input signal converted integrated from zero fixed time period (TINT), measured counting clock pulses. constant reference voltage opposite polarity then integrated until integrator output voltage returns zero. reference integration (deintegration) time (TDEINT) then directly proportional unknown input voltage (VIN). simple dual slope converter, complete conversion requires integrator output "ramp-up" from zero "ramp-down" back zero. simple mathematical equation relates input signal, reference voltage integration time: tINT VREF tDEINT VIN(t) RINT CINT RINT CINT
NORMAL MODE REJECTION (dB)
GENERAL THEORY OPERATION Dual-Slope Conversion Principles
MEASUREMENT PERIOD 0.1/T INPUT FREQUENCY 10/T
Figure Normal-Mode Rejection Dual Slope Converter
constant VINT: VREF
tDEINT tINT
where: VREF Reference voltage tINT Integration Time tDEINT Deintegration Time
COUNTER
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
Accuracy dual slope converter unrelated integrating resistor capacitor values long they stable during measurement cycle. inherent benefit dual slope technique noise immunity. Noise spikes integrated averaged zero during integration periods, making integration ADCs immune large conversion errors that plague successive approximation converters high noise environments. Interfering signals, with frequency components multiples averaging (integrating) period, will attenuated. (see Figure Integrating ADCs commonly operate with signal integration period multiple 50/60Hz power line period.
1000 1-2000 11-140 910-2900 4000
DE-INT
THEORY OPERATION Analog Section
addition basic integrate deintegrate dualslope cycles discussed above, TC811 design incorporates "Integrator Output Zero" cycle "Auto Zero" cycle. These additional cycles ensure integrator starts (even after severe overrange conversion) that offset voltage errors (buffer amplifier, integrator comparator) removed from conversion. true digital zero reading assured without external adjustments. complete conversion consists four distinct phases: Integrator Output Zero Cycle Auto Zero Cycle Signal Integrate Cycle Reference Deintegrate Cycle
Figure Conversion Timing During Normal Operation
1000
DE-INT
2001-2090 31-640
300-910 4000
Figure Conversion Timing During Overrange Operation
Integrator Output Zero Cycle
This phase guarantees that integrator output zero volts before system zero phase entered, ensuring that true system offset voltages will compensated even after overrange conversion. duration this phase variable, being function number counts (clock cycles) required deintegration. Integrator Output Zero cycle will last from counts non-over-range conversions from counts overrange conversions.
Auto Zero duration from 2,900 counts non-over-range conversions from counts overrange conversions.
Signal Integration Cycle
Upon completion Auto Zero cycle, Auto Zero loop opened internal differential inputs connect VIN+ VIN-. differential input signal then integrated fixed time period which, TC811 1000 counts (4000 clock periods). externally clock frequency divided four before clocking internal counters. integration time period TINT 4000 fOSC
Auto Zero Cycle
During Auto Zero cycle, differential input signal disconnected from measurement circuit opening internal analog switches internal nodes shorted Analog Common ref.) establish zero input condition. Additional analog switches close feedback loop around integrator comparator permit comparator offset voltage error compensation. voltage established then compensates internal device offset voltages during measurement cycle. Auto Zero cycle residual typically 15µV.
differential input voltage must within device common-mode range when converter measured system share same power supply common (ground). converter measured system share same power supply common, battery powered applications, VIN- should tied Analog Common.
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
Polarity determined signal integration phase. sign "true polarity" indication that signals less than correctly determined. This allows precision null detection which limited only device noise Auto Zero residual offsets.
Digital Section
TC811 contains segment drivers necessary directly drive 3-1/2 digit liquid crystal display (LCD). backplane driver included. backplane frequency external clock frequency divided 800. three conversions/second backplane frequency 60Hz with nominal amplitude. When segment driver phase with backplane signal segment "OFF". phase segment drive signal causes segment "ON" visible. This drive configuration results negligible voltage across each segment. This insures long display life. polarity segment driver "ON" negative analog inputs. reversed then this indicator would reverse.
Reference Integrate (Deintegrate) Cycle
reference capacitor, which charged during Auto Zero cycle, connected input integrating amplifier. internal sign logic insures that polarity reference voltage always connected phase which opposite that input voltage. This causes integrator ramp back zero constant rate which determined reference potential. amount time required (TDEINT) integrating amplifier reach zero directly proportional amplitude voltage that integrating capacitor (VINT) during integration cycle: RINT CINT VINT VREF digital reading displayed TDEINT VREF oscillator frequency divided prior clocking internal decade counters. four phase measurement cycle takes total 4000 counts 16000 clock pulses. 4000 count cycle independent input signal magnitude polarity. Each phase measurement cycle following length: Digital Count 1000 Auto Zero: 2900 Counts Signal Integrate: 1000 Counts This time period fixed. integration period 4000 TINT 1000 Counts fOSC Where fOSC crystal oscillator frequency. Reference Integrate: 2000 Counts Integrator Output Zero: Counts TC811 replace ICL7106/26/36 circuits which require both hold function differential reference. TC811 offers greatly improved internal reference temperature coefficient, which often eliminate need external reference. Some minor component changes required upgrade existing designs, reduce power dissipation, improve overall performance. (see Oscillator Components)
TEST Function (TEST)
TC811, when TEST pulled logical "HIGH", segments turned "ON". display will read "-1888". During this mode segments have constant voltage impressed. leave display this mode more than several minutes. displays destroyed operated with levels extended periods. display FONT segment drive assignment shown Figure
DISPLAY FONT
1000's
100's
10's
Figure Display FONT Segment Assignment
HOLD Reading Input (HLDR)
When HLDR logic "HI" latch will updated. Conversions will continue will updated until HLDR returned "LOW". continuously update display, connect HLDR ground leave open. This input CMOS compatible internal resistance (typical) tied TEST.
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
COMPONENT VALUE SELECTION Auto Zero Capacitor
value Auto Zero capacitor (CAZ) some influence system noise. 0.47µF capacitor recommended 200mV full-scale applications where 1LSB 100µV. 0.10µF capacitor should used 2.0V fullscale applications. capacitor with dielectric absorption (Mylar) required.
Oscillator Components
internal oscillator been designed operate with quartz crystal, such Statek CX-1V series. Such crystals very small available variety standard frequencies. Note that fOSC divided four generate TC811 internal control clock. backplane drive signal derived dividing fOSC 800. achieve maximum rejection ac-line noise pickup, 40kHz crystal should used. This frequency will yield integration period 100msec will reject both 50Hz 60Hz noise. prototyping cost-sensitive applications 32.768kHz watch crystal used, will produce about 25dB line-noise rejection. Other crystal frequencies, from 16kHz 48kHz, also used. Pins make oscillator section TC811. Figures show some typical conversion rate component values. backplane frequency derived dividing oscillator frequency 800. Capacitive loading compromise display performance oscillator much over 48kHz.
Reference Voltage Capacitor -CREF
reference voltage used ramp integrator output voltage back zero during reference integrate cycle stored CREF. 0.1µF capacitor typical. application requires sensitivity 200mV full-scale, increase CREF 1.0µF. Rollover error will held less than count. good quality, leakage capacitor, such Mylar, should used.
Integrating Capacitor CINT
CINT should selected maximize integrator output voltage swing without causing output saturation. Analog common will normally supply differential voltage reference. this case integrator output swing optimum when analog input near full-scale. reading/ second (fOSC 32kHz 40kHz) 200mV, .068µF value suggested. different oscillator frequency used, CINT must changed inverse proportion maintain nominal integrator swing. exact expression CINT CINT 4000 VINT RINT fOSC
Reference Voltage (VREF)
full-scale reading (2000 counts) requires input signal twice reference voltage. some applications scale factor other than unity exist, such between transducer output voltage required digital reading. Assume, example, pressure transducer output 400mV 2000lb/in2. Rather than dividing input voltage two, reference voltage should 200mV. This permits transducer input used directly.
where: fOSC Clock frequency Full-scale input voltage RINT Integrating resistor VINT Desired full-scale integrator output swing CINT must have dielectric absorption minimize roll-over error. polypropylene capacitor recommended.
TC811
OSC1
OSC2
Integrating Resistor -RINT
input buffer amplifier integrator designed with class output stages which have idling currents 6µA. integrator buffer supply drive currents with negligible linearity errors. RINT chosen remain output stage linear drive region large that printed circuit board leakage currents induce errors. 200mV full-scale, RINT should about 180k. 2.0V full-scale requires abut 1.8M.
40.0
470k
10pF
20pF
Figure TC811 Oscillator
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
Oscillator Freq. (kHz)
32.768
Full-Scale Voltage (VFS) 200mV 2.0V RINT CINT RINT CINT
180k 150k 0.068µF 0.068µF
Figure
1.8M 1.5M
0.068µF 0.068µF
DEVICE FUNCTIONAL DESCRIPTION Differential Signal Inputs (VIN (Pin 31), (Pin 30))
TC811 designed with true differential inputs accepts input signals within input stage common mode voltage range (VCM). typical range 1.5V. Common-mode voltages removed from system when TC811 operates from battery floating power source (isolated from measured system) connected Analog Common. (see Figure systems where common-mode voltages exist, 86dB common-mode rejection ratio minimizes error. Common-mode voltages however, affect integrator output level. worse case condition exists large positive exists conjunction with full-scale negative differential signal. negative signal drives integrator output positive along with (Figure such applications integrator output swing reduced below recommended 2.0V full-scale swing. integrator output will swing within 0.3V without increased linearity error.
facing with sensors such load cells temperature sensors. TC811 ideally suited applications handheld multimeters, panel meters, portable instrumentation. reference voltage generated anywhere within power supply range. prevent rollover type errors from being induced large common-mode voltages, CREF should large compared stray node capacitance. 0.1µF capacitor typical value. TC811 offers significantly improved Analog Common temperature coefficient. This provides very stable voltage suitable voltage reference. temperature coefficient Analog Common typically 35ppm/°C.
INPUT BUFFER
INTEGRATOR
Where: 4000 INTEGRATION TIME
INTEGRATION CAPACITOR INTEGRATION RESISTOR
Reference (VREF (Pin 36), VREF (Pin 33))
Unlike ICL7116, TC811 differential reference well "hold" function. differential reference inputs permit ratiometric measurements simplify interFigure Common-Mode Voltage Reduces Available Integrator Swing. (VCOM VIN)
SEGMENT DRIVE
DISPLAY
MEASURED SYSTEM
10pF VBUF VINT OSC1 TC811 OSC2 470k 40kHZ
ANALOG COMMON VREF VREF
POWER SOURCE
Figure Common-Mode Voltage Removed Battery Operation With Analog Common
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
Analog Common (Pin
Analog Common voltage potential approximately 3.0V below This potential guaranteed between 2.70V 3.35V below Analog common tied internally channel capable sinking 100µA. This will hold common line 3.0V below should external load attempt pull common line toward Analog common source current limited 1µA. Analog common therefore easily pulled more negative voltage (i.e. below 3.0V). TC811 connects internal inputs Analog Common during Auto Zero cycle. During reference integrate phase connected Analog Com- mon. externally connected Analog Common, common-mode voltage exists. This rejected converter's 86dB common-mode rejection ratio. battery powered applications, Analog Common usually connected, removing common-mode voltage concerns. systems where connected power supply ground given voltage, Analog Common should connected VIN. Analog Common serves analog section reference common point. TC811 specifically designed operate from battery measurement system where input signals referenced (float) with respect TC811 power source. Analog Common potential 3.0V gives battery life voltage. analog common potential voltage coefficient 0.001%/%. With sufficiently high total supply voltage 7.0V), Analog Common very stable potential with excellent temperature stability (typically 35ppm/°C). This potential used generate TC811 reference voltage. external voltage reference will unnecessary most cases because 35ppm/°C temperature coefficient. TC811 Internal Voltage Reference discussion.
APPLICATIONS INFORMATION Decimal Point Annunciator Drive
TEST connected internally generated digital logic supply ground through resistor. TEST used negative supply external CMOS gate segment drivers. display annunciators decimal points, battery indication, function indication added without adding additional supply. more than should supplied TEST pin. TEST potential approximately below
Internal Voltage Reference
TC811 Analog Common voltage temperature stability been significantly improved. This improved device used upgrade systems design systems without external voltage references. External values need changed, however, noise performance will improved increasing (See Auto Zero Capacitor section). Figure shows Analog Common supplying necessary voltage reference TC811.
4049
TC811
BACKPLANE DECIMAL POINT
TEST
DECIMAL POINTS
TEST (Pin
TEST potential less TEST used negative power supply connection when interfacing TC811 external CMOS logic. TEST tied internally generated negative logic supply through resistor. TEST used sink 1mA. applications section additional information using TEST negative digital logic supply. TEST pulled "HIGH" (V+), segments plus minus sign will activated. operate this mode more than several minutes, because when TEST pulled Segments impressed with voltage which cause damage LCD.
TC811
HDLR
DECIMAL POINT SELECT
"HOLD" ANNUNCIATOR 4030
TEST
Figure Display Annunciator Drivers
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
Liquid Crystal Display Sources
Several manufactures supply standard displays interface with TC811 3-1/2 digit analog-to-digital converter.
TC811 VREF VREF VREF ANALOG COMMON VREF VFULL SCALE 240k
Manufacturer
Crystaloid Electronics
Address/Phone
5282 Hudson Dr., Hudson, 44236 216-655-2429 Airport Blvd., Burlingame, 94010 415-347-9916 3415 Kashikawa St., Torrence, 90505 212-534-0360 Lake St., Lake Mills, 53551 414-648-2361
Representative Part Numbers*
C5335, H5535, T5135, SX440 0801, 0203 LD-B709BZ LD-H7992AZ 3902, 3933, 3903
EPSON
Hamlin, Inc.
Figure TC811 Internal Voltage Reference Connection
*NOTE:
Contact manufacturer full product listing/specifications.
Oscillator Crystal Source
Manufacturer
STATEK
Address/Phone
N-Main Orange, 92668 714-639-7810
Representative Part Numbers
CX-1V 40.0
STANDARD
VREF HLDR
UNKNOWN TC811
Ratiometric Resistance Measurements
TC811 true differential input differential reference make ratiometric readings possible. ratiometric operation, unknown resistance measured with respect known standard resistance. accurately defined reference voltage needed. unknown resistance series with known standard current passed through pair (Figure 11). voltage developed across unknown applied input voltage across known resistor applied reference input. unknown equals standard, input voltage will equal reference voltage display will read 1000. displayed reading determined from following expression: Displayed reading RUNKNOWN RSTANDARD 1000
ANALOG COMMON
Figure Parts Count Ratio Metric Resistance Measurement
display will overrange UNKNOWN RSTANDARD.
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
0.7%/°C
1N914
1N4148 SENSOR
TC811
TC811
VREF VREF COMMON HLDR
VREF VREF COMMON HLDR
Figure Temperature Sensor
Figure Positive Temperature Coefficient Resistor Temperature Sensor
PACKAGE DIMENSIONS 40-Pin Plastic
.555 (14.10) .530 (13.46)
2.065 (52.45) 2.035 (51.49)
.610 (15.49) .590 (14.99)
.200 (5.08) .140 (3.56) .150 (3.81) .115 (2.92) .040 (1.02) .020 (0.51) .015 (0.38) .008 (0.20) .700 (17.78) .610 (15.50) .022 (0.56) .015 (0.38) MIN.
.110 (2.79) .090 (2.29)
.070 (1.78) .045 (1.14)
Dimensions: inches (mm)
3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTER WITH HOLD DIFFERENTIAL REFERENCE INPUTS TC811
PACKAGE DIMENSIONS (CONT.) 44-Pin
MAX. 0.23 (.009) 0.13 (.005)
0.40 (.016) 0.30 (.012)
1.03 (.041) 0.78 (.031)
10.10 (.398) 9.90 (.390) 14.15 (.557) 13.65 (.537)
.080 (.031) TYP.
10.10 (.398) 9.90 (.390) 14.15 (.557) 13.65 (.537)
0.25 (.010) MIN. 2.10 (.083) 1.90 (.075) 2.45 (.096) MAX.
Dimensions: inches (mm)
Sales Offices
TelCom Semiconductor 1300 Terra Bella Avenue P.O. 7267 Mountain View, 94039-7267 TEL: 650-968-9241 FAX: 650-967-1590 E-Mail: liter@c2smtp.telcom-semi.com TelCom Semiconductor Austin Product Center 9101 Burnet Suite Austin, 78758 TEL: 512-873-7100 FAX: 512-873-8236 TelCom Semiconductor H.K. Ltd. Chuk Street, Ground Floor Kong, Kowloon Hong Kong TEL: 852-2324-0122 FAX: 852-2354-9957
Printed U.S.A.

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