TC9400 TC9401 TC9402
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TC9400 TC9401 TC9402 CONVERTERS
FEATURES Voltage-to-Frequency
Choice Guaranteed Linearity: TC9401 0.01% TC9400 0.05% TC9402 0.25% (F/V) 100kHz (V/F) Power Dissipation 27mW Single/Dual Supply Operation 7.5V Gain Temperature Stability ppm/°C Programmable Scale Factor
GENERAL DESCRIPTION
TC9400/TC9401/TC9402 low-cost voltage-tofrequency (V/F) converters utilizing power CMOS technology. converters accept variable analog input signal generate output pulse train whose frequency linearly proportional input voltage. devices also used highly-accurate frequency-to-voltage (F/V) converters, accepting virtually input frequency waveform providing linearly-proportional voltage output. complete system only requires addition capacitors, three resistors, reference voltage.
Frequency-to-Voltage
Operation Choice Guaranteed Linearity: TC9401 0.02% TC9400 0.05% TC9402 0.25% Programmable Scale Factor
ORDERING INFORMATION
Part TC9400COD TC9400CPD TC9400EJD TC9401CPD TC9401EJD TC9402CPD TC9402EJD Linearity (V/F) 0.05% 0.05% 0.05% 0.01% 0.01% 0.25% 0.25% Package Temperature Range
APPLICATIONS
Data Acquisition
13-Bit Analog-to-Digital Converters Analog Data Transmission Recording Phase-Locked Loops Frequency Meters/Tachometer Motor Control Demodulation
14-Pin +70°C SOIC (Narrow) 14-Pin +70°C Plastic 14-Pin 40°C +85°C CerDIP 14-Pin +70°C Plastic 14-Pin 40°C +85°C CerDIP 14-Pin +70°C Plastic 14-Pin 40°C +85°C CerDIP
FUNCTIONAL BLOCK DIAGRAM
TC9400 Integrator Capacitor Input Voltage Pulse Output Integrator OpAmp Threshold Detector Shot
Reference Capacitor
Pulse/2 Output
IREF
Reference Voltage
TC9400/1/2-5 11/6/96
3-287
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
ABSOLUTE MAXIMUM RATINGS*
+18V .10mA VOUT -VOUT Common VREF 1.5V Storage Temperature Range 65°C +150°C Operating Temperature Range Device +70°C Device 40°C +85°C Package Dissipation 70°C) 8-Pin CerDIP 800mW 8-Pin Plastic 730mW 8-Pin SOIC .470mW 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 operational sections specifications implied. Exposure Absolute Maximum Rating Conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS: +5V, VGND VREF RBIAS 100k,
Full Scale 10kHz, unless otherwise specified. +25°C, unless temperature range specified 40°C +85°C device, +70°C device). VOLTAGE-TO-FREQUENCY Parameter Definition
Accuracy Linearity Output Deviation From Straight Line Between Normalized Zero Full-Scale Input Output Deviation From Straight Line Between Normalized Zero Reading Full-Scale Input Variation Gain Temperature Change Variation From Ideal Accuracy Correction Zero Adjust Zero Output When Input Zero Variation Zero Offset Temperature Change Full-Scale Analog Input Current Achieve Specified Accuracy Overrange Current Settling Time 0.1% Full Scale Logic Output Voltage (Note Voltage Range Between Output Common
TC9401 TC9400 TC9402
0.004 0.01 0.01 0.05 0.05 0.25
Unit
Full Scale Full Scale
Linearity
0.04
0.08
0.25
0.25
Gain Temperature Drift (Note Gain Variance Zero Offset (Note Zero Temperature Drift (Note Analog Input Full Scale Overrange Response Time Digital Section VSAT 10mA VOUT VOUT Common (Note Pulse Frequency Output Width
ppm/°C Full Scale Nominal µV/°C
Cycle µsec
3-288
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
ELECTRICAL CHARACTERISTICS: (Cont.) +5V, VGND VREF RBIAS 100k, Full Scale 10kHz, unless otherwise specified. +25°C, unless temperature range specified 40°C +85°C device, +70°C device.
FREQUENCY-TO-VOLTAGE Parameter Definition
Supply Current Quiescent (Note Quiescent (Note Supply Supply Reference Voltage VREF -VSS Accuracy Nonlinearity (Note Current Required From Positive Supply During Operation Current Required From Negative Supply During Operation Operating Range Positive Supply Operating Range Negative Supply Range Voltage Reference Input Deviation From Ideal Transfer Function Percentage Full-Scale Voltage Frequency Range Specified Nonlinearity Voltage Required Turn Threshold Detector Voltage Required Turn Threshold Detector Time Between Threshold Crossings Time Between Threshold Crossings
TC9401 TC9400 TC9402
Unit
0.25
Full Scale
0.01 0.02
0.02 0.05
0.05
Input Frequency Range (Note Frequency Input Positive Excursion Negative Excursion Minimum Positive Pulse Width (Note Minimum Negative Pulse Width (Note Input Impedance Analog Outputs Output Voltage (Note Output Loading Supply Current Quiescent (Note Quiescent (Note Supply Supply Reference Voltage VREF -VSS
NOTES:
100k
100k
100k
µsec µsec
Voltage Range Output Specified Nonlinearity Resistive Loading Output Current Required From Positive Supply During Operation Current Required From Negative Supply During Operation Operating Range Positive Supply Operating Range Negative Supply Range Voltage Reference Input
Full temperature range. Guaranteed, Tested. Full temperature range, IOUT 10mA. IOUT 10µA. Threshold Detect Full Temperature Range
10Hz 100kHz.; Guaranteed, Tested 5µsec minimum positive pulse width µsec minimum negative pulse width. nsec. 2k.; Tested Full temperature range, 0.1V. 3-289
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
CONFIGURATIONS 14-Pin Plastic DIP/CerDIP
IBIAS ZERO VREF VREF TC9400 TC9401 TC9402 AMPLIFIER THRESHOLD DETECTOR FREQ/2 OUTPUT COMMON PULSE FREQ
14-Pin SOIC (Narrow)
IBIAS ZERO TC9400 TC9401 TC9402 AMPLIFIER THRESHOLD DETECTOR FREQ/2 OUTPUT COMMON PULSE FREQ
INTERNAL CONNECTION
DESCRIPTIONS
Symbol IBIAS Zero VREFOUT VREF Pulse Freq Output Common Freq/2 Threshold Detect Amplifier Description This sets bias current TC9400. Connect through resistor. text. frequency adjustment input. text. Input current connection converter. Negative power supply voltage connection, typically Reference capacitor connection. Analog ground. Voltage reference input, typically Frequency output. This open drain output will pulse each time Freq threshold detector limit reached. pulse rate proportional input voltage. Source connection open drain output FETs. text. This open drain output square wave half frequency pulse output (pin Output transitions this occur rising edge Input threshold detector. This frequency input during operation. Output integrator amplifier. internal connection Positive power supply connection, typically +5V.
3-290
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
THRESHOLD DETECT fOUT 3µsec DELAY THRESHOLD DETECTOR
fOUT/2 SELFSTART VREF CREF 180pF ZERO ADJUST 12pF 60pF OpAmp IBIAS RBIAS 100k REFERENCE VOLTAGE (TYPICALLY -5V) VREF TC9400 TC9401 TC9402 OUTPUT COMMON
CINT 820pF INPUT -10V OFFSET ADJUST 510k
Figure
Converter
VOLTAGE-TO-FREQUENCY (V/F) CIRCUIT DESCRIPTION
TC9400 converter operates principal charge balancing. operation TC9400 easily understood referring Figure input voltage (VIN) converted current (IIN) input resistor. This current then converted charge integrating capacitor shows linearly decreasing voltage output amp. lower limit output swing threshold detector, which causes reference voltage applied reference capacitor time period long enough charge capacitor reference voltage. This action reduces charge integrating capacitor fixed amount CREF VREF), causing output step finite amount. TELCOM SEMICONDUCTOR, INC. charging period, CREF shorted out. This dissipates charge stored reference capacitor, that when output again crosses zero system ready recycle. this manner, continued discharging integrating capacitor input balanced fixed charges from reference voltage. input voltage increased, number reference pulses required maintain balance increases, which causes output frequency also increase. Since each charge increment fixed, increase frequency with voltage linear. addition, accuracy output pulse width does directly affect linearity V/F. pulse must simply long enough full charge transfer take place.
3-29
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
µsec fOUT
fOUT/2
VREF NOTES: adjust fMIN, 10mV adjust offset 10Hz output. adjust fMAX, adjust VREF output. increase fOUT 100kHz, change CREF CINT 75pF. high-performance applications, high-stability components RIN, CREF, VREF (metal film resistors glass capacitors). Also, separate output ground (pin from input ground (pin
CREF CINT
Figure Output Waveforms
TC9400 contains "self-start" circuit ensure converter always operates properly when power first applied. event that, during power-on, output below threshold CREF already charged, positive voltage step will occur. op-amp output will continue decrease until crosses -3.0V threshold "self-start" comparator. When this happens, internal resistor connected op-amp input, which forces output positive until TC9400 normal operating mode. TC9400 utilizes power CMOS processing input bias offset currents with very power dissipation. open-drain N-channel output FETs provide high voltage high current sink capability.
FUNCTIONS Threshold Detector Input
mode, this input connected amplifier output (pin triggers µsec pulse when input voltage passes through threshold. mode, input frequency applied this input. nominal threshold detector halfway between power supplies, (VDD VSS)/2 ±400mV. TC9400's charge balancing technique dependent precision comparator threshold, because threshold only sets lower limit op-amp output. op-amp's peak-to-peak output swing, which determines frequency, only influenced external capacitors VREF.
VOLTAGE-TO-TIME MEASUREMENTS
TC9400 output measured time domain well frequency domain. Some microcomputers, example, have extensive timing capability limited counter capability. Also, response time time domain measurement only period between output pulses, while frequency measurement must accumulate pulses during entire counter timebase period. Time measurements made from either TC9400's Pulse Freq output from Freq/2 output. Freq/2 output changes state rising edge Pulse Freq Out, Freq/2 symmetrical square wave half pulse output frequency. Timing measurements therefore made between successive Pulse Freq pulses, while Freq/2 high low).
3-292
Pulse Freq
This output open-drain N-channel which provides pulse waveform whose frequency proportional input voltage. This output requires pull-up resistor interfaces directly with MOS, CMOS, logic.
Freq/2
This output open-drain N-channel which provides square wave one-half frequency pulse frequency output. Freq/2 output will change state rising edge Pulse Freq Out. This output requires pullup resistor interfaces directly with MOS, CMOS, logic.
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
Output Common
sources both Freq/2 Pulse Freq connected this pin. output level swing from drain voltage ground supply obtained connecting this appropriate point.
VREF
charging current CREF supplied through this pin. When output reaches threshold level, this internally connected reference voltage charge, equal VREF CREF, removed from integrator capacitor. After about µsec, this internally connected summing junction discharge CREF. Break-before-make switching ensures that reference voltage directly applied summing junction.
RBIAS
external resistor, connected VSS, sets bias point TC9400. Specifications TC9400 based RBIAS 100k ±10%, unless otherwise noted. Increasing maximum frequency TC9400 beyond 100kHz limited pulse width Pulse Output (typically 3µsec). Reducing RBIAS will decrease pulse width increase maximum operating frequency, linearity errors will also increase. RBIAS reduced 20k, which will typically produce maximum full scale frequency 500kHz.
CONVERTER DESIGN INFORMATION Input/Output Relationships
output frequency (fOUT) related analog input voltage (VIN) transfer equation: Frequency (VREF) (CREF)
Amplifier
output stage operational amplifier. During operation, negative-going ramp signal available this pin. mode, voltage proportional frequency input generated.
External Component Selection
value this component chosen give fullscale input current approximately 10µA: Full Scale 10µA Example: 10µA
Zero Adjust
This noninverting input operational amplifier. low-frequency point determined adjusting voltage this pin.
inverting input operational amplifier summing junction when connected mode. input current 10µA specified, overrange current 50µA used without detrimental effect circuit operation. connects summing junction operational amplifier. Voltage sources cannot attached directly, must buffered external resistors.
Note that value approximation exact relationship defined transfer equation. practice, value typically would trimmed obtain fullscale frequency full scale (see "Adjustment Procedure"). Metal film resistors with tolerance better recommended high-accuracy applications because their thermal stability low-noise generation. CINT exact value critical related CREF relationship: 3CREF CINT CREF. Improved stability linearity obtained when CINT 4CREF. Low-leakage types recommended, although mica ceramic devices used applications where their temperature limits exceeded. Locate close possible pins
VREF
reference voltage from either precision source supply applied this pin. Accuracy TC9400 dependent voltage regulation temperature characteristics reference circuitry. Since TC9400 charge balancing converter, reference current will equal input current. this reason, impedance reference voltage source must kept enough prevent linearity errors. linearity 0.01%, reference impedance less recommended. 0.1µF bypass capacitor should connected from VREF ground. TELCOM SEMICONDUCTOR, INC.
3-293
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
CREF exact value critical used trim full-scale frequency (see "Input/Output Relationships"). Glass film trimmer capacitors recommended because their stability leakage. Locate close possible pins VDD, Power supplies recommended. highaccuracy requirements, 0.05% line load regulation 0.1µF disc decoupling capacitors located near pins recommended.
Improved Single Supply Converter Operation
TC9400 which operates from single variable power source shown Figure This circuit uses Zener diodes stable biasing levels TC9400. Zener diodes also provide reference voltage, output impedance temperature coefficient Zeners will directly affect power supply rejection temperature performance. Full scale adjustment accomplished trimming input current. Trimming reference voltage recommended high accuracy applications unless used buffer, because TC9400 requires impedance reference (see VREF description section more information). circuit Figure will directly interface with CMOS logic operating 15V. CMOS logic accommodated connecting output pullup resistors supply. optoisolator also used isolated output required.
Adjustment Procedure
Figure shows circuit trimming zero location. Full scale trimmed adjusting RIN, VREF, CREF. Recommended procedure 10kHz full-scale frequency follows: trim zero adjust circuit obtain 10Hz output frequency. trim either RIN, VREF, CREF obtain 10kHz output frequency. adjustments performed this order, there should interaction they should have repeated.
+10V +25°C
CREF (pF) +12pF
100kHz VREF
Figure
Recommended CREF VREF
3-294
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
(FIXED)
GAIN ADJUST OFFSET ADJUST 0V-10V
fOUT fOUT/2
0.01
VREF 0.01 TC9400
fOUT
(V2-V7) (CREF) (VIN-V2) (V+-V2) IIN= (0.9 R1+0.2
Figure Fixed Voltage Single Supply Operation
+15V 1.2k* THRESHOLD DETECT CREF CREF TC9400
910k GAIN 100k CINT
5.1VZ
100k 910k 5.1VZ
ZERO ADJUST 0.1µ BIAS 100k
fOUT OUTPUT FREQUENCY
fOUT/2
OUTPUT COMMON
INPUT VOLTAGE 10V)
OFFSET ANALOG GROUND
DIGITAL GROUND
COMPONENT SELECTION
FREQ. CREF 2200pF 180pF 27pF CINT 4700pF 470pF 75pF
Figure
Voltage Frequency 3-295
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
FREQUENCY-TO-VOLTAGE (F/V) CIRCUIT DESCRIPTION
When used converter, TC9400 generates output voltage linearly proportional input frequency waveform. Each zero crossing threshold detector's input causes precise amount charge CREF VREF) dispensed into amp's summing junction. This charge turn flows through feedback resistor, generating voltage pulses output amp. capacitor (CINT) across RINT averages these pulses into voltage which linearly proportional input frequency.
Input Voltage Levels
input frequency applied Threshold Detector input (Pin 11). discussed circuit section this data sheet, threshold approximately (VDD VSS) ±400mV. 11's input voltage range extends from about below threshold. voltage goes more than volts below threshold, mode startup comparator will turn corrupt output voltage. Threshold Detector input about hysteresis. applications, input voltage levels TC9400 ±400mV, minimum. frequency source being measured unipolar, such CMOS operating from source, then coupled level shifter should used. such circuit shown Figure level shifter circuit Figure used single supply applications. resistor divider ensures that input threshold will track supply voltages. diode clamp prevents input from going enough negative direction turn startup comparator. diode's forward voltage decreases mV/°C, high ambient temperature operation diodes series recommended.
CONVERTER DESIGN INFORMATION Input/Output Relationships
output voltage related input frequency (fIN) transfer equation: VOUT [VREF CREF RINT] fIN. response time change equal (RINT CINT). amount ripple VOUT inversely proportional CINT input frequency. CINT increased lower ripple. Values 100µF perfectly acceptable frequencies. When TC9400 used single-supply mode, VREF defined voltage difference between
Frequency Input
0.01µF
TC9400 IN914 1.0M
Frequency Input
0.01µF
TC9400 IN914 1.0M
0.1µF
Supply
Figure 3-296 Frequency Input Level Shifter
Single Supply
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
TC9400A TC9401A TC9402A fOUT/2
OUTPUT COMMON THRESHOLD DETECT
FIGURE
µsec DELAY THRESHOLD DETECTOR
fOUT OPTIONAL BUFFER NEEDED
VREF 12pF OFFSET ADJUST 100k 2.2k ZERO ADJUST IBIAS VREF (TYPICALLY -5V) VREF 60pF RINT CREF EQUATION, PAGE CINT 1000pF
Figure
Converter
Input Buffer
0.5µsec 5.0µsec
INPUT
fOUT DELAY 3µsec fOUT/2
fOUT fOUT/2 used mode. However, these outputs useful some applications, such buffer feed additional circuitry. Then, fOUT will follow input frequency waveform, except that fOUT will high 3µsec after goes high; fOUT/2 will squarewave with frequency one-half fOUT. these outputs used, pins should connected ground.
Figure Digital Outputs
3-297
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
6.2V .01µF
TC9400
ZERO ADJUST VREFOUT 47pF .001µF VOUT
500k 100k Offset Adjust Frequency Input 0.01µF
1.0k
IN914
1.0M
IBIAS
VREF
0.1µF
1.0k 100k
Note: output referenced which 6.2V (Vz). frequency meter applications, meter with series-scaling resistor placed across pins
Figure Single Supply Converter
Output Filtering
output TC9400 sawtooth ripple superimposed level. ripple will rejected TC9400 output converted digital value integrating analog digital converter, such TC7107 TC7109. ripple also reduced increasing value integrating capacitor, although this will reduce response time converter. sawtooth ripple output eliminated without affecting F/V's response time using circuit Figure circuit capacitance multiplier, where output coupling capacitor multiplied gain amp. moderately fast amp, such TL071, should used.
VREFOUT 47pF
TC9400
.001µF
.01µF
0.1µF VOUT TL07
Figure 3-298
Ripple Filter
TELCOM SEMICONDUCTOR, INC.
VOLTAGE-TO-FREQUENCY/ FREQUENCY-TO-VOLTAGE CONVERTERS TC9400 TC9401 TC9402
POWER-ON RESET
mode, TC9400 output voltage will occasionally maximum value when power first applied. This condition remains until first pulse applied fIN. most frequency-measurement applications this problem, because proper operation begins soon frequency input applied. some cases, however, TC9400 output must zero power-on without frequency input. such cases, capacitor connected from will usually sufficient pulse TC9400 provide power-on reset (see Figure 11A). Where predictable power-on operation critical, more complicated circuit, such Figure 11B, required.
1000pF THRESHOLD DETECTOR TC9400
100k CLRA
9400
CD4538
Figure
Power-On Operation/Reset
TELCOM SEMICONDUCTOR, INC.
3-299
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