Microchip Technology TC9402EJD, TC9401EJD, TC9401CPD, TC9400CPD, TC9400COD Datasheet

TC9400/9401/9402

Voltage-to-Frequency/Frequency-to-Voltage Converters

Features

VOLTAGE-TO-FREQUENCY

• Choice of Linearity

- TC9401: 0.01%

- TC9400: 0.05%

- TC9402: 0.25%

• DC to 100kHz (F/V) or 1Hz to 100kHz (V/F)

• Low Power Dissipation: 27mW (Typ.)

• Single/Dual Supply Operation

- +8V to +15V or ±4V to ±7.5V

• Gain Temperature Stability: ±25 ppm/°C (Typ.)

• Programmable Scale Factor

FREQUENCY-TO-VOLTAGE

• Operation: DC to 100kHz

• Choice of Linearity

- TC9401: 0.02%

- TC9400: 0.05%

- TC9402: 0.25%

• Programmable Scale Factor

Applications

• µP Data Acquisition

• 13-bit Analog-to-Digital Converters

• Analog Data Transmission and Recording

• Phase Locked Loops

• Frequency Meters/Tachometer

• Motor Control

• FM Demodulation

Device Selection Table

Part

Number

TC9400COD 0.05% 14-Pin SOIC

TC9400CPD 0.05% 14-Pin PDIP 0°C to +70°C

TC9400EJD 0.05% 14-Pin CerDIP -40°Cto +85°C

TC9401CPD 0.01% 14-Pin PDIP 0°C to +70°C

TC9401EJD 0.01% 14-Pin CerDIP -40°Cto +85°C

TC9402CPD 0.25% 14-Pin PDIP 0°C to +70°C

TC9402EJD 0.25% 14-Pin CerDIP °C to +85°C

Linearity

(V/F)

Package

(Narrow)

Temperature

Range

0°C to +70°C

General Description

The TC9400/TC9401/TC9402 are low cost voltage-to­frequency ( V/F) converters, utilizing low power CMOS
technology. The converters accept a variable analog
input signal and generatean output pulse train, whose
frequency is linearly proportional to the input voltage.

Thedevicescanalsobeusedashighlyaccuratefre­quency-to-voltage (F/V) converters, accepting virtually
any i nput frequency waveform and providing a linearly
proportional voltageoutput.

A complete V/F or F/V system only requires the addi­tion of two capacitors, three resistors, and reference
voltage.

Package Type

14-Pin Plastic DIP/CERDIP

I

BIAS

ZERO ADJ

V

V

OUT

REF

GND

V

REF

I

BIAS

ZERO ADJ

I

V

SS

V

OUT

REF

GND

V

REF

1

2

I

IN

3

4

5

6

7

TC9400
TC9401
TC9402

SS

14-Pin SOIC

1

2

IN

3

TC9400

4

TC9401
TC9402

5

6

7

NC = No Internal Connection

V

14

DD

13

NC

AMPLIFIER OUT

12

THRESHOLD

11

DETECTOR

FREQ/2 OUT

10

9

OUTPUT COMMON

PULSE FREQ OUT

8

14

V

DD

13

NC

AMPLIFIER OUT

12

THRESHOLD

11

DETECTOR

FREQ/2 OUT

10

9

OUTPUT COMMON

8

PULSE FREQ OUT



2002 Microchip TechnologyInc. DS21483B-page 1

TC9400/9401/9402

g

Functional Block Diagram

Input

Voltage

Integrator
Capacitor

R

IN

I

IN

Reference
Capacitor

I

REF

Reference
Volta

e

Integrator
Op Amp

Threshold
Detector

TC9400

One
Shot

÷2

Pulse Output

Pulse/2 Output

DS21483B-page 2



2002 Microchip TechnologyInc.

TC9400/9401/9402

1.0 ELECTRICAL
CHARACTERISTICS

Absolute Maximum Ratings*

VDD–VSS...........................................................+18V

........................................................................10mA

I

IN

V

OUTMAX–VOUT

V

REF–VSS

Common......................................23V

..........................................................-1.5V

*Stresses above those listed under "Absolute Maximum
Ratings" may cause permanent damage to the device. These
are stress ratings only and functional operation of the device
at these or any other conditions above those indicated in the
operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for
extended periods may affectdevice reliability.

StorageTemperature Range..............-65°C to +150°C

Operating Temperature Range:

C Device ........................................... 0°C to +70°C

E Device.........................................-40°C to +85°C

Package Dissipation (T

≤ 70°C):

A

8-Pin CerDIP..............................................800mW

8-Pin Plastic DIP........................................730mW

8-Pin SOIC. ................................................470mW

TC940X ELECTRICAL SPECIFICATIONS

Electrical Characteristics: VDD=+5V,VSS=-5V,V
specified. T

Parameter Min Typ Max Min Typ Max Min Typ Max Units Test Conditions

= +25°C, unless temperature rangeis specified (-40°C to +85°C for E device, 0°C to +70°CforC device).

A

Voltage-to-Frequency

GND

=0V,V

REF

=-5V,R

=100kΩ, Full Scale = 10kHz, unless otherwise

BIAS

Accuracy TC9400 TC9401 TC9402

Linearity 10kHz — 0.01 0.05 — 0.004 0.01 — 0.05 0.25 %

Linearity 100kHz — 0.1 0.25 — 0.04 0.08 — 0.25 0.5 %

GainTemperature
Drift (Note 1)

GainVariance — ±10 — — ±10 — — ±10 — % of

Zero Offset

(Note 2)

Zero Temperature
Drift (Note 1)

Note 1: Full temperature range; not tested.

2: I

=0.

IN

3: Full temperature range, I
4: I

OUT

5: ThresholdDetect = 5V, Amp Out = 0V, full temperature range.
6: 10Hz to 100kHz; not tested.
7: 5µsec minimum positivepulse width and 0.5µsec minimum negative pulse width.
8: t

R=tF

9: R

≥ 2kΩ, tested @ 10kΩ.

L

10: Full temperature range, V

— ±25 ±40 — ±25 ±40 — ±50 ±100 ppm/°C

— ±10 ±50 — ±10 ±50 — ±20 ±100 mV Correction at Zero

— ±25 ±50 — ±25 ±50 — ±50 ±100 µV/°C VariationinZeroOffset

=10mA.

=10µA.

=20nsec.

OUT

IN

= -0.1V.

Full Scale

Full Scale

Full Scale

Nominal

Output Deviation from
Straight Line Between
Normalized Zero and
FullScale Input

Output Deviation from
Straight Line Between
Normalized Zero Read­ing and Full Scale Input

VariationinGainAdue
to Temperature Change

Variation from Ideal
Accuracy

Adjustfor ZeroOutput
whenInputis Zero

DuetoTemperature
Change



2002 Microchip TechnologyInc. DS21483B-page 3

TC9400/9401/9402

TC940X ELECTRICAL SPECIFICATIONS (CONTINUED)

Electrical Characteristics: VDD=+5V,VSS=-5V,V

specified. T

= +25°C, unless temperature rangeis specified (-40°C to +85°C for E device, 0°C to +70°CforC device).

A

Parameter Min Typ Max Min Typ Max Min Typ Max Units Test Conditions

Analog Input

I

Full Scale — 10 — — 10 — — 10 — µA Full Scale Analog Input

IN

Over Range — — 50 — — 50 — — 50 µA Over RangeCurrent

I

IN

Response Time — 2 — — 2 — — 2 — Cycle Settling Time to 0.1%

Digital Section TC9400 TC9401 TC9402

V

SAT@IOL

V

OUTMAX–VOUT

Common (Note 4)

PulseFrequency

= 10mA — 0.2 0.4 — 0.2 0.4 — 0.2 0.4 V Logic "0" Output

— — 18 — — 18 — — 18 V VoltageRange

—3——3——3 —µsec

OutputWidth

Frequency-to-Voltage

GND

=0V,V

REF

=-5V,R

=100kΩ, Full Scale = 10kHz, unless otherwise

BIAS

Current to achieve
Specified Accuracy

Full Scale

Voltage (Note 3)

Between Output and
Common

Supply Current

Quiescent

I

DD

(Note 5)

— 1.5 6 — 1.5 6 — 3 10 mA Current Required from

Positive Supply during
Operation

Quiescent

I

SS

(Note 5)

— -1.5 -6 — -1.5 -6 — -3 -10 mA Current Required from

Negative Supplyduring
Operation

Supply 4 — 7.5 4 — 7.5 4 — 7.5 V Operating Range of

V

DD

Supply -4 — -7.5 -4 — -7.5 -4 — -7.5 V Operating Range of

V

SS

Positive Supply

Negative Supply

Reference Voltage

V

REF–VSS

-2.5 — — -2.5 — — -2.5 — — V Range of Voltage
Reference Input

Accuracy

Non-Linearity

(Note 10)

— 0.02 0.05 — 0.01 0.02 — 0.05 0.25 %

Full Scale

Deviation from ideal
Transfer Function as a
Percentage Full Scale
Voltage

InputFrequency
Range

10 — 100k 10 — 100k 10 — 100k Hz Frequency Range for

Specified Non-Linearity

(Notes 7 and 8)
Note 1: Full temperature range; not tested.

=0.

2: I

IN

3: Full temperature range, I
4: I
5: ThresholdDetect = 5V, Amp Out = 0V, full temperature range.

OUT

=10µA.

OUT

=10mA.

6: 10Hz to 100kHz; not tested.
7: 5µsec minimum positivepulse width and 0.5µsec minimum negative pulse width.
8: t
9: R
10: Full temperature range, V

=20nsec.

R=tF

≥ 2kΩ, tested @ 10kΩ.

L

= -0.1V.

IN

DS21483B-page 4



2002 Microchip TechnologyInc.

TC9400/9401/9402

TC940X ELECTRICAL SPECIFICATIONS (CONTINUED)

Electrical Characteristics: VDD=+5V,VSS=-5V,V

specified. T

= +25°C, unless temperature rangeis specified (-40°C to +85°C for E device, 0°C to +70°CforC device).

A

Parameter Min Typ Max Min Typ Max Min Typ Max Units Test Conditions

Frequency Input

Positive Excursion 0.4 — V

0.4 — V

DD

Negative Excursion -0.4 -2 -0.4 — -2 -0.4 — -2 V VoltageRequired to

MinimumPositive

—5——5——5 —µsec Time between

Pulse Width

(Note 8)

MinimumNegative

— 0.5 — — 0.5 — — 0.5 — µsec Time Between

Pulse Width

(Note 8)

Input Impedance — 10 — — 10 — — 10 MΩ

Analog Outputs TC9400 TC9401 TC9402

OutputVoltage

(Note 9)

—V

DD

–1 — — VDD–1 — — VDD– 1 — V Voltage Range of Op

OutputLoading 2 — — 2 — — 2 — — kΩ Resistive Loadingat

Supply Current TC9400 TC9401 TC9402

Quiescent

I

DD

(Note 10)

I

Quiescent

SS

— 1.5 6 — 1.5 6 — 3 10 mA Current Requiredfrom

— -1.5 -6 -1.5 -6 — -3 -10 mA Current Required from

(Note 10)

Supply 4 — 7.5 4 — 7.5 4 — 7.5 V Operating Range of

V

DD

Supply -4 — -7.5 -4 — -7.5 -4 — -7.5 V Operating Range of

V

SS

Reference Voltage

V

REF–VSS

-2.5 — — -2.5 — — -2.5 — — V Range of Voltage

Note 1: Full temperature range; not tested.

=0.

2: I

IN

3: Full temperature range, I
4: I

OUT

=10µA.

OUT

=10mA.

5: ThresholdDetect = 5V, Amp Out = 0V, full temperature range.
6: 10Hz to 100kHz; not tested.
7: 5µsec minimum positivepulse width and 0.5µsec minimum negative pulse width.
8: t
9: R
10: Full temperature range, V

=20nsec.

R=tF

≥ 2kΩ, tested @ 10kΩ.

L

= -0.1V.

IN

GND

=0V,V

=-5V,R

REF

0.4 — V

DD

=100kΩ, Full Scale = 10kHz, unless otherwise

BIAS

DD

V VoltageRequired to

Turn Threshold
Detector On

Turn Threshold
Detector Off

Threshold Crossings

Threshold Crossings

Amp Outputfor Speci­fied Non-Linearity

Output of Op Amp

Positive Supply During
Operation

Negative Supply
During Operation

Positive Supply

Negative Supply

Reference Input



2002 Microchip TechnologyInc. DS21483B-page 5

TC9400/9401/9402

2.0 PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 2-1.

TABLE 2-1: PIN F UNCTION TABLE

Pin No.

14-Pin PDIP/CERDIP

14-Pin SOIC (Narrow)

1I
2 ZERO ADJ Low f requency adjustment input.
3I
4V
5V
6 GND Analog ground.
7V
8 PULSE FREQ

9OUTPUT

10 FREQ/2 OUT This open drain output is a square wave at one-half the frequency of the pulse output

11 THRESHOLD

12 AMPLIFIEROUT Output of the integrator amplifier.
13 NC No internal connection.
14 V

Symbol Description

BIAS

IN

SS

OUT Reference capacitor connection.

REF

REF

OUT

COMMON

DETECTOR

DD

This pin sets bias current in the TC9400. Connect to VSSthrougha 100kΩ resistor.

Inputcurrent connectionfor theV/F converter.
Negative power supply voltage connection, typically -5V.

Voltage reference input, typically -5V.
Frequency output. This opendrain output will pulse LOW each timetheFreq.

Threshold Detectorlimitis reached. The pulse rate is proportional to input voltage.
Sourceconnection for the open drain output FETs.

(Pin 8). Output transitions of this pin occur on the rising edge of Pin8.
Inputto the ThresholdDetector.This pin is the frequency input duringF/V operation.

Positive power supply connection, typically +5V.

DS21483B-page 6



2002 Microchip TechnologyInc.

TC9400/9401/9402

3.0 DETAILED DESCRIPTION

3.1 Voltage-to-Frequency (V/F) Circuit
Description

The TC9400 V/F converter operateson the principalof
charge balancing. The operationof the TC9400 is eas­ilyunderstoodby referringto Figure 3-1.The input volt­age (V
resistor. This current is then converted to a charge on
the integrating capacitor and shows up as a linearly
decreasing voltage at the output of the Op Amp. The
lower limit of the output swing is set by the threshold
detector, which causes the reference voltage to be
appliedtothe referencecapacitorfora time period long
enough to charge the capacitor to the reference volt­age. This action reduces the charge on the integrating
capacitorby a fixed amount (q = C
the Op Amp output to step up a finite amount.

At the end of the charging period, C
This dissipates the charge stored on the reference
capacitor, so that when the output again crosses zero,
the system is ready to recycle. In this manner, the con­tinued discharging of the integrating capacitor by the

FIGURE 3-1: 10Hz TO 10kHz V/F CONVERTER

) is converted to a current (IIN) by the input

IN

REFxVREF

REF

Threshold

11

Detect

12

AMP OUT

),causing

is shorted out.

-3V

Threshold

Detector

Self-

Start

input is balanced out by fixed charges from the refer­ence voltage. As the input voltage is increased, the
number of reference pulses required to maintain bal­ance increases, which causes the output frequency to
alsoincrease.Sinceeachcharge incrementisfixed,the

increasein frequency with voltage is linear. In addition,

the accuracy of the output pulse width does not directly
affect the linearity of the V/F.The pulse must simply be
long enough f or full charge transferto take place.

The TC9400 containsa "self-start" circuit to ensure the
V/F converter always operates properlywhen power is
first applied. In the event that, during power-on, the Op
Amp output is below the threshold and C

REF

is already
charged, a positive voltage step will not occur. The Op
Ampoutputwillcontinuetodecreaseuntil it crosses the

-3.0V threshold of the "self-start" comparator. When
this happens, an internal resistor i s connected to the
Op Amp input, which forces the output to go positive
until the TC9400 is in its Normal Operating mode.

The TC9400 utilizes low power CMOS pr ocessing for
low input bias and offset currents, with very low power
dissipation. The open drain N-channel output FETs
provide high voltage and high current sink capability.

+5V

V

DD

3µsec

Delay

14

÷2

F

F

OUT

Output

Common

OUT

+

5V

R

L

10kΩ

8

+

5V

R

L

10

9

10kΩ

/2

OUT

V

REF

5

R

BIAS

100kΩ

20kΩ

60pF

–

Op Amp

+

I

BIAS

1

V

SS

4

Reference Voltage

(Typically -5V)

-5V

V

7

REF

TC9400
TC9401
TC9402

GND

6

C

INT

820pF

R

50kΩ

IN

1MΩ

+5V

-5V

Offset
Adjust

INPUT

V

IN

0V –10V



2002 Microchip TechnologyInc. DS21483B-page 7

510kΩ

C

REF

180pF

10kΩ

I

IN

3

Zero Adjust

2

12pF

TC9400/9401/9402

3.2 Voltage-to-Time Measurements

The TC9400 output can be measured in the time
domain as well as the frequency domain. Some micro­computers,forexample,haveextensive timing capabil­ity, but limited counter capability. Also, the response
time of a time domain measurement is only the period
between two output pulses, while the frequency mea­surement must accumulate pulses during the entire
counter time-base period.

Time measurements can be made from either the
TC9400's PULSE FREQ OUT output, or f rom the
FREQ/2 OUT output. The FREQ/2 OUT output
changes state on the rising edge of PULSE FREQ
OUT,so FREQ/2 OUTis a symmetricalsquarewaveat
one-half the pulse output frequency. Timing measure­ments can, t herefore, be made between successive
PULSE FREQ OUT pulses, or while FREQ/2 OUT is
high (or low).

4.0 PIN FUNCTIONS

4.1 Threshold Detector Input

In the V/F mode, this input is connected to the AMPLI­FIER OUT output (Pin 12) and triggers a 3µsec pulse
when the input voltage passes through its threshold. In
the F/V mode, the input frequency is applied to this
input.

The nominal threshold of the detector is half way
betweenthepower supplies,or(V

DD+VSS

The TC9400's c harge balancing V/F technique is not
dependent on a precision comparator threshold,
because the threshold only sets the lower limit of the
Op Amp output. The Op Amp's peak-to-peak output
swing, which determines the frequency, is only
influenced by external capacitors and by V

4.2 Pulse Freq O ut

This output is an open drain N-channel FET, which pro­vides a pulse waveform whose frequency is propor­tional to the input voltage. This output requires a pull­up resistor and interfaces directly with MOS, CMOS,
and TTL logic (see Figure 4-1).

)/2±400mV.

.

REF

FIGURE 4-1: OUTPUT WAVEFORM S

3µsec

F

OUT

F

/2

OUT

Amp Out

Notes: 1. To adjust F

2. To adjust F

3. To increase F

4. For high performance applications, use high stability components for R
resistors and glass capacitors). Also, separate output ground (Pin 9) from input ground (Pin 6).

Typ.

1/f

, set VIN = 10mV and adjust the 50kΩ offset for 10Hz output.

MIN

, set VIN = 10V and adjust R

MAX

to 100kHz, change C

OUTMAX

or V

IN

to 2pF and C

REF

for 10kHz output.

REF

INT

to 75pF.

C

REF

REF

C

INT

V

0V

, C

, V

IN

REF

REF

(metal film

DS21483B-page 8



2002 Microchip TechnologyInc.

TC9400/9401/9402

4.3 Freq/2 Out

This output is an open drain N-channel FET, which pro­vides a square wave one-half the frequency of the
pulse frequency output. The FREQ/2 OUT output will
change state on the rising edge of PULSE FREQ OUT.
This output requires a pull-up resistor and interfaces
directly with MOS, CMOS, and TTL logic.

4.4 Output Common

The sources of both the FREQ/2 OUT and the PULSE
FREQ OUT are connected to this pin. An output level
swing from the drain voltage to ground, or to the V
supply, may be obtained by connecting this pin to the
appropriate point.

4.5 R

An external resistor, connected to VSS, sets the bias
pointfor the TC9400. Specifications for the TC9400 are
based on R
noted.

Increasing the maximum frequency of the TC9400
beyond 100kHz is limited by the pulse width of t he
pulse output (typically 3µsec). Reducing R
decrease the pulse width and increase the maximum
operating frequency, but linearity errors will also
increase. R
typically produce a maximum full scale frequency of
500kHz.

BIAS

= 100kΩ ±10%, unless otherwise

BIAS

can be reduced to 20kΩ,whichwill

BIAS

BIAS

SS

will

4.6 Amplifier Out

This pin is the outputstage of the operationalamplifier.
During V/F operation, a negative going ramp signal is
available at this pin. In the F/V mode, a voltage
proportionalto the frequency input is generated.

4.8 I

The inverting input of the operational amplifier and the
summing junctionwhenconnectedintheV/F mode. An
input current of 10µA is specified, but an over range
current up to 50µA can be used without detrimental
effecttothecircuitoperation. I
junction of an operational amplifier. Voltage sources
cannot be attached directly, but must be buffered by
external resistors.

4.9 V

A reference voltage from either a precision source, or
the V
TC9400 is dependent on the voltage regulation and
temperature characteristics of the reference circuitry.

Since the TC9400 is a charge balancing V/F converter,
the reference current will be equal to the input current.
For this reason, the DC impedance of the reference
voltagesource must be kept lowenough to preventlin­earity errors. For linearity of 0.01%,a reference imped­ance of 200W or less is recommended.A 0.1µFbypass
capacitorshould be connected from V

4.10 V

The charging current for C
pin. When the Op Amp output reaches the threshold
level, this pin is internally connected to the reference
voltageand acharge,equaltoV
fromtheintegratorcapacitor.After about3µsec, this pin
is internally connected to the summing junction of the
OpAmptodischargeC
ing ensures that t he reference voltage is not directly
applied to the summing junction.

IN

connectsthesumming

IN

REF

supply is applied t o this pin. Accuracy of the

SS

to ground.

REF

Out

REF

is supplied through this

REF

REFxCREF

. Break-before-makeswitch-

REF

, is removed

4.7 Zero Adjust

This pin is the non-inverting input of the operational
amplifier. The low frequencyset point is determined by
adjusting the voltage at this pin.



2002 Microchip TechnologyInc. DS21483B-page 9

TC9400/9401/9402

5.0 VOLTAGE-TO-FREQUENCY
(V/F) CONVERTER DESIGN
INFORMATION

5.1 Input/Output Relationships

The output frequency (F
input voltage (V

) by the transfer equation:

IN

EQUATION 5-1:

Frequency Out =

5.2 External Component Selection

5.2.1 R

The value of this component is chosen to give a full
scale input current of approximately 10µA:

EQUATION 5-2:

EQUATION 5-3:

Note that the value is an approximation and the exact
relationshipi s definedby the transferequation.In prac­tice, the value of R
obtain full scale frequency at V
Section 5.3, Adjustment Procedure). Metal film resis­tors with 1% tolerance or better are recommended for
high accuracy applications because of their thermal
stability and low noise generation.

5.2.2 C

The exact value is not cr itical but is related to C
the relationship:

Improved stability and linearity are obtained when
C

≤ 4C

INT

although mica and ceramic devices can be used in
applications wher e their temperature limits are not
exceeded. Locate as close as possible to Pins 12
and 13.

5.2.3 C

Theexactvalueisnotcriticalandmaybeusedtotrim
the full scale frequency (see Section 7.1, Input/Output
Relationships). Glass film or air trimmer capacitors are
recommended because of their stability and low leak­age. Locate as close as possible t o Pins 5 and 3 (see
Figure 5-1).

IN

≅

R

IN

R

IN

IN

INT

3C

REF

. Low leakage types are recommended,

REF

REF

) is related to the analog

OUT

V

R

FULLSCALE

V

IN

IN

,x

IN

(V

REF

1

)(V

REF

)

10µA

10V

≅ =1MΩ

10µA

typicallywouldbetrimmedto

full scale (see

IN

REF

≤ C

≤ 10C

INT

REF

by

FIGURE 5-1: RECOMMENDED

C

VS. V

500

400

300

(pF) +12pF

200

REF

C

100

0

-1

5.2.4 VDD,V

REF

10kHz

100kHz

-2 -3 -4 -5 -6 -7
V

SS

REF

(V)

REF

V

DD

V

SS

R

IN

V

IN

T

A

= +5V

= -5V
= 1MΩ
= +10V

= +25°C

Power supplies of ±5V are recommended. For high
accuracy requirements,0.05% line and load regulation
and 0.1µF disc decouplingcapacitors,locatednearthe
pins, are recommended.

5.3 Adjustment Procedure

Figure 3-1 shows a circuit for trimming the zero loca­tion. Full scalemay be trimmed by adjustingR
or C

. Recommended procedure for a 10kHz full

REF

IN,VREF

scale frequency is as follows:

1. Set V

to 10mV and trim the zero adjust circuit

IN

to obtain a 10Hz output frequency.

2. SetV

to10V andtrim eitherRIN,V

IN

REF

,orC

REF

to obtain a 10kHz output frequency.

If adjustments are performed in this order,thereshould
be no interaction and they should not have to be
repeated.

5.4 Improved Single Supply V/F
Converter Operation

A TC9400, which operates from a single12to15V vari­able power source, is shown in Figure 5-2. This circuit
uses two Zener diodes to set stable biasing levels for
the TC9400. The Zener diodes also provide the refer­ence voltage, so the output impedance and tempera­ture coefficient of the Zeners will directly affect power
supply rejection and temperature performance. Full
scaleadjustmentisaccomplished by trimmingtheinput
current. Trimming the reference voltage is not recom­mended for high accuracy applications unless an
Op Amp is used as a buffer, because the TC9400
requires a low impedance reference (see Section 4.9,
V

pin description, for more information).

REF

The circuit of Figure 5-2 will directly interface with
CMOS logic operatingat 12V to 15V. TTL or 5V CMOS
logic can be accommodated by connecting the output
pull-up resistors to the +5V supply. An optoisolator can
also be used if an isolated output is required; also, see
Figure 5-3.

,

DS21483B-page 10



2002 Microchip TechnologyInc.

FIGURE 5-2: VOLTAGE TO FREQUENCY

y

1µF

R

Gain

3

100k

Offset

R

100k

R

91k

Rp

20k

4

5

D

2

5.1VZ

D

1

5.1VZ

Analog Ground

C

INT

910k

910k

Input

Voltage

(0 to 10V)

R

1

R

2

1.2k

0.1µ

100k

C

REF

TC9400/9401/9402

+12 to +15V

14

V

DD

Threshold

11

Detect

12

Amp Out

5

C

I

3

IN

Zero Adjust

2

6

GND

7

V

1

I

BIAS

REF

TC9400

REF

V

SS

4

F

OUT

F

OUT

Output

Common

/2

10k 10k

8

10

9

Digital
Ground

Output
Frequenc

Component Selection

F/S FREQ.

1kHz

10kHz

100kHz

C

REF

2200pF

180pF

27pF

C

INT

4700pF

470pF

75pF

FIGURE 5-3: FIXED VOLTAGE - SINGLE SUPPLY OPERATION

V+ = 8V to 15V (Fixed)

R

V

IN

0V–10V

Gain

Adjust

Offset
Adjust

R

1MΩ

2

V

0.9
5V

R

1

8.2
kΩ

2

kΩ

0.2
R

1

820

IN

pF

2

2
6

0.01
µF

7

11

0.01
µF

12

5

180
pF

3

I

IN

100kΩ

14

TC9400

V

REF

I

IN

149

8

10

10kΩ

10kΩ

F

F

OUT

OUT

/2

R

V+

10V
12V

1.4MΩ

15V



2002 Microchip TechnologyInc. DS21483B-page 11

1

1MΩ

2MΩ

R

2

10kΩ
14kΩ
20kΩ

F

OUT

I

IN

= I

IN

(V

IN

=

R

1

–

(V

V7) (C

2

– V2) (V+ – V2)

+

IN

(0.9R

REF

+ 0.2R1)

1

)

TC9400/9401/9402

(a)

y

6.0 FREQUENCY-TO-VOLTAGE
(F/V) CIRCUIT DESCRIPTION

Whenused as an F/V converter,theTC9400generates
an output voltage linearly proportional to the input
frequency waveform.

Each zero crossing at the threshold detector's input
causes a precise amount of charge (q = C
to be dispensed into the Op Amp's summing junction.
This charge, in turn, flows through the feedback resis­tor, generating voltage pulses at the output of the Op
Amp. A capacitor (C

)acrossR

INT

averages these

INT

pulses into a DC voltage, which is linearly proportional
to the input frequency.

7.0 F/V CONVERTER DESIGN
INFORMATION

7.1 Input/Output Relationships

The output voltage is related to the input frequency
(F

) by the transfer equation:

IN

EQUATION 7-1:

V

=[V

OUT

The r esponse time t o a change in FINis equal to (R
C

). The amount of ripple on V

INT

proportionalto C

REFCREFRINT]FIN

and the input frequency.

INT

OUT

∞ V

REF

REF

INT

is inversely

canbe increasedto lowertheripple. Valuesof 1µF

C

INT

to 100µF are perfectlyacceptable for low frequencies.
When the TC9400 is used in the Single Supply mode,

V

isdefinedasthevoltagedifference betweenPin 7

REF

and Pin 2.

7.2 Input Voltage Levels

)

The input frequency is applied to the Threshold Detec­tor input (Pin 11). As discussed in the V/F circuit section
of this data sheet, the threshold of Pin 11 is approxi­mately (V

DD+VSS

rangeextends fromV

)/2 ±400mV. Pin 11's input voltage

to about 2.5V below the thresh-

DD

old. If the voltage on Pin 11 goes more than 2.5 volts
below the threshold, t he V/F mode start-up comparator
will turn on and corrupt the output voltage. The Thresh­old Detector input has about 200mV of hysteresis.

In ±5V applications, the input voltage levels for the
TC9400 are ±400mV, minimum. I f the frequency
source being measured is unipolar, such as TTL or
CMOS operating from a +5V source, then an AC cou­pled level shifter should be used. One such circuit is
showninFigure7-1(a).

The level shifter circuit in Figure 7-1(b) can be used i n
single supply F/V applications. The resistor divider
ensures that the input threshold will track the supply
voltages. The diode clamp prevents the input f rom
going far enough in the negativedirection to turn on the
start-up comparator. The diode's forward voltage
decreases by 2.1mV/°C, so for high ambient tempera­ture operation, two diodes in series are recommended;
also, see Figure 7-2.

FIGURE 7-1: FREQUENCY INPUT LEVEL SHIFTER

+5V

14

V

DD

TC9400

0.01µF

Frequency

Input

+5V

0V

33k

IN914

±5V Suppl

11

1.0M

DET

GND

V

64

-5V

SS

Frequency

Input

+5V

0V

33k

0.01µF

10k

IN914

0.1µF

1.0M

10k

(b) Single Supply

11

+8V to +5V

V

TC9400

DET

DD

V

14

SS

4

DS21483B-page 12



2002 Microchip TechnologyInc.

FIGURE 7-2: F/V SINGLE SUPPLY F/V CONVERTER

10k

6

GND

TC9400/9401/9402

V+ = 10V to 15V

14

V

DD

Frequency

Input

500k

.01µF

IN914

0.1µF

10k

V+

1.0k

11

1.0M

1.0k

6.2V

100k

Offset
Adjust

33k

Note: The output is referenced to Pin 6, which is at 6.2V (Vz). For frequency meter applications,

a 1mA meter with a series scaling resistor can be placed across Pins 6 and 12.

0.01µF

2

TC9400

Zero
Adjust

DET

I

BIAS

100k

V

REF

V

REF

Amp Out

V

7

OUT

GND

SS

4

5

47pF

3

I

IN

1M

12

6

.001µF

V

OUT

7.3 Input Buffer

F

and F

OUT

ever, these outputs may be useful for some applica­tions, suchas a buffertofeed additionalcircuitry. Then,
F

will follow the input frequency waveform, except

OUT

that F

OUT

F

/2 will be square wave with a frequency of

OUT

one-half F
If these outputs are not used, Pins 8, 9 and 10 should be

connected to ground (see Figure 7-3 and Figure 7-4).



2002 Microchip TechnologyInc. DS21483B-page 13

/2 are not used in the F/V mode. How-

OUT

will go high 3µsec after FINgoes high;

.

OUT

FIGURE 7-3: F/V DIGITAL OUTPUTS

0.5µsec
Min

F

Input

F

OUT

OUT

/2

5.0µsec
Min

Delay = 3µsec

TC9400/9401/9402

T

FIGURE 7-4: DC - 10kHz CO N V ER TER

F

-5V

IN

2kΩ

See

Figure 7-1:

"Frequency
Input Level

Shifter"

Offset

Adjust

+5V

100kΩ

2.2kΩ

Threshold
Detect

Zero Adjust

2

TC9400A
TC9401A
TC9402A

11

Threshold
Detector

10kΩ

V

SS

I

BIAS

14

3µsec

Delay

7

+5V

14

V

DD

V

REF

V

REF

(Typically -5V)

42

–

Op
Amp
+

Common

12pF

60pF

GND

6

F

OUT

Output

F

OUT

V

REF

OUT

I

Amp
Out

V+

/2

10

V+

9

*

8

*Optional/If
Buffer is Needed

5

IN

3

R
1MΩ

12

*

*

C

REF

56pF

INT

+

C

INT

1000pF

V

OUT

7.4 Output Filtering

The output of the TC9400 has a sawtooth ripple super­imposed on a DC level. The ripplewill be rejected if the
TC9400outputisconvertedto a digital value by aninte­gratinganalog-to-digitalconverter, suchas the TC7107
or TC7109. The ripple can also be reduced by increas­ing the value of the integrating capacitor,although this
will reduce the responsetime of the F/V converter.

ThesawtoothrippleontheoutputofanF/Vcanbe
eliminated without affecting the F/V's response time by
using the circuit in Figure 7-5. The circuit is a capaci­tance multiplier, where the output coupling capacitor is
multipliedby the AC gainof the Op Am p. A moderately
fast Op Amp, such as the TL071, should be used.

FIGURE 7-5: RIPPLE FILTER

OUT

5

47pF

3

I

IN

.001µF

1M

12

200

.01µF

1M

2

–

3

+

V

REF

TC9400

AMP OUT

GND

6

1M

0.1µF

+5

V

6

OU

TL071

7

4

-5

DS21483B-page 14



2002 Microchip TechnologyInc.

TC9400/9401/9402

0

8.0 F/V POWER-ON RESET

In F/V mode, the TC9400 output voltage will occasion­ally be at its maximum value when power i s first
applied. This condition remains until the first pulse is
applied to F
cations,thisis not a problembecause proper operation
begins as soon as the frequency input is applied.

FIGURE 8-1: POWER-ON OPERATION/RESET

F

IN

. In most f requency measurement appli-

IN

(a) (b)

14

1000pF

1kΩ

11

Threshold
Detector

TC9400

V

DD

V

DD

100kΩ

1µF

In some cases, however, the TC9400 output must be
zero at power-on without a frequency input. In such
cases, a capacitor connected from Pin 11 to V

DD

will
usuallybe sufficient to pulse t he TC9400 and providea
Power-on Reset (see Figure 8-1 (a) and (b)). Where
predictablepower-on operation is critical, a more com­plicated circuit, such as Figure 8-1 (b), may be
required.

12516

Q

6

F

IN

To TC940

3

4

V

CLRA

A

B R C

CC

CD4538

V

SS

8



2002 Microchip TechnologyInc. DS21483B-page 15

TC9400/9401/9402

(

)

9.0 PACKAGE INFORMATION

9.1 Package Marking Information

Package marking data is not available at t his time.

9.2 Taping Form

Component Taping Orientation for 14-Pin SOIC (Narrow) Devices

PIN 1

Standard Reel Component Orientation
for TR Suffix Device

Carrier Tape, Reel Size, and Number of Components Per Reel

Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size

14-Pin SOIC (N) 12 mm 8 mm 2500 13 in

User Direction of Feed

W

P

9.3 Package Dimensions

14-Pin CDIP (Narrow)

.098 (2.49) MAX. .030 (0.76) MIN.

.780 (19.81)
.740 (18.80)

.200 (5.08)
.160 (4.06)

.200 (5.08)
.125 (3.18)

.110 (2.79)
.090 (2.29)

.065 (1.65)
.045

1.14

.020 (0.51)
.016 (0.41)

PIN 1

.300 (7.62)
.230 (5.84)

.040 (1.02)
.020 (0.51)

.150 (3.81)

MIN.

.015 (0.38)
.008 (0.20)

.320 (8.13)
.290 (7.37)

3° MIN.

.400 (10.16)

.320 (8.13)

Dimensions: inches (mm)

DS21483B-page 16



2002 Microchip TechnologyInc.

9.3 Package Dimensions (Continued)

14-Pin PDIP (Narrow)

TC9400/9401/9402

PIN 1

.260 (6.60)
.240 (6.10)

.770 (19.56)
.745 (18.92)

.200 (5.08)
.140 (3.56)

.150 (3.81)
.115 (2.92)

.110 (2.79)
.090 (2.29)

.070 (1.78)
.045 (1.14)

14-Pin SOIC (Narrow)

PIN 1

.157 (3.99)
.150 (3.81)

.022 (0.56)
.015 (0.38)

.244 (6.20)
.228 (5.79)

.040 (1.02)
.020 (0.51)

.015 (0.38)
.008 (0.20)

.310 (7.87)
.290 (7.37)

3° MIN.

.400 (10.16)

.310 (7.87)

Dimensions: inches (mm)

.050 (1.27) TYP.

.344 (8.74)
.337 (8.56)

.069 (1.75)
.053 (1.35)

.018 (0.46)
.014 (0.36)



2002 Microchip TechnologyInc. DS21483B-page 17

.010 (0.25)
.004 (0.10)

8° MAX.

.050 (1.27)
.016 (0.40)

Dimensions: inches (mm)

.010 (0.25)
.007 (0.18)

TC9400/9401/9402

SALES AND SUPPORT

Data Sheets

Products supportedby a preliminary Data Sheet may have an errata sheet describing minor operational differences and recom­mendedworkarounds.To determine if an errata sheet exists for a particulardevice, please contactoneof the following:

1. Your local Microchip sales office

2. The Microchip Corporate LiteratureCenter U.S. FAX:[phone]

3. The Microchip Worldwide Site (www.microchip.com)
Pleasespecify which device, revision of silicon and Data Sheet (includeLiterature#) you are using.

New Customer Notification System

Register on our web site (www.microchip.com/cn) to receive the most current information on our products.

DS21483B-page 18



2002 Microchip TechnologyInc.

TC9400/9401/9402

Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical com­ponents in life support systems is not authorized except with
express written approval by Microchip. No licenses are con­veyed, implicitly or otherwise, under any intellectual property
rights.

Trademarks

The Microchip name and logo, the Microchip logo, FilterLab,
K

EELOQ,microID,MPLAB,PIC,PICmicro,PICMASTER,

PICSTART, PRO MATE, SEEVAL and The Embedded Control

SolutionsCompany areregiste red trademarksof MicrochipTech­nologyIncorp or ated in the U.S.A. and other countries .

dsPIC, ECONOMONITOR, FanSense, Fle xRO M , fuzzyLA B,
In-Circuit Serial Programming, ICSP, ICEPIC, microPort,
Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM,
MXDEV, PICC, PICDEM, PICDEM .n et , rfPIC, Select Mode
and TotalEndurancearetrademarksofMicrochipTechnology
Incorporated in the U.S.A.

Serialized Quick Turn Programming (SQTP) is a service mark
of Microchip TechnologyIncorporated in t he U.S.A.

All other trademarks mentioned herein are property of their
respective companies.

© 2002, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.

Printed on recycled paper.

Microchip received QS-9000 quality system
certification for its worldwide headquarters,
design and wafer fabrication facilities in
Chandler and Tempe, Arizona in July 1999
and Mountain View,California in March 2002.
The Company’s quality system processes and
procedures are QS-9000 compliant for its

®

PICmicro
devices, Serial EEPROMs, microperipherals,
non-volatile memory and analog products. In
addition, Microchip’s quality system for the
design and manufacture of development
systemsisISO 9001certified.



2002 Microchip TechnologyInc. DS21483B-page 19

8-bit MCUs, KEELOQ®code hopping

WORLDWIDE SALES AND SERVICE

AMERICAS

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03/01/02

DS21483B-page 20

*DS21483B*



2002 Microchip Technology Inc.