Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - V/F converters VFC 4 MHz PDIP 14

FEATURES

D HIGH-FREQUENCY OPERATION:

4MHz FS max

D EXCELLENT LINEARITY:

±0.02% typ at 2MHz

D PRECISION 5V REFERENCE

D DISABLE PIN

D LOW JITTER

APPLICATIONS

D INTEGRATING A/D CONVERSION

D PROCESS CONTROL

D VOLTAGE ISOLATION

D VOLTAGE-CONTROLLED OSCILLATOR

D FM TELEMETRY

DESCRIPTION

The VFC110 voltage-to-frequency converter is a

third-generation VFC offering improved features and

performance. These include higher frequency operation,

an onboard precision 5V reference, and a Disable

function.

The precision 5V reference can be used for offsetting the

VFC transfer function, as well as exciting transducers or

bridges. The Enable pin allows several VFCs’ outputs to

be paralleled, multiplexed, or simply to shut off the VFC.

The open-collector frequency output is TTL-/

CMOS-compatible. The output may be isolated by using

an opto-coupler or transformer.

Internal input resistor, one-shot and integrator capacitors

simplify applications circuits. These components are

trimmed for a full-scale output frequency of 4MHz at 10V

input. No additional components are required for many

applications.

The VFC110 is packaged in a plastic 14-pin DIP. Industrial

and military temperature range gradeouts are available.

Input Common

112

OUT

Comparator

One−Shot

REF

−

Analog Ground

413

Digital Ground

OUT

Enable

VFC110

SBVS021A − OCTOBER 1988 − REVISED APRIL 2007

High-Frequency

VOLTAGE-TO-FREQUENCY CONVERTER

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          

 !     !   

www.ti.com

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments

semiconductor products and disclaimers thereto appears at the end of this data sheet.

PowerPAD is a trademark of Texas Instruments Incorporated. All other trademarks are the property of their respective owners.

Summary of content (12 pages)

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VFC110 SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 High-Frequency VOLTAGE-TO-FREQUENCY CONVERTER FEATURES DESCRIPTION D HIGH-FREQUENCY OPERATION: D The VFC110 voltage-to-frequency converter is a third-generation VFC offering improved features and performance. These include higher frequency operation, an onboard precision 5V reference, and a Disable function. 4MHz FS max EXCELLENT LINEARITY: ±0.
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"# $$% www.ti.com SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 ABSOLUTE MAXIMUM RATINGS(1) Power Supply Voltages (+VS to −VS) . . . . . . . . . . . . . . . . . . . . . 40V fOUT Sink Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA Comparator In Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . −5V to +VS Enable Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +VS to −VS Integrator Common-Mode Voltage . . . . . . . . . . . . . −1.5V to +1.
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"# $$% www.ti.com SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 ELECTRICAL CHARACTERISTICS At TA = +25°C and VS = ±15V, unless otherwise noted.
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"# $$% www.ti.com SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 TYPICAL CHARACTERISTICS At TA = +25°C and VS = ±15V, unless otherwise noted.
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"# $$% www.ti.com SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 TYPICAL CHARACTERISTICS (continued) At TA = +25°C and VS = ±15V, unless otherwise noted. NONLINEARITY vs FULL−SCALE FREQUENCY NONLINEARITY vs INPUT VOLTAGE 1 0.6 0.01 0.4 fFS = 4MHz 0.2 0 0 −0.2 −0.01 −0.4 fFS = 1MHz −0.6 −0.02 −0.8 −1.0 0 1 2 3 4 5 6 Input Voltage (V) 7 8 9 10 Typical Nonlinearity (% of FSR) 0.8 0.02 4MHz FS Linearity Error (% of FSR) 1MHz FS Linearity Error (% of FSR) 1.0 0.1 0.01 0.
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"# $$% www.ti.com SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 connected to logic ground. The one-shot connection (pin 6) is not short-circuit protected. Short-circuits to ground may damage the device. OPERATION Figure 1 shows the connections required for operation at a full-scale output frequency of 4MHz. Only power supply bypass capacitors and an output pull-up resistor, RPU, are required for this mode of operation. A 0V to 10V input voltage produces a 0Hz to 4MHz output frequency.
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"# $$% www.ti.com SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 Table 1. Component Selection Table FULL-SCALE FREQUENCY, fFS chosen for the pull-up resistor may depend on the full-scale frequency and capacitance on the output line. Excessive capacitance on fOUT will cause a slow, rounded rising edge at the end of an output pulse. This effect can be minimized by using a pull-up resistor which sets the output current to its maximum of 8mA. The logic power supply can be any positive voltage up to +VS.
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"# $$% www.ti.com SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 PRINCIPLE OF OPERATION The oscillation is regulated by the balance of current (or charge) between the input current and the time-averaged reset current. The equation of current balance is: The VFC110 uses a charge-balance technique to achieve high accuracy. The heart of this technique is an analog integrator formed by the integrator op amp, feedback capacitor CINT, and input resistor RIN.
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"# $$% www.ti.com SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 MEASURING THE OUTPUT FREQUENCY characteristic curve Frequency Count Repeatability vs Counter Gate Time shows the effect of noise as the counter gate time is varied. It shows the one standard deviation (1σ) count variation (as a percentage of FS counts) versus counter gate time. To complete an integrating A/D conversion, the output frequency of the VFC110 must be counted.
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PACKAGE OPTION ADDENDUM www.ti.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.