Electronic Components Datasheet Search |
|
VFC110APG4 Datasheet(PDF) 6 Page - Texas Instruments |
|
VFC110APG4 Datasheet(HTML) 6 Page - Texas Instruments |
6 / 12 page VFC110 SBVS021A − OCTOBER 1988 − REVISED APRIL 2007 www.ti.com 6 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. The internal input resistor, one-shot and integrator capacitors set the full-scale output frequency. The input is applied to the summing junction of the integrator amplifier through the 25k Ω internal input resistor. Pin 14 (the noninverting amplifier input) should be referred directly to the negative side of VIN. The common-mode range of the integrating amplifier is limited to approximately −1V to +1V referred to analog ground. This allows the noninverting input to Kelvin-sense the common connection of VIN, easily accommodating any ground-drop errors. The input impedance loading VIN is equal to the input resistor—approximately 25k Ω. OPERATION AT LOWER FREQUENCIES The VFC110 can be operated at lower frequencies simply by limiting the input voltage to less than the nominal 10V full-scale input. To maintain a 10V FS input and highest accuracy, however, external components are required (see Table 1). Small adjustments may be required in the nominal values indicated. Integrator and one-shot capacitors are added in parallel to internal capacitors. Figure 2 illustrates the connections required for 100kHz full-scale output. The one-shot capacitor, COS, should be connected to logic ground. The one-shot connection (pin 6) is not short-circuit protected. Short-circuits to ground may damage the device. The integrator capacitor’s value does not directly affect the output frequency, but determines the magnitude of the voltage swing on the integrator’s output. Using a CINT equal to COS provides an integrator output swing from 0V to approximately 1.5V. COMPONENT SELECTION Selection of the external resistor and capacitor type is important. Temperature drift of an external input resistor and one-shot capacitor will affect temperature stability of the output frequency. NPO ceramic capacitors will normally produce the best results. Silver-mica types will result in slightly higher drift, but may be adequate in many applications. A low temperature coefficient film resistor should be used for RIN. The integrator capacitor serves as a charge bucket, where charge is accumulated from the input, VIN, and that charge is drained during the one-shot period. While the size of the bucket (capacitor value) is not critical, it must not leak. Capacitor leakage or dielectric absorption can affect the linearity and offset of the transfer function. High-quality ceramic capacitors can be used for values less than 0.01 µF. Use caution with higher value ceramic capacitors. High-k ceramic capacitors may have voltage nonlinearities which can degrade overall linearity. Polystyrene, polycarbonate, or mylar film capacitors are superior for high values. 2 14 V IN 112 11 One− Shot V REF −V S Analog Ground 413 NC 3 6 8 Logic Ground f OUT 0MHz to 4MHz 10 +V S 7 NC 5 NC 50pF(1) NC R PU 680 Ω −15V +15V V L +5V 25k Ω(1) 0V to +10V NOTE: (1) Nominal values ( ±20%). Figure 1. 4MHz Full-Scale Operation |
Similar Part No. - VFC110APG4 |
|
Similar Description - VFC110APG4 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |