Electronic Components Datasheet Search |
|
ICL8068A Datasheet(PDF) 10 Page - Intersil Corporation |
|
ICL8068A Datasheet(HTML) 10 Page - Intersil Corporation |
10 / 23 page 10 Component Value Selection For optimum performance of the analog section, care must be taken in the selection of values for the integrator capacitor and resistor, auto-zero capacitor, reference voltage, and conversion rate. These values must be chosen to suit the particular application. Integrating Resistor The integrating resistor is determined by the full scale input voltage and the output current of the buffer used to charge the integrator capacitor. This current should be small compared to the output short circuit current such that thermal effects are kept to a minimum and linearity is not affected. Values of 5 µAto 40µA give good results with a nominal of 20 µA. The exact value may be chosen by: NOTE: If gainisusedinthe buffer amplifier, then: Integrating Capacitor The product of integrating resistor and capacitor is selected to give 9V swing for full scale inputs. This is a compromise between possibly saturating the integrator (at +14V) due to tolerance buildup between the resistor, capacitor and clock and the errors a lower voltage swing could induce due to offsets referred to the output of the comparator. In general, the value of CINT is given by: A very important characteristic of the integrating capacitor is that it has low dielectric absorption to prevent roll-over or ratiometric errors. A good test for dielectric absorption is to use the capacitor with the input tied to the reference. This ratiometric condition should be read half scale 1.0000, and any deviation is probably due to dielectric absorption. Polypropylene capacitors give undetectable errors at reasonable cost. Polystyrene and polycarbonate capacitors may be used in less critical applications. Auto-Zero and Reference Capacitor The size of the auto-zero capacitor has some influence on the noise of the system, with a larger value capacitor giving less noise. The reference capacitor should be large enough such that stray capacitance to ground from its nodes is negligible. When gain is used in the buffer amplifier the reference capacitor should be substantially larger than the auto-zero capacitor. As a rule of thumb, the reference capacitor should be approximately the gain times the value of the auto-zero capacitor. The dielectric absorption of the reference cap and auto-zero cap are only important at power-on or when the circuit is recovering from an overload. Thus, smaller or cheaper caps can be used here if accurate readings are not required for the first few seconds of recovery. FIGURE 5. TIMING DIAGRAM FOR OUTPUTS AUTO COUNTS 10,001 INTEGRATOR BUSY SIGNAL COUNTS 10,000 INTEG. REFERENCE COUNTS MAX 20,001 / 2,001 INTEGRATE D5 D4 D3 D2 D1 AUTO ZERO DIGIT SCAN FOR OVER-RANGE SIGNAL INTEGRATE REFERENCE INTEGRATE D1 D2 D3 D4 D5 †FIRST D5 OF AZ AND REF INT ONE COUNT LONGER STROBE 1000 †/100 COUNTS DIGIT SCAN FOR OVER-RANGE EXPANDED SCALE BELOW /1,000 OVER-RANGE WHEN APPLICABLE UNDER-RANGE WHEN APPLICABLE OUTPUT /1,001 ZERO FULL MEASUREMENT CYCLE 40,002/4,002 COUNTS R INT Full Scale Voltage (See Note) 20 µA ------------------------------------------------------------------------------- = R IN T Bu fferGa in () (Full Scale Voltage) 20 µA -------------------------------------------------------------------------------------------- = C INT 10,000(4-1/2 Digit) 1000(3-1/2 Digit) Clock Period × 20 µA () × Integrator Output Voltage Swing ------------------------------------------------------------------------------------------------------------------------- = ICL8052A/ICL71C03, ICL8068A/ICL71C03 |
Similar Part No. - ICL8068A |
|
Similar Description - ICL8068A |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | 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 |