Moteur de recherche de fiches techniques de composants électroniques |
|
ISL21070CIH325Z-TK Fiches technique(PDF) 8 Page - Renesas Technology Corp |
|
ISL21070CIH325Z-TK Fiches technique(HTML) 8 Page - Renesas Technology Corp |
8 / 12 page ISL21070 FN7599 Rev 4.00 Page 8 of 12 September 3, 2015 Board Mounting Considerations For applications requiring the highest accuracy, board mounting location should be reviewed. Placing the device in areas subject to slight twisting can cause degradation of the accuracy of the reference voltage due to die stresses. It is normally best to place the device near the edge of a board, or the shortest side, as the axis of bending is most limited at that location. Obviously, mounting the device on flexprint or extremely thin PC material will likewise cause loss of reference accuracy. Board Assembly Considerations FGA references provide high accuracy and low temperature drift but some PC board assembly precautions are necessary. Normal Output voltage shifts of 100µV to 1mV can be expected with Pb-free reflow profiles or wave solder on multi-layer FR4 PC boards. Precautions should be taken to avoid excessive heat or extended exposure to high reflow or wave solder temperatures, this may reduce device initial accuracy. Post-assembly x-ray inspection may also lead to permanent changes in device output voltage and should be minimized or avoided. If x-ray inspection is required, it is advisable to monitor the reference output voltage to verify excessive shift has not occurred. If large amounts of shift are observed, it is best to add an X-ray shield consisting of thin zinc (300µm) sheeting to allow clear imaging, yet block x-ray energy that affects the FGA reference. Special Applications Considerations In addition to post-assembly examination, there are also other X-ray sources that may affect the FGA reference long term accuracy. Airport screening machines contain X-rays and will have a cumulative effect on the voltage reference output accuracy. Carry-on luggage screening uses low level X-rays and is not a major source of output voltage shift, however, if a product is expected to pass through that type of screening over 100 times, it may need to consider shielding with copper or aluminum. Checked luggage X-rays are higher intensity and can cause output voltage shift in much fewer passes, thus devices expected to go through those machines should definitely consider shielding. Note that just two layers of 1/2 ounce copper planes will reduce the received dose by over 90%. The leadframe for the device which is on the bottom also provides similar shielding. If a device is expected to pass through luggage X-ray machines numerous times, it is advised to mount a 2-layer (minimum) PC board on the top, and along with a ground plane underneath will effectively shield it from 50 to 100 passes through the machine. Since these machines vary in X-ray dose delivered, it is difficult to produce an accurate maximum pass recommendation. Noise Performance and Reduction The output noise voltage in a 0.1Hz to 10Hz bandwidth is typically 30µVP-P. The noise measurement is made with a bandpass filter made of a 1 pole high-pass filter with a corner frequency at 0.1Hz and a 2-pole low-pass filter with a corner frequency at 12.6Hz to create a filter with a 9.9Hz bandwidth. Wideband noise is reduced by adding capacitor to the output, but the value should be limited to 1nF or less to insure stability. Temperature Drift The limits stated for output accuracy over-temperature are governed by the method of measurement. For the -40°C to 85°C temperature range, measurements are made at +25°C and the two extremes. This measurement method combined with the fact that FGA references have a fairly linear temperature drift characteristic insures that the limits stated will not be exceeded over the temperature range. ISL21070 Used as a Low Cost Precision Current Source Using an N-JET and the ISL21070, a precision, low cost, high impedance current source can be created. The precision of the current source is largely dependent on the tempco and accuracy of the reference. The current setting resistor contributes less than 20% of the error. FIGURE 17. ISL21070 USED AS A LOW COST PRECISION CURRENT SOURCE +8V TO 28V 0.01µF VIN VOUT 1k RSET 0.1% 10ppm/°C ISY ~ 11µA IL AT 0.1% ACCURACY ~2.5011mA ISL21070-2.5 ZOUT > 100M ISET VOUT ISET = RSET IL = ISET + IRSET VOUT = 2.5V GND |
Numéro de pièce similaire - ISL21070CIH325Z-TK |
|
Description similaire - ISL21070CIH325Z-TK |
|
|
Lien URL |
Politique de confidentialité |
ALLDATASHEET.FR |
ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants 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 |