 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
HI-8426PCI Datasheet(PDF) 4 Page - Holt Integrated Circuits |
|
||||||||||||||||||||||||||||||
HI-8426PCI Datasheet(HTML) 4 Page - Holt Integrated Circuits |
|
|
4 / 18 page  FUNCTIONAL DESCRIPTION HOLT INTEGRATED CIRCUITS 4 SENSING The 8 Sense Channels can be configured to meet the requirements of a variety of conditions and applications. Table 1 summarizes basic function selection and Table 2 gives more details on possible threshold values. For GND/Open sensing, the SNS_SEL pin is connected to GND Referring to the Block Diagram, Figure 2, this selection will connect a 3.3K pull-up resistor through a diode to VLOGIC and a 23.8K resistor through 3 diodes to VWET. These resistors give extra noise immunity for detecting the open state while providing relay wetting current. Configuring Ω HI-8425 (40 pin version) - THRESHOLD SELECT The HI-8425 offers a choice between internally fixed thresholds or external thresholds provided by the user. GND/OPEN SENSING . , HI_SET/LO_SEL and VWET as described below sets the window comparator thresholds, V and V , the open input voltage when open, and the input current. is equal to 10X the voltage on the HI_SET pin. is equal to 10X the voltage on the LO_SET pin. This mode allows the user complete flexibility to define the thresholds and hysteresis levels. For applications that can take advantage of the very small 32 pin chip scale package of the HI-8426, is not available and an internal pull-up makes it mandatory to supply HI_SET and LO_SET externally. For correct operation, the V when open, must be higher than so SO_n will be low. This condition requires VWET to be set greater than (VTHI/0.9 + 2.25V) he standard “Open” signal as characterized by a resistance of 100K or more with respect to signal common. The user should consider this 100K to ground case when setting the thresholds. Ω Ω Ω THS_SEL THS_SEL THI TLO THI THLO THI TLO SENSE_n THI With set to GND, the window comparator thresholds are fixed based on an internal reference. The high threshold, V , and the low threshold, V levels may be found in Table 2. When the internal references are used the HI_SET and LO_SET pins should be connected to GND. For applications with either large GND offsets or thresholds higher than VLOGIC - 0.75V, is set high and the thresholds are set externally, for example by a simple resistor divider off the VLOGIC supply. In this case V V V . Various ARINC standards such as ARINC 763 define t THS_SEL THS_SEL HI-8426 (32 pin version) THRESHOLD SELECT OPEN INPUT VOLTAGE WETTING CURRENT THRESHOLD SELECT WETTING CURRENT For GND/Open applications with VWET open, the wetting current with the input voltage at GND is simply (VLOGIC - 0.75)/3.3K. When applying a higher voltage at the VWET pin the wetting current is (VLOGIC - 0.75)/3.3K + (VWET - 4.2)/127K. Additional wetting current can be achieved by placing an external resistor and a diode between VWET and the individual sense inputs. The 8 Sense Channels can be configured to sense Supply/Open by connecting the SNSE_SEL pin to VLOGIC. Refering to Figure 2, a 32K resistor is switched in series to provide a pull down in addition to the 400K of the comparator input divider to GND. Similar to the GND/Open case configuring , HI_SET/LO_SEL and VWET as described below sets the window compara- tor thresholds, the open input voltage when open and the wetting current. The threshold selections are handled in the same way as stated above for the GND/OPEN case. For set low, the internal reference nominally sets the window comparator. See table 2 for the For set high, the final thresholds are 10X the voltage set on the HI_SET and LO_SET pins. The VWET pin must be left open in the Supply/Open sensing case. For the Supply/Open case the wetting current into the sense input is the current sunk by the effective 28K to GND. For V = 28V, I is 1ma. See Figure 12. SUPPLY/OPEN SENSING Ω Ω Ω THS_SEL THS_SEL THS_SEL V and V threshold levels. THI THLO SENSE_n WET SENSE_n SNSE_SEL OE SO_n Open or > VTHI L (GND/OPEN) L L < VTLO L (GND/OPEN) L H X L (GND/OPEN) H Z Open or < VTLO H (V+/OPEN) L H > VTHI H (V+/OPEN) L L X H (V+/OPEN) H Z H = VLOGIC, L = GND, Z = Hi-Z, X = Don’t Care, V+ = V See Table 2 for values of VTHI/VTLO SUPPLY Table 1. Function Table HI-8425, HI-8426 |
Similar Part No. - HI-8426PCI |
|
Similar Description - HI-8426PCI |
|
|
|
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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
