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ISL88021 Fiches technique(PDF) 5 Page - Intersil Corporation |
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ISL88021 Fiches technique(HTML) 5 Page - Intersil Corporation |
5 / 7 page 5 FN8226.1 September 18, 2006 Manual Reset The manual reset input (MR) allows the user to trigger a reset by using a push-button switch or by signaling that pin low. The MR input is an active low debounced input. By connecting a push-button directly from MR to ground, the designer adds manual system reset capability. Reset is asserted if the MR pin is pulled low to less than 100mV for 1µs or longer while the push-button is closed or a reset is signaled. After MR is released, the reset outputs remain asserted for tPOR. MR input has an internal 20k Ω pull up resistor provided. Figure 3 illustrates a typical application diagram for either IC showing both reset outputs being used along with both a manual and signalled reset configuration. The VDD and V2MON thresholds are preset whereas the V3MON is capable of UV (ISL88021) or OV (ISL88022) monitoring of a voltage greater than or less than 0.6V, respectively. Application Considerations Follow good decoupling practices to prevent transients from causing unwanted reset signaling due to switching noises and short duration droops. When using the CPOR pin, reduce layout stray capacitance on this pin to minimize effect on tPOR timing. If no PCB CPOR pad is patterned, the tPOR can be 160ms. Using the ISL88021_22EVAL1 Platform The ISL88021_22EVAL1 board is designed to provide both immediate functional assessment and flexibility to the user. Both ICs are the ‘HF’ variant having a VDD Vth of 4.64V, a V2MON Vth of 3.09V and V3MON Vth of 0.6V. The top IC position is the ISL88021 and is configured to monitor for undervoltage (UV) compliance of a 5V, 3.3V and a 2.5V and signaling the RESET and RESET outputs. The bottom position is the ISL88022 variant, which is configured to measure a 3.3V overvoltage (OV) in addition to UV on both the 5V and 3.3V supplies. RESET and RESET is asserted for at least tPOR when these voltage go out of range. In both cases V3MON interfaces with the monitored supply via a simple resistor divider for comparison to the internal 0.6V reference. A Manual Reset (MR) input is provided on both ICs and is invoked by pulling this input LOW. V3MON CPOR MR PB GND RST RST TO DISPLAY TO µP RESET VMON > 0.6V V2MON VDD 1.8V - 3.3V 3.3V - 5V ISL88021 ISL88022 SIGNAL FIGURE 3. TYPICAL APPLICATION DIAGRAM FIGURE 4. ISL88021_22EVAL1 SCHEMATIC AND PHOTO ISL88021IU8HFZ ISL88022IU8HFZ FIGURE 5. ISL88022EVAL1 3.3V UV AND OV DETECTION RESET# RESPONDING TO MONITORED VOLTAGE RISING AND FALLING RAMP THROUGH THE PROGRAMMED UV AND OV THRESHOLDS MONITORED VOLTAGE. CPOR PIN IS OPEN, tPOR = 150ms ISL88021, ISL88022 |
Numéro de pièce similaire - ISL88021 |
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Description similaire - ISL88021 |
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