Electronic Components Datasheet Search |
|
NIS5112D2R2G Datasheet(PDF) 7 Page - ON Semiconductor |
|
NIS5112D2R2G Datasheet(HTML) 7 Page - ON Semiconductor |
7 / 9 page NIS5112 http://onsemi.com 7 DEVICE OPERATION Basic Operation This device is a self−protected, resettable, electronic fuse. It contains circuits to monitor the input voltage, output current, die temperature, turn−on di/dt and turn−on dV/dt, as well as an enable/timer function. On application of the input voltage, the device will apply the input voltage to the load based on the restrictions of the controlling circuits. The dV/dt of the output voltage can be programmed by the addition of a capacitor to the dV/dt pin, or if left open, the output current will be limited by the internally controlled di/dt. The device will remain on as long as the temperature does not exceed the 135 °C limit that is programmed into the chip. The current limit circuit does not shut down the part but will reduce the conductivity of the FET to maintain a constant current as long as it remains at the set level. The input overvoltage clamp also does not shut down the part, but will limit the output voltage to 15 V in the event that the input exceeds that level. The device can be turned on and off by the enable/timer function, which can also be used to reset the device after a thermal fault if the thermal latch version is chosen. An internal charge pump provides bias for the gate voltage of the internal N−channel power FET and also for the current limit circuit. The remainder of the control circuitry operates between the input voltage (VCC) and ground. dV/dt This circuit is comprised of an operational amplifier and current source as shown in Figure 7. The enable circuit controls a FET that keeps the slew−rate capacitor discharged any time the device is disabled. When the enable pin is released (low−to−high transition) or when power is applied with the enable pin in a high state, the dV/dt capacitor begins to charge due to the 80 mA in the current source. The amplifier controls the output voltage and tracks the voltage on the dV/dt cap scaled by a factor of 2. The output voltage will continue to ramp higher until it reaches the input voltage, or until the 15 V clamp limits it. The equation for the output slew rate is dV/dt = (I/CdV/dt) x 2. Where: I – is 80 mA (internal current source) CdV/dt – is the desired dV/dt capacitor value. The dV/dt ramp begins with a small step of about 200 mV. This step causes a current surge into the output load capacitance which can be seen in Figure 5. The peak level of this surge will be limited to the overload level of the current limit. Figure 7. dV/dt Circuit − + Enable Source dV/dt R R 80 mA Overvoltage Clamp The overvoltage clamp consists of an amplifier and reference. It monitors the output voltage and if the output voltage exceeds 15 V, the gate drive of the main FET is reduced to limit the output. This is intended to allow operation through transients while protecting the load. If an overvoltage condition exists for many seconds, the device may overheat due to the voltage drop across the FET combined with the load current. In this event, the thermal protection circuit would shut down the device. Enable/Timer The enable/timer pin can function either as a direct enable pin, or as a time delay. In the enable mode, an open collector device is connected to this pin. When the device is in its low impedance mode, this pin is low and the operation of the chip is disabled. If a time delay is required, a capacitor is added to this pin. If a capacitor is added without an open collector device, the turn on will be delayed from the time at which the UVLO voltage is reached. If an open collector device is also used, the delay will start from the time that it goes into its high impedance state. The capacitor is charged by an internal current source of 80 mA (typical). The nominal trip voltage of the comparator is 2.5 V and was designed to be compatible with most logic families. In general, logic gates can be tied directly to this pin, but it is recommended that this be tested. |
Similar Part No. - NIS5112D2R2G |
|
Similar Description - NIS5112D2R2G |
|
|
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 |