Datasheet LTC1696 (Analog Devices) - 10
| Manufacturer | Analog Devices |
| Description | Overvoltage Protection Controller |
| Pages / Page | 14 / 10 — APPLICATIONS INFORMATION Glitch Filter Timer. SCR Crowbar |
| File Format / Size | PDF / 178 Kb |
| Document Language | English |
APPLICATIONS INFORMATION Glitch Filter Timer. SCR Crowbar
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LTC1696
APPLICATIONS INFORMATION Glitch Filter Timer SCR Crowbar
The LTC1696 has a programmable glitch filter to prevent The LTC1696 can deliver continuous output current typi- the output from entering its active high latched condition cally 80mA at high supply voltage to trigger an external if transients occur on the FB1 or FB2 pins. The filter time SCR crowbar in the event of an overvoltage condition as delay is programmed externally by an external capacitor shown in the typical application on the front page of the C1 connected to the TIMER/RESET pin. data sheet. The output current decreases when the supply C1• V voltage reduces. It delivers 25mA at a supply voltage of The time delay is given by: t INT D = 5V. At a low supply voltage of 3.3V, the output current ICHG reduces to 10mA and an external NPN emitter follower where V is needed to boost the current in order to drive the SCR INT is the internal reference voltage of 1.185V and I crowbar as shown in Figure 2. The power dissipation CHG is the internal current source charging the external capacitor C1. The current source I due to the high output current at high supply voltage can CHG charging the external timer capacitor is 10µA for small feedback transients and potentially exceed the thermal limit of the package. This is increases to 12µA for large feedback transients (greater avoided by resetting the device rapidly when the external than 100mV) from one feedback input. The charging SCR crowbar has been triggered, so that the device is not current increases to 18µA for large feedback transients kept in the active high state for too long. from both feedback inputs. VOUT2 V POWER 2.5V CC 3.3V SUPPLY VOUT1 1.8 V R2 R4 54.9k 93.1k 1% 1 TIMER/ 6 1% FB1 RESET C1 Q2 RESET R1 1nF 2N7002 44.2k LTC1696 1% 2 5 GND FB2 R3 Q1 SCR 44.2k 2N3904 2N6507 1% 3 4 VCC OUT R5 R6 470Ω C2 22Ω 5% 0.1µF 5% 1696 F02
Figure 2. External SCR with NPN Emitter Follower with Low Voltage Supplies
1696fb 10 For more information www.linear.com/LTC1696
APPLICATIONS INFORMATION Glitch Filter Timer SCR Crowbar
The LTC1696 has a programmable glitch filter to prevent The LTC1696 can deliver continuous output current typi- the output from entering its active high latched condition cally 80mA at high supply voltage to trigger an external if transients occur on the FB1 or FB2 pins. The filter time SCR crowbar in the event of an overvoltage condition as delay is programmed externally by an external capacitor shown in the typical application on the front page of the C1 connected to the TIMER/RESET pin. data sheet. The output current decreases when the supply C1• V voltage reduces. It delivers 25mA at a supply voltage of The time delay is given by: t INT D = 5V. At a low supply voltage of 3.3V, the output current ICHG reduces to 10mA and an external NPN emitter follower where V is needed to boost the current in order to drive the SCR INT is the internal reference voltage of 1.185V and I crowbar as shown in Figure 2. The power dissipation CHG is the internal current source charging the external capacitor C1. The current source I due to the high output current at high supply voltage can CHG charging the external timer capacitor is 10µA for small feedback transients and potentially exceed the thermal limit of the package. This is increases to 12µA for large feedback transients (greater avoided by resetting the device rapidly when the external than 100mV) from one feedback input. The charging SCR crowbar has been triggered, so that the device is not current increases to 18µA for large feedback transients kept in the active high state for too long. from both feedback inputs. VOUT2 V POWER 2.5V CC 3.3V SUPPLY VOUT1 1.8 V R2 R4 54.9k 93.1k 1% 1 TIMER/ 6 1% FB1 RESET C1 Q2 RESET R1 1nF 2N7002 44.2k LTC1696 1% 2 5 GND FB2 R3 Q1 SCR 44.2k 2N3904 2N6507 1% 3 4 VCC OUT R5 R6 470Ω C2 22Ω 5% 0.1µF 5% 1696 F02
Figure 2. External SCR with NPN Emitter Follower with Low Voltage Supplies
1696fb 10 For more information www.linear.com/LTC1696
