LTC1642 Linear Technology, LTC1642 Datasheet
LTC1642
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LTC1642 Summary of contents
Page 1
... RESET output can be used to generate a system reset with programmable delay when the supply voltage falls below a programmable voltage. The ON pin can be used to cycle the board power. The LTC1642 is available in the 16-pin SSOP package. , LTC and LT are registered trademarks of Linear Technology Corporation. ...
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... SENSE Pin ................................... – 0. GATE Pin ...................................................– 0.3V to 27V All Other Pins ..........................................– 0.3V to 16.5V Operating Temperature Range LTC1642C ............................................... LTC1642I ............................................ – Storage Temperature Range ................. – 150 C Lead Temperature (Soldering, 10 sec).................. 300 C DC ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are unless otherwise specified ...
Page 3
... N-channel shorts RST TMR to ground. When the timer is turned current from V is connected and the RST TMR pin voltage starts to CC ramp rate of 2/C( F) Volts/second. The timer trips when the voltage reaches 1.23V. LTC1642 = MIN TYP MAX UNITS ...
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... LTC1642 CTIO S ON (Pin 4): Control. When ON is low the GATE pin is grounded and FAULT goes high. The GATE pin voltage starts ramping up one RST TMR timing cycle after ON goes high. Pulsing the ON pin low for at least 2 s also resets the chip when it latches off after a sustained overvoltage or current limit ...
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... Power Supply Ramping In the circuit shown in Figure 1 the LTC1642 and the external N-channel pass transistor Q1 work together to limit charging currents. When power is first applied to V the chip holds Q1’s gate at ground. After a programmable ...
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... To restart, hold the ON pin low for at least 2 s and FAULT will go high. Then take ON high again and the GATE will ramp up after a system timing cycle. Or, configure the LTC1642 to restart itself after the circuit breaker trips by connecting FAULT to the ON pin. ...
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... U U APPLICATIO S I FOR ATIO Automatic Restart After a Current Fault The LTC1642 will automatically attempt to restart itself after the circuit breaker opens if the FAULT output is tied to the ON pin. The circuit is shown in Figure 5, and the waveforms during a load short in Figure 6. During a continuous current limit such as a load short, the N-channel pass transistor’ ...
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... Emitter follower Q2 boosts this cur- rent to trigger crowbar SCR Q3. The ramp time t needed to trip the comparator is : t(ms) = 9.1•C5( F). Once the CRWBR timer trips the LTC1642 latches off: after the overvoltage clears GATE and FAULT remain at ground and CRWBR continues sourcing 1.5mA. To restart the part after the overvoltage clears, hold the ON pin low for at least 2 s and then bring it high ...
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... If there is an overvoltage, and the resistor divider feeding OV is connected to the output of the N-channel pass transistor, the LTC1642 will automatically restart even if FAULT is not tied to ON. If the divider is connected to the input side, the LTC1642 will restart itself only if FAULT is tied to ON, and only after the overvoltage clears ...
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... U U APPLICATIO S I FOR ATIO Undervoltage Monitor The LTC1642 will assert RESET if a monitored voltage falls below a programmable minimum. When the monitored voltage has exceeded its minimum for at least one system timing cycle, RESET goes high. The monitoring circuitry comprises an internal 1.23V bandgap reference, an inter- nal precision voltage comparator and an external resistive divider to monitor the output supply voltage ...
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... TYP 0.008 – 0.012 (0.203 – 0.305) LTC1642 0.189 – 0.196* (4.801 – 4.978) 0.009 (0.229 REF 0.150 – 0.157** (3.810 – 3.988) ...
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... D1 MBRS130T3 4 Q5 Si4412DY R1, 0.005 MTB50N06V R2 R8 100 330 47nF V SENSE GATE CC 5 RESET CRWBR LTC1642 12 – COMP Q2 2N2222 11 + COMP 13 REF C5 GND BRK TMR RST TMR 0. 0 0.33 F 0.33 F C16 C17 + + 330 F ...