LTC1645 Linear Technology, LTC1645 Datasheet
LTC1645
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LTC1645 Summary of contents
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... An additional spare com- parator is available for monitoring a second supply voltage. The LTC1645 is available in the 8- and 14-pin SO packages. , LTC and LT are registered trademarks of Linear Technology Corporation. Hot Swap is a trademark of Linear Technology Corporation. V ...
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... Pin Voltage Threshold Hysteresis COMPHST 2 U (Note 1) Output Current GATE1, GATE2 ............................................... 20mA + 0.3V) Operating Temperature Range CC1 LTC1645C ............................................... 0.3V) LTC1645I ............................................ – CC1 + 0.3V) Storage Temperature Range ................. – 150 C CC2 Lead Temperature (Soldering, 10 sec).................. 300 ORDER PART NUMBER V 1 CC2 ...
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... Supply Current vs Voltage CC2 3 3.0 2.5 2 2.375V CC1 1.5 1 12V CC1 0 (V) CC2 1645 G02 LTC1645 = MIN TYP MAX 1.212 1.230 1.248 1 9 – 2.3 – 2 – 1 1.5 – 12.5 – 10 – 7 4.5 16 0.375 ...
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... LTC1645 W U TYPICAL PERFOR A CE CHARACTERISTICS GATE Voltage vs Supply Voltage HIGHEST V (V) CC 1645 G04 RESET, FAULT, COMPOUT Output Voltage vs Temperature 450 CC1 400 SINK CURRENT = 3mA 350 300 250 200 150 SINK CURRENT = 1 ...
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... V (Pin 1/Pin 1): Positive Supply Input. V CC2 from 1.2V to 12V for normal operation. I 0.2mA. An undervoltage lockout circuit disables the LTC1645 whenever the voltage at V SENSE2 (Pin 2/Pin 2): V Circuit Breaker Set Pin. With CC2 a sense resistor placed in the supply path between V and SENSE2, the circuit breaker trips when the voltage across the resistor exceeds 50mV for more than 1 ...
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... LTC1645 CTIO S (14-Lead Package/8-Lead Package) Whenever the timer is inactive, an internal N-channel FET shorts the TIMER pin to ground. Activating the timer connects current source from V and the voltage starts to ramp up with a slope dv/ When the voltage reaches the trip point (1.23V), TIMER the timer is reset by pulling the TIMER pin back to ground ...
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... These transient currents can cause permanent damage to the connector pins and produce glitches on the system supply, resetting other boards in the system. The LTC1645 is designed to turn a board’s supply voltages on and off in a controlled manner, allowing the board to be safely inserted or removed from a live backplane. The chip ...
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... The opposite is true for LTC1645 Hot Swap circuits on a daughterboard. In most cases, on the powered side of the N-channel FET switches (V capacitor present. An abrupt connection, produced by ...
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... FET capacitance. The absolute maximum V potential for the LTC1645 13.2V; any circuit with an input greater should be scrutinized for ringing. A well-bypassed backplane should ...
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... IRF7413 V OUT + C LOAD 10 0.1 F LTC1645 1645 F06 V CC Figure 6. Transient Suppressor Clamp R1 0.01 10 POWER LEADS 0.1 F LTC1645 1645 F07a (b) V Figure 7. Snubber “Fixes” 12V 0V 1 s/DIV 1645 F06a Waveform Clamped by a Transient Suppressor IRF7413 V OUT + C LOAD 10 0.1 F 1645 F07 12V 0V 1 s/DIV 1645 F07b Waveform Damped by a Snubber ( ...
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... U U APPLICATIO S I FOR ATIO Supply Glitching LTC1645 Hot Swap circuits on the backplane are generally used to provide power-up/down sequence at insertion/ removal as well as overload/short-circuit protection short-circuit occurs at supply ramp-up, the circuit breaker 12V 1 s/DIV (a) V Short-Circuit Supply Current Glitch Without Any Limiting ...
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... Characteristics: Glitch Filter Time vs Feedback Transient. Timer The system timing for the LTC1645 is generated by the circuitry shown in Figure 11. The timer is used to set the turn-on delay after the ON pin goes high. It also sets the delay before the RESET pin goes high after the FB pin exceeds 1 ...
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... A. For a 200ms delay, use a 0.33 F TIMER capacitor. Electronic Circuit Breaker The LTC1645 features an electronic circuit breaker func- tion that protects against short circuits or excessive out- put currents. By placing sense resistors between the supply inputs and sense pins of the supplies, the circuit breaker trips whenever the voltage across either sense resistor is greater than 50mV for more than 1 ...
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... GATE n pins being pulled immediately to ground (instead drops below the of ramping down) by the ON pin going below 0.4V. OUT2 Power Supply Tracking and Sequencing Applications The LTC1645 is able to sequence V ways, including ramping V ramping V first and V OUT1 V and V ...
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... Referring to Figure 18, a diode-or circuit provides power to the LTC1645 if either supply is up. Schottky diodes are used to prevent the voltage at V out threshold. This application assumes that if a supply is not present, the supply input is floating ...
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... Figure 17. Ramping Up 5V Followed by 3.3V Q1A Q1B IRF7313 D1 1/2 BAT54C Q2A 10 IRF7313 D2 1/2 BAT54C 0.1 F 25V GATE1 V V SENSE2 GATE2 SENSE1 CC2 CC1 10 COMP ON COMPOUT LTC1645 (14-LEAD) 4 FAULT RESET TIMER GND 11 7 0.33 F Figure 18. Power Supply Multiplexer + C LOAD2 + C LOAD1 0.01 F 10k 10k 25V 28k 1% 14.7k 1% 10k R HYST 1% 681k ...
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... U U APPLICATIO S I FOR ATIO Using the LTC1645 as a Linear Regulator This application uses the LTC1645 to Hot Swap one primary supply and generate a secondary low dropout regulated supply. Figure 19 shows how to switch a 5V supply and create a 3.3V supply using the spare compara- tor and one additional transistor ...
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... FB pin resistor divider to the other side of the output pass FET (Q2) allows the LTC1649 to compensate for the voltage drop across Q2, assuring an accurate voltage output. The voltage at the LTC1645’s ON pin reaches 0.8V when V IN timing cycle later. As the regulator’s output rises, D2 pulls ...
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... U U APPLICATIO S I FOR ATIO W U LTC1645 19 ...
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... LTC1645 U U APPLICATIO S I FOR ATIO ...
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... The transistors listed in Table 1 or other similar transistors are recommended for use with the LTC1645. Low voltage applications may require the use of logic-level FETs; ensure their maximum V rating is sufficient for the GS application ...
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... LTC1645 PACKAGE DESCRIPTIO 0.010 – 0.020 (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.016 – 0.050 (0.406 – 1.270) * DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" ...
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... TYP 0.014 – 0.019 (0.355 – 0.483) TYP LTC1645 0.337 – 0.344* (8.560 – 8.738 0.150 – 0.157** (3.810 – 3.988 0.004 – 0.010 (0.101 – ...
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... FAX: (408) 434-0507 www.linear-tech.com Dual Supply Hot Swap with Tracking Outputs Q1 0.01 * 1/2 Si4920DY Q2 10 0.01 * 1/2 Si4920DY SENSE1 GATE1 V SENSE2 GATE2 CC1 CC2 8 + COMP 9 COMPOUT LTC1645 (14-LEAD RESET TIMER GND OUT1 3. 2.5A C 1N4002 LOAD1 D3 D2 MBR0530T1 1N4002 V OUT2 2.5V + 2.5A ...