ltc4221 Linear Technology Corporation, ltc4221 Datasheet

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... IRF7413 10Ω 100nF 10Ω * 100nF V SENSE1 GATE1 V CC1 CC2 21k ON1 10k 13.3k ON2 LTC4221 10k FAULT GND TIMER 470nF LTC4221 U TM controller that at the FILTER pin), then FILTER V OUT1 3.3V/5A 0.004Ω IRF7413 V OUT2 2.5V/5A 14.3k SENSE2 GATE2 FB2 5.11k 10k 10k PWRGD2 PWRGD2 ...

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... TIMER Pin .................................................. – 0. GATE Pins (Note 3) ................................... – 0.3V to 21V PWRGD, FAULT, FILTER Pins ................... – 0.3V to 17V Operating Temperature Range LTC4221C ............................................... 0°C to 70°C LTC4221I ............................................ – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300° ORDER I FOR ATIO ...

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... PWRGD CC1 Normal Cycle – 200mV) Step SENSE – 50mV) Step. SENSE FILTER Open LTC4221 MIN TYP MAX UNITS μA ● –7 –9.5 –12 μA ● 75 100 125 16 mA ● 4.5 13 ● ...

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... LTC4221 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER t FAULT Low to GATE n Discharging P(FAULT-GATE Comparator Trip to GATE n P(OV-GATE) Discharging t Filter Comparator Trip to GATE n P(FILTER-GATE) Discharging t Circuit Breaker Reset Delay Time RESET t Turn Off Propagation Delay P(ON-GATE) Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired ...

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... – 1.5V CC2 CC1 T = 25° ΔV GATE1 13 12 ΔV GATE2 125 (V) CC1 LTC4221 V vs Temperature SENSE(SC) 26 CC1 CC1 V = 3.3V CC2 25.8 25.6 25.4 25.2 25.0 24.8 24.6 24.4 16 – – TEMPERATURE (°C) 4221 G08 I vs Temperature GATE(DN) ...

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... LTC4221 W U TYPICAL PERFOR A CE CHARACTERISTICS ΔV (V – GATE2 GATE2 CC1 vs Temperature 2.7V CC1 CC2 3.3V CC1 CC2 V = 13.5V 13.5V 14 CC1 CC2 100 –50 – TEMPERATURE (°C) 4221 G16 V vs Temperature ON(RESET) 0.440 CC1 V = 3.3V 0.435 CC2 ...

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... TMR(H) 1.240 CC2 1.238 1.236 1.234 1.232 1.230 1.228 1.226 1.224 V CC1 V 1.222 CC1 V CC1 1.220 125 –50 – TEMPERATURE (°C) LTC4221 I vs Temperature FILTER(DN) 2. 2.7V CC2 FILTER 1.95 = 13.5V 1.90 1.85 1.80 1.75 1.70 1.65 100 125 50 –50 – TEMPERATURE (°C) 4221 G26 ...

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... LTC4221 W U TYPICAL PERFOR A CE CHARACTERISTICS I vs Temperature FAULT(UP) –3 2.7V CC2 CC1 CC1 FAULT –3 13.5V CC1 –3.5 –3.7 –3.9 –4.1 –4.3 –4.5 –50 – 100 TEMPERATURE (°C) 4221 G34 V /V PWRGD(OL) FAULT(OL) vs Temperature 0.500 1.6mA ...

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... FAULT (Pin 7): Fault Status Input/Output. FAULT is a bidirectional pin input, pulsing V set the FAULT latch and bring the LTC4221 into the fault state output, FAULT is pulled high by an internal 3.8μA pull-up under normal operating conditions. When an overcurrent fault is detected by a SENSE pin or a overvoltage fault detected pin, the FAULT latch is set and the LTC4221 goes into the fault state ...

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... LTC4221 W BLOCK DIAGRA V CHARGE CC1 PUMP 1 OSCILLATOR CHARGE V PUMP 2 CC1 ON1 1 ON2 16 V CC1 105μA FILTER 8 1.8μA V CC1 3.8μA 0.816V FAULT 7 V CC1 + 9mV TO 25mV – CC1 V CC1 + 100mV – SENSE1 3 0.822V + 0.617V – FB1 5 COMPARATOR V CC2 + 9mV TO 25mV – ...

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... The flow of current may damage the connector pins and glitch the power bus, causing other boards in the system to reset. The LTC4221 is designed to turn on and off a circuit board’s supply voltages in a controlled manner, allowing insertion or removal without glitches or connector dam- age ...

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... TMR(L) ON(OFF) 9.5μA GATE(OV) 25mV 9mV + ΔV FB1 > V FB(UV) FB(HYST) + ΔV FB2 > V FB(UV) INITIAL TIMING CHANNEL 1 START-UP Figure 1. LTC4221 Operation FILTER(TH) + ΔV FAULT(TH) FAULT(HYST) CHANNEL 1 SLOW COMPARATOR ARMED CHANNEL 2 SLOW COMPARATOR ARMED 20μA V FILTER(TH) 1.8μA 105μA ...

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... V . CC2 ON Pin Functions The ON1 pin serves as a global reset for the LTC4221. It has an internal reset comparator with a high-to-low thresh- old of 0.4V, a 25mV hysteresis and a high-to-low glitch filter of 15μs. Pulling ON1 below this threshold will put the LTC4221 into a reset state in which the TIMER is pulled low by an internal N-channel MOSFET pull-down, the GATE pins are pulled low by separate internal 100μ ...

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... LTC4221 U U APPLICATIO S I FOR ATIO (UVL 0.851V ON1 TIMER GATE1 V OUT1 PWRGD1 ON2 GATE2 V OUT2 UVLO sequential power up from time points and a sequential power-down programmed from time points 9 to 11. To achieve this the circuit requires the functionality of the PWRGD1 pin and will be featured in the next section ...

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... FB pin from deasserting its PWRGD. The relationship between glitch filter time and an FB pin transient voltage is shown in Figure 4. Using the functionality of the PWRGD1 pin, the LTC4221 can be configured to do sequential power-up and power-down as shown by the circuit in Figure 5. Referring back to Figure 3, ...

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... Intermittent overloads may exceed the current limit as in Figure 7, but if the duration is sufficiently short, the FILTER pin may not reach the V LTC4221 will not shut down. To handle this situation, the FILTER discharges with 1.8μA whenever both V below 25mV. Any intermittent overload with an aggregate ...

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... Autoretry After a Fault Once the LTC4221 circuit breaker is tripped, FAULT is latched low and both GATE pins are pulled to ground. To 4221 F08 clear the internal FAULT latch and to restart the LTC4221, its ON1 pin must be pulsed below its reset threshold (V ON(RESET) ELECTRONIC CIRCUIT BREAKER ARMED ...

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... As shown in Figure 10, the FAULT (which has an internal 3.8μA pull-up current source) and both ON pins are connected together. The timing diagram in Figure 11 illustrates a simultaneous start-up sequence where the LTC4221 is powered up into a load overcurrent condition on channel 1. After the slow comparators are BACKPLANE PCB EDGE ...

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... 851 . V – • ON μ shown in the timing diagram of Figure 11, the autoretry circuitry will attempt to restart the LTC4221 with a duty cycle STARTUP Duty Cycle = + + INITIAL t is defined in Equation 1 and t FILTER tion the initial timing cycle delay, is given in INITIAL Equation 9 located in the Initial Timing Cycle section ...

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... When the card is being inserted into the bus connector, the long pins mate first which brings up the supplies at time point 1 of Figure 13. The LTC4221 is in reset mode as the ON1 pin is low. Both GATE pins and the TIMER pin are pulled low. At time point 2, the short pin makes contact and both ON pins are pulled high ...

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... MOSFET constant during the start-up cycle. The timing diagram in Figure 14 illustrates the operation of the LTC4221 in a channel start-up cycle with limited inrush ...

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... GATE n pin’s internal zener clamp during transient events. absolute maximum rating of ±20V A MOSFET with meets the two criteria for all the LTC4221 application ranges from 1V to 13.5V. Typically most 10V gate rated MOSFETs absolute maximum ratings of ±20V or greater, so have external V zener clamp is needed ...

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... A recommended layout for the SENSE resistors, the power MOSFETs, V GATE drive components around the LTC4221 is shown in Figure 16. For proper operation of the LTC4221’s elec- tronic circuit breaker, a 4-wire Kelvin connection to each SENSE resistor is used. Also, PCB layout for the external N-channel MOSFETs emphasizes optimal thermal man- agement of MOSFET power dissipation to keep θ ...

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... CHANNEL 1 W INPUT NOTE: DRAWING IS NOT TO SCALE *ADDITIONAL DETAILS OMITTED FOR CLARITY Figure 16. Recommended Layout for LTC4221 R U APPE DIX Table 1 lists some current sense resistors that can be used with the circuit breaker. Table 2 lists some power MOSFETs that are available. Table 3 lists the web sites of several Table 1 ...

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... ISS ON Semiconductor = 1570pF ISS ON Semiconductor = 2600pF ISS SENSE2 0.007Ω IRF7413 SENSE2 GATE2 20k CC2 12 FB2 PG2 5.11k 10k 11 PWRGD2 LTC4221 6 PWRGD1 R 32.4k 5 FB1 R 5.11k 4221 TA02 V OUT1 OUT2 3.3V 2.5A R PG1 10k PWRGD2 PWRGD1 F1 F2 4221fa 25 ...

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... LTC4221 6 PWRGD1 5 FB1 Q1 IRF7413 R Q2 SENSE2 0.004Ω IRF7413 14.3k SENSE2 GATE2 CC2 12 FB2 PG2 5.11k 10k 11 PWRGD2 LTC4221 6 PWRGD1 5 FB1 V OUT1 3. OUT2 2. PG1 10k PWRGD2 PWRGD1 R F1 20k R F2 5.11k 4221 TA03 V OUT1 3. OUT2 2 ...

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... IRF7413 R F3 14. SENSE1 GATE1 V SENSE2 GATE2 CC2 12 FB2 R F4 5.11k 11 PWRGD2 LTC4221 6 PWRGD1 5 FB1 4221 TA05 .189 – .196* .0250 BSC (4.801 – 4.978 .229 – .244 (5.817 – 6.198 OUT1 3 ...

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... Sequenced Power Good Outputs Q1 V IRF7413 3. SENSE2 0.004Ω IRF7413 V 2. 14.3k SENSE2 GATE2 CC2 FB2 R F4 5.11k PWRGD2 LTC4221 PWRGD1 R F1 20k FB1 R F2 5.11k 4221 TA06 LT 0707 REV A • PRINTED IN THE USA © LINEAR TECHNOLOGY CORPORATION 2004 OUT1 OUT2 4221fa ...