PDF LTC4223-2 Data sheet ( Hoja de datos )

Número de pieza	LTC4223-2
Descripción	Dual Supply Hot Swap Controller
Fabricantes	Linear Technology
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No Preview Available ! www.DataSheet4U.com FEATURES ■ Allows Safe Insertion into Live AMC or MicroTCA Backplane ■ Controls 12V Main and 3.3V Auxiliary Supplies ■ Limits Peak Fault Current in ≤1μs ■ Adjustable Current Limit with Circuit Breaker ■ Integrated 0.3Ω AUX Switch ■ High Side Current Sense ■ Gate Drive for External N-Channel MOSFET ■ Adjustable Response Time for Overcurrent Protection ■ Adjustable Supply Voltage Power-Up Rate ■ Thermal Shutdown Protection ■ LTC4223-1: Latch Off After Fault ■ LTC4223-2: Automatic Retry After Fault ■ 16-Lead SSOP and 5mm × 4mm DFN Packages APPLICATIONS ■ Advanced Mezzanine Card, MicroTCA Systems ■ Workstations and Server I/O ■ Telecom Networks LTC4223-1/LTC4223-2 Dual Supply Hot Swap Controller for Advanced Mezzanine Card DESCRIPTION The LTC®4223 positive voltage Hot SwapTM controller allows a board to be safely inserted and removed from a live AMC or MicroTCA backplane. It controls the main 12V supply with an external N-channel MOSFET and the 3.3V auxiliary supply with an integrated switch. The 12V output ramp rate is adjustable and includes inrush current limiting. The 12V output is also protected against short circuit faults with a fast acting current limit and a 5% accurate timed circuit breaker. The 3.3V output includes both soft start and overcurrent protection. The LTC4223 features a current monitor output for the 12V supply, and reports fault and power-good status for both supplies. It also detects card presence and allows independent control of the 12V and auxiliary 3.3V sup- ply outputs. The LTC4223-1 features a latch-off circuit breaker, while the LTC4223-2 provides automatic retry after a fault. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Advanced Mezzanine Card Application 6mΩ Si7336ADP 12V 10Ω 15nF 47Ω 12V 7.4A 12VIN 12VSENSE 12VGATE 3.3V AUXIN 51Ω VCC 330nF AUXON 12ON AUXPGOOD 12PGOOD FAULT LTC4223-1/LTC4223-2 IPMC ADC 12IMON GND TIMER 0.1μF 12VOUT AUXOUT 3.3V 150mA EN 422312 TA01a CARRIER MODULE CONNECTOR CONNECTOR Normal Power-Up Waveform EN 5V/DIV AUXOUT 5V/DIV 12VOUT 5V/DIV AUXPGOOD 5V/DIV 12PGOOD 5V/DIV 20ms/DIV 422312 TA01b 422312f 1 1 page www.DataSheet4U.com LTC4223-1/LTC4223-2 TYPICAL PERFORMANCE CHARACTERISTICS Speciﬁcations are TA = 25°C, VCC = 3.3V, VAUXIN = 3.3V, V12VIN =12V, unless otherwise speciﬁed. ICC vs VCC 1.6 Supply Current vs Temperature 1.0 12IMON Gain Ratio vs Temperature 35 1.2 0.8 VCC 34 0.6 12VIN 0.8 33 AUXIN 0.4 0.4 0.2 32 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 VCC (V) 422312 G01 12IMON Output Voltage vs Sense Voltage 4 0 – 50 – 25 0 25 50 TEMPERATURE (°C) 75 100 422312 G02 12VOUT Power-Good Threshold vs Temperature 10.4 31 –50 –25 0 25 50 TEMPERATURE (°C) 70 100 422312 G03 AUXOUT Power-Good Threshold vs Temperature 2.92 3 10.3 RISING 2.90 RISING FALLING FALLING 2 10.2 2.88 1 10.1 2.86 0 0 20 40 60 80 100 120 140 SENSE VOLTAGE (mV) 422312 G04 Circuit Breaker Trip Voltage vs Temperature 52 10.0 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 422312 G05 Active Current Limit Sense Voltage vs Temperature 62 51 61 50 60 49 59 48 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 422312 G07 58 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 422312 G08 2.84 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 422312 G06 AUX Active Current Limit vs Temperature 250 240 230 220 210 200 – 50 – 25 0 25 50 TEMPERATURE (°C) 75 100 422312 G09 422312f 5 5 Page www.DataSheet4U.com LTC4223-1/LTC4223-2 APPLICATIONS INFORMATION Several conditions must be met before the external and internal switches are allowed to turn on. First VCC and the input supplies (12VIN, AUXIN) must exceed their undervoltage lockout thresholds. Next TIMER must be <0.2V and ⎯E⎯N must be pulled low. Once these conditions are met, a debounce timing cycle is initiated when AUXON or 12ON pin is toggled from low to high. These two control pins turn on/off the 3.3V auxiliary and 12V supplies. At the end of the debounce cycle, the ON pins and fault status are checked. If both ON pins are high and fault is cleared, the 3.3V auxiliary supply starts up ﬁrst followed by the 12V supply. Note that the turn-on delay for the AUXON and 12ON pins is 15μs and 30μs. Figure 2 shows the two supplies turning on in sequence after ⎯E⎯N goes low. By default, the internal pass transistor turns on ﬁrst if both ON pins are high and start-up conditions met. The output is current limited at 240mA by its internal ACL ampliﬁer as the load current charging the output capaci- tor increases. This causes the TIMER to ramp up with a 10μA pull-up. Normally the AUXOUT voltage exceeds its power-good threshold before TIMER time-out and then ⎯A⎯U⎯X⎯P⎯G⎯O⎯O⎯D pulls low. EN 5V/DIV TIMER 2V/DIV AUXOUT 5V/DIV 12VOUT 5V/DIV AUXPGOOD 5V/DIV 12PGOOD 5V/DIV 20ms/DIV 422312 F02 Figure 2. Normal Power-Up Sequence Once AUXOUT signals power is good and the TIMER pin returns to <0.2V, the external MOSFET is then allowed to turn on by charging up the GATE with a 10μA current source (Figure 2). The voltage at the GATE pin rises with a slope equal to 10μA/CG and the supply inrush current ﬂowing into the load capacitor CL1 (see Figure 14) is limited to: IINRUSH = CL1 CG • 10µA The 12V output follows the GATE voltage when the MOSFET turns on. If the voltage across the current sense resistor RS becomes too high, the inrush current is limited by the internal current limit circuitry. Once the output, 12VOUT exceeds its power-good threshold, ⎯1⎯2⎯P⎯G⎯O⎯O⎯D also pulls low. If only the 12ON pin is high at the end of debounce cycle, the external MOSFET turns on ﬁrst. After that, if AUXON pulls high, the internal switch turns on only after the 12V output signals power is good and TIMER <0.2V. Table 1. 12V and Auxiliary Supply Turn-Off Conditions CONDITION RESULT CLEARED BY AUX 12V AUXON Goes Low Turns Off No Effect AUXON High 12ON Goes Low No Effect Turns Off 12ON High ⎯E⎯N Goes High Turns Off Turns Off ⎯E⎯N Low UVLO on VCC UVLO on AUXIN Turns Off Turns Off Turns Off VCC > UVLO No Effect AUXIN > UVLO UVLO on 12VIN AUX Overcurrent Fault No Effect Turns Off 12V Overcurrent Fault Thermal Shutdown No Effect Turns Off Turns Off Turns Off Turns Off Turns Off 12VIN > UVLO AUXON and 12ON Low, ⎯E⎯N High-to-Low, UVLO on VCC 12ON Low, ⎯E⎯N High-to- Low, UVLO on VCC AUXON and 12ON Low, ⎯E⎯N High-to-Low, UVLO on VCC, Temperature < 120°C 422312f 11 11 Page

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