DEMO CIRCUIT 1355 LTC4221 QUICK START GUIDE LTC4221 Dual Hot Swap Controller/Power Se- quencer w/ Dual Speed, Dual Level Fault Pro- tection DESCRIPTION Demonstration circuit DC1355 is a dual hot swap DC1355 is assembled to operate with a +12V rail circuit featuring the LTC4221 Dual Hot Swap with 6A maximum current and a +3.3V rail with Controller / Power Sequencer with Dual Speed, 3.0A maximum current. Dual Level Fault Protection Design files for this circuit board are avail- DC1355 facilitates evaluation of the LTC4221 able. Call the LTC factory. performance characteristics including supply , LTC, LTM, LT, Burst Mode, OPTI-LOOP, Over-The-Top and PolyPhase are registered trademarks of Linear Technology Corporation. Adaptive Power, C- ramp-up transients, steady state operation, and Load, DirectSense, Easy Drive, FilterCAD, Hot Swap, LinearView, Module, Micropower SwitcherCAD, Multimode Dimming, No Latency , No Latency overcurrent fault conditions. On board LEDs in- Delta-Sigma, No R , Operational Filter, PanelProtect, PowerPath, Power- SENSE dicate input supply presence, output state, and SOT, SmartStart, SoftSpan, Stage Shedding, SwitcherCAD, ThinSOT, UltraFast and VLDO are trademarks of Linear Technology Corporation. Other product power good conditions. names may be trademarks of the companies that manufacture the products. The first LTC4221 channel controls a rail from 2.7V to 13.5V and the second one from 1V to 13.5V with condition that V V CC2 CC1. PERFORMANCE SUMMARY Specifications are at TA = 25C SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Supply Voltage Channel 1 2.7 13.5 V CC1 V Supply Voltage Channel 2 V V 1.0 13.5 V CC2 CC2 CC1 V Undervoltage Lockout for Chan- V Rising 2.1 2.5 2.675 V CC1(UVL) CC1 nel 1 V Undervoltage Lockout for Chan- V Rising 0.65 0.8 0.975 V CC2(UVL) CC2 nel 2 V SENSEn Threshold Voltage Channeln Fast Comparator Threshold 85 100 115 mV SENSE(FC) V SENSEn Threshold Voltage Channeln Slow Comparator Threshold 20.5 25 29.5 mV SENSE(SC) V SENSEn Voltage at Active Cur- V =0V 4 9 16 mV SENSE(ACL) FBn rent Limit V =0.65V 20.5 25 29.5 mV FBn I GATEn Output Current V = V =2V, V =0V -7 -9.5 -120 uA GATE(UP) ON1 ON1 GATEn I GATEn Output Current V = V =0.6V, V =3.3V 75 100 125 uA GATE(DN) ON1 ON1 GATEn I GATEn Output Current UNLO with V =3.3V or FAULT latched with 16 mA GATE(FSTDN) GATEn V =3.3V GATEn D V External N-Channel Gate Drive V -V for V =2.7V, V =1V 4.5 13 V GATE GATEn CC1 CC1 CC2 V -V for V =3.3V, V =2.5V 5 16 V GATEn CC1 CC1 CC2 1 LTC4221 PERFORMANCE SUMMARY Specifications are at TA = 25C SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V -V for V =5.0V, V =3.3V 8 16 V GATEn CC1 CC1 CC2 V -V for V =12V, V =12V 7 18 V GATEn CC1 CC1 CC2 V ONn Off Threshold High to Low , GATEn Turns Off by 100uA Pull- 0.796 0.821 0.846 V ON(OFF) Down DV ONn Off Threshold Hysteresis 30 mV ON(OFFHYST) V ON1 Reset Threshold V Falling 0.375 0.4 0.425 V ON(RESET) ON1 D ON1 Reset Threshold Hysteresis 25 mV V ON(RESETHYST) V FBn Undervoltage Threshold FBn Falling 0.605 0.617 0.629 V FB(UV) V FBn Overvoltage Threshold FBn Rising 0.805 0.822 0.838 V FB(OV) I FILTER Pull-Up Current During Current Fault Condition -80 -105 -132 A FILTER (UP) I FILTER Pull-Down Current During Normal Cycle 1.15 1.8 2.45 A FILTER (DN) V FILTER Threshold Latched Off Threshold, FILTER Rising 1.18 1.24 1.30 V FILTER(TH) DV FILTER Threshold Hysteresis 105 mV FILTER(HYST) I TIMER Pull-Up Current 1 Initial Timing Cycle -1.2 1.9 -2.6 A TMR(UP1) I TIMER Pull-Up Current 2 Start-Up cycle -15 -20 -25 A TMR(UP2) I TIMER Pull-Down Current V =1.5V, End of Initial Timing Cycle 9 mA TMR(FSTDN) TMR V TIMER High Threshold TMER Rising 1.172 1.234 1.27 V TMR(H) V TIMER Low Threshold TIMER Falling 0.1 0.4 0.5 V TMR(L) OPERATING PRINCIPLES The LTC4221 controls two rails with external N- a rich set of features to support hot swap applica- channel MOSFETs. tion including: Two independent ONn comparators allow ramping Overvoltage protection rails up and down separately or simultaneously. FAULT latch setting and resetting and fault Each channel has two current limit comparators state indication that provide dual level and dual speed overcurrent Adjustable Inrush Current Control circuit breaker protection after the start-up period. Adjustable duration for Current Limit be- If any current sense voltage exceeds 100mV for fore switch is turned off 1us or 25mV for the timeout delay, then the FAULT latch is set and both GATE pins are pulled low. Power-good signaling The LTC4221 is suited for low voltage applications such as a hot board insertion and removal and has QUICK START PROCEDURE Demonstration circuit 1355 is easy to set up to 1. Place jumpers in the initial position: evaluate the performance of the LTC4221. Refer to JP1 (ON2) Off Figure 1. for proper measurement equipment JP2 (ON1) Off setup and follow the procedure below: 2