19-3032; Rev 0; 10/03 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers Features The MAX5930/MAX5931 +1V to +13.2V triple hot-swap controllers provide complete protection for multisupply systems. They allow the safe insertion and removal of circuit cards into live backplanes. These devices hot swap multiple supplies ranging from +1V to +13.2V, provided one supply is at or above +2.7V and only one supply is above 11V. The input voltage rails (channels) can be configured to sequentially turn-on/off, track each other, or have completely independent operation. The discharged filter capacitors of the circuit card provide low impedance to the live backplane. High inrush currents from the backplane to the circuit card can burn up connectors and components, or momentarily collapse the backplane power supply leading to a system reset. The MAX5930/MAX5931 hot-swap controllers prevent such problems by gradually ramping up the output voltage and regulating the current to a preset limit when the board is plugged in, allowing the system to stabilize safely. After the startup cycle is complete, on-chip comparators provide VariableSpeed/BiLevel™ protection against short-circuit and overcurrent faults, and provide immunity against system noise and load transients. The load is disconnected in the event of a fault condition. The MAX5930/MAX5931 fault-management mode is selectable, allowing latched fault or autoretry after a fault condition. The MAX5930/MAX5931 offer a variety of options to reduce external component count and design time. All devices integrate an on-board charge pump to drive the gates of low-cost, external N-channel MOSFETs, an adjustable startup timer, and an adjustable current limit. The devices offer integrated features like startup current regulation and current glitch protection to eliminate external timing resistors and capacitors. The MAX5931L provides an open-drain, active-low status output for each channel, the MAX5931H provides an open-drain, active-high status output for each channel, and the MAX5930 status output polarity is selectable. The MAX5930 is available in a 24-pin QSOP package, and the MAX5931 is available in a 20-pin QSOP package. All devices are specified over the extended -40°C to +85°C temperature range. ♦ Safe Hot Swap for +1V to +13.2V Power Supplies with Any Input Voltage (VIN_) ≥ 2.7V and Only One VIN_ > 11.0V Applications Network Switches, Routers, Hubs Hot Plug-In Daughter Cards RAID Solid-State Circuit Breakers Power-Supply Sequencing/Tracking Base-Station Line Cards Portable Computer Device Bays (Docking Stations) ♦ Adjustable Circuit Breaker/Current-Limit Threshold from 25mV to 100mV ♦ Configurable Tracking, Sequencing, or Independent Operation Modes ♦ VariableSpeed/BiLevel Circuit-Breaker Response ♦ Internal Charge Pumps Generate N-Channel MOSFET Gate Drives ♦ Inrush Current Regulated at Startup ♦ Autoretry or Latched Fault Management ♦ Programmable Undervoltage Lockout ♦ Status Outputs Indicate Fault/Safe Condition Ordering Information PART TEMP RANGE PIN-PACKAGE MAX5930EEG -40°C to +85°C 24 QSOP MAX5931LEEP* -40°C to +85°C 20 QSOP MAX5931HEEP* -40°C to +85°C 20 QSOP *Future product—contact factory for availability. Selector Guide and Typical Operating Circuit appear at end of data sheet. Pin Configurations TOP VIEW POL 1 24 MODE ON2 2 23 ON3 ON1 3 22 LIM2 LIM1 4 IN1 5 21 IN2 MAX5930 20 SENSE2 SENSE1 6 19 GATE2 GATE1 7 18 LIM3 STAT1 8 17 IN3 STAT2 9 16 SENSE3 TIM 10 15 GATE3 LATCH 11 14 GND STAT3 12 13 BIAS QSOP Pin Configurations continued at end of data sheet. VariableSpeed/BiLevel is a trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX5930/MAX5931 General Description MAX5930/MAX5931 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND, unless otherwise noted.) IN_ ..........................................................................-0.3V to +14V GATE_.............................................................-0.3V to (IN_ + 6V) BIAS (Note 1) .............................................. (VIN - 0.3V) to +14V ON_, STAT_, LIM_ (MAX5930), TIM, MODE, LATCH, POL (MAX5930) ..........................-0.3V to (VIN + 0.3V) SENSE_........................................................-0.3V to (IN_ + 0.3V) Current into Any Pin..........................................................±50mA Continuous Power Dissipation (TA = +70°C) 20-Pin QSOP (derate 9.1mW/°C above +70°C)............727mW 24-Pin QSOP (derate 9.5mW/°C above +70°C)............762mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature .....................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C Note 1: VIN is the largest of VIN1, VIN2, and VIN3. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN_ = +1V to +13.2V provided at least one supply is larger than or equal to +2.7V and only one supply is > 11.0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN1 = 12.0V, VIN2 = 5.0V, VIN3 = 3.3V, VON_ = +3.3V, and TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 13.2 V 2.5 5 mA 25 27.5 POWER SUPPLIES IN_ Input Voltage Range Supply Current VIN_ IQ At least one VIN_ ≥ +2.7V and only one VIN_ > 11.0V 1.0 IIN1 + IIN2 + IIN3, VON_ = 2.7V, VIN_ = +13.2V, after STAT_ high CURRENT CONTROL Slow-Comparator Threshold (VIN_ - VSENSE_) (Note 3) VSC,TH LIM_ = GND (MAX5930), MAX5931 (Note 4) TA = +25°C 22.5 TA = -40°C to +85°C 21.0 27.5 80 125 RLIM_ = 10kΩ (MAX5930) RLIM_ x 7.5 x 10-6 + 25mV RLIM_ from LIM_ to GND (MAX5930) Slow-Comparator Response Time (Note 4) Fast-Comparator Threshold (VIN_ - VSENSE_) Fast-Comparator Response Time SENSE_ Input Bias Current tSCD 1mV overdrive 3 ms 50mV overdrive 130 µs 2x VFC,TH tFCD IB SENSE_ mV mV VSC,TH 10mV overdrive, from overload condition 200 VSENSE_ = VIN_ 0.03 ns 1 µA MOSFET DRIVER Startup Period (Note 5) tSTART RTIM = 100kΩ 8.0 10.8 13.6 RTIM = 4kΩ (minimum value) 0.30 0.4 0.55 5 9 14 TIM floating (default) 2 _______________________________________________________________________________________ ms Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers (VIN_ = +1V to +13.2V provided at least one supply is larger than or equal to +2.7V and only one supply is > 11.0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN1 = 12.0V, VIN2 = 5.0V, VIN3 = 3.3V, VON_ = +3.3V, and TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS Charging, VGATE_ = GND, VIN_ = +5V (Note 6) MIN TYP MAX 80 100 125 Discharging, during startup Average Gate Current IGATE Discharging, normal turn-off or triggered by the slow comparator after startup; VGATE_ = 5V, VIN_ = 10V, VON_ = 0V UNITS µA 100 2 3 7 mA Gate-Drive Voltage VDRIVE Discharging, triggered by a fault after startup; VGATE_ = 5V, VIN_ = 10V, (VIN_ VSENSE_) > VFC,TH_ (Note 7) 30 50 120 VGATE_ - VIN_, IGATE_ = 1µA 4.9 5.3 5.6 V Low to high 0.85 0.875 0.90 V ON COMPARATOR ON_ Threshold VON_,TH ON_ Propagation Delay ON_ Voltage Range ON_ Input Bias Current ON_ Pulse-Width Low Hysteresis 25 10mV overdrive 10 VON_ Without false output inversion IBON VON_ = VIN tUNLATCH To unlatch after a latched fault 0.03 mV µs VIN V 1 µA 100 µs DIGITAL OUTPUTS (STAT_) VSTAT_ ≤ 13.2V Output Leakage Current Output Voltage Low VOL_ POL = floating (MAX5930), ISINK = 1mA UVLO Threshold VUVLO Startup is initiated when this threshold is reached by any VIN_ and VON_ > 0.9V (Note 8) UVLO Hysteresis VUVLO,HYST 1 µA 0.4 V 2.65 V UNDERVOLTAGE LOCKOUT (UVLO) UVLO Glitch Filter Reset Time UVLO to Startup Delay tD,GF tD,UVLO Input Power-Ready Threshold VPWRRDY Input Power-Ready Hysteresis VPWRHYST 2.25 2.45 250 VIN < VUVLO maximum pulse width to reset mV 10 µs Time input voltage must exceed VUVLO before startup is initiated 20 37.5 60 ms Any channel, while VIN > VUVLO (Note 9) 0.9 0.95 1.0 V 50 mV LOGIC AND TIMING POL Input Pullup IPOL LATCH Input Pullup MODE Input Voltage POL = GND (MAX5930) 2 4 6 µA ILATCH LATCH = GND 2 4 6 µA VMODE MODE floating (default to sequencing mode) 1.0 1.25 1.5 V 0.4 V Independent-Mode Selection Threshold VINDEP,TH VMODE rising Tracking-Mode Selection Threshold VTRACK,TH VMODE rising 2.7 V _______________________________________________________________________________________ 3 MAX5930/MAX5931 ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VIN_ = +1V to +13.2V provided at least one supply is larger than or equal to +2.7V and only one supply is > 11.0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN1 = 12.0V, VIN2 = 5.0V, VIN3 = 3.3V, VON_ = +3.3V, and TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL MODE Input Impedance CONDITIONS MIN TYP RMODE Autoretry Delay MAX UNITS 200 tRETRY kΩ 64 x Delay time to restart after fault shutdown ms tSTART Note 2: All devices are 100% tested at TA = +25°C. Limits over temperature are guaranteed by design. Note 3: The slow-comparator threshold is adjustable. VSC,TH = RLIM x 7.5µA + 25mV (see the Typical Operating Characteristics). Note 4: The current-limit slow-comparator response time is weighed against the amount of overcurrent, the higher the overcurrent condition, the faster the response time (see the Typical Operating Characteristics). Note 5: The startup period (tSTART) is the time during which the slow comparator is ignored and the device acts as a current-limiter by regulating the sense current with the fast comparator (see the Startup Period section). Note 6: The current available at GATE is a function of VGATE (see the Typical Operating Characteristics). Note 7: After a fault triggered by the fast comparator, the gate is discharged by the strong discharge current. Note 8: Each channel input while the other inputs are at +1V. Note 9: Each channel input while any other input is at +2.7V. Typical Operating Characteristics (Typical Operating Circuits, Q1 = Q2 = Q3 = Fairchild FDB7090L, VIN1 = +12.0V, VIN2 = +5.0V, VIN3 = +1V, TA = +25°C, unless otherwise noted. Channels 1 through 3 are identical in performance. Where characteristics are interchangeable, channels 1 through 3 are referred to as X, Y, and Z.) TOTAL SUPPLY CURRENT vs. INPUT VOLTAGE VINY = VINZ = 2.7V IINX + IINY + IINZ 3 IIN = IIN1 + IIN2 + IIN3 VIN = VINX = VINY = VINZ VON = VON1 = VON2 = VON3 3.0 2.5 VON_ = VINY = VINZ = 2.7V VINX = 2.8V IINY + IINZ 4.0 MAX5930 toc03 5.0 MAX5930 toc01 4 SUPPLY CURRENT vs. TEMPERATURE MAX5930 toc02 SUPPLY CURRENT vs. INPUT VOLTAGE IINX 2 IIN (mA) IIN (mA) 2.0 IIN (mA) MAX5930/MAX5931 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers VON = 0V 3.0 1.0 VON = 3.3V 1 IINX 1.5 2.0 0.5 IINY + IINZ IINY + IINZ 0 1.0 0 4 2 4 6 8 VINX (V) 10 12 14 0 2 4 6 8 VIN (V) 10 12 14 -40 -15 10 35 TEMPERATURE (°C) _______________________________________________________________________________________ 60 85 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers GATE CHARGE CURRENT vs. GATE VOLTAGE VINX = 5V 90 60 VINX = 1V 30 4 6 8 10 12 80 10 15 VGATEX (V) STRONG GATE DISCHARGE CURRENT vs. GATE VOLTAGE STRONG GATE DISCHARGE CURRENT vs. TEMPERATURE 4 VINX = 5V 3 VINX = 3.3V 2 1 VINX = 13.2V 3 VINX = 3.3V 2 1 -15 10 35 60 85 TURN-OFF TIME vs. SENSE VOLTAGE VINX = 5V 4 -40 TEMPERATURE (°C) VONX = 0V VINY = VINZ = 2.7V 5 20 10 RLIMX = 100Ω 1 TURN-OFF TIME (ms) VINX = 13.2V 6 GATE DISCHARGE CURRENT (mA) 5 0 5 VINX (V) VONX = 0V VINY = VINZ = 2.7V VINX = 1V 40 VONX = VINY = VINZ = 2.7V VGATEX = 0V 0 14 MAX5930 toc07 6 2 MAX5930 toc06 VINX = 5V MAX5930 toc08 0 0.1 0.01 SLOW-COMPARATOR THRESHOLD 0.001 FAST-COMPARATOR THRESHOLD VINX = 1V VINX = 1V 0 0.0001 0 4 0 8 12 16 20 -40 -15 10 35 60 0 85 25 50 75 VGATEX (V) TEMPERATURE (°C) VINX - VSENSEX (mV) TURN-OFF TIME vs. SENSE VOLTAGE (EXPANDED SCALE) SLOW-COMPARATOR THRESHOLD vs. RLIMX STARTUP PERIOD vs. RTIM RLIMX = 100Ω 120 100 400 500 40 tSTART (ms) VSC,TH (mV) 125 60 80 1 100 MAX5930 toc12 10 MAX5930 toc10 GATE DISCHARGE CURRENT (mA) 120 0 0 TURN-OFF TIME (ms) VINX = 13.2V 160 MAX5930 toc09 2 VINX = 13.2V 120 200 GATE CHARGE CURRENT (µA) 4 VONW = VINY = VINZ = 2.7V MAX5930 toc11 VDRIVEX (V) 6 150 GATE CHARGE CURRENT vs. TEMPERATURE MAX5930 toc05 VINY = VINZ = 2.7V GATE CHARGE CURRENT (µA) 8 MAX5930 toc04 GATE-DRIVE VOLTAGE vs. INPUT VOLTAGE 60 40 20 20 SLOW-COMPARATOR THRESHOLD 0 0.1 20 25 30 35 40 VINX - VSENSEX (mV) 45 50 0 0 2 4 6 RLIMX (kΩ) 8 10 0 100 200 300 RTIM (kΩ) _______________________________________________________________________________________ 5 MAX5930/MAX5931 Typical Operating Characteristics (continued) (Typical Operating Circuits, Q1 = Q2 = Q3 = Fairchild FDB7090L, VIN1 = +12.0V, VIN2 = +5.0V, VIN3 = +1V, TA = +25°C, unless otherwise noted. Channels 1 through 3 are identical in performance. Where characteristics are interchangeable, channels 1 through 3 are referred to as X, Y, and Z.) Typical Operating Characteristics (continued) (Typical Operating Circuits, Q1 = Q2 = Q3 = Fairchild FDB7090L, VIN1 = +12.0V, VIN2 = +5.0V, VIN3 = +1V, TA = +25°C, unless otherwise noted. Channels 1 through 3 are identical in performance. Where characteristics are interchangeable, channels 1 through 3 are referred to as X, Y, and Z.) TURN-OFF TIME SLOW-COMPARATOR FAULT VSTATX 2V/div 0V VSTATX 2V/div 0V VINX - VSENSEX 25mV/div AC-COUPLED VINX - VSENSEX 100mV/div 0V VGATEX 5V/div 0V VGATEX 5V/div 0V STARTUP WAVEFORMS FAST TURN-ON (CGATE = 0nF, CBOARD = 1000µF) STARTUP WAVEFORMS SLOW TURN-ON (CGATE = 0.22µF, CBOARD = 1000µF) VSTATX 5V/div IOUTX 2A/div MAX5930 toc16 100ns/div MAX5930 toc15 1ms/div VONX 5V/div VON 5V/div VSTATX 5V/div IOUTX 2A/div VGATEX 10V/div VOUTX 5V/div VGATEX 10V/div VOUTX 5V/div 2ms/div AUTORETRY DELAY TURN-ON IN VOLTAGE-TRACKING MODE VINX 2V/div MAX5930 toc18 2ms/div VGATEX 2V/div 0V VPWRRDY 0V VONX 2V/div VOUTX 2V/div 0V VGATEY IOUTX 500mA/div 5V/div 0V 0V 100ms/div 6 MAX5930 toc14 MAX5930 toc13 TURN-OFF TIME FAST-COMPARATOR FAULT MAX5930 toc17 MAX5930/MAX5931 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers VGATEX 4ms/div _______________________________________________________________________________________ Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers MAX5930 toc19 VPWRRDY VINX 2V/div 0V VONX 2V/div VPWRRDY 0V VONX 2V/div 0V VGATEY 5V/div 0V VINX 2V/div MAX5930 toc20 TURN-ON IN XXXX POWER-SEQUENCING MODE TURN-OFF IN XXXX VOLTAGE-TRACKING MODE VGATEY 5V/div VGATEX VGATEX 0V 4ms/div 4ms/div TURN-OFF IN XXXX POWER-SEQUENCING MODE MAX5930 toc22 VPWRRDY MAX5930 toc21 VINX 2V/div 0V TURN-ON IN XXXX MODE INDEPENDENT VINX 2V/div 0V VONX 2V/div VONX 2V/div 0V VGATEY VGATEY VGATEX 5V/div 0V VGATEX 4ms/div TURN-OFF IN XXXX MODE INDEPENDENT STRONG GATE DISCHARGE CURRENT vs. OVERDRIVE VPWRRDY VGATEY 5V/div VGATEX 50 GATE DISCHARGE CURRENT (mA) VINX 2V/div 0V VONX 2V/div 40 MAX5930 toc24 4ms/div MAX5930 toc23 5V/div 0V VONX = VIN VGATE = 5V AFTER STARTUP LIM_ = GND VINX = 12V VINX = 5V 30 20 VINX = 2.7V 10 0V 0 4ms/div 20 25 30 35 40 45 50 VIN_ - VSENSE_ (mV) _______________________________________________________________________________________ 7 MAX5930/MAX5931 Typical Operating Characteristics (continued) (Typical Operating Circuits, Q1 = Q2 = Q3 = Fairchild FDB7090L, VIN1 = +12.0V, VIN2 = +5.0V, VIN3 = +1V, TA = +25°C, unless otherwise noted. Channels 1 through 3 are identical in performance. Where characteristics are interchangeable, channels 1 through 3 are referred to as X, Y, and Z.) Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers MAX5930/MAX5931 Pin Description PIN 8 NAME FUNCTION MAX5930 MAX5931 1 — POL STAT Output-Polarity Select (See Table 3 and the Status Output Section) 2 1 ON2 On/Off Channel 2 Control Input (See the Mode Section) 3 2 ON1 On/Off Channel 1 Control Input (See the Mode Section) 4 — LIM1 Channel 1 Current-Limit Setting. Connect a resistor from LIM1 to GND to set current-trip level. Connect to GND for the default 25mV threshold. Do not leave LIM1 open. 5 3 IN1 6 4 SENSE1 7 5 GATE1 Channel 1 Gate-Drive Output. Connect to gate of external N-channel MOSFET. Channel 1 Supply Input. Connect to a 1V to 13.2V supply voltage and to one end of RSENSE1. Bypass with a 0.1µF capacitor to ground. Channel 1 Current-Sense Input. Connect SENSE1 to the drain of an external MOSFET and to one end of RSENSE1. 8 6 STAT1 Open-Drain Status Signal for Channel 1. STAT1 asserts when hot swap is successful and tSTART has elapsed. STAT1 deasserts if ON1 is low, or if channel 1 is turned off for any fault condition. 9 7 STAT2 Open-Drain Status Signal for Channel 2. STAT2 asserts when hot swap is successful and tSTART has elapsed. STAT2 deasserts if ON2 is low, or if channel 2 is turned off for any fault condition. 10 8 TIM 11 9 LATCH Latch/Autoretry Selection Input. Connect LATCH to GND for autoretry mode after a fault. Leave LATCH open for latch mode. 12 10 STAT3 Open-Drain Status Signal for Channel 3. STAT3 asserts when hot swap is successful and tSTART has elapsed. STAT3 deasserts if ON3 is low, or if channel 3 is turned off for any fault condition. 13 11 BIAS Supply Reference Output. The highest supply is available at BIAS for filtering. Connect a 1nF to 10nF ceramic capacitor from BIAS to GND. No other connections are allowed to BIAS. Startup Timer Setting. Connect a resistor from TIM to GND to set the startup period. Leave TIM unconnected for the default startup period of 9ms. RTIM must be between 4kΩ and 500kΩ. 14 12 GND 15 13 GATE3 Channel 3 Gate-Drive Output. Connect to gate of external N-channel MOSFET. Ground 16 14 SENSE3 Channel 3 Current-Sense Input. Connect SENSE3 to the drain of an external MOSFET and to one end of RSENSE3. 17 15 IN3 Channel 3 Supply Input. Connect to a supply voltage from 1V to 13.2V and to one end of RSENSE3. Bypass with a 0.1µF capacitor to ground. 18 — LIM3 Channel 3 Current-Limit Setting. Connect a resistor from LIM3 to GND to set current-trip level. Connect to GND for the default 25mV threshold. Do not leave LIM3 open. 19 16 GATE2 Channel 2 Gate-Drive Output. Connect to gate of external N-channel MOSFET. 20 17 SENSE2 Channel 2 Current-Sense Input. Connect SENSE2 to the drain of an external MOSFET and to one end of RSENSE2. 21 18 IN2 Channel 2 Supply Input. Connect to a 1V to 13.2V supply voltage and to one end of RSENSE2. Bypass with a 0.1µF capacitor to ground. _______________________________________________________________________________________ Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers PIN NAME MAX5930 MAX5931 22 — LIM2 23 19 ON3 24 20 MODE FUNCTION Channel 2 Current-Limit Setting. Connect a resistor from LIM2 to GND to set current-trip level. Connect to GND for the default 25mV threshold. Do not leave LIM2 open. On/Off Channel 3 Control Input (See the Mode Section) Mode Configuration Input. Mode is configured according to Table 1 as soon as one of the IN_ voltages exceeds UVLO and before turning on OUT_ (see the Mode section). Detailed Description The MAX5930/MAX5931 are circuit-breaker ICs for hotswap applications where a line card is inserted into a live backplane. The MAX5930/MAX5931 operate down to 1V provided one of the inputs is above 2.7V and only one supply is above 11V. Normally, when a line card is plugged into a live backplane, the card’s discharged filter capacitors provide low impedance that can momentarily cause the main power supply to collapse. The MAX5930/MAX5931 reside either on the backplane or on the removable card to provide inrush current limiting and short-circuit protection. This is achieved by using external N-channel MOSFETs, external current-sense resistors, and on-chip comparators. The startup period and current-limit threshold of the MAX5930/MAX5931 can be adjusted with external resistors. Figure 1 shows the MAX5930/MAX5931 functional diagram. The MAX5930 offers three programmable current limits, selectable fault-management mode, and selectable STAT_ output polarity. The MAX5930 features fixed current limits, selectable fault-management mode, and fixed STAT_ output polarity. Mode The MAX5930/MAX5931 supports three modes of operation: voltage-tracking, power-sequencing, and independent mode. Select the appropriate mode according to Table 1. Voltage-Tracking Mode Connect MODE high to enter voltage-tracking mode. While in voltage-tracking mode, all channels turn on and off together. To turn all channels on: • At least one VIN_ must exceed VUVLO (2.45V) for the UVLO to startup delay (37.5ms). • All VIN_ must exceed VPWRRDY (0.95V). • All VON_ must exceed VON,TH (0.875V). • No faults may be present on any channel. The MAX5930/MAX5931 turns off all channels if any of the above conditions are not met. After a fault-latched shutdown, cycle any of the ON_ pins to unlatch and restart all channels. Power-Sequencing Mode Leave MODE floating to enter power-sequencing mode. While in power-sequencing mode, the MAX5930/MAX5931 turn on and off each channel depending on the state of the corresponding VON_. To turn on a given channel: • At least one VIN_ must exceed VUVLO (2.45V) for the UVLO to startup delay (37.5ms). • All VIN_ must exceed VPWRRDY (0.95V). • The corresponding V ON_ must exceed V ON,TH (0.875V). • No faults may be present on any channel. The MAX5930/MAX5931 turn off all channels if any of the above conditions are not met. After a fault-latched shutdown, cycle any of the ON_ pins to unlatch and restart all channels, dependent on the corresponding VON_ state. Independent Mode Tie MODE to GND to enter independent mode. While in independent mode the MAX5930/MAX5931 provide complete independent control for each channel. To turn on a given channel: • At least one VIN_ must exceed VUVLO (2.45V) for the UVLO to startup delay (37.5ms). • The corresponding V IN_ must exceed V PWRRDY (0.95V). • The corresponding V ON_ must exceed V ON,TH (0.875V). Table 1. Operational Mode Selection MODE High (Connect to BIAS) OPERATION Voltage Tracking OPEN Voltage Sequencing GND Independent _______________________________________________________________________________________ 9 MAX5930/MAX5931 Pin Description (continued) MAX5930/MAX5931 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers RLIM1 RTIM LIM1* RLIM2 1nF LTIM BIAS LIM2* POL* IN1 IN2 VSC, TH VFC, TH VFC, TH STARTUP OSCILLATOR VSC, TH RSENSE1 RSENSE2 FAST COMP SENSE1 UVLO BIAS AND REFERENCES 2.45V UVLO SENSE2 TIMING OSCILLATOR SLOW COMP FAST COMP SLOW COMP GATE1 GATE2 CURRENT CONTROL AND STARTUP LOGIC CHARGE PUMP Q1 OUT1 3mA 50mA CURRENT CONTROL AND STARTUP LOGIC DEVICE CONTROL LOGIC SLOW DISCHARGE FAST DISCHARGE CHARGE PUMP Q2 OUT2 SLOW DISCHARGE FAST DISCHARGE 3mA 50mA 100µA 100µA STAT1 STAT2 LIM3* RLIM3 IN3 VSC, TH VFC, TH MAX5930 MAX5931 RSENSE3 FAST COMP UVLO SENSE3 SLOW COMP GATE3 CHARGE PUMP Q3 OUT3 CURRENT CONTROL AND STARTUP LOGIC SLOW DISCHARGE FAST DISCHARGE 3mA 50mA *MAX5930 ONLY. 100µA STAT3 FAULT MANAGEMENT ON INPUT COMPARATORS OPERATION MODE LATCH* ON1 ON2 ON3 MODE Figure 1. Functional Diagram The MAX5930/MAX5931 turn off the corresponding channel if any of the above conditions are not met. During a fault condition on a given channel only, the affected channel is disabled. After a fault-latched shutdown, recycle the corresponding ON_ inputs to unlatch and restart only the corresponding channel. 10 Startup Period RTIM sets the duration of the startup period from 0.4ms (RTIM = 4kΩ) to 51ms (RTIM = 500kΩ) (see the Setting the Startup Period, RTIM section). The default startup period is fixed at 9ms when TIM is floating. The startup period begins after the turn-on conditions are met as described in the Mode section, and the device is not latched or in its autoretry delay (see the Latched and Autoretry Overcurrent Fault Management section). ______________________________________________________________________________________ Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers MAX5930/MAX5931 ON1 ON2 ON3 VUVLO (2.45V) ANY IN_ VPWRRDY (0.95V) IN2 VPWRRDY (0.95V) IN3 VPWRRDY (0.95V) OUT1* OUT2* OUT3* *THE OUT_ DISCHARGE RATE IS A RESULT OF NATURAL DECAY OF THE LOAD RESISTANCE AND CAPACITANCE. Figure 2. Voltage-Tracking Timing Diagram (Provided tD, UVLO Requirement is Met) ______________________________________________________________________________________ 11 MAX5930/MAX5931 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers ON1 ON2 ON3 VUVLO (2.45V) ANY IN_ VPWRRDY (0.95V) IN2 VPWRRDY (0.95V) IN3 VPWRRDY (0.95V) * OUT1 * OUT2 * * OUT3 *THE OUT_ DISCHARGE RATE IS A RESULT OF NATURAL DECAY OF THE LOAD RESISTANCE AND CAPACITANCE. Figure 3. Power-Sequencing Timing Diagram (Provided tD, UVLO Requirement is Met) 12 ______________________________________________________________________________________ Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers Figure 6 shows the startup waveforms. STAT_ is asserted immediately after the startup period if no fault condition is present. ON1 = ON2 = ON3 OVERCURRENT FAULT CONDITION VariableSpeed/BiLevel Fault Protection * OUT1 * OUT2 * OUT3 *THE OUT_ DISCHARGE RATE IS A RESULT OF NATURAL DECAY OF THE LOAD RESISTANCE AND CAPACITANCE. Figure 4. Power-Sequencing Fault Turn-Off The MAX5930/MAX5931 limit the load current if an overcurrent fault occurs during startup instead of completely turning off the external MOSFETs. The slow comparator is disabled during the startup period and the load current can be limited in two ways: 1) Slowly enhancing the MOSFETs by limiting the MOSFET gate-charging current. 2) Limiting the voltage across the external currentsense resistor. During the startup period, the gate-drive current is limited to 100µA and decreases with the increase of the gate voltage (see the Typical Operating Characteristics). This allows the controller to slowly enhance the MOSFETs. If the fast comparator detects an overcurrent, the MAX5930/MAX5931 regulate the gate voltage to ensure that the voltage across the sense resistor does not VariableSpeed/BiLevel fault protection incorporates comparators with different thresholds and response times to monitor the load current (Figure 7). During the startup period, protection is provided by limiting the load current. Protection is provided in normal operation (after the startup period has expired) by discharging the MOSFET gates with a strong 3mA/50mA pulldown current in response to a fault condition. After a fault, STAT_ is deasserted. Use the LATCH input to control whether the STAT_ outputs latch off or autoretry (see the Latched and Autoretry Fault Management section). Slow-Comparator Startup Period The slow comparator is disabled during the startup period while the external MOSFETs are turning on. Disabling the slow comparator allows the device to ignore the higher-than-normal inrush current charging the board capacitors when a card is first plugged into a live backplane. Slow-Comparator Normal Operation After the startup period is complete, the slow comparator is enabled and the device enters normal operation. The comparator threshold voltage (VSC,TH) is adjustable from 25mV to 100mV. The slow-comparator response time is 3ms for a 1mV overdrive. The response time decreases to 100µs with a large overdrive. The variable-speed response time allows the MAX5930/MAX5931 to ignore low-amplitude momentary glitches, thus increasing system noise immunity. After an extended overcurrent condition, a fault is generated, STAT_ outputs are deasserted and the MOSFET gates are discharged with a 3mA pulldown current. Fast-Comparator Startup Period During the startup period, the fast comparator regulates the gate voltages to ensure that the voltage across the sense resistor does not exceed the startup fast-comparator threshold voltage (VSU,TH), VSU,TH is scaled to two times the slow-comparator threshold (VSC,TH). ______________________________________________________________________________________ 13 MAX5930/MAX5931 exceed VSU,TH. This effectively regulates the inrush current during startup. MAX5930/MAX5931 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers ON1 ON2 ON3 VUVLO (2.45V) IN1 VPWRRDY (0.95V) IN2 VPWRRDY (0.95V) IN3 VPWRRDY (0.95V) tD,UVLO * OUT1 * OUT2 * OUT3 *THE OUT_ DISCHARGE RATE IS A RESULT OF NATURAL DECAY OF THE LOAD RESISTANCE AND CAPACITANCE. Figure 5. Independent-Mode Timing Diagram 14 ______________________________________________________________________________________ Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers MAX5930/MAX5931 ON_ STAT_ SLOW COMPARATOR tSTART VDRIVE VOUT_ VGATE_ VOUT_ 3ms TURN-OFF TIME VGATE_ FAST COMPARATOR VTH 130µs CBOARD_ = LARGE VFC,TH 200ns RSENSE_ CBOARD_ = 0 VSC,TH ILOAD_ tON VFC,TH (2 x VSC,TH) SENSE VOLTAGE (VIN - VSENSE) Figure 6. Independent-Mode Startup Waveforms Figure 7. VariableSpeed/BiLevel Response Fast-Comparator Normal Operation In normal operation, if the load current reaches the fastcomparator threshold, a fault is generated, STAT_ is deasserted, and the MOSFET gates are discharged with a strong 50mA pulldown current. This happens in the event of a serious current overload or a dead short. The fast-comparator threshold voltage (V FC,TH ) is scaled to two times the slow-comparator threshold (VSC,TH). This comparator has a fast response time of 200ns (Figure 7). Bringing all input supplies below the UVLO threshold for longer than tD,GF reinitiates tD,UVLO and the startup period, tSTART. See Figure 8 for an example of automatic turn-on function. Undervoltage Lockout (UVLO) The UVLO prevents the MAX5930/MAX5931 from turning on the external MOSFETs until one input voltage exceeds the UVLO threshold (2.45V) for tD,UVLO. The MAX5930/MAX5931 use power from the highest input voltage rail for the charge pumps. This allows for more efficient charge-pump operation. The highest VIN_ is provided as an output at BIAS. The UVLO protects the external MOSFETs from an insufficient gate-drive voltage. tD,UVLO ensures that the board is fully inserted into the backplane and that the input voltages are stable. The MAX5930/MAX5931 includes a UVLO glitch filter (tD,GF) to reject all input voltage noise and transients. Latched and Autoretry Fault Management The MAX5930 can be configured to either latch the external MOSFETs off or to autoretry (see Table 2). Toggling ON_ below 0.875V for at least 100µs clears the MAX5930/MAX5931 (LATCH = FLOAT) fault and reinitiates the startup period. Similarly, the MAX5930/ MAX5931 (LATCH = GND) turn the external MOSFETs off when an overcurrent fault is detected, then automatically restart after the autoretry delay that is internally set to 64 times tSTART. Status Outputs (STAT_) The status (STAT_) outputs are open-drain outputs that assert when hot swap is successful and tSTART has elapsed. STAT_ deasserts if ON_ is low or if the channel is turned off for any fault condition. The polarity of the STAT_ outputs is selected using POL for the MAX5930 (see Table 3). Tables 4 and 5 contain the MAX5930/MAX5931 truth tables. ______________________________________________________________________________________ 15 MAX5930/MAX5931 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers Table 2. Selecting Fault-Management Mode (MAX5930) LATCH FAULT MANAGEMENT Floating Fault condition latches MOSFETs off Low Autoretry mode BACKPLANE REMOVABLE CARD V1 V2 V3 Table 3. Selecting STAT_ Polarity (MAX5930) POL STAT_ Low Asserts low Floating Asserts high (open-drain) ON1 ON1 ON2 ON2 ON3 ON3 Applications Information Component Selection N-Channel MOSFETs Select the external MOSFETs according to the application’s current levels. Table 6 lists recommended components. The MOSFET’s on-resistance (R DS(ON) ) should be chosen low enough to have a minimum voltage drop at full load to limit the MOSFET power dissipation. High RDS(ON) causes output ripple if there is a pulsating load. Determine the device power rating to accommodate a short-circuit condition on the board at startup and when the device is in autoretry mode (see the MOSFET Thermal Considerations section). Using these devices in latched mode allows the use of MOSFETs with lower power ratings. A MOSFET typically withstands single-shot pulses with higher dissipation than the specified package rating. Table 7 lists some recommended MOSFET manufacturers. Sense Resistor The slow-comparator threshold voltage is adjustable from 25mV to 100mV. Select a sense resistor that causes a drop equal to the slow-comparator threshold voltage at a current level above the maximum normal operating current. Typically, set the overload current at 1.2 to 1.5 times the full load current. The fast-comparator threshold is two times the slow-comparator threshold in normal operating mode. Choose the senseresistor power rating to be greater than or equal to 2 x (IOVERLOAD) x VSC,TH. Table 7 lists some recommended sense-resistor manufacturers. 16 MAX5930 MAX5931 GND GND Figure 8. Automatic Turn-On When Input Voltages are Above their Respective Undervoltage Lockout Threshold (Provided tD,UVLO Requirement is Met) Slow-Comparator Threshold, RLIM (MAX5930) The slow-comparator threshold voltage is adjustable from 25mV to 100mV, allowing designers to fine-tune the current-limit threshold for use with standard-value sense resistors. Low slow-comparator thresholds allow for increased efficiency by reducing the power dissipated by the sense resistor. Furthermore, the low 25mV slow-comparator threshold is beneficial when operating with supply rails down to 1V because it allows a small percentage of the overall output voltage to be used for current sensing. The VariableSpeed/BiLevel fault protection feature offers inherent system immunity against load transients and noise. This allows the slow-comparator threshold to be set close to the maximum normal operating level without experiencing nuisance faults. To adjust the slow-comparator threshold, calculate RLIM as follows: V − 25mV RLIM = TH 7.5µA where VTH is the desired slow-comparator threshold voltage. Shorting LIM_ to GND sets VTH to 25mV. Do not leave LIM_ open. ______________________________________________________________________________________ Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers MAX5930/MAX5931 Table 4. Status Output Truth Table: Voltage-Tracking and Power-Sequencing Modes CHANNEL 1 FAULT PART CHANNEL 2 FAULT CHANNEL 3 FAULT STAT1/ GATE1* STAT2/ GATE2* STAT3/ GATE3* Yes X X L/OFF L/OFF L/OFF X Yes X L/OFF L/OFF L/OFF X X Yes L/OFF L/OFF L/OFF L/OFF MAX5930 (POL = 1), MAX5931H X X X L/OFF L/OFF No No No H/ON H/ON H/ON Yes X X H/OFF H/OFF H/OFF X Yes X H/OFF H/OFF H/OFF X X Yes H/OFF H/OFF H/OFF X X X H/OFF H/OFF H/OFF No No No L/ON L/ON L/ON MAX5930 (POL = 0), MAX5931L *L = Low, H = High. Table 5. Status Output Truth Table: Independent Mode CHANNEL 1 FAULT CHANNEL 2 FAULT CHANNEL 3 FAULT STAT1/ GATE1 STAT2/ GATE2 STAT3/ GATE3 Yes Yes Yes Yes Yes No Unasserted/OFF Unasserted/OFF Unasserted/OFF Unasserted/OFF Unasserted/OFF Yes No Yes Unasserted/OFF Asserted/ON Asserted/ON Unasserted/OFF Yes No No Unasserted/OFF Asserted/ON Asserted/ON No Yes Yes Asserted/ON Unasserted/OFF Unasserted/OFF No Yes No Asserted/ON Unasserted/OFF Asserted/ON No No Yes Asserted/ON Asserted/ON Unasserted/OFF No No No Asserted/ON Asserted/ON Asserted/ON Note: STAT_ is asserted when hot swap is successful and tON has elapsed. STAT_ is unasserted during a fault. Table 6. Recommended N-Channel MOSFETs PART NUMBER MANUFACTURER IRF7413 IRF7401 International Rectifier MMSF3300 20mΩ, 8-pin SO, 30V Motorola FDS6670A FDB8030L 30mΩ, 8-pin SO, 20V 14mΩ, D2PAK, 50V MTB60N05H ND8426A 22mΩ, 8-pin SO, 20V 6mΩ, D2PAK, 20V IRL3502S MMSF5N02H DESCRIPTION 11mΩ, 8-pin SO, 30V 10mΩ, 8-pin SO, 30V Fairchild 13.5mΩ, 8-pin SO, 20V 4.5mΩ, D2PAK, 30V ______________________________________________________________________________________ 17 MAX5930/MAX5931 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers Table 7. Component Manufacturers COMPONENT Sense Resistors MOSFETs MANUFACTURER WEBSITE 402-562-3131 www.vishay.com IRC 704-264-8861 www.irctt.com Fairchild 888-522-5372 www.fairchildsemi.com International Rectifier 310-233-3331 www.irf.com Motorola 602-224-3576 www.mot-sps.com/ppd Setting the Startup Period, RTIM The startup period (tSTART) is adjustable from 0.4ms to 50ms. The adjustable startup period feature allows systems to be customized for MOSFET gate capacitance and board capacitance (CBOARD). The startup period is adjusted with a resistor connected from TIM to GND (RTIM). RTIM must be between 4kΩ and 500kΩ. The startup period has a default value of 9ms when TIM is left floating. Calculate RTIM with the following equation: t START RTIM = 128 × 800pF where tSTART is the desired startup period. Startup Sequence There are two ways of completing the startup sequence. Case A describes a startup sequence that slowly turns on the MOSFETs by limiting the gate charge. Case B uses the current-limiting feature and turns on the MOSFETs as fast as possible while still preventing a high inrush current. The output voltage ramp-up time (tON) is determined by the longer of the two timings, case A and case B. Set the startup timer (tSTART) to be longer than tON to guarantee enough time for the output voltage to settle. Case A: Slow Turn-On (Without Current Limit) There are two ways to turn on the MOSFETs without reaching the fast-comparator current limit: • If the board capacitance (C BOARD) is small, the inrush current is low. • If the gate capacitance is high, the MOSFETs turn on slowly. In both cases, the turn-on time is determined only by the charge required to enhance the MOSFET. The small 100µA gate-charging current effectively limits the output voltage dV/dt. Connecting an external capacitor between GATE and GND extends the turnon time. The time required to charge/discharge a MOSFET is as follows: 18 PHONE Dale-Vishay t= CGATE × ∆VGATE + QGATE IGATE where: C GATE is the external gate to ground capacitance (Figure 9), ∆VGATE is the change in gate charge, QGATE is the MOSFET total gate charge, IGATE is the gate-charging/discharging current. In this case, the inrush current depends on the MOSFET gate-to-drain capacitance (CRSS) plus any additional capacitance from GATE to GND (CGATE), and on any load current (ILOAD) present during the startup period. IINRUSH = CBOARD × IGATE + ILOAD CRSS + CGATE Example: Charging and discharging times using the Fairchild FDB7030L MOSFET If VIN1 = 5V then GATE1 charges up to 10.4V (VIN1 + VDRIVE), therefore ∆VGATE = 10.4V. The manufacturer’s data sheet specifies that the FDB7030L has approximately 60nC of gate charge and CRSS = 600pF. The MAX5930/MAX5931 have a 100µA gate charging current and a 3mA/50mA normal/strong discharging current. CBOARD = 6µF and the load does not draw any current during the startup period. With no gate capacitor, the inrush current, charge, and discharge times are: 6µF × 100µA + 0 = 1A 600pF + 0 0 × 10.4V + 60nC t CHARGE = = 0.6ms 100µA 0 × 10.4V + 60nC tDISCHARGE(NORMAL) = = 0.02ms 3mA 0 × 10.4V + 60nC = 1.2µs tDISCHARGE(STRONG) = 50mA IINRUSH = ______________________________________________________________________________________ Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers VOUT_ VIN CBOARD RPULLUP R1 SENSE_ IN_ GATE_ CGATE IN_ SENSE_ GATE_ ON_ STAT_ MAX5930 MAX5931 R2 MAX5930 MAX5931 VTURN-ON - (R2 x R1) VON, TH R2 ON_ GND Figure 9. Operating with an External Gate Capacitor Figure 10. Adjustable Undervoltage Lockout With a 22nF gate capacitor, the inrush current, charge, and discharge times are: under this condition, an external gate capacitor is not required. 6µF × 100µA + 0 = 26.5mA 600pF + 22nF 22nF × 10.4V + 60nC t CHARGE = = 2.89ms 100µA 22nF × 10.4V + 60nC tDISCHARGE(NORMAL) = = 0.096ms 3mA 22nF × 10.4V + 60nC = 5.8µs tDISCHARGE(STRONG) = 50mA IINRUSH = Case B: Fast Turn-On (With Current Limit) In applications where the board capacitance (CBOARD) is high, the inrush current causes a voltage drop across R SENSE that exceeds the startup fast-comparator threshold. The fast comparator regulates the voltage across the sense resistor to VFC,TH. This effectively regulates the inrush current during startup. In this case, the current charging CBOARD can be considered constant and the turn-on time is: ON Comparators The ON comparators control the on/off function of the MAX5930/MAX5931. ON_ is also used to reset the fault latch (latch mode). Pull VON_ low for 100µs, tUNLATCH, to reset the shutdown latch. ON_ also programs the UVLO threshold (see Figure 10). A resistive-divider between VIN_, VON_, and GND sets the user-programmable turn-on voltage. In power-sequencing mode, an RC circuit can be used at ON_ to set the delay timing (see Figure 11). Using the MAX5930/MAX5931 on the Backplane Using the MAX5930/MAX5931 on the backplane allows multiple cards with different input capacitance to be inserted into the same slot even if the card does not have on-board hot-swap protection. The startup period can be triggered if IN_ is connected to ON_ through a trace on the card (Figure 12). Input Transients C × VIN × RSENSE t ON = BOARD VFC,TH The maximum inrush current in this case is: IINRUSH = VFC,TH RSENSE Figure 6 shows the waveforms and timing diagrams for a startup transient with current regulation (see the Typical Operating Characteristics). When operating The voltage at IN1, IN2, or IN3 must be above VUVLO during inrush and fault conditions. When a short-circuit condition occurs on the board, the fast-comparator trips cause the external MOSFET gates to be discharged at 50mA according to the mode of operation (see the Mode section). The main system power supply must be able to sustain a temporary fault current, without dropping below the UVLO threshold of 2.45V, until the external MOSFET is completely off. If the main system power supply collapses below UVLO, the MAX5930/MAX5931 force the device to restart once the supply has recovered. The MOSFET is turned off in a very short time resulting in a high di/dt. The ______________________________________________________________________________________ 19 MAX5930/MAX5931 RSENSE_ VIN_ MAX5930/MAX5931 Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers RSENSEY Q1 VY OUTY CBOARDY INY R1 ON VEN SENSEY GATEY ON OFF MAX5930 MAX5931 C1 GND GND INZ SENSEZ GATEZ OUTZ VZ Q2 RSENSEZ VEN CBOARDZ (V VEN VONZ, TH (V VEN ) EN - VONY, TH t1 = -R1C1 ln VON VONY, TH VY ) EN - VONZ, TH t2 = -R1C1 ln VZ ( VV tDELAY = -R1C1 ln t0 t1 ) EN - VONY, TH EN - VONZ, TH t2 tDELAY Figure 11. Power Sequencing: Channel Z Turns On tDELAY After Channel Y backplane delivering the power to the external card must have low inductance to minimize voltage transients caused by this high di/dt. MOSFET Thermal Considerations During normal operation, the external MOSFETs dissipate little power. The MOSFET RDS(ON) is low when the MOSFET is fully enhanced. The power dissipated in normal operation is P D = I LOAD 2 x R DS(ON) . The most power dissipation occurs during the turn-on and turn-off transients when the MOSFETs are in their linear regions. By taking into consideration the worst-case scenario of a continuous short-circuit fault, consider these two cases: 1) The single turn-on with the device latched after a fault: MAX5930/MAX5931 (LATCH = high or floating). 20 2) The continuous autoretry after a fault: MAX5930/ MAX5931 (LATCH = low). MOSFET manufacturers typically include the package thermal resistance from junction to ambient (RθJA) and thermal resistance from junction to case (RθJC), which determine the startup time and the retry duty cycle (d = tSTART/(tSTART + tRETRY). Calculate the required transient thermal resistance with the following equation: Z θJA(MAX) ≤ TJMAX − TA VIN × ISTART where ISTART = VSU,TH / RSENSE. ______________________________________________________________________________________ Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers HIGH-CURRENT PATH POWER SUPPLY VIN VOUT CBOARD IN_ SENSE_ GATE_ SENSE RESISTOR MAX5930 MAX5931 ON_ MAX5930 MAX5931 Figure 12. Using the MAX5930/MAX5931 on a Backplane Layout Considerations To take full tracking advantage of the switch response time to an output fault condition, it is important to keep all traces as short as possible and to maximize the high-current trace dimensions to reduce the effect of undesirable parasitic inductance. Place the MAX5930/MAX5931 close to the card’s connector. Use a ground plane to minimize impedance and inductance. Minimize the current-sense resistor trace length (<10mm), and ensure accurate current sensing with Kelvin connections (Figure 13). When the output is short circuited, the voltage drop across the external MOSFET becomes large. Hence, the power dissipation across the switch increases, as does the die temperature. An efficient way to achieve good power dissipation on a surface-mount package is to lay out two copper pads directly under the MOSFET package on both sides of the board. Connect the two pads to the ground plane through vias, and use enlarged copper mounting pads on the topside of the board. Figure 13. Kelvin Connection for the Current-Sense Resistors Pin Configurations (continued) TOP VIEW ON2 1 20 MODE ON1 2 19 ON3 IN1 3 18 IN2 17 SENSE2 SENSE1 4 GATE1 5 MAX5931 16 GATE2 STAT1 6 15 IN3 STAT2 7 14 SENSE3 TIM 8 13 GATE3 LATCH 9 12 GND STAT3 10 11 BIAS QSOP ______________________________________________________________________________________ 21 MAX5930/MAX5931 BACKPLANE REMOVABLE CARD WITH NO HOT-INSERTION PROTECTION Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers BACKPLANE REMOVABLE CARD RSENSE1 Q1 V1 RSENSE2 V2 RSENSE3 ON3 STAT3 RLIM** BIAS TIM RLIM3** MODE POL* LATCH* RLIM2** LIM3* RLIM1** LIM2* GND STAT1 STAT2 MAX5930 MAX5931 LIM1* GND GATE2 ON3 OUT3 GATE3 ON2 SENSE3 SENSE2 SENSE1 IN3 IN2 IN1 ON1 ON2 OUT2 Q3 V3 ON1 OUT1 Q2 GATE1 MAX5930/MAX5931 Typical Operating Circuit 1nF 16V *MAX5930 ONLY. **OPTIONAL COMPONENT. Selector Guide CURRENT LIMIT FAULT MANAGEMENT MAX5930EEG PART Programmable Selectable Selectable STAT_ POLARITY MAX5931LEEP Fixed Selectable Asserted Low MAX5931HEEP Fixed Selectable Asserted High (Open-Drain) Chip Information TRANSISTOR COUNT: 7704 PROCESS: BiCMOS 22 ______________________________________________________________________________________ Low-Voltage, Triple, Hot-Swap Controllers/ Power Sequencers/Voltage Trackers QSOP.EPS PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 E 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 23 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX5930/MAX5931 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)