19-2238; Rev 2; 11/03 KIT ATION EVALU E L B A IL AVA Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers 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 MAX5904 family of hot-swap controllers prevents 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 completed, two on-chip comparators provide VariableSpeed/BiLevel™ protection against short-circuit and overcurrent faults, as well as immunity against system noise and load transients. In the event of a fault condition, the load is disconnected. The MAX5905/MAX5907/MAX5909 must be unlatched after a fault, and the MAX5904/MAX5906/MAX5908 automatically restart after a fault. The MAX5904 family offers a variety of options to reduce component count and design time. All devices integrate an on-board charge pump to drive the gates of low-cost, external N-channel MOSFETs. The devices offer integrated features like startup current regulation and current glitch protection to eliminate external timing resistors and capacitors. The MAX5906–MAX5909 provide an opendrain status output, an adjustable startup timer, an adjustable current limit, an uncommitted comparator, and output undervoltage/overvoltage monitoring. The MAX5904/MAX5905 are available in 8-pin SO packages. The MAX5906–MAX5909 are available in spacesaving 16-pin QSOP packages. Features ♦ Safe Hot Swap for +1V to +13.2V Power Supplies Requires One Input ≥ 2.7V ♦ ♦ ♦ ♦ Low 25mV Default Current-Limit Threshold Inrush Current Regulated at Startup Circuit Breaker Function Adjustable Circuit Breaker/Current-Limit Threshold ♦ VariableSpeed/BiLevel Circuit-Breaker Response ♦ Auto-Retry or Latched Fault Management ♦ On/Off Sequence Programming ♦ Status Output Indicates Fault/Safe Condition ♦ Output Undervoltage and Overvoltage Monitoring and/or Protection Ordering Information PART TEMP RANGE MAX5904ESA* -40°C to +85°C 8 SO 0°C to +85°C 8 SO -40°C to +85°C 8 SO MAX5904USA MAX5905ESA* MAX5905USA 0°C to +85°C MAX5906EEE* 16 QSOP 0°C to +85°C 16 QSOP -40°C to +85°C 16 QSOP 0°C to +85°C 16 QSOP -40°C to +85°C 16 QSOP MAX5906UEE MAX5907EEE* MAX5907UEE MAX5908EEE* MAX5908UEE MAX5909EEE* Basestation Line Cards Network Switches or Routers 0°C to +85°C 16 QSOP -40°C to +85°C 16 QSOP 0°C to +85°C 16 QSOP MAX5909UEE *Contact factory for availability. Pin Configurations TOP VIEW IN1 1 SENSE1 2 Solid-State Circuit Breaker Power-Supply Sequencing Hot Plug-In Daughter Cards RAID 8 SO -40°C to +85°C Applications PCI-Express Applications PIN-PACKAGE GATE1 3 MAX5904 MAX5905 GND 4 8 IN2 7 SENSE2 6 GATE2 5 ON NARROW SO Pin Configurations continued at end of data sheet. VariableSpeed/BiLevel is a trademark of Maxim Integrated Products, Inc. Selector Guide and Typical Operating Circuits appear at end of data sheet. ________________________________________________________________ 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 MAX5904–MAX5909 General Description The MAX5904–MAX5909 dual hot-swap controllers provide complete protection for dual-supply systems. These devices hot swap two supplies ranging from +1V to +13.2V, provided one supply is at or above 2.7V, allowing the safe insertion and removal of circuit cards into live backplanes. MAX5904–MAX5909 Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers ABSOLUTE MAXIMUM RATINGS IN_ to GND...........................................................................+14V GATE_ to GND..........................................+0.3V to (VIN_ + 6.2V) ON, PGOOD, COMP+, COMPOUT, TIM to GND.......-0.3V to the higher of (VIN1 + 0.3V) and (VIN2 + 0.3V) SENSE_, MON_, LIM_ to GND ...................-0.3V to (VIN_ + 0.3V) Current into Any Pin .........................................................±50mA Continuous Power Dissipation (TA = +70°C) 8-Pin Narrow SO (derate 5.9mW/°C above +70°C) ......471mW 16-Pin QSOP (derate 8.3mW/°C above +70°C)............667mW Operating Temperature Ranges: MAX590_U_ _ .....................................................0°C to +85°C MAX590_E_ _ ...................................................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C 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 higher than +2.7V, VON = +2.7V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VIN1 = +5V, VIN2 = +3.3V, and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS POWER SUPPLIES IN_ Input Voltage Range Supply Current VIN_ IIN Other VIN = +2.7V IIN1 + IIN2 1.0 13.2 V 1.2 2.3 mA 25 27.5 CURRENT CONTROL MAX5904/MAX5905 Slow-Comparator Threshold (VIN - VSENSE) (Note 2) Slow-Comparator Response Time (Note 3) Fast-Comparator Threshold Fast-Comparator Response Time SENSE Input Bias Current VSC,TH MAX5906–MAX5909 tSCD TA = +25°C 22.5 TA = TMIN to TMAX 20.5 LIM = GND 22.5 25 27.5 80 100 125 RLIM = 300kΩ 27.5 1mV overdrive 3 ms 50mV overdrive 110 µs VSU,TH VIN_ - VSENSE_; during startup 2 x VSC, TH VFC,TH VIN_ - VSENSE_; normal operation 4 x VSC, TH tFCD IB SEN mV mV 10mV overdrive, from overload condition 260 ns VSEN_ = VIN_ 0.03 6 8 10.8 13.6 µA MOSFET DRIVER RTIM = 100kΩ Startup Period (Note 4) Average Gate Current tSTART IGATE RTIM = 4kΩ (minimum value) 0.35 0.45 0.55 TIM floating for MAX5906–MAX5909 fixed for MAX5904/MAX5905 5 9 14 Charging, VGATE = +5V, VIN = +10V (Note 5) 80 100 130 Weak discharge, during startup when current limit is active or when 0.4V < VON < 0.8V Strong discharge, triggered by a fault or when VON < 0.4V Gate Drive Voltage VDRIVE VGATE_ - VIN_, IGATE_ < 1µA ms µA 100 µA 3 mA 4.8 5.4 5.8 V 0.375 0.4 0.425 V mV ON COMPARATOR Fast Pulldown ON Threshold 2 VONFP,TH Low to high Hysteresis 25 _______________________________________________________________________________________ Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers (VIN_ = +1V to +13.2V provided at least one supply is higher than +2.7V, VON = +2.7V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VIN1 = +5V, VIN2 = +3.3V, and TA = +25°C.) (Note 1) PARAMETER SYMBOL Channel 1 ON Threshold VON1,TH Channel 2 ON Threshold VON2,TH CONDITIONS Low to high MIN TYP MAX 0.80 0.825 0.85 1.95 25 2.025 Hysteresis Low to high Hysteresis ON Propagation Delay tON 10mV overdrive ON Input Bias Current IBON VIN1 = VIN2 = +13.2V 0.03 VON > 4.5V 100 0.03 VON = 4V ON Pulse Width Low tUNLATCH To unlatch after a latched fault V mV 2.07 25 50 VON < 4.5V UNITS V mV µs µA 1 100 µs DIGITAL OUTPUT (PGOOD) Output Leakage Current VPGOOD = 13.2V Output Voltage Low VOL tPGDLY PGOOD Delay 1 ISINK = 1mA 0.4 After tSTART, MON_ = VIN_ 0.75 µA V ms OUTPUT VOLTAGE MONITORS (MON1, MON2) MON_ Trip Threshold VMON_ Overvoltage 657 687 707 Undervoltage 513 543 563 MON_ Glitch Filter MON_ Input Bias Current VMON_ = 600mV mV 20 µs 0.03 µA UNDERVOLTAGE LOCKOUT (UVLO) UVLO Threshold VUVLO Startup is initiated when this threshold is reached by VIN1 or VIN2, VON > 0.8V, VIN_ increasing 2.1 Hysteresis UVLO Glitch Filter Reset Time UVLO to Startup Delay 2.4 2.67 100 VIN_ = 0V, to unlatch after a fault 100 tD,UVLO VIN_ step from 0 to 2.8V 20 tRETRY Delay time to restart after a fault shutdown MAX5904/MAX5906/MAX5908 V mV µs 37.5 60 ms SHUTDOWN RESTART Auto-Retry Delay 64 x tSTART ms UNCOMMITTED COMPARATOR INC+ Trip Threshold Voltage VC,TH Propagation Delay OUTC Voltage Low VOL INC+ Bias Current OUTC Leakage Current IOUTC Low to high 1.206 1.236 Hysteresis 10 10mV overdrive 50 ISINK = 1mA 1.266 V mV µs 0.4 V VINC+ = 5V 0.02 1 µA VOUTC = 13.2V 0.02 1 µA Note 1: Limits are 100% tested at TA = +25°C and +85°C. Limits at 0°C and -40° are guaranteed by characterization and are not production tested. Note 2 The MAX5906–MAX5909 slow-comparator threshold is adjustable. VSC,TH = RLIM x 0.25µA + 25mV (see Typical Operating Characteristics). Note 3: The current-limit slow-comparator response time is weighted against the amount of overcurrent; the higher the overcurrent condition, the faster the response time. See Typical Operating Characteristics. Note 4: 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. _______________________________________________________________________________________ 3 MAX5904–MAX5909 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, VIN1 = +5V, VIN2 = +3.3V, TA = +25°C, unless otherwise noted. Channels 1 and 2 are identical in performance. Where characteristics are interchangeable, channels 1 and 2 are referred to as X and Y.) 1.8 1.6 IINX 0.8 0.6 IINY 0.4 8 10 12 VINY = 5.0V A) VON = 3.3V B) VON = 1.5V C) VON = 0V 14 0.2 2 4 6 8 10 12 -40 14 GATE CHARGE CURRENT vs. TEMPERATURE 140 VINX = 13.2V 120 VINX = 5V 100 VINX = 1V 80 60 40 180 20 4 6 8 10 12 14 VINX = 13.2V 140 VINX = 5V 120 100 80 VINX = 1V 60 40 VON = VINY = 2.7V VGATEX = 0V 20 0 2 160 0 0 5 10 20 15 -40 -15 10 35 60 VINX (V) VGATEX (V) TEMPERATURE (°C) GATE WEAK DISCHARGE CURRENT vs. GATE VOLTAGE GATE WEAK DISCHARGE CURRENT vs. TEMPERATURE GATE STRONG DISCHARGE CURRENT vs. GATE VOLTAGE 120 100 VINX = 1V 60 40 20 5 10 VGATEX (V) 15 160 VINX = 5V VINX = 13.2V 140 120 100 VINX = 1V 80 60 40 VINY = 2.7V VGATEX = VINX + 6.2V 20 VINY = 2.7V 0 VON = 0.6V 180 VON = 0V VINX = 13.2V VINX = 5V 5 85 4 3 2 VINX = 1V 1 VINY = 2.7V VGATEX = VINX + 6.2V 0 0 20 6 GATE DISCHARGE CURRENT (mA) VINX = 13.2V VINX = 5V 200 MAX5904 toc08 VON = 0.6V GATE DISCHARGE CURRENT (µA) MAX5904 toc07 200 85 MAX5904 toc06 160 200 GATE CHARGE CURRENT (µA) MAX5904 toc05 VON = VINY = 2.7V 180 GATE CHARGE CURRENT (µA) MAX5904 toc04 200 0 0 60 GATE CHARGE CURRENT vs. GATE VOLTAGE VINY = 2.7V 80 35 GATE DRIVE VOLTAGE vs. INPUT VOLTAGE 1 140 10 TEMPERATURE (°C) 2 160 -15 VINX (V) 3 180 IIN2 0.4 0 0 4 0 IIN1 VINX (V) 5 GATE DRIVE VOLTAGE (V) 0.6 0.4 6 4 0.8 0 6 1.0 0.6 0.2 4 1.2 0.8 0 2 B 1.0 0.2 0 1.4 C 1.2 IIN (mA) IIN (mA) 1.0 IIN1 + IIN2 1.6 A 1.4 1.2 VON = VIN1 1.8 MAX5904 toc09 IINX + IINY 1.4 2.0 MAX5904 toc02 VINY = VON = 2.7V 1.6 IIN (mA) 2.0 MAX5904 toc01 2.0 1.8 SUPPLY CURRENT vs. TEMPERATURE TOTAL SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX5904 toc03 SUPPLY CURRENT vs. SUPPLY VOLTAGE GATE DISCHARGE CURRENT (µA) MAX5904–MAX5909 Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers -40 -15 10 35 TEMPERATURE (°C) 60 85 0 5 10 VGATEX (V) _______________________________________________________________________________________ 15 20 Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers SLOW-COMP. THRESHOLD 1 TURN-OFF TIME (ms) VINX = 13.2V VINX = 5V 3 VON = 0V VINY = 2.7V VGATEX = VINX + 6.2V 2 VINX = 1V TURN-OFF TIME (ms) 5 10 MAX5904 toc11 10 MAX5904 toc10 FAST-COMP. THRESHOLD 0.1 0.01 SLOW-COMP. THRESHOLD 1 0.001 1 0 0.1 0.0001 -40 -15 10 35 60 85 0 25 50 75 20 25 30 35 40 45 50 55 60 65 70 75 80 100 125 150 175 200 TEMPERATURE (°C) VIN - VSENSE (mV) VIN - VSENSE (mV) SLOW-COMPARATOR THRESHOLD vs. RLIM STARTUP PERIOD vs. RTIM TURN-OFF TIME SLOW-COMPARATOR FAULT 60 MAX5904 toc13 120 100 MAX5904 toc15 MAX5904 toc14 GATE DISCHARGE CURRENT (mA) 6 4 TURN-OFF TIME vs. SENSE VOLTAGE (EXPANDED SCALE) TURN-OFF TIME vs. SENSE VOLTAGE MAX5904 toc12 GATE STRONG DISCHARGE CURRENT vs. TEMPERATURE 50 tSTART (ms) VSC, TH (mV) 40 VPGOOD 5V/div tSCD 0V 80 MAX5904–MAX5909 Typical Operating Characteristics (continued) (Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, VIN1 = +5V, VIN2 = +3.3V, TA = +25°C, unless otherwise noted. Channels 1 and 2 are identical in performance. Where characteristics are interchangeable, channels 1 and 2 are referred to as X and Y.) 0V 26mV STEP 30 VSENSE - VIN 100mV/div 40 20 VGATE 5V/div 20 10 60 0 0V 0 0 100 200 300 400 0 100 200 RLIM (kΩ) 300 400 500 600 1ms/div VIN = 5.0V RTIM (kΩ) TURN-OFF TIME FAST-COMPARATOR FAULT STARTUP WAVEFORMS FAST TURN-ON MAX5904 toc16 MAX5904 toc17 VON 2V/div VPGOOD 5V/div 0V tFCD VPGOOD 2V/div 0V IOUT 5A/div 125mV STEP VSENSE - VIN 100mV/div VOUT 5V/div VGATE 5V/div VGATE 5V/div 0V 400ns/div VIN = 5.0V 1ms/div VIN = 5.0V, RSENSE = 10mΩ, RTIM = 27kΩ, CBOARD = 1000µF _______________________________________________________________________________________ 5 MAX5904–MAX5909 Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers Typical Operating Characteristics (continued) (Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, VIN1 = +5V, VIN2 = +3.3V, TA = +25°C, unless otherwise noted. Channels 1 and 2 are identical in performance. Where characteristics are interchangeable, channels 1 and 2 are referred to as X and Y.) STARTUP WAVEFORMS SLOW TURN-ON AUTO-RETRY DELAY MAX5904 toc18 MAX5904 toc19 VON 2V/div VGATE 5V/div VPGOOD 2V/div IOUT 5A/div VOUT 5V/div VOUT 5V/div IOUT 5A/div VGATE 5V/div 1ms/div VIN = 5.0V, RSENSE = 10mΩ, RTIM = 47kΩ, CBOARD = 1000µF, CGATE = 22nF 40ms/div VIN = 5.0V, RSENSE = 10mΩ, RTIM = 47kΩ, CBOARD = 1000µF, RBOARD = 1.4Ω Pin Description PIN 6 MAX5904/ MAX5905 MAX5906– MAX5909 NAME FUNCTION — 1 PGOOD Open-Drain Status Output. High impedance when startup is complete and no faults are detected. Actively held low during startup and when a fault is detected. — 2 TIM 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. 1 3 IN1 Channel 1 Supply Input. Connect to a supply voltage from 1V to 13.2V. Connect a 0.1µF ceramic bypass capacitor from IN1 to GND to filter high-frequency noise. 2 4 SENSE1 Channel 1 Current-Sense Input. Connect RSENSE1 from IN1 to SENSE1. 3 5 GATE1 Channel 1 Gate-Drive Output. Connect to gate of external N-channel MOSFET. 4 6 GND Ground 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. — 7 LIM1 — 8 MON1 Channel 1 Output Voltage Monitor. Window comparator input. Connect through a resistive-divider from OUT1 to GND to set the channel 1 overvoltage and undervoltage thresholds. Connect to IN1 to disable. — 9 MON2 Channel 2 Output Voltage Monitor. Window comparator input. Connect through a resistive-divider from OUT2 to ground to set the channel 2 overvoltage and undervoltage thresholds. Connect to IN2 to disable. _______________________________________________________________________________________ Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers PIN MAX5904/ MAX5905 MAX5906– MAX5909 NAME FUNCTION — 10 LIM2 5 11 ON 6 12 GATE2 Channel 2 Gate-Drive Output. Connect to gate of external N-channel MOSFET. 7 13 SENSE2 Channel 2 Current-Sense Input. Connect RSENSE2 from IN2 to SENSE2. 8 14 IN2 — 15 INC+ Uncommitted Comparator Noninverting Input — 16 OUTC Uncommitted Comparator Open-Drain Output. Actively held low when VINC+ is less than 1.236V. 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. On Comparator Input Channel 2 Supply Input. Connect to a supply voltage from 1V to 13.2V. Connect a 0.1µF ceramic bypass capacitor from IN2 to GND to filter high-frequency noise. Detailed Description The MAX5904–MAX5909 are circuit breaker ICs for hotswap applications where a line card is inserted into a live backplane. These devices hot swap supplies ranging from +1V to +13.3V, provided one supply is at or above 2.7V. 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 MAX5904– MAX5909 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 two on-chip comparators. Figure 1 shows the MAX5906–MAX5909 functional diagram. The MAX5904/MAX5905 have a fixed startup period and current-limit threshold. The startup period and current-limit threshold of the MAX5906–MAX5909 can be adjusted with external resistors. Startup Period R TIM sets the duration of the startup period for the MAX5906–MAX5909 from 0.4ms to 50ms (see the Setting the Startup Period section). The duration of the startup period is fixed at 9ms for the MAX5904/ MAX5905. The startup period begins after the following three conditions are met: 1) VIN1 or VIN2 exceeds the UVLO threshold (2.4V) for the UVLO to startup delay (37.5ms). 2) VON exceeds the channel 1 ON threshold (0.825V). 3) The device is not latched or in its auto-retry delay. (See Latched and Auto-Retry Fault Management.) The MAX5904–MAX5909 limit the load current if an overcurrent fault occurs during startup. 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 typically 100µA and decreases with the increase of the gate voltage (see Typical Operating Characteristics). This allows the controller to slowly enhance the MOSFETs. If the fast comparator detects an overcurrent, the MAX5904–MAX5909 regulate the gate voltage to ensure that the voltage across the sense resistor does not exceed VSU,TH. This effectively regulates the inrush current during startup. Figure 2 shows the startup waveforms. PGOOD goes high impedance 0.75ms after the startup period if no fault condition is present. VariableSpeed/BiLevel Fault Protection VariableSpeed/BiLevel fault protection incorporates two comparators with different thresholds and response times to monitor the load current (Figure 9). 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 both MOSFET gates with a strong 3mA pulldown current in response to a fault condition. After a fault, _______________________________________________________________________________________ 7 MAX5904–MAX5909 Pin Description (continued) 8 OUT1 Q1 RSENSE1 MON1 GATE1 SENSE1 IN1 1.236V 3mA VSC, TH INC+ RLIM1 UVLO ON DEVICE CONTROL LOGIC TIMING OSCILLATOR BIAS AND REFERENCES 2.4V SLOW COMP. FAST COMP. 543mV N RTIM OUTC TIM STARTUP OSCILLATOR TO STARTUP LOGIC BLOCKS 0.4V PGOOD CHARGE PUMP OSCILLATOR 543mV 687mV 687mV 0.825V 100µA N CHARGE PUMP 100µA TO STARTUP LOGIC BLOCKS CURRENT CONTROL AND STARTUP LOGIC UVLO FAST DISCHARGE 2.025V 2.4V SLOW DISCHARGE CURRENT CONTROL AND STARTUP LOGIC SLOW COMP. FAST COMP. VFS, TH FAST DISCHARGE CHARGE PUMP VFS, TH RLIM2 MAX5906 MAX5907 MAX5908 MAX5909 LIM2 SLOW DISCHARGE LIM1 3mA VSC, TH MON2 GATE2 SENSE2 IN2 Q2 OUT2 RSENSE2 MAX5904–MAX5909 Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers Figure 1. MAX5906–MAX5909 Functional Diagram _______________________________________________________________________________________ Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers ON PGOOD tSTART + tPGDLY VGATE 4.8V TO 5.8V VOUT VTH VGATE VOUT CBOARD = LARGE VSU,TH Fast Comparator Normal Operation In normal operation, if the load current reaches the fastcomparator threshold, a fault is generated, PGOOD is pulled low, and the MOSFET gates are discharged with a strong 3mA pulldown current. This happens in the event of a serious current overload or a dead short. The fast-comparator threshold voltage (VFC,TH) is scaled to four times the slow-comparator threshold (VSC,TH). This comparator has a fast response time of 260ns (Figure 9). RSENSE CBOARD = 0 ILOAD tON Figure 2. Startup Waveforms PGOOD is pulled low, the MAX5905/MAX5907/ MAX5909 stay latched off and the MAX5904/MAX5906/ MAX5908 automatically restart. 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 fixed at 25mV for the MAX5904/MAX5905 and is adjustable from 25mV to 100mV for the MAX5906–MAX5909. The slow comparator response time decreases to a minimum of 110µs with a large overdrive voltage (Figure 9). Response time is 3ms for a 1mV overdrive. The variable speed response time allows the MAX5904–MAX5909 to ignore low-amplitude momentary glitches, thus increasing system noise immunity. After an extended overcurrent condition, a fault is generated, PGOOD is pulled low, and the MOSFET gates are discharged with a strong 3mA pulldown current. Undervoltage Lockout (UVLO) The undervoltage lockout prevents the MAX5904– MAX5909 from turning on the external MOSFETs until one input voltage exceeds the UVLO threshold (2.4V) for tD,UVLO. The MAX5904–MAX5909 use power from the higher input voltage rail for the charge pumps. This allows for more efficient charge-pump operation. 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. Any input voltage transient on both supplies below the UVLO threshold will reinitiate the tD,UVLO and the startup period. Latched and Auto-Retry Fault Management The MAX5905/MAX5907/MAX5909 latch the external MOSFETs off when a fault is detected. Toggling ON below 0.4V or one of the supply voltages below the UVLO threshold for at least 100µs clears the fault latch and reinitiates the startup period. Similarly, the MAX5904/MAX5906/MAX5908 turn the external MOSFETs off when a fault is detected then automatically restart after the auto-retry delay that is internally set to 64 times tSTART. During the auto-retry delay, toggling ON below 0.4V does not clear the fault. The auto-retry can be overridden causing the startup period to begin immediately by toggling one of the supply voltages below the UVLO threshold. Output Voltage Monitor The MAX5905–MAX5909 monitor the output voltages with the MON1 and MON2 window comparator inputs. These voltage monitors are enabled after the startup period. Once enabled, the voltage monitor detects a fault if V MON _ is less than 543mV or greater than 687mV. If an output voltage fault is detected PGOOD pulls low. When the MAX5906/MAX5907 detect an out- _______________________________________________________________________________________ 9 MAX5904–MAX5909 Fast Comparator Startup Period During the startup period the fast comparator regulates the gate voltage to ensure that the voltage across the sense resistor does not exceed VSU,TH. The startup fast-comparator threshold voltage (VSU,TH) is scaled to two times the slow-comparator threshold (VSC,TH). Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904–MAX5909 Timing Diagrams VON VON_,TH VGATE_ VOUT_ INTERNAL SIGNAL tSTART INTERNAL SIGNAL tPGDLY PGOOD Figure 3. Power-Up with ON Pin Control (At Least One VIN_ is > VUVLO) 10 ______________________________________________________________________________________ Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers OVERCURRENT CONDITION (VIN_ - VSENSE_ ≥ VSC_TH AND VIN_ - VSENSE_ < VFC_TH) tSCD IOUT VGATE_ DISCHARGE RATE DEPENDS ON OUTPUT LOADING VOUT_ PGOOD Figure 4. Power-Down when an Overcurrent Fault Occurs SHORT-CIRCUIT CONDITION (VIN_ - VSENSE_ ≥ VFC_TH) tFCD IOUT VGATE_ VOUT_ PGOOD Figure 5. Power-Down when a Short-Circuit Fault Occurs ______________________________________________________________________________________ 11 MAX5904–MAX5909 Timing Diagrams (continued) Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904–MAX5909 Timing Diagrams (continued) UV/OV CONDITION INTERNAL SIGNAL MON_ GLITCH FILTER, 20µS VGATE_ DISCHARGE RATE DEPENDS ON OUTPUT LOADING VOUT_ PGOOD Figure 6. Power-Down when an Undervoltage/Overvoltage Fault Occurs (MAX5906/MAX5907) UV/OV CONDITION INTERNAL SIGNAL MON_ GLITCH FILTER, 20µS VGATE_ VGATE_ AND VOUT_ STAY ON VOUT_ PGOOD Figure 7. Fault Report when an Undervoltage/Overvoltage Fault Occurs (MAX5908/MAX5909) 12 ______________________________________________________________________________________ Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers VIN_ VUVLO VGATE_ VOUT_ tD,UVLO INTERNAL SIGNAL tSTART INTERNAL SIGNAL tPGDLY PGOOD Figure 8. Power-Up with Undervoltage Lockout Delay (VON = 2.7V, the Other VIN_ is Below VUVLO) ______________________________________________________________________________________ 13 MAX5904–MAX5909 Timing Diagrams (continued) MAX5904–MAX5909 Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers put voltage fault on either MON1 or MON2, the fault is latched and both external MOSFET gates are discharged at 3mA. When the MAX5908/MAX5909 detect an output voltage fault the external MOSFET gates are not affected. The MAX5908/MAX5909 PGOOD goes high impedance when the output voltage fault is removed. The voltage monitors do not react to output glitches of less than 20µs. A capacitor from MON_ to GND increases the effective glitch filter time. Connect MON1 to IN1 and MON2 to IN2 to disable the output voltage monitors. Status Output (PGOOD) The status output is an open-drain output that pulls low in response to one of the following conditions: • Forced off (ON < 0.8V) • Overcurrent fault • Output voltage fault PGOOD goes high impedance 0.75ms after the device enters normal operation and no faults are present (Table 1). Applications Information Component Selection N-Channel MOSFET Select the external MOSFETs according to the application’s current levels. Table 2 lists some recommended components. The MOSFET’s on-resistance (RDS(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 automatic-retry mode (see MOSFET Thermal Considerations). Using the MAX5905/MAX5907/MAX5909 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 3 lists some recommended manufacturers and components. Sense Resistor The slow-comparator threshold voltage is set at 25mV for the MAX5904/MAX5905 and is adjustable from 25mV to 100mV for the MAX5906–MAX5909. Select a sense resistor that causes a drop equal to the slowcomparator 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 nominal load current. The fast-comparator threshold is four times the slow-comparator threshold in normal operating mode. Choose the sense resistor power rating to be greater than (IOVERLOAD)2 x VSC,TH. Slow-Comparator Threshold, RLIM The slow-comparator threshold voltage of the MAX5904/MAX5905 is fixed at 25mV and adjustable from 25mV to 100mV for the MAX5906–MAX5909. The adjustable slow-comparator threshold of the MAX5906–MAX5909 allows 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 Table 1. Status Output Truth Table DEVICE IN STARTUP PERIOD ON OVERCURRENT FAULT OVER/UNDERVOLTAGE FAULT PART IN RETRY-TIMEOUT PERIOD OR LATCHED OFF PGOOD Yes X X X X X Low X Yes X X X X Low X X Low X X X Low X X X Yes X X Low X X X X Yes X Low DEVICE IN UVLO DELAY PERIOD X X X X X Yes Low No No High No No No High-Z X = don’t care 14 ______________________________________________________________________________________ Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers PART NUMBER MANUFACTURER DESCRIPTION IRF7413 11mΩ, 8 SO, 30V International Rectifier IRF7401 22mΩ, 8 SO, 20V IRL3502S 6mΩ, D2PAK, 20V MMSF3300 20mΩ, 8 SO, 30V Motorola MMSF5N02H 30mΩ, 8 SO, 20V MTB60N05H 14mΩ, D2PAK, 50V FDS6670A 10mΩ, 8SO, 30V Fairchild NDS8426A 13.5mΩ, 8 SO, 20V FDB8030L 4.5mΩ, D2PAK, 30V faults. Typically, set the overload current at 1.2 to 1.5 times the nominal load current. To adjust the slow-comparator threshold calculate RLIM as follows: V − 25mV RLIM = TH 0.25µA where VTH is the desired slow-comparator threshold voltage. Setting the Startup Period, RTIM The startup period (tSTART) of the MAX5904/MAX5905 is fixed at 9ms, and adjustable from 0.4ms to 50ms for the MAX5906–MAX5909. The adjustable startup period of the MAX5906–MAX5909 systems can be customized for MOSFET gate capacitance and board capacitance (CBOARD). The startup period is adjusted with the resistance connected from TIM to GND (RTIM). RTIM must be between 4kΩ and 500kΩ. The MAX5906–MAX5909 startup period has a default value of 9ms when TIM is left floating. Calculate RTIM with the following equation: RTIM = t START 128 × 800pF 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 MAX5906– MAX5909 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 gate-charging current of 100µA effectively limits the output voltage dV/dt. Connecting an external capacitor between GATE and GND extends turn-on time. The time required to charge/discharge a MOSFET is as follows: t= CGATE × ∆VGATE + QGATE IGATE where: C GATE is the external gate to ground capacitance (Figure 4) ∆VGATE is the change in gate voltage 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. where tSTART is the desired startup period. Table 3. Component Manufacturers COMPONENT Sense Resistors MOSFETs MANUFACTURER PHONE WEBSITE Dale-Vishay 402-564-3131 www.vishay.com IRC 704-264-8861 www.irctt.com International Rectifier 310-233-3331 www.irf.com Fairchild 888-522-5372 www.fairchildsemi.com Motorola 602-244-3576 www.mot-sps.com/ppd ______________________________________________________________________________________ 15 MAX5904–MAX5909 Table 2. Recommended N-Channel MOSFETs MAX5904–MAX5909 Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers IINRUSH = CBOARD × IGATE + ILOAD Crss + CGATE t ON = CBOARD × VIN × RSENSE VSU,TH 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 MAX5904–MAX5909 have a 100µA gate-charging current and a 100µA weak discharging current or 3mA strong discharging current. CBOARD = 6µF and the load does not draw any current during the startup period. The maximum inrush current in this case is: With no gate capacitor the inrush current, charge, and discharge times are: The ON comparator controls the on/off function of the MAX5904–MAX5909. ON is the input to a precision three-level voltage comparator that allows individual control over channel 1 and channel 2. Drive ON high (> 2.025V) to enable channel 1 and channel 2. Pull ON low (<0.4V) to disable both channels. To enable channel 1 only, VON must be between the channel 1 ON threshold (0.825V) and the channel 2 ON threshold (2.025V). The device can be turned off slowly, reducing inductive kickback, by forcing ON between 0.4V and 0.825V until the gates are discharged. The ON comparator is ideal for power sequencing (Figure 11). 6µF × 100µA + 0 = 1A 600pF + 0 0 × 10.4V + 60nC t CHARGE = = 0.6ms 100µA IINRUSH = tDISCHARGE _ SLOW = tDISCHARGE _ FAST = 0 × 10.4V + 60nC = 0.6ms 100µA 0 × 10.4V + 60nC = 0.02ms 3mA With a 22nF gate capacitor the inrush current, charge, and discharge times are: 6µF × 100µA + 0 = 26.5mA 600pF + 22nF 22nF × 10.4V + 60nC t CHARGE = = 2.89ms 100µA IINRUSH = tDISCHARGE _ SLOW = tDISCHARGE _ FAST = 22nF × 10.4V + 60nC = 2.89ms 100µA 22nF × 10.4V + 60nC = 0.096ms 3mA 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 VSU,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: 16 IINRUSH = VSU,TH RSENSE Figures 2–8 show the waveforms and timing diagrams for a startup transient with current regulation. (See Typical Operating Characteristics.) When operating under this condition, an external gate capacitor is not required. ON Comparator Uncommitted Comparator The MAX5906–MAX5909 feature an uncommitted comparator that increases system flexibility. This comparator can be used for voltage monitoring, or for generating a power-on reset signal for on-card microprocessors (Figure 12). The uncommitted comparator output (OUTC) is open drain and is pulled low when the comparator input voltage (VINC+) is below its threshold voltage (1.236V). OUTC is high impedance when VINC+ is greater than 1.236V. Using the MAX5904–MAX5909 on the Backplane Using the MAX5904–MAX5909 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 13). Input Transients The voltage at IN1 or IN2 must be above the UVLO during inrush and fault conditions. When a short-circuit condition occurs on the board, the fast comparator trips ______________________________________________________________________________________ Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers SLOW COMPARATOR MOSFET Thermal Considerations TURN-OFF TIME 3ms FAST COMPARATOR 110µs 260ns VSC,TH 2) The continuous automatic retry after a fault (MAX5904/MAX5906/MAX5908) VFC,TH (4 x VSC,TH) 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 / tRETRY). Calculate the required transient thermal resistance with the following equation: SENSE VOLTAGE (VIN - VSENSE) Figure 9. VariableSpeed/BiLevel Response RSENSE VOUT VIN 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 PD = ILOAD2 x RDS(ON). The most power dissipation occurs during the turn-on and turnoff transients when the MOSFETs are in their linear regions. Take 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 (MAX5905/MAX5907/MAX5909) CBOARD RPULLUP −T T Z θJA(MAX ) ≤ JMAX A VIN × ISTART where ISTART = VSU,TH / RSENSE IN PGOOD SENSE GATE CGATE MAX5906 MAX5907 MAX5908 MAX5909 ON GND Figure 10. Operating with an External Gate Capacitor causing the external MOSFET gates to be discharged at 3mA. The main system power supply must be able to sustain a temporary fault current, without dropping below the UVLO threshold of 2.4V, until the external MOSFET is completely off. If the main system power supply collapses below UVLO, the MAX5904–MAX5909 will force the device to restart once the supply has recovered. The MOSFET is turned off in a very short 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 MAX5904– MAX5909 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 14). 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 top side of the board. See MAX5908 EV Kit. ______________________________________________________________________________________ 17 MAX5904–MAX5909 time resulting in a high di/dt. The backplane delivering the power to the external card must have low inductance to minimize voltage transients caused by this high di/dt. MAX5904–MAX5909 Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers RSENSE1 Q1 V1 OUT1 CBOARD1 IN1 R1 ON VEN SENSE1 GATE1 ON OFF MAX5904 MAX5905 C1 GND GND IN2 SENSE2 GATE2 OUT2 V2 Q2 RSENSE2 CBOARD2 VEN VON2, TH t1 = -R1C1 ln (V VEN t2 = -R1C1 ln (V VEN ) EN - VON1, TH VON VON1, TH V1 ) EN - VON2, TH V2 tDELAY = -R1C1 ln t0 t1 ( VV ) EN - VON1, TH EN - VON2, TH t2 TDELAY Figure 11. Power Sequencing: Channel 2 Turns On tDELAY After Channel 1 Chip Information TRANSISTOR COUNT: 3230 PROCESS: BiCMOS 18 ______________________________________________________________________________________ Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers IN SENSE GATE INC+ SENSE RESISTOR µP MAX5906–MAX5909 OUTC RESET MAX590_ Figure 12. Power-On Reset Figure 14. Kelvin Connection for the Current-Sense Resistors BACKPLANE REMOVABLE CARD WITH NO HOT-INSERTION PROJECTION Pin Configurations (continued) VOUT VIN CBOARD TOP VIEW 16 OUTC PGOOD 1 IN SENSE GATE TIM 2 15 INC+ IN1 3 MAX590_ SENSE1 4 ON GATE1 5 GND 6 14 IN2 MAX5906 MAX5907 MAX5908 MAX5909 LIM1 7 13 SENSE2 12 GATE2 11 ON 10 LIM2 MON1 8 9 MON2 QSOP Figure 13. Using the MAX5904–MAX5909 on a Backplane Selector Guide OUTPUT UNDERVOLTAGE/OVERVOLTAGE PROTECTION/MONITOR FAULT MANAGEMENT MAX5904ESA/MAX5904USA — Auto-Retry MAX5905ESA/MAX5905USA — Latched MAX5906EEE/MAX5906UEE Protection Auto-Retry MAX5907EEE/MAX5907UEE Protection Latched MAX5908EEE/MAX5908UEE Monitor Auto-Retry MAX5909EEE/MAX5909UEE Monitor Latched PART ______________________________________________________________________________________ 19 MAX5904–MAX5909 HIGH-CURRENT PATH VIN Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904–MAX5909 Typical Operating Circuits BACKPLANE REMOVABLE CARD RSENSE1 Q1 V1 OUT1 0.1µF CBOARD1 IN1 SENSE1 GATE1 ON ON MAX5904 MAX5905 GND GND IN2 SENSE2 GATE2 0.1µF OUT2 V2 Q2 RSENSE2 BACKPLANE CBOARD2 REMOVABLE CARD RSENSE1 Q1 V1 OUT1 * CBOARD1 0.1µF * IN1 SENSE1 GATE1 MON1 ON ON PGOOD STAT * TIM * LIM1 * LIM2 OUTC MAX5906 MAX5907 MAX5908 MAX5909 INC+ MON2 GND GND UNCOMMITTED COMPARATOR * IN2 SENSE2 GATE2 * 0.1µF OUT2 V2 RSENSE2 Q2 CBOARD2 *OPTIONAL 20 ______________________________________________________________________________________ Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers N E H INCHES MILLIMETERS MAX MIN 0.053 0.069 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS DIM A A1 B C e E H L 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D A B e C 0 -8 A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 REV. B 1 ______________________________________________________________________________________ 1 21 MAX5904–MAX5909 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.) Package Information (continued) (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.) QSOP.EPS MAX5904–MAX5909 Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers 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. 22 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.