19-5542; Rev 1; 4/11 TION KIT EVALUA BLE IL AVA A 2.7V to 18V, 7A, Hot-Swap Solution Features The MAX5976A/MAX5976B are integrated solutions for hot-swap applications requiring the safe insertion and removal of circuit line cards from a live backplane. The devices integrate a hot-swap controller, 24mI power MOSFET, and electronic circuit-breaker protection in a single package. The ICs are designed for protection of 2.7V to 18V supply voltages. S 2.7V to 18V Operating Voltage Range S 24mI Internal Power MOSFET S 7A Load Current Capability S No Sense Resistor Required S 10% Circuit-Breaker Threshold Accuracy S Adjustable Circuit-Breaker Current The devices provide inrush current control and shortcircuit detection during startup. During normal operation, the devices provide circuit-breaker protection against overload and short-circuit conditions. The circuit-breaker function disconnects the power to the load if the load current exceeds the circuit-breaker limit. The devices are factory-calibrated to deliver accurate overcurrent protection with Q10% accuracy. During a fault condition, the MAX5976A enters an autoretry mode while the MAX5976B latches off. Both versions feature a resistoradjustable variable speed circuit-breaker threshold and overtemperature protection. Additional features include power-good and fault indicator outputs. S Variable Speed Circuit-Breaker Response S Thermal Protection S Power-Good and Fault Outputs S Latch-Off or Automatic Retry Options S Drive-Present Signal Input S Active-Low and Active-High Enables Ordering Information The ICs are available in a 16-pin, 5mm x 5mm, TQFNEP package and fully specified over the -40C to +85C operating temperature range. Applications FAULT MANAGEMENT PART PIN PACKAGE MAX5976AETE+ 16 TQFN-EP* Autoretry MAX5976BETE+ 16 TQFN-EP* Latched Off Note: All devices are specified over the -40C to +85C operating temperature range. +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. RAID Systems Storage Bridge Bay Disk Drive Power Server I/O Cards Industrial Typical Application Circuit 2.7V TO 18V REMOVABLE CARD IN CIN OUT VIN TVS R1 PRESDET LOAD (7A) VPRESDET ON1 MAX5976A MAX5976B R2 RCB CB ON2 REG PG RON2 RPG CREG RFAULT FAULT 2.7V TO 6V GND P ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. MAX5976A/MAX5976B General Description MAX5976A/MAX5976B 2.7V to 18V, 7A, Hot-Swap Solution ABSOLUTE MAXIMUM RATINGS IN to GND...............................................................-0.3V to +20V CB to GND...............................................-0.3V to (VREG + 0.3V) ON1, REG to GND...................................................-0.3V to +6V OUT, ON2, PRESDET to GND................ -0.3V to the lower of (VIN + 0.3V) and +20V PG, FAULT to GND................................................-0.3V to +26V Continuous Power Dissipation (TA = +70NC) TQFN (derate 33.3mW/NC above +70NC) (Note 1)...2666.7mW Operating Ambient Temperature Range............ -40NC to +85NC Maximum Junction Temperature......................................+150NC Storage Temperature Range............................. -60NC to +150NC Lead Temperature (soldering, 10s).................................+300NC Soldering Temperature (reflow).......................................+260NC Note 1: As per JEDEC51 standard (multilayer board). 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. PACKAGE THERMAL CHARACTERISTICS (Note 2) TQFN Junction-to-Case Thermal Resistance (BJC)....................30NC/W Junction-to-Ambient Thermal Resistance (BJA)................ ...2NC/W Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. ELECTRICAL CHARACTERISTICS (VIN = 12V, VON1 = 2V, VON2 = VPRESDET = 0V, RCB = 40kI, TA = TJ = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 3) PARAMETER Input Supply Voltage Range Input Supply Current SYMBOL CONDITIONS VIN IIN Default Undervoltage Lockout VUVLO Default Undervoltage Lockout Hysteresis VUVLO_HYS MIN TYP MAX UNITS 18 V 5 7.5 mA 2.5 2.65 V 2.7 VON1 = 3V, no load, 7A current-limit threshold VIN rising, VON1 = VIN 2.35 0.1 ON1 Turn-On Threshold VON1_TH VON1 rising ON1 Turn-On Threshold Hysteresis VON1_HYS VON1 falling ON1 Input Bias Current ION1 1.17 1.21 V 1.25 0.1 VON1 = 0 to 5V -1 RCB = 40kI 6.3 V V +1 FA CURRENT LIMIT Circuit-Breaker Accuracy (At Startup) Slow-Comparator Response Time (Note 4) ICB,TH tSCD 7 7.7 RCB = 28.57kI 4.5 5 5.5 RCB = 20kI 3.15 3.5 3.85 RCB = 10kI 1.575 1.75 1.925 A 0.6% overcurrent 2.7 ms 30% overcurrent 200 Fs MOSFET Total On-Resistance RON 15 24 41 mI 0.4 V +1 FA LOGIC INPUTS (ON2, PRESDET) Low Voltage Input VIL 2.7V < VIN < 18V High Voltage Input VIH 2.7V < VIN < 18V 1.4 Input Current IIN VON2, VPRESDET = 0 to 6V -1 2 V 2.7V to 18V, 7A, Hot-Swap Solution (VIN = 12V, VON1 = 2V, VON2 = VPRESDET = 0V, RCB = 40kI, TA = TJ = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS OPEN-DRAIN OUTPUTS FAULT, PG Output Low Voltage VOL Low-impedance state, IFAULT = IPG = 5mA 0.4 V FAULT, PG Output High Leakage Current IOH High-impedance state, VFAULT = VPG = 16V 1 FA OUT Bias Current IOUT VON1 = GND 10 FA TIMING Automatic Restart Delay After Current-Limit Timeout tOFF PG Assertion Delay tPG ms 16 ms 0.9 x VIN V Thermal-Shutdown Threshold 150 NC Thermal-Shutdown Threshold Hysteresis 20 NC PG Threshold From VOUT > VPG 250 VPG VOUT = 12V THERMAL PROTECTION Note 3: All devices are 100% production tested at TA = +25C. Limits over temperature are guaranteed by design. Note 4: The current-limit slow-comparator response time is weighed against the amount of overcurrent so that the higher the overcurrent condition, the faster the response time. Typical Operating Characteristics (VIN = 12V, VON1 = 2V, RCB = 40k, VON2 = VPRESDET = 0V, TA = +25C, unless otherwise noted.) VIN = 12V 5.0 4.5 VIN = 5V -15 10 35 TEMPERATURE (C) 6 4 2 VIN = 12V 8 RCB = 39.3kI 6 RCB = 30.1kI MAX5976 toc03 8 10 RCB = 19.9kI 4 RCB = 10kI 2 VIN = 3V 4.0 -40 VIN = 12V CIRCUIT-BREAKER THRESHOLD (A) 5.5 10 MAX5976 toc02 MAX5976 toc01 VON1 = 2V CIRCUIT-BREAKER THRESHOLD (A) SUPPLY CURRENT (mA) 6.0 CIRCUIT-BREAKER THRESHOLD vs. TEMPERATURE CIRCUIT-BREAKER THRESHOLD vs. CIRCUIT-BREAKER RESISTANCE SUPPLY CURRENT vs. TEMPERATURE 60 85 0 10 15 20 25 RCB (kI) 30 35 40 0 -40 -15 10 35 60 85 TEMPERATURE (C) 3 MAX5976A/MAX5976B ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VIN = 12V, VON1 = 2V, RCB = 40k, VON2 = VPRESDET = 0V, TA = +25C, unless otherwise noted.) TURN-ON WAVEFORM ON-RESISTANCE vs. TEMPERATURE 0V 30 0V 25 0V 20 0A 10 35 TEMPERATURE (C) 60 0V VOUT 10V/div ILOAD = 5A ON1 RISING/FALLING THRESHOLD VOLTAGE vs. TEMPERATURE MAX5976 toc08 VOUT 10V/div ILOAD 2A/div VPG 10V/div VFAULT 10V/div 0V ILOAD 5A/div ILOAD = 5A 0A FAULT SHUTDOWN WAVEFORM--SHORT CIRCUIT 0V 0V ILOAD 5A/div 4ms/div VOUT 10V/div 0A VPG 10V/div 0V 4ms/div MAX5976 toc07 0V VOUT 10V/div 0V VPG 10V/div 85 FAULT SHUTDOWN WAVEFORM--OVERLOAD (SLOW TRIP) VON1 2V/div ILOAD 10A/div 0A VPG 10V/div 0V VFAULT 10V/div 0V 1.24 1.22 1.20 VON1 RISING 1.18 1.16 1.14 VON1 FALLING 1.12 1.10 -40 4ms/div 2ms/div MAX5976 toc09 35 -15 MAX5976 toc06 VON1 2V/div VON1 RISING/FALLING THRESHOLD VOLTAGE VIN = 12V ILOAD = 100mA -40 NORMAL TURN-OFF WAVEFORM MAX5976 toc05 MAX5976 toc04 40 -15 10 35 60 85 TEMPERATURE (C) CIRCUIT-BREAKER THRESHOLD TIME vs. OVERCURRENT AUTORETRY FUNCTIONALITY MAX5976 toc10 MAX5976 toc11 VON1 1V/div ILOAD = 7A VOUT 500mV/div 0V 0V VOUT 5V/div ILOAD 2A/div 0V VPG 5V/div 0V VFAULT 10V/div 0V 0V 4ms/div 40ms/div 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 MAX5976 toc12 PG ASSERTION DELAY CIRCUIT-BREAKER THRESHOLD TIME (ms) ON-RESISTANCE (mI) MAX5976A/MAX5976B 2.7V to 18V, 7A, Hot-Swap Solution VIN = 12V RCB = 19.9kI 0 500 1000 1500 2000 OVERCURRENT (%) 4 2500 3000 2.7V to 18V, 7A, Hot-Swap Solution PRESDET OUT OUT OUT TOP VIEW 12 11 10 9 ON2 13 CB 14 MA5976A MA5976B REG 15 EP* 1 2 3 4 IN IN IN + GND ON1 16 8 OUT 7 PG 6 FAULT 5 IN TQFN *CONNECT EP TO GND. Pin Description PIN NAME 1 GND FUNCTION 2-5 IN 6 FAULT Fault Status Output. FAULT is an open-drain, active-low output. FAULT asserts low when an overcurrent or overtemperature condition triggers a shutdown. 7 PG Power-Good Output. PG is an open-drain, active-high output. PG pulls low until the internal power MOSFET is fully enhanced. 8-11 OUT 12 PRESDET 13 ON2 Active-Low Enable Logic Input. Pulling ON2 to GND enables the output if PRESDET is low and ON1 is high. 14 CB Current-Limit Threshold Set. Connect a resistor from CB to GND to set the circuit-breaker threshold. 15 REG Internal Regulator Output. Bypass to ground with a 1FF capacitor. Do not power external circuitry using the REG output. 16 ON1 Active-High Enable Comparator Input. Pulling ON1 high enables the output if PRESDET and ON2 are held low. ON1 also sets the undervoltage threshold. See the Setting the Undervoltage Threshold section. -- EP Ground Supply Voltage Input. IN is connected to the drain of the internal 24mI MOSFET. Bypass IN with 1FF capacitor to ground. Add a transient voltage suppressor diode from IN to GND for output short-circuit protection. Load Connection Point. Source of the internal power MOSFET. Active-Low Present-Detect Logic Input. Pulling PRESDET to GND enables the output if ON2 is low and ON1 is high. Exposed Pad. EP is internally grounded. Connect externally to ground plane for effective heat dissipation. Do not use as the only ground connection. 5 MAX5976A/MAX5976B Pin Configuration 2.7V to 18V, 7A, Hot-Swap Solution MAX5976A/MAX5976B Functional Diagram IN OUT 2500X FAULT CHARGE PUMP TEMP SENSE 6A 2X VREG S SET Q 1mA UVLO CB_COMP CONTROL LOGIC R CLR 15A Q 1V SNS_OK ON1 1.25V REFERENCE GENERATOR LDO 1.21V 10A PG ON2 PRESDET O.9 X VIN MAX5976A MAX5976B REG 6 CB GND 2.7V to 18V, 7A, Hot-Swap Solution Enable Logic and Undervoltage Lockout Threshold The MAX5976A/MAX5976B enable the output as shown in Table 1. The ICs turn on the output only when VON1 is high (VON1 > 1.21V) while ON2 and PRESDET are low. The devices turn off the output when VON1 falls below 1.21V - VHYS or whenever ON2 or PRESDET are above VIH. A resistive divider from IN to ON1 and ground provides the flexibility to set the undervoltage lockout threshold to any desired level between VUVLO and 18V. See Figure 1 and Setting the Undervoltage Threshold in the Applications Information section. Startup Once the MAX5976A/MAX5976B output is enabled, the device provides controlled application of power to a load. The voltage at OUT will begin to rise at approximately 18kV/s until the programmed circuit-breaker current level is reached, at which time the MAX5976A/MAX5976B will actively limit inrush current at the circuit-breaker setting. Table 1. Output Enable Truth Table PRECISION ANALOG INPUT ON1 ON2 PRESDET VON1 > VON1_TH 0 0 ON VON1 < (VON1_TH - VON_HYS) X X OFF X 1 X OFF X X 1 OFF LOGIC INPUTS X = Don't care. VON1_TH = 1.21V (typ). VIN R1 MAX5976A MAX5976B ON1 R2 1.21V PRESDET ON2 Figure 1. Undervoltage Threshold Setting OUT Because of this, the inrush current can be easily programmed by appropriate selection of RCB. This startup mode of operation will continue for up to 16ms; after the startup time elapses, the output will either have risen to the IN potential, or if the device is still in current limit, it will shut down and assert the FAULT output low. The resulting dVOUT/dt during startup can be determined according to the following equation: dVOUT/dt (ICB - ILOAD)/COUT In this equation, ILOAD is any current drawn by a load device during the output ramp time that does not charge COUT. Make certain that RCB is chosen such that: VIN x COUT/(ICB - ILOAD) < 16ms This ensures that the output capacitance can be fully charged before the 16ms startup timer elapses. An open-drain power-good output goes high-impedance 16ms (typ) after the output has risen to more than 90% of the input voltage to indicate a successful startup. Charge Pump An integrated charge pump provides the gate-drive voltage for the internal power MOSFET. The charge pump generates +5V potential above VIN to fully enhance the internal power MOSFET. Circuit-Breaker Comparator The current through the internal power MOSFET is compared to a circuit-breaker threshold. An external resistor between CB and ground sets this threshold. The circuit-breaker comparator is designed so that the load current can exceed the threshold for some amount of time before tripping. The time delay varies inversely with the overdrive above the threshold. The greater the overcurrent condition, the faster the response time allowing the devices to tolerate load transients and noise near the circuit-breaker threshold. The ICs also feature catastrophic short-circuit protection. During normal operation, if OUT is shorted directly to ground, a fast protection circuit forces the gate of the internal MOSFET to discharge quickly and disconnect the output from the input. Autoretry/Latch-Off ACTIVEHIGH ENABLE During a fault condition, the devices turn off the internal MOSFET disconnecting the output from the input. The MAX5976A enters an autoretry mode with a fixed 250ms lockout time before reconnect can occur. The MAX5676B latches off and remains off until the enable logic is cycled off and on. 7 MAX5976A/MAX5976B Detailed Description MAX5976A/MAX5976B 2.7V to 18V, 7A, Hot-Swap Solution Power-Good Delay The devices feature an open-drain, power-good output that asserts after 16ms (typ), indicating that OUT has reached (0.9 x VIN) voltage. devices' internal switch goes into normal operation. Use the following equation to calculate the resistors values for the desired undervoltage threshold: VIN R1 = - 1 x R2 V ON1_TH REG The devices include a linear regulator that outputs 2.6V at REG. REG provides power to the internal circuit blocks of the ICs and must not be loaded externally. REG requires a 1FF capacitor to ground for proper operation. Fault Status Output (FAULT) FAULT is an open-drain output that pulls low when a current limit or an overtemperature fault shutdown occurs. FAULT remains low until the next startup cycle. FAULT is capable of sinking up to 5mA when asserted. Thermal Protection The devices enter a thermal shutdown mode in the event of overheating caused by excessive power dissipation or high ambient temperature. When the junction temperature exceeds TJ = +150NC (typ), the internal thermal protection circuitry turns off the internal power MOSFET. The devices recover from thermal shutdown mode once the junction temperature drops by 20NC (typ). where VIN is the desired turn-on voltage for the output and VON1 is 1.21V. R1 and R2 create a resistive divider from VIN to ON1. During normal operating conditions, VON1 must remain above its 1.21V (typ) threshold. If VON1 falls 100mV (VON1_HYS) below the threshold, the internal MOSFET turns off, disconnecting the load from the input. Setting the Current Limit An external resistor from CB to ground sets the current limit for the devices. Use the following formula to set the current limit: 0.175A ILIMIT (A) = x R CB () 1000 Applications Information Setting the Undervoltage Threshold The devices feature an independent ON/OFF control (ON1) for the internal MOSFET. The devices operate with a 2.7V to 18V input voltage range and has a default 2.5V (typ) undervoltage lockout threshold. The internal MOSFET remains off as long as VIN < 2.5V and/or VON1 < VON1_TH. The undervoltage lockout threshold is programmable using a resistive divider between ON1 and GND (Figure 1). When VIN is greater than 2.7V and VON1 exceeds the 1.21V (typ) threshold, the gate of the internal MOSFET enhances to 5V, with respect to VIN and the 8 Chip Information PROCESS: BiCMOS Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 16 TQFN-EP T1655+3 21-0140 90-0073 2.7V to 18V, 7A, Hot-Swap Solution REVISION NUMBER REVISION DATE 0 9/10 Initial release 1 4/11 Added the Package Thermal Characteristics and Startup sections. DESCRIPTION PAGES CHANGED -- 2, 7 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 (c) 2011 Maxim Integrated Products 9 Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX5976A/MAX5976B Revision History