19-6083; Rev 0; 12/11 MAX34565 12V Hot-Plug Switch in TDFN Package General Description The MAX34565 is a hot-plug controller for 12V power rails. It is a completely integrated solution including the required power-pass MOSFET device for 12V supplies. During hot-plug, the device controls the supply output voltage ramp (dV/dt) and limits the current at a usercontrolled level. The device also limits the output voltage to protect downstream devices from overvoltage events. The MAX34565 is offered in a latchoff version. Applications SCompletely Integrated Hot-Plug Functionality for 12V Power Rails SOn-Board Power MOSFET SNo High Power RSENSE Resistor Needed SAdjustable Current Limit SAdjustable Output Voltage Slew Rate SThermal Fault Indication SOutput Overvoltage Limiting SOn-Board Thermal Protection PCI/PCI Express® InfiniBandTM/SM Base Stations RAID/Hard Drives Servers Switches/Routers Features SOn-Board Charge Pump SLatchoff Version Ordering Information appears at end of data sheet. +12V SUPPLY Functional Diagram VCC UVLO 5V REG 68mΩ CHARGE PUMP LOAD +12V LOAD ILIM RILIM CURRENT LIMIT OVERVOLTAGE LIMIT MAX34565 GND VRAMP CVRAMP VOHT 17µA EN/FAULT 1.4V POR BLANKING THERMAL LIMIT VOLT THERMAL RESET PCI Express is a registered service mark of PCI-SIG Corp. InfiniBand is a trademark and service mark of InfiniBand Trade Association. For related parts and recommended products to use with this part, refer to: www.maxim-ic.com/MAX34565.related ����������������������������������������������������������������� 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. MAX34565 12V Hot-Plug Switch in TDFN Package ABSOLUTE MAXIMUM RATINGS (All voltages relative to GND.) Voltage Range on VCC Continuous..........................................................-0.3V to +18V 1ms.....................................................................-0.3V to +22V Voltage Range on ILIM, VRAMP............... -0.3V to (VCC + 0.3V), not to exceed +18V Voltage on EN/FAULT..............................................-0.3V to +6V 12V Drain Current (TA = +25NC, 0.5sq in. pad)... 3.6A (continuous) Continuous Power Dissipation (TA = +70NC) TDFN (derate at 24.4mW/NC above +70NC)............1951.2mW Operating Junction Temperature...................... -40NC to +150NC Storage Temperature Range ........................... -55NC to +150NC Lead Temperature (soldering, 10s).................................+300NC Soldering Temperature (reflow).......................................+260NC 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. RECOMMENDED OPERATING CONDITIONS (TJ = -40NC to +150NC, unless otherwise noted.) PARAMETER SYMBOL VCC Voltage VCC RILIM Value RILIM EN/FAULT Low Level (LOAD Disabled) VOLT EN/FAULT High Level (LOAD Enabled) VOHT CONDITIONS (Notes 1, 2) MIN TYP MAX UNITS 9 12 13.2 V 30 I 0.80 V 12 3.3 V ELECTRICAL CHARACTERISTICS (VCC = 12V, TJ = +25NC, unless otherwise noted.) PARAMETER SYMBOL Supply Current ICC UVLO Rising VUR UVLO Falling VUF UVLO Hysteresis VUH CONDITIONS MIN TYP MAX UNITS 1.6 2.25 mA 7.5 8.0 8.5 V 6.5 7.0 7.5 V (Note 3) 1 On-Resistance RON 68 MOSFET Output Capacitance COUT 400 Shutdown Junction Temperature TSHDN Thermal Hysteresis THYS Overvoltage Clamp VOVC Power-On Short-Circuit Current Limit (Kelvin Sense) ISCL Operating Overload Current Limit (Kelvin Sense) IOVL VRAMP Time (0V to 12V) tVRAMP (Note 4) +140 +155 V 88 pF +175 40 RILIM = 15.4I (Note 4) mI NC NC 13.5 15 16.5 V 2.75 3.44 4.25 A RILIM = 24.9I 2.1 A RILIM = 15.4I 4.6 A RILIM = 24.9I 3.5 A CVRAMP = 270pF 7 ms CVRAMP = 470pF 12 ms CVRAMP = 1000pF 25 ms ����������������������������������������������������������������� Maxim Integrated Products 2 MAX34565 12V Hot-Plug Switch in TDFN Package ELECTRICAL CHARACTERISTICS (continued) (VCC = 12V, TJ = +25NC, unless otherwise noted.) PARAMETER SYMBOL EN/FAULT Fault Output Voltage CONDITIONS MIN VFAULT TYP 0.82 MAX UNITS 1.95 V Note 1: All voltages are referenced to ground. Currents entering the device are specified positive, and currents exiting the device are negative. Note 2: This supply range guarantees that the LOAD voltage is not clamped by the overvoltage limit. Note 3: Supply current specified with no load on the LOAD pin. Note 4: Guaranteed by design; not production tested. Typical Operating Characteristics (VCC = 12V, TJ = +25°C, unless otherwise noted.) CURRENT LIMIT vs. TEMPERATURE CURRENT LIMIT (A) IOVL 4.0 3.5 ISCL 1.5 1.0 0.5 0 4 ISCL 3 2 18 21 24 27 20 40 60 80 100 120 70 60 15.6 15.4 15.2 40 80 100 120 TEMPERATURE (°C) 80 100 120 SUPPLY CURRENT vs. TEMPERATURE 2.0 1.8 1.6 1.2 1.0 0.8 0.2 0 60 60 0.4 10 14.8 40 0.6 20 10Ω LOAD 20 1.4 50 30 40 0 TEMPERATURE (°C) ICC (mA) RON (mΩ) 15.8 20 -40 -20 MAX34565 toc05 80 MAX34565 toc04 NO LOAD 0 ISCL 1.5 ON-RESISTANCE vs. TEMPERATURE OVERVOLTAGE CLAMP vs. TEMPERATURE -40 -20 2.0 TEMPERATURE (°C) 16.2 15.0 2.5 0 0 RILIM (Ω) 16.0 3.0 0.5 -40 -20 30 IOVL 1.0 0 15 RILIM = 24Ω 3.5 1 12 OVERVOLTAGE CLAMP (V) 4.0 MAX34565 toc03 IOVL MAX34565 toc06 3.0 2.5 2.0 RILIM = 15Ω 5 CURRENT LIMIT vs. TEMPERATURE 4.5 CURRENT LIMIT (A) MAX34565 toc01 5.5 5.0 4.5 CURRENT LIMIT (A) 6 MAX34565 toc02 CURRENT LIMIT vs. RILIM 6.0 0 -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) -40 -20 0 20 40 60 80 100 120 TEMPERATURE (°C) ����������������������������������������������������������������� Maxim Integrated Products 3 MAX34565 12V Hot-Plug Switch in TDFN Package Typical Operating Characteristics (continued) (VCC = 12V, TJ = +25°C, unless otherwise noted.) TURN-ON WAVEFORMS (VCC = 12V, EN/FAULT) TURN-ON WAVEFORMS (VCC = 12V, 10Ω RESISTIVE LOAD) MAX34565 toc07 MAX34565 toc08 RILIM = 15Ω 2V/div VCC VCC 2V/div LOAD LOAD 500mA/div EN/FAULT LOAD CURRENT 5ms/div 5ms/div TURN-ON WAVEFORMS (VCC = 12V, 3300µF CAPACITIVE LOAD) MAX34565 toc09 RILIM = 15Ω 2V/div VCC LOAD LOAD CURRENT 1A/div 5ms/div ����������������������������������������������������������������� Maxim Integrated Products 4 MAX34565 12V Hot-Plug Switch in TDFN Package Pin Configuration TOP VIEW LOAD LOAD LOAD LOAD LOAD 10 9 8 7 6 MAX34565 VCC/EP + 1 2 3 4 GND VRAMP EN/ ILIM FAULT 5 N.C. TDFN (3mm x 3mm) Pin Description PIN NAME 1 GND FUNCTION 2 VRAMP Voltage Ramp Control. A capacitor connected to this pin determines the voltage ramp of the LOAD output during turn-on according to the equation tVRAMP = 25E6 x CVRAMP for voltage ramp from 0 to 12V. This pin can be left open circuit for a minimum ramp time. 3 EN/FAULT Enable/Fault. This pin is a multiple function digital input-output pin. When this pin is externally pulled low, the MOSFET is turned off. When this pin is left open or not externally driven, the internal pullup reference pulls the input high, and the MOSFET is allowed to turn on. Note: Do not use an external pullup on this pin. If the device experiences a thermal fault, this pin becomes an output that is pulled internally to a mid-level voltage, VFAULT. 4 ILIM Supply Current Limit Adjust. A resistor from this pin to LOAD determines the current limit for the pass connection. 5 N.C. No Connection. Do not connect any signal to this pin. Ground Connection 6 7 8 LOAD Load Output. N-channel power MOSFET source connection. 9 10 — VCC/EP 12V Supply Input/Exposed Pad. Power-supply input and n-channel power MOSFET drain connection. Should be connected to a large trace or plane. The EP also acts as a heatsink, and can dissipate heat from the device. ����������������������������������������������������������������� Maxim Integrated Products 5 MAX34565 12V Hot-Plug Switch in TDFN Package The MAX34565 is a self-contained hot-plug switch intended to be used on +12V power buses to limit through current and to control the power-up outputvoltage ramp. The device begins to operate when VCC exceeds the undervoltage lockout level, VUR. At this level, the enable circuit and EN/FAULT pin become active. Once the device has been enabled by exceeding VOLT on the EN/FAULT pin, a gate voltage is applied to the power MOSFET, allowing current to begin flowing from the VCC pad to LOAD. The device contains an on-board 68mI n-channel power MOSFET that is actively closed-loop controlled to ensure that an adjustable current limit is not exceeded. The maximum allowable current through the device is determined by an external resistor connected to the ILIM pin. The device also contains the ability to control the powerup output-voltage ramp. A capacitor connected to the VRAMP pin sets the desired voltage ramp rate. The output voltage is unconditionally clamped to keep input overvoltage stresses from harming the load. The device has an on-board temperature sensor with hysteresis. If operating conditions cause the device to exceed an internal thermal limit, the device unconditionally shuts down and latches off while waiting for a power-on reset. In the event of thermal shutdown, the device drives the EN/FAULT pin to an intermediate voltage, VFAULT. Undervoltage Lockout When voltage is applied to VCC, the undervoltage lockout rising limit, VUR, must be exceeded before the MOSFET circuit is enabled. When the voltage on VCC drops below VUF, the current through the MOSFET is blocked. Note that to allow current to pass through to the LOAD pins, VCC must exceed VUR and the voltage on EN/FAULT must exceed VOHT. the device’s output is disabled. If the internal temperature of the device exceeds TSHDN, a thermal fault occurs and the device drives EN/FAULT to VFAULT. See Figure 1 for the EN/FAULT signal levels. An open-drain device should be connected to the EN/ FAULT pin for proper operation. Because the device pulls EN/FAULT to VFAULT (a three-state condition) in the event of thermal shutdown, this pin should not be connected to an external pullup device. See Figure 2 for a typical application circuit. LOAD ENABLED EN/FAULT SIGNAL Detailed Description THERMAL SHUTDOWN/ FAULT VOHT VFAULT LOAD DISABLED VOLT Figure 1. EN/FAULT Signal Levels 12V VCC LOAD MAX34565 RILIM EN/FAULT ILIM Enable/Fault Function (EN/FAULT) The EN/FAULT pin can be used to control the output of the device and to indicate that a thermal fault has occurred. The voltage level of the EN/FAULT pin is compared to two internal sources: voltage on limit (VOHT) and voltage off limit (VOLT). When VCC is above VUR and the voltage level on EN/FAULT exceeds VOHT, the voltage ramp circuit turns on, enabling the device’s output. When the voltage on EN/FAULT is below VOLT, GND VRAMP ENABLE Figure 2. Typical Application Circuit ����������������������������������������������������������������� Maxim Integrated Products 6 MAX34565 12V Hot-Plug Switch in TDFN Package Output-Voltage Ramp (VRAMP) Direct and Kelvin Current Sensing The voltage ramp circuit uses an operational amplifier to control the gate bias of the n-channel power MOSFET. When the voltage on EN/FAULT is below VOLT, a FET is used to keep CVRAMP discharged, which forces the output voltage to GND. Once the voltage on EN/FAULT is above VOHT, an internal current source begins to charge the external capacitor, CVRAMP, connected to the VRAMP pin. The amplifier controls the gate of the power MOSFET so that the LOAD output voltage divided by two tracks the rising voltage level of CVRAMP. The output voltage continues to ramp until it reaches either the input VCC level or the overvoltage clamp limits. The current limit circuit can be biased in one of two ways: direct sensing or Kelvin sensing. Using direct sensing, the sense resistor is connected between the ILIM pin and the LOAD pins (Figure 3). Because the bond wires of all five LOAD pins are in parallel, the on-resistance is slightly lower. Using Kelvin sensing, only one of the LOAD pins is connected to the ILIM pin through the sense resistor (Figure 4). Using this circuit, the voltage on the die is sensed, negating any impact of the bond wire resistance. Because four LOAD pins are connected in parallel, the on-resistance is slightly higher. Overvoltage Limit The device enters a thermal shutdown state when the temperature of the power MOSFET reaches or exceeds TSHDN, approximately +155NC. When TSHDN is exceeded, the thermal-limiting circuitry disables the device using the enable circuitry. The EN/FAULT pin is driven to VFAULT. The device is offered in two different versions: an autoretry version and a latchoff version. The overvoltage-limiting clamp monitors the VRAMP voltage level compared to an internal voltage reference. When the voltage on VRAMP exceeds VOVC/2, the gate voltage of the n-channel power MOSFET is reduced, limiting the voltage on LOAD to VOVC even as VCC increases. If the device is in overvoltage for an extended period of time, the device may overheat and enter thermal shutdown. This is caused by the power created by the voltage drop across the power MOSFET and the load current. Current Limit The load current is continuously monitored during the initial voltage ramping (ISCL) and during normal operation (IOVL). If the current exceeds the current limit that is set by the external resistance at ILIM, the gate voltage of the power MOSFET is decreased, reducing the output current to the set current limit. Current is limited by the device comparing the voltage difference between the LOAD and ILIM pins to an internal reference voltage. When the output power is initially ramping up, the current limit is ISCL. Once the voltage ramping is complete, the current limit is IOVL. The lower ISCL current limit protects the source if there is a dead short on initial power-up. If the high current is maintained, the device will heat up and the internal temperature will eventually reach TSHDN. The device act as a fuse and automatically disable the current flowing to the load when the temperature of the power MOSFET has exceeded the shutdown junction temperature, TSHDN. Thermal Shutdown ILOAD LOAD LOAD TO APPLICATION LOAD MAX34565 LOAD LOAD RLIM ILIM Figure 3. Direct Sensing Circuit ILOAD LOAD LOAD TO APPLICATION LOAD MAX34565 LOAD LOAD RLIM ILIM Figure 4. Kelvin Sensing Circuit ����������������������������������������������������������������� Maxim Integrated Products 7 MAX34565 12V Hot-Plug Switch in TDFN Package Latchoff Version Once the latchoff version has entered thermal shutdown, it does not attempt to turn back on. The only way to turn this device back on is to cycle the power to the device. When power is reapplied ton the VCC pad, the junction temperature needs to be less than TSHDN for the device to be enabled. Applications Information RILIM. To greatly reduce this offset, it is recommended that one of the LOAD pins have a dedicated connection to ILIM though RILIM, and not be used to pass the LOAD current, ILOAD (Figure 6). This would leave four LOAD pins to pass ILOAD, which should be sufficient. Because there is only a small amount of current passed from this lone LOAD pin to ILIM, there is a negligible voltage offset applied to the internal comparator. This method is the best way to attain an accurate current limit for ILOAD. Exposed Pad (VCC) The exposed pad is the voltage supply pin for the device and should be connected to a large trace or plane. The exposed pad also acts as a heatsink, and can dissipate heat from the device. Decoupling Capacitors It is of utmost importance to properly bypass the device’s supply pins. A decoupling capacitor absorbs the energy stored in the supply and board parasitic inductance when the FET is turned off, thereby reducing the magnitude of overshoot of VCC. This can be accomplished by using a high-quality (low ESR, low ESL) ceramic capacitor soldered directly between the VCC and GND connections. Any series resistance with this bypass capacitor lowers its effectiveness and is not recommended. A minimum 0.5FF ceramic capacitor is required (Figure 4). However, depending on the parasitic inductances present in the end application, a larger capacitor could be necessary. Current Limiting Resistor A small resistor (2I to 10I) in series with the GND pin of the device limits current flow during momentary reverse avalanche break down, and consequently limits total parasitic charge injected into the device (Figure 5). If this method is used, it is imperative that the bypass capacitor be directly across chip VCC and ground connections, though not through this resistor. LOAD and ILIM Connections Small parasitic resistances in the bond wires of the LOAD pins and in the traces connected to the LOAD pins can result in a voltage offset while current is flowing. Since the voltage drop across RILIM is used to set the ISCL and IOVL limits, this induced offset can increase the value of ISCL and IOVL from the specified values for any given VCC 0.5µF MINIMUM REQUIRED MAX34565 GND 2Ω TO 10Ω RECOMMENDED BOARD GROUND Figure 5. Power Conditioning Circuit LOAD TO APPLICATION LOAD LOAD MAX34565 LOAD LOAD RLIM ILIM Figure 6. LOAD and ILIM Connections ����������������������������������������������������������������� Maxim Integrated Products 8 MAX34565 12V Hot-Plug Switch in TDFN Package Ordering Information PART TEMP RANGE THERMAL SHUTDOWN PIN-PACKAGE MAX34565ETB+ -40NC to +150NC Latchoff 10 TDFN-EP* MAX34565ETB+T -40NC to +150NC Latchoff 10 TDFN-EP* +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed pad. Package Information For the latest package outline information and land patterns (footprints), 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. 10 TDFN-EP T1033+2 21-0137 90-0061 ����������������������������������������������������������������� Maxim Integrated Products 9 MAX34565 12V Hot-Plug Switch in TDFN Package Revision History REVISION NUMBER REVISION DATE 0 12/11 DESCRIPTION Initial release PAGES CHANGED — 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. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2011 Maxim Integrated Products 10 Maxim is a registered trademark of Maxim Integrated Products, Inc.