19-1832; Rev 0a; 1/01 -48V Simple Swapper Hot-Swap Switches Features ♦ Provides Safe Hot Swap for -16V to -65V Power Supplies ♦ 280mA Current Limit for MAX5911 ♦ 415mA Current Limit for MAX5912 ♦ Zero-Current Load Disconnect ♦ Integrated Power FET ♦ Status Output Reports Fault Condition ♦ Internal Switch-Protection Circuitry ♦ Built-In Thermal Shutdown ♦ DGND Can Vary Up to ±5V with Respect to AGND Ordering Information PART TEMP. RANGE -40°C to +85°C 8 SO MAX5912ESE -40°C to +85°C 16 SO Simple Swapper is a trademark of Maxim Integrated Products, Inc. Pin Configurations TOP VIEW GATE 1 VIN 2 Applications IP Phones Network Routers Network Switches Internet Appliances Power-Over-LAN Typical Operating Circuit VIN (-48V) VOUT VIN +3.3V 0.1µF 3.3kΩ MAX5911 MAX5912 UVLO PIN-PACKAGE MAX5911ESA FAULT 3 MAX5911 DGND 4 8 UVLO 7 VOUT 6 AGND 5 ENABLE 8 SO N.C.* 1 16 N.C.* N.C.* 2 15 UVLO GATE 3 14 VOUT VIN 4 13 V IN MAX5912 12 VIN VIN 5 FAULT 6 11 AGND DGND 7 10 ENABLE N.C.* 8 9 LOAD FAULT POSITIVE LOGIC ENABLE DGND AGND N.C.* 16 SO AGND DGND *THESE PINS ARE NOT INTERNALLY CONNECTED. ________________________________________________________________ Maxim Integrated Products 1 For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX5911/MAX5912 General Description The MAX5911/MAX5912 are fully integrated hot-swap switches for negative supply rails. These devices allow the safe insertion and removal of circuit cards into live backplanes or ports without causing problematic glitches on the negative power-supply rail. They also monitor various circuit parameters and disconnect the load if a fault condition occurs, alerting the host with a logic-level FAULT output. The MAX5911/MAX5912 operate over a voltage range of -16V to -65V and are designed to permit hot plugging of an IP phone into a hub, but are not limited to that operation. During startup, an internal power FET regulates the current between the backplane power source and the load to 280mA for MAX5911 and 415mA for MAX5912. After startup, the FET is fully enhanced to reduce its on-resistance. To ensure robust operation, the MAX5911/ MAX5912 contain built-in safety features that prevent damage to the internal FET. They include an enable input, which responds to positive logic signals (+3.3V or +5V), allowing the host system to disconnect the load. ENABLE is also used to reset the device after a latching fault condition occurs. The MAX5911/MAX5912 Simple Swapper™ hot-swap ICs monitor four parameters for these fault conditions: undervoltage lockout (UVLO), power-not-good, zerocurrent detection, and thermal shutdown. These devices are available in the extended temperature range, -40°C to +85°C. The MAX5911 and MAX5912 come in 8-pin and 16-pin SOIC packages, respectively. MAX5911/MAX5912 -48V Simple Swapper Hot-Swap Switches ABSOLUTE MAXIMUM RATINGS Voltages are with respect to AGND, unless otherwise noted. VIN ..........................................................................+0.3V to -70V VOUT ............................................................+0.3V to (VIN - 0.3V) ENABLE to DGND ..................................................-0.3V to +11V ENABLE to VIN .......................................................-0.3V to +70V FAULT to DGND .....................................................-0.3V to +11V UVLO to VIN ............................................................-0.3V to +11V DGND ..........................................................................-5V to +5V DGND to VIN ...........................................................-0.3V to +70V FAULT Sink Current ............................................................10mA Continuous Output Current ...............................Internally Limited Continuous Power Dissipation (TA = +70°C) 8-Pin SO (derate 5.9mW/°C above +70°C)..................470mW 16-Pin SO (derate 12.9mW/°C above +70°C)...........1039mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-60°C to +150°C Lead Temperature (soldering, 10s) .................................+300°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 SPECIFICATIONS (VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, and TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL Input Voltage Range VIN Supply Current IIN Maximum VOUT Current DMOS On-Resistance IOUT(MAX) RDS(ON) VOUT Leakage Current 2 CONDITIONS MIN TYP MAX UNITS -16 V 1.5 2.5 mA -65 Measured at AGND at the end of output voltage slew MAX5911 -310 -280 -250 MAX5912 -457 -415 -373 2.5 4 Ω Measured on VOUT when internal DMOS is shut off 10 µA 0.8 V 300 µA VOUT = VIN + 5V MAX5911 IOUT = -225mA, MAX5912 IOUT = -350mA ENABLE Low Voltage VIL Referenced to DGND ENABLE High Voltage VIH Referenced to DGND ENABLE High Input Current IIH VENABLE = +3.3V 2.0 mA V 140 ENABLE Low Pulse Width (Note 1) tEPW FAULT Output Low Voltage VOL I FAULT = 3mA 0.4 V FAULT Output Leakage Current IOH V FAULT = +3.3V 10 µA Zero-Current Detection Threshold IFTH Decreasing load current -4 mA Zero-Current Detection Threshold Hysteresis IFHY Zero-Current Detection Delay (Note 2) IFDEL Current-Limit Delay (Note 3) tLIMIT Power-Good Threshold VPG Power-Good Hysteresis PGHYS 200 -12 ns -8 1.5 280 350 1.95 VOUT shorted to AGND |VIN - VOUT|, |VIN - VOUT| decreasing % of VPG mA 520 ms 10 20 µs 2.15 2.35 5 _______________________________________________________________________________________ V % -48V Simple Swapper Hot-Swap Switches (VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, and TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL Power-Not-Good Output Delay (Note 4) After |VIN - VOUT| increases above (VPG + PGHYS) PGDEL Thermal Shutdown Temperature (Note 5) CONDITIONS MAX UNITS 8 14 20 ms o 140 UVLO open circuit, |VIN| increasing UVLO Hysteresis UVLO open circuit, percentage of UVLO threshold UVLO Comparator Threshold Referenced to VIN, UVLO open circuit, |VIN| increasing Note 1: Note 2: Note 3: Note 4: Note 5: TYP TJ Default UVLO UVLO Input Resistance MIN -30 -28 RUVLO -26 C V 12 % +1.258 V 95 kΩ Minimum ENABLE low pulse width required to unlatch fault condition. The delay from IOUT falling below the zero-current threshold until FAULT is latched low and VOUT is disabled. The time from an output overcurrent or short-circuit condition until the output goes into current limit. The time from VOUT falling until FAULT is asserted low. FAULT is not latched for Power-Not-Good condition. When the device goes into thermal shutdown, the output is disabled and FAULT is latched low. Typical Operating Characteristics (VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, RLOAD = 1.8kΩ, TA = +25°C, unless otherwise noted.) NO LOAD 1.4 1.2 1.0 1.530 1.525 1.520 1.515 -65 -55 -45 -35 SUPPLY VOLTAGE (V) -25 -15 2.6 2.4 2.2 2.0 1.8 1.6 1.510 0.8 ILOAD = 150mA 2.8 ON-RESISTANCE (Ω) 1.535 SUPPLY CURRENT (mA) 1.6 3.0 MAX5911 toc02 NO LOAD SUPPLY CURRENT (mA) 1.540 MAX5911 toc01 1.8 ON-RESISTANCE vs. AMBIENT TEMPERATURE SUPPLY CURRENT vs. AMBIENT TEMPERATURE MAX5911 toc03 SUPPLY CURRENT vs. SUPPLY VOLTAGE -40 -15 10 35 TEMPERATURE (°C) 60 85 -40 -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX5911/MAX5912 ELECTRICAL SPECIFICATIONS (continued) Typical Operating Characteristics (continued) (VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, RLOAD = 1.8kΩ, TA = +25°C, unless otherwise noted.) MAX5911 TURN-ON WAVEFORMS (RL = 1.8kΩ, CL = 47µF) MAX5911 TURN-OFF WAVEFORMS (RL = 1.8kΩ, CL = NONE) MAX5911 toc05 MAX5911 toc04 A A 0 A 0 0 0 0 0 B B C B C C 0 0 0 t = 10µs/div t = 2ms/div A: ENABLE, 5V/div B: VOUT, 20V/div C: FAULT, 2V/div C: FAULT, 2V/div A: ENABLE, 5V/div B: VOUT, 20V/div MAX5911 OVERCURRENT RESPONSE MAX5911 TURN-OFF WAVEFORMS (RL = 1.8kΩ, CL = 47µF) MAX5911 ZERO-CURRENT RESPONSE MAX5911 toc07 A A 0 0 0 0 B A 0 0 B B 0 0 C C t = 10µs/div C: FAULT, 2V/div MAX5911 toc09 A: ENABLE, 5V/div B: VOUT, 20V/div MAX5911 toc06 MAX5911 TURN-ON WAVEFORMS (RL = 1.8kΩ, CL = NONE) MAX5911 toc08 MAX5911/MAX5912 -48V Simple Swapper Hot-Swap Switches C 0 t = 50ms/div t = 100ms/div A: ENABLE, 5V/div B: VOUT, 20V/div C: FAULT, 2V/div A: FAULT, 5V/div B: VOUT, 50V/div MAX5912 TURN-ON WAVEFORMS (RL = 1.8kΩ, CL = NONE) 0 0 0 0 0 B B C C 0 0 0 t = 10µs/div A: ENABLE, 5V/div B: VOUT, 20V/div 4 MAX5911 toc12 A 0 C t = 10µs/div t = 1ms/div C: FAULT, 2V/div t = 50ms/div C: IOUT, 50mA/div MAX5912 TURN-OFF WAVEFORMS (RL = 1.8kΩ, CL = NONE) MAX5911 toc11 A B A: FAULT, 5V/div B: VOUT, 50V/div MAX5912 TURN-ON WAVEFORMS (RL = 1.8kΩ, CL = 47µF) MAX5911 toc10 A C: IOUT, 200mA/div A: ENABLE, 5V/div B: VOUT, 20V/div C: FAULT, 2V/div A: ENABLE, 5V/div B: VOUT, 20V/div _______________________________________________________________________________________ C: FAULT, 2V/div -48V Simple Swapper Hot-Swap Switches MAX5912 TURN-OFF WAVEFORMS (RL = 1.8kΩ, CL = 47µF) MAX5911 toc13 A MAX5911 toc15 MAX5911 toc14 A A 0 0 0 0 B MAX5912 ZERO-CURRENT RESPONSE MAX5912 OVERCURRENT RESPONSE 0 0 B B 0 0 C C C 0 t = 100ms/div A: ENABLE, 5V/div B: VOUT, 20V/div t = 40ms/div t = 40ms/div C: FAULT, 2V/div A: FAULT, 5V/div B: VOUT, 20V/div C: IOUT, 200mA/div A: FAULT, 5V/div B: VOUT, 20V/div C: IOUT, 100mA/div Pin Description PIN NAME FUNCTION 3 GATE Gate of the Internal Power MOSFET. Normally leave open circuit. To slow down the output voltage ramp, connect two capacitors, one to VIN and one to VOUT. See GATE Connections for details. 2 4, 5, 12, 13 VIN 3 6 FAULT Fault Logic Output, open-drain. Tie FAULT to the positive logic supply with a 3.3kΩ resistor. Referenced to DGND. 4 7 DGND Digital Ground. Ground reference level for the external positive logic, FAULT, and ENABLE. DGND can vary up to ±5V with respect to AGND to accommodate differential ground voltages in large systems. ENABLE Input. Turns on and off the internal FET. ENABLE is a positive logiclevel input referenced to DGND. Drive ENABLE high to enable VOUT. Drive ENABLE low to disable VOUT. Pulse ENABLE low to reset the MAX5911/ MAX5912 after a latched fault condition occurs. MAX5911 MAX5912 1 Voltage Input Terminal. Bypass VIN, to AGND with a 0.1µF capacitor to improve noise immunity. 5 10 ENABLE 6 11 AGND Analog Ground. Ground reference level for VIN, VOUT, and UVLO. 7 14 VOUT Voltage Output Terminal Undervoltage Lockout Input. Leave UVLO open circuit for default setting of -28V. Alternatively, UVLO can be connected to a resistive divider to set the lockout voltage (see the Changing the Undervoltage Lockout Setting section). The comparator threshold level is +1.258V with respect to VIN. 8 15 UVLO — 1, 2, 8, 9, 16 N.C. No Connection. No internal connection. _______________________________________________________________________________________ 5 MAX5911/MAX5912 Typical Operating Characteristics (continued) (VIN = -48V, AGND = DGND = 0, UVLO = open circuit, VENABLE = +3.3V, RLOAD = 1.8kΩ, TA = +25°C, unless otherwise noted.) MAX5911/MAX5912 -48V Simple Swapper Hot-Swap Switches MAX5911/MAX5912 FAULT LEVEL SHIFTER ENABLE Normal Operation CONTROL LOGIC AGND include an enable input that responds to positive logic, allowing the host system to turn the FET switch on or off. The enable input is also used to reset the devices after an error condition has latched the output FET off. DGND 2.11MΩ GATE UVLO 99.5kΩ +1.258VREF VIN VOUT |VIN| VPG (min) = 1.8V VPG |VIN - VOUT|, VPG (typ) = 2V POWER-GOOD HYSTERESIS (5% OF VPG) VPG (max) = 2.2V |VOUT| Startup When power is first applied with ENABLE high, or when ENABLE is asserted, the MAX5911/MAX5912 limit the current to the load to 280mA/415mA. If the output voltage has not reached the power-good threshold within the 14ms power-good delay, FAULT is pulled low. FAULT stays low until the output voltage exceeds the power-good threshold, at which time it is released and becomes high impedance. Undervoltage Lockout Fault If VIN ≤ UVLO, where UVLO is the desired voltage at which the UVLO fault occurs, FAULT is pulled low and the internal FET is turned off. If the condition persists for over 350ms (IFDEL), the FET is latched off. The default UVLO voltage is -28V, but it can be adjusted using an external resistive divider (see the Changing the Undervoltage Lockout Setting section). Once the FET is latched off, ENABLE must be pulsed low then brought back high to release FAULT and enable VOUT. 0 Thermal Shutdown Fault POWER-NOT-GOOD DELAY POWER GOOD Figure 1. Functional Block Diagram Detailed Description Figure 1 shows a functional block diagram. The MAX5911/MAX5912 are hot-swap switches for negative supply rails. The devices allow the safe insertion and removal of circuit cards into live backplanes or ports without causing undue glitches on the negative powersupply rail. They operate over the -16V to -65V voltage range. The devices act as a current regulator, using their on-board FET to limit the amount of current drawn from the backplane to 280mA for MAX5911 and 415mA for MAX5912. If the load current exceeds that current limit, the internal switch behaves like a constant current source. The MAX5911/MAX5912 monitor the input voltage, the output voltage, the output current, and the die temperature. They assert their FAULT output if they detect an error condition. A zero-current load disconnect feature activates if the load current drops below 8mA for over 350ms. They also 6 The MAX5911/MAX5912 monitor their internal die temperatures. If the temperature of the die exceeds +140°C, FAULT is pulled low and the internal FET is latched off. ENABLE must be pulsed low and then brought high again to reset the FET latch, and release FAULT, provided the die is below the thermal shutdown temperature by 5°C (typ). Power-Not-Good Fault If |VIN - VOUT| is more than the power-good threshold for over 14ms, FAULT is pulled low. When the output voltage exceeds the power-good threshold, FAULT is released. FAULT output is not latched during a powernot-good fault. Zero-Current Detection If the load current drops below 8mA for over 350ms, FAULT is pulled low and the FET is latched off. ENABLE must be pulsed low and then brought high again to release FAULT and enable VOUT. Applications Information Chosing A Device The MAX5911 will output up to 280mA (typ) and the MAX5912 up to 415mA (typ). In applications where high heat is expected, use the MAX5912 for its superior _______________________________________________________________________________________ -48V Simple Swapper Hot-Swap Switches VIN (-16V TO -65V) VOUT VIN 0.1µF R1 +3.3V UVLO R2 3.3kΩ MAX5911 MAX5912 LOAD FAULT POSITIVE LOGIC Changing the Undervoltage Lockout Setting The UVLO value defaults to -28V if the UVLO pin is left open circuit. The lockout voltage can be changed with a resistive divider. Connect the divider from V IN to AGND, and connect the center node of the divider to the UVLO pin. Figure 2 shows an example circuit. Use R1 ≤ 10kΩ, then calculate R2 using: ENABLE DGND AGND CHOOSE R1 10kΩ, THEN CALCULATE R2 USING: R2 = R1 VIN (UVLO) 1.258 -1 Figure 2. UVLO Voltage Set by an External Resistive Divider VIN(UVLO) R2 = R1 x - 1 1.258 where VIN(UVLO) is the desired lockout voltage. heat dissipation properties, and always solder all of its VIN pins to a large section of circuit board copper. Logic Control The enable input responds to +3.3V logic signals and will force the internal FET off if it is pulled low. This feature allows the host to disconnect the load from the power bus if required. Additionally, all fault conditions that latch the internal FET off must be cleared by pulsing ENABLE low for at least 200ns, then reasserting ENABLE before normal operation can resume. Chip Information TRANSISTOR COUNT: 1021 PROCESS: BiCMOS GATE Connections GATE connects to the gate of the internal N-channel power MOSFET. Normally this pin should be left open circuit. To slow down the voltage ramp at VOUT, connect capacitors from GATE to VOUT and VIN. Size the capacitors so that the GATE to VIN capacitor is ten times the size of the GATE to V OUT capacitor. This technique to slow down the output voltage ramp will also cause the output discharge time to increase if the capacitor values exceed about 1nF. Additionally, this technique will cause the time delay for a power-notgood fault to increase. _______________________________________________________________________________________ 7 MAX5911/MAX5912 FAULT Output The FAULT output is open-drain and is pulled low if the MAX5911/MAX5912 detect an undervoltage fault, a thermal fault, a power-not-good fault, or a zero-current fault. See the Normal Operation section for specific details of fault operation. Connect FAULT to the logic supply with a pullup resistor; 3.3kΩ is sufficient in most cases. -48V Simple Swapper Hot-Swap Switches SOICN.EPS MAX5911/MAX5912 Package Information 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. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.