MAX8555/MAX8555A 13-3087 Rev 0 1/04 Low-Cost, High-Reliability, 0.5V to 3.3V ORing MOSFET Controllers General Description Features Critical loads often employ parallel-connected power Simple, Integrated, and Inexpensive MOSFET supplies with redundancy to enhance system reliability. Controllers The MAX8555/MAX8555A are highly integrated, inex- ORing FET Drive for 0.5V to 3.3V pensive MOSFET controllers that provide isolation and redundant power capability in high-reliability systems. Eliminate ORing Diode Power Dissipation The MAX8555/MAX8555A are used in 0.5V to 3.3V sys- Provide N+1 Redundant Supply Capability for tems, and have an internal charge pump to drive the gates of the N-channel pass elements to (V + 5V). Highly Reliable Systems CS+ During startup, the MAX8555/MAX8555A monitor the Isolate Failed Short-Circuit Supply from voltage drop across the external MOSFETs. Once V CS+ Output BUS approaches or exceeds the bus voltage (V ), the CS- Respond to Reverse Short-Circuit Current MOSFETs are turned on. The MAX8555/MAX8555A fea- in 200ns ture a dual-purpose TIMER input. A single external resistor from TIMER to ground sets the turn-on speed of Adjustable Blank Time the external MOSFETs. Optionally, the TIMER input can Programmable Soft-Start be used as a logic enable input. Once the external MOSFET is turned on, these controllers monitor the Logic Enable Input load, protecting the bus against overvoltage, undervolt- Adjustable Overvoltage and Undervoltage age, and reverse-current fault conditions. The MAX8555 is available with a 40mV reverse-current Trip Points threshold, while the MAX8555A is available with a 20mV Fault-Indicator Output reverse-current threshold. Space-Saving Packages Overvoltage and undervoltage fault thresholds are adjustable and can be disabled. The current-limit trip Ordering Information points are set by the external MOSFETs R , DS(ON) reducing component count. An open-drain, logic-low TEMP PIN- TOP fault output indicates if an overvoltage, undervoltage, or PART RANGE PACKAGE MARK reverse-current fault occurs. The MAX8555 and the MAX8555A can shut down in response to a reverse- 10 TDFN MAX8555ETB -40C to 85C ACC current fault condition as quickly as 200ns. 3mm x 3mm* Both devices come in space-saving 10-pin MAX or MAX8555EUB -40C to 85C 10 MAX 8555EUB TDFN packages and are specified over the extended 10 TDFN -40C to +85C temperature range. MAX8555AETB -40C to 85C ADD 3mm x 3mm* MAX8555AEUB -40C to 85C 10 MAX 8555AEUB Applications *Exposed paddle Point-of-Load Supplies Pin Configurations Power-Supply Modules Servers TOP VIEW Telecom Power Supplies Rectifiers GATE 1 10 CS+ GATE 1 10 CS+ Redundant Power Supplies in High-Availability GND 2 9 CS- GND 2 9 CS- MAX8555/ MAX8555/ Systems MAX8555A VL 3 8 OVP VL 3 8 OVP MAX8555A V 4 7 FAULT V 4 7 FAULT DD DD UVP 5 6 TIMER UVP 5 6 TIMER Typical Operating Circuit appears at end of data sheet. MAX TDFN Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLELow-Cost, High-Reliability, 0.5V to 3.3V ORing MOSFET Controllers ABSOLUTE MAXIMUM RATINGS GATE to GND .........................................................-0.3V to +12V Operating Temperature Range ...........................-40C to +85C FAULT, VL to GND ...................................................-0.3V to +6V Junction Temperature......................................................+150C OVP, UVP, TIMER, CS+, CS- to GND .......-0.3V to +(V + 0.3V) Storage Temperature Range .............................-65C to +150C VL V to GND..................................................(V - 0.3V) to +18V Lead Temperature (soldering, 10s) .................................+300C DD VL Continuous Power Dissipation (T = +70C) A 10-Pin MAX (derate 5.6mW/C above +70C) ...........444mW 10-Pin TDFN (derate 24.4mW/C above +70C) .......1951mW 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 (V = 12V, V = 1.4V, V = 1.5V, R = 25k, V = 1V, V = 0.25V, R = 50k, C = C = C = 0.01F, DD CS- CS+ TIMER UVP OVP FAULT VDD GATE VL T = 0C to +85C, unless otherwise noted.) A PARAMETER CONDITIONS MIN TYP MAX UNITS V SUPPLY DD VL unconnected 8.00 13.25 V Input Voltage V = 2.5V V DD TIMER VL = V 3.0 5.5 DD VL unconnected, V = 2.5V, V = 13.25V 2.0 3.3 TIMER DD V Supply Current mA DD V = V = 5V, V = 2.5V 0.04 0.2 DD VL TIMER V Shutdown Current V = 0V, V = 13.25V 3.0 mA DD TIMER DD Rising threshold 14.0 14.4 15.0 V Overvoltage Internal DD V Threshold Falling threshold 13.3 13.8 14.5 VL SUPPLY VL Input Voltage V = V 3.0 5.5 V DD VL VL Supply Current V = V = 5V, V = 2.5V 1.8 3.0 mA DD VL TIMER VL Current in Shutdown Mode TIMER = GND, V = V = 5V 1.6 3.0 mA DD VL VL Output Voltage V = 8V to 13.25V, I = 0A 3.80 4.1 4.45 V DD VL VL = V , rising threshold 2.78 2.82 2.90 DD VL Undervoltage Lockout V VL = V , falling threshold 2.68 2.75 2.82 DD CS INPUTS CS+, CS- Input Current V = 2.5V, V = 3.0V 5.2 A TIMER CS Offset Input Current (CS+, CS-) V = 3.0V, Figure 4 -250 +250 nA CS CS+/CS- Input Range (Note 1) 0.5 V - 0.5 V VL V = +3V, V = 0V, I -0.5 CS+ CS- CS- CS Isolation A V = +3V, V = 0V, I -0.5 CS- CS+ CS+ CHARGE-PUMP VOLTAGE V = 8V to 13.25V DD GATE Voltage, V Measured from GATE to CS+ 5.0 5.25 5.5 V GATE V = V = 5V DD VL R = 20k 187 TIMER R = 125k 450 Charge-Pump Switching TIMER kHz Frequency R = open 500 TIMER V = 1.5V 550 TIMER 2 MAX8555/MAX8555A