MAX5943 19-3378 Rev 2 10/07 FireWire Current Limiter and Low-Drop ORing Switch Controller General Description Features Provides Safe Hot Swap for 7.5V to 37V Power The MAX5943 is a fully integrated power-management Supplies IC for FireWire applications. This device controls two external power n-channel MOSFETs to regulate current UL-Recognized FireWire/IEEE 1394 Protective from the input power supply to the load and performs Circuit low-voltage-drop, power-supply ORing. The MAX5943 Low-Drop Power ORing with Ultra-Fast Turn-Off operates over a 7.5V to 37V input range and provides Programmable Active Current Limit (MAX5943A) inrush and output current limit in addition to a diode ORing function suitable for FireWire applications. The Programmable Circuit Breaker (MAX5943BMAX5943E) MAX5943 FireWire/IEEE 1394 protective circuit (Figure 12) is UL recognized. 5% Current-Limit Sensing Accuracy The MAX5943 allows the safe insertion and removal of Programmable Current-Limit/Circuit-Breaker FireWire peripherals into a live FireWire port by providing Timeout inrush current control and an output current-limiting func- Fast Current-Limit Response to Output Short- tion. The ORing feature provides a very efficient way to Circuit Conditions (MAX5943A) protect the FireWire port when connected to another Drives External N-Channel Power MOSFETs FireWire peripheral that sources a higher voltage. By turn- Overcurrent Fault Status Output ing off both external MOSFETS, the MAX5943 provides a true bidirectional load disconnect. A low-current shut- Latched or Autoretry Overcurrent Fault down mode disables the MAX5943, resulting in less than Management 10A supply current. A pin-selectable input allows 10A Shutdown Current latched or autoretry fault management after a fault. ON/OFF Control Allows Undervoltage Lockout The MAX5943A features a current-limit function that Programming actively limits the current drawn by the load with a pro- Fast Load Disconnect Control Through ON Input grammable timeout. The MAX5943BMAX5943E do not actively limit the load current but provide a circuit-breaker Ordering Information function. See the Selector Guide for the default and pro- grammable circuit-breaker timeouts. PART TEMP RANGE PIN-PACKAGE The MAX5943 operates over the -40C to +85C extended MAX5943AEEE -40C to +85C 16 QSOP temperature range and is available in a 16-pin QSOP MAX5943BEEE -40C to +85C 16 QSOP package. MAX5943CEEE -40C to +85C 16 QSOP Applications MAX5943DEEE -40C to +85C 16 QSOP FireWire Desktop/Notebook Port MAX5943EEEE -40C to +85C 16 QSOP FireWire Peripheral Device Current Limit Pin Configuration FireWire Hub Hot Swap TOP VIEW ON 1 16 IN FAULT 2 15 SENSE TIM 3 14 GATE1 ILIM 4 MAX5943 13 N.C. LATCH 5 12 GATE2 Typical Operating Circuit and Selector Guide appear at end OR ADJ 6 11 OUT of data sheet. N.C. 7 10 N.C. FireWire is a registered trademark of Apple Computers, Inc. ONQ1 8 9 GND IEEE 1394 is a trademark of the Institute of Electrical and Electronics Engineers trademark. QSOP UL is a registered trademark of Underwriters Laboratories, Inc. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.FireWire Current Limiter and Low-Drop ORing Switch Controller ABSOLUTE MAXIMUM RATINGS (Voltages referenced to GND, unless otherwise noted.) Continuous Power Dissipation (T = +70C) A IN............................................................................-0.3V to +80V 16-Pin QSOP (derate 8.3mW/C above +70C)...........667mW OUT ........................................................................-0.3V to +80V Operating Temperature Range ...........................-40C to +85C SENSE to IN..............................................................-1V to +0.3V Maximum Junction Temperature .....................................+150C GATE1 to SENSE......................................................-0.3V to +8V Storage Temperature Range .............................-60C to +150C GATE2 to OUT (internally clamped).........................-0.3V to +8V ESD Rating (Human Body Model)......................................2000V FAULT.....................................................................-0.3V to +85V Lead Temperature (soldering, 10s) .................................+300C ON, TIM, ILIM, LATCH, OR ADJ, ONQ1 ..........-0.3V to (IN + 0.3V) 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 = 7.5V to 37V, GND = 0V, and T = -40C to +85C, unless otherwise noted. Typical values are at V = 12V, T = +25C.) IN A IN A (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SUPPLIES Supply Voltage Range V 7.5 37 V IN Supply Current I V = 3V, no load 1.3 2.3 mA IN ON Shutdown Current I V = 0.4V 5 10 A SD ON IN Default Undervoltage Lockout V V rising, ON = IN 6.2 6.5 6.8 V UVLO IN IN Default Undervoltage Lockout 0.35 V Hysteresis ON Undervoltage Lockout V V rising 1.20 1.24 1.275 V ON REF ON Threshold ON Undervoltage Lockout 70 mV Threshold Hysteresis ON Input Bias Current I 1A ON GATE2 (current-limit/circuit-breaker control) GATE2 Pullup Current I (Note 2) 36 45 54 A G2U 7.5V V 8V 4.25 5.5 6.5 IN GATE2 High Voltage V V - V V G2 GATE2 OUT 8V V 37V 4.5 5.5 6.5 IN ILIM = GND 47.5 50 52.5 Current-Limit/Circuit-Breaker V V - V mV TH IN SENSE ILIM = floating 37 39 41 Threshold Voltage ILIM = IN 55 58.5 61 ILIM = GND 70 75 80 Fast Pulldown Current-Limit V V - V (Note 3) ILIM = floating 54 59 64 mV THF IN SENSE Threshold Voltage (MAX5943A) ILIM = IN 83 88 93 GATE2 Pulldown Current V < (V - V < V , TH IN SENSE) THF I 335 435 535 A G2D (MAX5943A) t < t ILIM GATE2 Fast Pulldown Current (V - V > V , V = V + IN SENSE) THF GATE2 OUT I 80 125 200 mA G2DF (MAX5943A) 4.5V GATE2 Peak Pulldown Current I (V - V = 1V 1.0 A G2DP IN SENSE) (MAX5943A) 2 MAX5943