19-1678; Rev 0; 4/00 Network Interface Card Smart Regulator Features ♦ Uninterrupted +3.3V Output An auxiliary switch resistance of only 0.18Ω minimizes output droop from the +3.3V auxiliary supply. In addition, the MAX1810 guarantees that no reverse current flows from the output to any unbiased or inactive input, and remains stable with as little as 1µF of output bypass capacitance at its output. The MAX1810 is available in a compact 8-pin highpower (0.9W) SO package. ♦ No Reverse Current to Inactive Inputs ♦ Up to 500mA Output Current ♦ High-Power 0.9W SO-8 Package ♦ Thermal and Overcurrent Protection ♦ Only 1µF Output Capacitor ♦ Internal 0.18Ω +3.3V Auxiliary Switch Ordering Information ________________________Applications PCI Adapter Cards Network Interface Cards PART TEMP. RANGE PIN-PACKAGE MAX1810ESA -40oC to +85oC 8 SO Modem Cards Pin Configuration Typical Operating Circuit TOP VIEW +5V MAIN INPUT MAIN OUT OUT +3.3V, 500mA COUT 1.0µF +5V STBY INPUT STBY MAX1810 STBY 8 GND 7 GND 3 6 GND AUX 4 5 GND MAIN 2 MAX1810 OUT +3.3V AUX INPUT AUX 1 GND SO ________________________________________________________________ Maxim Integrated Products 1 For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX1810 General Description The MAX1810 powers peripheral component interconnect (PCI) Ethernet network interface cards (NICs), modem cards, and other devices that utilize both the main and auxiliary (standby) voltages supplied by PCIcompliant systems. The device generates an uninterrupted +3.3V at up to 500mA from either a +5V main or a +5V standby supply. When both +5V inputs fall below +4.1V, an internal switch connects the +3.3V auxiliary input to the output. MAX1810 Network Interface Card Smart Regulator ABSOLUTE MAXIMUM RATINGS MAIN, STBY, AUX, OUT to GND ...........................-0.3V to +6.0V OUT to AUX ...........................................................-0.3V to +6.0V OUT Maximum Output Current .......................................1750mA Continuous Power Dissipation (TA = +70°C) 8-Pin SO (derate 11.75mW/°C above +70°C)..............900mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°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 CHARACTERISTICS (VMAIN = VSTBY = +5.0V, VAUX = +3.3V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MAX UNITS 4.5 5.5 V AUX Input Range 3.0 3.6 Maximum Load Current 500 MAIN or STBY Input Range MIN TYP V mA MAIN or STBY Quiescent Current IOUT = 10mA 0.75 3 mA AUX Quiescent Current VMAIN = VSTBY = 0, VAUX = +3.6V 0.2 0.5 mA Reverse Leakage from AUX to MAIN or STBY VAUX = +3.6V, VMAIN or VSTBY = 0 1 20 µA Reverse Leakage from MAIN or STBY to AUX VAUX = 0, VMAIN or VSTBY = +5.5V 1 100 µA OUT Load Capacitance COUT ESR < 50mΩ MAIN or STBY Detect Threshold MAIN or STBY falling MAIN or STBY High Threshold MAIN or STBY rising 4.100 150 +4.5V < (VMAIN or VSTBY) < +5.5V, 0 < IOUT < 400mA 3.234 3.3 OUT Line Regulation +4.5V< (VMAIN or VSTBY) < +5.5V 0.01 OUT Load Regulation IOUT = 30mA to 400mA, VMAIN or VSTBY = +5V 0.22 AUX to OUT Voltage Drop IOUT = 400mA AUX Switch Resistance MAIN = STBY = GND AUX Disable Threshold 2 3.366 520 V % % 118 mV 0.180 0.295 Ω 2.8 900 _______________________________________________________________________________________ V °C °C 20 VAUX = VOUT = 0 V mV 170 Thermal Shutdown Hysteresis V 72 2.5 Thermal Shutdown Current-Limit Threshold 4.275 4.475 MAIN or STBY Hysteresis OUT Voltage µF 1 3.925 1750 mA Network Interface Card Smart Regulator (VMAIN = VSTBY = +5.0V, VAUX = +3.3V, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER CONDITIONS MIN MAX UNITS 4.5 5.5 V AUX Input Range 3.0 3.6 Maximum Load Current 500 MAIN or STBY Input Range MAIN or STBY Quiescent Current IOUT = 10mA AUX Quiescent Current V mA 3 mA VMAIN = VSTBY = 0, VAUX = +3.6V 0.5 mA Reverse Leakage from AUX to MAIN or STBY VAUX = +3.6V, VMAIN or VSTBY = 0 20 µA Reverse Leakage from MAIN or STBY to AUX VAUX = 0, VMAIN or VSTBY = +5.5V 100 µA MAIN or STBY Detect Threshold MAIN or STBY falling 3.925 4.275 V 4.475 3.366 V 3.234 MAIN or STBY High Threshold MAIN or STBY rising OUT Voltage +4.5V < (VMAIN or VSTBY) < +5.5V, 0 < IOUT < 400mA AUX to OUT Voltage Drop IOUT = 400mA AUX Switch Resistance MAIN = STBY = GND AUX Disable Threshold Current-Limit Threshold 2.5 520 VAUX = VOUT = 0 V 118 mV 0.295 Ω 2.8 1750 V mA Note 1: Specifications to -40°C are guaranteed by design, not production tested. Typical Operating Characteristics (VMAIN, VSTBY = +5V, VAUX = +3.3V, COUT = 1µF, TA = +25°C unless otherwise noted.) 1.5 1.0 AUX SWITCH ON 2.5 AUX SWITCH OFF AUX BODY DIODE ACTIVE 2.0 1.5 1.0 0.5 VMAIN AND VSTBY = 0 IOUT = 100mA 0.5 0 1 2 3 INPUT VOLTAGE (V) 4 5 3.25 3.20 3.15 3.10 3.05 0 0 3.30 OUTPUT VOLTAGE (V) 2.0 3.0 MAX1810-03 3.5 OUTPUT VOLTAGE (V) 2.5 3.35 MAX1810-02 IOUT = 250mA 3.0 OUTPUT VOLTAGE (V) 4.0 MAX1810-01 3.5 OUTPUT VOLTAGE vs. OUTPUT CURRENT (MAIN OR STANDBY) OUTPUT VOLTAGE vs. AUX INPUT VOLTAGE MAIN OR STANDBY UNDERVOLTAGE LOCKOUT 3.00 0 0.5 1.0 1.5 2.0 2.5 AUX INPUT VOLTAGE (V) 3.0 3.5 0 100 200 300 400 500 600 OUTPUT CURRENT (mA) _______________________________________________________________________________________ 3 MAX1810 ELECTRICAL CHARACTERISTICS Typical Operating Characteristics (continued) (VMAIN, VSTBY = +5V, VAUX = +3.3V, COUT = 1µF, TA = +25°C unless otherwise noted.) GROUND CURRENT vs. INPUT VOLTAGE (MAIN OR STANDBY) 900 800 3.5 3.3 3.1 2.9 200 IOUT = 250mA 700 GROUND CURRENT (µA) GROUND CURRENT (µA) 3.7 250 MAX1810-05 MAX1810-04 3.9 600 500 400 300 IOUT = 0 200 2.7 AUX SWITCH ON 150 100 50 VMAIN AND VSTBY = 0 IOUT = 0 100 0 2.5 0 100 200 300 400 500 0 0 600 1 2 3 4 5 0 0.5 1.0 1.5 2.0 2.5 3.0 INPUT VOLTAGE (V) AUX INPUT VOLTAGE (V) GROUND CURRENT vs. OUTPUT CURRENT (MAIN OR STANDBY) GROUND CURRENT vs. OUTPUT CURRENT (AUX) AUX ON-RESISTANCE vs. INPUT VOLTAGE VIN = 5V 240 IOUT = 400 mA 220 GROUND CURRENT (µA) 230 1000 800 VIN = 4.2V 600 VMAIN AND VSTBY = 0 400 ON-RESISTANCE (mΩ) 1200 250 MAX1810-07 1400 3.5 MAX1810-09 OUTPUT CURRENT (mA) MAX1810-08 OUTPUT VOLTAGE (V) 1000 GROUND CURRENT vs. INPUT VOLTAGE (AUX) MAX1810-06 OUTPUT VOLTAGE vs. OUTPUT CURRENT (AUX) GROUND CURRENT (µA) 210 190 200 180 160 140 170 200 120 0 150 0 100 200 300 400 500 600 100 0 OUTPUT CURRENT (mA) 100 200 300 400 500 600 OUTPUT CURRENT (mA) 2.6 2.8 3.0 MAX1810-10 240 IOUT = 400mA 220 200 180 160 140 120 100 -40 -25 -10 5 20 35 50 65 80 TEMPERATURE (°C) 4 3.2 AUX INPUT VOLTAGE (V) AUX ON-RESISTANCE vs. TEMPERATURE ON-RESISTANCE (mΩ) MAX1810 Network Interface Card Smart Regulator _______________________________________________________________________________________ 3.4 3.6 Network Interface Card Smart Regulator MAIN OR STANDBY LINE-TRANSIENT RESPONSE MAIN OR STANDBY LOAD-TRANSIENT RESPONSE MAX1810-11 MAX1810-12 5V VIN 4.3V 200mA IOUT 10mA 20mV/div AC-COUPLED VOUT 10mV/div AC-COUPLED VOUT IOUT = 50mA 40µs/div 200µs/div MAIN-T0-STANDBY TRANSITION WAVEFORM MAIN OR STANDBY TO AUX TRANSITION WAVEFORM MAX1810-13 VMAIN MAX1810-14 2V/div VIN MAIN OR STBY 5V 2.4V VOUT 50mV/div AC-COUPLED IOUT = 250mA VSTBY = +5V 3.3V 100mV/div DC-COUPLED VOUT IOUT = 250mA VAUX = +3.3V 20ms/div 10ms/div Pin Description PIN NAME 1 STBY +5V Standby Input FUNCTION 2 MAIN +5V Main Input 3 OUT +3.3V Output. Bypass with a 1µF capacitor to GND. 4 AUX +3.3V Auxilliary Input 5–8 GND Ground. Must connect pins 5 through 8 together to ground plane for power dissipation. _______________________________________________________________________________________ 5 MAX1810 Typical Operating Characteristics (continued) (VMAIN, VSTBY = +5V, VAUX = +3.3V, COUT = 1µF, TA = +25°C unless otherwise noted.) MAX1810 Network Interface Card Smart Regulator Detailed Description 3.3V OUT MAIN 5V DET MAIN REG STBY 5V DET STBY REG AUX 3.3V DET CONTROL LOGIC GND Figure 1. Functional Diagram MAIN OR STBY INPUT VOLTAGE 5.5V Linear Regulators MAIN OR STBY LDO GUARANTEED ON 4.475V 4.1V(TYP) DETECTION THRESHOLD RANGE 3.925V AUX SWITCH GUARANTEED ON (IF AUX > 2.5V) 0 Figure 2. MAIN, STBY, and AUX Transition Voltages 6 The MAX1810 powers NICs, modem cards, or other devices that utilize both the main and auxiliary power supplies in a PCI-compliant system, or other systems that utilize a standby or sleep-mode power bus. The MAX1810 supplies a 3.3V, 500mA output from one of three inputs: a +5V main, a +5V standby, and a +3.3V auxiliary voltage. Each input is separately monitored (Figure 1). During normal operation, the MAIN input powers the fixed +3.3V output (OUT) through an internal linear regulator. When MAIN falls below +4.1V or is disconnected, STBY input powers the output through an internal linear regulator. When the STBY voltage is below +4.1V, an internal switch connects the +3.3V AUX input to OUT. The AUX input maintains the output until AUX falls below +2.5V. Figure 2 shows MAX1810 input transition thresholds. Switchover from one input to another is fast enough to prevent OUT from falling below +3V under all cases unless all inputs are below their required voltages. If both MAIN and STBY are above +4.475V, the MAIN input supplies the output. The MAX1810 prevents reverse current from flowing from the output to any unbiased or low-voltage input. The MAIN or STBY inputs generate the +3.3V output through linear regulators. Each regulator uses an internal P-channel MOSFET pass transistor. The MAIN or STBY linear regulator will operate until its input falls below +4.1V, when it shuts off. Either remaining regulator or AUX input then powers the output. MAIN takes precedence when both MAIN and STBY are valid. +3.3V AUX Switch A 0.18Ω internal switch connects the AUX input to the output when both MAIN and STBY are below 4.1V and AUX is greater than 2.5V. When both MAIN and STBY are below 4.1V or unconnected, and AUX is below 2.5V, the internal switch does not activate and OUT follows AUX less one diode drop. Thermal and Overcurrent Protection Thermal overload protection limits total power dissipation in the MAX1810. When the junction temperature exceeds T J = +170°C, the MAX1810 turns off. The device turns back on once its junction temperature drops by approximately +20°C. A continuous short at OUT will result in a pulsed output as the thermal overload circuitry cycles the device on and off. _______________________________________________________________________________________ Network Interface Card Smart Regulator MAX1810 MAXIMUM CONTINUOUS CURRENT LIMIT 1.2 1.0 0.8 0.6 0.4 0.2 TA = +70°C TA = +50°C TA = +80°C TJ(MAX) = +150°C +5V MAIN INPUT MAIN 2.2µF TYPICAL SUPPLY VOLTAGE LIMIT 1.4 UNDERVOLTAGE LOCKOUT LIMIT MAXIMUM OUTPUT CURRENT (A) 1.6 +5V STBY INPUT COUT 1.0µF STBY 2.2µF +3.3V AUX INPUT OUT * MAX1810 * AUX 0.1µF OUT +3.3V, 500mA GND * 0 3.5 4.0 4.5 5.0 5.5 6.0 *REQUIRED ONLY IF INPUT SUPPLIES DO NOT HAVE NEARBY OUTPUT CAPACITANCE. SUPPLY VOLTAGE (V) Figure 3. Power Operating Region: Maximum Output Current vs. Supply Voltage Thermal overload protection safeguards the MAX1810 in the event of fault conditions. For continuous operation, do not exceed the absolute maximum junctiontemperature rating of TJ = +150°C. Both the MAIN and STBY regulators also feature overcurrent protection nominally at 900mA. The AUX switch is not current limited. Operating Region and Power Dissipation Maximum power dissipation of the MAX1810 depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of airflow. The power dissipation of the device is P = IOUT (VIN – VOUT). The resulting maximum power dissipation is: PMAX = ((TJ(MAX) – TA) / (θJC + θCA)) where TJ(MAX) is the maximum junction temperature (150°C) and TA is the ambient temperature, θJC is the thermal resistance from the die junction to the package case, and θCA is the thermal resistance from the case through the PC board, copper traces, and other materials to the surrounding air (Figure 3). For optimum power dissipation, use a large ground plane with good thermal contact to pins 5 through 8. For multilayer boards, multiple vias are recommended. Figure 4. Typical Application Circuit Applications Information Capacitor Selection The MAX1810 requires a 1µF ceramic bypass capacitor at OUT to maintain regulator stability (Figure 4). When switching between input supplies, the MAX1810 may cause a voltage disturbance on either the MAIN or STBY input. Limit this disturbance to below the hysteresis level (150mV) to guarantee precise switchover. If the MAIN and STBY input supplies do not have filter capacitance of their own near the MAX1810 inputs, then bypass capacitors (2.2µF is recommended) may be needed at MAIN and STBY. If the input supplies to MAIN and STBY already have greater than 2.2µF of output capacitance, then no additional capacitance is required. Place input and output filter capacitors as close to the device as possible to minimize the effect of lead inductance of the PC board traces. Chip Information TRANSISTOR COUNT: 811 PROCESS: BiCMOS _______________________________________________________________________________________ 7 Network Interface Card Smart Regulator SOICN.EPS MAX1810 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 © 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.