KIT ATION EVALU E L B A IL AVA 19-3443; Rev 3; 4/10 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor The MAX5924/MAX5925/MAX5926 1V to 13.2V hot-swap controllers allow the safe insertion and removal of circuit cards into live backplanes. These devices hot swap supplies ranging from 1V to 13.2V provided that the device supply voltage, VCC, is at or above 2.25V and the hotswapped supply, VS, does not exceed VCC. The MAX5924/MAX5925/MAX5926 hot-swap controllers limit the inrush current to the load and provide a circuitbreaker function for overcurrent protection. The devices operate with or without a sense resistor. When operating without a sense resistor, load-probing circuitry ensures a short circuit is not present during startup, then gradually turns on the external MOSFET. After the load probing is complete, on-chip comparators provide overcurrent protection by monitoring the voltage drop across the external MOSFET on-resistance. In the event of a fault condition, the load is disconnected. The MAX5924/MAX5925/MAX5926 include many integrated features that reduce component count and design time, including configurable turn-on voltage, slew rate, and circuit-breaker threshold. An on-board charge pump provides the gate drive for a low-cost, external n-channel MOSFET. The MAX5924/MAX5925/MAX5926 are available with open-drain PGOOD and/or PGOOD outputs. The MAX5925/MAX5926 also feature a circuit breaker with temperature-compensated R DS(ON) sensing. The MAX5926 features a selectable 0ppm/°C or 3300ppm/°C temperature coefficient. The MAX5924 temperature coefficient is 0ppm/°C and the MAX5925 temperature coefficient is 3300ppm/°C. Autoretry and latched faultmanagement configurations are available (see the Selector Guide). Features o o o o o o o o o o Hot Swap 1V to 13.2V with VCC ≥ 2.25V Drive High-Side n-Channel MOSFET Operation With or Without RSENSE Temperature-Compensated RDS(ON) Sensing Protected During Turn-On into Shorted Load Adjustable Circuit-Breaker Threshold Programmable Slew-Rate Control Programmable Turn-On Voltage Autoretry or Latched Fault Management 10-Pin µMAX® or 16-Pin QSOP Packages Ordering Information PART MAX5924AEUB TEMP RANGE PIN-PACKAGE -40°C to +85°C 10 µMAX MAX5924BEUB -40°C to +85°C 10 µMAX MAX5924CEUB* -40°C to +85°C 10 µMAX MAX5924DEUB* -40°C to +85°C 10 µMAX MAX5925AEUB -40°C to +85°C 10 µMAX MAX5925BEUB* -40°C to +85°C 10 µMAX MAX5925CEUB* -40°C to +85°C 10 µMAX MAX5925DEUB* -40°C to +85°C 10 µMAX MAX5926EEE -40°C to +85°C 16 QSOP–EP** *Future product—contact factory for availability. **EP = Exposed pad. Typical Operating Circuits TYPICAL OPERATION WITHOUT RSENSE Applications Base Stations RAID BACKPLANE VS VCC REMOVABLE CARD N 1V TO VCC VOUT 2.25V TO 13.2V RCB Remote-Access Servers Network Routers and Switches RSC CB Servers GATE SENSE OUT SC_DET VCC Portable Device Bays GND GND MAX5925 MAX5926 µMAX is a registered trademark of Maxim Integrated Products, Inc. SEE FIGURE 1 FOR A DETAILED TYPICAL OPERATING CIRCUIT WITHOUT RSENSE. Selector Guide appears at end of data sheet. Pin Configurations appear at end of data sheet. Typical Operating Circuits continued at end of data sheet. ________________________________________________________________ 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. MAX5924/MAX5925/MAX5926 General Description MAX5924/MAX5925/MAX5926 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND, unless otherwise noted.) VCC .........................................................................-0.3V to +14V GATE*.....................................................................-0.3V to +20V All Other Pins ............-0.3V to the lower of (VCC + 0.3V) or +14V SC_DET Current (200ms pulse width, 15% duty cycle) ...140mA Continuous Current (all other pins) .....................................20mA Continuous Power Dissipation (TA = +70°C) 10-Pin µMAX (derate 6.9mW/°C above +70°C) ...........556mW 16-Pin QSOP (derate 18.9mW/°C above +70°C).......1509mW 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 Soldering Temperature (reflow) .......................................+260°C *GATE is internally driven and clamped. Do not drive GATE with external source. 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 (VCC, EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) = 0V; VS (see Figure 1) = +1.05V to VCC; TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = 5V, RL = 500Ω from OUT to GND, CL = 1µF, SLEW = open, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 13.2 V POWER SUPPLIES VCC Operating Range VCC 2.7 VS Operating Range VS VS as defined in Figure 1 Supply Current ICC FET is fully enhanced, SC_DET = VCC 1.0 VCC V 1.5 2.5 mA 2.06 2.47 UNDERVOLTAGE LOCKOUT (UVLO) UVLO Threshold VUVLO VCC UVLO Deglitch Time tDG VCC UVLO Startup Delay tD,UVLO Default value, VS and VCC increasing, Figure 1 1.73 (Note 2) 900 V µs 123 200 350 ms 2.7V < VCC < 5V 4 30 65 5V < VCC < 13.2V 3 10 20 43 102 205 ms 172 200 235 mV LOAD-PROBE Load-Probe Resistance (Note 3) Load-Probe Timeout Load-Probe Threshold Voltage RLP tLP VLP,TH (Note 4) Ω CIRCUIT BREAKER ICB Circuit-Breaker Programming Current ICB25 ICB85 2 VCC = 2.7V and VCB TC = high = 1V (MAX5926), MAX5924 2.7V ≤ VCC ≤ 13.2V TC = low (MAX5926), MAX5925 (Note 5) TC = low (MAX5926), MAX5925 (Note 5) 37 34 37 42 VCC = 2.7V, VCB = 1V, TA = +25°C 30 40 50 2.7V ≤ VCC ≤ 13.2V, TA = +25°C 40 50 60 VCC = 2.7V and VCB = 1V, TA = +85°C 40 50 60 2.7V ≤ VCC ≤ 13.2V, TA = +85°C 50 60 70 µA _______________________________________________________________________________________ 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor (VCC, EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) = 0V; VS (see Figure 1) = +1.05V to VCC; TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = 5V, RL = 500Ω from OUT to GND, CL = 1µF, SLEW = open, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL Circuit-Breaker Programming Current During Startup ICB,SU Circuit-Breaker Enable Threshold VCB,EN Circuit-Breaker Comparator Offset Voltage VCB_OS CONDITIONS MIN TYP MAX 2 x ICB VGATE - VOUT, rising gate voltage (Note 6) 2.3 UNITS µA 3.6 4.65 V 0.3 ±4.7 mV Fast Circuit-Breaker Offset Resistor RCBF Figure 3 1.2 1.9 2.7 kΩ Slow Circuit-Breaker Delay tCBS VCB - VSENSE = 10mV 0.95 1.6 2.95 ms Fast Circuit-Breaker Delay tCBF VCB - VSENSE = 500mV Circuit-Breaker Trip Gate Pulldown Current IGATE,PD Circuit-Breaker Temperature Coefficient OUT Current TCICB VGATE = 2.5V, VCC = 13.2V 13.5 280 ns 27 mA MAX5924, TC = high (MAX5926) 0 MAX5925, TC = low (MAX5926) 3300 IOUT ppm/°C 120 µA 7.2 V MOSFET DRIVER External Gate Drive VGS Load Voltage Slew Rate Gate Pullup Current Capacity SR IGATE VGATE - VOUT 2.7V ≤ VCC ≤ 13.2V SLEW = open, CGATE = 10nF 4.2 5.5 2.19 9.5 CSLEW = 300nF, CGATE = 10nF (Note 8) VGATE = 0V V/ms 0.84 239 µA ENABLE COMPARATOR EN, EN1 Reference Threshold EN, EN1 Hysteresis VEN/UVLO VEN (MAX5924/MAX5925) or VEN1 (MAX5926) rising 0.747 VEN,HYS 0.795 0.850 30 V mV IEN EN (MAX5924/MAX5925) = VCC, EN1 (MAX5926) = VCC ±8 ±50 nA Power-Good Output Low Voltage VOL IOL = 1mA 0.3 0.4 V Power-Good Output Open-Drain Leakage Current IOH PGOOD/PGOOD = 13.2V 0.2 1 µA 3.6 4.7 EN, EN1 Input Bias Current DIGITAL OUTPUTS (PGOOD, PGOOD) Power-Good Trip Point Power-Good Hysteresis VTHPGOOD VGATE - VOUT, rising gate voltage VPG,HYS VCB_EN 0.36 V V _______________________________________________________________________________________ 3 MAX5924/MAX5925/MAX5926 ELECTRICAL CHARACTERISTICS (continued) ELECTRICAL CHARACTERISTICS (continued) (VCC, EN (MAX5924/MAX5925), EN1 (MAX5926) = +2.7V to +13.2V; EN2 (MAX5926) = 0V; VS (see Figure 1) = +1.05V to VCC; TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = 5V, RL = 500Ω from OUT to GND, CL = 1µF, SLEW = open, TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 0.6 1.6 3.3 s LOGIC AND TIMING (TC, LATCH (MAX5926), EN2 (MAX5926) Autoretry Delay tRETRY Autoretry mode VIH Input Voltage 2.0 V 0.4 VIL Input Bias Current IBIAS Logic high at 13.2V Time to Clear a Latched Fault TCLR MAX5924A/MAX5924B MAX5925A/MAX5925B MAX5926 in latched mode 3 µA 200 µS All devices are 100% tested at TA = +25°C and +85°C. All temperature limits at -40°C are guaranteed by design. VCC drops 30% below the undervoltage lockout voltage during tDG are ignored. RLP is the resistance measured between VCC and SC_DET during the load-probing phase, tLP. Tested at +25°C & +85°C. Guaranteed by design at -40°C. The circuit-breaker programming current increases linearly from VCC = 2.25V to 5V. See the Circuit-Breaker Current vs. Supply Voltage graph in the Typical Operating Characteristics. Note 6: See the Startup Mode section for more information. Note 7: VGATE is clamped to 17V (typ) above ground. Note 8: dv/dt = 330 x 10-9/CSLEW (V/ms), nMOS device used for measurement was IRF9530N. Slew rate is measured at the load. Note 1: Note 2: Note 3: Note 4: Note 5: Typical Operating Characteristics (VCC = 5V, CL = 1µF, CSLEW = 330nF, CGATE = 10nF, RL = 500Ω, Figure 1, TA = +25°C, unless otherwise noted.) MAX5926 SUPPLY CURRENT vs. TEMPERATURE ENABLED 2.4 1.6 VCC = VS 2.0 6 VCC = 13.2V DISABLED VCC = 5.0V 1.2 VCC = 3.0V 0.8 0.8 0.4 VGATE - VS (V) 1.2 ICC (mA) 1.6 4 6 8 VCC (V) 10 12 14 VS = 1V VS = 3V 4 VS = VCC VS = 5V 3 0 2 5 VCC = 2.25V 0.4 0 4 7 MAX5924 toc02 VCC = VS MAX5924 toc01 2.0 GATE-DRIVE VOLTAGE vs. SUPPLY VOLTAGE MAX5924 toc03 MAX5926 SUPPLY CURRENT vs. SUPPLY VOLTAGE ICC (mA) MAX5924/MAX5925/MAX5926 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor 2 -40 -15 10 35 TEMPERATURE (°C) 60 85 2 4 6 8 VCC (V) _______________________________________________________________________________________ 10 12 14 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor CIRCUIT-BREAKER CURRENT vs. SUPPLY VOLTAGE (TC = 3300ppm/°C) CIRCUIT-BREAKER CURRENT vs. HOT-SWAP VOLTAGE VCC = VS 5.5 TC = 3300ppm/°C 52 VCC = 5.0V 55 MAX5924 toc05 56 MAX5924 toc04 6.0 MAX5924 toc06 GATE DRIVE VOLTAGE vs. TEMPERATURE VCC = VS 53 VCC = 3.0V 4.5 48 ICB (µA) CB (µ ) VGS (V) 5.0 51 44 VCC = 13.2V 3.0 VCC = 13.2V 36 10 35 TEMPERATURE (°C) 60 85 0 2 6 8 10 12 47 2 14 4 6 CIRCUIT-BREAKER PROGRAMMING CURRENT vs. TEMPERATURE 80 MAX5924 toc07 VCC = VS 39.2 VCC = VS = 5V 70 39.0 ICB (µA) 38.6 10 12 14 SLEW RATE vs. CSLEW 60 38.8 8 VCC (V) VS (V) CIRCUIT-BREAKER CURRENT vs. SUPPLY VOLTAGE (TC = 0ppm/°C) 39.4 4 100 SLEW RATE (V/ms) -15 MAX5924 toc08 -40 ICB (µA) 49 TC = 0ppm/°C 40 3.5 TC = 3300ppm/°C 50 40 MAX5924 toc09 4.0 10 1 TC = 0ppm/°C 38.4 30 38.2 20 2 4 6 8 VCC (V) 10 12 14 0.1 -40 -15 10 35 TEMPERATURE (°C) 60 85 0 500 1000 1500 2000 CSLEW (nF) _______________________________________________________________________________________ 5 MAX5924/MAX5925/MAX5926 Typical Operating Characteristics (continued) (VCC = 5V, CL = 1µF, CSLEW = 330nF, CGATE = 10nF, RL = 500Ω, Figure 1, TA = +25°C, unless otherwise noted.) MAX5924/MAX5925/MAX5926 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor Typical Operating Characteristics (continued) (VCC = 5V, CL = 1µF, CSLEW = 330nF, CGATE = 10nF, RL = 500Ω, Figure 1, TA = +25°C, unless otherwise noted.) TURN-ON WAVEFORM (CSLEW = OPEN) TURN-ON WAVEFORM (CSLEW = 330nF) MAX5924 toc10 GATE 5V/div MAX5924 toc11 GATE 5V/div 0V 0V OUT 5V/div 0V OUT 5V/div 0V PGOOD 5V/div 0V PGOOD 5V/div 0V 200µs/div 2ms/div TURN-OFF WAVEFORM OVERCURRENT CIRCUIT-BREAKER EVENT MAX5924 toc12 MAX5924 toc13 1A/div EN1 5V/div 0V IFET 0A tCBS GATE 10V/div 5V/div GATE 0V 10V/div 0V 0V OUT PGOOD 5V/div 0V 5V/div PGOOD 0V 400µs/div 2µs/div SHORT-CIRCUIT CIRCUIT-BREAKER EVENT AUTORETRY DELAY MAX5924 toc14 IFET MAX5924 toc15 1A/div EN1 5V/div 0V tD,UVLO 0A GATE 5V/div OUT 0V 5V/div 0V tRETRY 5V/div SC_DET 0V OUT 100mV/div 5V/div 0V PGOOD 0V 2µs/div 6 400ms/div _______________________________________________________________________________________ 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor OVERCURRENT FAULT AND AUTORETRY DELAY UVLO DELAY AND LOAD PROBING MAX5924 toc16 EN1 GATE SC_DET MAX5924 toc17 5V/div 0V 5V/div 0V EN1 5V/div SC_DET 5V/div 0V tD,UVLO tLP 5V/div 0V OUT 200mV/div 0V OUT 100mV/div 0V 0V 400ms/div 40ms/div UVLO RESPONSE UVLO DEGLITCH RESPONSE MAX5924 toc18 MAX5924 toc19 >tDG 2V/div GATE GATE 2V/div <tDG 0V 0V 1V/div 1V/div VCC VCC 0V 200µs/div 0V 200µs/div _______________________________________________________________________________________ 7 MAX5924/MAX5925/MAX5926 Typical Operating Characteristics (continued) (VCC = 5V, CL = 1µF, CSLEW = 330nF, CGATE = 10nF, RL = 500Ω, Figure 1, TA = +25°C, unless otherwise noted.) 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor MAX5924/MAX5925/MAX5926 Pin Description PIN MAX5924A/ MAX5924B/ MAX5924C/ MAX5924D/ MAX5926 MAX5925A/ MAX5925B/ MAX5925C MAX5925D 1 8 1 1 NAME VCC FUNCTION Power-Supply Input. Connect VCC to a voltage between 2.47V and 13.2V. VCC must always be equal to or greater than VS (see Figure 1). 2 2 2 SC_DET Short-Circuit Detection Output. Connect SC_DET to VOUT through a series resistor, RSC, when not using RSENSE. SC_DET forces current (limited to ≈200mA) into the external load through RSC at startup to determine whether there is a short circuit (load probing). Connect SC_DET directly to VCC when using RSENSE, Do not connect SC_DET to VCC when not using RSENSE in an attempt to disable load probing. 3 3 — EN ON/OFF Control Input. Drive EN high to enable the device. Drive EN low to disable the device. An optional external resistive-divider connected between VCC, EN, and GND sets the programmable turn-on voltage. 4 — 4 PGOOD Open-Drain Active-Low Power-Good Output — 4 7 PGOOD Open-Drain Active-High Power-Good Output 5 5 5 GND Ground 6 6 12 SLEW Slew-Rate Adjustment Input. Connect an external capacitor between SLEW and GND to adjust the gate slew rate. Leave SLEW unconnected for the default slew rate. 7 7 13 GATE Gate-Drive Output. Connect GATE to the gate of the external n-channel MOSFET. 8 8 14 OUT Output Voltage. Connect OUT to the source of the external MOSFET. 9 9 15 SENSE 10 10 16 CB Circuit-Breaker Threshold Programming Input. Connect an external resistor, RCB, from CB to VS to set the circuit-breaker threshold voltage. Circuit-Breaker Sense Input. Connect SENSE to OUT when not using an external RSENSE (Figure 1). Connect SENSE to the drain of the external MOSFET when using an external RSENSE (Figure 2). — — 3 EN1 Active-High ON/OFF Control Input. Drive EN1 high to enable the device when EN2 is low. Drive EN1 low to disable the device, regardless of the state of EN2. An optional external resistive-divider between VCC, EN1, and GND sets the programmable turn-on voltage while EN2 is low. — — 6 EN2 Active-Low ON/OFF Control Input. Drive EN2 low to enable the device when EN1 is high. Drive EN2 high to disable the device, regardless of the state of EN1. — — 8 LATCH Latch Mode Input. Drive LATCH low for autoretry mode. Drive LATCH high for latched mode. — — 9 TC Circuit-Breaker Temperature Coefficient Selection Input. Drive TC low to select a 3300ppm/°C temperature coefficient. Drive TC high to select a 0ppm/°C temperature coefficient. — — 10, 11 N.C. — — EP EP No Connection. Not internally connected. Exposed Pad. Connect EP to GND. _______________________________________________________________________________________ 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor VS VCC MAX5924/MAX5925/MAX5926 BACKPLANE REMOVABLE CARD 1V TO VCC 2.25V TO 13.2V RSC RCB 20kΩ 10Ω CB GATE SENSE V+ OUT VCC ON (ON*) SC_DET 1µF GND MAX5925 MAX5926 EN (EN1**) EN2** EN EN2 TC** CL PGOOD** PGOOD (PGOOD*) GND SLEW LATCH** GND CSLEW *MAX5925A AND MAX5925C. **MAX5926. DC-DC CONVERTER Figure 1. Typical Operating Circuit (Without RSENSE) BACKPLANE REMOVABLE CARD RSENSE 1V TO VCC VS 2.25V TO 13.2V VCC 20kΩ RCB 10Ω 10Ω CB SENSE GATE VCC GND V+ OUT ON (ON*) SC_DET 1µF EN (EN1**) EN2** EN EN2 VCC TC** MAX5924 MAX5926 CL PGOOD** PGOOD (PGOOD*) LATCH** *MAX5924A AND MAX5924C. **MAX5926. GND GND SLEW CSLEW DC-DC CONVERTER Figure 2. Typical Operating Circuit (With RSENSE) _______________________________________________________________________________________ 9 MAX5924/MAX5925/MAX5926 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor GATE 50kΩ VCC CHARGE PUMP VZ = 9V SLEW N A MAX5924 MAX5925 MAX5926 2µA VCC RLP N VCB,TH CB SC_DET SLOW COMPARATOR VS 75kΩ OUT TIMER RCBF 0.2V VCBF,TH 75kΩ FAST COMPARATOR OSCILLATOR ICB TC*** PGOOD* LOGIC CONTROL SENSE PGOOD** LATCH*** VCC EN/(EN1***) VCC 0.8V VCC GND 1.24V EN2*** *MAX5924B, MAX5924D, MAX5925B, MAX5925D, MAX5926 ONLY. **MAX5924A, MAX5924C, MAX5925A, MAX5925C, MAX5926 ONLY. ***MAX5926 ONLY. Figure 3. Functional Diagram 10 ______________________________________________________________________________________ 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor The MAX5924/MAX5925/MAX5926 are hot-swap controller ICs designed for applications where a line card is inserted into a live backplane. Normally, when a line card is plugged into a live backplane, the card’s discharged filter capacitors provide a low impedance that can momentarily cause the main power supply to collapse. The MAX5924/MAX5925/MAX5926 are designed to reside either in the backplane or in the removable card to provide inrush current limiting and short-circuit protection. This is achieved using an external n-channel MOSFET and an optional external current-sense resistor. Several critical parameters can be configured: • Slew rate (inrush current) MAX5924/MAX5925/MAX5926 Detailed Description VCC RISES ABOVE VUVLO NO ENABLE TRUE? YES FAULT MANAGEMENT UVLO 200ms DELAY YES • Circuit-breaker threshold RSENSE PRESENT? NO ICB,SU = 2 x ICB DISABLE SLOW COMPARATOR • Turn-on voltage • Fault-management mode (MAX5926) • Circuit-breaker temperature coefficient (MAX5926) See the Selector Guide for a device-specific list of factory-preset features and parameters. DISABLE FAULT PROTECTION, ENABLE LOAD PROBE LOAD PROBE SUCCESSFUL? NO YES SLEW-RATE-LIMITED STARTUP Startup Mode It is important that both VCC and VS rise at a minimum rate of 100mV/ms during the critical time when power voltages are below those values required for proper logic control of internal circuitry. This applies for 0.5V ≤ VCC ≤ 2.5V and 0.5V ≤ VS ≤ 0.8V. This is particularly true when LATCH is tied high. The MAX5924/MAX5925/MAX5926 control an external MOSFET placed in the positive power-supply pathway. When power is first applied, the MAX5924/MAX5925/ MAX5926 hold the MOSFET off indefinitely if the supply voltage is below the undervoltage lockout level or if the device is disabled (see the EN (MAX5924/MAX5925), EN1/EN2 (MAX5926) section). If neither of these conditions exist, the device enters a UVLO startup delay period for ≈200ms. Next, the MAX5924/MAX5925/ MAX5926 detect whether an external sense resistor is present; and then autoconfigure accordingly (see Figure 4). • If no sense resistor is present, bilevel fault protection is disabled and load-probing circuitry is enabled (see the Load Probing section). If load probing is not successful, the fault is managed according to the selected fault management mode (see the Latched and Auto-Retry Fault Management section). If load probing (see the Load Probing section) is successful, slew-rate limiting is employed to gradually turn on the MOSFET. NO VGS ≥ VCB,EN VGS ≥ VTHPGOOD YES ENABLE STANDARD BILEVEL FAULT PROTECTION BEGIN NORMAL OPERATION PGOOD Figure 4. Startup Flow Chart • If the device detects an external RSENSE, circuitbreaker threshold is set at 2xICB, the slow comparator is disabled, the startup phase begins without delay for load probing, and slew-rate limiting is employed to gradually turn on the MOSFET. During the startup phase, the voltage at the load, VOUT, rises at a rate determined by the selected slew rate (see the Slew Rate section). The inrush current, IINRUSH, to the load is limited to a level proportional to the load capacitance, CL, and the slew rate: IINRUSH = CL × SR 1000 where SR is the slew rate in V/ms and CL is load capacitance in µF. For operation with and without RSENSE, once VGATE V OUT exceeds V CB,EN , PGOOD and/or PGOOD assert. When VGATE - VOUT = VCB,EN, the MAX5924/ MAX5925/MAX5926 enable standard bilevel fault protection with normal ICB (see the Bilevel Fault Protection section). ______________________________________________________________________________________ 11 Load Probing Normal Operation The MAX5924/MAX5925/MAX5926 load-probing circuitry detects short-circuit conditions during startup. Load probing is active only when no external R SENSE is detected. As the device begins load probing, SC_DET is connected to VCC through an internal switch with an on-resistance of RLP (Figure 6). VCC then charges the load with a probe current limited at ≈200mA. (Figure 1) IPROBE = (VCC - VOUT)/(RLP + RSC) If the load voltage does not reach VLP,TH (0.2V typ) within tLP, a short-circuit fault is detected and the startup mode is terminated according to the selected faultmanagement mode (see the Fault Management section and Figure 5). If no fault condition is present, PGOOD/PGOOD asserts at the end of the startup period (see the Turn-On Waveforms in the Typical Operating Characteristics). Load probing can only be, and must be, employed when not using an external RSENSE. In normal operation, after startup is complete, protection is provided by turning off the external MOSFET when a fault condition is encountered. Dual-speed/ bilevel fault protection incorporates two comparators with different thresholds and response times to monitor the current: 1) Slow comparator. This comparator has a 1.6ms (typ) response time. The slow comparator ignores low-amplitude momentary current glitches. After an extended overcurrent condition, a fault is acknowledged and the MOSFET gate is discharged. 2) Fast comparator. This comparator has a quick response time and a higher threshold voltage. The fast comparator turns off the MOSFET immediately when it detects a large high-current event such as a short circuit. VOUT SR = dV dt SR = dV dt CL = SMALL VLP,TH (0.2V typ) VOUT In each case, when a fault is encountered, the powergood output deasserts and the device drives GATE low. After a fault, the MAX5924A, MAX5924B, MAX5925A, and MAX5925B latch GATE low and the MAX5924C, MAX5924D, MAX5925C, and MAX5925D enter the autoretry mode. The MAX5926 has selectable latched or autoretry modes. Figure 7 shows the slow comparator response to an overcurrent fault. PGOOD* CL = LARGE IINRUSH CL = SMALL PGOOD** I PROBE ILOAD ILOAD VGATE tPROBE < tLP VTHPGOOD Figure 5. Startup Waveform 3.0V TO 6.7V 14 VOUT 12 RLP (Ω) MAX5924/MAX5925/MAX5926 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor 10 8 ILIM ILOAD 6 tCBS VCC = VS 4 2 4 6 8 10 12 14 VCC (V) Figure 6. Load-Probe Resistance vs. Supply Voltage 12 *MAX5924B, MAX5924D, MAX5925B, MAX5925D, AND MAX5926 ONLY. **MAX5924A, MAX5924C, MAX5925A, MAX5925C, AND MAX5926 ONLY. Figure 7. Slow Comparator Response to an Overcurrent Fault ______________________________________________________________________________________ 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor Slow Comparator The slow comparator is disabled during startup while the external MOSFET turns on. If the slow comparator detects an overload condition while in normal operation (after startup is complete), it turns off the external MOSFET by discharging the gate capacitance with I GATE,PD . The magnitude of I GATE,PD depends on the external MOSFET gate-to-source voltage, VGS. The discharge current is strongest immediately following a fault and decreases as the MOSFET gate is discharged (Figure 8a). LATCH FAULT MANAGEMENT Low Autoretry mode High Latched mode Fast Comparator The fast comparator is used for serious current overloads or short circuits. If the load current reaches the fast comparator threshold, the device quickly forces the MOSFET off. The fast comparator has a response time of 280ns, and discharges GATE with IGATE,PD (Figure 8a). The fast comparator is disabled during startup when no RSENSE is detected Latched and Autoretry Fault Management The MAX5924A, MAX5924B, MAX5925A, and MAX5925B latch the external MOSFET off when an overcurrent fault is detected. Following an overcurrent fault, the MAX5924C, MAX5924D, MAX5925C, and MAX5925D enter autoretry mode. The MAX5926 can be configured for either latched or autoretry mode (see Table 1). In autoretry, a fault turns the external MOSFET off then automatically restarts the device after the autoretry delay, tRETRY. During the autoretry delay, pull EN or EN1 low to restart the device. In latched mode, pull EN or EN1 low for at least 100µs to clear a latched fault and restart the device. Power-Good Outputs The power-good output(s) are open-drain output(s) that deassert: • When VCC < VUVLO 60 VCC = 13.2V • During tD,UVLO • When VGS < VTHPGOOD • During load probing • When disabled (EN = GND (MAX5924/MAX5925), EN1 = GND or EN2 = high (MAX5926)) • During fault management 50 IGATE, PD (mA) Table 1. Selecting Fault Management Mode (MAX5926) 40 30 20 • During t RETRY or when latched off (MAX5924A, MAX5924B, MAX5925A, MAX5925B, or MAX5926 (LATCH = low)). 10 0 0 1 2 3 4 5 6 7 VGS (V) PGOOD/PGOOD asserts only if the part is in normal mode and no faults are present. Figure 8a. Gate Discharge Current vs. MOSFET Gate-to-Source Voltage ______________________________________________________________________________________ 13 MAX5924/MAX5925/MAX5926 Bilevel Fault Protection Bilevel Fault Protection in Startup Mode Bilevel fault protection is disabled in startup mode, and is enabled when VGATE-VOUT exceeds VCB,EN at the end of the startup period. When no RSENSE is detected, neither slow nor fast comparator is active during startup because the high RD(ON) of the MOSFET when not fully enhanced would signal an artificially-high VIN-VSENSE voltage. Load probing prior to startup insures that the output is not short circuited. When RSENSE is detected, the slow comparator is disabled during startup while the fast comparator remains active. The overcurrent trip level is higher than normal during the startup period because the ICB is temporarily doubled to ICB,SU at this time. This allows higher than normal startup current to allow for output capacitor charging current. Undervoltage Lockout (UVLO) UVLO circuitry prevents the MAX5924/MAX5925/ MAX5926 from turning on the external MOSFET until VCC exceeds the UVLO threshold, VUVLO, for tD,UVLO. UVLO protects the external MOSFET from insufficient gate-drive voltage, and tD,UVLO ensures that the board is fully plugged into the backplane and VCC is stable prior to powering the hot-swapped system. Any input voltage transient at VCC below the UVLO threshold for more than the UVLO deglitch period, tDG, resets the device and initiates a startup sequence. Device operation is protected from momentary input-voltage steps extending below the UVLO threshold for a deglitch period, tDG. However, the power-good output(s) may momentarily deassert if the magnitude of a negative step in VCC exceeds approximately 0.5V, and VCC drops below VUVLO. Operation is unaffected and the power-good output(s) assert(s) within 200µs as shown in Figure 8b. This figure also shows that if the UVLO condition exceeds tDG = 900µs (typ), the power-good output(s) again deassert(s) and the load is disconnected. Determining Inrush Current Determining a circuit’s inrush current is necessary to choose a proper MOSFET. The MAX5924/MAX5925/ MAX5926 regulate the inrush current by controlling the output-voltage slew rate, but inrush current is also a function of load capacitance. Determine an anticipated inrush current using the following equation: dVOUT = CL × SR dt × 1000 IINRUSH(A) = CL where CL is the load capacitance in µF and SR is the selected MAX5924/MAX5925/MAX5926 output slew rate in V/ms. For example, assuming a load capacitance of 100µF and using the value of SR = 10V/ms, the anticipated inrush current is 1A. If a 16V/ms output slew rate is used, the inrush current increases to 1.6A. Choose SR so the maximum anticipated inrush current does not trip the fast circuit-breaker comparator during startup. Slew Rate The MAX5924/MAX5925/MAX5926 limit the slew rate of VOUT. Connect an external capacitor, CSLEW, between SLEW and GND to adjust the slew-rate limit. Floating SLEW sets the maximum slew rate to the minimum value. Calculate CSLEW using the following equation: CSLEW = 330 10-9 / SR where, SR is the desired slew rate in V/ms and CSLEW is in nF. This equation is valid for CSLEW ≥ 100nF. For higher SR, see the Typical Operating Characteristics. A 2µA (typ) pullup current clamped to 1.4V causes an initial jump in the gate voltage, VGATE, if CGATE is small and the slew rate is slow (Figure 3). Figure 9 illustrates how the addition of gate capacitance minimizes this initial jump. CGATE should not exceed 25nF. VS = VCC = 13.2V CSLEW = 1µF CL = 10µF GATE 2V/div VCC 1V/div VGATE MAX5924/MAX5925/MAX5926 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor MOSFET ONLY 5V/div MOSFET AND CGATE = 20nF 0V PGOOD 200µs/div Figure 8b. PGOOD Behavior with Large Negative Input-Voltage Step when VS is Near VS(MIN) 14 0V 1V/div 10ms/div Figure 9. Impact of CGATE on the VGATE Waveform ______________________________________________________________________________________ 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor The enable comparators control the on/off function of the MAX5924/MAX5925/MAX5926. Enable is also used to reset the fault latch in latch mode. Pull EN or EN1 low for 100µs to reset the latch. A resistive divider between EN or EN1, VS, and GND sets the programmable turnon voltage to a voltage greater than VUVLO (Figure 10). Selecting a Circuit-Breaker Threshold The MAX5924/MAX5925/MAX5926 offer a circuit-breaker function to protect the external MOSFET and the load VS RCB R1 VCC CB GATE SENSE OUT EN (EN1) R2 MAX5924_ MAX5925_ MAX5926 RSC SC_DET (EN2) GND ( ) ARE FOR MAX5926 ONLY. VS,TURN-ON = (R2 + R1) VEN/UVLO R2 from the potentially damaging effects of excessive current. As load current flows through RDS(ON) (Figure 12) or RSENSE (Figure 13), a voltage drop is generated. After VGS exceeds VCB,EN, the MAX5924/MAX5925/ MAX5926 monitor this voltage to detect overcurrent conditions. If this voltage exceeds the circuit-breaker threshold, the external MOSFET turns off and the power-good output(s) deassert(s). To accommodate different MOSFETs, sense resistors, and load currents, the MAX5924/MAX5925/MAX5926 voltage across RCB can be set between 10mV and 500mV. The value of the circuit-breaker voltage must be carefully selected based on VS (Figure 11). No RSENSE Mode When operating without RSENSE, calculate the circuitbreaker threshold using the MOSFET’s RDS(ON) at the worst possible operating condition, and add a 20% overcurrent margin to the maximum circuit current. For example, if a MOSFET has an R DS(ON) of 0.06Ω at T A = +25°C, and a normalized on-resistance factor of 1.75 at TA = +105°C, the RDS(ON) used for calculation is the product of these two numbers, or (0.06Ω) x (1.75) = 0.105Ω. Then, if the maximum current is expected to be 2A, using a 20% margin, the current for calculation is (2A) x (1.2) = 2.4A. The resulting minimum circuit-breaker threshold is then a product of these two numbers, or (0.105Ω) x (2.4A) = 0.252V. Using this method to choose a circuit-breaker threshold allows the circuit to operate under worst-case conditions without causing a circuitbreaker fault, but the circuit-breaker function will still detect a short circuit or a gross overcurrent condition. Figure 10. Adjustable Turn-On Voltage 15,000 15,000 TC = 0ppm/°C 12,000 12,000 9000 6000 VS = 1.4V VS = 1.3V 9000 VS = 1.3V 6000 VS = 1.2V 3000 VS = 1.5V VS = 1.4V RCB(MAX) (Ω) RCB(MAX) (Ω) VS = 1.5V TC = 3300ppm/°C VS = 1.1V 3000 VS = 1.2V VS = 1.1V VS = 1.0V VS = 1.0V 0 0 -40 -15 10 35 60 85 TEMPERATURE (°C) -40 -15 10 35 60 85 TEMPERATURE (°C) Figure 11. Maximum Circuit-Breaker Programming Resistor vs. Temperature ______________________________________________________________________________________ 15 MAX5924/MAX5925/MAX5926 EN (MAX5924/MAX5925), EN1/EN2 (MAX5926) MAX5924/MAX5925/MAX5926 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor To determine the proper circuit-breaker resistor value use the following equation, which refers to Figure 12: RCB = (ITRIPSLOW x RDS(ON)( T)) + VCB ,OS ICB where ITRIPSLOW is the desired slow-comparator trip current. The fast-comparator trip current is determined by the selected RCB value and cannot be adjusted independently. The fast-comparator trip current is given by: ITRIPFAST = ICB x (RCBF + RCB) ± VCB ,OS RDS(ON)( T) SC_DET must be connected to OUT through the selected RSC when not using RSENSE. RSENSE Mode When operating with R SENSE , calculate the circuitbreaker threshold using the worst possible operating conditions, and add a 20% overcurrent margin to the maximum circuit current. For example, with a maximum expected current of 2A, using a 20% margin, the current for calculation is (2A) x (1.2) = 2.4A. The resulting minimum circuit-breaker threshold is then a product of this current and RSENSE = 0.06Ω, or (0.06Ω) x (2.4A) = 0.144V. Using this method to choose a false circuitbreaker threshold allows the circuit to operate under worst-case conditions without causing a circuit-breaker fault, but the circuit-breaker function will still detect a short-circuit or a gross overcurrent condition. To determine the proper circuit-breaker resistor value, use the following equation, which refers to Figure 13: (ITRIPSLOW RCB = x RSENSE) + VCB ,OS ICB where, ITRIPSLOW is the desired slow-comparator trip current. The fast-comparator trip current is determined by the selected RCB value and cannot be adjusted independently. The fast-comparator trip current is given by: ITRIPFAST = ICB x (RCBF + RCB) ± VCB ,OS RSENSE SC_DET should be connected to V CC when using RSENSE. ILOAD ILOAD RDS(ON) RSENSE VS VS VOUT VOUT RCB RCB SENSE CB CB GATE SENSE OUT VCB,TH MAX5925 MAX5926 RCBF GATE VCB,TH SLOW COMPARATOR MAX5925 MAX5926 VCB,OS RCBF ICB VCB,OS VCBF,TH Figure 12. Circuit Breaker Using RDS(ON) 16 SLOW COMPARATOR VCB,OS FAST COMPARATOR FAST COMPARATOR TC SELECT OUT TC SELECT ICB VCB,OS VCBF,TH Figure 13. Circuit Breaker Using RSENSE ______________________________________________________________________________________ 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor Applications Information Component Selection n-Channel MOSFET Most circuit component values may be calculated with the aid of the MAX5924–MAX5926. The "Design calculator for choosing component values" software can be downloaded from the MAX5924–MAX5926 Quickview on the Maxim website. Select the external n-channel MOSFET according to the application’s current and voltage level. Table 3 lists some recommended components. Choose the MOSFET’s on-resistance, RDS(ON), low enough to have a minimum voltage drop at full load to limit the MOSFET power dissipation. High RDS(ON) can cause undesired power loss and output ripple if the board has pulsing loads or triggers an external undervoltage reset monitor at full load. Determine the device power-rating requirement to accommodate a short circuit on the board at startup with the device configured in autoretry mode. Using the MAX5924/MAX5925/MAX5926 in latched mode allows the consideration of MOSFETs with higher RDS(ON) and lower power ratings. A MOSFET can typically with- TC TCICB (ppm/°C) High 0 Low 3300 Table 3. Suggested External MOSFETs APPLICATION CURRENT (A) PART DESCRIPTION 1 International Rectifier IRF7401 SO-8 2 Siliconix Si4378DY SO-8 5 Siliconix SUD40N02-06 DPAK 10 Siliconix SUB85N02-03 D2PAK 50 45 VCB AND VSENSE (mV) ITRIPSLOW x RDS(ON)(T) ≥ ICB(T) x RCB + |VCB,OS| where VCB,OS is the worst-case offset voltage. Figure 14 graphically portrays operating conditions for a MOSFET with a 4500ppm/°C temperature coefficient. Table 2. Programming the Temperature Coefficient (MAX5926) VS = VCC = 13.2V, RCB = 672Ω, ITRIPSLOW = 5A, RDS(ON)(25) = 6.5mΩ CIRCUIT-BREAKER TRIP REGION (VSENSE ≥ VCB) 40 35 30 VSENSE = RDS(ON)(T) x ILOAD(MAX) (4500ppm/°C) 25 VCB = ICB(T) x RCB + VCB,OS (3300ppm/°C) 20 -40 -15 10 35 60 85 110 TEMPERATURE (°C) Figure 14. Circuit-Breaker Trip Point and Current-Sense Voltage vs. Temperature stand single-shot pulses with higher dissipation than the specified package rating. Low MOSFET gate capacitance is not necessary since the inrush current limiting is achieved by limiting the gate dv/dt. Table 4 lists some recommended manufacturers and components. Be sure to select a MOSFET with an appropriate gate drive (see the Typical Operating Characteristics ). Typically, for V CC less than 3V, select a 2.5V V GS MOSFET. ______________________________________________________________________________________ 17 MAX5924/MAX5925/MAX5926 Circuit-Breaker Temperature Coefficient In applications where the external MOSFET’s on-resistance is used as a sense resistor to determine overcurrent conditions, a 3300ppm/°C temperature coefficient is desirable to compensate for the RDS(ON) temperature coefficient. Use the MAX5926’s TC input to select the circuit-breaker programming current’s temperature coefficient, TCICB (see Table 2). The MAX5924 temperature coefficient is preset to 0ppm/°C, and the MAX5925’s is preset to 3300ppm/°C. Setting TCICB to 3300ppm/°C allows the circuit-breaker threshold to track and compensate for the increase in the MOSFET’s RDS(ON) with increasing temperature. Most MOSFETs have a temperature coefficient within a 3000ppm/°C to 7000ppm/°C range. Refer to the MOSFET data sheet for a device-specific temperature coefficent. RDS(ON) and ICB are temperature dependent, and can therefore be expressed as functions of temperature. At a given temperature, the MAX5925/MAX5926 indicate an overcurrent condition when: MAX5924/MAX5925/MAX5926 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor Table 4. Component Manufacturers COMPONENT Sense Resistors MOSFETs MANUFACTURER PHONE Dale-Vishay 402-564-3131 IRC 828-264-8861 www.irctt.com Fairchild 888-522-5372 www.fairchildsemi.com International Rectifier 310-233-3331 www.irf.com Optional Sense Resistor Select the sense resistor in conjunction with RCB to set the slow and fast circuit-breaker thresholds (see the Selecting a Circuit-Breaker Threshold section). The sense-resistor power dissipation depends on the device configuration. If latched mode is selected, PRSENSE = (IOVERLOAD)2 x RSENSE; if autoretry is selected, then P RSENSE = (I OVERLOAD ) 2 x R SENSE x (t ON /t RETRY ). Choose a sense-resistor power rating of twice the PRSENSE for long-term reliable operation. In addition, ensure that the sense resistor has an adequate I2T rating to survive instantaneous short-circuit conditions. No-Load Operation The internal circuitry is capable of sourcing a current at the OUT terminal of up to 120µA from a voltage VIN + VGS. If there is no load on the circuit, the output capacitor will charge to a voltage above VIN until the external MOSFET’s body diode conducts to clamp the capacitor voltage at VIN plus the body-diode VF. When testing or operating with no load, it is therefore recommended that the output capacitor be paralleled with a resistor of value: R = VX / 120µA where VX is the maximum acceptable output voltage prior to hot-swap completion. Design Procedure Given: • VCC = VS = 5V • CL = 150µF • Full-Load Current = 5A • No RSENSE • IINRUSH = 500mA Procedures: 1) Calculate the required slew rate and corresponding CSLEW: I V SR = INRUSH = 3.3 1000 × CL ms 18 WEBSITE www.vishay.com CSLEW = 330 × 10 −9 330 × 10 −9 = = 0.1µF SR 3.3 V ms 2) Select a MOSFET and determine the worst-case power dissipation. 3) Minimize power dissipation at full load current and at high temperature by selecting a MOSFET with an appropriate RDS(ON). Assume a 20°C temperature difference between the MAX5924/MAX5925/ MAX5926 and the MOSFET. For example, at room temperature the IRF7822’s RDS(ON) = 6.5mΩ. The temperature coefficient for this device is 4000ppm/°C. The maximum RDS(ON) for the MOSFET at TJ(MOSFET) = +105°C is: ppm ⎞ ⎛ RDS(ON)105 = 6.5mΩ × ⎜1 + (105°C − 25°C) × 4000 ⎟ ⎝ °C ⎠ = 8.58mΩ The power dissipation in the MOSFET at full load is: PD = I2 R = (5A)2 × 8.58mΩ = 215mW 4) Select RCB. Since the MOSFET’s temperature coefficient is 4000ppm/°C, which is greater than TC ICB (3300ppm/°C), calculate the circuit-breaker threshold at high temperature so the circuit breaker is guaranteed not to trip at lower temperature during normal operation (Figure 15). ITRIPSLOW = IFULL LOAD + 20% = 5A + 20% = 6A RDS(ON)105 = 8.58mΩ (max), from step 2 ICB85 = 58µA x (1 + (3300ppm/°C x (85 - 25)°C) = 69.5µA (min) RCB = (ITRIPSLOW x RDS(ON)105 ICB85 ) + VCB,OS RCB = ((6A x 8.58mΩ) + 4.7mV)/69.5µA = 808Ω ______________________________________________________________________________________ 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor the two devices are equal, the circuit-breaker trip threshold is most accurate. Keep the MOSFET and the MAX5925/MAX5926 as close to each other as possible to facilitate thermal coupling. HIGH-CURRENT PATH SENSE RESISTOR RCB MAX5924 MAX5925 MAX5926 Figure 15. Kelvin Connection for the Current-Sense Resistor Selector Guide POWER-GOOD OUTPUT CIRCUIT-BREAKER TEMPCO (ppm/°C) FAULT MANAGEMENT MAX5924A 0 MAX5924B 0 MAX5924C PGOOD (OPEN-DRAIN) PGOOD (OPEN-DRAIN) Latched ✓ — Latched — ✓ 0 Autoretry ✓ — MAX5924D 0 Autoretry — ✓ MAX5925A 3300 Latched ✓ — MAX5925B 3300 Latched — ✓ MAX5925C 3300 Autoretry ✓ — MAX5925D 3300 Autoretry — ✓ 0 or 3300 (Selectable) Latched or Autoretry (Selectable) ✓ ✓ PART MAX5926 ______________________________________________________________________________________ 19 MAX5924/MAX5925/MAX5926 Layout Considerations Keep all traces as short as possible and maximize the high-current trace dimensions to reduce the effect of undesirable parasitic inductance. Place the MAX5924/ MAX5925/MAX5926 close to the card’s connector. Use a ground plane to minimize impedance and inductance. Minimize the current-sense resistor trace length (<10mm), and ensure accurate current sensing with Kelvin connections. When the output is short circuited, the voltage drop across the external MOSFET becomes large. Hence, the power dissipation across the switch increases, as does the die temperature. An efficient way to achieve good power dissipation on a surface-mount package is to lay out two copper pads directly under the MOSFET package on both sides of the board. Connect the two pads to the ground plane through vias, and use enlarged copper mounting pads on the top side of the board. It is important to maximize the thermal coupling between the MOSFET and the MAX5925/MAX5926 to balance the device junction temperatures. When the temperatures of 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor MAX5924/MAX5925/MAX5926 Pin Configurations TOP VIEW VCC 1 16 CB SC_DET 2 VCC 1 SC_DET 2 EN 3 PGOOD (PGOOD) GND 10 CB 9 SENSE 8 OUT 4 7 GATE 5 6 SLEW MAX5924 MAX5925 GND 5 9 Chip Information TRANSISTOR COUNT: 3751 PROCESS: BiCMOS N VOUT Package Information SENSE GATE OUT VCC MAX5924 MAX5926 For the latest package outline information and land patterns, 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 DOCUMENT NO. 10 µMAX U10CN+1 21-0061 16 QSOP-EP E16E-1 21-0112 SEE FIGURE 2 FOR A DETAILED TYPICAL OPERATING CIRCUIT WITH RSENSE. 20 TC QSOP 2.25V TO 13.2V GND 10 N.C. LATCH 8 RCB GND 11 N.C. EP TYPICAL OPERATION WITH RSENSE REMOVABLE CARD RSENSE 1V TO VCC CB 12 SLEW EN2 6 Typical Operating Circuits (continued) VCC 13 GATE MAX5926 PGOOD 7 ( ) FOR THE MAX5924A, MAX5924C, MAX5925A, AND MAX5925C. VS 14 OUT EN1 3 PGOOD 4 µMAX BACKPLANE 15 SENSE ______________________________________________________________________________________ 1V to 13.2V, n-Channel Hot-Swap Controllers Require No Sense Resistor REVISION NUMBER REVISION DATE 0 8/05 Initial release 1 6/06 Revised data sheet title, General Description, Features, EC table, Typical Operating Circuit, and added No-Load Operation section. 1–13, 15–18 2 10/06 Initial release of MAX5924BEUB and revised EC table. 1–4, 10–12 3 4/10 Revised EC table. DESCRIPTION PAGES CHANGED — 2–4 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 21 © 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX5924/MAX5925/MAX5926 Revision History