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19-3282; Rev 1; 7/04
Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity
General Description
The MAX5934/MAX5934A are fully integrated hot-swap controllers for +9V to +80V (MAX5934A) positive supply rails. The MAX5934 is optimized for +33V to +80V power-supply rails. These devices allow for the safe insertion and removal of circuit cards into a live backplane without causing glitches on the backplane power-supply rail. The MAX5934/MAX5934A feature a programmable analog foldback current limit, programmable undervoltage lockout, and programmable output-voltage slew rate through an external n-channel MOSFET. In addition, if these devices remain in current limit for more than a programmable time, the external n-channel MOSFET latches off. The MAX5934/MAX5934A feature pin-selectable PWRGD_ assertion polarity (active low or active high) and pin-selectable fault management (latched or autoretry). Other features include automatic restart after a circuit-breaker fault, selectable duty-cycle (DC) options, and thermal-shutdown mode for overtemperature protection. The MAX5934/MAX5934A operate in the extended (-40C to +85C) temperature range and are available in a 16-pin QSOP package.
Features
Provides Safe Hot Swap for +9V to +80V Power Supplies (MAX5934A) Safe Board Insertion and Removal from a Live Backplane Pin-Selectable Active-Low or Active-High PowerGood Output Pin-Selectable Latched or Autoretry Fault Management Programmable Foldback Current Limiting High-Side Drive for an External N-Channel MOSFET Built-In Thermal Shutdown Undervoltage Lockout (UVLO) Pin-Selectable Duty-Cycle Options (0.94%, 1.88%, 3.75%)
MAX5934/MAX5934A
Ordering Information
PART MAX5934EEE MAX5934AEEE TEMP RANGE -40C to +85C -40C to +85C PIN-PACKAGE 16 QSOP 16 QSOP
Applications
Hot Board Insertion Electronic Circuit Breakers Industrial High-Side Switch/Circuit Breakers Network Routers and Switches 24V/48V Industrial/Alarm Systems
TOP VIEW
LATCH/RETRY 1 ON 2 POL_SEL 3 FB1 4 16 VCC 15 DC 14 SENSE
Pin Configuration
Typical Application Circuit appears at end of data sheet.
PWRGD2 5 PWRGD1 6 PWRGD3 7 GND 8
MAX5934 MAX5934A
13 N.C. 12 FB2 11 GATE 10 TIMER 9 OUT
QSOP
Selector Guide
PART MAX5934 MAX5934A DEFAULT UVLO (V) 31 8.3 SUPPLY VOLTAGE RANGE (V) +33 to +80 +9 to +80 LATCHED/ AUTORETRY FAULT PROTECTION Pin-selectable Pin-selectable DUTY CYCLE Pin-selectable Pin-selectable PWRGD_ OUTPUT LOGIC Pin-selectable Pin-selectable
________________________________________________________________ Maxim Integrated Products
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity MAX5934/MAX5934A
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to GND.) VCC .........................................................................-0.3V to +85V SENSE, FB_, ON.........................................-0.3V to (VCC + 0.3V) TIMER, PWRGD_, DC, LATCH/RETRY, POL_SEL ....-0.3V to +85V GATE ......................................................................-0.3V to +95V OUT ................................................(VGATE - 14V) to the lower of (VGATE + 0.3V) and (VCC + 0.3V) Maximum GATE Current ....................................-50mA, +150mA Maximum Current into Any Other Pin................................50mA Continuous Power Dissipation (TA = +70C) 16-Pin QSOP (derate 8.3mW/C above +70C)...........667mW Operating Temperature Range ...........................-40C to +85C Maximum Junction Temperature .....................................+150C Storage Temperature Range .............................-60C to +150C ESD Rating (Human Body Model)......................................2000V Lead Temperature (soldering, 10s) .................................+300C
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 = +24V (MAX5934A), VCC = +48V (MAX5934), GND = 0V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Supply Voltage Range Supply Current VCC Undervoltage Lockout VCC Undervoltage-Lockout Hysteresis FB1 High-Voltage Threshold FB2 High-Voltage Threshold FB1 Low-Voltage Threshold FB2 Low-Voltage Threshold FB_ Hysteresis FB_ Input Bias Current FB1 Threshold Line Regulation FB2 Threshold Line Regulation SENSE Trip Voltage (VCC - VSENSE) GATE Pullup Current GATE Pulldown Current (VGATE - VCC) at PWRGD3 Assertion External N-Channel Gate Drive TIMER Pullup Current SYMBOL VCC ICC VLKO VLKOHYST VFB1H VFB2H VFB1L VFB2L VFBHYST IINFB VFB1 VFB2 VSENSETRIP IGATEUP IGATEDN VFB_ = 0V VCC(MIN) VCC 80V, MAX5934A, ON = 0V VCC(MIN) VCC 80V, MAX5934A, ON = 0V VFB_ = 0V, TA = 0C to +70C VFB_ = 1V, TA = 0C to +70C Charge pump on, VGATE = 7V Any fault condition, VGATE = 2V 8 39 -5 35 3.8 10 4.5 10 -24 12 47 -10 70 4.3 13.6 13.6 13.6 -75 -1 CONDITIONS MAX5934A MAX5934 VON = 3V, VCC = 80V VCC low-to-high transition MAX5934A MAX5934 FB1 low-to-high transition FB2 low-to-high transition FB1 high-to-low transition FB2 high-to-low transition 1.280 1.280 1.221 1.202 80 +1 0.05 0.05 17 55 -20 100 5 18 18.0 18 -120 A V MAX5934A MAX5934 MIN 9 33 1.4 7.5 29.5 8.3 31 0.4 2 1.313 1.313 1.233 TYP MAX 80 80 3.5 8.8 32.5 UNITS V mA V V 1.345 1.345 1.245 1.264 V V V V mV A mV/V mV/V mV A mA V
VGATEPWRGD3 VGATE - VCC, low-to-high transition VGATE - VCC, MAX5934 VGATE ITIMERUP VGATE - VCC, MAX5934A VTIMER = 0V VCC = 10.8V to 20V VCC = 20V to 80V
2
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +24V (MAX5934A), VCC = +48V (MAX5934), GND = 0V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER TIMER Pulldown Current ON High Threshold ON Low Threshold ON Hysteresis ON Input Bias Current LATCH/RETRY and POL_SEL Low-Voltage Threshold LATCH/RETRY and POL_SEL High-Voltage Threshold LATCH/RETRY and POL_SEL Input Current Source GATE Clamp Voltage PWRGD_ Output Low Voltage PWRGD_ Leakage Current Thermal Shutdown Thermal-Shutdown Hysteresis SENSE Input Bias Current DC High-Voltage Threshold 1 DC High-Voltage Threshold 2 DC High-Voltage Threshold 1 Hysteresis DC High-Voltage Threshold 2 Hysteresis DC Input Open-Circuit Voltage DC Input Impedance DC Input Current ON Low-to-GATE Low Propagation Delay ON High-to-GATE High Propagation Delay ISENSE VDCHTH VDCLTH VDCLHYS VDCLHYS VDCOC RDC_IN IDC_IN tPHLON tPLHON V_DC = 80V V_DC = 0V CGATE = 0, Figures 1 and 2 CGATE = 0, Figures 1 and 2 VSENSE = 0 to VCC Rising edge, DC transition from 3.75% to 1.88% Rising edge, DC transition from 0.94% to 3.75% -1 2.150 1.075 2.600 1.250 45 45 1.9 57 50 -34 6 1.7 SYMBOL ITIMERON VONH VONL VONHYST IINON VLRIL, VPOS_SEL_IL VLRIH, VPOS_SEL_IH ILR_IN, IPOS_SEL_IN VSGZ VOL IOH VPOL_SEL = 80V VPOL_SEL = 0V VGATE - VOUT IO = 2mA IO = 4mA VPWRGD_ = 80V Temperature rising +150 20 +3 2.850 1.425 15 4.5 -37 16.4 19 0.4 2.5 10 VON = 0V -1 0.4 3.2 VTIMER = 1V CONDITIONS DC = 3.75%, DC = floating DC = 1.88%, DC = high DC = 0.94%, DC = low ON low-to-high transition ON high-to-low transition MIN 1.5 0.75 0.37 1.280 1.221 TYP 3 1.5 0.75 1.313 1.233 80 +1 MAX 4.5 2.25 1.12 1.355 1.245 V V mV A V V A V V A C C A V V mV mV V k A s s A UNITS
MAX5934/MAX5934A
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity MAX5934/MAX5934A
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +24V (MAX5934A), VCC = +48V (MAX5934), GND = 0V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER FB_ Low-to-PWRGD_ Low Propagation Delay FB_ High-to-PWRGD_ High Propagation Delay (VCC - VSENSE) High-to-GATE Low Propagation Delay SYMBOL tPHLFB_ tPLHFB_ tPHLSENSE Figures 1, 3 Figures 1, 3 TA = +25C, CGATE = 0, Figures 1 and 4 0.5 CONDITIONS MIN TYP 3.2 1.5 1.8 2.5 MAX UNITS s s s
Note 1: All currents into the device are positive and all currents out of the device are negative. All voltages are referenced to ground, unless noted otherwise.
Test Circuit and Timing Diagrams
ON LATCH/ RETRY POL_SEL FB1 VCC DC OUT SENSE ON 1.313V tPLHON GATE 5V 1.233V tPHLON 1V
5V 5V 5V
5k PWRGD2 5k PWRGD1 5k PWRGD3 GND
MAX5934 MAX5934A
FB2 GATE TIMER N.C.
Figure 1. Test Circuit
Figure 2. ON-to-GATE Timing
1.313V FB tPLHFB PWRGD 1V
1.233V tPHLFB 1V
VCC - SENSE GATE
47mV tPHLSENSE VCC
Figure 3. FB_-to-PWRGD_ Timing 4
Figure 4. SENSE-to-GATE Timing
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity
Typical Operating Characteristics
(VCC = +48V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX5934 toc01
MAX5934/MAX5934A
SUPPLY CURRENT vs. TEMPERATURE
MAX5934 toc02
FB_ LOW-VOLTAGE THRESHOLD vs. TEMPERATURE
1.245 1.240 1.235 1.230 1.225 1.220 1.215 1.210 1.205
MAX5934 toc03
2.7 2.4 2.1 1.8 ICC (mA) 1.5 1.2 0.9 0.6 0.3 0 33 40 48 56 VCC (V) 64 72 TA = -40C TA = +85C TA = +25C
3.0 2.5 2.0 ICC (mA) VCC = 48V 1.5 1.0 VCC = 33V 0.5 0
1.250 FB_ LOW-VOLTAGE THRESHOLD (V)
1.200 -40 -15 10 35 60 85 -40 -15 10 35 60 85 TEMPERATURE (C) TEMPERATURE (C)
80
FB_ HIGH-VOLTAGE THRESHOLD vs. TEMPERATURE
MAX5934 toc04
FB_ HYSTERESIS vs. TEMPERATURE
MAX5934 toc05
IGATE PULLUP CURRENT vs. TEMPERATURE
-6 IGATE PULLUP CURRENT (A) -7 -8 -9 -10 -11 -12 -13 -40 -15 10 35 60 85
MAX5934 toc06
1.335 FB_ HIGH-VOLTAGE THRESHOLD (V) 1.330 1.325 1.320 1.315 1.310 1.305 1.300 1.295 1.290 1.285 1.280 -40 -15 10 35 60
0.11 0.10 FB_ HYSTERESIS (V) 0.09 0.08 0.07 0.06 0.05 0.04
-5
85
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
GATE DRIVE vs. TEMPERATURE
16 GATE DRIVE (VGATE - VCC) (V) 15 14 13 12 11 10 9 8 7 -40 -15 10 35 60 85 TEMPERATURE (C) VCC = +33V VCC = +48V
MAX5934 toc07
GATE DRIVE vs. SUPPLY VOLTAGE
MAX5934 toc08
17
17 16 GATE DRIVE (VGATE - VCC) (V) 15 14 13 12 11 10 32 40 48 56 VCC (V) 64 72
80
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity MAX5934/MAX5934A
Typical Operating Characteristics (continued)
(VCC = +48V, TA = +25C, unless otherwise noted.)
TIMER PULLUP CURRENT vs. TEMPERATURE
MAX5934 toc09
TIMER PULLUP CURRENT vs. SUPPLY VOLTAGE
MAX5934 toc10
ON HIGH-VOLTAGE THRESHOLD vs. TEMPERATURE
MAX5934 toc11
-60 -65 -70 -75 -80 -85 -90 -40 -15 10 35 60
-73 -74 TA = +25C -75 -76 -77 -78 -79 TA = -40C TA = +85C
1.343 ON HIGH-VOLTAGE THRESHOLD (V) 1.333 1.323 1.313 1.303 1.293 1.283
TIMER PULLUP CURRENT (A)
TIMER PULLUP CURRENT (A)
85
33
40
48
56 VCC (V)
64
72
80
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
ON LOW-VOLTAGE THRESHOLD vs. TEMPERATURE
MAX5934 toc12
ON HYSTERESIS vs. TEMPERATURE
MAX5934 toc13
1.265 ON LOW-VOLTAGE THRESHOLD (V) 1.255 1.245 1.235 1.225 1.215 1.205 -40 -15 10 35 60
0.080
0.078 ON HYSTERESIS (V)
0.076
0.074
0.072 VCC = +48V 0.070 85 -40 -15 10 35 60 85 TEMPERATURE (C) TEMPERATURE (C)
PWRGD_ OUTPUT VOLTAGE LOW vs. LOAD CURRENT
MAX5934 toc14
SENSE REGULATION VOLTAGE vs. FB_ VOLTAGE
SENSE REGULATION VOLTAGE (mV) 45 40 35 30 25 20 15 10 5 0
MAX5934 toc15
20 18 16 PWRGD_ VOUT LOW (V) 14 12 10 8 6 4 2 0 10 30 50 ILOAD (mA) 70 TA = +85C TA = +25C TA = -40C
50
90
0
0.2
0.4
0.6
0.8
1.0
VFB (V)
6
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity
Pin Description
PIN 1 NAME LATCH/ RETRY ON POL_SEL FUNCTION Circuit-Breaker Fault-Management Select Input. Connect LATCH/RETRY to GND to latch off after a circuitbreaker fault. Leave LATCH/RETRY open or drive to logic-high voltage for automatic restart after a circuitbreaker fault. On/Off Control Input. ON implements the undervoltage-lockout threshold and resets the part after a fault latch (see the Fault Management (LATCH/RETRY) section). PWRGD_ Polarity Select Input. Leave POL_SEL open or drive to logic-high voltage for PWRGD_ asserted high. Connect POL_SEL to GND for PWRGD_ asserted low. Power-Good Comparator Input. Connect a resistive divider between output, FB1, and GND to monitor the output voltage (see the Power-Good (PWRGD_ ) Detection section). FB1 is also used as feedback for the current-limit foldback function. Open-Drain Power-Good Output. POL_SEL determines the output polarity of PWRGD2. PWRGD2 is asserted when FB2 is higher than VFB2H. PWRGD2 deasserts when FB2 is lower than VFB2L (see the Power-Good (PWRGD_) Detection section). Open-Drain Power-Good Output. POL_SEL determines the output polarity of PWRGD1. PWRGD1 is asserted when FB1 is higher than VFB1H. PWRGD1 deasserts when FB1 is lower than VFB1L (see the Power-Good (PWRGD_) Detection section). Open-Drain Power-Good Output. POL_SEL determines the output polarity of PWRGD3. PWRGD3 asserts when GATE is at maximum voltage. PWRGD3 deasserts after the timeout following an overcurrent event (see the Power-Good (PWRGD_) Detection section). Ground Output Voltage. OUT is used as the return path for the internal GATE protection clamping circuitry. Timing Input. Connect a capacitor from TIMER to GND to program the maximum time the part is allowed to remain in current limit (see the TIMER section). Gate-Drive Output. The high-side gate drive for the external n-channel MOSFET (see the GATE section). Noninverting Comparator Input. FB2 is used to monitor any other voltage in the system. When FB2 rises higher than VFB2H, PWRGD2 asserts. When FB2 drops below VFB2L, PWRGD2 deasserts. No Connection. Not internally connected. Current-Sense Input. Connect a sense resistor from VCC to SENSE and the drain of the external n-channel MOSFET. Duty-Cycle Select. When DC is floating, the default duty cycle is 3.75%. Connect DC to VCC to set the duty cycle to 1.88%. Connect DC to GND to set the duty cycle to 0.94%. Power-Supply Input. Bypass VCC to GND with a 0.1F capacitor. The input voltage range is from +9V to +80V for the MAX5934A and +33V to +80V for the MAX5934.
MAX5934/MAX5934A
2 3
4
FB1
5
PWRGD2
6
PWRGD1
7 8 9 10 11 12 13 14 15 16
PWRGD3 GND OUT TIMER GATE FB2 N.C. SENSE DC VCC
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity MAX5934/MAX5934A
Functional Diagram
FB1 VCC SENSE
MAX5934 MAX5934A
VP VP GEN REF GEN CHARGE PUMP AND GATE DRIVER
4.3V OPEN DRAIN
PWRGD3
GATE
GATE
OUT
PWRGD1
OPEN DRAIN
FB2
PWRGD2 1.233V ON VCC OPEN DRAIN PWRGD_ POLARITY SELECT POL_SEL
VUVLO
LOGIC
VP
0.5V
CIRCUITBREAKER FAULTMANAGEMENT SELECT
LATCH/RETRY
75A
DUTY CYCLE
DC
1.233V
TIMER ITIMERON GND
8
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity
Detailed Description
The MAX5934/MAX5934A are fully integrated hot-swap controllers for positive supply rails. These devices allow for the safe insertion and removal of circuit cards into live backplanes without causing glitches on the backplane power-supply rail. During startup, the MAX5934/ MAX5934A act as current regulators using an external sense resistor and MOSFET to limit the amount of current drawn by the load. The MAX5934A operates from a +9V to +80V supply voltage range and has a default UVLO set to +8.3V. The MAX5934 operates from a +33V to +80V supply voltage range and has a default UVLO set to +31V. The UVLO threshold is adjustable using a resistive divider connected from VCC to ON to GND (see R2 and R3 in Figure 5). The MAX5934/MAX5934A monitor input voltage, output voltage, output current, and die temperature. These devices feature three power-good outputs (PWRGD_) to indicate status by monitoring the voltage at FB1, FB2, and GATE (see the Power-Good (PWRGD_) Detection section). PWRGD1 indicates an output-voltage status, PWRGD2 can be used to indicate an overvoltage condition on the main power-supply rail, and PWRGD3 asserts when GATE voltage has charged to 4.3V above the supply rail. PWRGD3 deasserts when the TIMER voltage exceeds a 1.233V threshold in response to an extended fault condition. The MAX5934/MAX5934A control gate voltage on the external MOSFET to limit load current at startup and at overload to a value determined as:
MAX5934/MAX5934A
VIN RSENSE 0.025 R1 1k, 5% C1 10nF R2 49.9k 1% 2 R3 3.4k 1% 10 CTIMER 0.68F VCC 1 LATCH/RETRY TIMER FB1 4 16 VCC ON 14 SENSE 11 GATE OUT 9 RG 10 5%
M1 IRF530
R4 59k 1% R5 3.57k 1%
R6 24k 5%
R7 24k 5%
CL RL
MAX5934 MAX5934A
PWRGD1 PWRGD2 3 POL_SEL PWRGD3 6
PWRGD1 VCC 5 PWRGD2 7 VMONITOR 15 DC FB2 GND 8 12 R9 90k 1% R10 1k 1% PWRGD3
VCC
Figure 5. Application Circuit _______________________________________________________________________________________ 9
Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity MAX5934/MAX5934A
ILOAD = where: VSENSETRIP = VIN - VSENSE VSENSETRIP varies from a low of 12mV when the voltage at FB1 = 0V and increases to 47mV as the voltage at FB1 increases to 0.5V and beyond (see Figure 6). Thus, the current limit is low at a low output voltage, and increases as the output voltage reaches its final value. This gradually increases the limiting load current at startup and creates a foldback current limit under overload or short-circuit conditions. See Figure 5 for FB1 and RSENSE connections. VSENSETRIP RSENSE 1) TIMER's voltage goes below 0.5V 2) ON goes low When the current limit is not active, TIMER goes low by the I TIMERON current source. After the current limit becomes active, the ITIMEROFF pullup current source is connected to TIMER and the voltage rises with a slope of 75A/CTIMER as long as the current limit remains active. A capacitor from TIMER to GND (CTIMER) sets the desired current-limit timeout: TLIMIT = (CTIMER / 75A) x 1.233V
GATE
GATE provides a high-side gate drive for the external n-channel MOSFET. An internal charge-pump circuit guarantees at least 10V of gate drive for supply voltages higher than 20V (MAX5934A) and a 4.5V gate drive for supply voltages between 10.8V and 20V (MAX5934A) (for the MAX5934, see the Electrical Characteristics table). Connect an external capacitor from GATE to ground to set the rising slope of the voltage at GATE. The voltage at GATE is adjusted to maintain a constant voltage across RSENSE when the current limit is reached while the TIMER capacitor starts to charge. When the voltage at TIMER exceeds 1.233V, the voltage at GATE goes low. The MAX5934/MAX5934A monitor voltages at ON, VCC, and TIMER. GATE is pulled to GND whenever ON goes low, or the VCC supply voltage decreases below the UVLO threshold, or TIMER increases above the 1.233V threshold. Gate Voltage The Gate Drive vs. Supply Voltage graph in the Typical Operating Characteristics illustrates that GATE clamps to a maximum of 18V above the input voltage. The MAX5934 minimum gate-drive voltage is 10V at a minimum input-supply voltage of 33V. The MAX5934A minimum gate-drive voltage is 4.5V at a minimum supply of 10.8V. Therefore, a logic-level MOSFET must be used if the input supply is below 20V.
Power-Up Mode
During power-up, the MAX5934/MAX5934A gradually turn on the external n-channel MOSFETs. The MAX5934/MAX5934A monitor and provide current-limit protection to the load at all times. The current limit is programmable using an external current-sense resistor connected from V CC to SENSE. The MAX5934/ MAX5934A feature current-limit foldback and duty-cycle limit to ensure robust operation during load-fault and short-circuit conditions (see the Detailed Description and Overcurrent Protection sections).
TIMER
Connect an external capacitor from TIMER to ground to set the maximum overcurrent timeout limit. When the voltage at TIMER reaches 1.233V, GATE goes low and the 75A pullup current turns off (see the Functional Diagram). As a result, a preset pulldown current (ITIMERON) discharges the capacitor. To reset the internal fault latch, these two conditions must be met:
VCC - VSENSE
47mV
Fault Management (LATCH/RETRY)
The MAX5934/MAX5934A feature either latched-off or autoretry fault management configurable by the LATCH/RETRY input. To select automatic restart after a circuit-breaker fault, drive LATCH/RETRY high (above VLRIH) or leave it floating (see Figure 5).
12mV
0V
0.5V
VFB
Figure 6. Current-Limit Sense Voltage vs. Feedback Voltage 10 ______________________________________________________________________________________
Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity
In latch mode, the MAX5934/MAX5934A turn the MOSFET off and keep it off after an overcurrent fault. After the fault condition goes away and TIMER falls below 0.5V, recycle the power supplies or toggle ON low and high again to unlatch the device. In autoretry mode, the MAX5934/MAX5934A turn the MOSFET off after an overcurrent fault occurs. After the fault condition is removed, the device waits for TIMER to fall below 0.5V and then automatically restarts. If the fault is due to an overtemperature condition, the MAX5934/ MAX5934A wait for the die temperature to cool down below the +130C threshold before restarting. To adjust the UVLO threshold, connect an external resistive divider from VIN (or VCC) to ON and then from ON to GND. The following equation is used to calculate the new UVLO threshold: VUVLO_TH = VREF (1 + (R2 / R3)) where VREF is typically 1.233V.
MAX5934/MAX5934A
Applications Information
Hot-Circuit Insertion
The supply bypass capacitors on a circuit board can draw high peak currents from the backplane power bus as they charge when the circuit boards are inserted into a live backplane. This can cause permanent damage to the connector pins and glitch the system supply causing other boards in the system to reset. The MAX5934/MAX5934A are capable of controlling a board's power-supply voltage allowing for the safe insertion or removal of a board from a live backplane. These devices provide undervoltage and overcurrent protection and power-good output signals (PWRGD_).
Power-Good (PWRGD_ ) Detection
The MAX5934/MAX5934A feature three power-good outputs (PWRGD_) to indicate the status of three separate voltages. PWRGD_ asserts if the device detects an error condition. PWRGD_ is true when FB_ voltages exceed the low-tohigh threshold voltage (VFB_H). PWRGD_ is false when FB_ voltages go lower than the high-to-low threshold voltage (VFB_L). Connect external pullup resistors between PWRGD_ and OUT to pull up the PWRGD_ voltages to VOUT. PWRGD2 can be used to indicate an overvoltage condition on the main power-supply rail. PWRGD3 asserts when GATE voltage has charged to 4.3V above the supply rail. PWRGD3 deasserts when the TIMER voltage exceeds 1.233V threshold in response to an extended fault condition. The output polarity of PWRGD_ is determined by POL_SEL. Drive POL_SEL high or leave it floating to select PWRGD_ active high. Connect POL_SEL to GND for PWRGD_ active low.
Overcurrent Protection
The MAX5934/MAX5934A provide sophisticated overcurrent protection to ensure robust operation under outputcurrent-transient and overcurrent fault conditions. The current-protection circuit employs a foldback current limit and a short-circuit or excessive output-current protection. The MAX5934/MAX5934A offer a current foldback feature where the current folds back as a function of the output voltage that is sensed at FB1. As Figure 6 illustrates, the voltage across RSENSE decreases linearly when FB1 drops below 0.5V and stops at 12mV when VFB1 = 0V. The maximum current-limit equation is: ILIMIT = 47mV / RSENSE For RSENSE = 0.025, the current limit is set to 1.88A and goes down to 480mA at short circuit (output shorted to GND). In addition, the MAX5934/MAX5934A feature an adjustable overcurrent response time. The required time to regulate the MOSFET current depends on the input capacitance of the MOSFET, GATE capacitor (C1), compensation resistor (R1), and the internal delay from SENSE to GATE. Figure 7 shows the propagation delay from a voltage step at SENSE until GATE starts to fall, as a function of overdrive.
Undervoltage Lockout (UVLO)
The MAX5934A operates from a +9V to +80V supply voltage range and has a default UVLO set at +8.3V. The MAX5934 operates from a +33V to +80V supply voltage range and has a default UVLO set at +31V. The UVLO thresholds are adjustable using a resistive divider connected to VCC (see R2 and R3 in Figure 5). When the input voltage (or VCC) is below the UVLO threshold, the MOSFET is held off. When the input voltage (or V CC ) is above the UVLO threshold, the MAX5934/MAX5934A go into normal operation (or begin to turn on the external MOSFET).
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity MAX5934/MAX5934A
Undervoltage and Overvoltage Detection
RESPONSE TIME TO OVERCURRENT
14 12 PROPAGATION DELAY (s) 10 8 6 4 2 0 0 50 100 150 200 250 300 VCC - VSENSE (mV)
An undervoltage fault is detected when V ON goes below the trip point (VONL = 1.233V). When this occurs, GATE pulls low and stays low until VON rises above (VONH = 1.313V). An example of overvoltage protection is shown in Figure 8. Zener diode D1 turns on when VIN exceeds the diode's breakdown voltage and begins to pull TIMER high. When VTIMER goes higher than 1.233V, a fault is detected and GATE pulls low. As a result, Q1 turns off. Figure 9 shows overvoltage waveforms for VIN (see the Fault Management (LATCH/RETRY) section for restart conditions).
Supply Transient Protection
The MAX5934/MAX5934A are guaranteed to be safe from damage with supply voltages of up to 85V. Spikes at voltages above 85V may damage the part. Instantaneous short-circuit conditions, can cause large
Figure 7. Response Time to Overcurrent
VIN RSENSE 0.025 R1 1k 5% C1 10nF 16 VCC 2 ON 14 SENSE 11 GATE OUT 9 RG 10 5%
M1 IRF530
D1 30V 1N5256B R2 49.9k 1%
R3 3.4k 1% 10 CTIMER 0.68F VCC 1 LATCH/RETRY TIMER FB1 4
R4 59k 1% R5 3.57k 1%
R6 24k 5%
R7 24k 5%
R8 24k 5%
CL
MAX5934 MAX5934A
PWRGD1 PWRGD2 3 POL_SEL PWRGD3 6
PWRGD VCC 5 7 VMONITOR 15 DC FB2 GND 8 12 R9 90k 1% R10 1k 1%
VCC
Figure 8. Overvoltage Detection 12 ______________________________________________________________________________________
Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity MAX5934/MAX5934A
OVERVOLTAGE WAVEFORMS
IN 50V/div ISENSE 5A/div
GATE 50V/div TIMER 10V/div OUTPUT 50V/div 10s/div
IRF530
Figure 9. Overvoltage Waveforms
Figure 10. Recommended Layout for R2, R3, and RSENSE
changes in currents flowing through the power-supply traces. This can cause inductive voltage spikes that could exceed 85V. Use wider traces or heavier trace plating and connect a 0.1F capacitor between VCC and GND to minimize these inductive spikes. Use a transient voltage suppressor (TVS) at the input to prevent damage from voltage surges. An SMBJ54A is recommended.
Thermal Shutdown
If the MAX5934/MAX5934A die temperature reaches +150C, an overtemperature fault is generated. As a result, GATE goes low and turns the external MOSFET off. The MAX5934/MAX5934A die temperature must cool down below +120C before the overtemperature fault condition is removed.
Power-Up Sequence
At power-up, transistor Q1 (see the Typical Application Circuit) is off until these three conditions are met: * VON exceeds the turn-on threshold voltage * VCC exceeds the UVLO threshold * VTIMER stays below 1.233V The voltage at GATE increases with a slope of 10A/C1 (where C1 is shown in the Typical Application Circuit) and IINRUSH = CL x 10A / C1. When the voltage across RSENSE goes too high, the inrush current is limited by the internal current-limit circuitry that adjusts the GATE voltage to keep a constant voltage across RSENSE.
Board Layout and Bypassing
Kelvin connections are recommended for accurate current sensing. Make sure the minimum trace width for 2oz copper is 1.5mm per amp. A width of 4mm per amp is recommended. Connect a resistive divider from VCC to ON as close as possible to ON and have short traces from VCC and GND. To decrease induced noise connect a 0.1F capacitor between ON and GND (see Figure 10). The external MOSFET must be thermally coupled to the MAX5934/MAX5934A to ensure proper thermal shutdown operation.
______________________________________________________________________________________
13
Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity MAX5934/MAX5934A
Typical Application Circuit
VIN RSENSE 0.025 R1 1k 5% C1 10nF R2 49.9k 1% 16 VCC 2 ON 14 SENSE 11 GATE OUT 9 R4 59k 1% 10 CTIMER 0.68F VCC 1 LATCH/RETRY TIMER FB1 4 R5 3.57k 1% R6 24k 5% R7 24k 5% R8 24k 5% CL RG 10 5%
M1 IRF530
R3 3.4k 1% SMBJ54A
MAX5934 MAX5934A
PWRGD1 PWRGD2 3 POL_SEL PWRGD3 6
PWRGD VCC 5 7 VMONITOR 15 DC FB2 GND 8 GND 12 R9 90k 1% R10 1k 1%
VCC
Chip Information
TRANSISTOR COUNT: 1573 PROCESS: BiCMOS
14
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Positive High-Voltage, Hot-Swap Controllers with Selectable Fault Management and Status Polarity
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
QSOP.EPS
MAX5934/MAX5934A
PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH
21-0055
E
1
1
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 ____________________ 15 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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