EVALUATION KIT AVAILABLE MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy General Description Features The MAX14571/MAX14572/MAX14573 adjustable overvoltage- and overcurrent-protection devices are ideal to protect systems against positive and negative input voltage faults up to Q40V and feature low 100mI (typ) RON FETs. S Wide 4.5V to 36V Operating Input Range S Adjustable OVLO and UVLO Thresholds ±3% Accurate Preset Thresholds Automatic Internal and External Selection S Programmable Forward Current Limit Adjustable Current Limit Up to 4.2A ±15% Accuracy Limit The overvoltage-protector (OVP) feature protects voltages between 6V and 36V, while the undervoltage-protector (UVP) feature protects voltages between 4.5V and 24V. The overvoltage-lockout (OVLO) and undervoltage-lockout (UVLO) thresholds are set using optional external resistors. The factory-preset internal OVLO threshold is 33V (typ) and the preset internal UVLO threshold is 19.2V (typ). S 100mω (typ) On-Resistance FET S Dual-Enable Inputs High-Voltage-Capable Input, HVEN Microprocessor Input, EN The ICs also feature programmable current-limit protection up to 4.2A. Once current reaches the threshold, the MAX14571 turns off after the 20.7ms (typ) blanking time and stays off during the retry period. The MAX14572 latches off after the blanking time, and the MAX14573 limits the current continuously. In addition, these devices feature reverse current and thermal-shutdown protection. S Reverse Current Flow Control Input, RIEN S Thermal-Shutdown Protection Ordering Information PART The ICs are available in a small 14-pin TSSOP (5mm x 6.5mm) package and are specified over the extended -40NC to +85NC temperature range. TEMP RANGE PINOVERCURRENT PACKAGE PROTECTION MAX14571EUD+T -40NC to +85NC 14 TSSOPEP* Autoretry Applications MAX14572EUD+T -40NC to +85NC 14 TSSOPEP* Latchoff MAX14573EUD+T -40NC to +85NC 14 TSSOPEP* Continuous Industrial Equipment Consumer Electronics Marine Equipment Battery-Powered Applications +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed pad. Typical Operating Circuit VPOWER CIN IN OUT IN OUT OUT IN SYSTEM INPUT R3 MAX14571 MAX14572 MAX14573 R1 UVLO R4 R2 OVLO FLAG EN SET1 RIEN COUT VPULLUP SYSTEM HVEN GND NOTE: R1, R2, R3, AND R4 ARE ONLY REQUIRED FOR ADJUSTABLE OVLO/UVLO; OTHERWISE, CONNECT UVLO/OVLO TO GND. For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. 19-6470; Rev 1; 12/12 MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) IN, HVEN.................................................................-40V to +40V IN to OUT................................................................-40V to +40V OUT .......................................................................-0.3V to +40V OVLO, UVLO, FLAG, EN, RIEN.............................-0.3V to +6.0V Current into IN (DC Operating) (Note 1)............... ………….4.2A SETI........................... ………….-0.3V to Min (VIN, 1.22V) + 0.3V Continuous Power Dissipation (TA = +70NC) TSSOP (derate 25.6mW/NC above +70NC)........ ….2051.3mW Operating Temperature Range........................... -40NC to +85NC Junction Temperature.........................................………..+150NC Storage Temperature Range............................. -65NC to +150NC Lead Temperature (soldering, 10s).................. …………+300NC Soldering Temperature (reflow)........................ …………+260NC Note 1: DC current is also limited by the thermal design of the system. PACKAGE THERMAL CHARACTERISTICS (Note 2) TSSOP Junction-to-Ambient Thermal Resistance (BJA)............ +39NC/W Junction-to-Case Thermal Resistance (BJC)................... +3NC/W Note 2:Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. 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 (VIN = 4.5V to 36V, TA = -40NC to +85NC, unless otherwise noted. Typical values are at VIN = 24V, RISET = 12kI, TA = +25°C.) (Note 3) PARAMETER IN Voltage Range Shutdown Input Current Shutdown Output Current Reverse Input Current Supply Current SYMBOL VIN ISHDN IOFF IIN_RVS IIN Internal Overvoltage Trip Level VOVLO Internal Undervoltage Trip Level VUVLO Overvoltage-Lockout Hysteresis External OVLO Leakage Current 4.5 VOUT = 0V VIN = -40V, VOUT = VGND = 0V VIN rising External UVLO Leakage Current BG Reference Voltage 2 32 VIN falling FA 2 FA FA 490 700 33 34 32 17.5 18.5 19.5 18.2 19.2 20.2 VOVLOSEL VBG V 15 VIN rising VOVLO < 1.2V (Note 5) (Note 5) UNITS 36 VIN falling (Note 4) IUVLO_LEAK MAX -35 VIN = 15V, RISET = 12kI VOVLOSEL IOVLO_LEAK TYP VEN = 0V, VHVEN = 5V External UVLO Adjustment Range External UVLO Select Voltage MIN % of typical OVLO External OVLO Adjustment Range External OVLO Select Voltage CONDITIONS 3 FA V V % 6 36 V 0.3 0.50 V -100 +100 nA 4.5 24 V 0.3 0.50 V +100 nA 1.234 V -100 1.186 1.210 Maxim Integrated MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy ELECTRICAL CHARACTERISTICS (continued) (VIN = 4.5V to 36V, TA = -40NC to +85NC, unless otherwise noted. Typical values are at VIN = 24V, RISET. = 12kI, TA = +25°C.) (Note 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 100 INTERNAL FETs Internal FET On-Resistance RON ILOAD = 100mA, VIN R 8V Current-Limit Adjustment Range ILIM (Notes 5, 6) Current-Limit Accuracy FLAG Assertion Drop Voltage Threshold VFA Increase (VIN - VOUT) drop until FLAG asserts, VIN = 24V Reverse Current Blocking Threshold VRIB VOUT - VIN Reverse Blocking Leakage Current IRBL VOUT - VIN > 160mV, current into OUT 160 mI 0.7 4.2 A -15 +15 % 560 40 mV 100 160 mV 400 600 FA FLAG OUTPUT FLAG Output Logic-Low Voltage ISINK = 1mA FLAG Output Leakage Current VIN = VFLAG = 5V, FLAG desasserted 0.4 V 2 FA 3.5 V LOGIC INPUT HVEN Threshold Voltage 1 VHVEN_TH 2 HVEN Threshold Hysteresis HVEN Input Leakage Current IHVEN_LEAK HVEN Input Reverse Leakage Current IHVEN_RLEAK VIN = VHVEN = -36V EN, RIEN Input Logic-High VIH EN, RIEN Input Logic-Low VIL EN, RIEN Input Leakage Current 2 IEN_LEAK, IRIEN_LEAK 26 VHVEN = 36V -45 % 40 -27 FA 1.4 VEN = VRIEN = 5.0V FA V -1 0.4 V +1 FA THERMAL PROTECTION Thermal Shutdown TJC_MAX Low-to-high temperature 150 NC Thermal-Shutdown Hysteresis TJC_HYST High-to-low temperature 30 NC TIMING CHARACTERISTICS (Note 7) Switch Turn-On Time tON From OFF to IN, see Table 1. RLOAD = 240I, COUT = 470FF 25 ms Switch Turn-Off Time tOFF RLOAD = 47I 3 Fs Overvoltage Switch Turn-Off Time tOFF_OVP VIN > VOVLO to VOUT = 80% of VOVLO, RLOAD = 47I, RSETI = 10kI 3 Fs Overcurrent Switch Turn-Off Time tOFF_OCP IIN > ILIM, after tBLANK, ILIM = 1A 3 Fs IN Debounce Time tDEB Blanking Time tBLANK Autoretry Time tRETRY Maxim Integrated VIN changes from 0V to greater than VUVLO to VOUT = 10% of VIN After blanking time from IOUT > ILIM to FLAG clear (deassertion) (Note 8) 15.0 16.7 18.4 ms 18.6 20.7 22.8 ms 540 600 660 ms 3 MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy ELECTRICAL CHARACTERISTICS (continued) (VIN = 4.5V to 36V, TA = -40NC to +85NC, unless otherwise noted. Typical values are at VIN = 24V, RISET. = 12kI, TA = +25°C.) (Note 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS ESD PROTECTION Human Body Model, IN bypassed to GND with a 1FF low-ESR ceramic capacitor IN Q15 kV Note 3: All units are 100% production tested at TA = +25NC. Limits over the operating temperature range are guaranteed by design and characterization; not production tested. Note 4: Not production tested, user settable. See overvoltage/undervoltage lockout instructions. Note 5: Guaranteed by design; not production tested. UVLO and OVLO are internally clamped to BG reference voltage. Note 6: The current limit can be set below 700mA with a decreased accuracy. Note 7: All timing is measured using 20% and 80% levels. Note 8: The ratio between the autoretry time and blanking time is fixed and equal to 30. Timing Diagrams AUTORETRY VERSIONS tBLANK tRETRY tBLANK tRETRY tBLANK tBLANK tRETRY OUT THE DEVICE COMES OUT OF THERMAL SHUTDOWN MODE CURRENT LIMIT LOAD CURRENT THE DEVICE GOES TO THERMAL SHUTDOWN MODE FLAG NOTE: TIME NOT IN SCALE Figure 1. Autoretry Fault Diagram 4 Maxim Integrated MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy Timing Diagrams (continued) LATCH VERSION tBLANK tBLANK OUT CURRENT LIMIT LOAD CURRENT THE DEVICE GOES TO THERMAL SHUTDOWN MODE THE DEVICE COMES OUT OF THERMAL SHUTDOWN MODE INPUT OR EN CYCLE FLAG NOTE: TIME NOT IN SCALE Figure 2. Latch-Off Fault Diagram CONTINUOUS VERSIONS tBLANK OUT THE DEVICE COMES OUT OF THERMAL SHUTDOWN MODE CURRENT LIMIT LOAD CURRENT THE DEVICE GOES TO THERMAL SHUTDOWN MODE FLAG NOTE: TIME NOT IN SCALE Figure 3. Continuous Fault Diagram Maxim Integrated 5 MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy Timing Diagrams (continued) < tDEB < tDEB tDEB UVLO THRESHOLD VIN ON OFF SWITCH STATUS NOTE: TIME NOT IN SCALE Figure 4. Debounce Timing Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) IN SUPPLY CURRENT vs. SUPPLY VOLTAGE TA = +85°C 0.5 0.4 0.3 TA = +25°C 0.2 0.7 0.6 0.5 0.4 0.3 0.2 TA = -40°C 0.1 0.1 0 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 6 35 40 MAX14571 toc03 0.8 1.3 NORMALIZED ON-RESISTANCE 0.7 SETI UNCONNECTED 0.9 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 0.8 MAX14571 toc02 SETI UNCONNECTED 0.6 1.0 MAX14571 toc01 1.0 0.9 NORMALIZED ON-RESISTANCE vs. SUPPLY VOLTAGE IN SUPPLY CURRENT vs. TEMPERATURE 1.2 TA = +85°C 1.1 TA = +25°C 1.0 0.9 TA = -40°C 0.8 VIN = +24V -40 -15 10 35 TEMPERATURE (°C) 60 IOUT = 100mA 0.7 85 12 15 18 21 24 SUPPLY VOLTAGE (V) Maxim Integrated MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) 1.1 1.0 0.9 0.8 0.7 0.6 -15 10 35 60 1.00 0.98 0.96 0.94 85 8 MAX14571 toc06 1.04 1.02 1.00 0.98 0.96 0.94 0.92 RSETI = 17.4kI 5 1.06 VIN = +24V 0.90 11 14 17 20 23 26 29 32 35 -40 -15 10 35 60 TEMPERATURE (°C) NORMALIZED OVLO THRESHOLD vs. TEMPERATURE NORMALIZED UVLO THRESHOLD vs. TEMPERATURE SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE 1.02 1.00 0.98 0.96 0.94 0.92 -15 10 35 60 1.04 1.02 1.00 0.98 0.96 0.94 0.92 VIN = +24V 0.90 1.06 VIN = +24V 0.90 85 25 -40 -15 10 35 60 20 15 10 VIN = +24V EN = LOW HVEN = 100kI PULLUP TO VIN OUT = OVLO = UVLO = GND 5 0 -40 85 -15 10 35 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) SHUTDOWN REVERSE CURRENT vs. TEMPERATURE TURN-ON TIME vs. TEMPERATURE TURN-OFF TIME vs. TEMPERATURE 25 20 15 VIN = -24V EN = LOW HVEN = 100kI PULLUP TO VIN OUT = OVLO = UVLO = GND 10 5 14 12 10 8 6 -15 10 35 TEMPERATURE (°C) Maxim Integrated 60 85 90 80 70 60 50 40 30 4 20 2 10 EN TRANSITION TO 10% OF VIN 0 0 -40 -15 10 35 TEMPERATURE (°C) 60 85 85 MAX14571 toc12 16 TURN-OFF TIME (µs) 30 18 60 100 MAX14571 toc11 20 MAX14571 toc10 35 85 MAX14571 toc09 1.08 SHUTDOWN SUPPLY CURRENT (µA) 1.04 1.10 MAX14571 toc08 MAX14571 toc07 1.06 -40 1.08 SUPPLY VOLTAGE (V) 1.08 NORMALIZED OVLO THRESHOLD 1.02 1.10 TEMPERATURE (°C) 1.10 -40 1.04 0.90 NORMALIZED UVLO THRESHOLD -40 1.06 0.92 VIN = +24V 0.5 SHUTDOWN SUPPLY CURRENT (µA) 1.08 NORMALIZED CURRENT LI MIT 1.2 MAX14571 toc05 1.3 1.10 TURN-ON TIME (ms) NORMALIZED ON-RESISTANCE 1.4 NORMALIZED CURRENT LI MIT MAX14571 toc04 1.5 NORMALIZED CURENT LIMIT vs. TEMPERATURE NORMALIZED CURRENT LIMIT vs. SUPPLY VOLTAGE NORMALIZED ON-RESISTANCE vs. TEMPERATURE EN TRANSITION TO 90% OF VOUT COUT = 10µF RLOAD = 480I 0 -40 -15 10 35 60 85 TEMPERATURE (°C) 7 MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy Pin Configuration TOP VIEW IN 1 IN 2 IN 3 UVLO 4 OVLO 5 SETI 6 GND 7 + 14 OUT 13 OUT 12 OUT MAX14571 MAX14572 MAX14573 11 FLAG 10 EN *EP 9 RIEN 8 HVEN TSSOP *CONNECT EXPOSED PAD TO GND Pin Description PIN NAME 1, 2, 3 IN 4 UVLO Externally Programmable Undervoltage-Lockout Threshold. Connect UVLO to GND to use the default internal UVLO threshold. Connect UVLO to an external resistor-divider to define a threshold externally and override the preset internal UVLO threshold. 5 OVLO Externally Programmable Overvoltage-Lockout Threshold. Connect OVLO to GND to use the default internal OVLO threshold. Connect OVLO to an external resistor-divider to define a threshold externally and override the preset internal OVLO threshold. 6 SETI Overload Current-Limit Adjust. Connect a resistor from SETI to GND to program the overcurrent limit. If SETI is unconnected, the current limit is set to 0A. If SETI is connected to GND, the FETs turn off and FLAG is asserted. Do not connect more than 10pF to SETI. 7 GND Ground 8 HVEN Active-Low Enable Input. HVEN is a high-voltage-capable enable input. Drive HVEN low for normal operation. Drive HVEN high to disable the device. HVEN has up to 36V overvoltage protection at the input (Table 1). 9 RIEN Reverse-Current Enable Input. Connect RIEN to GND to disable the reverse-current flow protection. Connect RIEN to logic-high to activate the reverse-current flow protection. 10 EN 11 FLAG Open-Drain, Fault Indicator Output. FLAG goes low when the fault duration exceeds the blanking time, reverse current is detected, thermal-shutdown mode is active, OVLO threshold is reached, or SETI is connected to GND. 12, 13, 14 OUT Output Voltage. Output of internal FETs. Bypass OUT to GND with a 1FF ceramic capacitor placed as close as possible to the device. For a long output cable or inductive lead, see the Applications Information section. — EP 8 FUNCTION Overvoltage-Protection Input. Bypass IN to GND with a 1FF ceramic capacitor placed as close as possible to the device. Use a 1FF, low-ESR ceramic capacitor to enable Q15kV (HBM) ESD protection on IN. For hot-plug applications, see the Applications Information section. Active-High Enable Input. Drive EN high for normal operation. Drive EN low to disable the device (Table 1). Exposed Pad. Internally connected to GND. Connect EP to a large ground plane to maximize thermal performance. Do not use EP as the single GND connection. Maxim Integrated MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy Functional Diagram MAX14571 MAX14572 MAX14573 IN OUT OUT IN OUT REVERSE-INPUT REVERSE-CURRENT PROTECTION IN RIEN FLAG N CONTROL LOGIC VBG EN UVLO HVEN VSEL THERMAL SHUTDOWN OVLO VSEL SETI Maxim Integrated GND 9 MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy Detailed Description The MAX14571/MAX14572/MAX14573 are adjustable overvoltage- and overcurrent-protection devices designed to protect systems against positive and negative input voltage faults up to Q40V, and feature low 100mI (typ) on-resistance FETs. If the input voltage exceeds the OVLO threshold or falls below the UVLO, the internal FETs are turned off to prevent damage to the protected components. If the OVLO or the UVLO pin is set below the external OVLO or UVLO select thresholds (VOVLOSEL and VUVLOSEL), the device automatically selects the internal Q3% (typ) accurate trip thresholds. The internal OVLO threshold is preset to 33V (typ), and the internal UVLO threshold is preset to 19.2V (typ). t BLANK ILOAD = ILIM t t + BLANK RETRY With a 20.7ms (typ) tBLANK and 600ms (typ) tRETRY, the duty cycle is 3.3%, resulting in a 96.7% power savings. Latch-Off (MAX14572) Programmable Current Limit/Threshold When the current threshold is reached, the tBLANK timer begins counting. The FLAG asserts if the overcurrent condition is present for tBLANK. The timer resets when the overcurrent condition disappears before tBLANK has elapsed. The switch turns off and stays off if the overcurrent condition continues beyond the blanking time. To reset the switch, either toggle the control logic EN or HVEN or cycle the input voltage. If the die temperature exceeds +150NC (typ) due to self-heating, the MAX14572 latches off (Figure 2.) Autoretry (MAX14571) When the current threshold is reached, the MAX14573 limits the output current to the programmed current limit. The FLAG asserts if the overcurrent condition is present for tBLANK and deasserts when the overload condition is removed. If the die temperature exceeds +150NC (typ) due to self-heating, the MAX14573 enables thermal shutdown until the die temperature drops by approximately 30NC (Figure 3). The ICs feature programmable current-limit protection up to 4.2A. Once current reaches the threshold, the MAX14571 turns off after 20.7ms (typ) blanking time and stays off during the retry period. The MAX14572 latches off after the blanking time, and the MAX14573 limits the current continuously. A resistor from SETI to GND sets the current limit/threshold for the switch (see the Setting the Current Limit/ Threshold section). If the output current is limited at the current threshold value for a time equal to or longer than tBLANK, the output FLAG asserts and the MAX14571 enters the autoretry mode, the MAX14572 latches off the switch, and the MAX14573 enters the continuous current-limit mode. When the current threshold is reached, the tBLANK timer begins counting. The FLAG asserts if the overcurrent condition is present for tBLANK. The timer resets if the overcurrent condition disappears before tBLANK has elapsed. A retry time delay, tRETRY, is started immediately after tBLANK has elapsed and during tRETRY time, the FETs are off. At the end of tRETRY, the FETs are turned on again. If the fault still exists, the cycle is repeated and the FLAG stays low. When the fault is removed, the FETs stay on. If the die temperature exceeds +150NC (typ) due to self-heating, the MAX14571 enables thermal shutdown until the die temperature drops by approximately 30NC (Figure 1). The autoretry feature reduces the system power in case of overcurrent or short-circuit conditions. During tBLANK time, when the switch is on, the supply current is held 10 at the current limit. During tRETRY time, when the switch is off, there is no current through the switch. Thus, the output current is much less than the programmed current limit. Calculate the average output current using the following equation: Continuous Current Limit (MAX14573) Reverse-Current Enable (RIEN) This feature disables the reverse-current protection and enables reverse-current flow from OUT to IN. The reverse-current enable feature is useful in applications with inductive loads. Fault Flag Output FLAG is an open-drain fault indicator output and requires an external pullup resistor to a DC supply. FLAG goes low when any of the following conditions occur: • The blanking time has elapsed. • The reverse-current protection has tripped. • The die temperature exceeds +150NC. • SETI is connected to ground. • OVLO threshold is reached. Maxim Integrated MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy Thermal-Shutdown Protection The devices have a thermal-shutdown feature to protect them from overheating. The devices turn off and the FLAG asserts when the junction temperature exceeds +150NC (typ). The devices exit thermal shutdown and resume normal operation after the junction temperature cools by 30NC (typ), except for the MAX14572, which remains latched off. The thermal limit behaves similarly to the current limit. For the MAX14571 (autoretry), the thermal limit works with the autoretry timer. When the device comes out of the thermal limit, it starts after the retry time. For the MAX14572 (latch off), the device latches off until power or EN cycle. For the MAX14573 (continuous), the device only disables while the temperature is over the limit. There is no blanking time for thermal protection. Input Debounce Protection The ICs feature input debounce protection. When the input voltage is higher than the UVLO threshold voltage for a period greater than the debounce time (tDEB), the internal FETs are turned on. This feature is intended for applications where the EN or HVEN signal is present when the power supply ramps up (Figure 4). Applications Information Setting the Current Limit/Threshold A resistor from SETI to ground programs the current limit/ threshold value for the devices. Leaving SETI unconnected selects a 0A current limit/threshold. Connecting SETI to ground asserts FLAG. Use the following formula to calculate the current limit: 11500 R SETI (kΩ) = ILIM (mA) Overvoltage Lockout (OVLO) The devices have a 33V (typ) preset OVLO threshold when the voltage at OVLO is set below the external OVLO select voltage (VOVLOSEL). Connect OVLO to GND to activate the preset OVLO threshold. Connect the external resistors to the OVLO pin as shown in the Typical Operating Circuit to externally adjust the OVLO threshold. Use the following equation to adjust the OVLO threshold. The recommended value for R3 is 2.2MI: R3 VOVLO= VBG × 1 + R4 Undervoltage Lockout (UVLO) The devices have a 19.2V (typ) preset UVLO threshold when the voltage at UVLO is set below the external UVLO select voltage (VUVLOSEL). Connect UVLO to GND to activate the preset UVLO threshold. Connect the external resistors to the UVLO pin as shown in the Typical Operating Circuit to externally adjust the UVLO threshold. Use the following equation to adjust the UVLO threshold. The recommended value for R1 is 2.2MI: R1 VUVLO= VBG × 1 + R2 Switch Control There are two independent enable inputs (HVEN and EN) for the devices. HVEN is a high-voltage-capable input. Toggle HVEN or EN to reset the fault condition once a short circuit is detected and the devices shut down (Table 1). Maxim Integrated IN Bypass Capacitor Connect a minimum of 1FF capacitor from IN to GND to limit the input voltage drop during momentary output short-circuit conditions. Larger capacitor values further reduce the voltage undershoot at the input. Hot-Plug IN In many system powering applications, an input-filtering capacitor is required to lower the radiated emission, enhance the ESD capability, etc. In hot-plug applications, parasitic cable inductance, along with the input capacitor, cause overshoot and ringing when the powered cable is connected to the input terminal. This effect causes the protection device to see almost twice the applied voltage. An input voltage of 24V can easily exceed the absolute maximum rating of 40V, which may permanently damage the device. A transient voltage suppressor (TVS) is often used for industrial applications to protect the system from these conditions. We recommend using a TVS that is capable of limiting surge to 40V placed close to the input terminal. Table 1. Switch Control HVEN 0 EN SWITCH STATUS 0 On 1 0 Off 0 1 On 1 1 On 11 MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy OUT Bypass Capacitor For stable operation over the full temperature range and over the entire programmable current-limit range, connect a 1FF ceramic capacitor from OUT to ground. Excessive output capacitance can cause a false overcurrent condition due to decreased dV/dt across the capacitor. Calculate the maximum capacitive load (CMAX) value that can be connected to OUT by using the following formula: C MAX (µF) = ILIM (mA) x t BLANK(MIN) (ms) VIN (V) For example, for VIN = 24V, tBLANK = 15ms, and ILIM = 4.2A, CMAX equals 2625FF. Output Freewheeling Diode for Inductive Hard Short to Ground In applications that require protection form a sudden short to ground with an inductive load or long cable, a Schottky diode between the OUT terminal and ground is recommended. This is to prevent a negative spike on OUT due to the inductive kickback during a short-circuit event. traces to the power bus. During normal operation, the power dissipation is small and the package temperature change is minimal. If the output is continuously shorted to ground at the maximum supply voltage, the switches with the autoretry option do not cause thermal-shutdown detection to trip: P(MAX) = VIN(MAX) × IOUT(MAX) × t BLANK t RETRY + t BLANK Attention must be given to the MAX14573 continuous current-limit version when the power dissipation during a fault condition can cause the device to reach the thermal-shutdown threshold. Thermal vias from the exposed pad to ground plane are highly recommended to increase the system thermal capacitance while reducing the thermal resistance to the ambient. ESD Test Conditions The devices are specified for Q15kV (HBM) typical ESD resistance on IN when IN is bypassed to ground with a 1FF low-ESR ceramic capacitor. No capacitor is required for Q2kV (HBM) typical ESD on IN. All the pins have a Q2kV (HBM) typical ESD protection. Layout and Thermal Dissipation To optimize the switch response time to output shortcircuit conditions, it is very important to keep all traces as short as possible to reduce the effect of undesirable parasitic inductance. Place input and output capacitors as close as possible to the device (no more than 5mm). IN and OUT must be connected with wide short RC 1MI CHARGE-CURRENTLIMIT RESISTOR RD 1.5kI HBM ESD Protection Figure 5a shows the Human Body Model, and Figure 5b shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the device through a 1.5kI resistor. IP 100% 90% DISCHARGE RESISTANCE IR PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) AMPERES HIGHVOLTAGE DC SOURCE Cs 100pF STORAGE CAPACITOR DEVICE UNDER TEST 36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM Figure 5a. Human Body ESD Test Model 12 Figure 5b. Human Body Current Waveform Maxim Integrated MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy Chip Information PROCESS: BiCMOS Maxim Integrated Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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 OUTLINE NO. LAND PATTERN NO. 14 TSSOP-EP U14E+3 21-0108 90-0119 13 MAX14571/MAX14572/MAX14573 Adjustable Overvoltage and Overcurrent Protectors with High Accuracy Revision History REVISION NUMBER REVISION DATE 0 9/12 Initial release 1 12/12 Removed future product asterisk and notes for the MAX14571/MAX14573, style edits. DESCRIPTION PAGES CHANGED — 1–6, 8, 10, 11, 14 Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. 14 © 2012 Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 Maxim Integrated Products, Inc. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.