19-4137; Rev 0; 5/08 Overvoltage Protector with Active Current Limit The MAX4978–MAX4981 overvoltage-protection devices protect low-voltage systems against voltage faults up to +28V and feature a low 85mΩ RON FET, an active current limiter, and lithium-ion battery overcharge protection (MAX4980/MAX4981). These devices are used to protect the charger input port on a portable device. The overvoltage protector feature protects against voltages up to 28V with two different trip thresholds: 5.7V (MAX4978/MAX4980/MAX4981) and 6.8V (MAX4979). There is an undervoltage protector with two different trip thresholds: 4.4V (MAX4978) and 2.63V (MAX4979/ MAX4980/MAX4981). The overcurrent limiter and battery voltage monitor features provide a second layer of protection for a lithiumion battery charger. The overcurrent limiter is available in two different thresholds: 0.9A (MAX4978/MAX4979/ MAX4980) and 1.95A (MAX4981). Once current reaches the threshold, it is held for a 20ms blanking time. If the current is still at the limit after the blanking time, the FET is turned off, and the device restarts the cycle after 160ms. The battery voltage monitor measures the voltage of a lithium-ion battery and disables the FET if the battery voltage reaches 4.4V (MAX4980/MAX4981). Features ♦ Input Voltage Protection Up to +28V ♦ Integrated nFET Switch, 85mΩ (typ) ♦ Preset Overvoltage Protection Trip Level 5.7V (typ) (MAX4978/MAX4980/MAX4981) 6.8V (typ) (MAX4979) ♦ Low-Current Undervoltage Lockout Mode ♦ Overcurrent Protection ♦ Internal 160ms (typ) Startup Delay ♦ Thermal-Shutdown Protection ♦ Battery Overcharge Protection (MAX4980/MAX4981) ♦ Startup Debounce Time Indicator (MAX4978/MAX4979) ♦ Small, 8-Pin (2mm x 3mm) TDFN Package Pin Configuration TOP VIEW OUT I.C. I.C. GND 8 7 6 5 The MAX4978–MAX4981 are available in a small 8-pin TDFN (2mm x 3mm) package and are specified over the extended -40°C to +85°C temperature range. MAX4978 MAX4979 MAX4980 MAX4981 Applications Cell Phones MP3 Players Digital Still Cameras PDAs and Palmtop Devices *EP 1 2 3 IN SDT(BAT) I.C. 4 EN TDFN-EP (BAT) IS FOR MAX4980/MAX4981 ONLY. *EP = EXPOSED PAD. CONNECT EP TO GND. Typical Application Circuit appears at end of data sheet. Ordering Information/Selector Guide PART PIN-PACKAGE CURRENT LIMIT (mA) BATTERY MONITOR UVLO (V) OVLO (V) TOP MARK PKG CODE MAX4978ETA+ 8 TDFN-EP* 900 No 4.4 5.7 AAK T823-1 MAX4979ETA+** 8 TDFN-EP* 900 No 2.63 6.8 AAL T823-1 MAX4980ETA+ 8 TDFN-EP* 900 Yes 2.63 5.7 AAM T823-1 MAX4981ETA+ 8 TDFN-EP* 1950 Yes 2.63 5.7 AAN T823-1 Note: All devices specified over the -40°C to +85°C operating temperature range. +Denotes a lead-free package. *EP = Exposed pad. **Future product—contact factory for availability. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX4978–MAX4981 General Description MAX4978–MAX4981 Overvoltage Protector with Active Current Limit ABSOLUTE MAXIMUM RATINGS (Voltages referenced to GND.) IN, SDT ................................................................. -0.3V to +30V OUT ........................................................................... -0.3V to IN EN, BAT .................................................................. -0.3V to +6V SDT Continuous Current ................................................. ±50mA Continuous Power Dissipation (TA = +70°C) 8-Pin 2mm x 3mm TDFN (derate 16.7mW/°C above +70°C) ........................................................... 1333mW Junction-to-Case Thermal Resistance (θJC) (Note 1) 8-Pin 2mm x 3mm TDFN ......................................... 10.8°C/W Junction-to-Ambient Thermal Resistance (θJA) (Note 1) 8-Pin 2mm x 3mm TDFN ............................................ 60°C/W 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 Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a 4-layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.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 = 5.0V, VEN = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS TYP MAX 28 V IOUT < ILIM_MIN 130 190 µA 35 60 µA 15 23 µA 4.4 4.5 2.63 2.70 Input Voltage Range VIN Input Supply Current IIN UVLO Supply Current IUVLO VIN = 2.3V Shutdown Supply Current ISHDN V EN = 5V 2.3 MAX4978 IN Undervoltage Lockout VUVLO MIN MAX4979/MAX4980/ MAX4981 VIN falling 4.2 VIN rising 4.3 VIN falling 2.5 VIN rising 2.56 IN Undervoltage Lockout Hysteresis 1 MAX4978/MAX4980/ MAX4981 IN Overvoltage Lockout VOVLO MAX4979 VIN falling 5.5 VIN rising 5.6 VIN falling 6.5 VIN rising 6.65 IN Overvoltage Lockout Hysteresis BAT Overvoltage Trip Level VBOTL BAT Input Leakage Current Switch On-Resistance MAX4980/MAX4981, VBAT rising ILKGB RON 2 5.8 6.80 6.95 ILIM TSHDN 4.4 TA rising TA=+25°C 850 TA= 0°C to +85°C 800 V % 4.5 1 IOUT = 100mA MAX4981 Thermal Shutdown 5.7 MAX4980/MAX4981, VBAT = 4.2V MAX4978, MAX4979, MAX4980 Overcurrent Protection Threshold 4.3 MAX4980/MAX4981 V % 1 BAT Overvoltage Hysteresis UNITS V % 1 µA 85 160 mΩ 900 950 1000 TA= -40°C to +0°C 780 TA=+25°C 1850 1950 2050 TA= -40°C to +85°C 1750 1950 2150 1000 160 _______________________________________________________________________________________ mA °C Overvoltage Protector with Active Current Limit (VIN = 5.0V, VEN = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN Thermal-Shutdown Hysteresis EN Input High Voltage EN Input Low Voltage TYP MAX UNITS 10 VIH °C 1.5 V 0.6 V +1 µA MAX4978/MAX4979, ISINK = 20mA 1 V ILKGS MAX4978/MAX4979, V SDT = 28V, SDT deasserted 1 µA IN Debounce Time tDEB VUVLO < VIN < VOVLO to charge-pump enable, Figure 1 200 ms Switch Turn-On Time tON Time from VOUT = 10% of VIN to VOUT = 90% of VIN, RL = 10Ω, CL = 10µF Switch Turn-Off Time tOFF VIN < VUVLO or VIN > VOVLO to internal switch off, RL = 1kΩ EN Input Leakage Current SDT Output Low Voltage SDT Leakage Current VIL ILKGE VOL V EN = 5.5V or 0V -1 DYNAMIC (Note 3) Current-Limit Blanking Time tBLANK Short circuit applied, Figure 1 Current-Limit Reaction Time tREAC Short circuit applied Overcurrent Autoretry Time tRETRY Figure 1 120 160 1.5 15 ms 5 15 µs 20 25 ms 5 120 160 µs 200 ms Note 2: All devices are 100% production tested at TA = +25°C. Specifications over -40°C to +85°C are guaranteed by design. Note 3: All timing is measured using 10% and 90% levels, unless otherwise noted. _______________________________________________________________________________________ 3 MAX4978–MAX4981 ELECTRICAL CHARACTERISTICS (continued) MAX4978–MAX4981 Overvoltage Protector with Active Current Limit Timing Diagram tDEB tDEB tBLANK tRETRY tBLANK tRETRY OVLO IN UVLO OUT CURRENT LIMIT LOAD CURRENT SDT Figure 1. Timing Diagram 4 _______________________________________________________________________________________ tBLANK Overvoltage Protector with Active Current Limit NORMALIZED ON-RESISTANCE vs. TEMPERATURE IIN (μA) 80 60 MAX4978 40 1.1 1.0 0.9 0.8 20 0.7 0 2 7 17 12 22 -15 1.000 0.995 0.990 60 85 -15 10 35 60 35 1.05 1.00 0.95 0.90 -40 -15 10 35 60 -40 85 -15 10 35 85 OVERVOLTAGE FAULT RESPONSE POWER-UP RESPONSE MAX4978-81 toc07 1.004 60 TEMPERATURE (°C) MAX4978-81 toc09 MAX4978-81 toc08 1.006 85 1.10 TEMPERATURE (°C) 1.008 60 NORMALIZED CURRENT LIMIT vs. TEMPERATURE 4.35 NORMALIZED STARTUP DELAY/AUTORETRY/ BLANKING TIME vs. TEMPERATURE 10 BATTERY OVERVOLTAGE THRESHOLD vs. TEMPERATURE 4.40 TEMPERATURE (°C) -15 TEMPERATURE (°C) 4.45 85 MAX4978-81 toc03 -40 4.30 -40 NORMALIZED STARTUP DELAY/AUTORETRY/BLANKING TIME 35 MMAX4978-81 toc05 1.005 10 4.50 BATTERY OVERVOLTAGE THRESHOLD MAX4978-81 toc04 NORMALIZED OVLO THRESHOLD 1.010 0.995 TEMPERATURE (°C) VIN (V) NORMALIZED OVLO THRESHOLD vs. TEMPERATURE 1.000 0.990 -40 27 1.005 MMAX4978-81 toc06 MAX4980/MAX4981 100 1.2 1.010 NORMALIZED CURRENT LIMIT 120 MAX4978-81 toc02 140 1.3 NORMALIZED ON-RESISTANCE MAX4978-81 toc01 160 NORMALIZED UVLO THRESHOLD vs. TEMPERATURE NORMALIZED UVLO THRESHOLD SUPPLY CURRENT vs. SUPPLY VOLTAGE RL = 1kΩ VIN VIN 5V/div 2V/div 1.002 VOUT 1.000 VOUT 5V/div 0.998 VSDT 0.996 2V/div 5V/div 0.994 0.992 -40 -15 10 35 60 85 40ms/div 4μs/div TEMPERATURE (°C) _______________________________________________________________________________________ 5 MAX4978–MAX4981 Typical Operating Characteristics (VIN = 5.0V, EN = GND, TA = +25°C, unless otherwise noted.) MAX4978–MAX4981 Overvoltage Protector with Active Current Limit Typical Operating Characteristics (continued) (VIN = 5.0V, EN = GND, TA = +25°C, unless otherwise noted.) UNDERVOLTAGE FAULT RESPONSE SHORT-CIRCUIT RESPONSE BATTERY OVERVOLTAGE FAULT RESPONSE MAX4978-81 toc10 MAX4978-81toc12 MAX4978-81 toc11 RL = 1kΩ 2V/div VIN VBAT VIN 2V/div VOUT 5V/div VSDT VOUT VOUT 5V/div 2V/div 2V/div IOUT 1A/div 4μs/div 100ms/div 2μs/div Pin Description PIN MAX4978/ MAX4979 6 MAX4980/ MAX4981 NAME FUNCTION Supply Voltage Input. IN powers the charge pump required to turn on the internal FET. When the correct adapter is plugged in, a 160ms debounce timer prevents a false turn-on of the internal FET. Bypass IN to GND with a 1µF ceramic capacitor as close to the device as possible to enable ±15kV (HBM) ESD protection. 1 1 IN 2 — SDT Startup Debounce Time Indicator. SDT is an active-low open-drain output that asserts low during the debounce/autoretry time. — 2 BAT Battery Monitor Input. Connect BAT to Li-ion battery terminal. Bypass BAT to GND with a 1µF ceramic capacitor as close to the device as possible to enable ±15kV (HBM) ESD protection. 3, 6, 7 3, 6, 7 I.C. Internally Connected. Connect I.C. to GND. 4 4 EN Active-Low Enable Input. Drive EN low for normal operation. Drive EN high to disable the device. 5 5 GND Ground 8 8 OUT Output Voltage. Output of internal FET. — — EP Exposed Pad. Internally connected to GND. Connect EP to a large ground plane to maximize thermal performance. Do not use EP as the sole GND connection. _______________________________________________________________________________________ Overvoltage Protector with Active Current Limit IN OUT nFET CHARGE PUMP BANDGAP REFERENCE OVLO + CONTROL LOGIC + UVLO EN - MAX4978 MAX4979 SDT GND MAX4980/MAX4981 Functional Diagram OUT IN nFET CHARGE PUMP BANDGAP REFERENCE OVLO + + UVLO - CONTROL LOGIC EN BAT + MAX4980 MAX4981 GND _______________________________________________________________________________________ 7 MAX4978–MAX4981 MAX4978/MAX4979 Functional Diagram MAX4978–MAX4981 Overvoltage Protector with Active Current Limit Detailed Description The MAX4978–MAX4981 family of devices is a combination of an overvoltage protector, overcurrent limiter, and lithium-ion battery overcharge protector (MAX4980/ MAX4981). These devices feature a low 85mΩ (typ) RON FET and are used to protect the charger input port on a portable device. If the input voltage exceeds the overvoltage threshold (OVLO) or falls below the undervoltage threshold (UVLO), the FET is turned off to prevent damage to the protected components. The internal charge pump’s 160ms debounce time prevents false turn-on of the internal FET during startup. SDT is an active-low open-drain output that asserts low during the debounce time after a valid voltage is applied to the input (MAX4978/MAX4979). The MAX4978–MAX4981 feature an overcurrent limiter as a second layer of protection for a lithium-ion battery charger that limits current to a 900mA (MAX4978/ MAX4979/MAX4980) or 1950mA (MAX4981) threshold for a 20ms blanking time. At the end of the blanking time, if current is still at the threshold, the FET is turned off and the device restarts the cycle after 160ms. The battery voltage monitor measures the voltage of a lithium-ion battery and disables the FET if the battery voltage exceeds 4.4V (MAX4980/MAX4981). Autoretry When the current-limit threshold is reached, the tBLANK timer begins counting. 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 that time, the FET is off. At the end of tRETRY, the FET is turned on again. If the fault still exists, the cycle is repeated. If the fault has been removed, the FET stays on. Battery Overcharge Protector (MAX4980/MAX4981) The MAX4980/MAX4981 feature a battery overcharge protection input (BAT) that triggers a voltage fault, turning off the FET, when VBAT exceeds 4.4V. Startup Debounce Time Indicator (SDT) (MAX4978/MAX4979) SDT is an open-drain output that asserts low during the startup debounce time and during the autoretry time. SDT returns to high impedance once the charge pump turns on. This feature is useful for discharging the AC adapter capacitance during the startup debounce time (Figures 1, 2). Thermal Shutdown Protection The MAX4978–MAX4981 have a thermal-shutdown feature to protect the devices from overheating. The device immediately turns off when the junction temperature exceeds +160°C (typ). These devices exit thermal shutdown after the junction temperature cools by 10°C (typ). EN Input EN is an active-low enable input. Drive EN low for normal operation. Drive EN high to disable the device. Applications Information IN Bypass Capacitor For most applications, bypass IN to GND with a 1µF ceramic capacitor as close to the device as possible to enable ±15kV (HBM) ESD protection on IN. If the power source has significant inductance due to long lead length, take care to prevent overshoots due to the LC tank circuit and provide protection if necessary to prevent exceeding the 30V absolute maximum rating on IN. Undervoltage Lockout (UVLO) BAT Bypass Capacitor The MAX4978 has a 4.4V UVLO threshold, while the MAX4979/MAX4980/MAX4981 have a 2.63V UVLO threshold. When an undervoltage lockout condition occurs with high load current, the voltage at the input to the UVLO comparator may recover due to internal parasitic resistance causing the device to restart. For most applications, bypass BAT to GND with a 1µF ceramic capacitor as close to the device as possible to enable ±15kV (HBM) ESD protection on BAT. If high ESD protection is not necessary, no capacitor is required on BAT. Overvoltage Lockout (OVLO) ESD performance depends on a number of conditions. The MAX4978–MAX4981 are specified for ±15kV (HBM) typical ESD resistance on IN and BAT when IN and BAT are bypassed to ground with a 1µF low ESR ceramic capacitor. Contact Maxim for a reliability report that documents test setup, methodology, and results. The MAX4979 has a 6.8V OVLO threshold, while the MAX4978/MAX4980/MAX4981 have a 5.7V OVLO threshold. 8 ESD Test Conditions _______________________________________________________________________________________ Overvoltage Protector with Active Current Limit ~0.5Ω MAX4978–MAX4981 LONG WIRE RESISTANCE AC-DC CONVERTER CHARGER IN OUT PHONE LOADS nFET 1μF 5V AC ADAPTER CHARGE PUMP BANDGAP REFERENCE OVLO 1kΩ + + UVLO C0NTROL EN CONTROL LOGIC - MAX4978/ MAX4979 SDT GND Figure 2. Typical Application Circuit with SDT RC 1MΩ CHARGE CURRENTLIMIT RESISTOR RD 1.5kΩ 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 Figure 3. Human Body ESD Test Model tRL Figure 4. Human Body Current Waveform Chip Information Human Body Model Figure 3 shows the Human Body Model, and Figure 4 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 that is then discharged into the device through a 1.5kΩ resistor. TIME tDL CURRENT WAVEFORM PROCESS: BiCMOS _______________________________________________________________________________________ 9 Typical Application Circuit CHARGER 5V AC ADAPTER IN OUT PHONE LOADS nFET 1µF CHARGE PUMP BANDGAP REFERENCE OVLO C0NTROL + + UVLO EN CONTROL LOGIC - BAT + MAX4978–MAX4981 Overvoltage Protector with Active Current Limit MAX4980 MAX4981 GND Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 8 TDFN-EP T823-1 21-0174 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. 10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.