19-0923; Rev 1; 2/08 KIT ATION EVALU E L B A AVAIL Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector Features The MAX15009 includes a 300mA LDO regulator, a switched output, and an overvoltage protection (OVP) controller to protect downstream circuits from high-voltage load dump. The MAX15011 includes only the 300mA LDO regulator and switched output. Both devices operate over a wide supply voltage range from 5V to 40V and are able to withstand load-dump transients up to 45V. The MAX15009/MAX15011 feature short-circuit and thermalshutdown protection. These devices offer highly integrated power management solutions for automotive applications such as instrument clusters, climate control, and a variety of automotive power-supply circuits. The 300mA LDO regulator consumes 67µA quiescent current at light loads and is well suited to power always-on circuits during “key off” conditions. The LDO features independent enable and hold inputs, as well as a microprocessor (µP) reset output with adjustable reset timeout period. The switched output of the MAX15009/MAX15011 incorporates a low RDS(ON) (0.28Ω, typ) pass transistor switch internally connected to the output of the LDO regulator. This switch features accurate current-limit sensing circuitry and is capable of controlling remote loads. The MAX15009/MAX15011 feature an adjustable current limit and a programmable delay timer to set the overcurrent detection blanking time of the switch and autoretry timeout. o 300mA LDO Regulator, Switched Output, and OVP Controller (MAX15009) The MAX15009 OVP controller operates with an external enhancement mode n-channel MOSFET. While the monitored voltage remains below the adjustable threshold, the MOSFET stays on. When the monitored voltage exceeds the OVP threshold, the OVP controller quickly turns off the external MOSFET. The OVP controller is configurable as a load-disconnect switch or a voltage limiter. The MAX15009/MAX15011 are available in a thermally enhanced, 32-pin (5mm x 5mm), TQFN package and are fully specified over the -40°C to +125°C automotive operating temperature range. For tape and reel, add a T after “+.” *EP = Exposed pad. o OVP Controller Disconnects or Limits Output Voltage During Battery Overvoltage Conditions o LDO Regulator with Enable, Hold, and Reset Features o Internal 0.28Ω (typ) n-Channel Switch for Switched Output o 100mA Switched Output with Adjustable CurrentLimit Blanking/Autoretry Delay Ordering Information PART PKG CODE MAX15009ATJ+ -40°C to +125°C 32 TQFN-EP* T3255-4 MAX15011ATJ+ -40°C to +125°C 32 TQFN-EP* T3255-4 +Denotes a lead-free package. ILIM OC_DELAY OUT_LDO OUT_LDO IN IN EN_PROT EN_SW Pin Configurations 24 23 22 21 20 19 18 17 TOP VIEW HOLD 25 16 EN_LDO N.C. 26 15 FB_LDO OUT_SW 27 14 N.C. OUT_SW 28 13 SOURCE 12 GATE MAX15009 N.C. 29 N.C. 30 N.C. 31 *EP + *EP = EXPOSED PAD 3 4 5 6 7 8 RESET N.C. 2 PGND Telematics Power Supply 1 SGND N.C. 32 Multimedia Power Supply Typical Operating Circuits and Selector Guide appear at end of data sheet. PINPACKAGE TEMP RANGE N.C. AM/FM Radio Power Supply o 67µA Quiescent Current LDO Regulator N.C. Climate Control o 45V Load Dump Protection N.C. Instrument Clusters o 5V to 40V Wide Operating Supply Voltage Range N.C. Applications o 300mA LDO Regulator and Switched Output (MAX15011) 11 N.C. 10 FB_PROT 9 CT TQFN (5mm x 5mm) Pin Configurations 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. MAX15009/MAX15011 General Description MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector ABSOLUTE MAXIMUM RATINGS (All pins referenced to SGND, unless otherwise noted.) IN, GATE.................................................................-0.3V to +45V EN_LDO, EN_SW, EN_PROT ......................-0.3V to (VIN + 0.3V) SOURCE ......................................................-0.3V to (VIN + 0.3V) OUT_LDO, FB_LDO, FB_PROT, RESET, OC_DELAY .........................................................-0.3V to +12V GATE to SOURCE ..................................................-0.3V to +12V OUT_SW, ILIM, HOLD ......................-0.3V to (VOUT_LDO + 0.3V) OUT_SW to OUT_LDO ...........................................-12V to +0.3V CT to SGND............................................................-0.3V to +12V SGND to PGND .....................................................-0.3V to +0.3V IN, OUT_LDO Current .......................................................700mA OUT_SW Current...............................................................350mA Current Sink/Source (all remaining pins) ............................50mA Continuous Power Dissipation (TA = +70°C) 32-Pin TQFN (derate 34.5mW/°C above +70°C) .............2.7W* Thermal Resistance θJA ..............................................................................29.0°C/W θJC ................................................................................1.7°C/W Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-60°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C *As per JEDEC 51 Standard, Multilayer Board (PCB). 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 = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF, VOUT_LDO = 5V, CT = open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Supply Voltage Range SYMBOL VIN CONDITIONS VIN ≥ VOUT + 1.5V MAX15009 Supply Current IIN MAX15011 Shutdown Supply Current ISHDN IN Undervoltage Lockout VUVLO IN Undervoltage Lockout Hysteresis VUVLO_HYST 2 MIN TYP MAX UNITS 40 V 5 EN_LDO = IN, EN_SW = EN_PROT = 0V, IOUT_LDO = 0µA, LDO on, switch off, protector off, measured from SGND 67 85 EN_LDO = EN_SW = IN, EN_PROT = 0V, LDO ON, IOUT_LDO = 100µA, switch on, IOUT_SW = 0µA, protector off, measured from SGND 290 360 EN_LDO = EN_SW = EN_PROT = IN, LDO ON, IOUT_LDO = 100µA, switch on, IOUT_SW = 0µA, protector on, measured from SGND 360 500 EN_LDO = EN_SW = IN, LDO ON, IOUT_LDO = 100µA, switch on, IOUT_SW = 0µA, measured from SGND 268 360 16 30 EN_LDO = EN_SW = EN_PROT = SGND, measured from SGND µA TA = -40°C to +85°C µA TA = -40°C to +125°C VIN falling, GATE disabled 40 4.10 4.27 4.45 260 _______________________________________________________________________________________ V mV Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector (VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF, VOUT_LDO = 5V, CT = open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Thermal-Shutdown Temperature TSHDN +160 °C Thermal Hysteresis THYST 20 °C LDO Output Voltage VOUT_LDO FB_LDO Set-Point Voltage Dual Mode™ FB_LDO Threshold FB_LDO Input Current VFB_LDO VFB_LDO_TH IFB_LDO LDO Output Voltage VLDO_ADJ LDO Dropout Voltage VDO ILOAD = 1mA, FB_LDO = SGND 4.92 5.00 5.09 ILOAD = 300mA, VIN = 8V, FB_LDO = SGND 4.88 5.00 5.11 With respect to SGND, ILOAD = 1mA, VOUT_LDO = 5V, adjustable output option 1.21 1.235 1.26 FB_LDO rising 0.125 FB_LDO falling 0.064 VFB_LDO = 1V Adjustable output option (Note 2) +100 nA 11.0 V ILOAD = 300mA (Note 3) 800 1500 ILOAD = 200mA (Note 3) 520 1000 (Note 4) 300 LDO Output Current Limit ILIM_LDO OUT_LDO = SGND, VIN = 6V 330 OUT_LDO Load Regulation OUT_LDO Power-Supply Rejection Ratio OUT_LDO Startup Delay Time ΔVOUT/ ΔIOUT PSRR V 1.8 IOUT_LDO OUT_LDO Line Regulation V -100 LDO Output Current ΔVOUT/ ΔVIN V mV mA 500 700 6V ≤ VIN ≤ 40V, ILOAD = 1mA, VOUT_LDO = 5V 0.03 0.2 6V ≤ VIN ≤ 40V, ILOAD = 1mA, FB_LDO = SGND, VOUT_LDO = 3.3V 0.03 0.1 6V ≤ VIN ≤ 40V, ILOAD = 20mA, FB_LDO = SGND, VOUT_LDO = 5V 0.27 1 6V ≤ VIN ≤ 40V, ILOAD = 20mA, VOUT_LDO = 3.3V 0.27 0.5 1mA to 300mA, VIN = 8V, FB_LDO = SGND 0.054 0.15 mA mV/V mV/mA 1mA to 300mA, VIN = 6.3V, VOUT_LDO = 3.3V ILOAD = 10mA, f = 100Hz, 500mVP-P, VOUT_LDO = 5V IOUT_LDO = 0mA, from EN_LDO rising to tSTARTUP_DELAY 10% of VOUT_LDO (nominal), FB_LDO = SGND 0.038 0.100 60 dB 30 µs Dual Mode is a trademark of Maxim Integrated Products, Inc. _______________________________________________________________________________________ 3 MAX15009/MAX15011 ELECTRICAL CHARACTERISTICS (continued) MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector ELECTRICAL CHARACTERISTICS (continued) (VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF, VOUT_LDO = 5V, CT = open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL OUT_LDO Overvoltage Protection Threshold VOV_TH OUT_LDO Overvoltage Protection Sink Current IOV CONDITIONS MIN 1mA sink from OUT_LDO VOUT_LDO = VOUT (nominal) x 1.15 8 TYP MAX UNITS 105 110 %VOUT_LDO 19 mA ENABLE/HOLD INPUTS EN_LDO to EN_PROT Input Threshold Voltage EN_LDO, EN_PROT, EN_SW Input Pulldown Current HOLD Input Threshold Voltage HOLD Input Pullup VIH 2 VIL IEN_PD 0.7 EN_ is internally pulled low to SGND VIH 1 µA 1.4 0.4 VIL IHOLD_PU HOLD is internally pulled high to OUT_LDO V 0.6 V µA RESET RESET Voltage Threshold HIGH RESET Voltage Threshold LOW VOUT_LDO to RESET Delay CT Ramp Current CT Ramp Threshold RESET Output-Voltage Low RESET Open-Drain Leakage Current V R ESET_H VRESET_L tRESET_FALL FB_PROT Input Current 90.0 92.5 95.0 %VOUT_LDO RESET goes HIGH when rising VFB_LDO crosses this threshold 90.0 92.5 95.0 %VFB_LDO RESET goes LOW when falling VOUT_LDO crosses this threshold, FB_LDO = SGND 88 90 92 %VOUT_LDO RESET goes LOW when falling VFB_LDO crosses this threshold 88 90 92 %VFB_LDO VOUT_LDO falling, 0.1V/µs µs VCT = 0V 1.50 2 2.35 µA VCT_TH VCT rising 1.190 1.235 VOL ILEAK_RESET 1.270 V ISINK = 1mA, output asserted 0.1 V Output not asserted 150 nA 1.27 V FB_PROT rising 1.20 VHYST IFB_PROT 1.235 4 VFB_PROT = 1.4V Startup Response Time tSTART EN_PROT rising, EN_LDO = IN, to VGATE = 0.5V GATE Rise Time tGATE GATE rising to +8V, VSOURCE = 0V 4 19 ICT LOAD DUMP PROTECTOR (MAX15009 only) FB_PROT Threshold VTH_PROT Voltage FB_PROT Threshold Hysteresis RESET goes HIGH when rising VOUT_LDO crosses this threshold, FB_LDO = SGND -100 %VTH_PROT +100 nA 20 µs 1 ms _______________________________________________________________________________________ Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector (VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF, VOUT_LDO = 5V, CT = open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER FB_PROT to GATE Turn-Off Propagation Delay GATE Output High Voltage GATE Output Pulldown Current SYMBOL tOV VGATE - VIN IGATEPD GATE Charge-Pump Current IGATE GATE-to-SOURCE Clamp Voltage VCLMP CONDITIONS MIN TYP FB_PROT rising from VTH_PROT 250mV to VTH_PROT + 250mV MAX UNITS 0.6 µs VSOURCE = VIN = 5.5V, RGATE to IN = 1MΩ VIN + 3.2 VIN + 3.5 VIN + 3.8 VSOURCE = VIN; VIN ≥ 14V, RGATE to IN = 1MΩ VIN + 7.0 VIN + 8.1 VIN + 9.5 VGATE = 5V, VEN_PROT = 0V 63 100 GATE = SGND 45 12 V mA µA 16 18 V 36 70 mV SWITCH ΔVSW Switch Dropout Switch Current Limit ISW_LIM Current-Limit Selector ILIM Voltage OC_DELAY Timeout Threshold VILIM ΔVSW = VOUT_LDO - VOUT_SW, IOUT_SW = 100mA, VOUT_LDO = 5V, no external MOSFET ILIM = OUT_LDO, VIN = 8V 170 200 240 RLIM = 100kΩ to SGND, VOUT_LDO = 5V, VIN = 8V 85 100 120 RLIM = 39kΩ to SGND, VOUT_LDO = 5V, VIN = 8V 30 40 50 RLIM = 100kΩ VOC_DELAY OC_DELAY Timeout Pullup Current 0.395 mA V 1.194 1.235 1.270 V IOC_DELAY_UP VOC_DELAY = 0.5V rising 12.5 16.0 21.3 µA OC_DELAY Timeout Pulldown Current IOC_DELAY_DOWN VOC_DELAY = 0.5V, falling 0.75 1.00 1.40 µA Minimum OC_DELAY Timeout tOC_DELAY_MIN EN_SW to OUT_SW Turn-On Time EN_SW to OUT_SW Turn-Off Propagation Delay Note 1: Note 2: Note 3: Note 4: tOV_SW COC_DELAY is unconnected 12 µs OUT_SW rising to +0.5V, ROUT_SW = 1kΩ 38 µs EN_SW falling, VOUT_LDO - VOUT_SW rising to +1V, ROUT_SW = 1kΩ, VOUT_LDO = 5V 18 µs Specifications to -40°C are guaranteed by design and not production tested. 1.8V is the minimum limit for proper HOLD functionality. Dropout is defined as VIN - VOUT_LDO when VOUT_LDO is 98% of the value of VOUT_LDO for VIN = VOUT_LDO + 1.5V. Maximum output current may be limited by the power dissipation of the package. _______________________________________________________________________________________ 5 MAX15009/MAX15011 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND, TA = +25°C, unless otherwise specified.) TA = +25°C 64 62 TA = +85°C 60 58 80 70 60 LOAD CURRENT (mA) LOAD CURRENT (mA) LDO POWER-SUPPLY REJECTION RATIO vs. FREQUENCY VIN UVLO HYSTERESIS vs. TEMPERATURE 350 UVLO HYSTERESIS (mV) LDO PSRR (dB) -20 -30 -40 -50 -60 250 200 100k 5.02 5.00 4.98 4.94 4.92 IOUT_LDO = 10mA 10k 5.06 4.96 150 1k 5.08 5.04 300 -80 100 MAX15009 toc03 LDO LOAD REGULATION -70 -90 10 20 40 60 80 100 120 140 5.10 VOUT_LDO (V) -10 0 TEMPERATURE (°C) 400 MAX15009 toc04 0 0 -60 -40 -20 50 0 25 50 75 100 125 150 175 200 225 250 275 300 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 15 5 TA = +125°C MAX15009 toc05 0 20 10 TA = +85°C 54 52 30 25 TA = -40°C TA = +125°C 56 MAX15009 toc02 TA = +25°C 90 35 ISHDN (μA) GROUND CURRENT (μA) 68 66 100 GROUND CURRENT (μA) TA = -40°C 70 110 MAX15009 toc01 74 72 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE LDO GROUND CURRENT vs. LOAD CURRENT MAX15009 toc06 LDO GROUND CURRENT vs. LOAD CURRENT 1M 100 4.90 -50 -25 0 25 50 75 100 125 150 FREQUENCY (Hz) TEMPERATURE (°C) LDO OUTPUT VOLTAGE vs. INPUT VOLTAGE LDO LOAD-TRANSIENT RESPONSE 0 100 200 MAX15009 toc07 6 IOUT_LDO = 10mA 5 IOUT_LDO = 300mA (PULSED) 4 LDO LOAD-TRANSIENT RESPONSE MAX15009 toc09 IOUT_LDO 100mA/div IOUT_LDO 100mA/div 0A 3 0A 2 VOUT_LDO 5V, AC-COUPLED 100mV/div VOUT_LDO 5V, AC-COUPLED 20mV/div 1 0 0 5 10 15 20 25 30 35 40 2ms/div VIN (V) 6 300 IOUT_LDO (mA) MAX15009 toc08 VOUT_LDO (V) MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector _______________________________________________________________________________________ 400μs/div Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector LDO OUTPUT VOLTAGE vs. TEMPERATURE SWITCH LOAD-TRANSIENT RESPONSE MAX15009 toc10 IOUT_LDO = 100μA 5.05 VOUT_LDO (V) LINE-TRANSIENT RESPONSE MAX15009 toc11 5.10 IOUT_LDO = 10mA MAX15009 toc12 VIN 20V/div IOUT_SW 100mA/div VOUT_LDO 3.3V, AC-COUPLED 50mV/div VOUT_SW 5V, AC-COUPLED 100mV/div 4.95 IOUT_LDO = 100mA 4.90 VOUT_SW 3.3V, AC-COUPLED 50mV/div VOUT_LDO 5V, AC-COUPLED 100mV/div IOUT_LDO = 300mA 4.85 0V 0A 5.00 IOUT_LDO = 100mA IOUT_SW = 100mA VIN = 8V VOUT_PROT 20V/div 0V 4.80 -50 -25 0 25 50 75 100 125 150 400μs/div 40ms/div LDO DROPOUT VOLTAGE vs. LOAD CURRENT SWITCH DROPOUT VOLTAGE vs. LOAD CURRENT TEMPERATURE (°C) MAX15009 toc14 1000 LDO DROPOUT VOLTAGE (mV) 900 0V VOUT_LDO 3.3V, AC-COUPLED 20mV/div VOUT_SW 3.3V, AC-COUPLED 20mV/div VOUT_PROT 10V/div 800 700 600 500 400 300 200 30 25 20 15 10 IOUT_LDO = 10mA 0 0 0 40ms/div 35 5 100 0V 40 MAX15009 toc15 MAX15009 toc13 VIN 10V/div SWITCH DROPOUT VOLTAGE (mV) LINE-TRANSIENT RESPONSE 100 200 0 300 IOUT_LDO (mA) SWITCH DROPOUT VOLTAGE vs. TEMPERATURE 100 STARTUP RESPONSE THROUGH VIN MAX15009 toc17 MAX15009 toc16 60 IOUT_LDO = 10mA SWITCH DROPOUT VOLTAGE (mV) 50 IOUT_SW (mA) 50 VIN 20V/div 0V 40 VRESET 5V/div IOUT_SW = 100mA 30 IOUT_LDO = 100mA IOUT_SW = 70mA EN_LDO = EN_SW = IN 0V VOUT_LDO 5V/div 20 IOUT_SW = 10mA 10 0V VOUT_SW 5V/div 0V 0 -45 -20 5 30 55 80 105 130 20ms/div TEMPERATURE (°C) _______________________________________________________________________________________ 7 MAX15009/MAX15011 Typical Operating Characteristics (continued) (VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND, TA = +25°C, unless otherwise specified.) Typical Operating Characteristics (continued) (VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND, TA = +25°C, unless otherwise specified.) SHUTDOWN RESPONSE THROUGH VIN MAX15008 toc18 14V VEN_LDO 5V/div VIN 10V/div 0V IOUT_LDO = 100mA IOUT_SW = 70mA VEN_LDO = VEN_SW 0V VOUT_SW 5V/div 0V 0V 20ms/div 2ms/div LDO, EN_LDO, AND HOLD TIMING GROUND CURRENT DISTRIBUTION HISTOGRAM (TA = -40°C) MAX15009 toc21 VEN_LDO 5V/div 60 0V HOLD PULLED UP TO OUT_LDO HOLD 5V/div 50 40 30 20 0V 0V VOUT_LDO 5V/div 0V VOUT_SW 5V/div 0V 90 80 70 60 50 40 30 20 10 RESET 5V/div 0V IOUT_LDO = 100mA IOUT_SW = 70mA EN_LDO = EN_SW VRESET 5V/div NUMBER OF PARTS 0V 6V GROUND CURRENT DISTRIBUTION HISTOGRAM (TA = +125°C) 70 NUMBER OF PARTS VOUT_LDO 5V/div 0V VOUT_LDO 5V/div 0V VOUT_SW 5V/div 0V VRESET 5V/div 0V VOUT_LDO 5V/div IOUT_LDO = 100mA IOUT_SW = 70mA EN_LDO = VEN_SW = IN MAX15008 toc20 VIN 20V/div VEN_LDO 5V/div MAX15009 toc22 VRESET 5V/div SHUTDOWN RESPONSE THROUGH EN MAX15008 toc19 MAX15009 toc23 STARTUP RESPONSE THROUGH EN VIN 0V 10 0 0 67 200ms/div 69 71 73 75 79 77 81 51 53 55 57 59 61 63 65 67 69 71 GROUND CURRENT (μA) PROTECTOR GATE VOLTAGE vs. INPUT VOLTAGE (MAX15009 ONLY) GROUND CURRENT (μA) PROTECTOR STARTUP RESPONSE MAX15009 toc25 MAX15009 toc24 50 45 40 GATE VOLTAGE (V) MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector VIN 10V/div 0V VGATE 35 30 VGATE 10V/div 25 20 0V 15 VOUT_PROT 10V/div 10 0V VIN 5 IOUT_PROT = 1A 0 0 5 10 15 20 25 30 35 40 10ms/div VIN (V) 8 _______________________________________________________________________________________ Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009 toc26 MAX15009 toc27 7 6 RESET TIMEOUT DELAY (ms) VIN 20V/div 0V IOUT_PROT = 1A VOV = 25V 0V VGATE 20V/div VGATE 20V/div IOUT_PROT = 1A OV THRESHOLD = 35V 0V 0V 5 4 3 2 VOUT_PROT 20V/div VOUT_PROT 20V/div 1 0V 0V 400μs/div 0 0 40ms/div 2 4 6 8 10 CRESET (nF) RESET TIMEOUT DELAY vs. TEMPERATURE CRESET = 2.2nF 1.4 1.2 1.0 0.8 0.6 0.4 0.2 160 140 120 TA = -40°C 100 TA = +85°C 80 60 TA = +25°C 40 0 20 -50 -25 0 25 50 75 100 125 150 20 40 60 80 100 120 140 160 180 200 TEMPERATURE (°C) ILIM RESISTANCE (kΩ) INTERNAL PRESET SWITCH CURRENT LIMIT vs. TEMPERATURE IOC_DELAY_UP AND IOC_DELAY_DOWN vs. TEMPERATURE MAX15009 toc31 250 240 PRESET CURRENT LIMIT (mA) TA = +125°C 180 CRESET = 220pF MAX15009 toc30 1.6 200 230 220 210 200 190 180 170 160 150 -50 -25 0 25 50 75 TEMPERATURE (°C) 100 125 150 18 16 MAX15009 toc32 RESET TIMEOUT DELAY (ms) 1.8 SWITCH CURRENT LIMIT (mA) MAX15009 toc29 2.0 SWITCH CURRENT LIMIT vs. ILIM RESISTANCE OC_DELAY PULLUP/PULLDOWN CURRENT (μA) VIN 10V/div RESET TIMEOUT DELAY vs. CRESET OVERVOLTAGE LIMIT FAULT MAX15009 toc28 OVERVOLTAGE SWITCH FAULT IOC_DELAY_DOWN 14 12 10 8 6 4 IOC_DELAY_UP 2 0 -50 -25 0 25 50 75 100 125 150 TEMPERATURE (°C) _______________________________________________________________________________________ 9 MAX15009/MAX15011 Typical Operating Characteristics (continued) (VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND, TA = +25°C, unless otherwise specified.) MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector Pin Description PIN NAME FUNCTION MAX15009 MAX15011 1–4, 8, 11, 14, 26, 29–32 N.C. — 1–4, 8, 10–14, 18, 26, 29–32 — N.C. 5 SGND SGND Signal Ground 6 PGND PGND Ground. PGND is also the return path for the overvoltage protector pulldown current for the MAX15009. In this case, connect PGND to SGND at the negative terminal of the bypass capacitor connected to the source of the external MOSFET. For the MAX15011, connect PGND to SGND together to the local ground plane. 7 RESET RESET Active-Low Open-Drain Reset Output. RESET is low while OUT_LDO is below the reset threshold. Once OUT_LDO has exceeded the reset threshold, RESET remains low for the duration of the reset timeout period then goes high. 9 CT CT Reset Timeout Adjust Input. Connect a capacitor (CRESET) from CT to ground to adjust the reset timeout period. See the Setting the RESET Timeout Period section. — Overvoltage-Threshold Adjustment Input. Connect FB_PROT to an external resistive voltage-divider network to adjust the desired overvoltage threshold. Use FB_PROT to monitor a system input or output voltage. See the Setting the Overvoltage Threshold (MAX15009 Only) section. 10 10 No Connection. Not internally connected. FB_PROT 12 GATE — Protector Gate Drive Output. Connect GATE to the gate of an external n-channel MOSFET. GATE is the output of a charge pump with a 45µA pullup current to 8.1V (typ) above IN during normal operation. GATE is quickly turned off through a 63mA internal pulldown during an overvoltage condition. GATE then remains low until FB_PROT has decreased below 96% of the overvoltage threshold. GATE pulls low when EN_PROT is low. 13 SOURCE — Output-Voltage Sense Input. Connect SOURCE to the source of the external n-channel MOSFET. ______________________________________________________________________________________ Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector PIN 15 NAME FUNCTION MAX15009 MAX15011 FB_LDO FB_LDO LDO Voltage Feedback Input. Connect FB_LDO to SGND to select the preset +5V output voltage. Connect FB_LDO to an external resistive voltage-divider for adjustable output operation. See the Setting the Output Voltage section. 16 EN_LDO EN_LDO Active-High LDO Enable Input. Connect EN_LDO to IN or to a logic-high voltage to turn on the regulator. To place the LDO in shutdown, pull EN_LDO low or leave unconnected and leave HOLD unconnected. EN_LDO is internally pulled to SGND through a 1µA current sink. See the Control Logic section. 17 EN_SW EN_SW Active-High Switch Enable Input. Connect EN_SW to IN or to a logic-high voltage to turn on the switch. Pull EN_SW low or leave unconnected to place the switch in shutdown. EN_SW is internally pulled to SGND through a 1µA current sink. 18 EN_PROT — Protector Enable Input. Drive EN_PROT low to force GATE low and turn off the external n-channel MOSFET. EN_PROT is internally pulled to SGND by a 1µA sink current. Connect EN_PROT to IN for normal operation. 19, 20 IN IN Regulator Input. Bypass IN to SGND with a 10µF capacitor with an ESR < 1.5Ω. 21, 22 OUT_LDO OUT_LDO LDO Regulator Output. Bypass OUT_LDO to SGND with a ceramic capacitor with a minimum value of 22µF. OUT_LDO has a fixed 5V output or can be adjusted from1.8V to 11V. See the Setting the Output Voltage section. OC_DELAY Switch Overcurrent Blanking Time Programming Input. Leave OC_DELAY unconnected to select the minimum delay timeout before turning the switch off. OC_DELAY is internally pulled to SGND through a 1µA current source. See the Programming the Switch Overcurrent Blanking Time section. 23 24 OC_DELAY ILIM ILIM Switch Current-Limit Set Input. Connect a 10kΩ to 200kΩ resistor from ILIM to SGND to select the current limit for the internal switch. Connect ILIM to OUT_LDO to select the internal 170mA (min) current-limit threshold. Do not leave ILIM unconnected. See the Setting the Switch Current Limit section. Active-Low Hold Input. If EN_LDO is high when HOLD is forced low, the regulator latches the state of the EN_LDO input and allows the regulator to remain turned on when EN_LDO is subsequently pulled low. To shut down the regulator, release HOLD after EN_LDO is pulled low. If HOLD functionality is unused, connect HOLD to OUT_LDO or leave unconnected. HOLD is internally pulled up to OUT_LDO through a 0.6µA current source. See the Control Logic section. 25 HOLD HOLD 27, 28 OUT_SW OUT_SW — EP EP Switch Output. Bypass OUT_SW to SGND with a minimum 0.1µF ceramic capacitor. Exposed Pad. Connect EP to SGND plane. EP also functions as a heatsink to maximize thermal dissipation. Do not use as the main ground connection. ______________________________________________________________________________________ 11 MAX15009/MAX15011 Pin Description (continued) Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011 Functional Diagram IN VIN ENABLE LDO HOLD LDO IN VREF 1.235V BIAS AND VOLTAGE REFERENCE EN_LDO HOLD CONTROL LOGIC 5V LDO OUTPUT OUT_LDO M U X FB_LDO 0.124V 2μA CT 0.925 x VREF RESET VREF RESET OUTPUT OUT_LDO ILIM SWITCH 16μA OUT_SW VGATE SWITCH OUTPUT OUT_SW VREF S ENABLE SWITCH EN_SW Q 0.1V R OC_DELAY 1μA IN GATE UVLO 4.75V VIN GATE VREF ENABLE PROTECTOR EN_PROT SOURCE OVERVOLTAGE PROTECTOR (MAX15009 ONLY) EP 12 SGND PROTECTOR OUTPUT FB_PROT PGND ______________________________________________________________________________________ Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector The MAX15009/MAX15011 integrate a 300mA LDO voltage regulator, a current-limited switched output, and an OVP controller (MAX15009 only). These devices operate over a wide supply voltage range from 5V to 40V and are able to withstand load-dump transients up to 45V. The MAX15009/MAX15011 feature a 300mA LDO regulator that consumes 70µA of current under light-load conditions and feature a fixed 5V or an adjustable output voltage (1.8V to 11V). Connect FB_LDO to ground to select a fixed 5V output voltage or select the LDO output voltage by connecting an external resistive voltage-divider at FB_LDO. The regulator sources at least 300mA of current and includes a current limit of 330mA (min). Enable the LDO by pulling EN_LDO high. The switch features accurate current-limit sensing circuitry and is capable of controlling remote loads. Once enabled, an internal charge pump generates the overdrive voltage for an internal MOSFET. The switch then starts to conduct and OUT_SW is charged up to VOUT_LDO. The switch is enabled when the output voltage of the LDO is above the RESET threshold voltage (92.5% of the LDO nominal output value). An overcurrent condition exists when the current at OUT_SW, IOUT_SW, exceeds the 200mA (typ) internal factory-set current-limit threshold or the externally adjustable current-limit threshold. During a continuous overcurrent event, the capacitor connected at OC_DELAY, COC_DELAY, is charged up to a voltage of 1.235V with a current, IOC_DELAY_UP. When this voltage is reached, an overcurrent latch is set and the gate of the internal MOSFET is discharged, reducing IOUT_SW. COC_DELAY is then discharged through a pulldown current, IOC_DELAY_DOWN (IOC_DELAY_UP / 16) and the internal MOSFET remains off until COC_DELAY has been discharged to 0.1V. After this user-programmable turnoff delay, the switch turns back on. This charge/ discharge is repeated if the overcurrent condition persists. The switch returns to normal operation once the overcurrent condition has been removed. The OVP controller (MAX15009 only) relies on an external MOSFET with adequate voltage rating (VDSS) to protect downstream circuitry from overvoltage transients. The OVP controller drives the gate of the external n-channel MOSFET, and is configurable to operate as an overvoltage protection switch or as a closed-loop voltage limiter. GATE Voltage (MAX15009 Only) The MAX15009 uses a high-efficiency charge pump to generate the GATE voltage for the external n-channel MOSFET. Once the input voltage, VIN, exceeds the undervoltage lockout (UVLO) threshold, the internal charge pump fully enhances the external n-channel MOSFET. An overvoltage condition occurs when the voltage at FB_PROT goes above the threshold voltage, VTH_PROT. After VTH_PROT is exceeded, GATE is quickly pulled to PGND with a 63mA pulldown current. The MAX15009 includes an internal clamp from GATE to SOURCE that ensures that the voltage at GATE never exceeds one diode drop below SOURCE during gate discharge. The voltage clamp also prevents the GATEto-SOURCE voltage from exceeding the absolute maximum rating for the VGS of the external MOSFET in case the source terminal is accidentally shorted to 0V. Overvoltage Monitoring (MAX15009 Only) The OVP controller monitors the voltage at FB_PROT and controls an external n-channel MOSFET, isolating, or limiting the load during an overvoltage condition. Operation in OVP switch mode or limiter mode depends on the connection between FB_PROT and the external MOSFET. Overvoltage Switch Mode When operating in OVP switch mode, the FB_PROT divider is connected to the drain of the external MOSFET. The feedback path consists of the voltage-divider tapped at FB_PROT, FB_PROT’s internal comparator, the internal gate charge pump/gate pulldown, and the external n-channel MOSFET (Figure 1). When the programmed overvoltage threshold is exceeded, the internal comparator quickly pulls GATE to ground and turns VIN IN GATE MAX15009 FB_PROT PROTECTOR OUTPUT SOURCE SGND Figure 1. Overvoltage-Limiter Switch Configuration (MAX15009) ______________________________________________________________________________________ 13 MAX15009/MAX15011 Detailed Description MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector off the external MOSFET, disconnecting the power source from the load. In this configuration, the voltage at the source of the MOSFET is not monitored. When the voltage at FB_PROT decreases below the overvoltage threshold, the MAX15009 raises the voltage at GATE, reconnecting the load to the power source. Overvoltage-Limiter Mode (MAX15009 Only) When operating in overvoltage-limiter mode, the feedback path consists of SOURCE, FB_PROT’s internal comparator, the internal gate charge pump/gate pulldown, and the external n-channel MOSFET (Figure 2). This configuration results in the external MOSFET operating as a hysteretic voltage regulator. During normal operation, GATE is enhanced 8.1V above VIN. The external MOSFET source voltage is monitored through a resistive voltage-divider between SOURCE and FB_PROT. When VSOURCE exceeds the adjustable overvoltage threshold, an internal pulldown switch discharges the gate voltage and quickly turns the MOSFET off. Consequently, the source voltage begins to fall. The VSOURCE fall time is dependent on the MOSFET’s gate charge, the internal charge-pump current, the output load, and any load capacitance at SOURCE. When the voltage at FB_PROT is below the overvoltage threshold by an amount equal to the hysteresis, the charge pump restarts and turns the MOSFET back on. In this way, the OVP controller attempts to regulate VSOURCE around the overvoltage threshold. SOURCE remains high during overvoltage transients and the MOSFET continues to conduct during an overvoltage event. The hysteresis of the FB_PROT comparator and the gate turn-on delay force the external MOSFET to operate in a switched on/off sequence during an overvoltage event. Exercise caution when operating the MAX15009 in voltage-limiting mode for long durations. Care must be taken against prolonged or repeated exposure to overvoltage events while delivering large amounts of load current as the power dissipation in the external MOSFET may be high under these conditions. To prevent damage to the MOSFET, implement proper heatsinking. The capacitor tied between SOURCE and ground may also be damaged if the ripple current rating for the capacitor is exceeded. 14 VIN IN GATE MAX15009 PROTECTOR OUTPUT SOURCE FB_PROT SGND Figure 2. Overvoltage Limiter (MAX15009) As the transient voltage decreases, the voltage at SOURCE falls. For fast-rising transients and very large MOSFETs, connect an additional capacitor from GATE to PGND. This capacitor acts as a voltage-divider working against the MOSFET’s drain-to-gate capacitance. If using a very low gate charge MOSFET, additional capacitance from GATE to ground might be required to reduce the switching frequency. Control Logic The MAX15009/MAX15011 LDO features two logic inputs, EN_LDO and HOLD, making these devices suitable for automotive applications. For example, when the ignition key signal drives EN_LDO high, the regulator turns on and remains on even if EN_LDO goes low, as long as HOLD is forced low and stays low after initial regulator power-up. In this state, releasing HOLD turns the regulator output (OUT_LDO) off. This feature makes it possible to implement a self-holding circuit without external components. Forcing EN_LDO low and HOLD high (or unconnected) places the regulator into shutdown mode, reducing the supply current to less than 16µA. Table 1 shows the state of OUT_LDO with respect to EN_LDO and HOLD. Leave HOLD unconnected or connect directly to OUT_LDO to allow the EN_LDO input to act as a standard on/off logic input for the regulator. ______________________________________________________________________________________ Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector EN_LDO HOLD OUT_LDO Initial State Low Don’t care OFF EN_LDO is pulled to SGND through an internal pulldown. HOLD is unconnected and is internally pulled up to OUT_LDO. The regulator is disabled. Turn-On State High Don’t care ON EN_LDO is externally driven high turning regulator on. HOLD is pulled up to OUT_LDO. Hold Setup State High Low ON HOLD is externally pulled low while EN_LDO remains high (latches EN_LDO state). Hold State Low Low ON EN_LDO is driven low or left unconnected. HOLD remains externally pulled low keeping the regulator on. Off State Low High or unconnected OFF HOLD is driven high or left unconnected while EN_LDO is low. The regulator is turned off and EN_LDO/HOLD logic returns to the initial state. OPERATION STATE COMMENT Applications Information Load Dump Most automotive applications run off a multicell 12V lead-acid battery with a nominal voltage that swings between 9V and 16V, depending on load current, charging status, temperature, and battery age, etc. The battery voltage is distributed throughout the automobile and is locally regulated down to voltages required by the different system modules. Load dump occurs when the alternator is charging the battery and the battery becomes disconnected. Power in the alternator (behaving now essentially as an inductor) flows into the distributed power system and elevates the voltage seen at each module. The voltage spikes have rise times typically greater than 5ms and decay within several hundred milliseconds but can extend out to 1s or more depending on the characteristics of the charging system. These transients are capable of destroying semiconductors on the first fault event. The MAX15009/MAX15011 feature load-dump transient protection up to +45V. Setting the Output Voltage The MAX15009/MAX15011 feature dual-mode operation: these devices operate in either a preset voltage mode or an adjustable mode. In preset voltage mode, internal feedback resistors set the linear regulator output voltage (VOUT_LDO) to 5V. To select the preset 5V output voltage, connect FB_LDO to SGND. To select an adjustable output voltage between 1.8V and 11V, use two external resistors connected as a voltage-divider to FB_LDO (Figure 3). Set the output voltage using the following equation: VIN IN OUT_LDO R1 MAX15009 MAX15011 FB_LDO R2 SGND Figure 3. Setting the LDO Output Voltage VOUT_LDO = VFB_LDO x (R1 + R2) / R2 where VFB_LDO = 1.235V and R2 ≤ 50kΩ. Setting the RESET Timeout Period The reset timeout period is adjustable to accommodate a variety of applications. Set the reset timeout period by connecting a capacitor, C RESET , between CT and SGND. Use the following formula to select the reset timeout period, tRESET: tRESET = CRESET x VCT_TH / ICT where t RESET is in seconds and C RESET is in µF. VCT_TH is the CT ramp threshold in volts and ICT is the CT ramp current in µA, as described in the Electrical Characteristics table. ______________________________________________________________________________________ 15 MAX15009/MAX15011 HOLD Truth/State Table Table 1. EN_LDO/H MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector Leave CT open to select a typical reset timeout of 19µs. To maintain reset accuracy, use a low-leakage type of capacitor. Setting the Switch Current Limit The switch block features accurate current-limit sensing circuitry. A resistor connected from ILIM to SGND can be used to select the current-limit threshold using the following relationship: ISW_LIM (mA) = RILIM (kΩ) x 1mA / kΩ where 20kΩ ≤ RILIM ≤ 200kΩ. Connect ILIM to OUT_LDO to select the default current limit of 200mA (typ). Programming the Switch Overcurrent Blanking Time The switch provides an adjustable overcurrent blanking time to allow the safe charge of large capacitive loads. When an overcurrent event is detected, a delay period elapses before the condition is latched and the internal MOSFET is turned off. This period is the overcurrent delay, tOC_DELAY. Set the overcurrent delay using the following equation: tOC_DELAY = COC_DELAY x VOC_DELAY / IOC_DELAY_UP where tOC_DELAY is in seconds and COC_DELAY is in µF. VOC_DELAY is the overcurrent delay timeout threshold voltage in volts and IOC_DELAY_UP is the overcurrent delay timeout pullup current in µA as seen in the Electrical Characteristics table. Ensure that the switch is not disabled due to a large startup inrush current by selecting a large enough value for overcurrent blanking time. Assume that the current available for charging the total switch output capacitance, COUT_SW, is the difference between the current-limit threshold value, ISW_LIM, and the nominal IN VIN PROTECTOR OUTPUT MAX15009 FB_PROT COC_DELAY ≥ IOC_DELAY_UP × VOUT_LDO × COUT_SW VOC_DELAY × (ISW_LIM − IOUT_SW_NOM) COC_DELAY also affects the length of time before the MAX15009/MAX15011 attempt to turn the switch back on. Set the autoretry delay using the following equation: tOC_RETRY = COC_DELAY x VOC_DELAY/IOC_DELAY_DOWN where tOC_RETRY is in seconds, COC_DELAY is in µF, VOC_DELAY is in volts, and IOC_DELAY_DOWN is in µA. COC_DELAY should be a low-leakage type of capacitor with a minimum value of 100pF. Setting the Overvoltage Threshold (MAX15009 Only) The MAX15009 provides an accurate means to set the overvoltage threshold for the OVP controller using FB_PROT. Use a resistive voltage-divider to set the desired overvoltage threshold (Figure 4). FB_PROT has a rising 1.235V threshold with a 4% falling hysteresis. Begin by selecting the total end-to-end resistance, RTOTAL = R3 + R4. Choose RTOTAL to yield a total current equivalent to a minimum of 100 x IFB_PROT (FB_PROT’s input maximum bias current) at the desired overvoltage threshold. See the Electrical Characteristics table. For example: With an overvoltage threshold (VOV) set to 20V, RTOTAL < 20V / (100 x IFB_PROT), where IFB_PROT is FB_PROT’s maximum 100nA bias current: RTOTAL < 2MΩ VIN GATE R5 DC load current at OUT_SW, IOUT_SW_NOM and select the COC_DELAY using the following relationship: IN GATE PROTECTOR OUTPUT MAX15009 SOURCE SOURCE R3 R6 FB_PROT SGND SGND Figure 4. Setting the Overvoltage Threshold (MAX15009) 16 ______________________________________________________________________________________ R4 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector where VTH_PROT is the 1.235V FB_PROT rising threshold and VOV is the desired overvoltage threshold. R4 = 124kΩ: RTOTAL = R3 + R4 where R3 = 1.88MΩ. Use a standard 1.87MΩ resistor. A lower value for total resistance dissipates more power, but provides better accuracy and robustness against external disturbances. Input Transients Clamping When the external MOSFET is turned off during an overvoltage event, stray inductance in the power path may cause additional input-voltage spikes that exceed the VDSS rating of the external MOSFET or the absolute maximum rating for the MAX15009. Minimize stray inductance in the power path using wide traces and minimize the loop area included by the power traces and the return ground path. For further protection, add a zener diode or transient voltage suppressor (TVS) rated below the absolute maximum rating limits (Figure 5). Select the external MOSFET with adequate voltage rating, VDSS, to withstand the maximum expected load-dump input voltage. The on-resistance of the MOSFET, RDS(ON), should be low enough to maintain a minimal voltage drop at full load, limiting the power dissipation of the MOSFET. During regular operation, the power dissipated by the MOSFET is: PNORMAL = ILOAD2 x RDS(ON) Normally, this power loss is small and is safely handled by the MOSFET. However, when operating the MAX15009 in overvoltage limiter mode under prolonged or frequent overvoltage events, select an external MOSFET with an appropriate power rating. During an overvoltage event, the power dissipation in the external MOSFET is proportional to both load current and to the drain-source voltage, resulting in high power dissipated in the MOSFET (Figure 6). The power dissipated across the MOSFET is: POV_LIMITER = VQ1 x ILOAD where VQ1 is the voltage across the MOSFET’s drain and source during overvoltage limiter operation, and ILOAD is the load current. VMAX VOV VIN + VQ1 - VSOURCE ILOAD IN IN GATE MAX15009 MAX15009 TVS VSOURCE LOAD TVS GATE SOURCE LOAD SOURCE FB_PROT SGND Figure 5. Protecting the MAX15009 Input from High-Voltage Transients SGND Figure 6. Power Dissipated Across MOSFETs During an Overvoltage Fault (Overvoltage Limiter Mode) ______________________________________________________________________________________ 17 MAX15009/MAX15011 External MOSFET Selection Use the following formula to calculate R4: R4 = VTH_PROT x RTOTAL / VOV MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector Calculate the discharge time, t1, using the following equation: 0.04 × VOV t1 = CSOURCE × ILOAD + IGATEPD GATE SOURCE t2 t3 t1 tOVP Figure 7. MAX15009 Timing Diagram Overvoltage-Limiter Mode Switching Frequency When the MAX15009 is configured in overvoltagelimiter mode, the external n-channel MOSFET is subsequently switched on and off during an overvoltage event. The output voltage at OUT_PROT resembles a periodic sawtooth waveform. Calculate the period of the waveform, tOVP, by summing three time intervals (Figure 7): tOVP = t1 + t2 + t3 where t1 is the VSOURCE output discharge time, t2 is the GATE delay time, and t3 is the VSOURCE output charge time. During an overvoltage event, the power dissipated inside the MAX15009 is due to the gate pulldown current, I GATEPD . This amount of power dissipation is worse when ISOURCE = 0 (CSOURCE is discharged only by the internal current sink). The worst-case internal power dissipation contribution in overvoltage limiter mode, P OVP , in watts can be approximated using the following equation: t POVP = VOV × 0.98 × IGATEPD × 1 t OVP where VOV is the overvoltage threshold voltage in volts and IGATEPD is 100mA (max) GATE pulldown current. Output Discharge Time (t1) When the voltage at SOURCE exceeds the adjusted overvoltage threshold, GATE’s internal pulldown is enabled until VSOURCE drops by 4%. The internal current sink, I GATEPD , and the external load current, I LOAD , discharge the external capacitance from SOURCE to ground. 18 where t 1 is in ms, V OV is the adjusted overvoltage threshold in volts, ILOAD is the external load current in mA, and IGATEPD is the 100mA (max) internal pulldown current of GATE. CSOURCE is the value of the capacitor connected between the source of the MOSFET and PGND in µF. GATE Delay Time (t2) When SOURCE falls 4% below the overvoltage-threshold voltage, the internal current sink is disabled and the internal charge pump begins recharging the external GATE voltage. Due to the external load, the SOURCE voltage continues to drop until the gate of the MOSFET is recharged. The time needed to recharge GATE and reenhance the external MOSFET is approximately: t 2 = Ciss × VGS( TH) + VF IGATE where t2 is in µs, Ciss is the input capacitance of the MOSFET in pF, and VGS(TH) is the GATE-to-SOURCE threshold voltage of the MOSFET in volts. VF is the 0.7V (typ) internal clamp diode forward voltage of the MOSFET in volts, and IGATE is the charge-pump current 45µA (typ). Any external capacitance between GATE and PGND adds up to Ciss. During t2, the SOURCE capacitance, CSOURCE, loses charge through the output load. The voltage across CSOURCE, ΔV2, decreases until the MOSFET reaches its VGS(TH) threshold. Approximate ΔV2 using the following formula: I ×t ΔV2 = LOAD 2 CSOURCE SOURCE Output Charge Time (t3) Once the GATE voltage exceeds the GATE-to-SOURCE threshold, VGS(TH), of the external MOSFET, the MOSFET turns on and the charge through the internal charge pump with respect to the drain potential, QG, determines the slope of the output voltage rise. The time required for the SOURCE voltage to rise again to the overvoltage threshold is: t3 = Crss × ΔVSOURCE IGATE ______________________________________________________________________________________ Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector Power Dissipation/Junction Temperature During normal operation, the MAX15009/MAX15011 have two main sources of internal power dissipation: the LDO and the switched output. The internal power dissipation due to the LDO can be calculated as: PLDO = (VIN − VOUT_LDO ) × (IOUT_LDO + IOUT_SW ) where VIN is the LDO input supply voltage in volts, VOUT_LDO is the output voltage of the LDO in volts, I OUT_LDO is the LDO total load current in mA, and IOUT_SW is the switch load current in mA. Calculate the power dissipation due to the switch as: PSW = ΔVSW × IOUT _ SW where ΔVSW is the switch dropout voltage in volts for the given IOUT_SW current in mA. The total power dissipation PDISS in mW as: PDISS = PLDO + PSW For prolonged exposure to overvoltage events, use the VIN voltage expected during overvoltage conditions. Under these circumstances the corresponding internal power dissipation contribution, POVP, calculated in the previous section should also be included in the total power dissipation, PDISS. For a given ambient temperature, T A, calculate the junction temperature, TJ, as follows: TJ = TA + PDISS x θJA where TJ and TA are in °C and θJA is the junction-toambient thermal resistance in °C/W as listed in the Absolute Maximum Ratings section. The junction temperature should never exceed +150°C during normal operation. Thermal Protection When the junction temperature exceeds TJ = +160°C, the MAX15009/MAX15011 shut down to allow the device to cool. When the junction temperature drops to +140°C, the thermal sensor turns all enabled blocks on again, resulting in a cycled output during continuous thermal-overload conditions. Thermal protection protects the MAX15009/MAX15011 from excessive power dissipation. For continuous operation, do not exceed the absolute maximum junction temperature rating of +150°C. ______________________________________________________________________________________ 19 MAX15009/MAX15011 where VSOURCE = (VOV x 0.04) + V2 in volts, and Crss is the MOSFET’s reverse transfer capacitance in pF. Any external capacitance between GATE and PGND adds up to Crss. Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector MAX15009/MAX15011 Typical Operating Circuits VOUT1 DC-DC MAX5073 VOUT2 CSOURCE 5V TO 40V INPUT GATE SOURCE FB_PROT PGND IN SGND CIN SWITCH OUTPUT OUT_SW LDO ON/OFF COUT_SW EN_LDO MAX15009 SWITCH ON/OFF PROTECTOR ON/OFF HOLD 5V 300mA EN_SW OUT_LDO EN_PROT FB_LDO HOLD μC RPU ILIM RESET/EN I/O RESET CT RILIM VCC COUT_LDO OC_DELAY CRESET COC_DELAY 5V TO 40V INPUT IN LDO ON/OFF SWITCH ON/OFF HOLD COUT_SW EN_LDO MAX15011 VCC COUT_LDO EN_SW FB_LDO RPU μC HOLD RESET CT OC_DELAY CRESET 20 5V 300mA OUT_LDO ILIM RILIM SWITCH OUTPUT OUT_SW CIN RESET/EN I/O PGND SGND COC_DELAY ______________________________________________________________________________________ Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector ILIM OC_DELAY OUT_LDO OUT_LDO IN IN N.C. EN_SW 23 22 21 20 19 18 17 HOLD 25 16 EN_LDO N.C. 26 15 FB_LDO OUT_SW 27 14 N.C. 13 N.C. 12 N.C. OUT_SW 28 MAX15011 N.C. 29 N.C. 30 N.C. 31 *EP + 4 5 6 7 8 N.C. SGND PGND RESET N.C. N.C. 3 N.C. 2 N.C. N.C. 32 1 LDO SWITCHED OUTPUT MAX15009 √ √ √ MAX15011 √ √ — PART 24 TOP VIEW Selector Guide 11 N.C. 10 N.C. 9 CT OVP CONTROLLER Chip Information PROCESS: BiCMOS TQFN (5mm x 5mm) *EP = EXPOSED PAD ______________________________________________________________________________________ 21 MAX15009/MAX15011 Pin Configurations (continued) 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.) QFN THIN.EPS MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector 22 ______________________________________________________________________________________ Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector ______________________________________________________________________________________ 23 MAX15009/MAX15011 Package Information (continued) (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.) MAX15009/MAX15011 Automotive 300mA LDO Regulators with Switched Output and Overvoltage Protector Revision History REVISION NUMBER REVISION DATE 0 8/07 Initial release 1 1/08 Removed future product asterisks, updated Electrical Characteristics table and Typical Operating Characteristics section. DESCRIPTION PAGES CHANGED — 1, 2, 6, 8 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. 24 ____________________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.
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