EVALUATION KIT AVAILABLE MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch General Description The MAX16948 is a dual high-voltage, current-sensing low dropout linear regulator (LDO)/switch designed to operate with an input voltage range from 4.5V to 28V (45V load dump tolerant). The device provides phantom power over coax cable to remote radio frequency low-noise amplifiers (LNAs) in automotive systems with a maximum current of 300mA per channel. The device also provides a fixed regulated output voltage of 8.5V or an adjustable 1V to 12.5V output voltage. The device can also be configured as a switch. The device monitors the load current and provides an analog output current proportional to the sensed load current. Accurate internal current limits pro tect the input supply against both overcurrent and short-circuit conditions. The device features an open-drain error output for each channel to indicate to the microcontroller (FC) when a fault has occurred. The device features short-to-battery protection to latch off the internal LDO/switch during a short-to-battery event. During a thermal overload, the device reduces power dissipation by going into thermal shutdown. It includes two independent active-low, high-voltage-compatible shutdown inputs to place each channel in a low-power shutdown mode. The device is available in a 16-pin TQFN package with exposed pad, a 16-pin QSOP package with exposed pad, or a 16-pin QSOP package and is fully specified over the -40NC to +105NC temperature range. Features S2-Channel LDO/Switch with Precision-Adjustable Current-Sense (Up to 300mA Per Channel) SWide Input Voltage Range: 4.5V to 28V (45V Load Dump Tolerant) SOn/Off Switching or Regulation of Phantom Power Under µC Control SReverse Current Protection SOutput Short-to-Battery Protection SLoad Current Monitoring to Detect Open-Load/ Normal/Short-Circuit Conditions SOpen-Drain Error Status Signaling to µC SInput Overvoltage Shutdown SHigh Power-Supply Rejection Ratio (73dB) Applications Remote LNA Phantom Power Automotive Camera and Sensor Power Ordering Information appears at end of data sheet. For related parts and recommended products to use with this part, refer to www.maximintegrated.com/MAX16948.related. Typical Operating Circuits BATTERY INPUT DIN CIN1 µC SUPPLY CIN2 IN RPU1 LOUT1 RPU2 R11 ERR1 ERROR FLAGS REG RSENSE1 COUT1 DOUT1 RLOAD1 CLOAD2 RLOAD2 R21 LIM1 CLIM1 CSENSE1 RLIM2 LOUT2 CABLE2 LLOAD2 OUT2 SENSE2 RSENSE2 CLOAD1 MAX16948 SENSE1 CURRENT-SENSE OUTPUTS TO ADC LLOAD1 FB1 ERR2 CREG CABLE1 OUT1 R12 CSENSE2 COUT2 DOUT2 FB2 OFF ON R22 SHDN1 SHDN2 GND LIM2 CLIM2 RLIM2 Typical Operating Circuits continued at end of data sheet. 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. 19-6054; Rev 2; 5/13 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) IN, SHDN1, SHDN2................................................-0.3V to +45V ERR1, ERR2, REG................................................ -0.3V to +6.0V FB1, FB2, SENSE1, SENSE2, LIM1, LIM2... -0.3V to (VREG + 0.3V) OUT1, OUT2...........................................................-0.3V to +20V Continuous Power Dissipation (TA = +70NC) TQFN-EP (derate 25.0mW/NC above +70NC).............2000mW QSOP-EP (derate 22.7mW/NC above +70NC)............1818mW QSOP (derate 9.5mW/NC above +70NC)......................762mW Operating Temperature Range........................ -40NC to +105NC Storage Temperature Range............................ -65NC to +150NC Junction Temperature......................................................+150NC Lead Temperature (soldering, 10s).................................+300NC Soldering Temperature (reflow).......................................+260NC PACKAGE THERMAL CHARACTERISTICS (Note 1) TQFN-EP Junction-to-Ambient Thermal Resistance (BJA)...........40NC/W Junction-to-Case Thermal Resistance (BJC)..................6NC/W 16 QSOP-EP Junction-to-Ambient Thermal Resistance (BJA)...........44NC/W Junction-to-Case Thermal Resistance (BJC)..................6NC/W 16 QSOP Junction-to-Ambient Thermal Resistance (BJA).........105NC/W Junction-to-Case Thermal Resistance (BJC)................37NC/W Note 1: 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 = 14V, TA = TJ = -40NC to +105NC, unless otherwise noted. Typical values are at TA = TJ = +25NC.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 4.5 28 45 2.1 3.4 mA 7 FA POWER SWITCH/LDO IN Operating Supply Range VIN Over 19V, output and current sense is switched off (Note 3) Output switched off, for < 1s (Note 3) IN Supply Current in Operation IIN VSHDN1/SHDN2 > 2.8V, TA = +25NC IN Supply Current in Shutdown ISD SHDN1 = SHDN2 = GND, TA = +25NC, VIN = 12V IN Undervoltage Lockout VUVL IN Undervoltage Lockout Hysteresis VUVL-HYS Voltage Drop of Internal Switch VIN - VOUT1/OUT2 VIN rising VIN falling 3.8 4.45 390 Measured between IN and OUT1/OUT2, IOUT1/OUT2 = 100mA, FB1/FB2 = GND, SW operation VIN R 5V, TA = +105NC (Note 4) Measured between IN and OUT1/OUT2, IOUT1/OUT2 = 100mA, FB1/FB2 = GND, SW operation VIN R 5V, TA = +25NC Maxim Integrated 4.8 V V mV 0.3V V 0.145 0.220 2 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch ELECTRICAL CHARACTERISTICS (continued) (VIN = 14V, TA = TJ = -40NC to +105NC, unless otherwise noted. Typical values are at TA = TJ = +25NC.) (Note 2) PARAMETER Feedback Voltage Input Bias Current to FB1 and FB2 SYMBOL VFB IFB1/FB2 CONDITIONS MIN TYP MAX UNITS For LDO mode with external resistive dividers, IOUT1/OUT2_= 5mA to 150mA 0.97 1 1.03 V VFB1/FB2 = 1.0V, LDO mode, TA = +25NC -0.5 +0.5 FA VREG 1.7 VREG 0.8 V 1 12.5 V Feedback Threshold for Internal Feedback Resistive Divider VFB1/FB2,TH Switching to LDO mode with internal 8.5V resistive dividers Adjustable Output Voltage Range VOUT1/OUT2 LDO mode with external resistive dividers (Notes 3, 5) FB1 and FB2 Load Regulation DVFB, LOAD VIN - VOUT1/OUT2 R 2V, IOUT1/OUT2 = 5mA to 250mA, LDO mode (Note 3) FB1 and FB2 Line Regulation DVFB, LINE VIN - VOUT1/OUT2 R 2V, IOUT1/OUT2 = 50mA, LDO mode (Note 3) VOUT1/OUT2, 8.5V IOUT1/OUT2 = 70mA, LDO mode with internal resistive divider, 9V < VIN < 18V Fixed Output Voltage 8.5V Power-Supply Rejection Ratio PSRR 8.33 VIN - VOUT1/OUT2 R 2V, IOUT1/OUT2 = 10mA at f = 100Hz, LDO mode VOUT1/OUT2 = 8.5V, VRIPPLE = 0.5VP-P (Note 3) -7 mV 100 FV/V 8.5 8.67 73 V dB CURRENT SENSE SENSE1 to OUT1 and SENSE2 to OUT2 Current Ratio AI VSENSE1/SENSE2 < 3V IOUT1/OUT2 = 100mA, VIN = 5V, 19V 0.485 0.5 0.515 50mA P IOUT1/OUT2 P 300mA, VIN R 5V (Note 3) 0.45 0.5 0.55 20mA P IOUT1/OUT2 P 50mA, VIN R 5V (Note 3) 0.415 0.5 0.585 5mA P IOUT1/OUT2 P 20mA, VIN R 5V (Note 3) 0.325 0.5 0.675 0mA P IOUT1/OUT2 P 5mA, VIN R 5V (Notes 3, 6) 0.3 0.5 0.7 2 10 FA 2 FA No-Load Current-Sense Offset ICSO IOUT1 = IOUT2 = 0mA (Note 3) SENSE1, SENSE2, LIM1, LIM2 Leakage Current ILEAK SHDN1 = SHDN2 = GND, TA =+ 25NC Maxim Integrated % 3 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch ELECTRICAL CHARACTERISTICS (continued) (VIN = 14V, TA = TJ = -40NC to +105NC, unless otherwise noted. Typical values are at TA = TJ = +25NC.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 2.375 2.5 2.625 V 21 23 V FAILURE DETECTION LIM1 and LIM2 Current-Limit Threshold Voltage VLIM1/LIM2,TH Voltage on LIM1 and LIM2 for which output current is limited IN Overvoltage Lockout Threshold (Rising) VOVLO,R VIN rising 19 IN Overvoltage Lockout Threshold (Falling) VOVLO,F VIN falling 18.5 IN Overvoltage Lockout Hysteresis VOVLO,H Short-to-BAT Threshold in Off State Reverse Current Detection Level VS2B IREVCUR 600 mV VOUT1/OUT2 - VIN, checked during turnon sequence -500 -80 +110 mV Power FET on (SW or LDO mode) -100 -50 -1 mA 4.16 20 Fs tPD-RC Delay to shutdown the switch or LDO after drop over RON becomes negative, IOUT1/OUT2 = -200mA (typ), TA = +25NC Reverse Current Blanking Time tBLK-RC Blanking time for reverse current and FB1/FB2 out of range after rising edge of SHDN1, SHDN2, or current limiting event is over Feedback Voltage Out of Range VFBERR LDO mode, internal pulldown resistor switched on, FB rising Feedback Voltage Out-ofRange Hysteresis VFBERR-HYS LDO mode, internal pulldown resistor switched on (Note 3) Reverse Current (Short-to-BAT) Shutdown Delay V 16 1.12 ms 1.15 1.28 V 39 100 mV OVERTEMPERATURE PROTECTION (Note 3) Thermal Shutdown Thermal Shutdown Hysteresis TSHDN 160 NC TSHDN-HYS 15 NC SUPPORTING CIRCUITS, INTERFACE SIGNALS Internal Voltage Regulator VREG TA = +25NC, IREG = 0mA, VIN = 4.5V to 18V 4 5 5.5 V TA = +25NC, IREG = 0mA, VIN = 6.5V to 18V 4.5 5 5.5 V 15 Internal Voltage Regulator Current Limit IREG (Note 4) ERR1 and ERR2 OutputVoltage Low VOL Sinking current = 10mA ERR1 and ERR2 Open-Drain Leakage Current ERR1 and ERR2 not asserted, VERR1/ ERR2 = 5V, TA = +25NC SHDN1 and SHDN2 High VSHDN1/SHDN2,HI SHDN1 and SHDN2 Low VSHDN1/SHDN2,LO Maxim Integrated mA 0.4 V 1 FA 0.8 V 2.8 V 4 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch ELECTRICAL CHARACTERISTICS (continued) (VIN = 14V, TA = TJ = -40NC to +105NC, unless otherwise noted. Typical values are at TA = TJ = +25NC.) (Note 2) PARAMETER SYMBOL SHDN1 and SHDN2 Pulldown Resistance CONDITIONS RSHDN Startup Response Time tST OUT Pulldown Resistor ROUT1/OUT2-OFF MIN TYP MAX UNITS VSHDN1/SHDN2 = 2V 500 kI SHDN1 and SHDN2 rising to turn on LDO/switch (Note 3) 300 Fs SHDN1 = SHDN2 = GND 56 kI 2: Devices are tested at TA = +25NC and guaranteed by design for TA = TMIN to TMAX. 3: Guaranteed by design; not production tested. 4: Guaranteed by ATE characterization. Limits are not production tested. 5: In case of OUT1/OUT2 shorted to BAT, feedback network must protect FB1/FB2 from violating their absolute maximum ratings. For OUT1/OUT2 set below 3.3V, use an additional 5V clamp on FB1/FB2 with low parasitic capacitance. Note 6: Limits do not include current-sense offset. Note Note Note Note Typical Operating Characteristics (VIN = 14V, TA = +25NC, see the Typical Operating Circuits, unless otherwise noted.) VOLTAGE DROP OF INTERNAL SWITCH vs. OUTPUT CURRENT VIN - VOUT (mV) 5.5 5.0 TA = +105°C 400 TA = +25°C 300 200 4.5 100 4.0 -45 -20 5 30 55 80 500 MAX16948 toc03 TA = +105°C 400 TA = +25°C 300 200 100 TA = -40°C TA = -40°C 0 0 105 VOUT = 5V FB_ = EXTERNAL 600 0 50 100 150 200 250 50 0 300 100 150 200 250 300 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) DROPOUT VOLTAGE vs. OUTPUT CURRENT VOLTAGE DROP OF INTERNAL SWITCH vs. SUPPLY VOLTAGE POWER-SUPPLY REJECTION RATIO vs. FREQUENCY 7.8 VIN - VOUT (mV) TA = +105°C 400 TA = +25°C 7.7 100 0 0 50 100 150 200 OUTPUT CURRENT (mA) Maxim Integrated 250 -30 7.5 7.4 300 VOUT_ = 5V FB_ = EXTERNAL RESISTIVE DIVIDER VRIPPLE_ = 0.5VP-P IOUT_ = 10mA -40 -50 -60 -70 OUT2 7.2 TA = -40°C -20 OUT1 7.6 7.3 200 -10 PSRR (dB) 500 FB_ = GND IOUT_ = 5mA 7.9 0 MAX16948 toc05 600 300 8.0 MAX16948 toc04 FB_ = REG MAX16948 toc06 TEMPERATURE (°C) 700 DROPOUT VOLTAGE (mV) FB_ = GND 600 500 6.0 DROPOUT VOLTAGE vs. OUTPUT CURRENT 700 DROPOUT VOLTAGE (mV) SHDN1 = SHDN2 = GND 6.5 SHUTDOWN CURRENT (µA) 700 MAX16948 toc01 7.0 MAX16948 toc02 SHUTDOWN CURRENT vs. TEMPERATURE -80 7.1 -90 7.0 -100 0 5 10 SUPPLY VOLTAGE (V) 15 20 0.01 1 100 10,000 FREQUENCY (kHz) 5 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch Typical Operating Characteristics (continued) (VIN = 14V, TA = +25NC, see the Typical Operating Circuits, unless otherwise noted.) POWER-UP WAVEFORM (FB_ = REG, IOUT_ = 90mA) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY -10 -20 MAX16948 toc08 MAX16948 toc07 0 FB_ = REG VRIPPLE_ = 0.5VP-P IOUT_ = 10mA VIN 10V/div PSRR (dB) -30 VOUT1 5V/div -40 -50 VOUT2 5V/div -60 -70 -80 -90 0.01 1 100 100µs/div 10,000 FREQUENCY (kHz) POWER-UP WAVEFORM (FB_ = GND, IOUT_ = 90mA) STARTUP WAVEFORM (FB_ = REG, IOUT_ = 90mA) MAX16948 toc09 MAX16948 toc10 VIN 10V/div VSHDN1 AND VSHDN2 5V/div VOUT1 10V/div VOUT1 5V/div VOUT2 10V/div VOUT2 5V/div 200µs/div 100µs/div STARTUP WAVEFORM (FB_ = GND, IOUT_ = 90mA) VSHDN1 AND VSHDN2 5V/div VOUT1 10V/div VOUT2 10V/div 200µs/div CURRENT-SENSE AMPLIFIER GAIN (%) 0.504 0.502 MAX16948 toc12 CURRENT-SENSE AMPLIFIER GAIN vs. TEMPERATURE MAX16948 toc11 FB_ = GND IOUT_ = 100mA 0.500 0.498 SENSE2 0.496 SENSE1 0.494 0.492 -45 -20 5 30 55 80 105 TEMPERATURE (°C) Maxim Integrated 6 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch Typical Operating Characteristics (continued) (VIN = 14V, TA = +25NC, see the Typical Operating Circuits, unless otherwise noted.) CURRENT-SENSE AMPLIFIER GAIN vs. OUTPUT CURRENT CURRENT-SENSE AMPLIFIER ERROR vs. OUTPUT CURRENT 0.501 SENSE2 0.500 0.499 0.498 0.497 SENSE1 0.496 0.495 0.494 0.493 0.6 FB = GND 0.492 0 50 100 150 200 250 MAX16948 toc14 0.502 CURRENT-SENSE AMPLIFIER ERROR (%) MAX16948 toc13 CURRENT-SENSE AMPLIFIER GAIN (%) 0.503 0.4 0.2 0 SENSE2 -0.2 -0.4 -0.6 SENSE1 -0.8 -1.0 -1.2 -1.4 FB = GND -1.6 300 0 OUTPUT CURRENT (mA) 50 100 MAX16948 toc16 5.0 4.5 3.5 4.0 3.0 VREG (V) VSENSE_ (V) 300 5.5 MAX16948 toc15 4.0 2.5 2.0 3.5 3.0 2.5 1.5 1.0 2.0 0.5 1.5 0 1.0 0 1 2 3 4 0 RSENSE_ (kΩ) 1ms/div 30 40 MAX16948 toc18 VIN 10V/div 10V 20 LINE TRANSIENT (VOUT_ = 5V, IOUT_ = 50mA) MAX16948 toc17 18V 10 IREG (mA) LINE TRANSIENT (FB_ = REG, IOUT_ = 50mA) Maxim Integrated 250 VREG vs. IREG FB_ = GND IOUT_ = 300mA 4.5 200 OUTPUT CURRENT (mA) VSENSE_ vs. RSENSE_ 5.0 150 18V VIN 10V/div 10V VOUT1 (AC-COUPLED) 10mV/div VOUT1 (AC-COUPLED) 10mV/div VOUT2 (AC-COUPLED) 10mV/div VOUT2 (AC-COUPLED) 10mV/div 1ms/div 7 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch 16 FB1 MAX16948 OUT1 2 15 LIM1 SHDN1 3 SENSE2 + ERR2 N.C. 1 TOP VIEW ERR1 TOP VIEW SENSE1 Pin Configurations 12 11 10 9 LIM1 13 8 LIM2 7 FB2 6 REG 5 GND 14 SENSE1 FB1 14 IN 4 13 ERR1 SHDN2 5 12 ERR2 MAX16948 N.C. 15 OUT1 16 11 SENSE2 OUT2 6 9 FB2 SHDN1 *EP QSOP-EP/QSOP 2 3 4 OUT2 1 REG 8 SHDN2 10 LIM2 IN GND 7 *EP + TQFN (4mm × 4mm) *CONNECT EP TO GND. Pin Descriptions PIN QSOP/ QSOP-EP TQFN-EP 1 15 NAME N.C. FUNCTION No Connection. Not internally connected. 2 16 OUT1 LDO/Switch Output 1 to Remote Load. Bypass OUT1 to GND with >1FF in parallel with 100nF low-ESR ceramic capacitors for regulator stability. 3 1 SHDN1 Active-Low Shutdown Input for OUT1. SHDN1 is pulled to GND with an internal 500kI resistor. 4 2 IN 5 3 SHDN2 6 4 OUT2 LDO/Switch Output 2 to remote load. Bypass OUT2 to GND with >1FF in parallel with 100nF low-ESR ceramic capacitors for regulator stability. 7 5 GND Ground 8 6 REG Internal 5V Regulator. Provides supply for internal low-voltage blocks, SENSE_, and LIM_ outputs. FB2 Feedback Input for Setting the OUT2 Voltage. Connect FB2 to GND to select current-limited switch operation. Connect to an external resistive divider for adjustable output-voltage operation. Connect FB2 to REG to choose the internal resistive divider for the 8.5V regulator option. 9 Maxim Integrated 7 Input Voltage. Bypass IN to GND with an electrolytic capacitor with a minimum value of 10FF and a low-ESR ceramic capacitor with a minimum value of 0.1FF. Active-Low Shutdown Input for OUT2. SHDN2 is pulled to GND with an internal 500kI resistor. 8 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch Pin Descriptions (continued) PIN QSOP/ QSOP-EP TQFN-EP NAME LIM2 FUNCTION Output of Current Sense for Limiting. This output is proportional to current flowing through OUT2. The internal current-limit amplifier is tripped when the voltage on LIM2 reaches 2.5V. Connect a resistor to GND to set the level for current limitation and a 0.1FF capacitor in parallel for frequency compensation of the current-limit loop. 10 8 11 9 SENSE2 12 10 ERR2 Open-Drain Fault Indicator Output 2 13 11 ERR1 Open-Drain Fault Indicator Output 1 14 12 SENSE1 15 13 Output of Current Sense for Sensing. The current of SENSE2 is proportional to the current flowing through OUT2. Connect a resistor from SENSE2 to GND to set the output voltage level. Additionally, connect a 0.1FF capacitor from SENSE2 to GND. Output of Current Sense for Sensing. The current of SENSE1 is proportional to the current flowing through OUT1. Connect a resistor from SENSE1 to GND to set the output voltage level. Additionally, connect a 0.1FF capacitor from SENSE1 to GND. LIM1 Output of Current Sense for Limiting. This output is proportional to current flowing through OUT1. The internal current-limit amplifier is tripped when the voltage on LIM1 reaches 2.5V. Connect a resistor to GND to set the level for current limitation and a 0.1FF capacitor in parallel for frequency compensation of the current-limit loop. 16 14 FB1 Feedback Input for Setting the OUT1 Voltage. Connect FB1 to GND to select current-limited switch operation. Connect to an external resistive divider for adjustable output-voltage operation. Connect FB1 to REG to choose the internal resistive divider for the 8.5V regulator option. — — EP Exposed Pad (MAX16948A only). Connect EP to the ground plane for optimal heat dissipation. Do not use EP as the primary electrical ground connection. Maxim Integrated 9 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch Functional Diagram 2x OUT1/ OUT2 IN I-SENSE CHARGE PUMP REF I-LIM (2.5V) FB (1.0V) CURRENT LIMIT REVERSE I DIAGNOSTICS OUT > IN FB > 1.2V FB1/ FB2 SHDN1 OUT_ > IN_ SHDN2 CONTROL FB_ > 110% ERR1 ERR2 IN CURRENT SOURCES TEMPERATURE SENSOR 21V MAX16948 LIM1/ LIM2 SENSE1 SENSE2 Detailed Description The MAX16948 is a dual high-voltage, current-sensing LDO/switch designed to operate with an input voltage range from 4.5V to 28V (45V load dump tolerant). The device provides phantom power over coax cable to remote radio frequency low-noise amplifiers (LNAs) in automotive systems with a maximum current of 300mA per channel. The device also provides a fixed regulated output voltage of 8.5V, an adjustable 1V to 12.5V output voltage, or the device can be configured as a switch. The device is ideal for providing phantom power to remote radio-frequency LNAs in automotive applications. Maxim Integrated REF, REG REG GND The device monitors the load current, and its currentsense outputs provide a current proportional to the sensed load current. An accurate programmable current limit pro tects the input supply against both overcurrent and short-circuit conditions. The device features open-drain fault indicator outputs and overtemperature shutdown. The device features short-to-battery protection to latch off the internal LDO/switch during a short-to-battery event. During a thermal overload, the device reduces power dissipation by going into thermal shutdown. It includes dual independent, active-low, high-voltage-compatible shutdown inputs to place each channel in a low-power shutdown mode. 10 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch Fault Detection The device monitors the load current through an internal sense resistor to protect against short-circuit, short-tobattery, and reverse current faults. In addition, the device also detects input and output overvoltage conditions and features thermal shutdown. Short Circuit and Overcurrent The current limit of each channel is programmed with an external resistor connected to the output of the current sense amplifiers LIM_ to protect the device during short-circuit or overcurrent conditions. When the voltage at LIM_ reaches the internal 2.5V threshold, the output current of the LDO/switch is limited, and ERR_ asserts low but the output is not disabled. The ERR_ and LIM_ outputs should be monitored by the FC, and the channel experiencing the short-circuit or overcurrent condition should be disabled by pulling SHDN_ low. If this condition persists, thermal shutdown could occur and both outputs could be disabled. Short-to-Battery and Reverse Current Detection It is possible for OUT_ to be shorted to the battery due to a fault in the system. Each channel detects this failure by comparing the voltage at OUT_ and IN before the switch turns on. Every time the LDO/switch is enabled on the rising edge of SHDN_ or during the exiting of thermal shutdown, the short-to-battery detection is performed. At this point, if the device detects the short-to-battery fault, the LDO/switch stays off and ERR_ is asserted low. The fault is latched, and the startup resumes when the shortto-battery fault is removed and SHDN_ is toggled. During normal operation if a short-to-battery fault results in reverse current for more than 5Fs (typ) the LDO/switch is latched off and ERR_ is asserted low. To remove the latched condition after a short-to-battery (reverse current) fault, the fault condition must first be removed and SHDN_ must be toggled. Series inductance and the output capacitor can produce ringing during large load transients when enabling the LDO/switch, resulting in an output voltage that temporarily exceeds the input voltage. Blanking is implemented during startup. The reverse current blanking time (tREV_BLANK) is 16ms (typ). When the MAX16948 is operated with input voltage close to the output voltage, as in switch mode operation or LDO mode in dropout, care must be taken to avoid a false reverse current detection in the presence of a short circuit to ground fault. If both channels are enabled and one channel is shorted to ground after startup, the current drawn from CIN may result in a temporary dip in the intput voltage, which may trigger the reverse current detection fault. To aovoid this false trigger event, use an electrolytic capacitor of at least 100FF. Thermal Shutdown Thermal shutdown circuitry protects the device from overheating. The switch turns off immediately when the junction temperature exceeds +160NC (typ). The switch turns on again after the device temperature drops by approximately 15NC (typ). FB Inputs (FB1/FB2) FB1 and FB2 control the output voltage on OUT1 and OUT2. Connect FB_ to GND to select current-limited switch operation. Connect to an external resistive divider for adjustable output voltage operation (feedback voltage 1V (typ)). Connect FB_ to REG to choose the internal resistive divider for the 8.5V regulator option. Table 1. Fault Response DEVICE STATUS VLIM_(V) VERR LDO/SW OUTPUT LATCHED Normal Operation 0 P VLIM_< 2.5 High Enabled No Short Circuit to GND or Overcurrent 2.5 Low Enabled No VOUT > VIN at Startup 0 Low Disabled Yes Reverse Current 0 Low Disabled Yes VFB > 1.2V 0 High Enabled No Input Overvoltage 0 Low Disabled No Thermal Shutdown 0 High Disabled No Maxim Integrated 11 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch Undervoltage and Overvoltage Lockout The device includes undervoltage lockout circuitry (UVLO) to prevent erroneous switch operation when the input voltage goes below 4.45V (max) during startup and brownout conditions. Input voltages of less than 4.45V inhibit operation of the device by turning off the internal charge pump and the switch. The device also features an overvoltage lockout (OVLO) threshold of +21V (typ). When VIN is greater than VOVLO, the device immediately turns off the switch and the internal charge pump. Shutdown (SHDN1, SHDN2) The device features two active-low shut down inputs (SHDN1, SHDN2) to place the device in a low-power shutdown mode. SHDN1 controls OUT1 and SHDN2 controls OUT2. The device turns off both channels and consumes a maximum of 7FA (at VIN = 12V) of shutdown current when both SHDN1 and SHDN2 are low. Driving SHDN1 and/or SHDN2 high initiates device turn-on with short-to-battery detection. SHDN1 and SHDN2 are pulled to GND with an internal 500kI resistor. Internal Voltage Regulator (REG) The device features an internal regulator that regulates the input voltage to +5V to power all internal circuitry. Bypass the regulator output (REG) to GND with a 1FF ceramic capacitor. The REG output can be used to supply external circuitry up to a maximum 15mA current. Applications Information/External Component Selection Fixed/Adjustable Output Voltage The device is configurable to provide a fixed 8.5V output or as an adjustable LDO with an output between 1V and 12.5V. Connect FB_ to REG to configure the device as an 8.5V LDO. Connect a resistive divider between OUT_, FB_, and GND to set the output to the desired voltage. FB_ is regulated to 1.0V with Q3% accuracy for a load current between 5mA and 150mA. Select a value for R2 and calculate R1 as follows: V = R1 OUT_ − 1R2 V FB_ where R2 must be less than or equal to 1kI. Select R1 and R2 such that the maximum input bias current at FB (±0.5FA) is negligible compared to the current flowing through R1 and R2. Maxim Integrated Current-Limit Resistor and Capacitor Selection The current-sense outputs at LIM1/LIM2 are proportional to the load current at OUT1/OUT2 and are internally connected to a current-limit comparator referenced to 2.5V. The desired current limit is set with an external resistor RLIM_using the following equation: 2.5(V) R LIM_(Ω) = 0.5% × ILOAD_MAX(A) A 0.1FF compensation capacitor CLIM_ must be placed in parallel with RLIM_ to establish a dominant pole in the current limiting loop to maintain stability and to prevent fast current transients from prematurely triggering the current limit. Current-Sense Resistor Selection The current-sense outputs SENSE1/SENSE2 are proportional to the load current at OUT1/OUT2. An output resistor RSENSE_ must be connected between SENSE1/ SENSE2 and GND to generate a current-sense voltage prior to sampling by an ADC. RSENSE is calculated using the following equation: VADC,FS (V) R SENSE_ (Ω) = 0.5% × ILOAD_MAX(A) where VADC,FS is the full-scale input voltage of the ADC. A 0.1FF capacitor CSENSE should be placed in parallel with RSENSE to hold the voltage during ADC sampling cycles. In addition to ADC sampling, open-load or overcurrent conditions can be detected by using external comparators and splitting RSENSE_ into a resistive divider as shown in Figure 1. In this circuit the outputs of comparators U1 and SENSE_ R3 VOC,TH U1 VOC U2 VOL MAX16948 R4 VOL,TH R5 Figure 1. Open-Load and Overcurrent Detection Circuit 12 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch Table 2. Open-Load and OvercurrentDetection Circuit States OC OL STATE 0 0 Normal Operation 0 1 Open-Load Condition 1 0 Overcurrent Condition 1 1 Invalid State U2 indicate the operating state of the circuit as shown in Table 2. The open-load and overcurrent limits are set using the following equations: VOL,TH (V) R5(Ω) = 0.5% × I OPEN−LOAD(A) where VOL,TH is the open-load voltage threshold for comparator U2 and IOPEN-LOAD is the desired open-load threshold for the current flowing through the LDO/switch. = R4(Ω) VOC,TH (V) 0.5% × I OVERCURRENT(A) − R5 where VOC,TH is the overcurrent voltage threshold for comparator U1. IOVERCURRENT is the desired overcurrent threshold for the current flowing through the LDO/ switch and the internal current limit should be programmed such that ILOAD_MAX > IOVERCURRENT. Input Capacitor Connect a parallel electrolytic capacitor and a low-ESR ceramic capacitor from IN to GND to limit the inputvoltage drop during momentary output short-circuit conditions and to protect the device against transients due to inductance on the IN line. For example, use at least a 0.1FF ceramic capacitor in parallel with a 10FF electrolytic capactior if the input inductance (including any stray inductance) is estimated to be 20FH. Larger capacitor values reduce the voltage undershoot and overshoot in case of reverse current. Output Capacitor Connect >1FF in parallel with 0.1FF low-ESR ceramic capacitors between OUT1/OUT2 and GND for regulator stability. These capacitors should be placed as close to the device as possible. Utilize capacitors with an X7R dielectric to ensure stability over the operating temperature range of the device. In an analogous fashion to the input capacitor, an output capacitor protects the device against transients due to any series inductance in the output. Under no conditions should the voltage on OUT1/OUT2 go below -0.3V as specified in the Absolute Maximum Ratings section. A Schottky diode is required as a clamp if transients are expected to go below ground. R3(Ω) = RSENSE_ - R4 - R5 The open-load voltage threshold VOL,TH and overcurrent threshold VOC,TH can be generated from REG utilizing a resistive divider. The thresholds should be selected such that VOC,TH > VOL,TH. Maxim Integrated 13 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch Typical Operating Circuits (continued) BATTERY INPUT 10µF 0.1µF 1µF µC SUPPLY IN 2.7kΩ REG 1mH 2.7kΩ LLOAD1 1µF ERR1 ERROR FLAGS CABLE1 OUT1 CLOAD1 RLOAD1 CLOAD2 RLOAD2 FB1 ERR2 MAX16948 LIM1 SENSE1 4kΩ 0.1µF 0.1µF 2.5kΩ CURRENT-SENSE OUTPUTS TO ADC 1mH SENSE2 4kΩ CABLE2 LLOAD2 OUT2 3kΩ 0.1µF 1µF FB2 750Ω OFF ON SHDN1 SHDN2 GND LIM2 0.1µF 2.5kΩ Ordering Information PART TEMP RANGE PIN-PACKAGE MAX16948AGTE/V+ -40NC to +105NC 16 TQFN-EP** MAX16948AGEE/V+ -40NC to +105NC 16 QSOP-EP** MAX16948BGEE/V+* -40NC to +105NC 16 QSOP /V denotes an automotive qualified part. +Denotes a lead(Pb)-free/RoHS-compliant package. *Future product—contact factory for availability. **EP = Exposed pad. Chip Information 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. 16 TQFN-EP T1644+4 21-0139 90-0070 16 QSOP-EP E16E+9 21-0112 90-0240 16 QSOP E16+5 21-0055 90-0167 PROCESS: BiCMOS Maxim Integrated 14 MAX16948 Automotive Dual Remote Antenna Current-Sense LDO/Switch Revision History REVISION NUMBER REVISION DATE DESCRIPTION 0 9/11 Initial release 1 4/12 Updated maximum output voltage 2 5/13 Added light-load current-sense specs to Electrical Characteristics table PAGES CHANGED — 1, 3, 10, 12 3 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. Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 © 2013 Maxim Integrated Products, Inc. 15 Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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