LT6658BHMSE-2.5#PBF

LT6658 Precision Dual Output, High Current, Low Noise, Voltage Reference FEATURES DESCRIPTION Dual Output Tracking Reference nn Each Output Configurable to 6V nn Output 1: 150mA Source/20mA Sink nn Output 2: 50mA Source/20mA Sink nn Low Drift: nn A-Grade: 10ppm/°C Max nn B-Grade: 20ppm/°C Max nn High Accuracy: nn A-Grade: ±0.05% Max nn B-Grade: ±0.1% Max nn Low Noise: 1.5ppm P-P (0.1Hz to 10Hz) nn Wide Operating Voltage Range to 36V nn Load Regulation: 0.25µV/mA nn AC PSRR: 96dB at 10kHz nn Kelvin Sense Connection on Outputs nn Thermal Shutdown nn Separate Supply Pins for Each Output nn Available Output Voltage Options: 1.2V, 1.8V, 2.5V, 3V, 3.3V, 5V. All Options are Adjustable nn Available in Exposed Pad Package MSE16 and 4mm × 3mm DFN The LT®6658 is a family of precision dual output references combining the performance of a precision voltage reference and a linear regulator that we call the Refulator™. Both outputs are ideal for driving the reference inputs of high resolution ADCs and DACs, even with heavy loading, while simultaneously powering microcontrollers and other circuitry. Both outputs have the same precision specifications and track each other over temperature and load. Each output can be configured with external resistors to give an output voltage up to 6V. nn APPLICATIONS Using Kelvin connections, the LT6658 typically has 0.1ppm/mA load regulation with up to 150mA load current. A noise reduction pin is available to band-limit and lower the total integrated noise. Separate supply pins are provided for each output, providing an option to reduce power consumption and isolate the buffer amplifiers. The outputs have excellent supply rejection and are stable with 1µF to 50µF capacitors. The LT6658 is available in a 16-lead MSOP and DFN with an exposed pad for thermal management. Short circuit and thermal protection help to prevent thermal overstress. All registered trademarks and trademarks are the property of their respective owners. Microcontroller or FPGA with ADC/DAC Applications Data Acquisition Systems nn Automotive Control and Monitoring nn Precision Low Noise Regulators nn Instrumentation and Process Control nn nn TYPICAL APPLICATION Output Voltage Temperature Drift Both Outputs 2.502 VIN 5V TO 36V VIN1 VOUT2_F VIN2 VOUT2_S RLOAD2 VIN OD VOUT2 2.5V 50mA LT6658-2.5 0.1µF VOUT1 2.5V 150mA VOUT1_F BYPASS 1µF 1µF VOUT1_S GND RLOAD1 OUTPUT VOLTAGE (V) Precision Dual Output 2.5V Reference and Supply 2.501 2.500 2.499 ILOAD1 = 150mA VOUT1 VOUT2 1µF 6658 TA01a 2.498 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 6658 TA01b Rev. C Document Feedback For more information www.analog.com 1 LT6658 ABSOLUTE MAXIMUM RATINGS (Note 1) Supply Voltages VIN, VIN1, VIN2 to GND............................. –0.3V to 38V Input Voltages OD to GND.............................................. –0.3V to 38V VOUT1_S , VOUT2_S, NR, BYPASS to GND... –0.3V to 6V Output Voltages VOUT1_F, VOUT2_F to GND.......................... –0.3V to 6V Input Current BYPASS............................................................ ±10mA Output Short-Circuit Duration........................... Indefinite Specified Temperature Range I-Grade.................................................–40°C to 85°C H-Grade.............................................. –40°C to 125°C Operating Junction Temperature Range.. –55°C to 150°C Storage Temperature Range (Note 2)...... –65°C to 150°C Lead Temperature (Soldering, 10 sec) (Note 3)............................................................. 300°C PIN CONFIGURATION TOP VIEW TOP VIEW GND GND BYPASS DNC NR GND VOUT2_S VOUT2_F 1 2 3 4 5 6 7 8 17 GND 16 15 14 13 12 11 10 9 DNC NC VIN VOUT1_S VOUT1_F VIN1 VIN2 OD MSE PACKAGE 16-LEAD PLASTIC MSOP TJMAX = 150°C, θJC = 10°C/W, θJA = 35°C/W DNC: CONNECTED INTERNALLY DO NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB GND 1 GND 2 BYPASS 3 DNC 4 NR 5 GND 6 VOUT2_S 7 VOUT2_F 8 16 DNC 15 NC 17 GND 14 VIN 13 VOUT1_S 12 VOUT1_F 11 VIN1 10 VIN2 9 OD DE PACKAGE 16-LEAD (4mm × 3mm) PLASTIC DFN TJMAX = 150°C,θJC = 5°C/W, θJA = 43°C/W DNC: CONNECTED INTERNALLY DO NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB Rev. C 2 For more information www.analog.com LT6658 ORDER INFORMATION TUBE TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED JUNCTION TEMPERATURE RANGE LT6658AIMSE-1.2#PBF LT6658AIMSE-1.2#TRPBF 665812 16-Lead Plastic MSOP –40°C to 85°C LT6658BIMSE-1.2#PBF LT6658BIMSE-1.2#TRPBF 665812 16-Lead Plastic MSOP –40°C to 85°C LT6658AHMSE-1.2#PBF LT6658AHMSE-1.2#TRPBF 665812 16-Lead Plastic MSOP –40°C to 125°C LT6658BHMSE-1.2#PBF LT6658BHMSE-1.2#TRPBF 665812 16-Lead Plastic MSOP –40°C to 125°C LT6658AIMSE-1.8#PBF LT6658AIMSE-1.8#TRPBF 665818 16-Lead Plastic MSOP –40°C to 85°C LT6658BIMSE-1.8#PBF LT6658BIMSE-1.8#TRPBF 665818 16-Lead Plastic MSOP –40°C to 85°C LT6658AHMSE-1.8#PBF LT6658AHMSE-1.8#TRPBF 665818 16-Lead Plastic MSOP –40°C to 125°C LT6658BHMSE-1.8#PBF LT6658BHMSE-1.8#TRPBF 665818 16-Lead Plastic MSOP –40°C to 125°C LT6658AIMSE-2.5#PBF LT6658AIMSE-2.5#TRPBF 665825 16-Lead Plastic MSOP –40°C to 85°C LT6658BIMSE-2.5#PBF LT6658BIMSE-2.5#TRPBF 665825 16-Lead Plastic MSOP –40°C to 85°C LT6658AHMSE-2.5#PBF LT6658AHMSE-2.5#TRPBF 665825 16-Lead Plastic MSOP –40°C to 125°C LT6658BHMSE-2.5#PBF LT6658BHMSE-2.5#TRPBF 665825 16-Lead Plastic MSOP –40°C to 125°C LT6658AIMSE-3#PBF LT6658AIMSE-3#TRPBF 66583 16-Lead Plastic MSOP –40°C to 85°C LT6658BIMSE-3#PBF LT6658BIMSE-3#TRPBF 66583 16-Lead Plastic MSOP –40°C to 85°C LT6658AHMSE-3#PBF LT6658AHMSE-3#TRPBF 66583 16-Lead Plastic MSOP –40°C to 125°C LT6658BHMSE-3#PBF LT6658BHMSE-3#TRPBF 66583 16-Lead Plastic MSOP –40°C to 125°C LT6658AIMSE-3.3#PBF LT6658AIMSE-3.3#TRPBF 665833 16-Lead Plastic MSOP –40°C to 85°C LT6658BIMSE-3.3#PBF LT6658BIMSE-3.3#TRPBF 665833 16-Lead Plastic MSOP –40°C to 85°C LT6658AHMSE-3.3#PBF LT6658AHMSE-3.3#TRPBF 665833 16-Lead Plastic MSOP –40°C to 125°C LT6658BHMSE-3.3#PBF LT6658BHMSE-3.3#TRPBF 665833 16-Lead Plastic MSOP –40°C to 125°C LT6658AIMSE-5#PBF LT6658AIMSE-5#TRPBF 66585 16-Lead Plastic MSOP –40°C to 85°C LT6658BIMSE-5#PBF LT6658BIMSE-5#TRPBF 66585 16-Lead Plastic MSOP –40°C to 85°C LT6658AHMSE-5#PBF LT6658AHMSE-5#TRPBF 66585 16-Lead Plastic MSOP –40°C to 125°C LT6658BHMSE-5#PBF LT6658BHMSE-5#TRPBF 66585 16-Lead Plastic MSOP –40°C to 125°C LT6658AIDE-1.2#PBF LT6658AIDE-1.2#TRPBF 65812 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658BIDE-1.2#PBF LT6658BIDE-1.2#TRPBF 65812 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658AHDE-1.2#PBF LT6658AHDE-1.2#TRPBF 65812 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658BHDE-1.2#PBF LT6658BHDE-1.2#TRPBF 65812 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658AIDE-1.8#PBF LT6658AIDE-1.8#TRPBF 65818 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658BIDE-1.8#PBF LT6658BIDE-1.8#TRPBF 65818 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658AHDE-1.8#PBF LT6658AHDE-1.8#TRPBF 65818 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658BHDE-1.8#PBF LT6658BHDE-1.8#TRPBF 65818 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658AIDE-2.5#PBF LT6658AIDE-2.5#TRPBF 65825 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658BIDE-2.5#PBF LT6658BIDE-2.5#TRPBF 65825 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658AHDE-2.5#PBF LT6658AHDE-2.5#TRPBF 65825 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658BHDE-2.5#PBF LT6658BHDE-2.5#TRPBF 65825 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658AIDE-3#PBF LT6658AIDE-3#TRPBF 66583 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658BIDE-3#PBF LT6658BIDE-3#TRPBF 66583 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658AHDE-3#PBF LT6658AHDE-3#TRPBF 66583 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C Rev. C For more information www.analog.com 3 LT6658 ORDER INFORMATION TUBE TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED JUNCTION TEMPERATURE RANGE LT6658BHDE-3#PBF LT6658BHDE-3#TRPBF 66583 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658AIDE-3.3#PBF LT6658AIDE-3.3#TRPBF 65833 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658BIDE-3.3#PBF LT6658BIDE-3.3#TRPBF 65833 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658AHDE-3.3#PBF LT6658AHDE-3.3#TRPBF 65833 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658BHDE-3.3#PBF LT6658BHDE-3.3#TRPBF 65833 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658AIDE-5#PBF LT6658AIDE-5#TRPBF 66585 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658BIDE-5#PBF LT6658BIDE-5#TRPBF 66585 16-Lead (4mm × 3mm) Plastic DFN –40°C to 85°C LT6658AHDE-5#PBF LT6658AHDE-5#TRPBF 66585 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C LT6658BHDE-5#PBF LT6658BHDE-5#TRPBF 66585 16-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C *The temperature grade is identified by a label on the shipping container. Consult ADI Marketing for parts specified with wider operating temperature ranges. Parts ending with PBF are RoHS and WEEE compliant. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. AVAILABLE OPTIONS OUTPUT VOLTAGE INITIAL ACCURACY TEMPERATURE COEFFICIENT ORDER PART NUMBER ** SPECIFIED JUNCTION TEMPERATURE RANGE 1.200V 0.05% 10ppm/°C LT6658AIMSE-1.2 –40°C to 85°C 1.800V 0.1% 20ppm/°C LT6658BIMSE-1.2 –40°C to 85°C 0.05% 10ppm/°C LT6658AHMSE-1.2 –40°C to 125°C 0.1% 20ppm/°C LT6658BHMSE-1.2 –40°C to 125°C 0.05% 10ppm/°C LT6658AIDE-1.2 –40°C to 85°C 0.1% 20ppm/°C LT6658BIDE-1.2 –40°C to 85°C 0.05% 10ppm/°C LT6658AHDE-1.2 –40°C to 125°C 0.1% 20ppm/°C LT6658BHDE-1.2 –40°C to 125°C 0.05% 10ppm/°C LT6658AIMSE-1.8 –40°C to 85°C 0.1% 20ppm/°C LT6658BIMSE-1.8 –40°C to 85°C 0.05% 10ppm/°C LT6658AHMSE-1.8 –40°C to 125°C 0.1% 20ppm/°C LT6658BHMSE-1.8 –40°C to 125°C 0.05% 10ppm/°C LT6658AIDE-1.8 –40°C to 85°C 0.1% 20ppm/°C LT6658BIDE-1.8 –40°C to 85°C 0.05% 10ppm/°C LT6658AHDE-1.8 –40°C to 125°C 0.1% 20ppm/°C LT6658BHDE-1.8 –40°C to 125°C Rev. C 4 For more information www.analog.com LT6658 AVAILABLE OPTIONS ORDER PART NUMBER ** 0.05% 10ppm/°C LT6658AIMSE-2.5 –40°C to 85°C 0.1% 20ppm/°C LT6658BIMSE-2.5 –40°C to 85°C 0.05% 10ppm/°C LT6658AHMSE-2.5 –40°C to 125°C 0.1% 20ppm/°C LT6658BHMSE-2.5 –40°C to 125°C 0.05% 10ppm/°C LT6658AIDE-2.5 –40°C to 85°C INITIAL ACCURACY 2.500V 3.000V 3.300V 5.000V SPECIFIED JUNCTION TEMPERATURE RANGE TEMPERATURE COEFFICIENT OUTPUT VOLTAGE 0.1% 20ppm/°C LT6658BIDE-2.5 –40°C to 85°C 0.05% 10ppm/°C LT6658AHDE-2.5 –40°C to 125°C 0.1% 20ppm/°C LT6658BHDE-2.5 –40°C to 125°C 0.05% 10ppm/°C LT6658AIMSE-3 –40°C to 85°C 0.1% 20ppm/°C LT6658BIMSE-3 –40°C to 85°C 0.05% 10ppm/°C LT6658AHMSE-3 –40°C to 125°C 0.1% 20ppm/°C LT6658BHMSE-3 –40°C to 125°C 0.05% 10ppm/°C LT6658AIDE-3 –40°C to 85°C 0.1% 20ppm/°C LT6658BIDE-3 –40°C to 85°C 0.05% 10ppm/°C LT6658AHDE-3 –40°C to 125°C 0.1% 20ppm/°C LT6658BHDE-3 –40°C to 125°C 0.05% 10ppm/°C LT6658AIMSE-3.3 –40°C to 85°C 0.1% 20ppm/°C LT6658BIMSE-3.3 –40°C to 85°C 0.05% 10ppm/°C LT6658AHMSE-3.3 –40°C to 125°C 0.1% 20ppm/°C LT6658BHMSE-3.3 –40°C to 125°C 0.05% 10ppm/°C LT6658AIDE-3.3 –40°C to 85°C 0.1% 20ppm/°C LT6658BIDE-3.3 –40°C to 85°C 0.05% 10ppm/°C LT6658AHDE-3.3 –40°C to 125°C 0.1% 20ppm/°C LT6658BHDE-3.3 –40°C to 125°C 0.05% 10ppm/°C LT6658AIMSE-5 –40°C to 85°C 0.1% 20ppm/°C LT6658BIMSE-5 –40°C to 85°C 0.05% 10ppm/°C LT6658AHMSE-5 –40°C to 125°C 0.1% 20ppm/°C LT6658BHMSE-5 –40°C to 125°C 0.05% 10ppm/°C LT6658AIDE-5 –40°C to 85°C 0.1% 20ppm/°C LT6658BIDE-5 –40°C to 85°C 0.05% 10ppm/°C LT6658AHDE-5 –40°C to 125°C 0.1% 20ppm/°C LT6658BHDE-5 –40°C to 125°C Rev. C For more information www.analog.com 5 LT6658 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full specified temperature range, otherwise specifications are at TA = 25°C. VIN = VIN1 = VIN2 = VOUT1,2_F + 2.5V, COUT1,2 = 1.3µF, ILOAD = 0, unless otherwise noted. PARAMETER CONDITIONS Output Voltage Accuracy LT6658A LT6658B LT6658AI LT6658BI LT6658AH LT6658BH l l l l Output Voltage Temperature Coefficient (Note 4) LT6658A LT6658B l l Line Regulation (Note 5) LT6658-1.2, LT6658-1.8 4.5V ≤ VIN ≤ 36V, VIN = VIN1 = VIN2 l LT6658-2.5, LT6658-3.3, LT6658-5 VOUT + 2.5V ≤ VIN ≤ 36V, VIN = VIN1 = VIN2 l Load Regulation (Note 5) MIN Output 1 Sourcing, ΔILOAD = 0mA to 150mA TYP –0.05 –0.1 –0.175 –0.35 –0.215 –0.43 2.0 5.0 6.0 ppm/V ppm/V 1.4 4.5 5 ppm/V ppm/V 0.25 1.25 2.0 µV/mA µV/mA 0.25 3.25 3.75 µV/mA µV/mA 0.25 3.2 3.75 µV/mA µV/mA 0.25 3.2 3.75 µV/mA µV/mA 3.5 4.0 4.5 V V 4.2 4.5 5.0 V V 4.5 4.8 5.3 V V 5.2 7.0 7.5 V V l VIN Minimum Voltage VIN1 Dropout Voltage VIN2 Dropout Voltage Supply Current % % % % % % ppm/°C ppm/°C l Output 2 Sinking, ΔILOAD = 0mA to 20mA 0.05 0.1 0.175 0.35 0.215 0.43 10 20 l Output 1 Sinking, ΔILOAD = 0mA to 20mA UNITS 3 10 l Output 2 Sourcing, ΔILOAD = 0mA to 50mA (Note 6) MAX LT6658-1.2, LT6658-1.8, LT6658-2.5 ΔVOUT = 0.1%, IOUT = 0mA, VIN1 = VIN2 = 4.5V l LT6658-3 ΔVOUT = 0.1%, IOUT = 0mA, VIN1 = VIN2 = 5.5V l LT6658-3.3 ΔVOUT = 0.1%, IOUT = 0mA, VIN1 = VIN2 = 5.8V l LT6658-5 ΔVOUT = 0.1%, IOUT = 0mA, VIN1 = VIN2 = 7.5V l LT6658-1.2, LT6658-1.8 ΔVOUT1 = 0.1%, IOUT1 = 0mA, VIN = VIN2 = VOUT + 4.5V ΔVOUT1 = 0.1%, IOUT1 = 150mA, VIN = VIN2 = VOUT + 4.5V l 2.0 2.3 2.3 2.5 V V LT6658-2.5, LT6658-3, LT6658-3.3, LT6658-5 ΔVOUT1 = 0.1%, IOUT1 = 0mA, VIN = VIN2 = VOUT + 2.5V ΔVOUT1 = 0.1%, IOUT1 = 150mA, VIN = VIN2 = VOUT + 2.5V l 2.0 2.2 2.3 2.5 V V LT6658-1.2, LT6658-1.8 ΔVOUT2 = 0.1%, IOUT2 = 0mA, VIN = VIN1 = VOUT + 4.5V ΔVOUT2 = 0.1%, IOUT2 = 50mA, VIN = VIN1 = VOUT + 4.5V l 1.8 2.0 2.2 2.5 V V LT6658-2.5, LT6658-3, LT6658-3.3, LT6658-5 ΔVOUT2 = 0.1%, IOUT2 = 0mA, VIN = VIN1 = VOUT + 2.5V ΔVOUT2 = 0.1%, IOUT2 = 50mA, VIN = VIN1 = VOUT + 2.5V l 1.8 2.0 2.2 2.5 V V LT6658-1.2, VOD = 2.0V, No Load l 2.0 3.2 mA LT6658-1.8, VOD = 2.0V, No Load l 2.5 3.6 mA LT6658-2.5, LT6658-3, LT6658-3.3, LT6658-5, VOD = 2.0V, No Load l 1.9 3.0 mA VOD = 0.8V, No Load LT6658-1.2 LT6658-1.8 LT6658-2.5 LT6658-3 LT6658-3.3 LT6658-5 l l l l l l 0.7 1.3 1.0 1.2 1.3 1.7 1.1 1.8 1.5 1.8 2 2.5 mA mA mA mA mA mA Rev. C 6 For more information www.analog.com LT6658 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = VIN1 = VIN2 = VOUT1,2_F + 2.5V, COUT1,2 = 1.3µF, ILOAD = 0, unless otherwise noted. PARAMETER CONDITIONS Output Short-Circuit Current Short VOUT1_F to 400mV (Note 11) Short VOUT2_F to 400mV (Note 11) l l MIN TYP 170 65 270 120 mA mA 0.8 1.0 1.5 1.6 1.7 2.2 ppmP–P ppmP–P ppmP–P ppmP–P ppmP–P ppmP–P 0.5 2 8 ppmRMS ppmRMS nV/√Hz Output Noise Voltage (Note 7) 0.1Hz ≤ f ≤ 10Hz LT6658-1.2 LT6658-1.8 LT6658-2.5 LT6658-3 LT6658-3.3 LT6658-5 10Hz ≤ f ≤ 1kHz, COUT = 1µF, CNR = 10µF, ILOAD = Full Current (Note 10) 10Hz ≤ f ≤ 1kHz, COUT = 1µF, CNR = OPEN, ILOAD = Full Current (Note 10) Frequency = 10kHz, COUT1 = 1µF, CNR = 10µF, ILOAD = Full Current (Note 10) MAX UNITS Output Voltage Tracking Tracking = Output 1 – Output 2 0.9 µV/°C VOUT1_S, VOUT2_S Pin Current Unity Gain 135 nA OD Threshold Voltage Logic High Input Voltage Logic Low Input Voltage l l OD Pin Current VOD = 0V VOD = 36V l l Ripple Rejection VIN1 = VOUT1 + 3V, VRIPPLE = 0.5VP–P, fRIPPLE = 120Hz, ILOAD = 150mA, COUT1 = 1µF, CNR = 10µF VIN2 = VOUT2 + 3V, VRIPPLE = 0.5VP–P, fRIPPLE = 120Hz, ILOAD = 50mA, COUT2 = 1µF, CNR = 10µF 107 dB 107 dB 0.1% Settling, CLOAD  =  1μF 160 μs 120 ppm/√kHr 30 45 ppm ppm Turn-On Time Long Term Drift (Note 8) Thermal Hysteresis (Note 9) ∆T = –40°C to 85°C ∆T = –40°C to 125°C Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Thermal hysteresis can occur during storage at extreme temperatures. Note 3: The stated temperature is typical for soldering of the leads during manual rework. For detailed IR reflow recommendations, refer to the Applications Information section. Note 4: Temperature coefficient is measured by dividing the maximum change in output voltage by the specified temperature range. Note 5: Line and load regulation are measured on a pulse basis for specified input voltage or load current ranges. Output changes due to die temperature change must be taken into account separately. Note 6: VOUT2 load regulation specification is limited by practical automated test resolution. Please refer to the Typical Performance Characteristics section for more information regarding actual typical performance. Note 7: Peak-to-peak noise is measured with a 1-pole highpass filter at 0.1Hz and 2-pole lowpass filter at 10Hz. The unit is enclosed in a still-air environment to eliminate thermocouple effects on the leads. The test 2 30 0.3 0.8 V V 45 1.5 μA μA time is 10 seconds. RMS noise is measured on a spectrum analyzer in a shielded environment where the intrinsic noise of the instrument is removed to determine the actual noise of the device. Note 8: Long-term stability typically has a logarithmic characteristic and therefore, changes after 1000 hours tend to be much smaller than before that time. Total drift in the second thousand hours is normally less than one third that of the first thousand hours with a continuing trend toward reduced drift with time. Long-term stability will also be affected by differential stresses between the IC and the board material created during board assembly. Note 9: Hysteresis in output voltage is created by package stress that differs depending on whether the IC was previously at a higher or lower temperature. Output voltage is always measured at 25°C, but the IC is cycled to the hot or cold temperature limit before successive measurements. Hysteresis measures the maximum output change for the averages of three hot or cold temperature cycles. For instruments that are stored at well controlled temperatures (within 20 or 30 degrees of operational temperature), it’s usually not a dominant error source. Typical hysteresis is the worst-case of 25°C to cold to 25°C or 25°C to hot to 25°C, preconditioned by one thermal cycle. Note 10: The full current for ILOAD is 150mA and 50mA for Output 1 and Output 2, respectively. Note 11: When the output voltage is less than 450mV, the output current may foldback to less than the rated output current. Once the output is released, the rated output current will be available. Rev. C For more information www.analog.com 7 LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 1.2V VOUT1 and VOUT2 Output 1.2V VOUT1 Output Voltage 1.2V VOUT2 Output Voltage Voltage vs Temperature with Temperature Drift Temperature Drift 150mA Load on VOUT1 1.202 1.201 1.200 1.199 1.198 –50 –25 0 1.201 1.200 1.199 1.198 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) 1.202 THREE TYPICAL PARTS OUTPUT VOLTAGE (V) THREE TYPICAL PARTS OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 1.202 0 60 60 50 40 30 20 10 0 –10 0.1 1 10 100 OUTPUT CURRENT (mA) 0 25 50 75 100 125 150 TEMPERATURE (°C) 40 125°C 25°C –45°C 50 40 30 20 10 0 –10 0.1 500 1.2V VOUT1 Load Regulation, Sinking 1 10 OUTPUT CURRENT (mA) 125°C 25°C –45°C 30 20 10 0 –10 0.1 100 6658 G04 1 10 OUTPUT CURRENT (mA) 6658 G05 1.2V VOUT2 Load Regulation, Sinking 100 6658 G06 1.2V Line Regulation VOUT1 40 1.2V Line Regulation VOUT2 1.202 1.202 1.201 1.201 20 10 0 125°C 25°C –45°C –10 –20 0.1 1 10 OUTPUT CURRENT (mA) 100 OUTPUT VOLTAGE (V) 30 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE CHANGE (ppm) VOUT1 VOUT2 6658 G03 OUTPUT VOLTAGE CHANGE (ppm) OUTPUT VOLTAGE CHANGE (ppm) OUTPUT VOLTAGE CHANGE (ppm) 70 1.199 1.2V VOUT2 Load Regulation, Sourcing 125°C 25°C –45°C 80 1.200 6658 G02 1.2V VOUT1 Load Regulation, Sourcing 90 1.201 1.198 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) 6658 G01 ILOAD1 = 150mA 1.200 1.199 1.198 125°C 25°C –45°C 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 6658 G07 40 6658 G08 1.200 1.199 1.198 125°C 25°C –45°C 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 40 6658 G09 Rev. C 8 For more information www.analog.com LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 1.2V VOUT1 Power Supply Rejection Ratio vs Frequency 1.2V Supply Current vs Input Voltage 2.5 120 80 PSRR (dB) PSRR (dB) INPUT CURRENT (mA) 1.0 60 40 0 125°C 25°C –45°C 0 4 8 0 0.01 20 CNR = 1µF CNR = 10µF 0.1 1 10 FREQUENCY (kHz) 100 6658 G10 120 60 40 20 20 0 0.01 ILOAD1 = 0mA ILOAD1 = 150mA 0.1 1 10 FREQUENCY (kHz) 100 0 0.01 1000 ILOAD = 0mA ILOAD = 50mA 0.1 1 10 FREQUENCY (kHz) 100 6658 G13 1 0.001 0.0001 0.01 COUT1 = 1µF COUT1 = 50µF 0.1 1 10 FREQUENCY (kHz) 100 1000 IOUT1 = 10mA 0.01 0.001 0.0001 0.01 1000 COUT1 = 1µF COUT1 = 50µF 0.1 1 10 FREQUENCY (kHz) 100 1.2V VOUT2 AC Output Impedance 50mA Load 1 IOUT1 = 1mA 0.1 0.01 0.001 0.0001 0.01 COUT2 = 1µF COUT2 = 50µF 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G17 6658 G16 1000 6658 G15 OUTPUT IMPEDANCE (Ω) OUTPUT IMPEDANCE (Ω) 0.01 1000 0.1 1.2V VOUT2 AC Output Impedance 1mA Load IOUT1 = 150mA 0.1 100 6658 G14 1.2V VOUT1 AC Output Impedance 150mA Load 1 1 OUTPUT IMPEDANCE (Ω) PSRR (dB) PSRR (dB) 80 40 1 10 FREQUENCY (kHz) 1.2V VOUT1 AC Output Impedance 10mA Load VIN = VIN1 = VIN2 = 5V CNR = 10µF COUT2 = 1µF 100 80 60 0.1 6658 G12 1.2V VOUT2 Power Supply Rejection Ratio vs Frequency VIN = VIN1 = VIN2 = 5V CNR = 10µF COUT1 = 1µF 100 0 0.01 1000 CNR = 1µF CNR = 10µF 6658 G11 1.2V VOUT1 Power Supply Rejection Ratio vs Frequency 120 60 40 20 12 16 20 24 28 32 36 40 INPUT VOLTAGE (V) VIN = VIN1 = VIN2 = 5V COUT2 = 1µF ILOAD = 0A 100 80 1.5 0.5 OUTPUT IMPEDANCE (Ω) 120 VIN = VIN1 = VIN2 = 5V COUT1 = 1µF ILOAD = 0A 100 2.0 1.2V VOUT2 Power Supply Rejection Ratio vs Frequency IOUT1 = 50mA 0.1 0.01 0.001 0.0001 0.01 COUT2 = 1µF COUT2 = 50µF 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G18 Rev. C For more information www.analog.com 9 LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 2V/DIV VBYPASS VOUT1 2V/DIV VOUT2 2V/DIV CNR = OPEN COUT1 = 1µF COUT2 = 1µF 6658 G19 50µs/DIV VOUT1 CHANNEL TO CHANNEL ISOLATION (dB) VIN 5V/DIV 1.2V Channel to Channel Load Isolation VOUT1 to VOUT2 VOUT2 CHANNEL TO CHANNEL ISOLATION (dB) 1.2V Channel to Channel Load Isolation VOUT2 to VOUT1 1.2V Turn-On Characteristic 140 50mVRMS SIGNAL ON VOUT2 120 100 80 60 40 20 0 0.001 ILOAD2 = 50mA ILOAD2 = 0mA 0.1 1 10 FREQUENCY (kHz) 100 1000 140 50mVRMS SIGNAL ON VOUT1 120 100 80 60 40 20 0 0.001 ILOAD1 = 150mA ILOAD1 = 0mA 0.1 1 10 FREQUENCY (kHz) 100 6658 G20 1.2V VOUT1 Output Noise 0.1Hz to 10Hz 1000 6658 G21 1.2V VOUT2 Output Noise 0.1Hz to 10Hz 1.2V VOUT1 Output Voltage Noise Spectrum ILOAD = 0mA 250 1µV/DIV NOISE VOLTAGE (nV/√Hz) COUT1 = 1µF 1µV/DIV 6658 G22 1s/DIV 6658 G23 1s/DIV 200 150 100 CNR = OPEN 50 CNR = 10µF 0 0.01 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G24 1.2V VOUT2 Output Voltage Noise Spectrum ILOAD = 0mA 1.2V Line Transient Response 250 NOISE VOLTAGE (nV/√Hz) COUT2 = 1µF 500mV/DIV 200 2mV/DIV 2mV/DIV 150 100 2mV/DIV CNR = OPEN VIN 500mV/DIV VBYPASS 2mV/DIV VOUT1 2mV/DIV VOUT2 2mV/DIV CNR = OPEN COUT1 = COUT2 = 1µF 50 1.2V Line Transient Response VIN = 4.5V TO 5V ILOAD = 0mA 50µs/DIV 6658 G26 VIN VBYPASS VOUT1 VOUT2 CNR = 1µF COUT1 = COUT2 = 1µF 50µs/DIV VIN = 4.5V to 5V ILOAD = 0mA 6658 G27 CNR = 10µF 0 0.01 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G25 10 Rev. C For more information www.analog.com LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 1.2V Line Transient Response 1.2V VOUT1 Current Limit 2mV/DIV VOUT1 2mV/DIV VOUT2 2mV/DIV CNR = 1µF COUT1 = COUT2 = 1µF VIN = 4.5V TO 5V ILOAD = 50mA 50µs/DIV CURRENT LIMIT (mA) VBYPASS 140 350 120 300 CURRENT LIMIT (mA) VIN 500mV/DIV 400 250 200 150 100 100 6658 G28 50 0 –50 –25 80 60 40 20 VIN = 5V VIN = 10V 0 1.2V VOUT2 Current Limit 0 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) VIN = 5V VIN = 10V 0 25 50 75 100 125 150 TEMPERATURE (°C) 6658 G30 6658 G29 2.5V VOUT1 Output Voltage Temperature Drift 2.5V VOUT2 Output Voltage Temperature Drift 2.502 OUTPUT VOLTAGE (V) 2.500 2.499 2.498 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 2.502 THREE TYPICAL PARTS 2.501 OUTPUT VOLTAGE (V) THREE TYPICAL PARTS 2.501 2.500 2.499 2.498 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 20 OUTPUT VOLTAGE CHANGE (ppm) 20 15 10 5 0 –5 10 100 OUTPUT CURRENT (mA) 2.499 2.498 –50 –25 500 6658 G34 0 25 50 75 100 125 150 TEMPERATURE (°C) 6658 G33 15 10 5 0 1 VOUT1 VOUT2 2.5V VOUT1 Load Regulation, Sinking 125°C 25°C –45°C 15 –5 1 2.500 2.5V VOUT2 Load Regulation, Sourcing 125°C 25°C –45°C 25 2.501 OUTPUT VOLTAGE CHANGE (ppm) 2.5V VOUT1 Load Regulation, Sourcing 30 ILOAD1 = 150mA 6658 G32 6658 G31 OUTPUT VOLTAGE CHANGE (ppm) OUTPUT VOLTAGE (V) 2.502 2.5V VOUT1 and VOUT2 Output Voltage vs Temperature with 150mA Load on VOUT1 10 LOAD CURRENT (mA) 100 6658 G35 10 5 0 –5 125°C 25°C –45°C 1 10 OUTPUT CURRENT (mA) 100 6658 G36 Rev. C For more information www.analog.com 11 LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 2.5V VOUT2 Load Regulation, Sinking 2.5V Line Regulation VOUT1 10 5 0 2.502 2.501 2.501 2.500 2.499 2.498 125°C 25°C –40°C 2.497 –5 1 10 OUTPUT CURRENT (mA) 100 2.5V Line Regulation VOUT2 2.502 OUTPUT VOLTAGE (V) 125°C 25°C –45°C OUTPUT VOLTAGE (V) OUTPUT VOLTAGE CHANGE (ppm) 15 2.496 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 6658 G37 40 2.500 2.499 2.498 2.497 2.496 40 35 1.5 1.0 0.5 125°C 25°C –40°C 5 0 2.4985 2.4990 2.4995 2.5000 2.5005 2.5010 2.5015 VOUT1 (V) 0 0 4 8 1.0 0.8 0.6 0.4 125°C 25°C –40°C 0.2 0 12 16 20 24 28 32 36 40 INPUT VOLTAGE (V) 6658 G40 0 4 8 12 16 20 24 28 32 36 40 INPUT VOLTAGE (V) 6658 G41 2.5V Minimum VIN to VOUT1 Differential, Sourcing 6658 G42 2.5V Minimum VIN to VOUT2 Differential, Sourcing 200 40 1.2 2.0 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) NUMBER OF UNITS 10 15 20 25 30 INPUT VOLTAGE (V) 1.4 35 15 10 2.5V Output Disable (OD) Low Supply Current vs Input Voltage 2.5 20 5 6658 G39 2.5V Supply Current vs Input Voltage 25 0 6658 G38 2.5V Output Accuracy Histogram 30 125°C 25°C –40°C 2.5V VOUT1 Power Supply Rejection Ratio vs Frequency 100 120 VIN = VIN1 = VIN2 = 6V 100 10 1 0.1 1.1 125°C 25°C –40°C 1.4 1.6 1.9 INPUT–OUTPUT VOLTAGE (V) 2.1 10 80 PSRR (dB) OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 100 1 0.1 1.1 60 40 125°C 25°C –40°C 1.3 1.5 1.7 1.9 INPUT–OUTPUT VOLTAGE (V) 6658 G43 2.1 6658 G44 COUT1 = 1µF ILOAD = 0A 20 0 0.01 CNR = 1µF CNR = 10µF 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G45 Rev. C 12 For more information www.analog.com LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 2.5V VOUT2 Power Supply Rejection Ratio vs Frequency 120 VIN = VIN1 = VIN2 = 6V 120 VIN = VIN1 = VIN2 = 6V 100 80 80 80 60 40 COUT2 = 1µF ILOAD = 0A 20 0 0.01 20 CNR = 1µF CNR = 10µF 0.1 1 10 FREQUENCY (kHz) 100 1000 0.1 1 10 FREQUENCY (kHz) 100 6658 G46 0.1 0.1 0.1 1 10 FREQUENCY (kHz) 100 1000 1000 ILOAD = 0A ILOAD = 50mA 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G48 2.5V VOUT2 AC Output Impedance 1mA Load 10 0.01 0.001 IOUT1 = 150mA COUT1 = 1µF COUT1 = 50µF 0.0001 0.01 0.1 1 10 FREQUENCY (kHz) 100 6658 G49 1000 1 0.1 0.01 0.001 0.0001 0.01 IOUT2 = 1mA COUT2 =1µF COUT2 = 50µF 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G51 6658 G50 2.5V VOUT2 AC Output Impedance 50mA Load 2.5V Turn-On Characteristic 1 5V/DIV OUTPUT IMPEDANCE (Ω) 0.0001 0.01 COUT1 = 1µF COUT1 = 50µF OUTPUT IMPEDANCE (Ω) 1 IOUT1 = 10mA 0 0.01 2.5V VOUT1 AC Output Impedance 150mA Load 1 0.001 CNR = 10µF COUT1 = 1µF 6658 G47 2.5V VOUT1 AC Output Impedance 10mA Load 0.01 60 20 ILOAD1 = 0A ILOAD1 = 150mA 0 0.01 VIN = VIN1 = VIN2 = 6V 40 CNR = 10µF COUT1 = 1µF OUTPUT IMPEDANCE (Ω) 60 PSRR (dB) 100 40 OUTPUT IMPEDANCE (Ω) 2.5V VOUT2 Power Supply Rejection Ratio vs Frequency 100 PSRR (dB) PSRR (dB) 120 2.5V VOUT1 Power Supply Rejection Ratio vs Frequency 0.1 2V/DIV 0.01 0.001 0.0001 0.01 VOUT1 2V/DIV VOUT2 COUT2 = 1µF COUT2 = 50µF 1 10 FREQUENCY (kHz) 100 VBYPASS 2V/DIV IOUT2 = 50mA 0.1 VIN CNR = OPEN COUT1 = 1µF COUT2 = 1µF 50µs/DIV 6658 G53 1000 6658 G52 Rev. C For more information www.analog.com 13 LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 140 50mVRMS SIGNAL ON VOUT1 120 100 80 60 40 20 0 0.001 ILOAD1 = 150mA ILOAD1 = 0mA 0.1 1 10 FREQUENCY (kHz) 100 140 50mVRMS SIGNAL ON VOUT2 120 100 80 60 40 20 0 0.001 1000 6658 G54 100 20 COUT2 = 10µF / CNR=10µF COUT2 = 50µF / CNR = 10µF 80 COUT2 = 1µF / CNR = OPEN 60 40 VIN = VIN2 = 7V 20 V = 6VDC + 700mV IN1 RMS ILOAD1 = ILOAD2 = 0A, TA = 25°C 0 0.01 0.1 1 10 FREQUENCY (kHz) 1000 150 125 100 75 50 VIN = VIN1 = 7V 20 VIN2 = 6VDC + 700mVRMS ILOAD1 = ILOAD2 = 0A, TA = 25°C 0 0.01 0.1 1 10 FREQUENCY (kHz) 25 50 75 100 125 150 TEMPERATURE (°C) 100 IOUT1 12 10 VOUT2 8 100µV/DIV 6 4 1 10 100 VOUT1 LOAD CURRENT (mA) CNR = 0.1µF COUT1 = 1µF COUT2 = 1µF 500 10µs/DIV 6658 G59 6658 G58 2.5V Tracking (VOUT1 – VOUT2) vs Temperature 2.5V OD Pin Current vs OD Pin Input Voltage 250 THREE TYPICAL PARTS 150 10 1 0.1 0 1 2 3 OD PIN INPUT VOLTAGE (V) 50 0 –50 –100 –200 4 6658 G61 6658 G60 100 –150 125°C 25°C –40°C 25 14 40 10mA VOUT1 - VOUT2 (µV) 175 COUT1 = 10µF / CNR =10µF 60 200 200 COUT1 = 50µF / CNR = 10µF 80 150mA 14 0 100 COUT1 = 1µF / CNR = OPEN 100 2.5V Channel to Channel Isolation, Time Domain 100 0 120 6658 G56 THREE TYPICAL PARTS 0 –50 –25 140 2 OD PIN INPUT CURRENT (µA) VOUT1_S PIN CURRENT (nA) 100 2.5V Channel to Channel Isolation VIN2 to VOUT1 16 2.5V VOUT1_S Pin Input Current vs Temperature 225 1 10 FREQUENCY (kHz) 160 2.5V Channel to Channel Load Regulation (Effects of Heating Removed) 6658 G57 250 0.1 18 VOUT2 VOLTAGE CHANGE (ppm) VOUT2 CHANNEL TO CHANNEL ISOLATION (dB) 120 ILOAD2 = 50mA ILOAD2 = 0mA 6658 G55 2.5V Channel to Channel Isolation VIN1 to VOUT2 140 VOUT1 CHANNEL TO CHANNEL ISOLATION (dB) 2.5V Channel to Channel Load Isolation VOUT2 to VOUT1 VOUT1 CHANNEL TO CHANNEL ISOLATION (dB) VOUT2 CHANNEL TO CHANNEL ISOLATION (dB) 2.5V Channel to Channel Load Isolation VOUT1 to VOUT2 –250 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 6658 G62 Rev. C For more information www.analog.com LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 2.5V Tracking (VOUT1 – VOUT2) vs Input Voltage 160 90 120 60 80 VOUT1 – VOUT2 (µV) VOUT1 – VOUT2 (µV) 200 THREE TYPICAL PARTS 120 30 0 –30 –60 0 –80 –120 –160 8 12 16 20 24 VIN (V) 28 32 36 OUTPUT NOISE (2µV/DIV) –40 –120 4 THREE TYPICAL PARTS 40 –90 –150 –200 0.01 2.5V VOUT2 Output Noise 0.1Hz to 10Hz NOISE VOLTAGE (nV/√Hz) 300 6658 G66 1s/DIV 0.1 1 10 100 VOUT1 LOAD CURRENT (mA) 1k 6658 G64 2.5V VOUT1 Output Voltage Noise Spectrum ILOAD = 0mA 240 CNR = OPEN 180 120 60 CNR = 10µF 0.1 1 10 FREQUENCY (kHz) 100 1000 2.5V VOUT2 Output Voltage Noise Spectrum ILOAD = 0mA 300 COUT1 = 1µF 0 0.01 COUT2 = 1µF 240 CNR = OPEN 180 120 60 CNR = 10µF 0 0.01 0.1 6658 G67 300 COUT1 = 1µF 200 CNR = OPEN 150 100 CNR = 10µF 50 0 0.01 2.5V VOUT2 Output Voltage Noise Spectrum ILOAD = 50mA 0.1 1 10 FREQUENCY (kHz) 200 CNR = OPEN 150 100 CNR = 10µF 1000 0 0.01 0.1 1 10 FREQUENCY (kHz) 100 1000 2.5V VOUT1 Integrated Noise ILOAD = 0mA 60 50 100 70 COUT2 = 1µF 250 NOISE VOLTAGE (nV/√Hz) NOISE VOLTAGE (nV/√Hz) 250 1 10 FREQUENCY (kHz) 6658 G68 INTEGRATED NOISE (µVRMS) 300 2.5V VOUT1 Output Voltage Noise Spectrum ILOAD = 150mA 6658 G65 1s/DIV 6658 G63 OUTPUT NOISE (2µV/DIV) 2.5V VOUT1 Output Noise 0.1Hz to 10Hz NOISE VOLTAGE (nV/√Hz) 150 2.5V Tracking (VOUT1 – VOUT2) vs VOUT1 Load Current CNR = 0PEN CNR = 10µF COUT1 = 1µF 50 ILOAD = 0mA 40 30 20 10 100 6658 G69 1000 6658 G70 0 0.01 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G71 Rev. C For more information www.analog.com 15 LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 70 60 CNR = OPEN CNR =10µF 60 COUT2 = 1µF 50 ILOAD = 0mA INTEGRATED NOISE (µVRMS) INTEGRATED NOISE (µVRMS) 2.5V VOUT1 Integrated Noise ILOAD = 150mA 40 30 20 10 0 0.01 0.1 1 10 FREQUENCY (kHz) 100 50 40 COUT1 = 1µF ILOAD = 150mA 30 20 10 0.1 6658 G72 500mV/DIV VBYPASS 2mV/DIV VOUT1 2mV/DIV 2mV/DIV VOUT2 2mV/DIV 2mV/DIV CNR = OPEN COUT1 = COUT2 = 1µF VIN = 5V to 5.5V ILOAD = 0mA 50µs/DIV 40 30 20 10 VBYPASS VOUT2 VIN = 5V to 5.5V ILOAD = 0mA CNR = 1µF COUT1 = COUT2 = 1µF 6658 G76 450 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 6658 G78 100 80 60 40 350 300 250 200 150 100 VIN = 5V VIN = 10V 20 0 –50 –25 IOUT1 IOUT2 400 120 CURRENT LIMIT (mA) CURRENT LIMIT (mA) VIN = 5V VIN = 7.5V VIN = 10V 6658 G77 Current Limit vs Supply Voltage 140 50 VIN = 5V to 5.5V ILOAD = 50mA 50µs/DIV 450 150 VOUT2 2mV/DIV 50µs/DIV 400 VOUT1 2mV/DIV 500 200 1000 VBYPASS VOUT1 2.5V VOUT2 Current Limit 250 100 VIN 2mV/DIV 160 300 1 10 FREQUENCY (kHz) 2.5V Line Transient Response 500mV/DIV 6658 G75 350 0.1 6658 G74 500 100 COUT2 = 1µF ILOAD = 50mA 0 0.01 1000 VIN CNR = 1µF COUT1 = COUT2 = 1µF 2.5V VOUT1 Current Limit CURRENT LIMIT (mA) 100 50 2.5V Line Transient Response VIN 2mV/DIV 1 10 FREQUENCY (kHz) CNR = OPEN CNR = 10µF 6658 G73 2.5V Line Transient Response 500mV/DIV 60 CNR = OPEN CNR = 10µF 0 0.01 1000 2.5V VOUT2 Integrated Noise ILOAD = 50mA INTEGRATED NOISE (µVRMS) 2.5V VOUT2 Integrated Noise ILOAD = 0mA 0 25 50 75 100 125 150 TEMPERATURE (°C) 6658 G79 50 0 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 35 40 6658 G80 Rev. C 16 For more information www.analog.com LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 5V VOUT1 and VOUT2 Output 5V VOUT1 Output Voltage 5V VOUT2 Output Voltage Voltage vs Temperature with Temperature Drift Temperature Drift 150mA Load on VOUT1 5.006 THREE TYPICAL PARTS 5.002 5.000 4.998 4.996 5.002 5.000 4.998 4.996 4.994 –50 –25 0 0 5 15 OUTPUT VOLTAGE CHANGE (ppm) OUTPUT VOLTAGE CHANGE (ppm) 20 0 –5 –10 –15 –20 125°C 25°C –45°C 1 10 100 OUTPUT CURRENT (mA) 40 125°C 25°C –45°C 10 5 0 –5 –10 –15 –20 0.1 500 1 10 OUTPUT CURRENT (mA) –10 –20 0.1 10 0 100 1 10 OUTPUT CURRENT (mA) 5V Line Regulation VOUT2 125°C 25°C –45°C OUTPUT VOLTAGE (V) 5.004 5.002 5.000 4.998 4.994 100 6658 G86 5.006 4.996 1 10 OUTPUT CURRENT (mA) 20 –10 0.1 100 125°C 25°C –45°C 5.004 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE CHANGE (ppm) 125°C 25°C –45°C 0 125°C 25°C –45°C 30 5V Line Regulation VOUT1 5.006 10 25 50 75 100 125 150 TEMPERATURE (°C) 6658 G85 5V VOUT2 Load Regulation, Sinking 20 0 5V VOUT1 Load Regulation, Sinking 6658 G84 30 VOUT1 VOUT2 6658 G83 5V VOUT2 Load Regulation, Sourcing 10 40 4.998 6658 G82 5V VOUT1 Load Regulation, Sourcing –30 0.1 5.000 4.994 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) 6658 G81 –25 5.002 4.996 4.994 –50 –25 25 50 75 100 125 150 TEMPERATURE (°C) ILOAD1 = 150mA 5.004 OUTPUT VOLTAGE (V) 5.004 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 5.004 5.006 THREE TYPICAL PARTS OUTPUT VOLTAGE CHANGE (ppm) 5.006 5.002 5.000 4.998 4.996 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 6658 G87 40 6658 G88 4.994 0 5 10 15 20 25 30 INPUT VOLTAGE (V) 35 40 6658 G89 Rev. C For more information www.analog.com 17 LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 5V Minimum VIN to VOUT1 Differential (Sourcing) 5V Supply Current vs Input Voltage 2.5 5V Minimum VIN to VOUT2 Differential (Sourcing) 200 100 100 1.5 1.0 0.5 0 125°C 25°C –45°C 0 4 8 10 1 0.1 1.1 12 16 20 24 28 32 36 40 INPUT VOLTAGE (V) VIN = VIN1 = VIN2 125°C 25°C –45°C 1.3 1.5 1.7 1.9 2.1 INPUT–OUTPUT VOLTAGE (V) 6658 G90 120 60 100 1 10 FREQUENCY (kHz) 100 0 0.01 1000 20 CNR = 1µF CNR = 10µF 0.1 1 10 FREQUENCY (kHz) 100 40 0 0.01 ILOAD2 = 0A ILOAD2 = 50mA 0.1 1 10 FREQUENCY (kHz) 100 1000 0.1 1 10 FREQUENCY (kHz) 100 5V VOUT1 AC Output Impedance 150mA Load 1 IOUT1 = 10mA 0.1 0.01 0.001 0.0001 0.01 COUT1 = 1µF COUT1 = 50µF 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G97 6658 G96 1000 6658 G95 OUTPUT IMPEDANCE (Ω) 60 20 1 OUTPUT IMPEDANCE (Ω) 80 0 0.01 1000 5V VOUT1 AC Output Impedance 10mA Load CNR = 10µF COUT2 = 1µF 100 ILOAD1 = 0A ILOAD1 = 150mA 6658 G94 5V VOUT2 Power Supply Rejection Ratio vs Frequency 120 60 40 20 CNR = 1µF CNR = 10µF CNR = 10µF COUT1 = 1µF 80 6658 G93 PSRR (dB) 120 40 0.1 2.1 5V VOUT1 Power Supply Rejection Ratio vs Frequency PSRR (dB) PSRR (dB) PSRR (dB) 40 0 0.01 1.3 1.5 1.7 1.9 INPUT–OUTPUT VOLTAGE (V) 6658 G92 80 20 VIN = VIN1 = VIN2 125°C 25°C –45°C 0.1 1.1 2.3 COUT2 = 1µF ILOAD2 = 0A 100 80 60 1 5V VOUT2 Power Supply Rejection Ratio vs Frequency COUT1 = 1µF ILOAD = 0A 100 10 6658 G91 5V VOUT1 Power Supply Rejection Ratio vs Frequency 120 OUTPUT CURRENT (mA) OUTPUT CURRENT (A) INPUT CURRENT (mA) 2.0 IOUT1 = 150mA 0.1 0.01 0.001 0.0001 0.01 COUT1 = 1µF COUT1 = 50µF 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G98 Rev. C 18 For more information www.analog.com LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 5V VOUT2 AC Output Impedance 1mA Load 1 IOUT2 = 1mA OUTPUT IMPEDANCE (Ω) 0.1 0.01 0.001 0.1 1 10 FREQUENCY (kHz) 100 5V/DIV 5V/DIV VOUT2 CNR = OPEN COUT1 = COUT2 = 1µF 50µs/DIV COUT2 = 1µF COUT2 = 50µF 0.1 1 10 FREQUENCY (kHz) 100 6658 G101 1000 6658 G100 5V Channel to Channel Load Isolation VOUT1 to VOUT2 140 50mVRMS SIGNAL ON VOUT2 120 100 80 60 40 ILOAD2 = 150mA ILOAD2 = 0A 0.1 VOUT1 0.001 5V Channel to Channel Load Isolation VOUT2 to VOUT1 0 0.001 5V/DIV 0.01 6658 G99 20 VIN 5V/DIV VBYPASS 0.1 0.0001 0.01 1000 5V Turn-On Characteristic IOUT2 = 50mA 1 10 FREQUENCY (kHz) 100 1000 VOUT2 CHANNEL TO CHANNEL ISOLATION (dB) 0.0001 0.01 COUT2 = 1µF COUT2 = 50µF VOUT1 CHANNEL TO CHANNEL ISOLATION (dB) OUTPUT IMPEDANCE (Ω) 1 5V VOUT2 AC Output Impedance 50mA Load 140 50mVRMS SIGNAL ON VOUT1 120 100 80 60 40 20 0 0.001 6658 G102 ILOAD2 = 50mA ILOAD2 = 0A 0.1 1 10 FREQUENCY (kHz) 100 1000 6658 G103 5V VOUT2 Output Noise 0.1Hz to 10Hz 5V VOUT1 Output Noise 0.1Hz to 10Hz OUTPUT NOISE 2µV/DIV OUTPUT NOISE 2µV/DIV 1s/DIV 6658 G104 1s/DIV 6658 G105 Rev. C For more information www.analog.com 19 LT6658 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VIN = VIN1 = VIN2 = VOUT1_F + 2.5V = VOUT2_F + 2.5V except LT6658-1.2 where VIN = VIN1 = VIN2 = 4.5V, COUT1 = COUT2 = 1µF, ILOAD = 0mA, unless otherwise noted. The characteristic curves are similar across the LT6658 family. Curves from the LT6658-1.2, LT6658-2.5 and the LT6658-5 represent the full range of typical performance of all voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output. 5V VOUT1 Output Voltage Noise Spectrum ILOAD = 0mA 700 5V VOUT2 Output Voltage Noise Spectrum ILOAD = 0mA 700 COUT1 = 1µF COUT2 = 1µF 600 NOISE VOLTAGE (nV/√Hz) NOISE VOLTAGE (nV/√Hz) 600 500 400 CNR = OPEN 300 200 100 0.1 400 CNR = OPEN 300 200 100 CNR = 10µF 0 0.01 500 1 10 FREQUENCY (kHz) 100 CNR = 10µF 0 0.01 1000 0.1 1 10 FREQUENCY (kHz) 100 6658 G106 6658 G107 5V Line Transient Response 500mV/DIV 2mV/DIV 2mV/DIV 2mV/DIV 5V Line Transient Response VIN 500mV/DIV VBYPASS 2mV/DIV VOUT1 1mV/DIV VOUT2 1mV/DIV CNR = OPEN COUT1 = COUT2 = 1µF VIN VBYPASS VOUT1 VOUT2 CNR = 1µF COUT1 = COUT2 = 1µF VIN = 7.5V TO 8V ILOAD = 0mA 6658 G108 50µs/DIV 1000 VIN = 7.5V TO 8V ILOAD = 0mA 50µs/DIV 6658 G109 5V VOUT1 and VOUT2 Current Limit 5V Line Transient Response 250 2mV/DIV 1mV/DIV VIN 225 VBYPASS 200 VOUT1 VOUT2 1mV/DIV CNR = 1µF COUT1 = COUT2 = 1µF VIN = 7.5V TO 8V ILOAD = 50mA 50µs/DIV 6658 G110 CURRENT LIMIT (mA) 500mV/DIV 175 150 125 100 75 VIN = 7.5V IOUT1 IOUT2 50 25 0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 6658 G111 Rev. C 20 For more information www.analog.com LT6658 PIN FUNCTIONS GND (Pins 1, 2, 6, Exposed Pad Pin 17): These pins are the main ground connections and should be connected into a star ground or ground plane. The exposed pad must be soldered to ground for good electrical contact and rated thermal performance. OD (Pin 9): Output Disable. This active low input disables both outputs. BYPASS (Pin 3): Bypass Pin. This requires a 1μF capacitor for bandgap stability. VIN1 (Pin 11): Input Voltage Supply for Buffer 1. Bypass VIN1 with 0.1μF capacitor to ground. This pin supplies power to buffer amplifier 1. DNC (Pin 4, 16): Do Not Connect. Keep leakage current from these pins to a minimum. NR (Pin 5): Noise Reduction Pin. To band limit the noise of the reference, connect a capacitor between this pin and ground. See Applications Information section. VOUT2_S (Pin 7): VOUT2 Kelvin Sense Pin. Connect this pin directly to the load. VOUT2_F (Pin 8): VOUT2 Output Voltage. A 1μF to 50μF output capacitor is required for stable operation. This output can source up to 50mA. VIN2 (Pin 10): Input Voltage Supply for Buffer 2. Bypass VIN2 with 0.1μF capacitor to ground. This pin supplies power to buffer amplifier 2. VOUT1_F (Pin 12): VOUT1 Output Voltage. A 1μF to 50μF output capacitor is required for stable operation. This output can source up to 150mA. VOUT1_S (Pin 13): VOUT1 Kelvin Sense Pin. Connect this sense pin directly to the load. VIN (Pin 14): Input Voltage Supply. Bypass VIN with 0.1μF capacitor to ground. NC (Pin 15): No Connect. Rev. C For more information www.analog.com 21 LT6658 BLOCK DIAGRAM 14 9 VIN OD VIN2 4 DNC VOUT2_F BUFFER 2 16 DNC 15 NC R4 VOUT2_S THERMAL SHUTDOWN VIN1 VOUT1_F BUFFER 1 R2 GND 2 8 7 11 R1 BANDGAP GND 1 10 12 GND 6 R3 17 GND 3 BYPASS 5 VOUT1_S 13 NR 6658 BD Voltage Option (V) R1 (Ω) R2 (Ω) R3, R4 (Ω) 1.2 400 9600 768 1.8 400 2903 705 2.5 400 OPEN 800 3 400 OPEN 800 3.3 400 OPEN 800 5 400 OPEN 800 Rev. C 22 For more information www.analog.com LT6658 APPLICATIONS INFORMATION The LT6658 combines the low noise and accuracy of a high performance voltage reference and the high current drive of a regulator. The LT6658 Refulator provides two precise low noise outputs with Kelvin sense pins that maintain their precision even when large voltage or current transients exist on the adjacent buffer. The LT6658 architecture consists of a low drift bandgap reference followed by an optional noise reduction stage and two independent buffers. The bandgap reference and the buffers are trimmed for low drift and high accuracy. The high gain buffers ensure outstanding line and load regulation. The guidance that follows describes how to reduce noise, lower power consumption, generate different output voltages, and maintain low drift. Also included are notes on internal protection circuits, PCB layout, and expected performance. Buffer 1 has a 2.5V output, VIN1 can be operated at 5V. If Buffer 2’s output is run at 3V, run VIN2 at 5.5V. The power savings gained by minimizing each supply voltage can be considerable. Excessive ground current and parasitic resistance in ground lines can degrade load regulation. Unlike an LDO, the ground of the LT6658 is designed such that ground current does not increase substantially when sourcing a large load current. All three ground pins and exposed pad should be connected together on the PCB, through a ground plane or through a separate trace terminating at a star ground. The supply pins can be powered up in any order without an adverse response. However, all three pins need the minimum specified voltage for proper operation. INDICATES CURRENT FLOW Supply Pins and Ground The LT6658 can operate with a supply voltage from VOUT  +  2.5V, to 36V. To provide design flexibility, the LT6658 includes 3 supply pins. The VIN pin supplies power to the bandgap voltage reference. The VIN1 and VIN2 pins supply power to buffer amplifiers 1 and 2, respectively. Figure  1 illustrates how current flows independently through each of the output buffers. The simplest configuration is to connect all three supply pins together. To reduce power consumption or isolate the buffer amplifiers, separate the supply pins and drive them with independent supplies. Separate VIN,VIN1 and VIN2 supply pins isolate the bandgap reference and the two outputs VOUT1_F and VOUT2_F from each other. For example, a load current surge through VIN1 to VOUT1_F is isolated from VOUT2_F and the bandgap voltage reference. In Figure  2, a 140mA load current pulse on Buffer 1 and the resulting output waveforms are shown. Despite the large current step on Buffer 1, there is only a small transient at the output of Buffer 2. This isolation of two buffer outputs is important when providing a stable voltage reference to noise-sensitive circuits such as an ADC or DAC. In addition, power can be minimized by providing each supply pin with its minimum voltage. For example, if 14 11 10 VIN1 VIN2 VIN + – LT6658-2.5 + – + – BANDGAP + – THERMAL SHUTDOWN + – GND 1,2 VOUT2_F VOUT1_F 8 12 LOAD2 LOAD1 GND GND 17 6 6658 F01 Figure 1. LT6658 Current Flow through the Supply Pins LOAD CURRENT 100mA/DIV 20mV/DIV 100µV/DIV VOUT1 VOUT2 COUT1 = 10µF COUT2 = 10µF 50µs/DIV 6658 F02 Figure 2. 10mA to 150mA Load Step on VOUT1 Rev. C For more information www.analog.com 23 LT6658 APPLICATIONS INFORMATION Each input voltage pin requires a 0.1µF capacitor located as close to the supply pin as possible. A 10µF capacitor is recommended for each supply where the supply enters the board. When the supply pins are connected together, a single 0.1µF and single 10µF capacitor can be used. The BYPASS pin requires a 1µF capacitor for stability. Using the BYPASS Pin as a Reference The BYPASS pin requires a 1μF capacitor for stability and provides a bandgap voltage to the output buffers. The block diagram includes a voltage divider comprised of R1 and R2. R2 is open on the four voltage options 2.5V, 3V, 3.3V and 5V. Two voltage options, 1.2V and 1.8V, include resistor R2 creating a voltage divider. The voltage at the BYPASS pin for these two options is different than the specified output voltage. The table below summarizes the BYPASS pin voltage with respect to the output voltage. Care should be exercised in choosing an output capacitor, as some capacitors tend to deviate from their specified value as operating conditions change. Although ceramic capacitors are small and inexpensive, they can vary considerably over the DC bias voltage. For example, the capacitance value of X5R and X7R capacitors will change significantly over their rated voltage range as shown in Figure 3. In this example the 1µF X5R capacitor loses almost 75% of its value at its rated voltage of 10V. 1.2 0.8 0.6 0.4 0.2 0.0 Table 1. BYPASS Pin V Voltage Voltage Option (V) BYPASS Pin Voltage (V) 1.2 1.25 1.8 2.048 2.5 2.5 3.0 3.0 3.3 3.3 5.0 5.0 X5R X7R 1.0 CAPACITANCE (µF) Input Bypass Capacitance 0 1 2 3 4 5 6 DC BIAS (V) 7 8 9 10 6658 F03 Figure 3. Capacitance Value of a 1µF X7R and 1µF X5R Over Its Full Rated Voltage The BYPASS pin can be used as an additional voltage reference pin. It nominally can source and sink 10mA. Note that any loading effect on the BYPASS pin gets passed to the output buffers. That is, if the BYPASS pin is pulled down by 100mV, the output pins will respond similarly. Stability and Output Capacitance The LT6658 is designed to be stable for any output capacitance between 1µF and 50µF, under any load condition, specified input voltage, or specified temperature. Choosing a suitable capacitor is important in maintaining stability. Preferably a low ESR and ESL capacitor should be chosen. The value of the output capacitor will affect the settling response. X5R and X7R capacitors will also vary up to 20% or more over a temperature range of –55°C to 125°C. This change in capacitance will be combined with any DC bias voltage variation. Film capacitors do not vary much over temperature and DC bias as much as X5R and X7R capacitors, but generally they are only rated to 105°C. Film capacitors are also physically larger. Effective series resistance (ESR) in the output capacitor can add a zero to the loop response of the output buffers creating an instability or excessive ringing. For the best results keep the ESR at or below 0.15Ω. One measure of stability is the closed loop response of the output buffer. By driving the NR pin, a closed loop response can be obtained. In Figure 4 the closed loop response of the output buffer with three different output capacitance values is shown. In the Figure 5 the same plot is repeated with a 150mA load. Rev. C 24 For more information www.analog.com LT6658 APPLICATIONS INFORMATION A large value electrolytic capacitor with a 1µF to 50µF ceramic capacitor in parallel can be used on the output pins. The buffers will be stable, and the bandwidth will be lower. 20 GAIN (dB) 10 the BYPASS and VOUT1_F pins for three different output capacitor values. The start-up response is limited by the current limit in the bandgap charging the BYPASS capacitor. The turn-on time is also restricted by the current limit in the output buffer and the size of the output capacitor. A larger output capacitor will take longer to charge. Adding a capacitor to the NR pin will also affect turn-on time. COUT1 = 1µF 5V/DIV 0 VBYPASS 2V/DIV COUT1 = 50µF VOUT1 COUT1 = 1µF 2V/DIV VOUT1 COUT1 = 10µF 2V/DIV VOUT1 COUT1 = 50µF 2V/DIV –10 COUT1 = 10µF –20 0.01 VIN 0.1 1 10 FREQUENCY (kHz) 100 1k 6658 F06 100µs/DIV 6658 F04 Figure 4. LT6658 Closed Loop Response of Buffer 1 for 3 Values of Output Capacitance and No Load 20 15 Figure 6. Start-Up Response on the BYPASS and VOUT1_F Pins The test circuit for the transient response test is shown in Figure 7. The transient response due to load current steps are shown in Figures 8, 9, and 10. GAIN (dB) 10 COUT1 = 1µF 5 11 12 0 –5 –10 COUT1 = 10µF –15 –20 0.01 VIN 5V COUT1 = 50µF 14 9 1 10 FREQUENCY (kHz) VOUT2_F VIN2 VOUT2_S 100 1k 6658 F05 7 OD 1µF LT6658-2.5 VOUT1_F 1µF 10Ω 8 VIN 0.1µF 3 0.1 VIN1 BYPASS VOUT1_S GND 1, 2, 6, 17 IGEN 12 13 1µF 6658 F07 Figure 5. LT6658 Closed Loop Response of Buffer 1 for 3 Values of Output Capacitance and 150mA Load Buffer 2 has a similar response. Start-Up and Transient Response When the LT6658 is powered up, the bandgap reference charges the capacitor on the BYPASS pin. The output buffer follows the voltage on the BYPASS pin charging the output capacitor. Figure 6 shows the start-up response on Figure 7. Load Current Response Time Test Circuit In Figure 8 and Figure 9, a 75mA and 140mA load step is applied to Buffer 1, respectively. In Figure 10, a 40mA load step is applied to Buffer 2. The settling time is determined by the size and edge rate of the load step, and the size of the output capacitor. Rev. C For more information www.analog.com 25 LT6658 APPLICATIONS INFORMATION output voltages. Unity gain is configured by tying the sense and force pins together. 85mA 10mA 20mV/DIV IOUT1 VOUT1 VOUT2 50µV/DIV CNR = 0.1µF COUT1 = 1µF COUT2 = 1µF 10µs/DIV 6658 F08 Figure 8. LT6658-2.5 Buffer 1 Response to 75mA Load Step 150mA When using non-unity gain configurations, VOS drift errors are possible. There is an 800Ω resistor in the Kelvin sense line which is designed to cancel base current variation on the input of the buffer amplifier. Matching the impedances on the positive and negative inputs reduces base current error and minimizes VOS drift. A feedback network will have a small base current flowing through the feedback resistor possibly causing a small VOS drift. IOUT1 10mA 20mV/DIV 100µV/DIV VOUT1 VOUT2 CNR = 0.1µF COUT1 = 1µF COUT2 = 1µF 10µs/DIV 6658 F09 Figure 9. LT6658-2.5 Buffer 1 Response to 140mA Load Step 50mA IOUT2 10mA 5mV/DIV 50µV/DIV Figure 11 provides an example where Buffer 2 is configured with a gain of 2. More examples are provided in the Typical Applications section. When configuring a gain >1, it's important to keep in mind that each output can only swing to within 2.5V of its associated supply voltage, as specified in the dropout voltage. Also note that the absolute maximum voltage on the output pins (both force and sense) is 6V. Place the feedback resistors close to the part keeping the traces short. Avoid parasitic resistance in the high current path from the feedback resistor to ground. If possible, the resistor to ground should be connected as close as possible to the chip ground. Referring to the 2.5V VOUT1_S Pin Input Current vs Temperature plot in the Typical Performance Characteristics section, the input sense current varies about 50nA between –40°C and 125°C. This 50nA variation may cause a 0.5mV voltage change across the 10kΩ feedback resistor affecting the output voltage. VOUT2 14 VIN VOUT1 CNR = 0.1µF COUT1 = 1µF COUT2 = 1µF 10µs/DIV 11 10 VIN1 VIN2 LT6658-2.5 + – BANDGAP 6658 F10 + – VOUT2_S THERMAL SHUTDOWN GND 1,2 The output buffers can be independently configured with external resistors to add gain, permitting non-standard + – VOUT1_F VOUT1_S Figure 10. LT6658-2.5 Output 2 Response to 40mA Load Step Output Voltage Scaling VOUT2_F GND GND 17 6 8 10k 7 10k 12 13 1µF 1µF 6658 F11 Figure 11. The LT6658-2.5 with Output 2 Configured for a 5V Output Rev. C 26 For more information www.analog.com LT6658 APPLICATIONS INFORMATION To ensure the LT6658 maintains good load regulation, the Kelvin sense pins should be connected close to the load to avoid any voltage drop in the copper trace on the force pin. It only takes 10mΩ of resistance to develop a 1.5mV drop with 150mA. This would cause an ideal 2.5V output voltage to exceed the 0.05% specification at the load. The circuit in Figure 12a illustrates how an incorrect Kelvin sense connection can lead to errors. The parasitic resistance of the copper trace will cause the output voltage to change as the load current changes. As a result, the voltage at the load will be lower than the voltage at the sense line. The circuit in Figure 12b shows the proper way to make a Kelvin connection with the sense line as close to the load as possible. The voltage at the load will now be well regulated. The VOUT1_S current is typically 135nA, and a low resistance in series with the Kelvin sense input is unlikely to cause a significant error or drift. LT6658-2.5 + – 250 CNR = 0µF 200 150 CNR = 1µF 100 50 CNR = 10µF 0 0.01 0.1 VPAR + RPAR VOUT1_F 12 1000 ILOAD Figure 13. LT6658 Bandgap Output Voltage Noise Table 2. NR Capacitor Values and the Corresponding 3dB Frequency VPAR + VOUT1_F 12 100 6658 F13 RLOAD VOUT1_S 13 LT6658-2.5 1 10 FREQUENCY (kHz) – a) + – capacitor and no capacitor on the NR pin. The bandgap can be bandlimited by connecting a capacitor between the NR pin and ground. The RC product sets the low pass 3dB corner attenuating the out-of-band noise of the bandgap. An internal 400Ω ±15% resistor combines with the external capacitor to create a single-pole low pass filter. Table 2 lists capacitor values and the corresponding 3dB cutoff frequency. NOISE (nV/√Hz) Kelvin Sense Pins – RPAR VOUT1_S 13 ILOAD RLOAD 6658 F12 b) *RPAR IS THE PARASITIC RESISTANCE Figure 12. How to Make a Proper Kelvin Sense Connection Output Noise and Noise Reduction (NR) The LT6658 noise characteristic is similar to that of a high performance reference. The total noise is a combination of the bandgap noise and the noise of the buffer amplifier. The bandgap noise can be measured at the NR pin and is shown in Figure 13 with a 1μF capacitor, 10µF NR Capacitor (µF) 1.2V NR 3dB Frequency (Hz) 1.8V NR 3dB Frequency (Hz) 2.5V, 3V, 3.3V, 5V NR 3dB Frequency (Hz) 0.1 4145 4522 3979 0.22 1884 2055 1809 0.47 882 962 847 1 414 452 398 2.2 188 206 181 4.7 88 96 85 10 41 45 40 22 19 21 18 The primary trade-off for including an RC filter on the NR pin is a slower turn-on time. The effective resistance seen by the NR capacitor is 400Ω. The RC time constant (τ) for charging the NR capacitor is τ = R • C. To reach the initial accuracy specification for the LT6658, 0.05%, it will take 7.6τ of settling time. Example settling time Rev. C For more information www.analog.com 27 LT6658 APPLICATIONS INFORMATION Table 3. Settling Times for Different NR Capacitor Values NR Pin Resistance (Ω) 1.2V 384 1.8V 352 2.5, 3V, 3.3V, 5V 5V/DIV 1V/DIV 1V/DIV 400 C (μF) 7.6τ (ms) 0.01 0.03 0.1 0.29 1 2.92 0.01 0.03 0.1 0.27 1 2.68 0.01 0.03 0.1 0.30 1 3.04 VIN VNR VOUT1 CNR = 22µF 3 2 1 0.1 1 10 100 FREQUENCY (kHz) 1000 10000 6658 F15 Figure 15. LT6658-2.5 Total Integrated Output Voltage Noise with CNR = 22µF and COUT1 = 1µF, 50µF and 100µF Output Capacitors 5 CNR = 1µF COUT1 = 1µF 500µs/DIV 4 COUT1 = 1µF COUT1 = 50µF COUT1 = 100µF 0 0.01 INTEGRATED NOISE (µVRMS) Output Voltage (V) 5 INTEGRATED NOISE (µVRMS) constants are shown in Table 3. An example of the NR pin charging and the relationship to the output voltage is shown in Figure 14. The appropriate trade-off between settling time and noise limiting is specific to the demands of each unique application. COUT2 = 1µF COUT2 = 50µF COUT2 = 100µF 4 CNR = 22µF 3 2 1 0 0.01 6658 F14 0.1 1 10 100 FREQUENCY (kHz) 1000 10000 6658 F16 Figure 14. Start-up Response on the NR Pin and VOUT_F The LT6658’s two low noise buffer amplifiers measure 8nV/√Hz. The combined bandgap and buffer noise results for Buffer 1 and Buffer 2 are shown in the Typical Performance Characteristics section. Note that beyond the NR pin cutoff frequency, the noise is primarily due to the buffer amplifiers. As shown, the buffer can be bandlimited by increasing the size of the output capacitors. Figure 15 and Figure 16 show the total integrated noise of Buffer 1 and Buffer 2, respectively. Figure 16. LT6658-2.5 VOUT2 Integrated Noise with CNR = 22µF and COUT2 = 1µF, 50µF and 100µF The output voltage noise does not change appreciably as load current increases. The wide range of output capacitance capability and the NR pin capacitance allows the LT6658 noise density spectrum to be customized for specific applications. Table 4 lists the output noise for different conditions. The output and NR capacitances also affect the AC PSRR response as shown in Table 4. See the Typical Performance Characteristics section for more information. Rev. C 28 For more information www.analog.com LT6658 APPLICATIONS INFORMATION Table 4. Output Noise and Ripple Rejection Typical Values PARAMETER CONDITIONS TYP UNITS Output Noise Voltage (VOUT1 and VOUT2) Frequency = 10Hz, COUT = 1µF, CNR = 0F, ILOAD = Full Current* Frequency = 10Hz, COUT = 1µF, CNR = 10µF, ILOAD = Full Current* Frequency = 1kHz, COUT = 1µF, CNR = 0F, ILOAD = Full Current* Frequency = 1kHz, COUT = 1µF, CNR = 10μF, ILOAD = Full Current* 176 164 157 9 nV/√Hz nV/√Hz nV/√Hz nV/√Hz Output RMS Noise 10Hz to 100kHz, COUT1 = 1µF, CNR = 0F 10Hz to 100kHz, COUT1 = 1µF, CNR = 10µF 10Hz to 100kHz, COUT1 = 50µF, CNR = 22µF 10Hz to 100kHz, COUT2 = 1µF, CNR = 0F 10Hz to 100kHz, COUT2 = 1µF, CNR = 10µF 10Hz to 100kHz, COUT2 = 50µF, CNR = 22µF 26.2 1.5 0.7 21.8 1.1 0.9 ppmRMS ppmRMS ppmRMS ppmRMS ppmRMS ppmRMS Power Supply Rejection (VIN1 = VOUT1 + 3V, VIN2 = VOUT2 + 3V) VRIPPLE = 500mVP-P, fRIPPLE = 120Hz, ILOAD1 = 150mA, COUT1 = 1µF, CNR = 1µF VRIPPLE = 150mVP-P, fRIPPLE = 10kHz, ILOAD1 = 150mA, COUT1 = 1µF, CNR = 1µF VRIPPLE = 150mVP-P, fRIPPLE = 100kHz, ILOAD1 = 150mA, COUT1 = 1µF, CNR = 1µF VRIPPLE = 150mVP-P, fRIPPLE = 1MHz, ILOAD1 = 150mA, COUT1 = 1µF, CNR = 1µF VRIPPLE = 500mVP-P, fRIPPLE = 120Hz, ILOAD2 = 50mA, COUT2 = 1µF, CNR = 1µF VRIPPLE = 150mVP-P, fRIPPLE = 10kHz, ILOAD2 = 50mA, COUT2 = 1µF, CNR = 1µF VRIPPLE = 150mVP-P, fRIPPLE = 100kHz, ILOAD2 = 50mA, COUT2 = 1µF, CNR = 1µF VRIPPLE = 150mVP-P, fRIPPLE = 1MHz, ILOAD2 = 50mA, COUT2 = 1µF, CNR = 1µF 107 96 65 64 104 96 66 65 dB dB dB dB dB dB dB dB * The full current for ILOAD is 150mA and 50mA for output 1 and output 2, respectively. Power Supply Rejection The three supply pins provide flexibility to address the unique demands of each application. When connected together, the LT6658 provides excellent AC power supply rejection. Superior performance can be achieved when the supply pins are independently powered. For example, use a separate supply for the VIN pin to isolate the bandgap circuit from the outputs. Further, each buffer can be supplied independently to provide a high degree of isolation as summarized in Table 3. The start-up after enabling the LT6658 enables is determined by the size of the output and NR capacitors. Figure 17 is an example of the LT6658-2.5 being enabled and disabled. The OD pin has an internal pull-up current that will keep the output buffers enabled when the OD pin floats. In noisy environments, it is recommended that OD be tied high explicitly. 5V/DIV 1V/DIV Output Disable The OD pin disables the output stage of both output buffers. This pin is useful for disabling the buffers when fault conditions exist. For example, if external circuitry senses that the load is too hot or there is a short circuit condition, this pin can be asserted to remove the output current. This active low pin will disable the output buffers when the voltage on the pin is less than 0.8V. When the input voltage is greater than 2V the LT6658 is enabled. 1V/DIV COUT1 = 1µF COUT2 = 1µF OD VOUT1 VOUT2 500µs/DIV 6658 F17 Figure 17. The Output Disable Function Rev. C For more information www.analog.com 29 LT6658 APPLICATIONS INFORMATION Internal Protection sensing shown in Figure 18 adds only 7.5mV overhead to the supply and is set to trip at 150mA. Separate supply pins on the LT6658 permit each output buffer to have a dedicated overcurrent sense circuit. The RST signal resets the latched comparator. There are two internal protection circuits for monitoring output current and die temperature. The output stage of each output buffer is disabled when the internal die temperature is greater than 165°C. There is 11°C of hysteresis allowing the part to return to normal operation once the die temperature drops below 154°C. Power Dissipation To maintain reliable precise and accurate performance the LT6658 junction temperature should never exceed TJMAX = 150°C. If the part is operated at the absolute maximum input voltage and maximum output currents, the MSE package will need to dissipate over 7 watts of power. In addition, a short circuit protection feature prevents the output from supplying an unlimited load current. A fault or short on either output force pin will cause the output stage to limit the current and the output voltage will drop accordingly to the output fault condition. For example, if a 1Ω fault to ground occurs on Buffer 1, the circuit protection will limit both outputs. A load fault on either buffer will affect the output of both buffers. The LT6658 comes in an MSE package with an exposed pad. The thermal resistance junction to case, θJC, of the MSE package is 10°C/W. The thermal resistance junction to ambient, θJA, is determined by the amount of copper on the PCB that is soldered to the exposed pad. When following established layout guidelines the θJA can be as low as 35°C/W for the MSE package. The OD pin may also be used with external circuitry to set a latched current limit as shown in Figure 18. The LT6108-1 provides a high-side current sense, latched comparator and a reference voltage enabling a simple latched overcurrent protection circuit. The high side 5.1V TO 36V 75Ω 0.1µF 0.05Ω SENSELO 14 VIN 10 VIN2 LT6658-2.5 + – 9 OD 400Ω BANDGAP + – 3 BYPASS NR 5 1µF OUTA 11 VIN1 VOUT1_F VOUT1_S VOUT2_F VOUT2_S SENSEHI LT6108-1 INC 0.1µF 12 4k V– V+ 10k RST EN/RST OC OUTC 0.1µF VOUT1 1µF 13 8 VOUT2 1µF 7 GND 1, 2, 6, 17 1µF 6658 F27 Figure 18. LT6658-2.5V with an Overcurrent Protection Circuit Rev. C 30 For more information www.analog.com LT6658 APPLICATIONS INFORMATION As a simple example, if 2 watts are dissipated in the MSE package, the die temperature would rise 70°C above the ambient temperature. The following expression describes the rise in temperature (θJA • PTOTAL), and the increase of junction temperature over ambient temperature as where PSTATIC is the power dissipated in the LT6658 minus the output devices, VIN is the supply voltage, and ISTATIC is the current flowing through the LT6658. To calculate the power dissipated by the output devices use TJ = TA + θJA • PTOTAL P2 = (VIN2 – VOUT2) • IOUT2 where TJ is the junction temperature, TA is the ambient temperature, θJA is the thermal resistance junction to ambient, and PTOTAL is the total power dissipated in the LT6658. Further, if the package was initially at room temperature (25°C), the die would increase to 95°C. At 3 watts the die would exceed the specified H-grade temperature of 125°C. The derating curve for the MSE package is shown in Figure  19. Three different θJA curves are shown. θJA is dependent on the amount of copper soldered to the exposed pad. Multiple layers of copper with multiple vias is recommended. MAX. POWER DISSIPATION (W) 3 θJA = 35°C/W θJA = 60°C/W θJA = 85°C/W where P1 and P2 are the power dissipated in the Buffer 1 and Buffer 2 output devices, VIN1 and VIN2 are the supply voltages for each buffer, and VOUT1 and VOUT2 are the output voltages. Finally, PTOTAL = P1 + P2 + PSTATIC where PTOTAL is the total power dissipated in the package. PSTATIC tends to be much smaller than P1 or P2. To lower the power in the output devices, the supply voltage for each of the output buffers can be reduced to only 2.5V above the output voltage. For example, with a 2.5V output, using a 5V supply and maximum output current on each buffer, the total power can be calculated as P1 = (5V – 2.5V) • 0.15A = 0.375W P2 = (5V – 2.5V) • 0.05A = 0.125W 2 PSTATIC = 5V • 0.001A = 0.005W PTOTAL = 0.375W + 0.125W + 0.005W = 0.505W 1 0 P1 = (VIN1 – VOUT1) • IOUT1 which is an operating condition that can be tolerated above 100°C when proper heat sinking is used. 0 25 50 75 100 TEMPERATURE (°C) 125 6658 F18 Figure 19. MSE Derating Curve The power dissipated by the LT6658 can be calculated as three components. There is the power dissipated in the two output devices (one for each buffer) and the power dissipated within the remaining internal circuits. Calculate the power in the remaining circuits using the following expressions PSTATIC = VIN • ISTATIC In Figure 20, the output current in both buffers is increased linearly for three values of VIN where all three supply pins are connected together. As VIN and IOUT increases, the total power increases proportionally. When the supply voltage is 30V and the total output current is 200mA, the power exceeds 5W, representing a junction temperature increase of over 175°C using a best case scenario when using a MSE with a θJA = 35°C/W. Figure 21 illustrates how rapidly power increases when the supply voltage increases, especially with 200mA of total load current. If possible, reduce the voltage on VIN1 and VIN2, which in turn will reduce the power dissipated in the LT6658 package. Rev. C For more information www.analog.com 31 LT6658 APPLICATIONS INFORMATION The LT6658 is a high performance reference and extreme thermal cycling will cause thermal hysteresis and should be avoided if possible. See the Thermal Hysteresis section. 6 VIN = 5V VIN = 15V VIN = 30V 5 1000 4 LOAD CURRENT (mA) POWER (W) plotted for three values of θJA. This illustrates how a lower θJA value will remove more heat and allow more power to be dissipated through the package without damaging the part. 3 2 1 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 OUTPUT CURRENT (A) 100 10 1 6658 F19 TA = 25°C θJA = 35°C/W θJA = 60°C/W θJA = 85°C/W 1 10 100 SUPPLY VOLTAGE – LOAD VOLTAGE (V) 6658 F21 Figure 20. Power Dissipation vs Output Current When the supply voltage, VIN1 or VIN2, is greater than 30V, a hard short from either output to ground can result in more than 3 to 6 watts of instantaneous power which can damage the output devices. 7 200mA NO LOAD 6 There are three regions in the SOA plot. The top left region is the maximum rated current of the LT6658. The diagonal lines in the middle are where both the load current and supply voltage must be reduced as not to exceed TJMAX. The bottom right is the maximum voltage of the LT6658. It is important to realize the SOA limit is an absolute maximum rating at TJMAX. It is not recommended to operate at this limit for extended periods of time. 5 POWER (W) Figure 22. SOA for the LT6658 4 3 PCB Layout 2 The LT6658 is a high performance reference and therefore, requires good layout practices. Each supply pin should have 0.1µF capacitor placed close to the package. The output capacitors should also be close to the part to keep the equivalent series resistance to a minimum. As mentioned earlier, avoid parasitic resistance between the sense line and the load. Any error here will directly affect the output voltage. 1 0 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 35 40 6658 F20 Figure 21. Power Dissipation vs Supply Voltage Safe Operating Area The safe operating area, or SOA, describes the operating region where the junction temperature does not exceed TJMAX. In Figure 22, the SOA for the LT6658 is plotted. In this plot, the output voltage is 2.5V and the output current is the combined current of both buffers. The SOA is All three ground pins (1, 2, 6) , and exposed pad should be connected together, preferably in a star ground configuration or ground plane. The exposed pad, Pin 17, is electrically connected to the die and must be connected to ground. It is also necessary for good thermal conductivity; use plenty of copper and multiple vias. Rev. C 32 For more information www.analog.com LT6658 APPLICATIONS INFORMATION Long Term Drift Long term drift is a settling of the output voltage while the part is powered up. The output slowly drifts at levels of parts per million (ppm). The first 1000 hours of being powered up sees the most shift. By the end of 3000 hours, most parts have settled and will not shift appreciably. The plot in Figure 24 is representative of the LT6658 long term drift. 200 LONG TERM DRIFT (ppm) If the design requires the part to dissipate significant power, consider using 2oz copper and/or a multilayer board with a large area of copper connected to the exposed pad. Note that θJA is proportional to the amount of copper soldered to the exposed pad. Preferably the copper should be on the outermost layers of the board for good thermal dissipation. A sample layout is shown in Figure 23a. The sense lines, VOUT1_S and VOUT2_S should connect as close as possible to the top of the load. In Figure 23b, a star ground is shown where the LT6658 ground is directly connected to the bottom of the load. Connect all other grounds in the system to this same point. Minimize the resistance between GND side of the load and the LT6658 GND pins, especially for applications where the LT6658 is sinking current. This minimizes load regulation errors. 150 100 50 0 –50 0 500 1000 1500 2000 TIME (HOURS) 2500 3000 6658 F23 Figure 24. LT6658 Long Term Drift IR Reflow Shift (a) LT6658 Sample PCB Layout 10, 11, 14 LT6658-2.5 VIN, VIN1, VIN2 + – 5V TO 36V VOUT2_F 12 VOUT2_S 13 RLOAD GND 1, 2, 6, 17 STAR-GROUND 6658 F22 (b) Bring Out Ground to the Load and Make a Star Connection As with many precision devices, the LT6658 will experience an output shift when soldered to a PCB. This shift is caused by uneven contraction and expansion of the plastic mold compound against the die and the copper pad underneath the die. Critical devices in the circuit will experience a change of physical force or pressure, which in turn changes its electrical characteristics, resulting in subtle changes in circuit behavior. Lead free solder reflow profiles reach over 250°C, which is considerably higher than lead based solder. A typical lead free IR reflow profile is shown in Figure 25. The experimental results simulating this shift are shown in Figure 26. In this experiment, LT6658 is run through an IR reflow oven once and three times. Figure 23. Rev. C For more information www.analog.com 33 LT6658 TEMPERATURE (°C) 300 380s TP = 260°C TL = 217°C TS(MAX) = 200°C TS = 190°C 225 experiences extreme temperature excursions and then returns to room temperature. For example, the LT6658 rated for –40°C to 125°C was repeatedly cycled between 125°C and –40°C. Figure 27 illustrates the thermal hysteresis of the LT6658, where each time the part’s temperature passed through 25°C after cold and hot excursions, the output voltage was recorded. RAMP DOWN tP 30s T = 150°C 150 tL 130s RAMP TO 150°C 75 40s 14 120s 0 2 4 6 MINUTES 10 8 6658 F24 Figure 25. Lead Free Reflow Profile 14 MSE–16 NUMBER OF UNITS 12 NUMBER OF UNITS 0 MAX AVG HOT CYCLE 12 25°C TO 125°C TO 25°C 10 MAX AVG COLD CYCLE 25°C TO –40°C TO 25°C 8 6 4 1 CYCLE 3 CYCLES 2 0 –100 –75 –50 –25 0 25 50 75 CHANGE IN OUTPUT VOLTAGE (ppm) 10 100 6658 F26a 8 (a) LT6658 H-Grade (–40°C to 125°C) 6 4 24 22 MAX AVG HOT CYCLE 25°C TO 85°C TO 25°C 20 2 18 50 6658 F25 Figure 26. ∆VOUT1 Due to IR Reflow Shift NUMBER OF UNITS 0 –300 –250 –200 –150 –100 –50 0 CHANGE IN OUTPUT VOLTAGE (ppm) 16 14 MAX AVG COLD CYCLE 25°C TO –40°C TO 25°C 12 10 8 6 Thermal Hysteresis 4 Thermal hysteresis is caused by the same effect as IR reflow shift. However, in the case of thermal hysteresis, the temperature is cycled between its specified operating extremes to simulate how the part will behave as it 0 –100 –75 –50 –25 0 25 50 75 CHANGE IN OUTPUT VOLTAGE (ppm) 2 100 6658 F26b (b) LT6658 I-Grade (–40°C to 85°C) Figure 27. Thermal Hysteresis Rev. C 34 For more information www.analog.com LT6658 TYPICAL APPLICATIONS 200mA Reference 14 5V TO 36V 11 10 9 VIN VIN1 VOUT1_S 13 VIN2 OD 0.01Ω VOUT1_F 12 1µF LT6658-2.5 0.03Ω VOUT2_F 8 0.1µF 3 1µF VOUT2_S 7 BYPASS 1µF RLOAD GND 1, 2, 6, 17 6658 TA02 Single Supply Precision Data Acquisition Circuit 11 10 14 6.6V 9 0.1µF 12 13.7k 13 4.096V 1k OD VOUT1_F 1k V+ 8 4 + LTC6362 1k VCM 3 1 VOUT1_S 5 V– 1k 0.41V IN+ 35.7Ω 6 7 1µF REF VDD 10µF LTC2378-20 IN 35.7Ω 3.69V BYPASS GND 1, 2, 6, 17 8 2.5V 6800pF 3300pF – 2 3.69V VOUT2_F VOUT2_S 47µF 1k 1k 3.28V 0V –3.28V VIN LT6658-2.5 21.5k VCM 10µF VIN1 VIN2 6800pF – REF/DGC 6658 TA03 0.41V Rev. C For more information www.analog.com 35 LT6658 TYPICAL APPLICATIONS Driving the a Dual ADC with Independent Voltage References 5V TO 36V REFINT 14 V 11 IN VIN1 12 VOUT1_F 13 VOUT1_S 0.1µF 2.5V REFOUT1 LTC2323-16 10µF REFRTN1 1µF LT6658-2.5 REFRTN2 7.5V TO 36V 10µF 10 8 VOUT2_F VOUT2_S 7 VIN2 0.1µF BYPASS 1µF GND 1, 2, 6, 17 5V 10k REFOUT2 GND 6658 TA04 1µF 10k Driving Two Code Dependent DAC Reference Inputs. Separate DAC Reference Biasing Eliminates Code Dependent Reference Current Interaction 14 11 10 5V < VIN < 36V 0.1µF 12 13 VIN VIN1 LT6658-2.5 VIN2 VOUT1_F VOUT2_F VOUT1_S VOUT2_S 8 7 BYPASS 1µF VREF 5V 0.1µF RPAR* GND 1, 2, 6, 17 4.7µF 7 REF VDD VDD LTC2641-16 CS 3 SCLK 4 DIN 5 CLR 0.1µF 1 7 2 VREF 5V 2.5V RPAR* 2.5V 4.7µF 1 REF LTC2641-16 16-BIT DAC VOUT 6 GND 2 CS 3 SCLK 4 DIN 5 CLR 8 VOUT 6 16-BIT DAC GND 8 6658 TA05 *RPAR IS THE PARASITIC RESISTANCE OF THE BOARD TRACE AND SHOULD BE > 0.048Ω TO MAINTAIN GOOD INL Rev. C 36 For more information www.analog.com LT6658 TYPICAL APPLICATIONS Common Errors for Non-Unity Gain Applications Load Voltage Error Due to Parasitic Resistance LOAD VOLTAGE ERROR (mV) 100 7.5V TO 36V 14 V IN 10 V 11 V IN2 IN1 LT6658-2.5 + – 1µF BANDGAP 0.1µF 3 VOUT1_S BYPASS THERMAL SHUTDOWN 1µF 2 GND VOUT1_F 1 GND + – VOUT2_F VOUT2_S 17 GND 6 GND 12 R2 ILOAD 10k 8 1 0.1 -10 R1 10k 13 10 0.1Ω 0.05Ω 0.01Ω 10 30 50 70 90 110 130 150 LOAD CURRENT (mA) VERROR = ILOAD • RPAR RPAR VIDEAL = 5V 7 1µF 1µF RLOAD 6658 TA06 KELVIN SENSE ERROR: RPAR WILL CAUSE AN ERROR VERROR = ILOAD • RPAR. CONNECT THE TOP OF R1 DIRECTLY TO THE TOP OF RLOAD. RESISTOR TOLERANCE ERROR: GAIN NETWORK ERROR CAN BE REDUCED BY USING A MATCHED RESISTOR NETWORK SUCH AS THE LT5400. ILOAD (mA) ± ERROR (mV) 0.05 0 35.4 0.05 150 42.9 0.1 0.05 0 3.5 0.1 0.05 150 11.0 0.1 0.02 150 6.5 0.1 0.01 150 5.0 R1 AND R2 TOLERANCE (%) RPAR (Ω) 1 1 R1 AND R2 TOLERANCE ERRORS ADDED ROOT-SUM-SQUARE Rev. C For more information www.analog.com 37 LT6658 TYPICAL APPLICATIONS Scale Buffer 1 Up and Scale Buffer 2 Down 5.8V TO 36V 14 VIN 10 VIN1 LT6658-2.5 + – 9 OD 400Ω BANDGAP 11 VIN2 VOUT1_F VOUT1_S + – 0.1µF 3 VOUT2_F VOUT2_S BYPASS NR 5 12 13 8 7 GND RF1 8.76k 1.8V AT 50mA 1µF RIN1 10k RF2 3.2k 3.3V AT 150mA 1µF  R  VOUT2 _ F = 2.5V  1+ F2   R IN2    R •R  VOUT1_ F = 2.5V  1– F2 F1  RIN2 • RIN1   RIN2 10k 1, 2, 6, 17 2.5V AT 10mA 1µF 1µF 6658 TA12 Automotive Reference and Supply Voltage Application 14 11 10 12V BATTERY 9 VIN VOUT2_F VIN1 VOUT2_S 1µF LT6658-2.5 0.1µF 1µF VOUT1_F 3 1µF 7 VIN2 OD 2.5V 50mA REFERENCE VOLTAGE 8 BYPASS VOUT1_S 12 13 GND 1, 2, 6, 17 10k 5V 150mA SUPPLY VOLTAGE 1µF 10k 6658 TA07 Rev. C 38 For more information www.analog.com LT6658 TYPICAL APPLICATIONS LT6658 Biasing Multiple Strain Gauges 10µF 0.1µF 1µF 1µF VCC 7.5V TO 36V 11 10 14 10µF VIN1 VOUT2_F VIN2 VOUT2_S 8 2.5V 1µF + VIN+ – VIN– VREF VREF 7 335Ω LTC2440 1µF 335Ω GND VIN VCC 335Ω LTC2440 + VREF VIN+ VREF– VIN– 335Ω 335Ω GND 335Ω LT6658-2.5 9 3 1µF OD VOUT1_F BYPASS VOUT1_S 5V 12 13 GND GND (PAD) 1, 2, 6 17 10k 10µF 10k 1µF 0.1µF 1µF VCC 1µF + VIN+ – VIN– VREF VREF LTC2440 AND STRAIN GAUGE BIAS GND VCC 335Ω LTC2440 1µF 335Ω 335Ω 335Ω LTC2440 + VREF VIN+ VREF– VIN– GND 335Ω 335Ω 6658 TA08 Rev. C For more information www.analog.com 39 LT6658 TYPICAL APPLICATIONS Recursive Reference Application (VOUT1 Supplies Power to VIN and VIN2) 7.5V TO 36V 1.5k 1W 180 1N4148 1N4148 14 10µF 11 VIN LT6658-2.5 10 VIN1 VIN2 VOUT2_F 400Ω BANDGAP 1µF VOUT2_S VOUT1_F VOUT1_S VOUT2 2.5V 8 7 POWER SUPPLY REJECTION RATIO (dB) 4.7V 1N5230 Recursive Reference Power Supply Rejection Ratio 10µF 10k 140 120 100 80 60 40 20 0 0.001 VOUT1 5V 12 VOUT1 VOUT2 THEORETICAL 160 0.01 0.1 1 FREQUENCY (kHz) 10 100 6658 TA09b 1µF 13 10k 3 BYPASS 5 1µF NR GND 1, 2, 6, 17 1µF 6658 TA09a Low Drift Regulator Application 5V TO 13.2V 11 VIN LT6658-2.5 VIN1 10 Precision Low Drift Application Drift = 1.5ppm/°C; –40°C to 125°C VIN2 8 400Ω BANDGAP 7 1µF 12 13 LTC6655-2.5 IN SHDN BYPASS 3 5 NR 1µF VOUT2_S VOUT1_F VOUT1_S VOUT1 2.5V 1µF OUTS 1µF 2.502 VOUT2 2.5V GND 1,2,6,17 OUTF GND VOUT2_F OUTPUT VOLTAGE (V) 14 2.501 2.500 2.499 2.498 –40 –20 1µF NR VOUT1 VOUT2 0 20 40 60 80 100 120 140 TEMPERATURE (°C) 6658 TA10b 6658 TA10a Rev. C 40 For more information www.analog.com LT6658 PACKAGE DESCRIPTION MSE Package 16-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1667 Rev F) BOTTOM VIEW OF EXPOSED PAD OPTION 2.845 ±0.102 (.112 ±.004) 5.10 (.201) MIN 2.845 ±0.102 (.112 ±.004) 0.889 ±0.127 (.035 ±.005) 8 1 1.651 ±0.102 (.065 ±.004) 1.651 ±0.102 3.20 – 3.45 (.065 ±.004) (.126 – .136) 0.305 ±0.038 (.0120 ±.0015) TYP 16 0.50 (.0197) BSC 4.039 ±0.102 (.159 ±.004) (NOTE 3) RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.35 REF 0.12 REF DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY 9 NO MEASUREMENT PURPOSE 0.280 ±0.076 (.011 ±.003) REF 16151413121110 9 DETAIL “A” 0° – 6° TYP 3.00 ±0.102 (.118 ±.004) (NOTE 4) 4.90 ±0.152 (.193 ±.006) GAUGE PLANE 0.53 ±0.152 (.021 ±.006) DETAIL “A” 1.10 (.043) MAX 0.18 (.007) SEATING PLANE 0.17 – 0.27 (.007 – .011) TYP 1234567 8 0.50 (.0197) BSC NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL NOT EXCEED 0.254mm (.010") PER SIDE. 0.86 (.034) REF 0.1016 ±0.0508 (.004 ±.002) MSOP (MSE16) 0213 REV F Rev. C For more information www.analog.com 41 LT6658 PACKAGE DESCRIPTION DE Package 16-Lead Plastic DFN (4mm × 3mm) (Reference LTC DWG # 05-08-1732 Rev Ø) 0.70 ±0.05 3.30 ±0.05 3.60 ±0.05 2.20 ±0.05 1.70 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.45 BSC 3.15 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 ±0.10 (2 SIDES) 9 R = 0.05 TYP R = 0.115 TYP 0.40 ±0.10 16 3.30 ±0.10 3.00 ±0.10 (2 SIDES) 1.70 ±0.10 PIN 1 NOTCH R = 0.20 OR 0.35 × 45° CHAMFER PIN 1 TOP MARK (SEE NOTE 6) (DE16) DFN 0806 REV Ø 8 0.200 REF 1 0.23 ±0.05 0.45 BSC 0.75 ±0.05 3.15 REF 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WGED-3) IN JEDEC PACKAGE OUTLINE MO-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE Rev. C 42 For more information www.analog.com LT6658 REVISION HISTORY REV DATE DESCRIPTION A 10/17 Addition of 1.2V, 1.8V, 3V, 3.3V, 5V Options The term “Channel” was replaced by the term “Buffer” New Application Section “Using the BYPASS Pin as a Reference” Edits for clarification to Application Section “Output Voltage Scaling” Addition of Figure 18 and use of the OD pin to Application Section “Internal Protection” Updated Typical Application “200mA Reference” B C 07/18 05/19 PAGE NUMBER 1-18, 20, 25, 26 ALL 22 24 28 Updated Typical Application “Recursive Reference Application” 33 Changed Load Regulation 1 Changed VIN Minimum Voltage 4 37 Changed Output Short-Circuit Current and added Note 11 5 Corrected Table 4 27 Corrected Typical Application circuit TA12 35 Updated Typical Application 40 Added 4mm × 3mm DFN package and order information Updated Note 11 1–5 7 Rev. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license For is granted implication or otherwise under any patent or patent rights of Analog Devices. more by information www.analog.com 43 LT6658 TYPICAL APPLICATION Providing a Precision Reference and Supply Voltage to a Mixed Signal Application 7.5V TO 36V 14 11 VIN VIN1 10 VIN2 LT6658-2.5 8 1µF 400Ω BANDGAP 7 12 VOUT2_F 4.096V 13.7k VOUT2_S VOUT1_F 5V 10k 13 BYPASS 3 5 1µF 10µF 1µF 464Ω 10k GND 1,2,6,17 1µF TO OTHER ANALOG CIRCUITS 1k 10µF NR VOUT1_S 21k 47µF (X7R, 1210 SIZE) 2.5V 1k 1k 3.28V 0V –3.28V 1k 35.7Ω – + 1k VOCM + 1k – S 35.7Ω LTC6362 6800pF IN+ 3300pF VDD LTC2379-18 IN– 6800pF REF REF/DGC GND LT5400-4 6658 TA11 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1460 Micropower Series References 20mA Output Drive, 0.075% Accuracy, 10ppm/°C Drift LT1461 Precision Low Dropout Series References 50mA Output Drive, 0.04% Accuracy, 3ppm/°C Drift, 50µA Supply Current, 300mV Dropout LT6654 All Purpose, Rugged and Precise Series References ±10mA Output Drive, 0.05% Accuracy, 10ppm/°C Drift, 100mV Dropout, 1.6ppmP-P Noise (0.1Hz to 10Hz), –55°C to 125°C LTC6655 Precision Low Noise Series References ±5mA Output Drive, 0.025% Accuracy, 2ppm/°C Max Drift, 0.25ppmP-P Noise (0.1Hz to 10Hz), –40°C to 125°C LT6660 Tiny Micropower Series References 20mA Output Drive, 0.2% Accuracy, 20ppm/°C Drift, 2mm × 2mm DFN Package LT1761 Low Noise Low Dropout Linear Regulator 100mA Output Drive, 300mV Dropout, VIN = 1.8V to 20V, 20µVRMS Noise (10Hz to 100kHz), ThinSOT™ package LT3042 Ultralow Noise, Ultrahigh PSRR Linear Regulator 200mA Output Drive, 350mV Dropout, VIN = 1.8V to 20V 0.8µVRMS Noise (10Hz to 100kHz), 79dB PSRR (1MHz) LT3050 Low Noise Linear Regulator with Current Limit and Diagnostic Functions 100mA Output Drive, 300mV Dropout, VIN = 2V to 45V, 30μVRMS Noise (10Hz to 100kHz), 50μA Supply Current, Adj. Output LT3060 Micropower, Low Noise, Low Dropout Linear Regulator 100mA Output Drive, 300mV Dropout, VIN =1.7V to 45V, 30μVRMS Noise (10Hz to 100kHz), 40μA Supply Current, Adj. Output LT3063 Micropower, Low Noise, Low Dropout Linear Regulator with Output Discharge 200mA Output Drive, 300mV Dropout, VIN =1.6V to 45V, 30μVRMS Noise (10Hz to 100kHz), 40μA Supply Current Rev. C 44 D17045-0-05/19(c) www.analog.com For more information www.analog.com  ANALOG DEVICES, INC. 2016–2019