LTC3025IDC

LTC3025 300mA Micropower VLDO Linear Regulator FEATURES n n n n n n n n n n n n n n DESCRIPTION The LTC®3025 is a micropower, VLDOTM (very low dropout) linear regulator which operates from input voltages as low as 0.9V. The device is capable of supplying 300mA of output current with a typical dropout voltage of only 45mV. A BIAS supply is required to run the internal reference and LDO circuitry while output current comes directly from the IN supply for high efficiency regulation. The low 0.4V internal reference voltage allows the LTC3025 output to be programmed to much lower voltages than available in common LDOs (range of 0.4V to 3.6V). The output voltage is programmed via two ultrasmall SMD resistors. The LTC3025’s low quiescent current makes it an ideal choice for use in battery-powered systems. For 3-cell NiMH and single cell Li-Ion applications, the BIAS voltage can be supplied directly from the battery while the input can come from a high efficiency buck regulator, providing a high efficiency, low noise output. Other features include high output voltage accuracy, excellent transient response, stability with ultralow ESR ceramic capacitors as small as 1μF short-circuit and , thermal overload protection and output current limiting. The LTC3025 is available in a tiny, low profile (0.75mm) 6-lead DFN (2mm × 2mm) package. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. VLDO is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Wide Input Voltage Range: 0.9V to 5.5V Stable with Ceramic Capacitors Very Low Dropout: 45mV at 300mA Adjustable Output Range: 0.4V to 3.6V ±2% Voltage Accuracy over Temperature Supply Load Low Noise: 80μVRMS (10Hz to 100kHz) BIAS Voltage Range: 2.5V to 5.5V Fast Transient Recovery Shutdown Disconnects Load from VIN and VBIAS Low Operating Current: IIN = 4μA, IBIAS = 50μA Typ Low Shutdown Current: IIN = 1μA, IBIAS = 0.01μA Typ Output Current Limit Thermal Overload Protection Available in 6-Lead (2mm × 2mm) DFN Package APPLICATIONS n n n n n n n Low Power Handheld Devices Low Voltage Logic Supplies DSP Power Supplies Cellular Phones Portable Electronic Equipment Handheld Medical Instruments Post Regulator for Switching Supply Noise Rejection TYPICAL APPLICATION 1.2V Output Voltage from 1.5V Input Supply 50 BIAS Li-Ion OR 3-CELL NiMH 1.5V HIGH EFFICIENCY 1.5V DC/DC BUCK 0.1μF IN 0.1μF OFF ON SHDN GND 3025 TA01 1MHz VIN Supply Rejection 1μF VOUT = 1.2V IOUT ≤ 300mA 45 40 REJECTION (dB) 35 30 25 20 15 10 5 BIAS = 3.6V VOUT = 1.2V 0 1.2 1.4 1.6 IOUT = 100mA IOUT = 300mA 1.8 2.0 VIN (V) 2.2 2.4 2.6 3025fb OUT LTC3025 ADJ 40.2k 80.6k COUT = 10μF COUT = 1μF 3025 TA01b 1 LTC3025 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) PIN CONFIGURATION TOP VIEW BIAS 1 GND 2 IN 3 7 6 SHDN 5 ADJ 4 OUT VBIAS, VIN to GND......................................... –0.3V to 6V SHDN to GND............................................... –0.3V to 6V ADJ to GND.................................................. –0.3V to 6V VOUT ........................................–0.3V to VIN + 0.3V or 6V Operating Junction Temperature Range (Note 3).................................................. –40°C to 125°C Storage Temperature Range................... –65°C to 125°C Output Short-Circuit Duration .......................... Indefinite DC6 PACKAGE 6-LEAD (2mm 2mm) PLASTIC DFN TJMAX = 125°C, θJA = 102°C/W, θJC = 20°C/W EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH LTC3025EDC#PBF LTC3025IDC#PBF LEAD BASED FINISH LTC3025EDC LTC3025IDC TAPE AND REEL LTC3025EDC#TRPBF LTC3025IDC#TRPBF TAPE AND REEL LTC3025EDC#TR LTC3025IDC#TR PART MARKING* LBDY LBDY PART MARKING* LBDY LBDY PACKAGE DESCRIPTION 6-Lead (2mm × 2mm) Plastic DFN 6-Lead (2mm × 2mm) Plastic DFN PACKAGE DESCRIPTION 6-Lead (2mm × 2mm) Plastic DFN 6-Lead (2mm × 2mm) Plastic DFN TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 1.5V, VBIAS = 3.6V, VOUT = 1.2V, COUT = 1μF CIN = 0.1μF , , CBIAS = 0.1μF (all capacitors ceramic) unless otherwise noted. PARAMETER VIN Operating Voltage (Note 4) VBIAS Operating Voltage (Note 4) VBIAS Undervoltage Lockout VIN Operating Current VBIAS Operating Current VIN Shutdown Current VBIAS Shutdown Current VADJ Regulation Voltage (Note 5) IADJ ADJ Input Current OUT Load Regulation (Referred to ADJ Pin) VIN Line Regulation (Referred to ADJ Pin) IOUT = 10μA IOUT = 10μA VSHDN = 0V VSHDN = 0V 1mA ≤ IOUT ≤ 300mA, 1.5V ≤ VIN ≤ 5V 1mA ≤ IOUT ≤ 300mA, 1.5V ≤ VIN ≤ 5V VADJ = 0.45V ΔIOUT = 1mA to 300mA VIN = 1.5V to 5V, VBIAS = 3.6V, VOUT = 1.2V, IOUT = 1mA l ELECTRICAL CHARACTERISTICS CONDITIONS MIN l l l l l TYP MAX 5.5 5.5 UNITS V V V μA μA μA μA V V nA mV mV 0.9 2.5 2.2 4 50 1 0.01 0.395 0.392 –50 0.4 0.4 0 –0.2 0.07 2.5 10 80 5 1 0.405 0.408 50 3025fb 2 LTC3025 ELECTRICAL CHARACTERISTICS PARAMETER BIAS Line Regulation (Referred to ADJ Pin) VIN to VOUT Dropout Voltage (Notes 4, 6, 7) VBIAS to VOUT Dropout Voltage (Note 4) IOUT Continuous Output Current IOUT Current Limit en Output Voltage Noise VIH SHDN Input High Voltage VIL SHDN Input Low Voltage IIH SHDN Input High Current IL SHDN Input Low Current SHDN = 1.2V SHDN = 0V VADJ = 0V f = 10Hz to 100kHz, IOUT = 300mA l l The l denotes the specifications which apply over the full operating , , temperature range, otherwise specifications are at TA = 25°C. VIN = 1.5V, VBIAS = 3.6V, VOUT = 1.2V, COUT = 1μF CIN = 0.1μF CBIAS = 0.1μF (all capacitors ceramic) unless otherwise noted. CONDITIONS VIN = 1.5V, VBIAS = 2.6V to 5V, VOUT = 1.2V IOUT = 1mA VBIAS = 2.8V, VIN = 1.5V, VADJ = 0.37V, IOUT = 300mA l l l l MIN TYP 1.7 45 MAX 5.5 100 1.4 UNITS mV mV V mA mA μVRMS V 300 680 80 0.9 0.3 –1 –1 1 1 V μA μA 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: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. Note 3: The LTC3025 regulator is tested and specified under pulse loadconditions such that TJ ≈ TA. The LTC3025 is 100% production tested at 25°C. Performance at –40°C and 125°C is assured by design, characterization and correlation with statistical process control. The LTC3025I is guaranteed to meet performance specifications over the full –40°C and 125°C temperature range. Note 4: For the LTC3025, a regulated output voltage will only be available when the minimum IN and BIAS Operating Voltages as well as the IN to OUT and BIAS to OUT Dropout Voltages are all satisfied. Note 5: Operating conditions are limited by maximum junction temperature. The regulated output voltage specification will not apply for all possible combinations of input voltage and output current. When operating at maximum input voltage, the output current range must be limited. When operating at maximum output current, the input voltage range must be limited. Note 6: Dropout voltage is minimum input to output voltage differential needed to maintain regulation at a specified output current. In dropout, the output voltage will be equal to VIN – VDROPOUT. Note 7: The DFN output FET on-resistance in dropout is guaranteed by correlation to wafer level measurements. 3025fb 3 LTC3025 TYPICAL PERFORMANCE CHARACTERISTICS Dropout Voltage vs IOUT 70 60 DROPOUT VOLTAGE (mV) 50 40 30 20 10 0 0 50 100 TA = –40°C TA = 125°C IBIAS (μA) TA = 25°C VBIAS = 2.8V 400 350 300 IBIAS (μA) 250 125°C 200 25°C 150 –40°C 100 50 200 150 IOUT (mA) 250 300 3025 G01 Operating BIAS Current vs Output Load 80 BIAS No Load Operating Current VIN = 1.5V 70 VOUT = 1.2V 60 50 40 30 20 10 125°C –40°C 25°C 0 0.01 0.1 1 10 IOUT (mA) 100 1000 3025 G02 0 2.5 3 3.5 4.5 4 VBIAS (V) 5 5.5 3025 G03 VIN No Load Operating Current 14 12 10 IIN (μA) 8 6 4 2 0 0.5 VBIAS = 5V VOUT = 0.8V 7 6 125°C 85°C 25°C –40°C 2 IIN (μA) 5 4 3 VIN Shutdown Current VBIAS = 5V 405 404 403 ADJUST VOLTAGE (mV) 402 401 400 399 398 397 396 1.5 2.5 3.5 4.5 5.5 3025 G05 Adjust Voltage vs Temperature VBIAS = 3.6V VIN = 1.5V IOUT = 10μA –40°C 25°C 85°C 1 0 0.5 1.5 2.5 3.5 4.5 5.5 3025 G04 395 –50 –25 VIN (V) VIN (V) 50 25 0 75 TEMPERATURE (°C) 100 125 3025 G06 SHDN Threshold vs Temperature 1000 900 800 SHDN THRESHOLD (mV) 700 600 500 400 300 200 100 0 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 VBIAS = 2.5V VBIAS = 5V CURRENT LIMIT (mA) 1200 1000 800 600 400 200 0 1600 Current Limit vs VIN Voltage VBIAS = 3.6V 1400 VOUT = 0V VIN AC 100mV/DIV Burst Mode DC/DC Buck Ripple Rejection VOUT AC 10mV/DIV 0 1 2 3 VIN (V) 4 5 6 3025 G08 VIN = 1.8V VOUT = 1.5V COUT = 1μF IOUT = 50mA 10μs/DIV 3025 G09 3025 G07 3025fb 4 LTC3025 TYPICAL PERFORMANCE CHARACTERISTICS VIN Ripple Rejection vs Frequency 70 60 50 40 COUT = 1mF 30 20 10 REJECTION (dB) COUT = 10μF 70 60 50 40 30 COUT = 1mF 20 10 VBIAS = 3.6V VIN = 1.5V VOUT = 1.2V IOUT = 100mA 1k 10k 100k 1M 10M 3025 G11 BIAS Ripple Rejection vs Frequenc COUT = 10μF REJECTION (dB) 0 100 VBIAS = 3.6V VIN = 1.5V VOUT = 1.2V IOUT = 100mA 1k 10k 100k 1M 10M 3025 G10 0 100 FREQUENCY (Hz) FREQUENCY (Hz) 3MHz VIN Supply Rejection 50 45 40 REJECTION (dB) 35 30 25 20 15 10 5 VBIAS = 3.6V VOUT = 1.2V 0 1.2 1.4 1.6 IOUT = 100mA IOUT = 300mA 1.8 2.0 VIN (V) 2.2 2.4 2.6 VOUT AC 10mV/DIV COUT = 10μF COUT = 1μF 250mA IOUT 10mA Transient Response VIN = 1.5V VOUT = 1.2V VBIAS = 3.6V COUT = 1μF 100μs/DIV 3025 G13 3025 G12 3025fb 5 LTC3025 PIN FUNCTIONS BIAS (Pin 1): BIAS Input Voltage. BIAS provides internal power for LTC3025 circuitry. The BIAS pin should be locally bypassed to ground if the LTC3025 is more than a few inches away from another source of bulk capacitance. In general, the output impedance of a battery rises with frequency, so it is usually advisable to include an input bypass capacitor in battery-powered circuits. A capacitor in the range of 0.01μF to 0.1μF is usually sufficient. GND (Pin 2): Ground. Connect to a ground plane. IN (Pin 3): Input Supply Voltage. The output load current is supplied directly from IN. The IN pin should be locally bypassed to ground if the LTC3025 is more than a few inches away from another source of bulk capacitance. In general, the output impedance of a battery rises with frequency, so it is usually advisable to include an input bypass capacitor when supplying IN from a battery. A capacitor in the range of 0.1μF to 1μF is usually sufficient. OUT (Pin 4): Regulated Output Voltage. The OUT pin supplies power to the load. A minimum ceramic output capacitor of at least 1μF is required to ensure stability. Larger output capacitors may be required for applications with large transient loads to limit peak voltage transients. See the Applications Information section for more information on output capacitance. ADJ (Pin 5): Adjust Input. This is the input to the error amplifier. The ADJ pin reference voltage is 0.4V referenced to ground. The output voltage range is 0.4V to 3.6V and is typically set by connecting ADJ to a resistor divider from OUT to GND. See Figure 2. SHDN (Pin 6): Shutdown Input, Active Low. This pin is used to put the LTC3025 into shutdown. The SHDN pin current is typically less than 10nA. The SHDN pin cannot be left floating and must be tied to a valid logic level (such as BIAS) if not used. Exposed Pad (Pin 7): Ground and Heat Sink. Must be soldered to PCB ground plane or large pad for optimal thermal performance. BLOCK DIAGRAM 1 BIAS REFERENCE 6 SHDN SHDN 0.4V SOFT-START IN + – 6μA OUT ADJ 3 2 GND 4 5 3025 BD 3025fb 6 LTC3025 APPLICATIONS INFORMATION Operation (Refer to Block Diagram) The LTC3025 is a micropower, VLDO (very low dropout) linear regulator which operates from input voltages as low as 0.9V. The device provides a high accuracy output that is capable of supplying 300mA of output current with a typical dropout voltage of only 45mV. A single ceramic capacitor as small as 1μF is all that is required for output bypassing. A low reference voltage allows the LTC3025 output to be programmed to much lower voltages than available in common LDOs (range of 0.4V to 3. 6V). As shown in the Block Diagram, the BIAS input supplies the internal reference and LDO circuitry while all output current comes directly from the IN input for high efficiency regulation. The low quiescent supply currents IIN = 4μA, IBIAS = 50μA drop to IIN = 1μA, IBIAS = 0.01μA typical in shutdown making the LTC3025 an ideal choice for use in battery-powered systems. The device includes current limit and thermal overload protection. The fast transient response of the follower output stage overcomes the traditional tradeoff between dropout voltage, quiescent current and load transient response inherent in most LDO regulator architectures. The LTC3025 also includes overshoot detection circuitry which brings the output back into regulation when going from heavy to light output loads (see Figure 1). Adjustable Output Voltage The output voltage is set by the ratio of two external resistors as shown in Figure 2. The device servos the output to maintain the ADJ pin voltage at 0.4V (referenced to ground). Thus the current in R1 is equal to 0.4V/R1. For good transient response, stability, and accuracy, the current in R1 should be at least 8μA, thus the value of R1 should be no greater than 50k. The current in R2 is the current in R1 plus the ADJ pin bias current. Since the ADJ pin bias current is typically