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| LTC3108-1 Ultralow Voltage Step-Up Converter and Power Manager FeaTures n n DescripTion The LTC(R)3108-1 is a highly integrated DC/DC converter ideal for harvesting and managing surplus energy from extremely low input voltage sources such as TEGs (thermoelectric generators), thermopiles and small solar cells. The step-up topology operates from input voltages as low as 20mV. Using a small step-up transformer, the LTC3108-1 provides a complete power management solution for wireless sensing and data acquisition. The 2.2V LDO powers an external microprocessor, while the main output is programmed to one of four fixed voltages to power a wireless transmitter or sensors. The power good indicator signals that the main output voltage is within regulation. A second output can be enabled by the host. A storage capacitor provides power when the input voltage source is unavailable. Extremely low quiescent current and high efficiency design ensure the fastest possible charge times of the output reservoir capacitor. The LTC3108-1 is functionally equivalent to the LTC3108 except for its unique fixed VOUT options. The LTC3108-1 is available in a small, thermally enhanced 12-lead (3mm x 4mm) DFN package and a 16-lead SSOP package. n n n Operates from Inputs of 20mV Complete Energy Harvesting Power Management System - Selectable VOUT of 2.5V, 3V, 3.7V or 4.5V - LDO: 2.2V at 3mA - Logic Controlled Output - Reserve Energy Output Power Good Indicator Uses Compact Step-Up Transformers Small 12-Lead (3mm x 4mm) DFN or 16-Lead SSOP Packages applicaTions n n n n n n n Remote Sensors and Radio Power Surplus Heat Energy Harvesting HVAC Systems Industrial Wireless Sensing Automatic Metering Building Automation Predictive Maintenance L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical applicaTion Wireless Remote Sensor Application Powered From a Peltier Cell 1:100 + THERMOELECTRIC GENERATOR 20mV TO 500mV 1nF C1 330pF C2 SW VSTORE LTC3108-1 VOUT2 PGOOD PGD 2.2V VLDO 5.25V VOUT Charge Time 1000 0.1F 6.3V 100 TIME (sec) P 2.2F SENSORS VOUT = 3V COUT = 470F + + 220F 10 VS2 VOUT 3V + 470F RF LINK 1 1:100 Ratio 1:50 Ratio 1:20 Ratio 0 50 100 150 200 250 300 350 400 VIN (mV) 31081 TA01b VS1 VOUT2_EN VAUX GND 1F 31081 TA01a 0 31081f LTC3108-1 absoluTe MaxiMuM raTings (Note 1) SW Voltage ..................................................-0.3V to 2V C1 Voltage....................................................-0.3V to 6V C2 Voltage (Note 5).........................................-8V to 8V VOUT2, VOUT2_EN ...........................................-0.3V to 6V VAUX....................................................15mA into VAUX VS1, VS2, VAUX, VOUT, PGD ........................-0.3V to 6V VLDO, VSTORE ............................................-0.3V to 6V Operating Junction Temperature Range (Note 2)................................................. -40C to 125C Storage Temperature Range.................. -65C to 125C pin conFiguraTion TOP VIEW VAUX VSTORE VOUT VOUT2 VLDO PGD 1 2 3 4 5 6 13 GND 12 SW 11 C2 10 C1 9 8 7 VOUT2_EN VS1 VS2 GND VAUX VSTORE VOUT VOUT2 VLDO PGD GND 1 2 3 4 5 6 7 8 TOP VIEW 16 GND 15 SW 14 C2 13 C1 12 VOUT2_EN 11 VS1 10 VS2 9 GND DE PACKAGE 12-LEAD (4mm 3mm) PLASTIC DFN TJMAX = 125C, JA = 43C/W EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB (NOTE 4) GN PACKAGE 16-LEAD PLASTIC SSOP NARROW TJMAX = 125C, JA = 110C/W orDer inForMaTion LEAD FREE FINISH LTC3108EDE-1#PBF LTC3108IDE-1#PBF LTC3108EGN-1#PBF LTC3108IGN-1#PBF TAPE AND REEL LTC3108EDE-1#TRPBF LTC3108IDE-1#TRPBF LTC3108EGN-1#TRPBF LTC3108IGN-1#TRPBF PART MARKING* 31081 31081 31081 31081 PACKAGE DESCRIPTION 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 16-Lead Plastic SSOP 16-Lead Plastic SSOP TEMPERATURE RANGE -40C to 125C -40C to 125C -40C to 125C -40C to 125C Consult LTC Marketing for parts specified for other fixed output voltages or 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/ elecTrical characTerisTics PARAMETER Minimum Start-Up Voltage No-Load Input Current Input Voltage Range CONDITIONS The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are for TA = 25C (Note 2). VAUX = 5V, unless otherwise noted. MIN TYP 20 3 l MAX 50 UNITS mV mA Using 1:100 Transformer Turns Ratio, VAUX = 0V Using 1:100 Transformer Turns Ratio; VIN = 20mV, VOUT2_EN = 0V; All Outputs Charged and in Regulation Using 1:100 Transformer Turns Ratio VSTARTUP 500 mV 31081f LTC3108-1 elecTrical characTerisTics PARAMETER Output Voltage CONDITIONS VS1 = VS2 = GND VS1 = VAUX, VS2 = GND VS1 = GND, VS2 = VAUX VS1 = VS2 = VAUX VOUT = 3.7V, VOUT2_EN = 0V No Load, All Outputs Charged 0.5mA Load For 0mA to 2mA Load For VAUX from 2.5V to 5V IVLDO = 2mA VLDO = 0V VOUT = 0V VSTORE = 0V Current into VAUX = 5mA VSTORE = 5V VOUT2 = 0V, VOUT2_EN = 0V l l l l l l l l l l l The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are for TA = 25C (Note 2). VAUX = 5V, unless otherwise noted. MIN 2.45 2.94 3.626 4.41 TYP 2.50 3.00 3.70 4.50 0.2 6 2.134 2.2 0.5 0.05 100 4 2.8 2.8 5 11 4.5 4.5 5.25 0.1 0.1 0.4 0.85 0.01 -7.5 -9 0.15 2.1 l MAX 2.55 3.06 3.774 4.59 9 2.266 1 0.2 200 7 7 5.55 0.3 1.2 0.1 UNITS V V V V A A V % % mV mA mA mA V A A V A % % VOUT Quiescent Current VAUX Quiescent Current LDO Output Voltage LDO Load Regulation LDO Line Regulation LDO Dropout Voltage LDO Current Limit VOUT Current Limit VSTORE Current Limit VAUX Clamp Voltage VSTORE Leakage Current VOUT2 Leakage Current VS1, VS2 Threshold Voltage VS1, VS2 Input Current PGD Threshold (Rising) PGD Threshold (Falling) PGD VOL PGD VOH PGD Pull-Up Resistance VOUT2_EN Threshold Voltage VOUT2_EN Pull-Down Resistance VOUT2 Turn-On Time VOUT2 Turn-Off Time VOUT2 Current Limit VOUT2 Current Limit Response Time VOUT2 P-Channel MOSFET On-Resistance N-Channel MOSFET On-Resistance VS1 = VS2 = 5V Measured Relative to the VOUT Voltage Measured Relative to the VOUT Voltage Sink Current = 100A Source Current = 0 VOUT2_EN Rising 0.3 2.3 1.3 V V M V M s s 2.2 1 1 5 5 0.4 (Note 3) VOUT = 3.7V (Note 3) VOUT = 3.7V (Note 3) C2 = 5V (Note 3) l 0.15 0.15 0.3 350 1.3 0.5 0.45 A ns 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: The LTC3108-1 is tested under pulsed load conditions such that TJ TA. The LTC3108-1E is guaranteed to meet specifications from 0C to 85C junction temperature. Specifications over the -40C to 125C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LTC3108-1I is guaranteed over the full -40C to 125C operating junction temperature range. Note that the maximum ambient temperature is determined by specific operating conditions in conjunction with board layout, the rated thermal package thermal resistance and other environmental factors. The junction temperature (TJ) is calculated from the ambient temperature (TA) and power dissipation (PD) according to the formula: TJ = TA + (PD * JAC/W), where JA is the package thermal impedance. Note 3: Specification is guaranteed by design and not 100% tested in production. Note 4: Failure to solder the exposed backside of the package to the PC board ground plane will result in a thermal resistance much higher than 43C/W. Note 5: The absolute maximum rating is a DC rating. Under certain conditions in the applications shown, the peak AC voltage on the C2 pin may exceed 8V. This behavior is normal and acceptable because the current into the pin is limited by the impedance of the coupling capacitor. 31081f LTC3108-1 Typical perForMance characTerisTics 1000 TA = 25C, unless otherwise noted. IIN vs VIN, (VOUT = 0V) 1:50 RATIO, C1 = 4.7n 1:100 RATIO, C1 = 1n 1:20 RATIO, C1 = 10n IVOUT and Efficiency vs VIN, 1:20 Ratio Transformer 4000 3500 3000 C1 = 10nF IVOUT (VOUT = 0V) 80 70 60 EFFICIENCY (%) 50 EFFICIENCY (VOUT = 4V) IVOUT (VOUT = 4V) 40 30 20 10 0 100 200 300 400 0 500 31081 G01 100 IVOUT (A) 10 1 10 100 VIN (mV) 1000 31081 G00 2500 2000 1500 1000 500 0 IIN (mA) VIN (mV) IVOUT and Efficiency vs VIN, 1:50 Ratio Transformer 3200 2800 2400 IVOUT (A) 2000 1600 1200 800 400 0 0 100 200 300 400 EFFICIENCY (VOUT = 4V) IVOUT (VOUT = 4V) C1 = 4.7nF 80 IVOUT (VOUT = 0V) 70 60 EFFICIENCY (%) 50 40 30 20 10 0 500 31081 G02 IVOUT and Efficiency vs VIN, 1:100 Ratio Transformer 1400 1200 1000 IVOUT (A) 800 600 400 200 0 0 100 200 300 400 EFFICIENCY (VOUT = 4V) C1 = 1nF IVOUT (VOUT = 0V) 70 60 50 EFFICIENCY (%) 40 IVOUT (VOUT = 4V) 30 20 10 0 500 31081 G03 VIN (mV) VIN (mV) Input Resistance vs VIN (VOUT Charging) 10 9 8 INPUT RESISTANCE ( ) 7 6 5 4 3 2 1 0 0 100 200 300 400 500 31081 G04 IVOUT vs VIN and Source Resistance, 1:20 Ratio 10000 C1 = 10nF 1:20 RATIO 1000 IVOUT (A) 1:50 RATIO 100 1:100 RATIO 10 0 1 2 5 10 0 100 200 300 400 500 600 700 800 VIN OPEN-CIRCUIT (mV) 31081 G05 VIN (mV) 31081f LTC3108-1 Typical perForMance characTerisTics IVOUT vs VIN and Source Resistance, 1:50 Ratio 10000 C1 = 4.7nF 1000 TA = 25C, unless otherwise noted. IVOUT vs VIN and Source Resistance, 1:100 Ratio C1 = 1nF 1000 IVOUT (A) IVOUT (A) 100 100 10 0 1 2 5 10 0 100 200 300 400 500 600 700 800 VIN OPEN-CIRCUIT (mV) 31081 G06 10 1 2 5 10 0 100 200 300 400 VIN OPEN-CIRCUIT (mV) 500 31081 G07 IVOUT vs dT and TEG Size, 1:100 Ratio 10000 VOUT = 0V 40mm TEG 15mm TEG 100 C1 PIN 2V/DIV C2 PIN 2V/DIV SW PIN 50mV/ DIV Resonant Switching Waveforms VIN = 20mV 1:100 RATIO TRANSFORMER 1000 IVOUT (A) 10 0 0.1 1:50 RATIO 1:100 RATIO 1:50 RATIO 1:100 RATIO 10 1 dT ACROSS TEG (C) 100 31081 G08 10s/DIV 31081 G09 LDO Load Regulation 0.00 0.20 0.18 DROPOUT VOLTAGE (V) -0.25 DROP IN VLDO (%) 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 -1.00 0 0.5 1 1.5 2 2.5 LDO LOAD (mA) 3 3.5 4 0.00 LDO Dropout Voltage -0.50 -0.75 0 0.5 1 31081 G10 1.5 2 2.5 LDO LOAD (mA) 3 3.5 4 31081 G11 31081f LTC3108-1 Typical perForMance characTerisTics Start-Up Voltage Sequencing VIN = 50mV 1:100 RATIO TRANSFORMER COUT = 220F CSTORE = 470F CLDO = 2.2F TA = 25C, unless otherwise noted. VOUT and PGD Response During a Step Load 50mA LOAD STEP COUT = 220F CH1 VSTORE 1V/DIV CH2, VOUT 1V/DIV CH3, VLDO 1V/DIV CH2 VOUT, 1V/DIV CH1 PGD, 1V/DIV 10sec/DIV 31081 G12 5ms/DIV 31081 G13 VOUT Ripple 30A LOAD COUT = 220F VLDO 20mV/DIV LDO Step Load Response 20mV/ DIV ILDO 5mA/DIV 100ms/DIV 31081 G14 200s/DIV 0mA TO 3mA LOAD STEP CLDO = 2.2F 31081 G15 Enable Input and VOUT2 Running on Storage Capacitor CSTORE = 470F VOUT LOAD = 100A CH3 VSTORE 1V/DIV CH2, VOUT 1V/DIV CH4, VLDO 1V/DIV CH1, VIN 50mV/DIV VOUT2 1V/DIV CH2 CH1 VOUT2_EN 1V/DIV 1ms/DIV 10mA LOAD ON VOUT2 COUT = 220F 31081 G16 5sec/DIV 31081 G17 31081f LTC3108-1 pin FuncTions (DFN/SSOP) VAUX (Pin 1/Pin 2): Output of the Internal Rectifier Circuit and VCC for the IC. Bypass VAUX with at least 1F of capacitance. An active shunt regulator clamps VAUX to 5.25V (typical). VSTORE (Pin 2/Pin 3): Output for the Storage Capacitor or Battery. A large capacitor may be connected from this pin to GND for powering the system in the event the input voltage is lost. It will be charged up to the maximum VAUX clamp voltage. If not used, this pin should be left open or tied to VAUX. VOUT (Pin 3/Pin 4): Main Output of the Converter. The voltage at this pin is regulated to the voltage selected by VS1 and VS2 (see Table 1). Connect this pin to an energy storage capacitor or to a rechargeable battery. VOUT2 (Pin 4/Pin 5): Switched Output of the Converter. Connect this pin to a switched load. This output is open until VOUT2_EN is driven high, then it is connected to VOUT through a 1.3 P-channel switch. If not used, this pin should be left open or tied to VOUT. The peak current in this output is limited to 0.3A typical. VLDO (Pin 5/Pin 6): Output of the 2.2V LDO. Connect a 2.2F or larger ceramic capacitor from this pin to GND. If not used, this pin should be tied to VAUX. PGD (Pin 6/Pin 7): Power Good Output. When VOUT is within 7.5% of its programmed value, PGD will be pulled up to VLDO through a 1M resistor. If VOUT drops 9% below its programmed value PGD will go low. This pin can sink up to 100A. VS2 (Pin 7/Pin 10): VOUT Select Pin 2. Connect this pin to ground or VAUX to program the output voltage (see Table 1). VS1 (Pin 8/Pin 11): VOUT Select Pin 1. Connect this pin to ground or VAUX to program the output voltage (see Table 1). VOUT2_EN (Pin 9/Pin 12): Enable Input for VOUT2. VOUT2 will be enabled when this pin is driven high. There is an internal 5M pull-down resistor on this pin. If not used, this pin can be left open or grounded. C1 (Pin 10/Pin 13): Input to the Charge Pump and Rectifier Circuit. Connect a capacitor from this pin to the secondary winding of the step-up transformer. C2 (Pin 11/Pin 14): Input to the N-Channel Gate Drive Circuit. Connect a capacitor from this pin to the secondary winding of the step-up transformer. SW (Pin 12/Pin 15): Drain of the Internal N-Channel Switch. Connect this pin to the primary winding of the transformer. GND (Pins 1, 8, 9, 16) SSOP Only: Ground GND (Exposed Pad Pin 13) DFN Only: Ground. The DFN exposed pad must be soldered to the PCB ground plane. It serves as the ground connection, and as a means of conducting heat away from the die. Table 1. Regulated Voltage Using Pins VS1 and VS2 VS2 GND GND VAUX VAUX VS1 GND VAUX GND VAUX VOUT 2.5V 3V 3.7V 4.5V 31081f LTC3108-1 block DiagraM LTC3108-1 ILIM 1.3 VOUT2 VOUT2 VOUT2_EN SYNC RECTIFY C1 C1 5.25V C2 SW C2 SW VOUT VSTORE 0.5 CHARGE CONTROL REFERENCE 1.2V VREF 5M VOUT VOUT COUT OFF ON VIN CIN 1:100 + - VS1 VS2 VOUT PROGRAM VREF VLDO 1M - + VAUX 1F VOUT GND (SSOP) VBEST VREF LDO VLDO PGD PGOOD VSTORE CSTORE 31081 BD EXPOSED PAD (DFN) 2.2V 2.2F operaTion (Refer to the Block Diagram) The LTC3108-1 is designed to use a small external step-up transformer to create an ultralow input voltage step-up DC/DC converter and power manager. It is ideally suited for low power wireless sensors and other applications in which surplus energy harvesting is used to generate system power because traditional battery power is inconvenient or impractical. The LTC3108-1 is designed to manage the charging and regulation of multiple outputs in a system in which the average power draw is very low, but there may be periodic pulses of higher load current required. This is typical of wireless sensor applications, where the quiescent power draw is extremely low most of the time, except for transmit bursts when circuitry is powered up to make measurements and transmit data. The LTC3108-1 can also be used to trickle charge a standard capacitor, supercapacitor or rechargeable battery, using energy harvested from a Peltier or photovoltaic cell. 31081f LTC3108-1 operaTion Oscillator The LTC3108-1 utilizes a MOSFET switch to form a resonant step-up oscillator using an external step-up transformer and a small coupling capacitor. This allows it to boost input voltages as low as 20mV high enough to provide multiple regulated output voltages for powering other circuits. The frequency of oscillation is determined by the inductance of the transformer secondary winding and is typically in the range of 10kHz to 100kHz. For input voltages as low as 20mV, a primary-secondary turns ratio of about 1:100 is recommended. For higher input voltages, this ratio can be lower. See the Applications Information section for more information on selecting the transformer. Charge Pump and Rectifier The AC voltage produced on the secondary winding of the transformer is boosted and rectified using an external charge pump capacitor (from the secondary winding to pin C1) and the rectifiers internal to the LTC3108-1. The rectifier circuit feeds current into the VAUX pin, providing charge to the external VAUX capacitor and the other outputs. VAUX The active circuits within the LTC3108-1 are powered from VAUX, which should be bypassed with a 1F capacitor. Larger capacitor values are recommended when using turns ratios of 1:50 or 1:20 (refer to the Typical Application examples). Once VAUX exceeds 2.5V, the main VOUT is allowed to start charging. An internal shunt regulator limits the maximum voltage on VAUX to 5.25V typical. It shunts to GND any excess current into VAUX when there is no load on the converter or the input source is generating more power than is required by the load. Voltage Reference The LTC3108-1 includes a precision, micropower reference, for accurate regulated output voltages. This reference becomes active as soon as VAUX exceeds 2V. Synchronous Rectifiers Once VAUX exceeds 2V, synchronous rectifiers in parallel with each of the internal diodes take over the job of rectifying the input voltage, improving efficiency. Low Dropout Linear Regulator (LDO) The LTC3108-1 includes a low current LDO to provide a regulated 2.2V output for powering low power processors or other low power ICs. The LDO is powered by the higher of VAUX or VOUT. This enables it to become active as soon as VAUX has charged to 2.3V, while the VOUT storage capacitor is still charging. In the event of a step load on the LDO output, current can come from the main VOUT capacitor if VAUX drops below VOUT. The LDO requires a 2.2F ceramic capacitor for stability. Larger capacitor values can be used without limitation, but will increase the time it takes for all the outputs to charge up. The LDO output is current limited to 4mA minimum. VOUT The main output voltage on VOUT is charged from the VAUX supply, and is user programmed to one of four regulated voltages using the voltage select pins VS1 and VS2, according to Table 2. Although the logic threshold voltage for VS1 and VS2 is 0.85V typical, it is recommended that they be tied to ground or VAUX. Table 2. Regulated Voltage Using Pins VS1 and VS2 VS2 GND GND VAUX VAUX VS1 GND VAUX GND VAUX VOUT 2.5V 3V 3.7V 4.5V When the output voltage drops slightly below the regulated value, the charging current will be enabled as long as VAUX is greater than 2.5V. Once VOUT has reached the proper value, the charging current is turned off. The internal programmable resistor divider sets VOUT, eliminating the need for very high value external resistors that are susceptible to board leakage. 31081f LTC3108-1 operaTion In a typical application, a storage capacitor (typically a few hundred microfarads) is connected to VOUT. As soon as VAUX exceeds 2.5V, the VOUT capacitor will be allowed to charge up to its regulated voltage. The current available to charge the capacitor will depend on the input voltage and transformer turns ratio, but is limited to about 4.5mA typical. PGOOD A power good comparator monitors the VOUT voltage. The PGD pin is an open-drain output with a weak pull-up (1M) to the LDO voltage. Once VOUT has charged to within 7.5% of its regulated voltage, the PGD output will go high. If VOUT drops more than 9% from its regulated voltage, PGD will go low. The PGD output is designed to drive a microprocessor or other chip I/O and is not intended to drive a higher current load such as an LED. Pulling PGD up externally to a voltage greater than VLDO will cause a small current to be sourced into VLDO. PGD can be pulled low in a wire-OR configuration with other circuitry. VOUT2 VOUT2 is an output that can be turned on and off by the host, using the VOUT2_EN pin. When enabled, VOUT2 is connected to VOUT through a 1.3 P-channel MOSFET switch. This output, controlled by a host processor, can be used to power external circuits such as sensors and amplifiers, that do not have a low power sleep or shutdown capability. VOUT2 can be used to power these circuits only when they are needed. Minimizing the amount of decoupling capacitance on VOUT2 will allow it to be switched on and off faster, allowing shorter burst times and, therefore, smaller duty cycles in pulsed applications such as a wireless sensor/transmitter. A small VOUT2 capacitor will also minimize the energy that will be wasted in charging the capacitor every time VOUT2 is enabled. VOUT2 has a soft-start time of about 5s to limit capacitor charging current and minimize glitching of the main output when VOUT2 is enabled. It also has a current limiting circuit that limits the peak current to 0.3A typical. The VOUT2 enable input has a typical threshold of 1V with 100mV of hysteresis, making it logic-compatible. If VOUT2_EN (which has an internal pull-down resistor) is low, VOUT2 will be off. Driving VOUT2_EN high will turn on the VOUT2 output. Note that while VOUT2_EN is high, the current limiting circuitry for VOUT2 draws an extra 8A of quiescent current from VOUT. This added current draw has a negligible effect on the application and capacitor sizing, since the load on the VOUT2 output, when enabled, is likely to be orders of magnitude higher than 8A. VSTORE The VSTORE output can be used to charge a large storage capacitor or rechargeable battery after VOUT has reached regulation. Once VOUT has reached regulation, the VSTORE output will be allowed to charge up to the VAUX voltage. The storage element on VSTORE can be used to power the system in the event that the input source is lost, or is unable to provide the current demanded by the VOUT, VOUT2 and LDO outputs. If VAUX drops below VSTORE, the LTC3108-1 will automatically draw current from the storage element. Note that it may take a long time to charge a large capacitor, depending on the input energy available and the loading on VOUT and VLDO. Since the maximum current from VSTORE is limited to a few milliamps, it can safely be used to trickle-charge NiCd or NiMH rechargeable batteries for energy storage when the input voltage is lost. Note that the VSTORE capacitor cannot supply large pulse currents to VOUT. Any pulse load on VOUT must be handled by the VOUT capacitor. Short-Circuit Protection All outputs of the LTC3108-1 are current limited to protect against short-circuits to ground. Output Voltage Sequencing A timing diagram showing the typical charging and voltage sequencing of the outputs is shown in Figure 1. Note: time not to scale. 31081f 0 LTC3108-1 operaTion 5.0 2.5 0 3.0 2.0 1.0 0 VOLTAGE (V) 5.0 2.5 0 3.0 2.0 1.0 0 5.0 2.5 0 0 10 20 30 40 TIME (ms) 31081 F01a VSTORE (V) PGD (V) VOUT (V) VLDO (V) VAUX (V) 50 60 70 80 Figure 1. Output Voltage Sequencing with VOUT Programmed for 3V (Time Not to Scale) 31081f LTC3108-1 applicaTions inForMaTion Introduction The LTC3108-1 is designed to gather energy from very low input voltage sources and convert it to usable output voltages to power microprocessors, wireless transmitters and analog sensors. Such applications typically require much more peak power, and at higher voltages, than the input voltage source can produce. The LTC3108-1 is designed to accumulate and manage energy over a long period of time to enable short power bursts for acquiring and transmitting data. The bursts must occur at a low enough duty cycle such that the total output energy during the burst does not exceed the average source power integrated over the accumulation time between bursts. For many applications, this time between bursts could be seconds, minutes or hours. The PGD signal can be used to enable a sleeping microprocessor or other circuitry when VOUT reaches regulation, indicating that enough energy is available for a burst. Input Voltage Sources The LTC3108-1 can operate from a number of low input voltage sources, such as Peltier cells, photovoltaic cells or thermopile generators. The minimum input voltage required for a given application will depend on the transformer turns ratio, the load power required, and the internal DC resistance (ESR) of the voltage source. Lower ESR will allow the use of lower input voltages, and provide higher output power capability. 1000 Refer to the IIN vs VIN curves in the Typical Performance Characteristics section to see what input current is required for the source for a given input voltage. For a given transformer turns ratio, there is a maximum recommended input voltage to avoid excessively high secondary voltages and power dissipation in the shunt regulator. It is recommended that the maximum input voltage times the turns ratio be less than 50. Note that a low ESR bulk decoupling capacitor will usually be required across the input source to prevent large voltage droop and ripple caused by the source's ESR and the peak primary switching current (which can reach hundreds of milliamps). The time constant of the filter capacitor and the ESR of the voltage source should be much longer than the period of the resonant switching frequency. Peltier Cell (Thermoelectric Generator) A Peltier cell (also known as a thermoelectric cooler) is made up of a large number of series-connected P-N junctions, sandwiched between two parallel ceramic plates. Although Peltier cells are often used as coolers by applying a DC voltage to their inputs, they will also generate a DC output voltage, using the Seebeck effect, when the two plates are at different temperatures. The polarity of the output voltage will depend on the polarity of the temperature differential between the plates. The magnitude of the output voltage is proportional to the magnitude of the temperature differential between the plates. When used in 100 VOC TEG MAXIMUM POUT --IDEAL (mW) TEG: 30mm 127 COUPLES R=2 TEG VOPEN_CIRCUIT (mV) 100 10 10 MAX POUT (IDEAL) 1 1 1 10 dT (C) 0.1 100 31081 F02 Figure 2. Typical Performance of a Peltier Cell Acting as a Thermoelectric Generator 31081f LTC3108-1 applicaTions inForMaTion this manner, a Peltier cell is referred to as a thermoelectric generator (TEG). The low voltage capability of the LTC3108-1 design allows it to operate from a TEG with temperature differentials as low as 1C, making it ideal for harvesting energy in applications in which a temperature difference exists between two surfaces or between a surface and the ambient temperature. The internal resistance (ESR) of most cells is in the range of 1 to 5, allowing for reasonable power transfer. The curves in Figure 2 show the opencircuit output voltage and maximum power transfer for a typical Peltier cell (with an ESR of 2) over a 20C range of temperature differential. TEG Load Matching The LTC3108-1 was designed to present a minimum input resistance (load) in the range of 2 to 10, depending on input voltage and transformer turns ratio (as shown in the Typical Performance Characteristics curves). For a given turns ratio, as the input voltage drops, the input resistance increases. This feature allows the LTC3108-1 to optimize power transfer from sources with a few ohms of source resistance, such as a typical TEG. Note that a lower source resistance will always provide more output Table 4. Recommended TEG Part Numbers by Size MANUFACTURER CUI Inc. (Distributor) Ferrotec Fujitaka Kryotherm Laird Technology Marlow Industries Tellurex TE Technology C2-15-0405 TE-31-1.0-1.3 RC3-8-01 C2-20-0409 TE-31-1.4-1.15 15mm x 15mm CP60133 9501/031/030 B FPH13106NC 20mm x 20mm CP60233 9501/071/040 B FPH17106NC 30mm x 30mm CP60333 9500/097/090 B FPH17108AC TGM-127-1.0-0.8 PT6.7.F2.3030.W6 RC6-6-01 C2-30-1505 TE-71-1.4-1.15 40mm x 40mm CP85438 9500/127/100 B FPH112708AC LCB-127-1.4-1.15 PT8.12.F2.4040.TA.W6 RC12-8-01LS C2-40-1509 TE-127-1.4-1.05 current capability by providing a higher input voltage under load. Peltier Cell (TEG) Suppliers Peltier cells are available in a wide range of sizes and power capabilities, from less than 10mm square to over 50mm square. They are typically 2mm to 5mm in height. A list of Peltier cell manufacturers is given in Table 3. Table 3. Peltier Cell Manufacturers Fujitaka www.fujitaka.com/pub/peltier/english/thermoelectric_power.html FerroTec www.ferrotec.com/products/thermal/modules Laird Technologies www.lairdtech.com Marlow Industries www.marlow.com Micropelt www.micropelt.com Nextreme www.nextreme.com TE Technology www.tetech.com/Peltier-Thermoelectric-Cooler-Modules.html Tellurex www.tellurex.com Kryotherm www.kryothermusa.com 31081f LTC3108-1 applicaTions inForMaTion Thermopile Generator Thermopile generators (also called powerpile generators) are made up of a number of series-connected thermocouples enclosed in a metal tube. They are commonly used in gas burner applications to generate a DC output of hundreds of millivolts when exposed to the high temperature of a flame. Typical examples are the Honeywell CQ200 and Q313. These devices have an internal series resistance of less than 3, and can generate as much as 750mV open-circuit at their highest rated temperature. For applications in which the temperature rise is too high for a solid-state thermoelectric device, a thermopile can be used as an energy source to power the LTC3108-1. Because of the higher output voltages possible with a thermopile generator, a lower transformer turns ratio can be used (typically 1:20, depending on the application). Photovoltaic Cell The LTC3108-1 converter can also operate from a single photovoltaic cell (also known as a PV or solar cell) at light levels too low for other low input voltage boost converters to operate. However, many variables will affect the performance in these applications. Light levels can vary over several orders of magnitude and depend on lighting conditions (the type of lighting and indoor versus outdoor). Different types of light (sunlight, incandescent, fluorescent) also have different color spectra, and will produce different output power levels depending on which type of photovoltaic cell is being used (monocrystalline, polycrystalline or thin-film). Therefore, the photovoltaic cell must be chosen for the type and amount of light available. Note that the short-circuit output current from the cell must be at least a few milliamps in order to power the LTC3108-1 converter Non-Boost Applications The LTC3108-1 can also be used as an energy harvester and power manager for input sources that do not require boosting. In these applications the step-up transformer can be eliminated. Any source whose peak voltage exceeds 2.5V AC or 5V DC can be connected to the C1 input through a currentlimiting resistor where it will be rectified/peak detected. In 31081f these applications the C2 and SW pins are not used and can be grounded or left open. Examples of such input sources would be piezoelectric transducers, vibration energy harvesters, low current generators, a stack of low current solar cells or a 60Hz AC input. A series resistance of at least 100/V should be used to limit the maximum current into the VAUX shunt regulator. COMPONENT SELECTION Step-Up Transformer The step-up transformer turns ratio will determine how low the input voltage can be for the converter to start. Using a 1:100 ratio can yield start-up voltages as low as 20mV. Other factors that affect performance are the DC resistance of the transformer windings and the inductance of the windings. Higher DC resistance will result in lower efficiency. The secondary winding inductance will determine the resonant frequency of the oscillator, according to the following formula. Frequency = 1 2 * * L(sec)* C Hz Where L is the inductance of the transformer secondary winding and C is the load capacitance on the secondary winding. This is comprised of the input capacitance at pin C2, typically 30pF in parallel with the transformer secondary , winding's shunt capacitance. The recommended resonant frequency is in the range of 10kHz to 100kHz. See Table 5 for some recommended transformers. Table 5. Recommended Transformers VENDOR Coilcraft www.coilcraft.com PART NUMBER LPR6235-752SML (1:100 Ratio) LPR6235-253PML (1:20 Ratio) LPR6235-123QML (1:50 Ratio) LTC3108-1 applicaTions inForMaTion C1 Capacitor The charge pump capacitor that is connected from the transformer's secondary winding to the C1 pin has an effect on converter input resistance and maximum output current capability. Generally, a minimum value of 1nF is recommended when operating from very low input voltages using a transformer with a ratio of 1:100. Too large a capacitor value can compromise performance when operating at low input voltage or with high resistance sources. For higher input voltages and lower turns ratios, the value of the C1 capacitor can be increased for higher output current capability. Refer to the Typical Applications schematic examples for the recommended value for a given turns ratio. Squegging Certain types of oscillators, including transformer-coupled oscillators such as the resonant oscillator of the LTC3108-1, can exhibit a phenomenon called squegging. This term refers to a condition that can occur which blocks or stops the oscillation for a period of time much longer than the period of oscillation, resulting in bursts of oscillation. An example of this is the blocking oscillator, which is designed to squegg to produce bursts of oscillation. Squegging is also encountered in RF oscillators and regenerative receivers. In the case of the LTC3108-1, squegging can occur when a charge builds up on the C2 gate coupling capacitor, such that the DC bias point shifts and oscillation is extinguished for a certain period of time, until the charge on the capacitor bleeds off, allowing oscillation to resume. It is difficult to predict when and if squegging will occur in a given application. While squegging is not harmful, it reduces the average output current capability of the LTC3108-1. Squegging can easily be avoided by the addition of a bleeder resistor in parallel with the coupling capacitor on the C2 pin. Resistor values in the range of 100k to 1M are sufficient to eliminate squegging without having any negative impact on performance. For the 330pF capacitor used for C2 in most applications, a 499k bleeder resistor is recommended. See the Typical Applications schematics for an example. Using External Charge Pump Rectifiers The synchronous charge pump rectifiers in the LTC3108-1 (connected to the C1 pin) are optimized for operation from very low input voltage sources, using typical transformer step-up ratios between 1:100 and 1:50, and typical C1 charge pump capacitor values less than 10nF . Operation from higher input voltage sources (typically 250mV or greater, under load), allows the use of lower transformer step-up ratios (such as 1:20 and 1:10) and larger C1 capacitor values to provide higher output current capability from the LTC3108. However, due to the resulting increase in rectifier currents and resonant oscillator frequency in these applications, the use of external charge pump rectifiers is recommended for optimal performance. In applications where the step-up ratio is 1:20 or less, and the C1 capacitor is 10nF or greater, the C1 pin should be grounded and two external rectifiers (such as 1N4148 or 1N914 diodes) should be used. These are available as dual diodes in a single package. Avoid the use of Schottky rectifiers, as their lower forward-voltage drop increases the minimum startup voltage. See the Typical Applications schematics for an example. VOUT and VSTORE Capacitor For pulsed load applications, the VOUT capacitor should be sized to provide the necessary current when the load is pulsed on. The capacitor value required will be dictated by the load current, the duration of the load pulse, and the amount of voltage droop the circuit can tolerate. The capacitor must be rated for whatever voltage has been selected for VOUT by VS1 and VS2. COUT (F ) ILOAD(mA) * t PULSE (ms) VOUT ( V) Note that there must be enough energy available from the input voltage source for VOUT to recharge the capacitor during the interval between load pulses (to be discussed in the next example). Reducing the duty cycle of the load pulse will allow operation with less input energy. The VSTORE capacitor may be of very large value (thousands of microfarads or even Farads), to provide holdup 31081f LTC3108-1 applicaTions inForMaTion at times when the input power may be lost. Note that this capacitor can charge all the way to 5.25V (regardless of the settings for VOUT), so ensure that the holdup capacitor has a working voltage rating of at least 5.5V at the temperature for which it will be used. The VSTORE capacitor can be sized using the following: C STORE 6A + IQ + ILDO + (IBURST * t * f) * TSTORE 5 . 25 - VOUT PCB Layout Guidelines Due to the rather low switching frequency of the resonant converter and the low power levels involved, PCB layout is not as critical as with many other DC/DC converters. There are, however, a number of things to consider. Due to the very low input voltage the circuit may operate from, the connections to VIN, the primary of the transformer and the SW and GND pins of the LTC3108-1 should be designed to minimize voltage drop from stray resistance and able to carry currents as high as 500mA. Any small voltage drop in the primary winding conduction path will lower efficiency and increase capacitor charge time. Also, due to the low charge currents available at the outputs of the LTC3108-1, any sources of leakage current on the output voltage pins must be minimized. An example board layout is shown in Figure 3. VIN Where 6A is the quiescent current of the LTC3108-1, IQ is the load on VOUT in between bursts, ILDO is the load on the LDO between bursts, IBURST is the total load during the burst, t is the duration of the burst, f is the frequency of the bursts, TSTORE is the storage time required and VOUT is the output voltage required. To minimize losses and capacitor charge time, all capacitors used for VOUT and VSTORE should be low leakage. See Table 6 for recommended storage capacitors. Table 6. Recommended Storage Capacitors VENDOR AVX www.avx.com Cap-XX www.cap-xx.com Cooper/Bussmann www.bussmann.com/3/PowerStor.html Vishay/Sprague www.vishay.com/capacitors PART NUMBER/SERIES BestCap Series TAJ and TPS Series Tantalum GZ Series KR Series P Series Tantamount 592D 595D Tantalum 150CRZ/153CRV Aluminum 013 RLC (Low Leakage) VAUX VOUT VOUT2 VLDO PGOOD VSTORE VOUT VOUT2 VLDO PGD 1 2 3 4 5 6 12 11 10 9 8 7 SW C2 C1 VOUT2_EN VS1 VS2 Storage capacitors requiring voltage balancing are not recommended due to the current draw of the balancing resistors. GND 31081 FO3 VIAS TO GROUND PLANE Figure 3. Example Component Placement for Two-Layer PC Board (DFN Package) 31081f LTC3108-1 applicaTions inForMaTion Design Example 1 This design example will explain how to calculate the necessary storage capacitor value for VOUT in pulsed load applications, such as a wireless sensor/transmitter. In these types of applications, the load is very small for a majority of the time (while the circuitry is in a low power sleep state), with bursts of load current occurring periodically during a transmit burst. The storage capacitor on VOUT supports the load during the transmit burst, and the long sleep time between bursts allows the LTC3108-1 to recharge the capacitor. A method for calculating the maximum rate at which the load pulses can occur for a given output current from the LTC3108-1 will also be shown. In this example, VOUT is set to 3V, and the maximum allowed voltage droop during a transmit burst is 10%, or 0.3V. The duration of a transmit burst is 1ms, with a total average current requirement of 40mA during the burst. Given these factors, the minimum required capacitance on VOUT is: COUT (F ) 40mA * 1ms = 133 F 0 . 3V since there are many factors affecting the efficiency of the converter. Also determine what the total load current is on VOUT during the sleep state (between bursts). Note that this must include any losses, such as storage capacitor leakage. Assume, for instance, that the charge current from the LTC3108-1 is 50A and the total current drawn on VOUT in the sleep state is 17A, including capacitor leakage. In addition, use the value of 150F for the VOUT capacitor. The maximum transmit rate (neglecting the duration of the transmit burst, which is typically very short) is then given by: t= 150 F * 0 . 3V = 1 . 36 sec or f MAX = 0 . 73Hz (50 A - 17A) Therefore, in this application example, the circuit can support a 1ms transmit burst every 1.3 seconds. It can be determined that for systems that only need to transmit every few seconds (or minutes or hours), the average charge current required is extremely small, as long as the sleep current is low. Even if the available charge current in the example above was only 10A and the sleep current was only 5A, it could still transmit a burst every 9 seconds. The following formula enables the user to calculate the time it will take to charge the LDO output capacitor and the VOUT capacitor the first time, from 0V. Here again, the charge current available from the LTC3108-1 must be known. For this calculation, it is assumed that the LDO output capacitor is 2.2F . 2 . 2V * 2 . 2 F t LDO = ICHG - ILDO If there were 50A of charge current available and a 5A load on the LDO (when the processor is sleeping), the time for the LDO to reach regulation would be 107ms. If VOUT were programmed to 3V and the VOUT capacitor was 150F the time for VOUT to reach regulation would be: , 3V * 150 F t VOUT = +t ICHG - I VOUT - ILDO LDO 31081f Note that this equation neglects the effect of capacitor ESR on output voltage droop. For most ceramic or low ESR tantalum capacitors, the ESR will have a negligible effect at these load currents. A standard value of 150F or larger could be used for COUT in this case. Note that the load current is the total current draw on VOUT, VOUT2 and VLDO, since the current for all of these outputs must come from VOUT during a burst. Current contribution from the holdup capacitor on VSTORE is not considered, since it may not be able to recharge between bursts. Also, it is assumed that the charge current from the LTC3108-1 is negligible compared to the magnitude of the load current during the burst. To calculate the maximum rate at which load bursts can occur, determine how much charge current is available from the LTC3108-1 VOUT pin given the input voltage source being used. This number is best found empirically, LTC3108-1 applicaTions inForMaTion If there were 50A of charge current available and 5A of load on VOUT, the time for VOUT to reach regulation after the initial application of power would be 11.35 seconds. Design Example 2 In many pulsed load applications, the duration, magnitude and frequency of the load current bursts are known and fixed. In these cases, the average charge current required from the LTC3108-1 to support the average load must be calculated, which can be easily done by the following: ICHG IQ + IBURST * t T In this example, IQ = 5A, IBURST = 100mA, t = 5ms and T = one hour. The average charge current required from the LTC3108-1 would be: ICHG 5A + 100 mA * 0 . 005 sec = 5 . 14 A 3600 sec Where IQ is the sleep current on VOUT required by the external circuitry in between bursts (including cap leakage), IBURST is the total load current during the burst, t is the duration of the burst and T is the period of the transmit burst rate (essentially the time between bursts). Therefore, if the LTC3108-1 has an input voltage that allows it to supply a charge current greater than 5.14A, the application can support 100mA bursts lasting 5ms every hour. It can be determined that the sleep current of 5A is the dominant factor because the transmit duty cycle is so small (0.00014%). Note that for a VOUT of 3V, the average power required by this application is only 15.4W (not including converter losses). Note that the charge current available from the LTC3108-1 has no effect on the sizing of the VOUT capacitor (if it is assumed that the load current during a burst is much larger than the charge current), and the VOUT capacitor has no effect on the maximum allowed burst rate. Typical applicaTions Peltier-Powered Energy Harvester for Remote Sensor Applications + THERMOELECTRIC GENERATOR 1:100 T1 1nF C1 330pF C2 VSTORE VOUT2 LTC3108-1 PGD VLDO 5.25V + + CIN COOPER BUSSMAN PB-5ROH104-R OR KR-5R5H104-R CSTORE 0.1F 3V 6.3V VOUT2 SENSORS PGOOD 2.2V 2.2F P T = 1C TO 20C 499k XMTR SW VS2 VS1 VAUX T1: COILCRAFT LPR6235-752SML *COUT VALUE DEPENDENT ON THE MAGNITUDE AND DURATION OF THE LOAD PULSE 1F VOUT 3V + COUT* VOUT2_EN GND OFF ON 31081 TA02 31081f LTC3108-1 Typical applicaTions Supercapacitor Charger and LDO Powered by a Solar Cell (Uses External Charge Pump Rectifiers) 0.022F BAS31 VAUX 10,000 T1 1:20 INCANDESCENT LIGHT C1 330pF VSTORE 1000 IVOUT (A) OUTDOOR LIGHT (CLOUDY) 100 IVOUT vs Illuminance (2" Diameter Monocrystalline Cell) + SOLAR CELL* + - 220F VOUT2 LTC3108-1 PGD C2 VLDO VOUT SW VS2 VS1 VAUX VOUT2_EN GND 4.7F 31081 TA03 2.2V 3.0V 499k VLDO + VOUT 2.2F 4F* FLOURESCENT LIGHT 10 100 1000 10,000 ILLUMINANCE (LUX) 10,0000 31081 TA03b * 2" DIAMETER MONOCRYSTALLINE CELL LIGHT LEVEL 900 LUX T1: COILCRAFT LPR6235-253PML VAUX *TAIYO YUDEN PAS1020LA3R0405 Dual Output Converter and LDO Powered by a Thermopile Generator HONEYWELL Q313 THERMOPILE T1 1:50 4.7nF C1 330pF C2 499k VLDO SW VS2 VS1 VAUX 2.2F 31081 TA04 + VSTORE VOUT2 LTC3108-1 PGD PGOOD 2.2V 4.5V 220F VLDO 2.2F VOUT VOUT2_EN GND + VOUT 150F 6.3V T1: COILCRAFT LPR6235-123QML 31081f LTC3108-1 Typical applicaTions DC Input Energy Harvester and Power Manager RIN RIN > 100 / V C1 VSTORE VOUT2 5.25V VOUT2 PGOOD + - + VIN VIN > 5V C2 SW VS2 LTC3108-1 CSTORE PGD VLDO VOUT 2.2V 3V VLDO 2.2F + VOUT COUT VS1 VAUX 2.2F VOUT2_EN GND 31081 TA05 VOUT2_ENABLE AC Input Energy Harvester and Power Manager RIN CIN RIN > 100 / V AC VIN VIN > 5VP-P - PIEZO - 60Hz C2 SW VS2 VS1 VAUX 2.2F VOUT2_EN GND 31081 TA06 C1 VSTORE VOUT2 PGD LTC3108-1 VLDO VOUT 5.25V VOUT2 PGOOD + CSTORE 2.2V 4.5V VLDO 2.2F + VOUT COUT VOUT2_ENABLE 31081f 0 LTC3108-1 Typical applicaTions Low Profile (1.5mm) Step-Up Converter/Harvester Using 1:10 Transformer VSTORE VIN 150mV TO 600mV CIN T1 1:10 CRES* 390pF VOUT2 499k C1 C2 LTC3108-1 PGD VLDO PGOOD 2.2V VLDO 2.2F SW VS2 0.068F VS1 T1: COILCRAFT LPR4012-202LML *CRES LOWERS START-UP VOLTAGE TO 135mV TYPICAL OUTPUT CAN SUPPORT A 20mA, 10ms LOAD PULSE EVERY 0.4s AT VIN = 150mV BAS31 VAUX VAUX 10F VOUT2_EN GND VOUT 3V VOUT2 0.1F 3V AT 20mA 10ms 330pF + 330F 3 AVX TPSX337M004R0100 2.2V OFF ON 10ms ENABLE 31081 TA07 IVOUT vs VIN (Steady State) 6 5 4 IVOUT (mA) 3 2 1 0 150 200 250 300 350 400 450 500 550 600 VIN (mV) 31081 TA07b VOUT 3V TYPICAL MINIMUM LIMIT 31081f LTC3108-1 package DescripTion UE/DE Package 12-Lead Plastic DFN (4mm x 3mm) (Reference LTC DWG # 05-08-1695) 0.70 0.05 3.30 0.05 1.70 0.05 PACKAGE OUTLINE 0.25 0.05 2.50 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 0.10 (2 SIDES) R = 0.05 TYP 3.00 0.10 (2 SIDES) 3.30 0.10 1.70 0.10 PIN 1 NOTCH R = 0.20 OR 0.35 45 CHAMFER (UE12/DE12) DFN 0806 REV D 3.60 0.05 2.20 0.05 0.50 BSC 7 R = 0.115 TYP 0.40 12 0.10 PIN 1 TOP MARK (NOTE 6) 0.200 REF 0.75 0.05 6 0.25 0.05 2.50 REF 1 0.50 BSC 0.00 - 0.05 BOTTOM VIEW--EXPOSED PAD NOTE: 1. DRAWING PROPOSED TO BE A VARIATION OF VERSION (WGED) IN JEDEC PACKAGE OUTLINE M0-229 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 31081f LTC3108-1 package DescripTion GN Package 16-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641) .045 .005 .189 - .196* (4.801 - 4.978) 16 15 14 13 12 11 10 9 .009 (0.229) REF .254 MIN .150 - .165 .229 - .244 (5.817 - 6.198) .0165 .0015 .0250 BSC .150 - .157** (3.810 - 3.988) RECOMMENDED SOLDER PAD LAYOUT 1 .015 .004 x 45 (0.38 0.10) .007 - .0098 (0.178 - 0.249) 0 - 8 TYP .0532 - .0688 (1.35 - 1.75) 23 4 56 7 8 .004 - .0098 (0.102 - 0.249) .016 - .050 (0.406 - 1.270) NOTE: 1. CONTROLLING DIMENSION: INCHES INCHES 2. DIMENSIONS ARE IN (MILLIMETERS) 3. DRAWING NOT TO SCALE *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE .008 - .012 (0.203 - 0.305) TYP .0250 (0.635) BSC GN16 (SSOP) 0204 31081f Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. LTC3108-1 Typical applicaTion Dual TEG Energy Harvester Operates from Temperature Differentials of Either Polarity HOT THERMOELECTRIC GENERATOR COLD 499k LPR6235-752SML 1:100 + TEC 330pF C2 SW VS2 VS1 VAUX 1F 1nF C1 330pF C2 499k LPR6235-752SML SW VS2 VS1 VAUX VAUX VSTORE VOUT2 LTC3108-1 PGD VLDO VOUT VOUT2_EN GND 31081 TA08 1nF C1 VSTORE VOUT2 LTC3108-1 PGD VLDO VOUT2_EN GND OFF ON VOUT 5.25V VOUT2 PGOOD 3V + CSTORE 2.2V VLDO 2.2F + VOUT COUT COLD THERMOELECTRIC GENERATOR HOT 1:100 + TEC relaTeD parTs PART NUMBER LTC3108 LTC4070 LTC1041 LTC1389 LT1672/LT1673/ LT1674 LT3009 LTC3525L-3/ LTC3525L-3.3/ LTC3525L-5 LTC3588-1 LTC3632 LTC3642 LT8410/ LT8410-1 THERMOELECTRIC GENERATOR DESCRIPTION COMMENTS Ultralow Voltage Step-Up Converter and Power Manager VIN: 0.02V to 1V; VOUT = 2.35V, 3.3V, 4.1V, 5V Fixed; IQ = 6A; ISD <1A; 3mm x 4mm DFN-12 and SSOP-16 Packages Li-Ion/Polymer Low Current Shunt Battery Charger System Bang-Bang Controller Nanopower Precision Shunt Voltage Reference Single-/Dual-/Quad-Precision 2A Rail-to-Rail Op Amps 3A IQ, 20mA Linear Regulator 400mA (ISW), Synchronous Step-Up DC/DC Converter with Output Disconnect Piezoelectric Energy Generator with Integrated High Efficiency Buck Converter 45V, 20mA Synchronous MicroPower Buck Converter 45V, 50mA Synchronous MicroPower Buck Converter MicroPower 25mA/8mA Low Noise Boost Converter with Integrated Schottky Diode and Output Disconnect VIN: 450nA to 50mA; VOUT(MIN): VFLOAT + 4V, 4.1V, 4.2V; IQ = 300nA; 2mm x 3mm DFN-8 and MSOP-8 Packages VIN: 2.8V to 16V; VOUT(MIN) = Adj; IQ = 1.2mA; ISD < 1A; SO-8 Package VOUT(MIN) = 1.25V; IQ = 0.8A; SO-8 Package SO-8, SO-14 and MSOP-8 Packages VIN: 1.6V to 20V; VOUT(MIN): 0.6V to Adj, 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, 5V to Fixed; IQ = 3A; ISD < 1A; 2mm x 2mm DFN-8 and SC70 Packages VIN: 0.7V to 4V; VOUT(MIN) = 5VMAX; IQ = 7A; ISD < 1A; SC70 Package VIN: 2.7V to 20V; VOUT(MIN): Fixed to 1.8V, 2.5V, 3.3V, 3.6V; IQ = 0.95A; 3mm x 3mm DFN-10 and MSOP-10E Packages VIN: 4.5V to 45V, 60VMAX; VOUT(MIN): 0.8V to Adj, 3.3V Fixed, 5V Fixed; IQ = 12A; ISD < 1A; 3mm x 3mm DFN-8 and MSOP-8E Packages VIN: 4.5V to 45V, 60VMAX; VOUT(MIN): 0.8V to Adj, 3.3V Fixed, 5V Fixed; IQ = 12A; ISD < 1A; 3mm x 3mm DFN-8 and MSOP-8E Packages VIN: 2.6V to 16V; VOUT(MIN) = 40VMAX; IQ = 8.5A; ISD < 1A; 2mm x 2mm DFN-8 Package 31081f LT 0410 * PRINTED IN USA Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com LINEAR TECHNOLOGY CORPORATION 2010 |
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