AS1310 Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter General Description The AS1310 is an ultra low quiescent current hysteretic step-up DC-DC converter optimized for light loads (60mA), where it achieves efficiencies of up to 92%. AS1310 operates from a 0.7V to 3.6V supply and supports output voltages between 1.8V and 3.3V. Besides the available AS1310 standard variants any variant with output voltages in 50mV steps are available. If the input voltage exceeds the output voltage the device is in a feed-through mode and the input is directly connected to the output voltage. In light load operation, the device enters a sleep mode when most of the internal operating blocks are turned OFF in order to save power. This mode is active approximately 50s after a current pulse provided that the output is in regulation. In order to save power the AS1310 features a shutdown mode, where it draws less than 100nA. During shutdown mode the battery is disconnected from the output. The AS1310 also offers adjustable low battery detection. If the battery voltage decreases below the threshold defined by two external resistors on pin LBI, the LBO output is pulled to logic low. The AS1310 is available in a TDFN (2x2) 8-pin package. Ordering Information and Content Guide appear at end of datasheet. Key Benefits & Features The benefits and features of AS1310, Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter are listed below: Figure 1: Added Value of Using AS1310 Benefits Features Ideal for single Li-Ion battery powered applications * Wide Input Voltage Range (0.7V to 3,6V) * Feed through mode when VIN > VOUT Extended battery life * High Efficiency up to 92% * Low Quiescent Current of typ. 1uA * Low Shutdown Current of less than 100nA Supports a variety of end applications * Fixed output voltage range (1.8V to 3.3V) * Output Disconnect in shutdown * Output current: 60mA @ VIN=0.9V, VOUT=1.8V ams Datasheet [v1-11] 2015-Jan-28 Page 1 Document Feedback AS1310 - General Description Benefits Features Over - temperature protection and shutdown Integrated temperature monitoring Early power-fail warning Adjustable low battery detection * No external diode or transistor required * 8-pin TDFN (2mm x 2mm) Cost effective, small package Applications The AS1310 is an ideal solution for single and dual cell powered devices as blood glucose meters, remote controls, hearing aids, wireless mouse or any light-load application. Figure 2: Typical Application Diagram L1 6.8H 3 VIN 0.7V to 3.6V C1 22F 8 VIN 1 LBI On Off Low Battery Detect 6 LBO R1 R2 AS1310 R3 VOUT 1.8V to 3.3V 4 VOUT C2 22F 5 7 REF EN 2 Page 2 Document Feedback LX CREF 100nF GND ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Pin Assignment Pin Assignment Figure 3: Pin Diagram (Top View) LBI 1 8 VIN GND 2 7 EN 6 LBO 5 REF AS1310 LX 3 VOUT 4 Exposed pad Figure 4: Pin Description Pin Number Pin Name Description 1 LBI Low Battery Comparator Input. 0.6V Threshold. May not be left floating. If connected to GND, LBO is working as Power Output OK. 2 GND 3 LX 4 VOUT Output Voltage. Decouple VOUT with a ceramic capacitor as close as possible to VOUT and GND. 5 REF Reference Pin. Connect a 100nF ceramic capacitor to this pin. 6 LBO Low Battery Comparator Output. Open-drain output. 7 EN Enable Pin. Logic controlled shutdown input. 1 = Normal operation; 0 = Shutdown; shutdown current <100nA. 8 VIN Battery Voltage Input. Decouple VIN with a 22F ceramic capacitor as close as possible to VIN and GND. 9 NC Exposed Pad. This pad is not connected internally. Can be left floating or connect to GND to achieve an optimal thermal performance. ams Datasheet [v1-11] 2015-Jan-28 Ground External Inductor Connector Page 3 Document Feedback AS1310 - Absolute Maximum Ratings Absolute Maximum Ratings Stresses beyond those listed in Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in Electrical Characteristics is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Figure 5: Absolute Maximum Ratings Parameter Min Max Units Comments Electrical Parameters VIN, VOUT, EN, LBI, LBO to GND -0.3 +5 V LX, REF to GND -0.3 VOUT + 0.3 V Input Current (latch-up immunity) -100 100 mA Norm: JEDEC 78 Electrostatic Discharge Electrostatic Discharge HBM 2 kV Norm: MIL 883 E method 3015 Temperature Ranges and Storage Conditions Thermal Resistance JA 58 Junction Temperature Storage Temperature Range -55 Package Body Temperature Humidity non-condensing Moisture Sensitive Level Page 4 Document Feedback 5 1 C/W +125 C +125 C +260 C 85 % The reflow peak soldering temperature (body temperature) specified is in accordance with IPC/JEDEC J-STD-020"Moisture/Reflow Sensitivity Classification for Non-Hermetic Solid State Surface Mount Devices". The lead finish for Pb-free leaded packages is matte tin (100% Sn). Represents a maximum floor life time of unlimited ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Electrical Characteristics Electrical Characteristics All limits are guaranteed. The parameters with Min and Max values are guaranteed by production tests or SQC (Statistical Quality Control) methods. VIN = 1.5V, C1 = C2 = 22F, C REF = 100nF, Typical values are at TAMB = +25C (unless otherwise specified). All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality Control) methods. Figure 6: Electrical Characteristics Symbol TAMB Parameter Conditions Max Units -40 +85 C 0.7 3.6 V 0.8 V 1.8 3.3 V ILOAD = 10 mA, TAMB = +25C -2 +2 % ILOAD = 10mA -3 +3 % 1.75 V 100 nA 1.2 A 100 nA Operating Temperature Range Min Typ Input VIN Input Voltage Range Minimum Startup Voltage ILOAD = 1mA, TAMB = +25C 0.7 Regulation VOUT Output Voltage Range Output Voltage Tolerance VOUT Lockout Threshold(1) Rising Edge 1.55 1.65 Operating Current Quiescent Current VIN VOUT = 1.02xVOUTNOM, REF = 0.99xVOUTNOM, TAMB = +25C Quiescent Current VOUT VOUT = 1.02xVON, REF = 0.99xVON, No load, TAMB = +25C Shutdown Current TAMB = +25C IQ ISHDN ams Datasheet [v1-11] 2015-Jan-28 0.8 1 Page 5 Document Feedback AS1310 - Electrical Characteristics Symbol Parameter Conditions Min Typ Max Units Switches NMOS PMOS IPEAK 0.35 0.5 VOUT = 3V RON NMOS maximum On-time 3.6 4.2 4.8 s Peak Current Limit 320 400 480 mA 5 20 35 mA Zero Crossing Current Enable, Reference VENH EN Input Voltage High VENL EN Input Voltage Low IEN EN Input Bias Current IREF REF Input Bias Current 0.7 V 0.1 V EN = 3.6V, TAMB = +25C 100 nA REF = 0.99xVOUTNOM, TAMB = +25C 100 nA 0.63 V Low Battery & Power-OK VLBI LBI Threshold Falling Edge 0.57 LBI Hysteresis 0.6 25 ILBI LBI Leakage Current LBI = 3.6V, TAMB = +25C VLBO LBO Voltage Low (2) ILBO = 1mA ILBO LBO Leakage Current LBO = 3.6V, TAMB = +25C Power-OK Threshold LBI = 0V, Falling Edge 20 90 92.5 mV 100 nA 100 mV 100 nA 95 % Thermal Protection Thermal Shutdown 10C Hysteresis 150 C Note(s) and/or Footnote(s): 1. The regulator is in startup mode until this voltage is reached. Caution: Do not apply full load current until the device output > 1.75V. 2. LBO goes low in startup mode as well as during normal operation if: - The voltage at the LBI pin is below LBI threshold. - The voltage at the LBI pin is below 0.1V and V OUT is below 92.5% of its nominal value. Page 6 Document Feedback ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Typical Operating Characteristics Typical Operating Characteristics TAMB = +25C, unless otherwise specified. Figure 7: Efficiency vs. Output Current; VOUT = 1.8V 90 L1: XPL2010-682M 85 Efficiency (%) 80 75 70 65 60 55 50 Vin = 0.9V Vin = 1.2V 45 Vin = 1.5V 40 0.01 0.1 1 10 100 1000 Output Current (mA) Figure 8: Efficiency vs. Output Current; VOUT = 1.8V 90 85 L1: XPL7030-682M Efficiency (%) 80 75 70 65 60 55 50 Vin = 0.9V Vin = 1.2V 45 40 0.01 Vin = 1.5V 0.1 1 10 100 1000 Output Current (mA) ams Datasheet [v1-11] 2015-Jan-28 Page 7 Document Feedback AS1310 - Typical Operating Characteristics Figure 9: Efficiency vs. Output Current; VOUT = 3.0V 100 95 L1: XPL2010-682M Efficiency (%) 90 85 80 75 70 65 60 Vin = 0.9V 55 50 Vin = 1.2V Vin = 1.5V Vin = 1.8V 45 Vin = 2.4V 40 0.01 0.1 1 10 100 1000 Output Current (mA) Figure 10: Efficiency vs. Output Current; VOUT = 3.0V 100 95 L1: XPL7030-682M Efficiency (%) 90 85 80 75 70 65 60 Vin = 0.9V 55 50 Vin = 1.2V Vin = 1.5V Vin = 1.8V 45 40 0.01 Vin = 2.4V 0.1 1 10 100 1000 Output Current (mA) Page 8 Document Feedback ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Typical Operating Characteristics Figure 11: Efficiency vs. Input Voltage; VOUT = 1.8V 100 L1: XPL2010-682M 95 Efficiency (%) 90 85 80 75 70 65 60 Iout = 1mA Iout=10mA 55 Iout=50mA 50 0.7 0.9 1.1 1.3 1.5 1.7 1.9 Input Voltage (V) Figure 12: Maximum Output Current vs. Input Voltage 180 Output Current (mA) . 160 140 120 100 80 60 40 Vout = 1.8V 20 Vout = 3.0V 0 0 0.5 1 1.5 2 2.5 3 Input Voltage (V) ams Datasheet [v1-11] 2015-Jan-28 Page 9 Document Feedback AS1310 - Typical Operating Characteristics Figure 13: Start-up Voltage vs. Output Current 1 Start-up Voltage (V) 0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5 0 1 2 3 4 5 6 7 8 9 10 Output Current (mA) Figure 14: RON vs. Temperature 1 0.9 0.8 0.7 R ON () 0.6 0.5 0.4 0.3 0.2 PM OS 0.1 0 -40 NM OS -15 10 35 60 85 Temperature (C) Page 10 Document Feedback ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Typical Operating Characteristics 100mV/Div VOUT (AC) ILX 200mA/Div VLX 2V/Div Figure 15: Output Voltage Ripple; VIN = 2V, VOUT = 3V,Rload = 100 5s/Div ams Datasheet [v1-11] 2015-Jan-28 Page 11 Document Feedback AS1310 - Detailed Description Detailed Description Hysteretic Boost Converter Hysteretic boost converters are so called because comparators are the active elements used to determine ON-OFF timing via current and voltage measurements. There is no continuously operating fixed oscillator, providing an independent timing reference. As a result, a hysteretic or comparator based converter has a very low quiescent current. In addition, because there is no fixed timing reference, the operating frequency is determined by external component (inductor and capacitors) and also the loading on the output. Ripple at the output is an essential operating component. A power cycle is initiated when the output regulated voltage drops below the nominal value of VOUT (0.99 x V OUT ). Inductor current is monitored by the control loop, ensuring that operation is always dis-continuous. The application circuit shown in Figure 2 will support many requirements. However, further optimization may be useful, and the following is offered as a guide to changing the passive components to more closely match the end requirement. Input Loop Timing The input loop consists of the source DC supply, the input capacitor, the main inductor, and the N-channel power switch. The ON timing of the N-channel switch is determined by a peak current measurement or a maximum ON time. In the AS1310, peak current is 400mA (typ) and maximum ON time is 4.2s (typ). Peak current measurement ensures that the ON time varies as the input voltage varies. This imparts line regulation to the converter. The fixed ON-time measurement is something of a safety feature to ensure that the power switch is never permanently ON. The fixed on-time is independent of input voltage changes. As a result, no line regulation exists. Page 12 Document Feedback ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Detailed Description Figure 16: Simplified Boost DCDC Architecture L1 SW2 VIN VOUT Q CIN SW1 Q FB COUT RLOAD IPK GND 0V 0V ON time of the power switch (Faraday's Law) is given by: (EQ1) LI PK T ON = -------------------------------------------------------------------- sec [volts, amps, ohms, Henry] V IN - ( I PK R SW1 + I PK R L1 ) Applying Min and Max values and neglecting the resistive voltage drop across L1 and SW1; (EQ2) (EQ3) ams Datasheet [v1-11] 2015-Jan-28 TON _ MIN = TON _ MAX = LMIN I PK _ MIN V IN _ MAX LMAX I PK _ MAX V IN _ MIN Page 13 Document Feedback AS1310 - Detailed Description Figure 17: Simplified Voltage and Current Waveforms V 0.99VOUT_NOM VOUT Ripple VOUT VIND_TOFF B B VIN VIND_TON C D A C D 0 T TOFF IL TWAIT TON SW1_on SW2_off TOFF TWAIT IPK 0 SW2_on SW1_off T T T Another important relationship is the "volt-seconds" law. Expressed as following: (EQ4) V ON T ON = V OFF T OFF Voltages are those measured across the inductor during each time segment. Figure 17 shows this graphically with the shaded segments marked "A & B". Re-arranging EQ 4: (EQ5) T ON V OUT - V IN ------------ = ----------------------------V IN T OFF The time segment called T WAIT in Figure 17 is a measure of the "hold-up" time of the output capacitor. While the output voltage is above the threshold (0.99xV OUT ), the output is assumed to be in regulation and no further switching occurs. Page 14 Document Feedback ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Detailed Description Inductor Choice Example For the AS1310 V IN_MIN = 0.9V, V OUT_MAX = 3.3V, EQ 5 gives TON=2.66TOFF. Let the maximum operating on-time = 1s. Note that this is shorter than the minimum limit ON-time of 3.6s. Therefore from EQ 5, TOFF = 0.376s. Using EQ 3, L MAX is obtained: LMAX = 1.875H. The nearest preferred value is 2.2H. This value provides the maximum energy storage for the chosen fixed ON-time limit at the minimum V IN. Energy stored during the ON time is given by: (EQ6) 2 E = 0.5L ( I PK ) Joules (Region A in Figure 17) If the overall time period (TON + TOFF) is T, the power taken from the input is: 2 (EQ7) 0.5L ( I PK ) P IN = --------------------------- Watts T Assume output power is 0.8 PIN to establish an initial value of operating period T. T WAIT is determined by the time taken for the output voltage to fall to 0.99xV OUT. The longer the wait time, the lower will be the supply current of the converter. Longer wait times require increased output capacitance. Choose T WAIT = 10% T as a minimum starting point for maximum energy transfer. For very low power load applications, choose T WAIT 50% T. Output Loop Timing The output loop consists of the main inductor, P-channel synchronous switch (or diode if fitted), output capacitor and load. When the input loop is interrupted, the voltage on the LX pin rises (Lenz's Law). At the same time a comparator enables the synchronous switch, and energy stored in the inductor is transferred to the output capacitor and load. Inductor peak current supports the load and replenishes the charge lost from the output capacitor. The magnitude of the current from the inductor is monitored, and as it approaches zero, the synchronous switch is turned ON. No switching action continues until the output voltage falls below the output reference point (0.99 x VOUT ). Output power is composed of the DC component (Region C in Figure 17): (EQ8) T I PK OFF - ------------PREGION_C = V IN ------- 2 T Output power is also composed of the inductor component (Region B in Figure 17), neglecting efficiency loss: ams Datasheet [v1-11] 2015-Jan-28 Page 15 Document Feedback AS1310 - Detailed Description (EQ9) 0.5L ( I T ) 2 PK PREGION_B = --------------------------- Total power delivered to the load is the sum of EQ 8 and EQ 9: 2 (EQ10) I PK T OFF 0.5L ( I PK ) P TOTAL = V IN -------- ------------- + --------------------------2 T T From EQ 3 (using nominal values) peak current is given by: (EQ11) T ON V IN I PK = --------------------L Substituting EQ 11 into EQ 10 and re-arranging: 2 (EQ12) V IN T ON P TOTAL = ----------------------- ( 0.9T ) 2TL 0.9T incorporates a wait time T WAIT = 10% T Output power in terms of regulated output voltage and load resistance is: 2 (EQ13) V OUT P OUT = -----------------R LOAD Combining EQ 12 and EQ 13: 2 (EQ14) 2 V IN T ON V OUT ----------------- = ---------------------- ( 0.9T ) R LOAD 2TL Symbol reflects total energy loss between input and output and is approximately 0.8 for these calculations. Use EQ 14 to plot duty cycle (TON/T) changes for various output loadings and changes to VIN. Input Capacitor Selection The input capacitor supports the triangular current during the ON-time of the power switch, and maintains a broadly constant input voltage during this time. The capacitance value is obtained from choosing a ripple voltage during the ON-time of the power switch. Additionally, ripple voltage is generated by the equivalent series resistance (ESR) of the capacitor. For worst case, use maximum peak current values from the datasheet. (EQ15) I PEAK T ON C IN = -------------------------V RIPPLE Using TON = 1s, and I PEAK = 480mA, and V RIPPLE = 50mV, EQ 15 yields: CIN = 9.6F Nearest preferred would be 10F. (EQ16) Page 16 Document Feedback V PK _ RIPPLE _ ESR = I PK R ESR ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Detailed Description Typically, the ripple due to ESR is not dominant. ESR for the recommended capacitors (Murata GMR), ESR = 5m to 10m. For the AS1310, maximum peak current is 480mA. Ripple due to ESR is 2.4mV to 4.8mV. Ripple at the input propagates through the common supply connections, and if too high in value can cause problems elsewhere in the system. The input capacitance is an important component to get right. Output Capacitor Selection The output capacitor supports the triangular current during the OFF-time of the power switch (inductor discharge period), and also the load current during the wait time (Region D in Figure 17) and ON-time (Region A in Figure 17) of the power switch. (EQ17) COUT = I LOAD (TON + TWAIT ) (1 - 0.99)VOUT _ NOM Note(s): There is also a ripple component due to the equivalent series resistance (ESR) of the capacitor. Summary User Application Defines: V INmin, V INmax, VOUTmin, V OUTmax, I LOADmin, I LOADmax Inductor Selection: Select Max on-time = 0.5s to 3s for AS1310. Use EQ 3 to calculate inductor value. Use EQ 5 to determine OFF-time. Use EQ 6 to check that power delivery matches load requirements assume 70% conversion efficiency. Use EQ 13 to find overall timing period value of T at min V IN and max VOUT for maximum load conditions. Input Capacitor Selection: Choose a ripple value and use EQ 14 to find the value. Output Capacitor Selection: Determine T WAIT via EQ 6 or EQ 13, and use EQ 16 to find the value. ams Datasheet [v1-11] 2015-Jan-28 Page 17 Document Feedback AS1310 - Application Information Application Information The AS1310 is available with fixed output voltages from 1.8V to 3.3V in 50mV steps. Figure 18: AS1310 Block Diagram AS1310 VIN 0.7V to 3.6V LX Zero Crossing Detector L1 6.8F VOUT VOUT 1.8V to 3.3V COUT 22F LBI R3 + ON OFF EN VIN 100mV LBO + - CIN 22F - Startup Circuit ry Driver & Control Logic 0.6V 92.5% VREF + Imax Detection - REF VREF GND CREF 100nF AS1310 Features Shutdown. The part is in shutdown mode while the voltage at pin EN is below 0.1V and is active when the voltage is higher than 0.7V. Note(s): EN can be driven above V IN or V OUT, as long as it is limited to less than 3.6V. Output Disconnect and Inrush Limiting. During shutdown V OUT is going to 0V and no current from the input source is running through the device. This is true as long as the input voltage is higher than the output voltage. Feedthrough Mode. If the input voltage is higher than the output voltage the supply voltage is connected to the load through the device. To guarantee a proper function of the AS1310 it is not allowed that the supply exceeds the maximum allowed input voltage (3.6V). In this feedthrough mode the quiescent current is 35A (typ.). The device goes back into step-up mode when the oputput voltage is 4% (typ.) below V OUTNOM. Page 18 Document Feedback ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Application Information Power-OK and Low-Battery-Detect Functionality LBO goes low in startup mode as well as during normal operation if: * The voltage at the LBI pin is below LBI threshold (0.6V). This can be used to monitor the battery voltage. * LBI pin is connected to GND and V OUT is below 92.5% of its nominal value. LBO works as a power-OK signal in this case. The LBI pin can be connected to a resistive-divider to monitor a particular definable voltage and compare it with a 0.6V internal reference. If LBI is connected to GND an internal resistive-divider is activated and connected to the output. Therefore, the Power-OK functionality can be realized with no additional external components. The Power-OK feature is not active during shutdown and provides a power-ON-reset function that can operate down to V IN = 0.7V. A capacitor to GND may be added to generate a power-ON-reset delay. To obtain a logic-level output, connect a pull-up resistor R 3 from pin LBO to pin V OUT. Larger values for this resistor will help to minimize current consumption; a 100k resistor is perfect for most applications (see Figure 20). For the circuit shown in the left of Figure 19, the input bias current into LBI is very low, permitting large-value resistor-divider networks while maintaining accuracy. Place the resistor-divider network as close to the device as possible. Use a defined resistor for R 2 and then calculate R 1 as: (EQ18) V IN R 1 = R 2 ------------ - 1 V LBI Where: V LBI is 0.6V 30mV ams Datasheet [v1-11] 2015-Jan-28 Page 19 Document Feedback AS1310 - Application Information Figure 19: Typical Application with Adjustable Battery Monitoring VIN 0.7V to 3.6V L1 6.8H LX LBO Low Battery Detect AS1310 CIN 22F ON VIN OUT LBI REF EN GND VOUT 1.8V to 3.3V CREF 100nF COUT 22F OFF 0V Figure 20: Typical Application with LBO working as Power-OK VIN 0.7V to 3.6V L1 6.8H LX LBO Power OK Output AS1310 CIN 22F ON VIN OUT LBI REF EN GND VOUT 1.8V to 3.3V CREF 100nF COUT 22F OFF 0V Page 20 Document Feedback ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Application Information Thermal Shutdown To prevent the AS1310 from short-term misuse and overload conditions the chip includes a thermal overload protection. To block the normal operation mode all switches will be turned OFF. The device is in thermal shutdown when the junction temperature exceeds 150C. To resume the normal operation the temperature has to drop below 140C. A good thermal path has to be provided to dissipate the heat generated within the package. Otherwise it's not possible to operate the AS1310 at its usable maximal power. To dissipate as much heat as possible from the package into a copper plane with as much area as possible, it's recommended to use multiple vias in the printed circuit board. It's also recommended to solder the Exposed Pad (pin 9) to the GND plane. Note(s): Continuing operation in thermal overload conditions may damage the device and is considered bad practice. Always ON Operation In battery powered applications with long standby times as blood glucose meters, remote controls, soap dispensers, etc., a careful battery management is required. Normally a complex power management control makes sure that the DCDC is only switched ON, when it is really needed. With AS1310 this complex control can be saved completely, since the AS1310 is perfectly suited to support always-ON operations of the application. The efficiency at standby currents of e.g. 2As is around 45% (see Figure 21). Figure 21: Efficiency vs. Output Current for Always ON Operation; VOUT=3.3V 100 90 L1: XPL2010-682M Efficiency (%) 80 70 60 50 40 30 20 Vin = 1.1V 10 0 0.001 Vin = 1.5V 0.01 0.1 1 10 100 Output Current (mA) ams Datasheet [v1-11] 2015-Jan-28 Page 21 Document Feedback AS1310 - Application Information Component Selection Only four components are required to complete the design of the step-up converter. The low peak currents of the AS1310 allow the use of low value, low profile inductors and tiny external ceramic capacitors. Inductor Selection For best efficiency, choose an inductor with high frequency core material, such as ferrite, to reduce core losses. The inductor should have low DCR (DC resistance) to reduce the IR losses, and must be able to handle the peak inductor current without saturating. A 6.8H inductor with a >500mA current rating and <500m DCR is recommended. Figure 22: Recommended Inductors Part Number L DCR Current Rating Dimensions (L/W/T) XPL2010-682M 6.8H 421m 0.62A 2.0x1.9x1.0 mm EPL2014-682M 6.8H 287m 0.59A 2.0x2.0x1.4 mm LPS3015-682M 6.8H 300m 0.86A 3.0x3.0x1.5 mm LPS3314-682M 6.8H 240m 0.9A 3.3x3.3x1.3 mm LPS4018-682M 6.8H 150m 1.3A 3.9x3.9x1.7 mm XPL7030-682M 6.8H 59m 9.4A 7.0x7.0x3.0 mm LQH32CN6R8M53L 6.8H 250m 0.54A 3.2x2.5x1.55 mm LQH3NPN6R8NJ0L 6.8H 210m 0.7A 3.0x3.0x1.1 mm LQH44PN6R8MJ0L 6.8H 143m 0.72A 4.0x4.0x1.1 mm Page 22 Document Feedback Manufacturer Coilcraft www.coilcraft.com Murata www.murata.com ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Application Information Capacitor Selection The convertor requires three capacitors. Ceramic X5R or X7R types will minimize ESL and ESR while maintaining capacitance at rated voltage over temperature. The V IN capacitor should be 22F. The V OUT capacitor should be between 22F and 47F. A larger output capacitor should be used if lower peak to peak output voltage ripple is desired. A larger output capacitor will also improve load regulation on VOUT. See Figure 23 for a list of capacitors for input and output capacitor selection. Figure 23: Recommended Input and Output Capacitors Part Number C TC Code Rated Voltage Dimensions (L/W/T) GRM21BR60J226ME99 22F X5R 6.3V 0805, T=1.25mm GRM31CR61C226KE15 22F X5R 16V 1206, T=1.6mm GRM31CR60J475KA01 47F X5R 6.3V 1206, T=1.6mm Manufacturer Murata www.murata.com On the pin REF a 10nF capacitor with an Insulation resistance >1G is recommended. Figure 24: Recommended Capacitors for REF Part Number C TC Code Insulation Resistance Rated Voltage Dimensions (L/W/T) GRM188R71C104KA01 100nF X7R >5G 16V 0603, T=0.8mm GRM31CR61C226KE15 100nF X7R >5G 50V 0805, T=1.25mm Manufacturer Murata www.murata.com Layout Considerations Relatively high peak currents of 480mA (max) circulate during normal operation of the AS1310. Long printed circuit tracks can generate additional ripple and noise that mask correct operation and prove difficult to "de-bug" during production testing. Referring to Figure 2, the input loop formed by C1, V IN and GND pins should be minimized. Similarly, the output loop formed by C2, V OUT and GND should also be minimized. Ideally both loops should connect to GND in a "star" fashion. Finally, it is important to return C REF to the GND pin directly. ams Datasheet [v1-11] 2015-Jan-28 Page 23 Document Feedback AS1310 - Package Drawings & Mark ings Package Drawings & Markings The device is available in a TDFN (2x2) 8-pin package. Figure 25: Drawings and Dimensions XXX A2 Green RoHS Symbol Min Nom Max A A1 A3 L b D E e D2 E2 aaa bbb ccc ddd eee fff N 0.51 0.00 0.55 0.02 0.15 REF 0.325 0.25 2.00 BSC 2.00 BSC 0.50 BSC 1.60 0.90 0.15 0.10 0.10 0.05 0.08 0.10 8 0.60 0.05 0.225 0.18 1.45 0.75 - 0.425 0.30 1.70 1.00 - Note(s) and/or Footnote(s): 1. Dimensioning & tolerancing conform to ASME Y14.5M-1994. 2. All dimensions are in millimeters. Angles are in degrees. 3. Coplanarity applies to the exposed heat slug as well as the terminal. 4. Radius on terminal is optional. 5. N is the total number of terminals. Page 24 Document Feedback ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Ordering & Contact Information Ordering & Contact Information The device is available as the standard products shown in Figure 26. Figure 26: Ordering Information Delivery Form Package 1.8V Tape and Reel TDFN (2x2) 8-pin A8 2.0V Tape and Reel TDFN (2x2) 8-pin AS1310-BTDT-25 A9 2.5V Tape and Reel TDFN (2x2) 8-pin AS1310-BTDT-27 A7 2.7V Tape and Reel TDFN (2x2) 8-pin AS1310-BTDT-30 A6 3.0V Tape and Reel TDFN (2x2) 8-pin AS1310-BTDT-33(1) tbd 3.3V Tape and Reel TDFN (2x2) 8-pin AS1310-BTDT-xx(2) tbd tbd Tape and Reel TDFN (2x2) 8-pin Ordering Code Marking Output AS1310-BTDT-18 A2 AS1310-BTDT-20 Description Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter Note(s) and/or Footnote(s): 1. On request 2. Non-standard devices are available between 1.8V and 3.3V in 50mV steps. Buy our products or get free samples online at: www.ams.com/ICdirect Technical Support is available at: www.ams.com/Technical-Support Provide feedback about this document at: www.ams.com/Document-Feedback For further information and requests, e-mail us at: ams_sales@ams.com For sales offices, distributors and representatives, please visit: www.ams.com/contact Headquarters ams AG Tobelbaderstrasse 30 8141 Unterpremstaetten Austria, Europe Tel: +43 (0) 3136 500 0 Website: www.ams.com ams Datasheet [v1-11] 2015-Jan-28 Page 25 Document Feedback AS1310 - RoHS Compliant & ams Green Statement RoHS Compliant & ams Green Statement RoHS: The term RoHS compliant means that ams AG products fully comply with current RoHS directives. Our semiconductor products do not contain any chemicals for all 6 substance categories, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, RoHS compliant products are suitable for use in specified lead-free processes. ams Green (RoHS compliant and no Sb/Br): ams Green defines that in addition to RoHS compliance, our products are free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material). Important Information: The information provided in this statement represents ams AG knowledge and belief as of the date that it is provided. ams AG bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. ams AG has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. ams AG and ams AG suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. Page 26 Document Feedback ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Copyrights & Disclaimer Copyrights & Disclaimer Copyright ams AG, Tobelbader Strasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. Devices sold by ams AG are covered by the warranty and patent indemnification provisions appearing in its General Terms of Trade. ams AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein. ams AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with ams AG for current information. This product is intended for use in commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by ams AG for each application. This product is provided by ams AG "AS IS" and any express or implied warranties, including, but not limited to the implied warranties of merchantability and fitness for a particular purpose are disclaimed. ams AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of ams AG rendering of technical or other services. ams Datasheet [v1-11] 2015-Jan-28 Page 27 Document Feedback AS1310 - Document Status Document Status Document Status Product Preview Preliminary Datasheet Datasheet Datasheet (discontinued) Page 28 Document Feedback Product Status Definition Pre-Development Information in this datasheet is based on product ideas in the planning phase of development. All specifications are design goals without any warranty and are subject to change without notice Pre-Production Information in this datasheet is based on products in the design, validation or qualification phase of development. The performance and parameters shown in this document are preliminary without any warranty and are subject to change without notice Production Information in this datasheet is based on products in ramp-up to full production or full production which conform to specifications in accordance with the terms of ams AG standard warranty as given in the General Terms of Trade Discontinued Information in this datasheet is based on products which conform to specifications in accordance with the terms of ams AG standard warranty as given in the General Terms of Trade, but these products have been superseded and should not be used for new designs ams Datasheet [v1-11] 2015-Jan-28 AS1310 - Revision Information Revision Information Changes from 1-10 (2014-Nov-11) to current revision 1-11 (2015-Jan-28) Page Updated Figure 18 18 Updated Figures 19 & 20 20 Note(s) and/or Footnote(s): 1. Page and figure numbers for the previous version may differ from page and figure numbers in the current revision. 2. Correction of typographical errors is not explicitly mentioned. ams Datasheet [v1-11] 2015-Jan-28 Page 29 Document Feedback AS1310 - Content Guide Content Guide Page 30 Document Feedback 1 1 2 General Description Key Benefits & Features Applications 3 4 5 7 Pin Assignment Absolute Maximum Ratings Electrical Characteristics Typical Operating Characteristics 12 12 12 15 15 16 17 17 Detailed Description Hysteretic Boost Converter Input Loop Timing Inductor Choice Example Output Loop Timing Input Capacitor Selection Output Capacitor Selection Summary 18 18 19 21 21 22 22 23 23 Application Information AS1310 Features Power-OK and Low-Battery-Detect Functionality Thermal Shutdown Always ON Operation Component Selection Inductor Selection Capacitor Selection Layout Considerations 24 25 26 27 28 29 Package Drawings & Markings Ordering & Contact Information RoHS Compliant & ams Green Statement Copyrights & Disclaimer Document Status Revision Information ams Datasheet [v1-11] 2015-Jan-28 Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: ams: AS1310-BTDT-18 AS1310-BTDT-25 AS1310-BTDT-30 AS1310-25-EB AS1310-BTDT-33 AS1310-BTDT-27 AS1310-18-EB AS1310-30-EB AS1310-20-EB AS1310-33-EB