AS1310

Data sheet AS1310 U l t r a L o w Q u i e s c e n t C u r r e n t , H y s te r e t i c D C - D C S t e p - U p C o n v e r t e r 1 General Description The AS1310 is an ultra low IQ 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. See Ordering Information on page 14 for more information. 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 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. 2 Key Features Input Voltage Range: 0.7V to 3.6V Fixed Output Voltage Range: 1.8V to 3.3V Output Current: 60mA @ VIN=0.9V, VOUT=1.8V Quiescent Current: 1µA (typ.) Shutdown Current: < 100nA Up to 92% efficiency Output Disconnect in Shutdown Feedthrough Mode when VIN > VOUT Adjustable Low Battery detection No external diode or transistor required Over Temperature Protection TDFN (2x2) 8-pin package 3 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 1. AS1310 - Typical Application Diagram L1 6.8µH VIN 0.7V to 3.6V C1 22µF R1 R2 On Off 3 LX 8 VIN 1 LBI 7 EN 2 GND 6 LBO Low Battery Detect R3 C2 22µF CREF 100nF VOUT 1.8V to 3.3V AS1310 4 VOUT 5 REF www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 1 - 15 AS1310 Datasheet - P i n A s s i g n m e n t s 4 Pin Assignments Figure 2. Pin Assignments (Top View) LBI 1 GND 2 LX 3 VOUT 4 8 VIN AS1310 9 7 EN 6 LBO 5 REF Pin Descriptions Table 1. Pin Descriptions Pin Number 1 2 3 4 5 6 7 8 9 Pin Name LBI GND LX VOUT REF LBO EN VIN NC Description Low Battery Comparator Input. 0.6V Threshold. May not be left floating. If connected to GND, LBO is working as Power Output OK. Ground External Inductor Connector. Output Voltage. Decouple VOUT with a 22µF ceramic capacitor as close as possible to VOUT and GND. Reference Pin. Connect a 100nF ceramic capacitor to this pin. Low Battery Comparator Output. Open-drain output. Enable Pin. Logic controlled shutdown input. 1 = Normal operation; 0 = Shutdown; shutdown current 1.75V 2. LBO goes low in startup mode as well as during normal operation if: 1) The voltage at the LBI pin is below LBI threshold. 2) The voltage at the LBI pin is below 0.1V and VOUT is below 92.5% of its nominal value. Note: All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality Control) methods. www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 5 - 15 AS1310 Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s 7 Typical Operating Characteristics TAMB = +25°C, unless otherwise specified. Figure 3. Efficiency vs. Output Current; VOUT = 1.8V 90 85 80 Figure 4. Efficiency vs. Output Current; VOUT = 1.8V 90 85 80 L1: XPL2010-682M L1: XPL7030-682M Efficiency (%) 70 65 60 55 50 45 40 0.01 0.1 1 10 Vin = 0.9V Vin = 1.2V Vin = 1.5V Efficiency (%) 75 75 70 65 60 55 50 45 40 0.01 0.1 1 10 Vin = 0.9V Vin = 1.2V Vin = 1.5V 100 1000 100 1000 Output Current (mA) Figure 5. Efficiency vs. Output Current; VOUT = 3.0V 100 95 90 85 80 75 70 65 60 55 50 45 40 0.01 0.1 1 10 Vin = 0.9V Vin = 1.2V Vin = 1.5V Vin = 1.8V Vin = 2.4V Output Current (mA) Figure 6. Efficiency vs. Output Current; VOUT = 3.0V 100 95 90 85 80 75 70 65 60 55 50 45 40 0.01 0.1 1 10 Vin = 0.9V Vin = 1.2V Vin = 1.5V Vin = 1.8V Vin = 2.4V L1: XPL2010-682M L1: XPL7030-682M Efficiency (%) 100 1000 Efficiency (%) 100 1000 Output Current (mA) Figure 7. Efficiency vs. Input Voltage; VOUT = 1.8V 100 95 90 Output Current (mA) Figure 8. Maximum Output Current vs. Input Voltage 180 160 L1: XPL2010-682M Output Current (mA) . Iout = 1mA Iout=10mA Iout=50mA 140 120 100 80 60 40 Vout = 1.8V Efficiency (%) 85 80 75 70 65 60 55 50 0.7 0.9 1.1 1.3 1.5 1.7 1.9 20 0 0 0.5 1 1.5 2 Vout = 3.0V 2.5 3 Input Voltage (V) www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 Input Voltage (V) 6 - 15 AS1310 Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s Figure 9. Start-up Voltage vs. Output Current 1 0.95 Figure 10. RON vs. Temperature 1 0.9 0.8 0.7 Start-up Voltage (V) 0.9 0.85 0.75 0.7 0.65 0.6 0.55 0.5 0 1 2 3 4 5 6 7 8 9 10 R ON (Ω) 0.8 0.6 0.5 0.4 0.3 0.2 0.1 0 -40 -15 10 35 60 PM OS NM OS 85 Output Current (mA) Temperature (°C) Figure 11. Output Voltage Ripple; VIN = 2V, VOUT = 3V, Rload = 100Ω VOUT (AC) 5µs/Div www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 100mV/Div 200mA/Div ILX 2V/Div VLX Revision 1.04 7 - 15 AS1310 Datasheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description The AS1310 is available with fixed output voltages from 1.8V to 3.3V in 50mV steps. Figure 12. AS1310 - Block Diagram 0.7 to 3.6V Input CIN 22µF 6.8µH LX Zero Crossing Detector Startup Circuitry 1.8V to 3.3V Output VOUT COUT 22µF VIN Driver and Control Logic R3 – + LBO LBI Imax Detection EN AS1310 VREF REF CREF 100nF GND 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: EN can be driven above VIN or VOUT, as long as it is limited to less than 3.6V. Output Disconnect and Inrush Limiting During shutdown VOUT 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 feedtrough mode the quiescent current is 35µA (typ.). The device goes back into step-up mode when the oputput voltage is 4% (typ.) below VOUTNOM. www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 8 - 15 AS1310 Datasheet - D e t a i l e d D e s c r i p t i o n 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 VOUT 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 realised 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 VIN = 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 R3 from pin LBO to pin VOUT. Larger values for this resistor will help to minimize current consumption; a 100kΩ resistor is perfect for most applications (see Figure 14 on page 10). For the circuit shown in the left of Figure 13, 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 R2 and then calculate R1 as: V IN R 1 = R 2 ⋅ ⎛ ---------- – 1⎞ ⎝ V LBI ⎠ Where: VLBI is 0.6V. (EQ 1) Figure 13. Typical Application with adjustable Battery Monitoring L1 6.8µH VIN 0.7V to 3.6V C1 22µF R1 R2 On Off 3 LX 8 VIN 1 LBI 7 EN 2 GND 6 LBO Low Battery Detect R3 C2 22µF CREF 100nF VOUT 1.8V to 3.3V AS1310 4 VOUT 5 REF www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 9 - 15 AS1310 Datasheet - D e t a i l e d D e s c r i p t i o n Figure 14. Typical Application with LBO working as Power-OK L1 6.8µH VIN 0.7V to 3.6V C1 22µF 3 LX 8 VIN 1 LBI On Off 7 EN 2 GND 6 LBO Low Battery Detect R3 C2 22µF CREF 100nF VOUT 1.8V to 3.3V AS1310 4 VOUT 5 REF 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 150°C. To resume the normal operation the temperature has to drop below 140°C. 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 useable 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: Continuing operation in thermal overload conditions may damage the device and is considered bad practice. www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 10 - 15 AS1310 Datasheet - A p p l i c a t i o n I n f o r m a t i o n 9 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 I²R losses, and must be able to handle the peak inductor current without saturating. A 6.8µH inductor with a >500mA current rating and 1GΩ is recommended. Table 6. Recommended Capacitors for REF Part Number GRM188R71C104KA01 GRM31CR61C226KE15 C 100nF 100nF TC Code X7R X7R Insulation Resistance >5GΩ >5GΩ Rated Voltage 16V 50V Dimensions (L/W/T) 0603, T=0.8mm 0805, T=1.25mm Manufacturer Murata www.murata.com www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 11 - 15 AS1310 Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s 10 Package Drawings and Markings Figure 15. TDFN (2x2) 8-pin Marking Package Code: XXX - encoded Datecode www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 12 - 15 AS1310 Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s Figure 16. TDFN (2x2) 8-pin package Diagram www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 13 - 15 AS1310 Datasheet - O r d e r i n g I n f o r m a t i o n 11 Ordering Information The device is available as the standard products shown in Table 7. Table 7. Ordering Information Ordering Code AS1310-BTDT-18 AS1310-BTDT-20 AS1310-BTDT-25 AS1310-BTDT-27 AS1310-BTDT-30 AS1310-BTDT-33 AS1310-BTDT-xx 1 Marking A2 A8 A9 A7 A6 tbd tbd Output 1.8V 2.0V 2.5V 2.7V 3.0V 3.3V tbd Description Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter Delivery Form Tape and Reel Tape and Reel Tape and Reel Tape and Reel Tape and Reel Tape and Reel Tape and Reel Package TDFN (2x2) 8-pin TDFN (2x2) 8-pin TDFN (2x2) 8-pin TDFN (2x2) 8-pin TDFN (2x2) 8-pin TDFN (2x2) 8-pin TDFN (2x2) 8-pin 2 1. On request 2. Non-standard devices are available between 1.8V and 3.3V in 50mV steps. Note: All products are RoHS compliant and austriamicrosystems green. Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect Technical Support is found at http://www.austriamicrosystems.com/Technical-Support For further information and requests, please contact us mailto:sales@austriamicrosystems.com or find your local distributor at http://www.austriamicrosystems.com/distributor www.austriamicrosystems.com/DC-DC_Step-Up/AS1310 Revision 1.04 14 - 15 AS1310 Datasheet Copyrights Copyright © 1997-2011, austriamicrosystems AG, Tobelbaderstrasse 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. 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