Datasheet AS1321 130mA Step-Up DC-DC Converter 1 General Description 2 Key Features ! Fixed Output Voltage: +5.0V ! Output Current: Up to 130mA @ 2V VBATT ! Internal Synchronous Rectifier ! Shutdown Mode Supply Current: Less Than 1A In order to save power the AS1321 features a shutdown mode, where it draws less than 1A. In shutdown mode the battery is connected directly to the output enabling the supply of real-timeclocks. ! Efficiency: Up to 96% ! Minimum Input Voltage: +1.5V ! Accurate Shutdown Low-Battery Cutoff Threshold The AS1321 provides a power-on reset output that goes highimpedance when the output reaches 90% of its regulation point. ! Battery Input Connected to Pin OUT in Shutdown Mode for Backup Power The SHDNN trip threshold of the AS1321 can be used as an input voltage detector that disables the device when the battery voltage falls to a predetermined level. ! 6-pin SOT23 Package The AS1321 is a high-efficiency step-up DC-DC converter designed to generate a fixed output voltage of +5.0V. The AS1321 achieves an efficiency of up to 96%. The minimum input voltage is +1.5V, the output voltage is fixed at +5.0V, and output current is up to 130mA @ 2V VBATT. An internal synchronous rectifier is included, which is parallel with the external Schottky diode. The AS1321 is available in a 6-pin SOT23 package. 3 Applications The AS1321 is ideal for low-power applications where ultra-small size is critical as in medical diagnostic equipment, hand-held instruments, pagers, digital cameras, remote wireless transmitters, cordless phones, and PC cards. The device is also perfect as a local +5.0V supply or as a battery backup. Figure 1. AS1321 - Typical Application Diagram 2 4 +1.5V to +5.0V Battery L1 10H CIN 22F On Off LX OUT AS1321 1 6 RESETN COUT 22F R1 100k RESETN Output 3 GND SHDNN www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 +5.0V Output 5 BATT Revision 1.03 1 - 13 AS1321 Datasheet - P i n A s s i g n m e n t s 4 Pin Assignments Figure 2. Pin Assignments (Top View) SHDNN 1 BATT 2 GND 3 AS1321 6 RESETN 5 OUT 4 LX 4.1 Pin Descriptions Table 1. Pin Descriptions Pin Number Pin Name Description 1 SHDNN 2 BATT Battery Voltage Input 3 GND Ground 4 LX 5 OUT 6 RESETN Active-Low Logic Shutdown Input 0 = The AS1321 is off and the current into BATT is 1A (typ). 1 = The AS1321 is on. External Inductor Connection Output Voltage Active-Low reset output www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 Revision 1.03 2 - 13 AS1321 Datasheet - A b s o l u t e M a x i m u m R a t i n g s 5 Absolute Maximum Ratings Stresses beyond those listed in Table 2 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 Section 6 Electrical Characteristics on page 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 2. Absolute Maximum Ratings Parameter Min Max Units All Pins to GND -0.3 7 V 1 A 100 mA JEDEC 78 500 mW (JA = 9.1mW/C above +70C) LX Current Latch-Up -100 Package Power Dissipation (TAMB = +70C) Operating Temperature Range -40 +85 C Electrostatic Discharge -500 +500 V Humidity (Non-Condensing) 5 85 % Storage Temperature Range -55 125 C Junction Temperature 150 C Package Body Temperature 260 C www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 Revision 1.03 Comments HBM MIL-Std. 883E 3015.7 methods The reflow peak soldering temperature (body temperature) specified is in compliance with IPC/JEDEC J-STD-020 "Moisture/ Reflow Sensitivity Classification for Non-Hermetic Solid State Surface Mount Devices". 3 - 13 AS1321 Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s 6 Electrical Characteristics TAMB = -40 to +85C, VBATT = +2V, VOUT = +5.0, VSHDNN = +1.5V (unless otherwise specified). Typical values @ TAMB = +25C. Table 3. Electrical Characteristics Symbol Parameter VBATT Battery Input Range Conditions VSU Startup Battery Input Voltage VOUT Output Voltage RNCH N-Channel On-Resistance RPCH P-Channel On-Resistance IMAX N-Channel Switch Current Limit tON Switch Maximum On-Time Synchronous Rectifier Zero-Crossing Current TAMB = +25C 8 TAMB = -40 to +85C 0 Typ 1.5 1 2 RLOAD = 100, TAMB = +25C 1.22 RLOAD = 100, TAMB = -40 to +85C 1.24 TAMB = +25C 4.950 TAMB = -40 to +85C 4.875 ILX = 100mA, TAMB = +25C 5.000 0.3 ILX = 100mA, TAMB = +25C 3 0.4 Quiescent Current into BATT 3 Shutdown Current into BATT 1 SHDNN Threshold TAMB = +25C 550 TAMB = -40 to +85C 450 TAMB = +25C 5 TAMB = -40 to +85C 4 VOUT = +5.5V, TAMB = +25C 700 RESETN Voltage Low RESETN Leakage Current LX Leakage Current 1.5 5.050 1.2 1.3 850 950 7 9 10 30 60 65 35 55 60 VSHDNN = 0V, TAMB = +25C 0.01 VSHDNN = 0V, TAMB = -40 to +85C 1 2 VOUT = +5.5V, TAMB = +25C 0.01 VOUT = +5.5V, TAMB = -40 to +85C 1 2 VSHDNN = 0V, TAMB = +25C 0.01 1 VSHDNN = 0V, TAMB = -40 to +85C 2 VBATT = +1.5 to +5.0V 0.3 Rising Edge, TAMB = +25C 1.185 Rising Edge, TAMB = -40 to +85C 1.170 SHDNN Threshold Hysteresis RESETN Threshold V 1.6 VOUT = +5.5V, TAMB = -40 to +85C Shutdown Current into OUT Unit 5.0 1.5 ILX = 100mA, TAMB = -40 to +85C 1 Max 5.125 ILX = 100mA, TAMB = -40 to +85C Quiescent Current into OUT SHDNN Logic Low Min 1.228 1.271 1.286 0.02 Falling Edge, TAMB = +25C 4.288 Falling Edge, TAMB = -40 to +85C 4.242 4.500 V V mA s mA A A A A V V V 4.712 4.758 IRESETN = 1mA, VOUT = +2.5V, TAMB = +25C 0.15 IRESETN = 1mA, VOUT = +2.5V, TAMB = -40 to +85C 0.2 V V VRESETN = +5.5V, TAMB = +25C 0.1 VRESETN = +5.5V, TAMB = +85C 1 TAMB = +25C 0.1 TAMB = +85C 10 100 1000 nA nA ILOAD Maximum Load Current VBATT = +2V 130 mA Efficiency VBATT = +3V, ILOAD = 100mA 91 % 1. Guaranteed by design. 2. Voltage which triggers next loading cycle. Ripple and rms value depend on external components. 3. The Quiescent current is measured while the DC-DC Converter is not switching. 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/AS1321 Revision 1.03 4 - 13 AS1321 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 VBATT = 2.0V, VOUT = 5.0V, TAMB = +25C (unless otherwise specified). Figure 3. Efficiency vs. Load Current Figure 4. Efficiency vs. Input Voltage 100 100 95 90 VBATT = 4.5V Efficiency (%) Efficiency (%) VBATT = 3.5V VBATT = 3V 90 VBATT = 2.5V VBATT = 2V 85 80 70 VBATT = 1.5V 80 Iout = 1mA 60 Iout = 10mA Iout = 100mA 75 50 1 10 100 1000 1 2 Load Current (mA) 4 5 Figure 6. VOUT vs. VBATT; On, 470 6 6 5 5 Output Voltage (V) Output Voltage (V) Figure 5. VOUT vs. VBATT; On, 39 4 3 2 1 4 3 2 1 0 0 0 1 2 3 4 5 0 1 Battery Voltage (V) 2 3 4 5 4 5 Battery Voltage (V) Figure 7. VOUT vs. VBATT; Shutdown, 130mA Load Figure 8. VOUT vs. VBATT; Shutdown, no Load 6 6 5 5 Output Voltage (V) Output Voltage (V) 3 Battery Voltage (V) 4 3 2 1 4 3 2 1 0 0 1.5 2 2.5 3 3.5 4 4.5 5 0 Battery Voltage (V) www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 1 2 3 Battery Voltage (V) Revision 1.03 5 - 13 AS1321 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. Maximum Output Current vs. VBATT Figure 10. Startup Voltage vs. Load Resistance 5 350 4 300 Supply Voltage (V) Maximum Output Current (mA) 400 250 200 150 100 3 2 1 50 0 0 1.5 2 2.5 3 3.5 4 4.5 5 10 Battery Voltage (V) 100 1000 10000 Load Resistance (Ohm) Figure 12. Waveforms; RLOAD = 100, VBATT = 3V Figure 11. Input Current vs. Input Voltage 400 VOUT 300 2V/Div 250 VLX Input Current (A) Iout = 34A 50mV/Div Iout = 4A 350 200 150 IL 500mA/Div 100 50 0 1 2 3 4 5 10s/Div Battery Voltage (V) VOUT 2mA IOUT 1V/Div VOUT VIN 130mA 100s/Div www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 100mV/Div Figure 14. Load Transient 100mV/Div Figure 13. Line Transient 500s/Div Revision 1.03 6 - 13 AS1321 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 www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 1V/Div VOUT VSHDNN 2ms/Div 2V/Div 1V/Div Figure 16. Shutdown Response; RLOAD = 100 1V/Div VIN VOUT Figure 15. On / Off Response; RLOAD = 100 500s/Div Revision 1.03 7 - 13 AS1321 Datasheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description The AS1321 is a high-efficiency, compact step-up converter with 35A quiescent supply current which ensures the highest efficiency over a wide load range. With a minimum of +1.5V input voltage, the device is well suited for applications with one- or two-cells, such as lithium ion (Li+), nickel-metal-hydride (NiMH), or alkaline. Figure 17. AS1321 - Block Diagram +1.5 to +5.0V Battery CIN 22F Zero Crossing Detector 4 10H LX BATT OUT COUT 22F Startup Circuitry Driver and Control Logic 2 5 - + +1.228V VREF Current Limiter - 1 AS1321 SHDNN +5.0V Output +1.1V + 6 RESETN GND 3 The input battery is connected to the device through an inductor and an internal P-FET when pin SHDNN is low. In this state, the step-up converter is off and the voltage drop across the P-FET body diode is eliminated, and the input battery can be used as a battery-backup or realtime-clock supply. The built-in synchronous rectifier significantly improves efficiency. 8.1 Control Circuitry The AS1321 integrated current-limited key circuitry provides low quiescent current and extremely-high efficiency over a wide VOUT range without the need for an oscillator. Inductor current is limited by the 7s switch maximum on-time or by the 0.7A N-channel current limit. At each cycle, the inductor current must ramp down to zero after the on-time before the next cycle may start. When the error comparator senses that the output has fallen below the regulation threshold, another cycle begins. www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 Revision 1.03 8 - 13 AS1321 Datasheet - D e t a i l e d D e s c r i p t i o n 8.2 Shutdown When pin SHDNN is low the AS1321 is switched off and no current is drawn from battery; when pin SHDNN is high the device is switched on. If SHDNN is driven from a logic-level output, the logic high-level (on) should be referenced to VOUT to avoid intermittently switching the device on. Note: If pin SHDNN is not used, it should be connected directly to pin OUT. In shutdown the battery input is connected to the output through the inductor and the internal synchronous rectifier P-FET. This allows the input battery to provide backup power for devices such as an idle microcontroller, memory, or real-time-clock, without the usual diode forward drop. In this way a separate backup battery is not needed. In cases where there is residual voltage during shutdown, some small amount of energy will be transferred from pin OUT to pin BATT immediately after shutdown, resulting in a momentary spike of the voltage at pin BATT. The ratio of CIN and COUT partly determine the size and duration of this spike, as does the current-sink ability of the input device. 8.3 Low-Battery Cutoff The AS1321 SHDNN trip threshold (1.228V) can be used as an input voltage detector that disables the device when the battery input voltage falls to a pre-set level. An external resistor-divider network can be used to set the battery-detection voltage (see Figure 18). Figure 18. Low-Battery Cutoff Application Diagram 2 +1.5 to +5.0V Battery 5 BATT CIN 22F 4 R1 220k L1 10H LX OUT AS1321 1 R2 1M 10nF R3 100k 6 RESETN COUT 22F +5.0V Output Power-On Reset 3 GND SHDNN For the resistor-divider network shown in Figure 18, calculate the value for R1 by: R1 = R2 x ((VOFF/VSHDNN) - 1) (EQ 1) Where: VOFF is the battery voltage at which the AS1321 shuts down. VSHDNN = 1.228V The value of R2 should be between 100k and 1M to minimize battery drain. Note: Input ripple can cause false shutdowns, therefore to minimize the effect of ripple, a low-value capacitor from SHDNN to GND should be used to filter out input noise. The value of the capacitor should be such that the R/C time constant is > 2ms. 8.4 Power-On Reset The AS1321 provides a power-on reset output (RESETN) that goes high-impedance when the output reaches 90% of its regulation point. RESETN goes low when the output is below 90% of the regulation point. A 100k to 1M pullup resistor between pin RESETN and pin OUT can provide a microprocessor logic control signal. Note: Connect pin RESETN to GND when the power-on reset feature is not used. www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 Revision 1.03 9 - 13 AS1321 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 9.1 Inductor Selection The control circuitry of the AS1321 permits a wide range of inductor values to be selected - from 4.7 to 47H; 10H is ideal for most applications. The intended application should dictate the value of L. The trade-off between required PCB surface area and desired output ripple are the determining factors: smaller values for L require less PCB space, larger values of L reduce output ripple. If the value of L is large enough to prevent IMAX from being reached before tON expires, the AS1321 output power will be reduced. For maximum output current calculate the value for L as: (VBATT(MAX) (1s))/0.7A < L < (VBATT(MIN)(7s))/0.7A (EQ 2) IOUT(MAX) = (0.7A/2)(VBATT(MIN) - (0.7A/2)(RNCH + RIND))/VOUT (EQ 3) Where: RIND is the inductor series resistance. RNCH is the RDS(ON) of the N-channel MOSFET (0.3 typ). Note: Coils should be able to handle 500mARMS and have a ISAT 1A and should have a RIND 100m. 9.2 Capacitor Selection 9.2.1 COUT Selection Choose a COUT value to achieve the desired output ripple percentage. A 22F ceramic capacitor is a good initial value. The value for COUT can be determined by: 2 COUT > (L + 2.5H) x VBATT(MAX) / (r% x 4) (EQ 4) Where: r is the desired output ripple in %. 9.2.2 CIN Selection CIN reduces the peak current drawn from the battery and can be the same value as COUT. A larger value for CIN can be used to further reduce ripple and improve AS1321 efficiency. 9.3 External Diode An external Schottky diode must be connected, in parallel with the on-chip synchronous rectifier, from LX to OUT. Use diodes such as MBR0520L, EP05Q03L, or the generic 1N5817. The diode should be rated for 500mA, since it carries current during startup and after the synchronous rectifier turns off. The Schottky diode must be connected as close to the IC as possible. Ordinary rectifier diodes must not be used, since the slow recovery rate will compromise efficiency. 9.4 PC Board Layout and Grounding Well-designed printed circuit-board layout is important for minimizing ground bounce and noise. ! Place pin GND lead and the ground leads of CIN and COUT as close to the device as possible. ! Keep the lead to pin LX as short as possible. ! To maximize output power and efficiency and minimize output ripple voltage, use a ground plane and solder the GND pin directly to the ground plane. www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 Revision 1.03 10 - 13 AS1321 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 The AS1321 is available in a 6-pin SOT23 package. Figure 19. 6-pin SOT23 Package Notes: 1. All dimensions are in millimeters. 2. Foot length is measured at the intercept point between datum A and lead surface. 3. Package outline exclusive of mold flash and metal burr. 4. Pin 1 is the lower left pin when reading the top mark from left to right. 5. Pin 1 identifier dot is 0.3mm. min and is located above pin 1. 6. Meets JEDEC MO178. www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 Revision 1.03 Symbol A A1 A2 b C D E E1 L e Min 0.90 0.00 0.90 0.35 0.08 2.80 2.60 1.50 0.35 Max 1.45 0.15 1.30 0.50 0.20 3.00 3.00 1.75 0.55 0.95 REF 0 10 11 - 13 AS1321 Datasheet - O r d e r i n g I n f o r m a t i o n 11 Ordering Information The AS1321 is available as the standard products shown in Table 4. Table 4. Ordering Information Ordering Code Marking Description Delivery Form Package AS1321-T ASKX 130mA Step-Up DC-DC Converter Tape and Reel 6-pin SOT23 Note: All products are RoHS compliant. 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 Design the AS1321 online at http://www.austriamicrosystems.com/analogbench analogbench is a powerful design and simulation support tool that operates in on-line and off-line mode to evaluate performance and generate application-specific bill-of-materials for austriamicrosystems' power management devices. www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 Revision 1.03 12 - 13 AS1321 Datasheet Copyrights Copyright (c) 1997-2010, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered (R). 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. All products and companies mentioned are trademarks or registered trademarks of their respective companies. Disclaimer Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems 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 austriamicrosystems AG for current information. This product is intended for use in normal 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 austriamicrosystems AG for each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location. The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems 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 austriamicrosystems AG rendering of technical or other services. Contact Information Headquarters austriamicrosystems AG Tobelbaderstrasse 30 A-8141 Unterpremstaetten, Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com/contact www.austriamicrosystems.com/DC-DC_Step-Up/AS1321 Revision 1.03 13 - 13