AS1320

AS1320 2 0 0 m A St e p - U p D C - D C C o n v e r t e r D a ta S he e t 1 General Description The AS1320 is a high-efficiency step-up DC-DC converter designed to generate a fixed voltage of +3.3V. The AS1320 achieves an efficiency of up to 90%. The minimum input voltage is 1.5V, the output voltage is fixed at 3.3V, and output current is up to 200mA (@ 2V). In order to save power the AS1320 features a shutdown mode, where it draws less than 1µA. In shutdown mode the battery is connected directly to the output enabling the supply of real-time-clocks. The AS1320 provides a power-on reset output that goes high-impedance when the output reaches 90% of its regulation point. The SHDNN trip threshold of the AS1320 can be used as an input voltage detector that disables the device when the battery voltage falls to a predetermined level. An internal synchronous rectifier is included, thus an external transistor or Schottky diode is not required. The AS1320 is available in a 6-pin SOT23 package. 2 Key Features ! ! ! ! ! ! ! ! ! Fixed Output Voltage: 3.3V Output Current: Up to 200mA (@ 2V) Internal Synchronous Rectifier Requires No External Schottky Diode or FETs Shutdown Mode Supply Current: Less Than 1µA Efficiency: Up to 90% Minimum Input Voltage: +1.5V Accurate Shutdown Low-Battery Cutoff Threshold Battery Input Connected to Pin OUT in Shutdown Mode for Backup Power 6-pin SOT23 Package ! 3 Applications The AS1320 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 3.3V supply or as a battery backup. Figure 1. Application Diagram 2 BATT 5 OUT COUT 22µF +3.3V Output R1 100kΩ RESETN Output +1.5 to +3.5V Battery CIN 22µF 4 L1 10µH LX AS1320 6 RESETN On Off 1 SHDNN 3 GND www.austriamicrosystems.com Revision 1.03 1 - 12 AS1320 Data Sheet - P i n o u t 4 Pinout Pin Assignments Figure 2. Pin Assignments (Top View) SHDNN 1 6 RESETN BATT 2 AS1320 5 OUT GND 3 4 LX Pin Descriptions Table 1. Pin Descriptions Name SHDNN BATT GND LX OUT RESETN Pin Number 1 2 3 4 5 6 Description Active-Low Logic Shutdown Input 0 = The AS1320 is off and the current into BATT is ≤ 1µA (typ). 1 = The AS1320 is on. Battery Voltage Input Ground External Inductor Connection Output Voltage Active-Low reset output www.austriamicrosystems.com Revision 1.03 2 - 12 AS1320 Data Sheet - 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 All Pins to GND LX Current Latch-Up Package Power Dissipation (TAMB = +70ºC) Operating Temperature Range Electrostatic Discharge Humidity (Non-Condensing) Storage Temperature Range Junction Temperature -40 -500 5 -55 -100 Min -0.3 Max 7 1 100 500 +85 +500 85 125 150 Units V A mA mW ºC V % ºC ºC The reflow peak soldering temperature (body temperature) specified is in compliance with IPC/JEDEC J-STD-020C “Moisture/ Reflow Sensitivity Classification for Non-Hermetic Solid State Surface Mount Devices”. HBM MIL-Std. 883E 3015.7 methods JEDEC 78 (ΘJA = 9.1mW/ºC above +70ºC) Comments Package Body Temperature 260 ºC www.austriamicrosystems.com Revision 1.03 3 - 12 AS1320 Data Sheet - 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 +85ºC, VBATT = +2V, VOUT = +3.3, VSHDNN = +1.5V (unless otherwise specified). Typ values @ TAMB = +25ºC. Table 3. Electrical Characteristics Parameter Battery Input Range Startup Battery Input Voltage Output Voltage 2 1 Symbol VBATT VSU VOUT RNCH RPCH 1 Conditions RLOAD = 47Ω, TAMB = +25ºC RLOAD = 47Ω, TAMB = -40 to +85ºC TAMB = +25ºC TAMB = -40 to +85ºC ILX = 100mA, TAMB = +25ºC ILX = 100mA, TAMB = -40 to +85ºC ILX = 100mA, TAMB = +25ºC ILX = 100mA, TAMB = -40 to +85ºC TAMB = +25ºC TAMB = -40 to +85ºC TAMB = +25ºC TAMB = -40 to +85ºC TAMB = +25ºC TAMB = -40 to +85ºC VOUT = +3.5V, TAMB = +25ºC VOUT = +3.5V, TAMB = -40 to +85ºC VSHDNN = 0V, TAMB = +25ºC VSHDNN = 0V, TAMB = -40 to +85ºC VOUT = +3.5V, TAMB = +25ºC VOUT = +3.5V, TAMB = -40 to +85ºC VSHDNN = 0V, TAMB = +25ºC VSHDNN = 0V, TAMB = -40 to +85ºC VBATT = +1.5 to +3.5V Rising Edge, TAMB = +25ºC Rising Edge, TAMB = -40 to +85ºC Falling Edge, TAMB = +25ºC Falling Edge, TAMB = -40 to +85ºC IRESETN = 1mA, VOUT = +2.5V, TAMB = +25ºC IRESETN = 1mA, VOUT = +2.5V, TAMB = -40 to +85ºC VRESETN = +5.5V, TAMB = +25ºC VRESETN = +5.5V, TAMB = +85ºC TAMB = +25ºC TAMB = +85ºC Min 1.5 Typ 1.22 1.24 Max 3.5 1.5 3.333 3.373 1.2 1.5 1.3 1.6 850 950 9 10 60 65 55 60 1 2 1 2 1 2 0.3 Unit V V V Ω Ω mA µs mA µA µA µA µA V V V 3.267 3.217 3.300 0.3 0.4 N-Channel On-Resistance P-Channel On-Resistance N-Channel Switch Current Limit Switch Maximum On-Time Synchronous Rectifier Zero-Crossing Current Quiescent Current into OUT Shutdown Current into OUT Quiescent Current into BATT Shutdown Current into BATT SHDNN Logic Low 1 IMAX tON 550 450 5 4 8 0 700 7 30 35 0.01 0.01 0.01 SHDNN Threshold SHDNN Threshold Hysteresis RESETN Threshold 1.185 1.170 1.228 0.02 1.271 1.286 2.830 2.800 3.000 3.110 3.140 0.15 V RESETN Voltage Low V 0.2 0.1 1 0.1 10 200 90 1000 100 nA nA mA % RESETN Leakage Current LX Leakage Current Maximum Load Current Efficiency ILOAD η VBATT = +2V VBATT = +3V, ILOAD = 100mA 1. Guaranteed by design. 2. Voltage which triggers next loading cycle. Ripple and rms value depend on external components. www.austriamicrosystems.com Revision 1.03 4 - 12 AS1320 Data Sheet - 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 VOUT = 3.3V, VBATT = +2V, TAMB = +25ºC. Figure 3. VOUT vs. VBATT; On, 16Ω 4 Figure 4. VOUT vs. VBATT; On, 330Ω 4 Output Voltage (V)a Output Voltage (V)a 3 3 2 2 1 1 0 0 1 2 3 4 0 0 1 2 3 4 Battery Voltage (V) Figure 5. VOUT vs. VBATT; Shutdown, 200mA Load 6 5 Battery Voltage (V) Figure 6. VOUT vs. VBATT; Shutdown, No Load 6 5 Output Voltage (V)a 4 3 2 1 0 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 Output Voltage (V)a 4 3 2 1 0 0 2 4 6 Battery Voltage (V) Figure 7. Maximum Output Current vs. VBATT 600 Battery Voltage (V) Figure 8. Startup Voltage vs. Load Resistance 3 2.5 Maximum Output Current (mA)a 500 Startup Voltage (V)a 400 300 200 100 0 1.5 2 2.5 3 3.5 2 1.5 1 0.5 0 10 100 1000 10000 Battery Voltage (V) Load Resistance (Ω ) www.austriamicrosystems.com Revision 1.03 5 - 12 AS1320 Data Sheet - 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. Line Transient Figure 10. Load Transient VOUT (AC Coupled) 100mV/Div VOUT (AC Coupled) 1V/Div 200mA IOUT VIN 2mA 100µs/Div 100µs/Div Figure 11. On/Off Response; RLOAD = 33Ω Figure 12. Shutdown Response; RLOAD = 33Ω 1V/Div VOUT VSDHNN 100µs/Div 1V/Div 200µs/Div Figure 13. Switching Waveforms; RLOAD = 33Ω Figure 14. Efficiency vs. Load Current 95 VOUT (AC Coupled) 100mV/Div 90 VBATT = 3V Efficiency (%) 85 80 75 70 65 1 10 VBATT = 2.5V VBATT = 2V VBATT = 1.5V 500mA IL 2V/Div VLX 10µs/Div 100 1000 Load Current (mA) www.austriamicrosystems.com Revision 1.03 2V/Div VIN 1V/Div VOUT 100mV/Div 6 - 12 AS1320 Data Sheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description The AS1320 is a high-efficiency, compact step-up converter with 35µA 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 15. Block Diagram +1.5 to +3.5V Battery CIN 22µF 4 10µH LX Zero Crossing Detector Startup Circuitry Driver and Control Logic 5 OUT COUT 22µF +3.3V Output – + +1.228V 2 BATT 1 SHDNN Current Limiter VREF – 6 RESETN AS1320 GND 3 +1.1V + 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 real-time-clock supply. The built-in synchronous rectifier significantly improves efficiency and reduces PCB circuit size and costs by eliminating the need for an external Schottky diode. Control Circuitry The AS1320 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 7µs 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. An internal synchronous rectifier eliminates the need for an external Schottky diode, thereby reducing costs and PCB surface area. As the inductor discharges, the P-channel MOSFET turns on and shunts the MOSFET body diode, resulting in a significant reduction of the rectifier voltage drop, improving efficiency without external components. Shutdown When pin SHDNN is low the AS1320 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 PFET. This allows the input battery to provide backup power for devices such as an idle microcontroller, memory, or realtime-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. www.austriamicrosystems.com Revision 1.03 7 - 12 AS1320 Data Sheet - D e t a i l e d D e s c r i p t i o n Low-Battery Cutoff The AS1320 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 batterydetection voltage (see Figure 16). Figure 16. Low-Battery Cutoff Application Diagram +1.5 to +3.5V Battery CIN 22µF 2 BATT 5 OUT R3 100kΩ COUT 22µF +3.3V Output 4 R1 220kΩ L1 10µH LX AS1320 6 RESETN Power-On Reset 1 R2 1MΩ 10nF SHDNN 3 GND For the resistor-divider network shown in Figure 16, calculate the value for R1 by: R1 = R2 x ((VOFF/VSHDNN) - 1) Where: VOFF is the battery voltage at which the AS1320 shuts down. VSHDNN = 1.228V The value of R2 should be between 100kΩ and 1MΩ 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. (EQ 1) Power-On Reset The AS1320 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 100kΩ to 1MΩ 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 Revision 1.03 8 - 12 AS1320 Data Sheet - 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 Inductor Selection The control circuitry of the AS1320 permits a wide range of inductor values to be selected – from 4.7 to 47µH; 10µH 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 AS1320 output power will be reduced. For maximum output current calculate the value for L as: (VBATT(MAX) (1µs))/0.7A < L < (VBATT(MIN)(7µs))/0.7A IOUT(MAX) = [(0.7A/2)(VBATT(MIN) - (0.7A/2)(RNCH + RIND))]/VOUT Where: RIND is the inductor series resistance. RNCH is the RDS(ON) of the N-channel MOSFET (0.3Ω typ). Note: Coils should be able to handle 500mARMS and have a ISAT ≥ 1A and should have a RIND ≤ 100mΩ. (EQ 2) (EQ 3) Capacitor Selection COUT Selection Choose a COUT value to achieve the desired output ripple percentage. A 22µF ceramic capacitor is a good initial value. The value for COUT can be determined by: COUT > (L + 2.5µH) x VBATT(MAX) / r% Where: r is the desired output ripple in %. 2 (EQ 4) 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 AS1320 efficiency. 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 Revision 1.03 9 - 12 AS1320 Data Sheet - 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 AS1320 is available in a 6-pin SOT23 package. Figure 17. 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.φ min and is located above pin 1. 6. Meets JEDEC MO178. Symbol A A1 A2 b C D E E1 L e α Min Max 0.90 1.45 0.00 0.15 0.90 1.30 0.35 0.50 0.08 0.20 2.80 3.00 2.60 3.00 1.50 1.75 0.35 0.55 0.95 REF 0º 10º www.austriamicrosystems.com Revision 1.03 10 - 12 AS1320 Data Sheet - O r d e r i n g I n f o r m a t i o n 11 Ordering Information The AS1320 is available as the standard products shown in Table 4. Table 4. Ordering Information Part AS1320-T Marking ASD7 Description 200mA Step-Up DC-DC Converter Delivery Form Tape and Reel Package 6-pin SOT23 www.austriamicrosystems.com Revision 1.03 11 - 12 AS1320 Data Sheet Copyrights Copyright © 1997-2007, austriamicrosystems AG, Schloss Premstaetten, 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. 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 lifesustaining 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 A-8141 Schloss Premstaetten, 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 Revision 1.03 12 - 12