AS1325 AMSCO
Document overview
- Manufacturer or author: Provided By digicamel.com
- PDF pages: 17
Technical content
1 General Description
185mA output current (@ 2V VBATT). the supply of real-time-clocks. when the battery voltage falls to a predetermined level. An internal synchronous rectifier is included. The AS1325 is available in a 6-pin SOT23 package. Figure 1. Application Diagram
2 Key Features
3 Applications
4 Pinout
Figure 2. Pin Assignments (Top View) Table 1. Pin Descriptions 0 = The AS1325 is off and the supply current is ≤ 1µA (typ).
5 Absolute Maximum Ratings
Table 2. Absolute Maximum Ratings Solid State Surface Mount Devices”.
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
1 IMAX
TAMB = -40 to +85ºC, VBATT = +2V, VOUT = +5.0, VSHDNN = +1.5V (unless otherwise specified). Typ values @ TAMB = +25ºC.
- Voltage which triggers next loading cycle. Ripple and rms value depend on external components.
Table 4. Electrical Characteristics
- Voltage which triggers next loading cycle. Ripple and rms value depend on external components.
7 Typical Operating Characteristics
Figure 3. VOUT vs. VBATT; On, 16Ω Figure 4. VOUT vs. VBATT; On, 330Ω Figure 5. VOUT vs. VBATT; Shutdown, 300mA Load Figure 6. V OUT vs. VBATT; Shutdown, No Load Figure 7. Maximum Output Current vs. VBATT Figure 8. Startup Voltage vs. Load Resistance Maximum Output Current (mA) .
8 Detailed Description
tions with one- or two-cells, such as lithium ion (Li+), nickel-metal-hydride (NiMH), or alkaline. Figure 27. Block Diagram tery can be used as a battery-backup or real-time-clock supply. The built-in synchronous rectifier significantly improves efficiency. a wide VOUT range without the need for an oscillator. load cycle begins (see Figure 13 on page 7 and Figure 25 on page 9).
VOUT to avoid intermittently switching the device on. Note: If pin SHDNN is not used, it should be connected directly to pin OUT. time-clock, without the usual diode forward drop. In this way a separate backup battery is not needed. CIN and COUT partly determine the size and duration of this spike, as does the current-sink ability of the input device. detection voltage (see Figure 28). Figure 28. Low-Battery Cutoff Application Diagram OFF is the battery voltage at which the AS1325 shuts down. The value of R2 should be between 100kΩ and 1MΩ to minimize battery drain.
www.austriamicrosystems.com Revision 1.01 12 - 17 AS1325 Data Sheet - Detailed Description Power-On Reset The AS1325 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. Antiringing Control If the inductor current falls to zero, an internal 100Ω (typ) antiringing switch is connected from LX to BATT to minimize EMI. The antiringing control can be deactivated by not connecting the pin BATT. The device is supplied by the pin OUT - no supply current flows into pin BATT.
9 Application Information
Note: Coils should be able to handle 500mARMS and have a ISAT ≥ 1A and should have a RIND ≤ 100mΩ. Figure 29. Efficiency Comparison of Different Inductors; F igure 30. Efficiency Comparison of Different Inductors; Table 5. Recommended Inductors
Low ESR capacitors (X5R or X7R) should be used to minimize the output voltage ripple. value for COUT can be used to further reduce ripple and improve AS1325 efficiency. CIN reduces the peak current drawn from the battery and can be the same value as COUT. the IC as possible. Ordinary rectifier diodes must not be used, since the slow recovery rate will compromise efficiency. 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. GND pin directly to the ground plane. Table 6. Recommended Output Capacitor Table 7. Recommended Input Capacitor
The AS1325 is available in a 6-pin SOT23 package. Figure 31. 6-pin SOT23 Package
- All dimensions are in millimeters.
- Foot length is measured at the intercept point between datum
- Package outline exclusive of mold flash and metal burr.
- Pin 1 is the lower left pin when reading the top mark from left
- Pin 1 identifier dot is 0.3mm.φ min and is located above pin 1.
The AS1325 is available as the standard products shown in Table 8. Table 8. Ordering Information
www.austriamicrosystems.com Revision 1.01 17 - 17 AS1325 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, trans- lated, 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. austriami- crosystems 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 tech- nical 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