AS1358_1 AMSCO
Document overview
- Manufacturer or author: Provided By digicamel.com
- PDF pages: 14
Technical content
1 General Description
capacitance ceramic capacitors. rent consumption drops below 500nA. The devices are available in a TSOT23 5-pin package. Figure 1. Typical Application Circuit
2 Key Features
3 Applications
Table 1. Standard Products
4 Pinout
Figure 2. Pin Assignments (Top View) Table 2. Pin Descriptions 1I N Unregulated Input Supply. 3 SHDNN Shutdown. Pull this pin low to disable the LDO.
4 BYPASS
Note: This pin is shorted to GND in shutdown mode. Capacitor Selection and Regulator Stability on page 11 for more details.
5 Absolute Maximum Ratings
Table 3. Absolute Maximum Ratings State Surface Mount Devices”.
6 Electrical Characteristics
Table 4. Electrical Characteristics
- Dropout is defined as VIN - VOUT when VOUT is 100mV below the value of VOUT for VIN = VOUT + 0.5V
- Time needed for VOUT to reach 90% of final value.
SQC (Statistical Quality Control) methods. Table 4. Electrical Characteristics (Continued)
7 Typical Operating Characteristics
VIN = VOUT + 0.5V, CIN = COUT = 1µF, CBYPASS = 10nF, TAMB = 25°C (unless otherwise specified). Figure 3. Output Voltage vs. Input Voltage Figur e 4. Output Voltage Accuracy vs. Load Current Output Voltage Deviation (%) . Figure 5. Output Voltage Accuracy vs. Temperature Figure 6. Dropout Voltage vs. Load Current Output Voltage Deviation (%) . Figure 7. Dropout Voltage vs. Output Voltage
8 Detailed Description
space-limited applications. The devices are available with preset output voltages from 1.5 to 4.5V in 50mV increments. dropout (see Typical Operating Characteristics on page 6). (see Figure 18), and the device output enters a high-impedance state. Note: For normal operation connect pin SHDNN to pin IN. Figure 18. AS1358/AS1359 Block Diagram
1.25 Reference
www.austriamicrosystems.com Revision 1.04 10 - 14 AS1358/AS1359 Datasheet - Detailed Description Current Limit The AS1358/AS1359 include a current limiting circuitry to monitor and control the P-channel MOSFET pass transis- tor’s gate voltage, thus limiting the device output current to 270mA (AS1358) and 510mA (AS1359). Note: See Table 4 on page 4 for the recommended min and max current limits. The output can be shorted to ground indefinitely without causing damage to the device. Thermal Protection Integrated thermal protection circuitry limits total power dissipation in the AS1358/AS1359. When the junction temper- ature (TJ) exceeds +160ºC, the thermal sensor signals the shutdown logic, turning off the P-channel MOSFET pass transistor and allowing the device to cool down. The thermal sensor turns the pass transistor on again after the device’s junction temperature drops by 10ºC, resulting in a pulsed output during continuous thermal-overload condi- tions. Note: Thermal protection is designed to protect the devices in the event of fault conditions. For continuous operation, do not exceed the absolute maximum junction temperature rating of +150ºC. Operating Region and Power Dissipation The AS1358/AS1359 maximum power dissipation is dependant on the thermal resistance of the case and PCB, the temperature difference between the die junction and TAMB, and airflow rate. Power dissipation across the device is calculated as: PD = IOUT (VIN - VOUT)( E Q 1 ) The maximum power dissipation is calculated: PDMAX = (TJ - TAMB)/(θJC + θCA)( E Q 2 ) Where: TJ - TAMB is the temperature difference between the AS1358/AS1359 die junction and the surrounding air; θJC is the thermal resistance of the package; θCA is the thermal resistance through the PC board/copper traces/other materials to the surrounding air. Note: Pin GND of the AS1358/AS1359 provides the electrical connection to system ground and also serves as a heat sink. Connect pin GND to the system ground using a large pad or ground plane. Noise Reduction The AS1358/AS1359 noise bypass circuitry dramatically reduces output noise, exhibiting 9µVRMS of output voltage noise with CBYPASS = 0.01µF and COUT = 1µF. Use an external 0.01µF bypass capacitor between pin BYPASS and pin OUT (see Figure 1 on page 1). Note: Startup time is minimized by internal power-on circuitry which pre-charges CBYPASS.
www.austriamicrosystems.com Revision 1.04 11 - 14 AS1358/AS1359 Datasheet - Application Information
9 Application Information
Capacitor Selection and Regulator Stability For normal operation, use a 1µF capacitor at pin IN and a 1µF capacitor at pin OUT. Larger input capacitor values and lower ESR provide better noise rejection and line-transient response. Reduce output noise and improve load-transient response, stability, and power-supply rejection by using large output capacitors. Note: Some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. With dielectrics such as Z5U and Y5V, it may be necessary to use a 2.2µF or larger output capacitor to ensure stability at tempera- tures below -10°C. With X7R or X5R dielectrics, 1µF is sufficient at all operating temperatures. Bypass Capacitor Use a 0.01µF bypass capacitor at pin BYPASS for low-output voltage noise reduction. The leakage current going into pin BYPASS should be less than 10nA. Increasing the capacitance slightly decreases the output noise. Values above 0.1µF and below 0.001µF are not recommended. Noise, PSRR, and Transient Response The AS1358/AS1359 are designed to deliver ultra-low noise and high PSRR, as well as low dropout and low quiescent currents in battery-powered systems. The power-supply rejection is 92dB at 1kHz and 62dB at 100kHz. (see PSRR vs. Frequency; IOUT = 10mA on page 7). When operating from sources other than batteries, improved supply-noise rejection and transient response can be achieved by increasing the values of the input and output capacitors, and through passive filtering techniques. The Figure 16 and Figure 14 on page 8 show the AS1358/AS1359 line- and load-transient responses. Dropout Voltage The AS1358/AS1359 minimum dropout voltage determines the lowest usable supply voltage. In battery-powered sys- tems, this determines the useful end-of-life battery voltage. Since the AS1358/AS1359 use a P-channel MOSFET pass transistor, the dropout voltage is a function of drain-to- source on-resistance (RDS(ON)) multiplied by ILOAD (see Figure 6 on page 6).
The devices are available in a TSOT23 5-pin package. Figure 19. TSOT23 5-pin Package
- Dimensioning and tolerancing conform to ASME Y14.5M - 1994.
- Dimensions are in millimeters.
- Dimension D does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, and gate burrs shall
trusion shall not exceed 0.15mm per side. Dimensions D and E1 are determined at datum H.
- The package top can be smaller than the package bottom. Dimensions D and E1 are determined at the outer-
The devices are available as the standard products shown in Table 5. Note: All products are RoHS compliant and Pb-free. Table 5. Ordering Information
www.austriamicrosystems.com Revision 1.04 14 - 14 AS1358/AS1359 Datasheet Copyrights Copyright © 1997-2009, 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. 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