AS1371 AMSCO
Document overview
- Manufacturer or author: Provided By digicamel.com
- PDF pages: 14
Technical content
1 General Description
3.3V (programmable in 50mV steps). and is qualified for -40°C to +85°C operation.
2 Key Features
3 Applications
hand-held and/or battery-powered device. Figure 1. AS1371 - Typical Application Diagram
4 Pin Assignments
Figure 2. Pin Assignments (Top View) Table 1. Pin Descriptions levels. Leave this pin unconnected if the Power-OK feature is not used. EN 3 Active-High Enable Input. A logic low reduces the supply current to < 1µA. Connect to pin IN for normal operation. the circuit-board ground plane to maximize power dissipation. connected to GND the POK output is related to OUT. OUT 6 LDO Output. Bypass with 1µF to GND.
5 Absolute Maximum Ratings
Table 2. Absolute Maximum Ratings State Surface Mount Devices”. packages is matte tin (100% Sn).
6 Electrical Characteristics
Table 3. Electrical Characteristics
1 IOUT = 100mA 20 50
5 SENSE = GND, VPOKFALLING 90 94 97
SQC (Statistical Quality Control) methods.
- Dropout voltage = VIN - VOUT when VOUT is 100mV < VOUT for VIN = VOUT(NOM) +0.5V (applies only to output
- The rise and fall time of the shutdown signal must not exceed 1ms.
- The delay time is defined as time required to set V
OUT to 95% of its final nominal value.
- The functionality is proven by production test, limits are guaranteed by design.
7 Typical Operating Characteristics
VOUT = 1.8V, VIN = 2.3V, IOUT = 1mA, TAMB = +25°C (unless otherwise specified). Figure 3. Output Voltage vs. Temperature Figure 4. Line Regulation, V OUT vs. VIN; Figure 5. Load Regulation, VOUT vs. IOUT; Figure 6. Quiescent Current vs. Input Voltage Figure 7. POK Voltage Threshold vs. Temperature Figure 8. Dropout Voltage vs. Output Current
8 Detailed Description
3.3V. (see Ordering Information on page 13). 150°C. This is a useful protection when the device is under sustained short circuit conditions. Power-OK detect logic, internal voltage divider, current limiter, thermal sensor and shutdown logic. the output. The output voltage feeds back through an internal resistor voltage divider connected to pin OUT. Figure 13. AS1371 - Block Diagram the nominal output (see Ordering Information on page 13). Non-standard devices are available.
www.austriamicrosystems.com Revision 1.04 9 - 14 AS1371 Datasheet - Detailed Description Power-OK and Low-Battery-Detect Functionality The AS1371’s power-ok or low-battery-detect circuitry is built around an N-channel MOSFET. The circuitry monitors the voltage on pin SENSE and if the voltage goes out of r egulation (e.g. during dropout, current limit or thermal shutdown) the pin POK goes low. The pin SENSE can be conne cted to a resistive-divider to monitor a particular definable voltage and compare it with an internal voltage reference. If the SENSE pin is connected to GND an internal resistive-divider is activated and connecte d 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 = 1.2V. 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 from pin POK to pin OUT. Large r values for this resistor will help to minimize current consumption; a 100kΩ resistor is perfect for most applications (see Figure 1 on page 1). For the circuit shown in the left of Figure 14 on page 11, the input bias current into SENSE 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: Where: In case of the SENSE pin is connected to GND, an internal resistor-divider network is activated and compares the out- put voltage with a 94% (typ.) voltage threshold. For this particular Power-OK application, no external resistive compo- nents are necessary. Current Limiting The AS1371 include current limiting circuitry to protect agai nst short-circuit conditions. The circuitry monitors and controls the gate voltage of the P-channel MOSFET, lim iting the output current to 400mA. The P-channel MOSFET output can be shorted to ground for an indefinite period of time without damaging the device. Thermal-Overload Protection The devices are protected against therma l runaway conditions by the integrated thermal sensor circuitry. Thermal shutdown is an effective instrument to prevent die overheating since the power transistor is the principle heat source in the device. If the junction temperature exceeds 150ºC with 15ºC hysteresis, the thermal sensor starts the shutdown logic, at which point the P-channel MOSFET is switched off. After the device temperature has dropped by approximately 15ºC, the thermal sensor will turn the P-channel MOSFET on again. Note that this will be exhibited as a pulsed output under continuous thermal-overload conditions. Note: The absolute maximum junction-temperature of +150ºC should not be exceeding during continual operation. (EQ 1)R1 R2 VIN VSENSE ⎛⎞×=
www.austriamicrosystems.com Revision 1.04 10 - 14 AS1371 Datasheet - Detailed Description Operating Region and Power Dissipation Maximum power dissipation is determined by the thermal resi stance of the case and circ uit board, the temperature difference between the die junction and ambient air, and the rate of air flow. The power dissipation of the device is calculated by: Maximum power dissipation is calculated by: Where: TJ - TAMB is the temperature difference between the device die junction and the surrounding air. θJB is the thermal resistance of the package. θJA is the thermal resistance through the circuit board, copper traces, and other materials to the surrounding. Note: Pin GND is a multi-function pin providing a connection to the system ground and acting as a heat sink. This pin should be connected to the system ground using a large pad or a ground plane. (EQ 2)PI OUT VIN VOUT–()×= (EQ 3)PMAX TJ TAMB–
9 Application Information
reduce noise and improve load transient-response, stability and power-supply rejection. Note: Some ceramic capacitors exhibit large capacitance and ESR variations with variations in temperature. output bypass capacitors, which are shown in Figure 14. The Section 6 Electrical Characteristics on page 4 show also the device line- and load-transient responses. RDS(ON) is the drain-to-source on -resistance. Figure 14. Application Diagrams
The device is available in a 6-pin 2x2 TDFN package. Figure 15. 6-pin 2x2 TDFN package Diagram
- Dimensioning and tolerancing conform to ASME Y14.5M-1994.
- All dimensions are in millimeters, angle is in degrees.
- N is the total number of terminal.
- ND and NE refers to the number of terminals on each side respectively.
- Terminal #1 identifier and terminal numbering convention shall conform to JESD 95-1 SPP-012. Details of ter-
either a mold, embedded metal or mark feature.
- Dimension b applies to metallized terminal and is measured between 0.15 and 0.30mm from terminal tip.
- Unilateral coplanarity zone applies to the exposed heat sink slug as well as the terminals.
Table 4. 6-pin 2x2 TDFN package Dimensions
The device is available as the standard products listed in Table 5. Note: All products are RoHS compliant and Pb-free. Table 5. Ordering Information
www.austriamicrosystems.com Revision 1.04 14 - 14 AS1371 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 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 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