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| BQ8211 Low Dropout 300mA Voltage Regulator with Enable Product Specification Revision 1.3 September 13, 2006 General Description The BQ8211 is a low dropout voltage regulator capable of delivering 300 mA to the load. It is adjustable and can set a precise voltage from 1.175V to 15V with two external resistors. The BQ8211 meets all specifications down to 1.175V output, unlike CMOS LDO's which loose performance with outputs below 2.25V. The enable pin provides a remote turn-off for low power consumption. It draws virtually zero current while in shutdown mode. To assure accuracy within 2% over temperature, the heart of the BQ8211 is a self-correcting AcuRefTM bandgap reference. On-chip current limit and thermal shutdown with hysteresis protects against any combination of overload and ambient temperature that might cause the junction temperature to exceed safe limits. Applications * Graphic cards and PC motherboards * Cell Phones * DVD video player Replacement for: * LX8211 Features * Low dropout voltage (980mV at 300 mA) * Enable pin implements sequencing * Vout tolerance less than 2 % over * * * * * * temperature Featured in the very small SOT-23 package Stable with low cost 1F capacitor Low ground current Thermal protection with hysteresis Short circuit protection RoHS compliant available Typical Application www.acutechnology.com BQ8211 Acutechnology Semiconductor Inc. BQ8211 Pin Configuration Pin Descriptions Pin Name VIN Ground ENABLE Adjust VOUT Function + Unregulated Input Voltage, Collector of Pass Transistor - Ground Active high, ENABLE > 1 V OFF low, ENABLE < 0.25V Adjust input. Connect to resistive feed back divider. Regulated Output Functional Block Diagram www.acutechnology.com 2 Rev. 1.3 September 13, 2006 Acutechnology Semiconductor Inc. BQ8211 Ordering Information Device BQ8211 BQ8211 BQ8211 BQ8211 BQ8211 BQ8211 BQ8211 BQ8211 Note: The Operating Tj 0C 125C 0C 125C 0C 125C 0C 125C 0C 125C 0C 125C 0C 125C 0C 125C %Tol 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 PKG Type SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5 VOUT 1.8V 1.8V 2.5V 2.5V 3.3V 3.3V ADJ ADJ Wrap T&R T&R T&R T&R T&R T&R T&R T&R Ordering Number BQ8211CY-M5-18-TR BQ8211CY-M5-18-TRL BQ8211CY-M5-25-TR BQ8211CY-M5-25-TRL BQ8211CY-M5-33-TR BQ8211CY-M5-33-TRL BQ8211CY-M5-AJ-TR BQ8211CY-M5-AJ-TRL TRL parts are Lead Free and RoHS compliant. Absolute Maximum Ratings Stress greater than those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These stress ratings only, and functional operation of the device at these or any conditions beyond those indicated under recommended Operating Conditions is not implied. Exposure to "Absolute Maximum Rating" for extended periods may affect device reliability. Use of standard ESD handling precautions is required. Parameter Maximum VIN Maximum VENABLE Power Dissipation (Internally limited) Maximum Junction Temperature Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, 4 sec.) SOT- 23-5 package 150 -40 to 125 -65 to 150 300 C C C C Value 18 Vin + 0.3V Units Volts Volts Thermal Management Thermal Resistance (Junction to Ambient) SOT-23-5 (minimum foot print) Typical Value 220 Typical Value 170 Units C/W Units C/W Thermal Resistance (Junction to Ambient) SOT-23-5 (Soldered to 1 in2 1 oz. copper PCB) www.acutechnology.com 3 Rev. 1.3 September 13, 2006 Acutechnology Semiconductor Inc. BQ8211 Electrical Specifications Electrical characteristics are guaranteed over the full temperature range 40C www.acutechnology.com 4 Rev. 1.3 September 13, 2006 Acutechnology Semiconductor Inc. BQ8211 Application Notes www.acutechnology.com 5 Rev. 1.3 September 13, 2006 Acutechnology Semiconductor Inc. BQ8211 Application Notes 1. Typical Application Notes: 1. Output voltage is 1.175V * (R1 +R2)/R2 2. Input and output capacitors should be located close to the device. 3. The BQ8211 will remain stable with C2 and C3 as low as 1.0 F. Overall transient performance is improved with increased capacitance. 4. The output is fully enabled when Enable is above 1V. EN may be driven by either a digital or analog signal to control turn-on time. 2. Stability A Vin Capacitor is also recommended. A 1F capacitor is a bypassing for almost all applications. A larger capacitor is also suitable depending on the cleanliness of the VIN source. The Output capacitor is critical in maintaining regular stability. The BQ8211 is stable with an output capacitor greater than 1F. Any increase of the output capacitor will merely improve the loop stability and the load transient response. Tantalum Capacitors exhibit the best stability over a wide range of loads and are recommended. www.acutechnology.com 6 Rev. 1.3 September 13, 2006 Acutechnology Semiconductor Inc. BQ8211 3. Output Voltage The BQ8211 meets all specifications down to 1.175V output. It does not suffer from performance degradation issues such as experienced with CMOS LDO's. The BQ8211 develops a 1.175V reference voltage between the adjust pin terminal and ground. This voltage is applied across the resistor R2 to generate a constant current (I2). The current from the adjust terminal could introduce error to the output, but since it is very small (<0.5A) compared with the current I2 and very constant with line and load changes, the error can be ignored. The constant current I2 then flows through resistor R1 and sets the output voltage to the desired level. The BQ8211 regulates the voltage that appears between its output and ground pins or between its adjust and ground pins. In some cases, line resistances can introduce errors to the voltage across the load. To obtain the best load regulation a few precautions are needed. For example, it is important to minimize the line resistances to the load. So, the load itself should be tied directly to the output terminal on the positive side and directly to the ground terminal on the negative side. The best performance is obtained with the positive side of the resistor R1 tied near the load and with the ground side of the resistor R2 tied near the ground of the regulator. This will provide remote output sensing which will optimize regulation at the load. 4. Enable/Sequencing The BQ8211 provides an enable function. The EN pin has to be at least 1V for the device to be fully turned on. When the voltage of the EN pin is low the device is in shutdown mode and it will not draw any current from the VIN terminal. 5. Protection Diodes Unlike older regulators, the BQ8211 requires no protection diodes between the ADJ pin and VOUT or from the VOUT to the VIN to prevent over-stressing the die. Internal resistors are limiting the internal current paths on the ADJ pin. Therefore, even with capacitors on the ADJ pin, no protection diode is needed to ensure device safety under short circuit conditions. External diodes between the VIN and VOUT are not usually needed. Only if high value output capacitors are used (> 1000uF) and the input is instantaneously shorted to ground, can damage occur. 6. Thermal Considerations When an integrated circuit operates with an appreciable current, its junction temperature is elevated. It is important to quantify its thermal limits in order to achieve acceptable performance and reliability. This limit is determined by summing the individual parts consisting of a series of temperature rises from the semiconductor junction to the operating environment. The heat generated at the device junction flows through the die to the die attach pad, through the lead frame to the surrounding case material, to the printed circuit board, and eventually to the ambient environment. www.acutechnology.com 7 Rev. 1.3 September 13, 2006 Acutechnology Semiconductor Inc. BQ8211 The BQ8211 regulators have internal thermal shutdown to protect the device from overheating. Under all possible operating conditions, the junction temperature of the BQ8211 must be lower than 125C. A heatsink may be required depending on the maximum power dissipation and maximum ambient temperature of the application. To determine if a heatsink is needed, the power dissipated by the regulator, PD, must be calculated: PD= (Vc-VOUT) IL where the IL is the load current. The next parameter, which must be calculated, is the max. allowable temperature rise, T(max): T(max)=TJ(max)-TA(max) where TJ(max) is the maximum allowable junction temperature (125C), and TA(max) is the maximum ambient temperature, which will be encountered in the application. Using the calculated values for T(max) and PD, the maximum allowable value for the junction to ambient thermal resistance (JA) can be calculated: JA=T(max)/ PD If the maximum allowable value for JA is found to be greater than the junction to ambient thermal resistance for the package used, no heatsink is needed since the package alone will dissipate enough heat to satisfy these requirements. Contact Information Acutechnology Semiconductor Inc. 3487 McKee Rd. Suite 52 San Jose CA , USA 95127 Disclaimer The information furnished by Acutechnology in this data sheet is believed to be accurate and reliable. However, Acutechnology assumes no responsibility for its use. Acutechnology reserves the right to change circuitry and specifications at any time without notification to the customer. TEL: FAX: website: (408) 259-2300 (408) 259-9160 www.acutechnology.com Life Support Policy Acutechnology Products are not designed or authorized for use as components in life support devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. AcuRef is a trademark of Acutechnology Semiconductor Inc www.acutechnology.com 8 Rev. 1.3 September 13, 2006 Acutechnology Semiconductor Inc. BQ8211 www.acutechnology.com 9 Rev. 1.3 September 13, 2006 |
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