AQ112CY-S4-AJ-TR

AQ112 Ultra-Low Dropout 1A Voltage Regulator Product Specification Revision 1.6 September 13, 2006 General Description The AQ112 is an ultra-low dropout three terminal voltage regulator, offered in popular fixed options or an adjustable version that can set a precise voltage from 1.22V to 12V with two external resistors. It drops into the footprint of the popular LM1117 SOT-223 and provides a true 4th pin separated from the output tab which allows a separate bias connection from the pass transistor in order to achieve enable and ultra low dropout from VIN to VOUT. The enable pin provides a remote turn-off for low power consumption. It draws virtually zero current in shutdown mode and implements Sequential, Ratiometric, or Simultaneous sequencing schemes. To assure accuracy within 1%, the heart of the AQ112 is a self-correcting AcuRef™ 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 • PC motherboards • Switching power supply post-regulation • Telecom equipment • DVD video player Features • Ultra Low Dropout (400mV at 1A) • Enable pin implements sequencing • Vout tolerance less than 1.5% over • • • • • • temperature Stable with low cost 1uF capacitor Thermal protection with hysteresis Short circuit protection Adjustable output The AQ112 is featured in the new SOT223 4-lead TetraPackTM package. RoHS compliant available Typical Application www.acutechnology.com AQ112 Acutechnology Semiconductor Inc. AQ112 Pin Configuration Pin Descriptions Pin Name VIN ENABLE Ground/Adjust VOUT Function + Unregulated Input Voltage, Collector of Pass Transistor Active high, ENABLE > (0.95V + VOUT), Chip bias circuit supply OFF low, ENABLE < 0.25V Ground or Adjust pin (Connect to resistive feed back divider) Regulated Output Functional Block Diagram www.acutechnology.com 2 Rev. 1.6 September 13, 2006 Acutechnology Semiconductor Inc. AQ112 Ordering Information Device AQ112 AQ112 AQ112 AQ112 AQ112 AQ112 AQ112 AQ112 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-223-4 SOT-223-4 SOT-223-4 SOT-223-4 SOT-223-4 SOT-223-4 SOT-223-4 SOT-223-4 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 AQ112CY-S4-18-TR AQ112CY-S4-18-TRL AQ112CY-S4-25-TR AQ112CY-S4-25-TRL AQ112CY-S4-33-TR AQ112CY-S4-33-TRL AQ112CY-S4-AJ-TR AQ112CY-S4-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, 4sec.) SOT- 223 package 150 0 to 125 -65 to 150 300 °C °C °C °C Value 18 18 Units Volts Volts Thermal Management Thermal Resistance (Junction to TAB) SOT-223 Thermal Resistance (Junction to Ambient) SOT-223 (tab soldered to 1 in2 1 oz. copper PCB) Typical Value 15 Typical Value 46 Units °C/W Units °C/W www.acutechnology.com 3 Rev. 1.6 September 13, 2006 Acutechnology Semiconductor Inc. AQ112 Electrical Specifications Electrical characteristics are guaranteed over the full temperature range 0ºC 0.95V + VOUT, will insure Ultra-low drop out voltage (400mV@ 1A) from VIN to VOUT. Or, Enable, tied to Vin will support a low drop out voltage (0.95V). 2. Stability An Enable capacitor is recommended. A 1.0 µF capacitor on VIN is a suitable input bypass for almost all applications. A larger capacitor is also suitable. In the adjustable version the “adjust” terminal can be bypassed to ground with a bypass capacitor (CADJ) to improve ripple rejection. This bypass capacitor prevents ripple from being amplified as the output voltage is increased. At any ripple frequency, the impedance of the CADJ should be less than R1 (being R1 the resistor between the output and the adjust pin) to prevent the ripple from being amplified: Z = 1/(2π*fRIPPLE* CADJ) < R1 R1 is normally in the range of 1KΩ. The output capacitor is critical in maintaining regular stability. The AQ1541 is stable with an output capacitor greater than 1.0 µF. Of course any increase of the output capacitor will merely improve the loop stability and the load transient response. In the case of the adjustable regulator, when the CADJ is used, a larger output capacitance may be required. The capacitor C3 may also be necessary if large ripple is present on the VIN line. Tantalum Capacitors exhibit the best stability over a wide range of loads and are recommended. www.acutechnology.com 6 Rev. 1.6 September 13, 2006 Acutechnology Semiconductor Inc. AQ112 3. Output Voltage The AQ112 adjustable version develops a 1.22V reference voltage between the output and the adjust pin terminal. This voltage is applied across the resistor R1 to generate a constant current (I1). The current from the adjust terminal could introduce error to the output, but since it is very small (< 20µA) compared with the current I1 and very constant with line and load changes, the error can be ignored. The constant current I1 then flows through resistor R2 and sets the output voltage to the desired level. For fixed voltages the resistor R1 and R2 are integrated inside the devices. The AQ112 regulates the voltage that appears between its output and ground pins or between its output and adjust 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. When the adjustable regulator is used, the best performance is obtained with the positive side of the resistor R1 tied directly to the output terminal of the regulator rather than near the load. This will eliminate line drops from appearing effectively in series with the reference and degrading regulation. In addition the ground side of the resistor R2 can be returned near the ground of the load to provide remote ground sensing and improve load regulation. A capacitor (470pF) between the ADJ pin and system ground will enhance stability. 4. Enable/Sequencing The AQ112 provides an enable function. The EN pin has to be at least 950 mV higher than the output voltage 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. E NABLE O UT 0 FIG.2 ENABLE 0-5V, Output follows to 3.3V out (1V/div vertical, 200us/div horizontal) In addition the enable function includes a sequencing feature, because when the enable pin ramps in voltage the output voltage follows (it will be around 900 mV less than the enable voltage until it reaches the regulation voltage) as shown in Fig. 2 above. www.acutechnology.com 7 Rev. 1.6 September 13, 2006 Acutechnology Semiconductor Inc. AQ112 In applications where multiple regulated supply rails are required, it is often required that the relationship between the various supply voltages be controlled during start-up and shutdown. To this end, the AQ112 allows for an analog control of the output voltage via the ENABLE pin. This allows for sequential, ratio-metric and simultaneous sequencing schemes. 4. Protection Diodes Unlike older regulators, the AQ112 family does not need any protection diodes between the adjustment pin and output or from the output to the input to prevent over-stressing the die. Internal resistors are limiting the internal current paths on the adjustment pin. Therefore, even with capacitors on the adjustment pin, no protection diode is needed to ensure device safety under short circuit conditions. External diodes between the input and output are not usually needed. Only if high value output capacitors are used (> 1000uF) and the input is instantaneously shorted to ground, can damage occur. 5. 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. The AQ112 regulators have internal thermal shutdown to protect the device from overheating. Under all possible operating conditions, the junction temperature of the AQ112 must be lower than 125°C. 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 maximum allowable temperature rise, T(max): T(max)=TJ(max)-TA(max) where TJ(max) is the maximum allowable junction temperature (125°C), 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 (θJA) can be calculated: θJA=T(max)/ PD If the maximum allowable value for θJA 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. www.acutechnology.com 8 Rev. 1.6 September 13, 2006 Acutechnology Semiconductor Inc. AQ112 7. Ultra low Dropout Operation The AQ112 allows for ultra low dropout operation by connecting the pin ENABLE to >0.95V + Vout. This results in a dropout of 100 mV at 150 mA of load current, between Vin and VOUT. This feature is important when the supply voltage is dropping near the output regulated voltage. Furthermore if the voltage dropout is low, the internal power dissipation is also reduced and the thermal requirements of the device are less stringent. www.acutechnology.com 9 Rev. 1.6 September 13, 2006 Acutechnology Semiconductor Inc. AQ112 Package Dimensions SOT223-4 TetraPackTM 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. TetraPack and AcuRef are trademarks of Acutechnology Semiconductor Inc www.acutechnology.com 10 Rev. 1.6 September 13, 2006