AQ8211 ACUTECH | Alldatasheet

Document overview

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Technical content

Features

  • Extended Temp Range -40C˚ ≤ 125C˚
  • Low dropout voltage (350mV at 500 mA)
  • Enable pin implements sequencing
  • Reverse current protection
  • Featured in the very small SOT-23 package
  • Stable with low cost 1µF capacitor
  • Low ground current <100 µA
  • Thermal protection with hysteresis
  • Short circuit protection
  • RoHS compliant Typical Application

Acutechnology Semiconductor Inc. AQ8211 www.acutechnology.com 2 Rev. 2.1 January 22, 2006 Pin Configuration Pin Descriptions Pin Name Function VIN + Unregulated Input Voltage, Collector of Pass Transistor Ground - Ground ENABLE Active high, ENABLE > (0.95V + VOUT), Chip bias circuit supply OFF low, ENABLE < 0.25V Adjust Adjust input. Connect to resistive feed back divider. VOUT Regulated Output Functional Block Diagram

Acutechnology Semiconductor Inc. AQ8211 www.acutechnology.com 3 Rev. 2.1 January 22, 2006

Ordering Information

Device Operating Tj %Tol PKG Type V OUT Wrap Ordering Number AQ8211 -40C ˚ ≤ 125C˚ 1.0 SOT-23-5 1.8V T&R AQ8211AY-M5-18-TRL AQ8211 -40C ˚ ≤ 125C˚ 1.0 SOT-23-5 2.5V T&R AQ8211AY-M5-25-TRL AQ8211 -40C ˚ ≤ 125C˚ 1.0 SOT-23-5 3.3V T&R AQ8211AY-M5-33-TRL AQ8211 -40C ˚ ≤ 125C˚ 1.0 SOT-23-5 ADJ T&R AQ8211AY-M5-AJ-TRL Note: The 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 devic e 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 reliab ility. Use of standard ESD handling precautions is required. Parameter Value Units Maximum VIN 18 Volts Maximum VENABLE 18 Volts Power Dissipation (Internally limited) Maximum Junction Temperature 150 °C Operating Junction Temperature Range -40C ˚ ≤ 125C˚ °C Storage Temperature Range -65 to 150 °C Lead Temperature (Soldering, 4 sec.) SOT- 23-5 package 300 °C Thermal Management Thermal Resistance (Junction to Ambient) Typical Value Units SOT-23-5 (minimum foot print) 220 °C/W Thermal Resistance (Junction to Ambient) Typical Value Units SOT-23-5 (Soldered to 1 in2 1 oz. copper PCB) 170 °C/W

Acutechnology Semiconductor Inc. AQ8211 www.acutechnology.com 4 Rev. 2.1 January 22, 2006 Electrical Specifications Electrical characteristics are guaranteed over the full temperature range -40ºC <Tj< 125ºC. Ambient temperature must be de-rated based upon power dissipation and package thermal characteristics. Unless otherwise specified: VENABLE = VIN = (VOUT + 1.5V), IOUT = 10 mA, Tj = 25C. Values in bold are over the full temperature range. Symbol Parameter Conditions Min Typ Max Units -1 V OUT +1 % VOUT Output Voltage (1) LNREG Line Regulation (1) ∆VEN = VOUT + (1.5V to 10V) 0.035 0.2 % LDREG Load Regulation (1) ∆IOUT = (10mA to 250 mA) 0.2 0.4 % IOUT = 100 mA 50 80 mV IOUT = 250 mA 150 200 mV VD Dropout Voltage (1, 2) IOUT = 500 mA 300 350 mV ISC Current Limit (1) V EN-VOUT = 2V 600 800 mA IGND Ground Current ON 100 150 µA IGND Ground Current ON (5) Adjustable version 65 100 µA VIL Enable Pin Voltage (OFF) With respect to GND 0.25 0.45 V VIH Enable Pin Voltage (ON) With respect to V OUT 0.92 0.95 V IOUT = 10 mA 0.3 0.5 mA IOUT = 250 mA 1.8 3.0 mA IENON Enable Current ON IOUT = 500 mA 3.8 5.0 mA Adjustable version only 1.208 1.220 1.232 V VADJ Reference Voltage -40°C ≤Tj ≤ 125°C 1.202 1.238 V IQMIN Minimum Load Current (5) To maintain regulation 0.5 2.0 mA TC Temperature Coefficient 0.005 %/°C TS Temperature Stability 0.5 %/°C VN RMS Output Noise (3) 0.003 % VOUT PSRR Ripple Rejection Ratio (4) Vin = 5V 60 72 dB TSD Thermal Shutdown Junction Temperature 150 °C TSDHYST TSD Hysteresis 25 °C Notes: (1) Low duty cycle pulse testing with Kelvin connections required. (2) Measure (V IN - VOUT) when ∆VOUT, OR ∆VREF = 1% (3) Bandwidth of 10Hz to 10kHz (4) 120Hz input ripple (5) Adjustable version only

Acutechnology Semiconductor Inc. AQ8211 www.acutechnology.com 5 Rev. 2.1 January 22, 2006 Application Notes

Acutechnology Semiconductor Inc. AQ8211 www.acutechnology.com 6 Rev. 2.1 January 22, 2006 Application Notes 1. Typical Application Notes: 1. Output voltage is 1.22V * (R1 +R2)/R2 2. Input and output capacitors should be located close to the device. 3. The AQ8211 will remain stable with C1 and C3 as low as 0.1 µF and 1.0 µF respectively. Overall transient performance is improved with increased capacitance and the addition of C2. 4. The output is fully enabled when E nable is 950 mV above the expected V OUT. EN may be driven by either a digital or analog signal to control either turn-on time or to give full control of risetime. 5. Enable, tied to any separate source >0.95V + V OUT, will insure Ultra-low drop out voltage (350mV@ 500mA) 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 100nF capacitor is a suitable input bypass for almost all applications. A larger capacitor is also suitable depending on the cleanliness of the Enable source. A Vin Capacitor is also recommended. A 1µF capacitor is a bypassing for almost all applications. A larger capacitor is also suitable depending on the cleanliness of the V IN source. The Output capacitor is critical in maintaining regular stability. The AQ8211 is stable with an output capacitor greater than 1µF. 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. 3. Output Voltage The AQ8211 meets all specifications down to 1.22V output. It does not suffer from performance degradation issues such as experienced with CMOS LDO’s. Drop out voltage will be less than 350 mV at 500 mA load with the ENABLE pin held greater than 0.95V + Vout.

Acutechnology Semiconductor Inc. AQ8211 www.acutechnology.com 7 Rev. 2.1 January 22, 2006 The AQ8211 develops a 1.22V 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 (<0.5µA) 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 AQ8211 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 AQ8211 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. OUT ENABLE 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. 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.

Acutechnology Semiconductor Inc. AQ8211 www.acutechnology.com 8 Rev. 2.1 January 22, 2006 To this end, the AQ8211 allows for an analog control of the output voltage via the ENABLE pin. This allows for sequential, ratio-metric and simultaneous sequencing schemes. 5. Protection Diodes Unlike older regulators, the AQ8211 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. The AQ8211 regulators have internal thermal shutdown to protect the device from over- heating. Under all possible operating conditions, the junction temperature of the AQ8211 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, P D, 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 (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. 7. Ultra low Dropout Operation The AQ8211 allows for ultra low dropout operation by connecting the pin ENABLE to >0.95V + Vout. This results in a dropout of 350 mV at 500 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.

Acutechnology Semiconductor Inc. AQ8211 www.acutechnology.com 9 Rev. 2.1 January 22, 2006 Package Dimensions

Acutechnology Semiconductor Inc. AQ8211 www.acutechnology.com 10 Rev. 2.1 January 22, 2006 Contact Information Acutechnology Semiconductor Inc. TEL: (408) 259-2300 3487 McKee Rd. Suite 52 FAX: (408) 259-9160 San Jose CA , USA 95127 website: www.acutechnology.com Disclaimer The information furnished by Acutechnology in this data s heet 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. 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 ex pected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended fo r surgical implant into the body or (b) support or sustain life, and whose failure t o perform can be reasonably expected to result in a significant injury to the user. AcuRef is a trademark of Acutechnology Semiconductor Inc