Ultra-Low Dropout 500mA Voltage Regulator with Enable Product Spe

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Ultra-Low Dropout 500mA Voltage Regulator with Enable Product Spe

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AQ8211
Ultra-Low Dropout 500mA Voltage Regulator with Enable
Product Specification Revision January 2007
AQ8211 ultra-low dropout voltage regulator capable delivering load. adjustable precise voltage from 1.22V with external resistors. AQ8211 meets specifications down 1.22V output, unlike CMOS LDO's which loose performance with outputs below 2.25V. enable provides remote turn-off power consumption. draws virtually zero current shutdown mode implements Sequential, Ratiometric, Simultaneous sequencing schemes. This also allows separate bias connection from pass transistor order achieve ultra dropout from VOUT. Reverse current protection blocks current flowing from VOUT when AQ8211 disabled. current flows. assure accuracy over temperature, heart AQ8211 self-correcting AcuRefbandgap reference. On-chip current limit thermal shutdown with hysteresis protects against combination overload ambient temperature that might cause junction temperature exceed safe limits.
Applications Graphic cards motherboards Cell Phones video player Replacement for: LX8211 Features Extended Temp Range -40C° 125C° dropout voltage (350mV Enable implements sequencing Reverse current protection Featured very small SOT-23
package Stable with cost capacitor ground current <100 Thermal protection with hysteresis Short circuit protection RoHS compliant
Typical Application
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AQ8211
Acutechnology Semiconductor Inc.
AQ8211
Configuration
Descriptions
Name Ground ENABLE Adjust VOUT Function Unregulated Input Voltage, Collector Pass Transistor Ground Active high, ENABLE (0.95V VOUT), Chip bias circuit supply low, ENABLE 0.25V Adjust input. Connect resistive feed back divider. Regulated Output
Functional Block Diagram
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Acutechnology Semiconductor Inc.
AQ8211
Ordering Information
Device AQ8211 AQ8211 AQ8211 AQ8211
Note:
Operating -40C° 125C° -40C° 125C° -40C° 125C° -40C° 125C°
%Tol
Type SOT-23-5 SOT-23-5 SOT-23-5 SOT-23-5
VOUT 1.8V 2.5V 3.3V
Wrap
Ordering Number AQ8211AY-M5-18-TRL AQ8211AY-M5-25-TRL AQ8211AY-M5-33-TRL AQ8211AY-M5-AJ-TRL
parts Lead Free RoHS compliant.
Absolute Maximum Ratings
Stress greater than those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these conditions beyond those indicated under recommended Operating Conditions implied. Exposure "Absolute Maximum Rating" extended periods affect device reliability. standard handling precautions required. Parameter Maximum Maximum VENABLE Power Dissipation (Internally limited) Maximum Junction Temperature Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, sec.) SOT- 23-5 package -40C° 125C° Value Units Volts Volts
Thermal Management
Thermal Resistance (Junction Ambient) SOT-23-5 (minimum foot print) Typical Value Typical Value Units °C/W Units °C/W
Thermal Resistance (Junction Ambient) SOT-23-5 (Soldered copper PCB)
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AQ8211
Electrical Specifications
Electrical characteristics guaranteed over full temperature range <Tj< Ambient temperature must de-rated based upon power dissipation package thermal characteristics. Unless otherwise specified: VENABLE (VOUT 1.5V), IOUT 25C. Values bold over full temperature range. Symbol VOUT LNREG LDREG Parameter Output Voltage Line Regulation Load Regulation Conditions -40°C 125°C VOUT (1.5V 10V) IOUT (10mA IOUT Dropout Voltage IOUT IOUT IGND IGND Current Limit Ground Current Ground Current Enable Voltage (OFF) Enable Voltage (ON) Adjustable version With respect With respect VOUT IOUT IENON Enable Current IOUT IOUT VADJ IQMIN PSRR TSDHYST Reference Voltage Minimum Load Current Temperature Coefficient Temperature Stability Output Noise Ripple Rejection Ratio Thermal Shutdown Hysteresis Junction Temperature Adjustable version only -40°C 125°C maintain regulation 1.208 1.202 0.005 0.003 0.25 VEN-VOUT -1.5 VOUT VOUT 0.035 0.45 0.92 1.220 0.95 1.232 1.238 +1.5 Units %/°C %/°C VOUT
Notes: duty cycle pulse testing with Kelvin connections required. Measure (VIN VOUT) when VOUT, VREF Bandwidth 10Hz 10kHz 120Hz input ripple Adjustable version only
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Acutechnology Semiconductor Inc.
AQ8211
Application Notes
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Rev.
January 2006
Acutechnology Semiconductor Inc.
AQ8211
Application Notes
Typical Application
Notes: Output voltage 1.22V +R2)/R2 Input output capacitors should located close device. AQ8211 will remain stable with respectively. Overall transient performance improved with increased capacitance addition output fully enabled when Enable above expected VOUT. driven either digital analog signal control either turn-on time give full control risetime. Enable, tied separate source >0.95V VOUT, will insure Ultra-low drop voltage (350mV@ 500mA) from VOUT. Enable, tied will support drop voltage (0.95V).
Stability
Enable capacitor recommended. 100nF capacitor suitable input bypass almost applications. larger capacitor also suitable depending cleanliness Enable source. Capacitor also recommended. capacitor bypassing almost applications. larger capacitor also suitable depending cleanliness source. Output capacitor critical maintaining regular stability. AQ8211 stable with output capacitor greater than 1µF. increase output capacitor will merely improve loop stability load transient response. Tantalum Capacitors exhibit best stability over wide range loads recommended.
Output Voltage
AQ8211 meets specifications down 1.22V output. does suffer from performance degradation issues such experienced with CMOS LDO's. Drop voltage will less than load with ENABLE held greater than 0.95V Vout.
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AQ8211
AQ8211 develops 1.22V reference voltage between adjust terminal ground. This voltage applied across resistor generate constant current (I2). current from adjust terminal could introduce error output, since very small (<0.5µA) compared with current very constant with line load changes, error ignored. constant current then flows through resistor sets output voltage desired level. AQ8211 regulates voltage that appears between output ground pins between adjust ground pins. some cases, line resistances introduce errors voltage across load. obtain best load regulation precautions needed. example, important minimize line resistances load. load itself should tied directly output terminal positive side directly ground terminal negative side. best performance obtained with positive side resistor tied near load with ground side resistor tied near ground regulator. This will provide remote output sensing which will optimize regulation load.
Enable/Sequencing
AQ8211 provides enable function. least higher than output voltage device fully turned When voltage device shutdown mode will draw current from terminal.
ENABLE
FIG.2 ENABLE 0-5V, Output follows 3.3V (1V/div vertical, 200us/div horizontal) addition enable function includes sequencing feature, because when enable ramps voltage output voltage follows will around less than enable voltage until reaches regulation voltage) shown Fig. above. applications where multiple regulated supply rails required, often required that relationship between various supply voltages controlled during start-up shutdown.
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AQ8211
this end, AQ8211 allows analog control output voltage ENABLE pin. This allows sequential, ratio-metric simultaneous sequencing schemes.
Protection Diodes
Unlike older regulators, AQ8211 requires protection diodes between VOUT from VOUT prevent over-stressing die. Internal resistors limiting internal current paths pin. Therefore, even with capacitors pin, protection diode needed ensure device safety under short circuit conditions. External diodes between VOUT usually needed. Only high value output capacitors used 1000uF) input instantaneously shorted ground, damage occur.
Thermal Considerations
When integrated circuit operates with appreciable current, junction temperature elevated. important quantify thermal limits order achieve acceptable performance reliability. This limit determined summing individual parts consisting series temperature rises from semiconductor junction operating environment. heat generated device junction flows through attach pad, through lead frame surrounding case material, printed circuit board, eventually ambient environment. AQ8211 regulators have internal thermal shutdown protect device from overheating. Under possible operating conditions, junction temperature AQ8211 must lower than 125°C. heatsink required depending maximum power dissipation maximum ambient temperature application. determine heatsink needed, power dissipated regulator, must calculated: (Vc-VOUT) where load current. next parameter, which must calculated, max. allowable temperature rise, T(max): T(max)=TJ(max)-TA(max) where TJ(max) maximum allowable junction temperature (125°C), TA(max) maximum ambient temperature, which will encountered application. Using calculated values T(max) maximum allowable value junction ambient thermal resistance (JA) calculated: JA=T(max)/ maximum allowable value found greater than junction ambient thermal resistance package used, heatsink needed since package alone will dissipate enough heat satisfy these requirements.
Ultra Dropout Operation
AQ8211 allows ultra dropout operation connecting ENABLE >0.95V Vout. This results dropout load current, between VOUT. This feature important when supply voltage dropping near output regulated voltage. Furthermore voltage dropout low, internal power dissipation also reduced thermal requirements device less stringent. www.acutechnology.com Rev. January 2006
Acutechnology Semiconductor Inc.
AQ8211
Package Dimensions
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Acutechnology Semiconductor Inc.
AQ8211
Contact Information
Acutechnology Semiconductor Inc. 3487 McKee Suite Jose 95127
Disclaimer
information furnished Acutechnology this data sheet believed accurate reliable. However, Acutechnology assumes responsibility use. Acutechnology reserves right change circuitry specifications time without notification customer.
TEL: FAX: website:
(408) 259-2300 (408) 259-9160 www.acutechnology.com
Life Support Policy
Acutechnology Products designed authorized components life support devices systems where malfunction product reasonably expected result personal injury. Life support devices systems devices systems that intended surgical implant into body support sustain life, whose failure perform reasonably expected result significant injury user.
AcuRef trademark Acutechnology Semiconductor
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January 2006

Ultra-Low Dropout 500mA Voltage Regulator with Enable Product Spe

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