Dropout Voltage Regulator with Enable Function Product Specificat

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Dropout Voltage Regulator with Enable Function Product Specificat

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AQ1541
Dropout Voltage Regulator with Enable Function
Product Specification Revision September 2006
AQ1541 dropout three terminal voltage regulator, offered popular fixed options adjustable version that precise voltage from 1.22V with external resistors. drops into footprint popular LM1117 SOT-223 provides true fourth separated from output tab. extra allows enable function that provides remote turn-off power consumption. draws virtually zero current shutdown mode. Enable implements Sequential, Ratiometric, Simultaneous sequencing schemes. assure accuracy within 1.5% over temperature heart AQ1541 selfcorrecting AcuRefbandgap reference. On-chip current limit thermal shutdown with hysteresis protects against combination overload ambient temperature that might cause junction temperature exceed safe limits. AQ1541 featured SOT223 4-lead TetraPackpackage.
Applications Graphic cards motherboards Switching power supply post-regulation Telecom equipment video player Features Enable implements sequencing
SOT223-3 footprint Vout tolerance 1.5% over temperature Eliminates expensive components Stable with cost capacitor dropout voltage Amp) Thermal protection with hysteresis Short circuit protection Offered with 1.8V, 2.5V, 3.3V fixed adjustable output RoHS compliant available
Typical Application
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AQ1541
Acutechnology Semiconductor Inc.
AQ1541
Configuration
Descriptions
Name VOUT Ground/Adjust ENABLE Function Accepts Regulated Output fixed option Adjust adjustable option Active high, ENABLE (0.5V VOUT). Connect when use.
Functional Block Diagram
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September 2005
Acutechnology Semiconductor Inc.
AQ1541
Ordering Information
Device AQ1541 AQ1541 AQ1541 AQ1541 AQ1541 AQ1541 AQ1541 AQ1541
Note:
Operating 125C° 125C° 125C° 125C° 125C° 125C° 125C° 125C°
%Tol
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
Wrap
Ordering Number AQ1541CY-S4-18-TR AQ1541CY-S4-18-TRL AQ1541CY-S4-25-TR AQ1541CY-S4-25-TRL AQ1541CY-S4-33-TR AQ1541CY-S4-33-TRL AQ1541CY-S4-AJ-TR AQ1541CY-S4-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 Maximum Power Dissipation (Internally limited) Maximum Junction Temperature Operating Junction Temperature Range Storage Temperature Range Lead Temperature (Soldering, sec.) packages Lead Temperature (Soldering, 4sec.) SOT- package Value Units Volts Volts
Thermal Management
Thermal Resistance (Junction TAB) SOT-223 Thermal Resistance (Junction Ambient) SOT-223 (tab soldered copper PCB) www.acutechnology.com Typical Value Typical Value Rev. Units °C/W Units °C/W September 2005
Acutechnology Semiconductor Inc.
AQ1541
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 125°C VOUT (1.5V 10V) IOUT (10mA Amp) IOUT Drop Voltage IOUT IOUT IQON Current Limit Quiescent Current VIN-VOUT VENABLE 125°C VENABLE 125°C With respect With respect VOUT
ENABLE ENABLE
VOUT VOUT 0.035 0.91 0.93 0.95
+1.5 0.95 0.95
Units
-1.5
IQOFF VADJ IADJ IADJ IQMIN PSRR TSDHYST
Quiescent Current Enable Voltage (OFF) Enable Voltage (ON) Enable Current (OFF) Enable Current (ON) Reference Voltage Adjust Current Adjust Current Change Minimum Load Current Temperature Coefficient Temperature Stability Output Noise Ripple Rejection Ratio Thermal Shutdown Hysteresis
0.25
0.45 1.232 1.238 0.005 0.003
%/°C %/°C VOUT
1.208 1.202
Adjustable version only 125°C Adjustable version only 10mA IOUT 1Amp Maintain regulation
1.220
Junction Temperature
Notes: duty cycle pulse testing with Kelvin connections required. Measure (VIN VOUT) when VOUT, VREF Bandwidth 10Hz 10kHz 120Hz input ripple Adjustable version only www.acutechnology.com Rev. September 2005
Acutechnology Semiconductor Inc.
AQ1541
Typical Response Curves
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Rev.
September 2005
Acutechnology Semiconductor Inc.
AQ1541
Application Notes
Typical Application
Notes: Output voltage 1.22V +R1)/R1 Input output capacitors should located close device. AQ1541 will remain stable with 1.0µF. Overall transient performance improved with increased capacitance. output fully enabled when above expected output. should pulled substantially above Vin. driven either digital analog signal control either turn-on time give full control risetime.
Stability
input capacitor recommended. 1.0µF capacitor input suitable input bypassing almost applications. larger capacitor also suitable. adjustable version "adjust" terminal bypassed ground with bypass capacitor (CADJ) improve ripple rejection. This bypass capacitor prevents ripple from being amplified output voltage increased. ripple frequency, impedance CADJ should less than (being resistor between output adjust pin) prevent ripple from being amplified: 1/(2*fRIPPLE* CADJ) normally range output capacitor critical maintaining regular stability. AQ1541 stable with output capacitor greater than 1uF. course increase output capacitor will merely improve loop stability load transient response. case adjustable regulator, when CADJ used, larger output capacitance required. Tantalum Capacitors exhibit best stability over wide range loads recommended.
Output Voltage
AQ1541 adjustable version develops 1.22V reference voltage between output adjust terminal. This voltage applied across resistor generate constant www.acutechnology.com Rev. September 2005
Acutechnology Semiconductor Inc.
AQ1541
current (I1). current from adjust terminal could introduce error output, since very small 20µA) compared with current very constant with line load changes, error ignored. constant current then flows through resistor sets output voltage desired level. fixed voltages resistor integrated inside devices. AQ1541 regulates voltage that appears between output ground pins between output adjust 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. When adjustable regulator used, best performance obtained with positive side resistor tied directly output terminal regulator rather than near load. This will eliminate line drops from appearing effectively series with reference degrading regulation. addition ground side resistor returned near ground load provide remote ground sensing improve load regulation. capacitor (470pF) between system ground will enhance stability.
Enable/Sequencing
AQ1541 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 www.acutechnology.com Rev. September 2005
Acutechnology Semiconductor Inc.
AQ1541
shutdown. this end, AQ1541 allows analog control output voltage ENBL pin. This allows sequential, ratio-metric simultaneous sequencing schemes. simple sequencing scheme, output voltage delayed with respect application connecting network shown figure below. This generates slow ramp enable pin; output follows below this ramp until output reaches regulation. Virtually current flows into enable until reaches enable voltage which equal Vout Therefore, time delay reliably using time constant known slow enable pin.
FIG.3 Enable delay circuit Enable Output raise with respect shown Fig.3 below. Vout 2.5V, output regulating after input supply applied.
FIG. Enable circuit delays output www.acutechnology.com Rev. September 2005
Acutechnology Semiconductor Inc.
AQ1541
Protection Diodes
Unlike older regulators, AQ1541 family does need protection diodes between adjustment output from output input prevent over-stressing die. Internal resistors limiting internal current paths adjustment pin. Therefore, even with capacitors adjustment pin, protection diode needed ensure device safety under short circuit conditions. External diodes between input output 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. AQ1541 regulators have internal thermal shutdown protect device from overheating. Under possible operating conditions, junction temperature AQ1541 must lower than 125°C. heatsink required depending maximum power dissipation maximum ambient temperature application. determine heatsink needed, power dissipated regulator, must calculated: (VIN-VOUT) where load current. next parameter which must calculated maximum 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.
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Rev.
September 2005
Acutechnology Semiconductor Inc.
AQ1541
Package Dimensions SOT223-4 TetraPack
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.
TetraPack AcuRef trademarks Acutechnology Semiconductor www.acutechnology.com Rev. September 2005

Dropout Voltage Regulator with Enable Function Product Specificat

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