DESCRIPTIO Optimized Fast Transient Response Output Current: Drop
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LT1764 Series Fast Transient Response, Noise, Regulators
DESCRIPTIO
Optimized Fast Transient Response Output Current: Dropout Voltage: 340mV Noise: 40µVRMS (10Hz 100kHz) Quiescent Current Wide Input Voltage Range: 2.7V Protection Diodes Needed Controlled Quiescent Current Dropout Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3.3V Adjustable Output from 1.21V Quiescent Current Shutdown Stable with 10µF Output Capacitor Stable with Ceramic Capacitors Reverse Battery Protection Reverse Current Thermal Limiting
APPLICATIO
3.3V 2.5V Logic Power Supply Post Regulator Switching Supplies
®1764 dropout regulator optimized fast transient response. device capable supplying output current with dropout voltage 340mV. Operating quiescent current 1mA, dropping shutdown. Quiescent current well controlled; does rise dropout does with many other regulators. addition fast transient response, LT1764 very output voltage noise which makes device ideal sensitive supply applications. Output voltage range from 1.21V 20V. LT1764 regulators stable with output capacitors 10µF. Small ceramic capacitors used without necessary addition common with other regulators. Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting reverse current protection. device available fixed output voltages 1.5V, 1.8V, 2.5V, 3.3V adjustable device with 1.21V reference voltage. LT1764 regulators available 5-lead TO-220 packages.
registered trademarks Linear Technology Corporation.
TYPICAL APPLICATIO
3.3VIN 2.5VOUT Regulator
DROPOUT VOLTAGE (mV)
2.5V 10µF LT1764-2.5 SHDN SENSE
1764 TA01
LOAD CURRENT
1764 TA02
10µF
Dropout Voltage
LT1764 Series
ABSOLUTE MAXIMUM RATINGS (Note
Voltage ±20V Voltage ±20V Input Output Differential Voltage (Note ±20V SENSE Voltage ±20V Voltage SHDN Voltage ±20V Output Short-Circuit Duration Indefinite Operating Junction Temperature Range 40°C 125°C Storage Temperature Range 65°C 150°C Lead Temperature (Soldering, sec). 300°C
PACKAGE/ORDER INFORMATION
FRONT VIEW PACKAGE 5-LEAD PLASTIC SENSE/ADJ* SHDN
ORDER PART NUMBER LT1764EQ LT1764EQ-1.5 LT1764EQ-1.8 LT1764EQ-2.5 LT1764EQ-3.3
*PIN SENSE LT1764-1.8/ LT1764-2.5/LT1764-3.3 LT1764 TJMAX 150°C, 30°C/
Consult factory Industrial Military grade parts.
ELECTRICAL CHARACTERISTICS
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. (Note
PARAMETER Minimum Input Voltage (Notes CONDITIONS ILOAD 0.5A ILOAD 1.5A ILOAD 2.7A, 110°C 125°C ILOAD 40°C 110°C LT1764-1.5 2.21V, ILOAD 2.7V 20V, ILOAD 40°C 110°C 2.7V 20V, ILOAD 2.7A, 110°C 125°C LT1764-1.8 2.3V, ILOAD 2.8V 20V, ILOAD 40°C 110°C 2.8V 20V, ILOAD 2.7A, 110°C 125°C LT1764-2.5 ILOAD 3.5V 20V, ILOAD 40°C 110°C 3.5V 20V, ILOAD 2.7A, 110°C 125°C LT1764-3.3 3.8V, ILOAD 4.3V 20V, ILOAD 40°C 110°C 4.3V 20V, ILOAD 2.7A, 110°C 125°C Voltage (Notes LT1764 2.21V, ILOAD 2.7V 20V, ILOAD 40°C 110°C 2.7V 20V, ILOAD 2.7A, 110°C 125°C 1.477 1.447 1.447 1.773 1.737 1.737 2.462 2.412 2.412 3.250 3.183 3.183 1.192 1.168 1.168 1.500 1.500 1.500 1.800 1.800 1.800 2.500 2.500 2.500 3.300 3.300 3.300 1.210 1.210 1.210 UNITS
Regulated Output Voltage (Note
FRONT VIEW PACKAGE 5-LEAD PLASTIC TO-220 SHDN SENSE/ADJ*
ORDER PART NUMBER LT1764ET LT1764ET-1.5 LT1764ET-1.8 LT1764ET-2.5 LT1764ET-3.3
*PIN SENSE LT1764-1.8/ LT1764-2.5/LT1764-3.3 LT1764 TJMAX 150°C, 50°C/
1.523 1.545 1.545 1.827 1.854 1.854 2.538 2.575 2.575 3.350 3.400 3.400 1.228 1.246 1.246
LT1764 Series
ELECTRICAL CHARACTERISTICS
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. (Note
PARAMETER Line Regulation CONDITIONS LT1764-1.5 LT1764-1.8 LT1764-2.5 LT1764-3.3 LT1764 (Note LT1764-1.5 2.21V 20V, ILOAD 2.3V 20V, ILOAD 20V, ILOAD 3.8V 20V, ILOAD 2.21V 20V, ILOAD 2.7V, ILOAD 2.7V, ILOAD 40°C 110°C 2.7V, ILOAD 2.7A, 110°C 125°C 2.8V, ILOAD 2.8V, ILOAD 40°C 110°C 2.8V, ILOAD 2.7A, 110°C 125°C 3.5V, ILOAD 3.5V, ILOAD 40°C 110°C 3.5V, ILOAD 2.7A, 110°C 125°C 4.3V, ILOAD 4.3V, ILOAD 40°C 110°C 4.3V, ILOAD 2.7A, 110°C 125°C
0.05 0.10 0.13 0.18 0.20 0.27 0.33 0.40 0.66 0.45 0.66
UNITS µVRMS
Load Regulation
LT1764-1.8
LT1764-2.5
LT1764-3.3
LT1764 (Note 2.7V, ILOAD 2.7V, ILOAD 40°C 110°C 2.7V, ILOAD 2.7A, 110°C 125°C Dropout Voltage VOUT(NOMINAL) (Notes ILOAD ILOAD ILOAD 100mA ILOAD 100mA ILOAD 500mA ILOAD 500mA ILOAD 1.5A ILOAD 1.5A ILOAD 2.7A, 110°C 125°C ILOAD ILOAD 40°C 110°C Current VOUT(NOMINAL) (Notes ILOAD ILOAD ILOAD 100mA ILOAD 500mA ILOAD 1.5A ILOAD 2.7A, 110°C 125°C ILOAD 40°C 110°C COUT 10µF, ILOAD 10Hz 100kHz (Notes VOUT VOUT VSHDN VSHDN VSHDN VOUT 1.5V (Avg), VRIPPLE 0.5VP-P, fRIPPLE 120Hz, ILOAD 1.5A
0.02 0.07
0.14
0.25
0.34 0.25 0.75 0.01 0.01
Output Voltage Noise Bias Current Shutdown Threshold SHDN Current (Note Quiescent Current Shutdown Ripple Rejection
LT1764 Series
ELECTRICAL CHARACTERISTICS
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. (Note
PARAMETER Current Limit CONDITIONS VOUT LT1764-1.8, LT1764-2.5, LT1764-3.3 VOUT(NOMINAL) VOUT 0.1V, 40°C 110°C VOUT(NOMINAL) VOUT 0.1V, 110°C 125°C LT1764, LT1764-1.5 2.7V, VOUT 0.1V, 40°C 110°C 2.7V, VOUT 0.1V, 110°C 125°C Input Reverse Leakage Current 20V, VOUT
UNITS
1200 1200 1200 1200
Reverse Output Current (Note LT1764-1.5 VOUT 1.5V, 1.5V LT1764-1.8 VOUT 1.8V, 1.8V LT1764-2.5 VOUT 2.5V, 2.5V LT1764-3.3 VOUT 3.3V, 3.3V LT1764 (Note VOUT 1.21V, 1.21V Note Absolute Maximum Ratings those values beyond which life device impaired. Note LT1764 regulators tested specified under pulse load conditions such that LT1764 100% tested 25°C. Performance 40°C 125°C assured design, characterization correlation with statistical process controls. Note LT1764 (adjustable version) tested specified these conditions with connected pin. Note Operating conditions limited maximum junction temperature. regulated output voltage specification will apply possible combinations input voltage output current. When operating maximum input voltage, output current range must limited. When operating maximum output current, input voltage range must limited. Note satisfy requirements minimum input voltage, LT1764 (adjustable version) tested specified these conditions with external resistor divider (two 4.12k resistors) output voltage 2.42V. external resistor divider will 300µA load output.
Note Dropout voltage minimum input output voltage differential needed maintain regulation specified output current. dropout, output voltage will equal VDROPOUT. Note current tested with VOUT(NOMINAL) 2.7V (whichever greater) current source load. current will decrease higher input voltages. Note bias current flows into pin. Note SHDN current flows into SHDN pin. Note Reverse output current tested with grounded forced rated output voltage. This current flows into pin. Note LT1764, LT1764-1.5 LT1764-1.8 dropout voltage will limited minimum input voltage specification under some output voltage/load conditions. Note combinations absolute maximum input voltage absolute maximum output voltage cannot achieved. absolute maximum differential from input output ±20V. example, with 20V, VOUT cannot pulled below ground.
TYPICAL PERFOR CHARACTERISTICS
Typical Dropout Voltage
GUARANTEED DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV) 125°C 25°C
125°C 25°C
DROPOUT VOLTAGE (mV)
OUTPUT CURRENT
1764
Guaranteed Dropout Voltage
TEST POINTS
Dropout Voltage
1.5A 0.5A 100mA
OUTPUT CURRENT
1764
TEMPERATURE (°C)
1764
LT1764 Series TYPICAL PERFOR CHARACTERISTICS
Quiescent Current
QUIESCENT CURRENT (mA)
LT1764-1.8/2.5/3.3
LT1764
OUTPUT VOLTAGE
OUTPUT VOLTAGE
VSHDN TEMPERATURE (°C)
LT1764-3.3 Output Voltage
3.38 3.36 1.230 1.225
QUIESCENT CURRENT (mA)
OUTPUT VOLTAGE
VOLTAGE
3.34 3.32 3.30 3.28 3.26 3.24 3.22 TEMPERATURE (°C)
LT1764-2.5 Quiescent Current
25°C VSHDN
QUIESCENT CURRENT (mA)
QUIESCENT CURRENT (mA)
INPUT VOLTAGE
INPUT VOLTAGE
QUIESCENT CURRENT (mA)
1764 1756 1764
LT1764-1.8 Output Voltage
1.84 1.83 1.82 1.81 1.80 1.79 1.78 1.77 1.76 TEMPERATURE (°C) 2.58 2.56 2.54 2.52 2.50 2.48 2.46 2.44
LT1764-2.5 Output Voltage
2.42
TEMPERATURE (°C)
1756
1756
LT1764 Voltage
LT1764-1.8 Quiescent Current
25°C VSHDN
1.220 1.215 1.210 1.205 1.200 1.195 1.190 TEMPERATURE (°C)
INPUT VOLTAGE
1756
1764
LT1764-3.3 Quiescent Current
25°C VSHDN
LT1764 Quiescent Current
25°C 4.3k VSHDN
INPUT VOLTAGE
1764
1764
LT1764 Series TYPICAL PERFOR CHARACTERISTICS
LT1764-1.8 Current
20.0 17.5
CURRENT (mA)
25°C VSHDN *FOR VOUT 1.8V
CURRENT (mA)
12.5 10.0
500mA*
300mA*
500mA*
CURRENT (mA)
15.0
100mA* INPUT VOLTAGE
LT1764 Current
25°C VSHDN *FOR VOUT 1.21V
CURRENT (mA)
CURRENT (mA)
2.42 500mA* 4.33 300mA* 12.1 100mA*
CURRENT (mA)
INPUT VOLTAGE
LT1764-3.3 Current
25°C VSHDN *FOR VOUT 3.3V
CURRENT (mA)
CURRENT (mA)
CURRENT (mA)
1.5A* 4.71 0.7A*
INPUT VOLTAGE
1764
LT1764-2.5 Current
25°C VSHDN *FOR VOUT 2.5V
LT1764-3.3 Current
500mA* 300mA* 100mA* 25°C VSHDN *FOR VOUT 3.3V
100mA*
8.33 300mA*
INPUT VOLTAGE
INPUT VOLTAGE
1764
1764
LT1764-1.8 Current
25°C VSHDN *FOR VOUT 1.8V
LT1764-2.5 Current
25°C VSHDN *FOR VOUT 2.5V 0.83
1.5A*
1.66 1.5A* 3.57 0.7A*
2.57 0.7A*
INPUT VOLTAGE
INPUT VOLTAGE
1764
1764
1764
LT1764 Current
25°C VSHDN *FOR VOUT 1.21V 0.81 1.5A*
Current ILOAD
VOUT(NOM)
1.73 0.7A*
INPUT VOLTAGE
OUTPUT CURRENT
1764
1764
1764
LT1764 Series TYPICAL PERFOR CHARACTERISTICS
SHDN Threshold (On-to-Off)
SHDN THRESHOLD
TEMPERATURE (°C)
SHDN THRESHOLD
SHDN INPUT CURRENT (µA)
SHDN Input Current
VSHDN
SHDN INPUT CURRENT (µA)
BIAS CURRENT (µA)
TEMPERATURE (°C)
CURRENT LIMIT
Current Limit
VOUT TEMPERATURE (°C)
REVERSE OUTPUT CURRENT (mA)
LT1764 LT1764-1.8 LT1764-2.5 LT1764-3.3 25°C CURRENT FLOWS INTO OUTPUT VOUT VADJ (LT1764) VOUT (LT1764-1.8/-2.5/-3.3) OUTPUT VOLTAGE
REVERSE OUTPUT CURRENT (mA)
CURRENT LIMIT
1764 1764 1764
SHDN Threshold (Off-to-On)
TEMPERATURE (°C)
SHDN Input Current
SHDN VOLTAGE
1764
1764
Bias Current
Current Limit
-50°C 125°C 25°C
TEMPERATURE (°C)
INPUT/OUTPUT DIFFERENTIAL
1764
1756
Reverse Output Current
Reverse Output Current
VOUT 1.21V (LT1764) 1.8V (LT1764-1.8) VOUT 2.5V (LT1764-2.5) VOUT 3.3V (LT1764-3.3) TEMPERATURE (°C) LT1764 LT1764-1.8/-2.5/-3.3
1764
1764
LT1764 Series TYPICAL PERFOR CHARACTERISTICS
Ripple Rejection
RIPPLE REJECTION (dB)
RIPPLE REJECTION (dB)
MINIMUM INPUT VOLTAGE
COUT 10µF 1.5A TANTALUM VOUT(NOM) 50mVRMS RIPPLE 100k FREQUENCY (Hz) COUT 100µF TANTALUM CERAMIC
Load Regulation
OUTPUT NOISE SPECTRAL DENSITY (µV/Hz)
LOAD REGULATION (mV)
OUTPUT NOISE (µVRMS)
LT1764
LT1764-1.8 LT1764-2.5 LT1764-3.3 2.7V (LT1764) VOUT(NOM) (LT1764-1.8/-2.5/-3.3) TEMPERATURE (°C)
LT1764-3.3 10Hz 100kHz Output Noise
OUTPUT VOLTAGE DEVIATION
-0.1 -0.2 1.00 0.75 0.50 0.25 TIME (µs)
1764
OUTPUT VOLTAGE DEVIATION
VOUT 100µV/DIV
LOAD CURRENT
LOAD CURRENT
COUT 10µF
1ms/DIV
1764 1764
Ripple Rejection
1.5A VOUT(NOM) 0.5VP-P RIPPLE 120Hz
LT1764 Minimum Input Voltage
1.5A
500mA 100mA
TEMPERATURE (°C)
TEMPERATURE (°C)
1764
1764
Output Noise Spectral Density
COUT 10µF ILOAD
Output Noise Load Current (10Hz 100kHz)
LT1764-1.8 LT1764 LT1764-2.5 COUT 10µF LT1764-3.3
LT1764-3.3
LT1764-2.5
LT1764
LT1764-1.8
0.01
FREQUENCY (Hz)
100k
1764
0.0001
0.001
0.01 LOAD CURRENT
1764
LT1764-3.3 Transient Response
LT1764-3.3 Transient Response
-0.1 -0.2 4.3V 33µF COUT 100µF TANTALUM CERAMIC
4.3V 3.3µF TANTALUM COUT 10µF TANTALUM
TIME (µs)
1764
1764
LT1764 Series
CTIO
SHDN (Pin Shutdown. SHDN used LT1764 regulators into power shutdown state. output will when SHDN pulled low. SHDN driven either logic opencollector logic with pull-up resistor. pull-up resistor required supply pull-up current opencollector gate, normally several microamperes, SHDN current, typically 7µA. unused, SHDN must connected VIN. device will power shutdown state SHDN connected. (Pin Input. Power supplied device through pin. bypass capacitor required this device more than inches away from main input filter capacitor. general, output impedance battery rises with frequency, advisable include bypass capacitor battery-powered circuits. bypass capacitor range 10µF sufficient. LT1764 regulators designed withstand reverse voltages with respect ground pin. case reverse input, which happen battery plugged backwards, device will there diode series with input. There will reverse current flow into regulator reverse voltage will appear load. device will protect both itself load. (Pin Ground. (Pin Output. output supplies power load. minimum output capacitor 10µF required prevent oscillations. Larger output capacitors will required applications with large transient loads limit peak voltage transients. Applications Information section more information output capacitance reverse output characteristics. SENSE (Pin Sense. fixed voltage versions LT1764 SENSE input error amplifier. Optimum regulation will obtained point where SENSE connected regulator. critical applications, small voltage drops caused resistance (RP) traces between regulator load. These eliminated connecting SENSE output load shown Figure (Kelvin Sense Connection). Note that voltage drop across external traces will dropout voltage regulator. SENSE bias current 600µA nominal rated output voltage. SENSE pulled below ground dual supply system where regulator load returned negative supply) still allow device start operate. (Pin Adjust. adjustable LT1764, this input error amplifier. This internally clamped ±7V. bias current which flows into pin. voltage 1.21V referenced ground output voltage range 1.21V 20V.
LT1764
SHDN
SENSE
LOAD
1764
Figure Kelvin Sense Connection
LT1764 Series
APPLICATIO ATIO
LT1764 series dropout regulators optimized fast transient response. devices capable supplying dropout voltage 340mV. operating quiescent current (1mA) drops less than shutdown. addition quiescent current, LT1764 regulators incorporate several protection features which make them ideal battery-powered systems. devices protected against both reverse input reverse output voltages. battery backup applications where output held backup battery when input pulled ground, LT1764-X acts like diode series with output prevents reverse current flow. Additionally, dual supply applications where regulator load returned negative supply, output pulled below ground much still allow device start operate. Adjustable Operation adjustable version LT1764 output voltage range 1.21V 20V. output voltage ratio external resistors shown Figure device servos output maintain voltage 1.21V referenced ground. current then equal 1.21V/R1 current current plus bias current. bias current, 25°C, flows through into pin. output voltage calculated using formula Figure value should less than 4.17k minimize errors output voltage caused bias current. Note that shutdown output turned divider current will zero.
LT1764
1764
VOUT
CHANGE VALUE
VOUT 1.21V (IADJ )(R2) VADJ 1.21V IADJ 25°C OUTPUT RANGE 1.21V
Figure Adjustable Operation
adjustable device tested specified with tied output voltage 1.21V. Specifications output voltages greater than 1.21V will proportional ratio desired output voltage 1.21V: VOUT/1.21V. example, load regulation output current change typical VOUT 1.21V. VOUT load regulation (5V/1.21V)(-3mV) 12.4mV Output Capacitance Transient Response LT1764 regulators designed stable with wide range output capacitors. output capacitor affects stability, most notably with small capacitors. minimum output capacitor 10µF with less recommended prevent oscillations. Larger values output capacitance decrease peak deviations provide improved transient response larger load current changes. Bypass capacitors, used decouple individual components powered LT1764-X, will increase effective output capacitor value. Extra consideration must given ceramic capacitors. Ceramic capacitors manufactured with variety dielectrics, each with different behavior over temperature applied voltage. most common dielectrics used Z5U, Y5V, X7R. dielectrics good providing high capacitances small package, exhibit strong voltage temperature coefficients shown Figures When used with regulator, 10µF capacitor exhibit
-100 BOTH CAPACITORS 16V, 1210 CASE SIZE, 10µF BIAS VOLTAGE
1764
Figure Ceramic Capacitor Bias Characteristics
LT1764 Series
APPLICATIO ATIO
CHANGE VALUE
BOTH CAPACITORS 16V, 1210 CASE SIZE, 10µF TEMPERATURE (°C)
-100
1764
Figure Ceramic Capacitor Temperature Characteristics
effective value over operating temperature range. dielectrics result more stable characteristics more suitable output capacitor. type better stability across temperature, while less expensive available higher values. Voltage temperature coefficients only sources problems. Some ceramic capacitors have piezoelectric response. piezoelectric device generates voltage across terminals mechanical stress, similar piezoelectric accelerometer microphone works. ceramic capacitor stress induced vibrations system thermal transients. Overload Recovery Like many power regulators, LT1764-X safe operating area protection. safe area protection decreases current limit input-to-output voltage increases keeps power transistor inside safe operating region values input-to-output voltage. protection designed provide some output current values input-to-output voltage device breakdown.
When power first turned input voltage rises, output follows input, allowing regulator start into very heavy loads. During start-up, input voltage rising, input-to-output voltage differential small, allowing regulator supply large output currents. With high input voltage, problem occur wherein removal output short will allow output voltage recover. Other regulators, such LT1085, also exhibit this phenomenon, unique LT1764 series. problem occurs with heavy output load when input voltage high output voltage low. Common situations immediately after removal short circuit when SHDN pulled high after input voltage already been turned load line such load intersect output current curve points. this happens, there stable output operating points regulator. With this double intersection, input power supply need cycled down zero brought again make output recover. Output Voltage Noise LT1764 regulators have been designed provide output voltage noise over 10Hz 100kHz bandwidth while operating full load. Output voltage noise typically 50nVHz over this frequency bandwidth LT1764 (adjustable version). higher output voltages (generated using resistor divider), output voltage noise will gained accordingly. This results noise over 10Hz 100kHz bandwidth 15µVRMS LT1764 increasing 37µVRMS LT1764-3.3. Higher values output voltage noise measured when care exercised with regards circuit layout testing. Crosstalk from nearby traces induce unwanted noise onto output LT1764-X. Power supply ripple rejection must also considered; LT1764 regulators have unlimited power supply rejection will pass small portion input noise through output.
LT1764 Series
APPLICATIONS INFORMATION
Thermal Considerations power handling capability device limited maximum rated junction temperature (125°C). power dissipated device made components: Output current multiplied input/output voltage differential: (IOUT)(VIN VOUT), current multiplied input voltage: (IGND)(VIN). current found using Current curves Typical Performance Characteristics. Power dissipation will equal components listed above. LT1764 series regulators have internal thermal limiting designed protect device during overload conditions. continuous normal conditions, maximum junction temperature rating 125°C must exceeded. important give careful consideration sources thermal resistance from junction ambient. Additional heat sources mounted nearby must also considered. surface mount devices, heat sinking accomplished using heat spreading capabilities board copper traces. Surface mount heatsinks plated through-holes also used spread heat generated power devices. following table lists thermal resistance several different board sizes copper areas. measurements were taken still 1/16" FR-4 board with ounce copper.
Table Package, 5-Lead
COPPER AREA TOPSIDE* 2500mm2 1000mm2 125mm
BACKSIDE 2500mm2 2500mm2 2500mm
BOARD AREA 2500mm2 2500mm2 2500mm
THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 23°C/W 25°C/W 33°C/W
*Device mounted topside.
Package, 5-Lead TO-220 Thermal Resistance (Junction-to-Case) 2.5°C/W
Calculating Junction Temperature Example: Given output voltage 3.3V, input voltage range output current range 500mA maximum ambient temperature 50°C, what will maximum junction temperature power dissipated device will equal IOUT(MAX)(VIN(MAX) VOUT) IGND(VIN(MAX)) where, IOUT(MAX) 500mA VIN(MAX) IGND (IOUT 500mA, 10mA 500mA(6V 3.3V) 10mA(6V) 1.41W Using package, thermal resistance will range 23°C/W 33°C/W depending copper area. junction temperature rise above ambient will approximately equal 1.41W(28°C/W) 39.5°C maximum junction temperature will then equal maximum junction temperature rise above ambient plus maximum ambient temperature TJMAX 50°C 39.5°C 89.5°C Protection Features LT1764 regulators incorporate several protection features which make them ideal battery-powered circuits. addition normal protection features associated with monolithic regulators, such current limiting thermal limiting, devices protected against reverse input voltages, reverse output voltages reverse voltages from output input. Current limit protection thermal overload protection intended protect device against current overload conditions output device. normal operation, junction temperature should exceed 125°C. input device will withstand reverse voltages 20V. Current flow into device will limited less than negative voltage will appear output.
LT1764 Series
APPLICATIONS INFORMATION
device will protect both itself load. This provides protection against batteries which plugged backward. output LT1764-X pulled below ground without damaging device. input left open circuit grounded, output pulled below ground 20V. fixed voltage versions, output will like large resistor, typically higher, limiting current flow typically less than 600µA. adjustable versions, output will like open circuit; current will flow pin. input powered voltage source, output will source short-circuit current device will protect itself thermal limiting. this case, grounding SHDN will turn device stop output from sourcing short-circuit current. adjustable device pulled above below ground much without damaging device. input left open circuit grounded, will like open circuit when pulled below ground like large resistor (typically series with diode when pulled above ground. situations where connected resistor divider that would pull above clamp voltage output pulled high, input current must limited less than 5mA. example, resistor divider used provide regulated 1.5V output from 1.21V reference when output forced 20V. resistor resistor divider must chosen limit current into less than when difference between pins divided maximum current into yields minimum resistor value 2.6k. circuits where backup battery required, several different input/output conditions occur. output voltage held while input either pulled ground, pulled some intermediate voltage, left open circuit. Current flow back into output will follow curve shown Figure When LT1764-X forced below pulled above pin, input current will typically drop less than 2µA. This happen input device connected discharged (low voltage) battery output held either backup battery second regulator circuit. state SHDN will have effect reverse output current when output pulled above input.
REVERSE OUTPUT CURRENT (mA)
1764
LT1764
LT1764-1.8
25°C CURRENT FLOWS INTO OUTPUT VOUT VADJ (LT1764) VOUT (LT1764-1.8, LT1764-2.5, LT1764-3.3) LT1764-2.5
LT1764-3.3
OUTPUT VOLTAGE
Figure Reverse Output Current
LT1764 Series
TYPICAL APPLICATIO
Preregulator Provides Efficiency Over Line Variations
500µH 1N4148 115VIN 12.1k* NTE5437 1N4002 "SYNC" 1N4002 POINTS 2.4k 1N4002
115VIN
140V
22µF
COILTRONICS CTX500-2-52 STANCOR P-8560 FILM RESISTOR
2.7V
10µF
3.3µF
NTE5437
LT1764-3.3
10000µF 34k*
SHDN
22µF
VOUT 3.3V
LT1018
1N4148
200k 0.1µF
0.033µF
LT1018 1N4148
LT1006
LT1004 1.2V
1764 TA03
Adjustable Current Source
0.01 2.2k 2.2k LT1764-1.8 SHDN 100k
LT1004-1.2
LOAD
40.2k
ADJUST CONSTANT CURRENT
LT1366
1764 TA04
LT1764 Series
PACKAGE DESCRIPTION
0.256 (6.502)
0.060 (1.524)
0.060 (1.524)
0.183 (4.648)
0.075 (1.905) 0.300 (7.620) BOTTOM VIEW HATCHED AREA SOLDER PLATED COPPER HEAT SINK +0.012 0.143 -0.020 0.067 (1.70) 0.028 0.038 (0.711 0.965) 0.013 0.023 (0.330 0.584)
0.390 0.415 (9.906 10.541)
0.230 0.270 (5.842 6.858) 0.460 0.500 (11.684 12.700) 0.570 0.620 (14.478 15.748) 0.330 0.370 (8.382 9.398) 0.700 0.728 (17.78 18.491) 0.620 (15.75)
0.067 (1.70)
0.028 0.038 (0.711 0.965)
Information furnished Linear Technology Corporation believed accurate reliable. However, responsibility assumed use. Linear Technology Corporation makes representation that interconnection circuits described herein will infringe existing patent rights.
Dimensions inches (millimeters) unless otherwise noted.
Package 5-Lead Plastic
(LTC 05-08-1461)
0.060 (1.524)
0.390 0.415 (9.906 10.541)
0.165 0.180 (4.191 4.572)
0.045 0.055 (1.143 1.397) +0.008 0.004 -0.004
0.330 0.370 (8.382 9.398)
0.059 (1.499)
+0.203 0.102 -0.102
0.095 0.115 (2.413 2.921) 0.050 0.012 (1.270 0.305)
Q(DD5) 1098
+0.305 3.632 -0.508
Package 5-Lead Plastic TO-220 (Standard)
(LTC 05-08-1421)
0.147 0.155 (3.734 3.937)
0.165 0.180 (4.191 4.572)
0.045 0.055 (1.143 1.397)
SEATING PLANE 0.152 0.202 0.260 0.320 (3.861 5.131) (6.60 8.13)
0.095 0.115 (2.413 2.921) 0.155 0.195* (3.937 4.953) 0.013 0.023 (0.330 0.584)
0.135 0.165 (3.429 4.191)
MEASURED SEATING PLANE
(TO-220) 0399
LT1764 Series
TYPICAL APPLICATIO
Paralleling Regulators Higher Output Current
0.01
3.7V
100µF
LT1764-3.3 SHDN 0.01 LT1764
3.3V 22µF
6.65k 4.12k
SHDN
SHDN
2.2k
2.2k
0.01µF
LT1366
1764 TA05
RELATED PARTS
PART NUMBER LT1120 LT1121 LT1129 LT1175 LT1374 LT1521 LT1529 LT1573 LT1575 LT1735 LT1761 Series LT1762 Series LT1763 Series LT1962 LT1963 DESCRIPTION 125mA Dropout Regulator with 20µA 150mA Micropower Dropout Regulator 700mA Micropower Dropout Regulator 500mA Negative Dropout Micropower Regulator 4.5A, 500kHz Step-Down Converter 300mA Dropout Micropower Regulator with Shutdown Dropout Regulator with 50µA UltraFastTransient Response Dropout Regulator UltraFast Transient Response Dropout Regulator Synchronous Step-Down Converter 100mA, Noise, Dropout Micropower Regulators SOT-23 150mA, Noise, Micropower Regulators 500mA, Noise, Micropower Regulators 300mA, Noise, Micropower Regulator 1.5A, Noise, Fast Transient Response COMMENTS Includes 2.5V Reference Comparator 30µA SOT-223 Package 50µA Quiescent Current 45µA 0.26V Dropout Voltage, SOT-223 Package 4.5A, 0.07 Internal Switch, SO-8 Package 15µA Reverse Battery Protection 500mV Dropout Voltage Drives External Drives External N-Channel MOSFET High Efficiency, OPTI-LOOPCompensation 20µA Quiescent Current, 20µVRMS Noise, SOT-23 Package 25µA Quiescent Current, 20µVRMS Noise, MSOP Package 30µA Quiescent Current, 20µVRMS Noise, SO-8 Package 20µVRMS Noise, MSOP Package 40µVRMS Noise, SOT-223 Package
UltraFast OPTI-LOOP trademarks Linear Technology Corporation.
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, 95035-7417
(408)432-1900 FAX: (408) 434-0507 www.linear-tech.com
1764fs sn1764 LT/TP 0700 PRINTED
LINEAR TECHNOLOGY CORPORATION 2000
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