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LT3010/LT3010-5 50mA, 3V to 80V Low Dropout Micropower Linear Regulator
FEATURES
s s s s s s s s s s s
DESCRIPTIO
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Wide Input Voltage Range: 3V to 80V Low Quiescent Current: 30A Low Dropout Voltage: 300mV Output Current: 50mA Thermally Enhanced 8-Lead MSOP Package No Protection Diodes Needed Fixed Output Voltage: 5V (LT3010-5) Adjustable Output from 1.275V to 60V (LT3010) 1A Quiescent Current in Shutdown Stable with 1F Output Capacitor Stable with Aluminum, Tantalum or Ceramic Capacitors Reverse-Battery Protection No Reverse Current Flow from Output Thermal Limiting
The LT(R)3010 is a high voltage, micropower low dropout linear regulator. The device is capable of supplying 50mA output current with a dropout voltage of 300mV. Designed for use in battery-powered or high voltage systems, the low quiescent current (30A operating and 1A in shutdown) makes the LT3010 an ideal choice. Quiescent current is also well controlled in dropout. Other features of the LT3010 include the ability to operate with very small output capacitors. The regulators are stable with only 1F on the output while most older devices require between 10F and 100F for stability. Small ceramic capacitors can be used without the necessary addition of ESR as is common with other regulators. Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting and reverse current protection. The device is available in a fixed output voltage of 5V and as an adjustable device with a 1.275V reference voltage. The LT3010 regulator is available in the 8-lead MSOP package with an exposed pad for enhanced thermal handling capability.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Low Current High Voltage Regulators Regulator for Battery-Powered Systems Telecom Applications Automotive Applications
TYPICAL APPLICATIO
350
5V Supply with Shutdown
IN VIN 5.4V TO 80V 1F SHDN SENSE GND
3010 TA01
300
OUT LT3010-5
VOUT 5V 50mA 1F
DROPOUT VOLTAGE (mV)
250 200 150 100 50 0 0 10 20 30 40 50
3010 TA02
VSHDN (PIN 5) OUTPUT <0.3V OFF >2.0V ON NC ON
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Dropout Voltage
OUTPUT CURRENT (mA)
3010f
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LT3010/LT3010-5
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW OUT SENSE/ADJ* NC GND 1 2 3 4 8 7 6 5 IN NC NC SHDN
IN Pin Voltage ................................................... 80V OUT Pin Voltage ............................................... 60V IN to OUT Differential Voltage ........................... 80V ADJ Pin Voltage .................................................. 7V SHDN Pin Input Voltage ................................... 80V Output Short-Circuit Duration ..................... Indefinite Storage Temperature Range ............ -65C to 150C Operating Junction Temperature Range (Notes 3, 10, 11) ......................... -40C to 125C Lead Temperature (Soldering, 10 sec)............ 300C
ORDER PART NUMBER LT3010EMS8E LT3010EMS8E-5 MS8 PART MARKING LTZF LTAEF
MS8E PACKAGE 8-LEAD PLASTIC MSOP *SENSE FOR LT3010-5, ADJ FOR LT3010 TJMAX = 125C, JA = 40C/ W, JC = 16C/ W SEE APPLICATIONS INFORMATION SECTION. EXPOSED PAD IS GND (MUST BE SOLDERED TO PCB) MEASURED AT BOTTOM PAD
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25C.
PARAMETER Minimum Input Voltage Regulated Output Voltage (Note 3) ADJ Pin Voltage (Notes 2,3) Line Regulation Load Regulation CONDITIONS LT3010 LT3010-5 LT3010 LT3010-5 LT3010 (Note 2) LT3010-5 LT3010 (Note 2) Dropout Voltage VIN = VOUT(NOMINAL) (Notes 4, 5) ILOAD = 1mA ILOAD = 1mA ILOAD = 10mA ILOAD = 10mA ILOAD = 50mA ILOAD = 50mA GND Pin Current VIN = VOUT(NOMINAL) (Notes 4, 6) Output Voltage Noise ADJ Pin Bias Current Shutdown Threshold SHDN Pin Current (Note 8) Quiescent Current in Shutdown ILOAD = 0mA ILOAD = 1mA ILOAD = 10mA ILOAD = 50mA COUT = 10F, ILOAD = 50mA, BW = 10Hz to 100kHz (Note 7) VOUT = Off to On VOUT = On to Off VSHDN = 0V VSHDN = 6V VIN = 6V, VSHDN = 0V 0.3 ILOAD = 50mA VIN = 5.5V, ILOAD = 1mA 6V < VIN < 80V, 1mA < ILOAD < 50mA VIN = 3V, ILOAD = 1mA 4V < VIN < 80V, 1mA < ILOAD < 50mA VIN = 5.5V to 80V, ILOAD = 1mA VIN = 3V to 80V, ILOAD = 1mA VIN = 6V, ILOAD = 1mA to 50mA VIN = 6V, ILOAD = 1mA to 50mA VIN = 4V, ILOAD = 1mA to 50mA VIN = 4V, ILOAD = 1mA to 50mA
q q q q q q
MIN 4.925 4.850 1.258 1.237
TYP 3 5.000 5.000 1.275 1.275 3 3 25 10
MAX 4 5.075 5.150 1.292 1.313 15 13 50 90 20 32 150 190 260 350 370 550 60 180 700 3.3 100 2 2 0.5 5
UNITS V V V V V mV mV mV mV mV mV mV mV mV mV mV mV A A A mA VRMS nA V V A A A
q
100
q
200
q
300
q q q q q
30 100 400 1.8 100 50 1.3 0.8 0.5 0.1 1
2
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3010f
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LT3010/LT3010-5
ELECTRICAL CHARACTERISTICS
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TJ = 25C.
PARAMETER Ripple Rejection Current Limit CONDITIONS LT3010 LT3010-5 VIN = 7V(Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 50mA VIN = 7V(Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 50mA q q q 10 8 MIN TYP 65 60 60 60 6 20 15 MAX 75 68 140 UNITS dB dB mA mA mA mA A A
VIN = 7V, VOUT = 0V LT3010-5 VIN = 6V, VOUT = -0.1V LT3010 (Note 2) VIN = 4V, VOUT = -0.1V VIN = -80V, VOUT = 0V LT3010-5 LT3010 (Note 2) VOUT = 5V, VIN < 5V VOUT = 1.275V, VIN < 1.275V
Input Reverse Leakage Current Reverse Output Current (Note 9)
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT3010 (adjustable version) is tested and specified for these conditions with the ADJ pin connected to the OUT pin. Note 3: Operating conditions are limited by maximum junction temperature. The regulated output voltage specification will not apply for all possible combinations of input voltage and output current. When operating at maximum input voltage, the output current range must be limited. When operating at maximum output current, the input voltage range must be limited. Note 4: To satisfy requirements for minimum input voltage, the LT3010 (adjustable version) is tested and specified for these conditions with an external resistor divider (249k bottom, 392k top) for an output voltage of 3.3V. The external resistor divider will add a 5A DC load on the output. Note 5: Dropout voltage is the minimum input to output voltage differential needed to maintain regulation at a specified output current. In dropout, the output voltage will be equal to (VIN - VDROPOUT).
Note 6: GND pin current is tested with VIN = VOUT (nominal) and a current source load. This means the device is tested while operating in its dropout region. This is the worst-case GND pin current. The GND pin current will decrease slightly at higher input voltages. Note 7: ADJ pin bias current flows into the ADJ pin. Note 8: SHDN pin current flows out of the SHDN pin. Note 9: Reverse output current is tested with the IN pin grounded and the OUT pin forced to the rated output voltage. This current flows into the OUT pin and out the GND pin. Note 10: The LT3010E is guaranteed to meet performance specifications from 0C to 125C operating junction temperature. Specifications over the -40C to 125C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. Note 11: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability.
TYPICAL PERFOR A CE CHARACTERISTICS
Typical Dropout Voltage
500 450
DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV)
600 500
DROPOUT VOLTAGE (mV)
400 350 300 250 200 150 100 50 0 TJ = 25C TJ = 125C
0
5
10 15 20 25 30 35 40 45 50 OUTPUT CURRENT (mA)
3010 G01
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Guaranteed Dropout Voltage
= TEST POINTS
Dropout Voltage
500 450 400 350 300 250 200 150 100 50 IL = 1mA IL = 10mA IL = 50mA
400 300
TJ 125C TJ 25C
200 100 0 0 5 10 15 20 25 30 35 40 45 50 OUTPUT CURRENT (mA)
3010 G02
0 -50 -25
50 25 0 75 TEMPERATURE (C)
100
125
3010 G03
3010f
3
LT3010/LT3010-5 TYPICAL PERFOR A CE CHARACTERISTICS
Quiescent Current
40 35
QUIESCENT CURRENT (A)
ADJ PIN VOLTAGE (V)
25 20 15 10 5 0 - 50 - 25 0 VSHDN = 0V 75 50 25 TEMPERATURE (C) 100 125 VIN > 6V RL = , IL = 0 (LT3010-5) RL = 250k, IL = 5A (LT3010)
1.280 1.275 1.270 1.265 1.260 1.255 - 50 - 25 0 75 50 25 TEMPERATURE (C) 100 125
OUTPUT VOLTAGE (V)
30
VSHDN = VIN
LT3010 Quiescent Current
50 45 TJ = 25C RL = VSHDN = VIN 200
QUIESCENT CURRENT (A)
QUIESCENT CURRENT (A)
40 35 30 25 20 15 10 5 0 0 1 2
GND PIN CURRENT (mA)
VSHDN = 0V 34567 INPUT VOLTAGE (V) 8 9 10
LT3010-5 GND Pin Current
2.0 TJ = 25C 1.8 *FOR VOUT = 5V 1.6 2.0
GND PIN CURRENT (mA)
1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 1 2
GND PIN CURRENT (mA)
RL = 100 IL = 50mA* RL = 200 IL = 25mA* RL = 500 IL = 10mA* RL = 5k, IL = 1mA* 34567 INPUT VOLTAGE (V) 8 9 10
SHDN PIN THRESHOLD (V)
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UW
3010 G04
3010 G08 3010 G09
LT3010 ADJ Pin Voltage
1.295 1.290 1.285 IL = 1mA 5.08 5.06 5.04 5.02 5.00 4.98 4.96 4.94
LT3010-5 Output Voltage
IL = 1mA
4.92 - 50 - 25
0
75 50 25 TEMPERATURE (C)
100
125
3010 G06
3010 G05
LT3010-5 Quiescent Current
TJ = 25C 180 RL = 160 140 120 100 80 60 40 20 0 0 1 2 VSHDN = VIN VSHDN = 0V 34567 INPUT VOLTAGE (V) 8 9 10 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0
LT3010 GND Pin Current
TJ = 25C *FOR VOUT = 1.275V RL = 25.5 IL = 50mA* RL = 51 IL = 25mA*
RL = 127 IL = 10mA* RL = 1.27k IL = 1mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10
3010 G07
3010 G10
GND Pin Current vs ILOAD
VIN = VOUT(NOMINAL) + 1V 1.8 TJ = 25C 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 5 10 15 20 25 30 35 40 45 50 OUTPUT CURRENT (mA)
3010 G11
SHDN Pin Threshold
1.6 1.4 OFF-TO-ON 1.2 1.0 0.8 0.6 0.4 0.2 0 - 50 - 25 0 75 50 25 TEMPERATURE (C) 100 125 ON-TO-OFF
3010 G12
3010f
LT3010/LT3010-5 TYPICAL PERFOR A CE CHARACTERISTICS
SHDN Pin Current
0.6 TJ = 25C CURRENT FLOWS 0.5 OUT OF SHDN PIN
0.8
0.6 0.5 0.4 0.3 0.2 0.1
ADJ PIN BIAS CURRENT (nA)
SHDN PIN CURRENT (A)
SHDN PIN CURRENT (A)
0.4 0.3 0.2 0.1 0 0 0.5 1 1.5 2 2.5 3 3.5 4 SHDN PIN VOLTAGE (V) 4.5 5
Current Limit
200
160
160
CURRENT LIMIT (mA)
REVERSE OUTPUT CURRENT (A)
VOUT = 0V 180 TJ = 25C
CURRENT LIMIT (mA)
140 120 100 80 60 40 20 0 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10
Reverse Output Current
24
REVERSE OUTPUT CURRENT (A)
21 18 15 12
VIN = 0V VOUT = VADJ = 1.275V (LT3010) VOUT = VSENSE = 5V (LT3010-5)
RIPPLE REJECTION (dB)
RIPPLE REJECTION (dB)
LT3010-5 9 6 3 0 - 50 - 25 0 75 50 25 TEMPERATURE (C) 100 125 LT3010
UW
3010 G13
3010 G16 3010 G19
SHDN Pin Current
VSHDN = 0V 0.7 CURRENT FLOWS OUT OF SHDN PIN 80 70 60 50 40 30 20 10 0 75 50 25 TEMPERATURE (C) 100 125
ADJ Pin Bias Current
0 - 50 - 25
0 - 50 - 25
0
75 50 25 TEMPERATURE (C)
100
125
3010 G14
3010 G15
Current Limit
200 180 VIN = 7V VOUT = 0V
100 90 80 70 60 50 40
Reverse Output Current
TJ = 25C VIN = 0V CURRENT FLOWS INTO OUTPUT PIN VOUT = VADJ (LT3010) VOUT = VSENSE (LT3010-5)
140 120 100 80 60 40 20 0 -50 -25 50 25 0 75 TEMPERATURE (C) 100 125
ADJ PIN CLAMP (SEE APPLICATIONS INFORMATION)
LT3010 30 20 10 0 0 1 2 345678 OUTPUT VOLTAGE (V) 9 10 LT3010-5
3010 G17
3010 G18
Input Ripple Rejection
80 78 76 74 72 70 68 66 64 62 VIN = 7V + 0.5VP-P RIPPLE AT f = 120Hz IL = 50mA VOUT = 1.275V 50 25 0 75 TEMPERATURE (C) 100 125 100 90 80 70 60 50 40 30 20 10 0
Input Ripple Rejection
VIN = 7V + 50mVRMS RIPPLE IL = 50mA
COUT = 10F
COUT = 1F
60 -50 -25
10
100
1k 10k FREQUENCY (Hz)
100k
1M
3010 G21
3010 G20
3010f
5
LT3010/LT3010-5 TYPICAL PERFOR A CE CHARACTERISTICS
LT3010 Minimum Input Voltage
4.0 3.5 ILOAD = 50mA 0 -5 LT3010
LOAD REGULATION (mV)
IL = 1mA TO 50mA
OUTPUT NOISE SPECTRAL DENSITY (V/Hz)
MINIMUM INPUT VOLTAGE (V)
3.0 2.5 2.0 1.5 1.0 0.5 0 - 50 - 25 0 75 50 25 TEMPERATURE (C) 100 125
LT3010-5 10Hz to 100kHz Output Noise
OUTPUT VOLTAGE DEVIATION (V)
0.2 0.1 0 -0.1 -0.2
VOUT 100V/DIV
LOAD CURRENT (mA)
COUT = 1F IL = 50mA
6
UW
3010 G22
Load Regulation
10
Output Noise Spectral Density
COUT = 1F IL = 50mA
-10 -15 LT3010-5 -20 -25 -30 -35 -40 - 50 - 25 0 75 50 25 TEMPERATURE (C) 100 125
1
0.1
0.01 10 100 1k 10k FREQUENCY (Hz) 100k
3010 G24
3010 G23
LT3010-5 Transient Response
50 25 0 0 200
VIN = 6V CIN = 1F CERAMIC COUT = 1F CERAMIC ILOAD = 1mA TO 50mA
1ms/DIV
3010 G25
600 400 TIME (s)
800
1000
3010 G26
3010f
LT3010/LT3010-5
PI FU CTIO S
OUT (Pin 1): Output. The output supplies power to the load. A minimum output capacitor of 1F is required to prevent oscillations. Larger output capacitors will be required for applications with large transient loads to limit peak voltage transients. See the Applications Information section for more information on output capacitance and reverse output characteristics. SENSE (Pin 2): Sense. For the LT3010-5, the SENSE pin is the input to the error amplifier. Optimum regulation will be obtained at the point where the SENSE pin is connected to the OUT pin of the regulator. In critical applications, small voltage drops are caused by the resistance (RP) of PC traces between the regulator and the load. These may be eliminated by connecting the SENSE pin to the output at the load as shown in Figure 1 (Kelvin Sense Connection). Note that the voltage drop across the external PC traces will add to the dropout voltage of the regulator. The SENSE pin bias current is 10A at the nominal rated output voltage. ADJ (Pin 2): Adjust. For the adjustable LT3010, this is the input to the error amplifier. This pin is internally clamped to 7V. It has a bias current of 50nA which flows into the pin (see curve of ADJ Pin Bias Current vs Temperature in
8 IN OUT LT3010 SHDN SENSE GND 4, TAB
3010 F01
VIN
+
Figure 1. Kelvin Sense Connection
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the Typical Performance Characteristics). The ADJ pin voltage is 1.275V referenced to ground, and the output voltage range is 1.275V to 60V. GND (Pin 4, Tab): Ground. The exposed backside of the package is an electrical connection for GND. As such, to ensure optimum device operation, the exposed pad must be connected directly to pin 4 on the PC board. SHDN (Pin 5): Shutdown. The SHDN pin is used to put the LT3010 into a low power shutdown state. The output will be off when the SHDN pin is pulled low. The SHDN pin can be driven either by 5V logic or open-collector logic with a pull-up resistor. The pull-up resistor is only required to supply the pull-up current of the open-collector gate, normally several microamperes. If unused, the SHDN pin can be left open circuit. The device will be active, output on, if the SHDN pin is not connected. IN (Pin 8): Input. Power is supplied to the device through the IN pin. A bypass capacitor is required on this pin if the device is more than six inches away from the main input filter capacitor. In general, the output impedance of a battery rises with frequency, so it is advisable to include a bypass capacitor in battery-powered circuits. A bypass capacitor in the range of 1F to 10F is sufficient. The LT3010 is designed to withstand reverse voltages on the IN pin with respect to ground and the OUT pin. In the case of a reversed input, which can happen if a battery is plugged in backwards, the LT3010 will act as if there is a diode in series with its input. There will be no reverse current flow into the LT3010 and no reverse voltage will appear at the load. The device will protect both itself and the load.
1 2
RP
+
LOAD
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LT3010/LT3010-5
APPLICATIO S I FOR ATIO
The LT3010 is a 50mA high voltage low dropout regulator with micropower quiescent current and shutdown. The device is capable of supplying 50mA at a dropout voltage of 300mV. The low operating quiescent current (30A) drops to 1A in shutdown. In addition to the low quiescent current, the LT3010 incorporates several protection features which make it ideal for use in battery-powered systems. The device is protected against both reverse input and reverse output voltages. In battery backup applications where the output can be held up by a backup battery when the input is pulled to ground, the LT3010 acts like it has a diode in series with its output and prevents reverse current flow. Adjustable Operation The adjustable version of the LT3010 has an output voltage range of 1.275V to 60V. The output voltage is set by the ratio of two external resistors as shown in Figure 2. The device servos the output to maintain the voltage at the adjust pin at 1.275V referenced to ground. The current in R1 is then equal to 1.275V/R1 and the current in R2 is the current in R1 plus the ADJ pin bias current. The ADJ pin bias current, 50nA at 25C, flows through R2 into the ADJ pin. The output voltage can be calculated using the formula in Figure 2. The value of R1 should be less than 250k to minimize errors in the output voltage caused by the ADJ pin bias current. Note that in shutdown the output is turned off and the divider current will be zero.
VIN
VOUT = 1.275V 1 + R2 + (IADJ)(R2) R1 VADJ = 1.275V IADJ = 50nA AT 25C OUTPUT RANGE = 1.275V TO 60V
Figure 2. Adjustable Operation
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A small capacitor (C1) placed in parallel with the top resistor (R2) of the output divider is necessary for stability and transient performance of the adjustable LT3010. The impedance of C1 at 10kHz should be less than the value of R1. The adjustable device is tested and specified with the ADJ pin tied to the OUT pin and a 5A DC load (unless otherwise specified) for an output voltage of 1.275V. Specifications for output voltages greater than 1.275V will be proportional to the ratio of the desired output voltage to 1.275V; (VOUT/1.275V). For example, load regulation for an output current change of 1mA to 50mA is -10mV typical at VOUT = 1.275V. At VOUT = 12V, load regulation is: (12V/1.275V) * (-10mV) = -94mV Output Capacitance and Transient Response The LT3010 is designed to be stable with a wide range of output capacitors. The ESR of the output capacitor affects stability, most notably with small capacitors. A minimum output capacitor of 1F with an ESR of 3 or less is recommended to prevent oscillations. The LT3010 is a micropower device and output transient response will be a function of output capacitance. Larger values of output capacitance decrease the peak deviations and provide improved transient response for larger load current changes. Bypass capacitors, used to decouple individual components powered by the LT3010, will increase the effective output capacitor value.
IN OUT LT3010 ADJ GND R1
3010 F02
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R2
C1
+
VOUT
()
3010f
LT3010/LT3010-5
APPLICATIO S I FOR ATIO
Extra consideration must be given to the use of ceramic capacitors. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior across temperature and applied voltage. The most common dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but exhibit strong voltage and temperature coefficients as shown in Figures 3 and 4. When used with a 5V regulator, a 10F Y5V capacitor can exhibit an effective value as low as 1F to 2F over the operating temperature range. The X5R and X7R dielectrics result in more stable characteristics and are more suitable for use as the output capacitor. The X7R type has better stability across temperature, while the X5R is less expensive and is available in higher values. Voltage and temperature coefficients are not the only sources of problems. Some ceramic capacitors have a piezoelectric response. A piezoelectric device generates voltage across its terminals due to mechanical stress,
20 0
BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10F
CHANGE IN VALUE (%)
CHANGE IN VALUE (%)
X5R -20 -40 -60 Y5V -80
-100
0
2
4
8 6 10 12 DC BIAS VOLTAGE (V)
14
16
3010 F03
Figure 3. Ceramic Capacitor DC Bias Characterics
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similar to the way a piezoelectric accelerometer or microphone works. For a ceramic capacitor the stress can be induced by vibrations in the system or thermal transients. Thermal Considerations The power handling capability of the device will be limited by the maximum rated junction temperature (125C). The power dissipated by the device will be made up of two components: 1. Output current multiplied by the input/output voltage differential: IOUT * (VIN - VOUT) and, 2. GND pin current multiplied by the input voltage: IGND * VIN. The GND pin current can be found by examining the GND Pin Current curves in the Typical Performance Characteristics. Power dissipation will be equal to the sum of the two components listed above.
40 20 0 X5R -20 -40 -60 -80 Y5V BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10F -100 50 25 75 -50 -25 0 TEMPERATURE (C) 100 125
3010 F04
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Figure 4. Ceramic Capacitor Temperature Characterics
3010f
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LT3010/LT3010-5
APPLICATIO S I FOR ATIO
The LT3010 series regulators have internal thermal limiting designed to protect the device during overload conditions. For continuous normal conditions the maximum junction temperature rating of 125C must not be exceeded. It is important to give careful consideration to all sources of thermal resistance from junction to ambient. Additional heat sources mounted nearby must also be considered. For surface mount devices, heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. Copper board stiffeners and plated through-holes can also be used to spread the heat generated by power devices. The following table lists thermal resistance for several different board sizes and copper areas. All measurements were taken in still air on 3/32" FR-4 board with one ounce copper.
Table 1. Measured Thermal Resistance
COPPER AREA TOPSIDE 2500 sq mm 1000 sq mm 225 sq mm 100 sq mm BACKSIDE 2500 sq mm 2500 sq mm 2500 sq mm 2500 sq mm BOARD AREA 2500 sq mm 2500 sq mm 2500 sq mm 2500 sq mm THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 40C/W 45C/W 50C/W 62C/W
The thermal resistance junction-to-case (JC), measured at the exposed pad on the back of the die, is 16C/W. Continuous operation at large input/output voltage differentials and maximum load current is not practical due to thermal limitations. Transient operation at high input/ output differentials is possible. The approximate thermal time constant for a 2500sq mm 3/32" FR-4 board with
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maximum topside and backside area for one ounce copper is 3 seconds. This time constant will increase as more thermal mass is added (i.e. vias, larger board, and other components). For an application with transient high power peaks, average power dissipation can be used for junction temperature calculations as long as the pulse period is significantly less than the thermal time constant of the device and board. Calculating Junction Temperature Example 1: Given an output voltage of 5V, an input voltage range of 24V to 30V, an output current range of 0mA to 50mA, and a maximum ambient temperature of 50C, what will the maximum junction temperature be? The power dissipated by the device will be equal to: IOUT(MAX) * (VIN(MAX) - VOUT) + (IGND * VIN(MAX)) where: IOUT(MAX) = 50mA VIN(MAX) = 30V IGND at (IOUT = 50mA, VIN = 30V) = 1mA So: P = 50mA * (30V - 5V) + (1mA * 30V) = 1.28W The thermal resistance will be in the range of 40C/W to 62C/W depending on the copper area. So the junction temperature rise above ambient will be approximately equal to: 1.31W * 50C/W = 65.5C
3010f
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LT3010/LT3010-5
APPLICATIO S I FOR ATIO
The maximum junction temperature will then be equal to the maximum junction temperature rise above ambient plus the maximum ambient temperature or: TJMAX = 50C + 65.5C = 115.5C Example 2: Given an output voltage of 5V, an input voltage of 48V that rises to 72V for 5ms(max) out of every 100ms, and a 5mA load that steps to 50mA for 50ms out of every 250ms, what is the junction temperature rise above ambient? Using a 500ms period (well under the time constant of the board), power dissipation is as follows: P1(48V in, 5mA load) = 5mA * (48V - 5V) + (200A * 48V) = 0.23W P2(48V in, 50mA load) = 50mA * (48V - 5V) + (1mA * 48V) = 2.20W P3(72V in, 5mA load) = 5mA * (72V - 5V) + (200A * 72V) = 0.35W P4(72V in, 50mA load) = 50mA * (72V - 5V) + (1mA * 72V) = 3.42W Operation at the different power levels is as follows: 76% operation at P1, 19% for P2, 4% for P3, and 1% for P4. PEFF = 76%(0.23W) + 19%(2.20W) + 4%(0.35W) + 1%(3.42W) = 0.64W With a thermal resistance in the range of 40C/W to 62C/W, this translates to a junction temperature rise above ambient of 26C to 38C.
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Protection Features The LT3010 incorporates several protection features which make it ideal for use in battery-powered circuits. In addition to the normal protection features associated with monolithic regulators, such as current limiting and thermal limiting, the device is protected against reverse-input voltages, and reverse voltages from output to input. Current limit protection and thermal overload protection are intended to protect the device against current overload conditions at the output of the device. For normal operation, the junction temperature should not exceed 125C. The input of the device will withstand reverse voltages of 80V. Current flow into the device will be limited to less than 6mA (typically less than 100A) and no negative voltage will appear at the output. The device will protect both itself and the load. This provides protection against batteries which can be plugged in backward. The ADJ pin of the adjustable device can be pulled above or below ground by as much as 7V without damaging the device. If the input is left open circuit or grounded, the ADJ pin will act like an open circuit when pulled below ground, and like a large resistor (typically 100k) in series with a diode when pulled above ground. If the input is powered by a voltage source, pulling the ADJ pin below the reference voltage will cause the device to try and force the current limit current out of the output. This will cause the output to go to a unregulated high voltage. Pulling the ADJ pin above the reference voltage will turn off all output current.
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LT3010/LT3010-5
APPLICATIO S I FOR ATIO
In situations where the ADJ pin is connected to a resistor divider that would pull the ADJ pin above its 7V clamp voltage if the output is pulled high, the ADJ pin input current must be limited to less than 5mA. For example, a resistor divider is used to provide a regulated 1.5V output from the 1.22V reference when the output is forced to 60V. The top resistor of the resistor divider must be chosen to limit the current into the ADJ pin to less than 5mA when the ADJ pin is at 7V. The 53V difference between the OUT and ADJ pins divided by the 5mA maximum current into the ADJ pin yields a minimum top resistor value of 10.6k. In circuits where a backup battery is required, several different input/output conditions can occur. The output voltage may be held up while the input is either pulled to ground, pulled to some intermediate voltage, or is left
100
REVERSE OUTPUT CURRENT (A)
TA = 25C 90 VIN = 0V CURRENT FLOWS 80 INTO OUTPUT PIN 70 VOUT = VADJ (LT3010) VOUT = VSENSE 60 (LT3010-5) 50 40 30 20 10 0 0 1 2 LT3010-5 LT3010
Figure 5. Reverse Output Current
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open circuit. Current flow back into the output will follow the curve shown in Figure 5. The rise in reverse output current above 7V occurs from the breakdown of the 7V clamp on the ADJ pin. With a resistor divider on the regulator output, this current will be reduced depending on the size of the resistor divider. When the IN pin of the LT3010 is forced below the OUT pin or the OUT pin is pulled above the IN pin, input current will typically drop to less than 2A. This can happen if the input of the LT3010 is connected to a discharged (low voltage) battery and the output is held up by either a backup battery or a second regulator circuit. The state of the SHDN pin will have no effect on the reverse output current when the output is pulled above the input.
ADJ PIN CLAMP (SEE ABOVE) 345678 OUTPUT VOLTAGE (V) 9 10
3010 F05
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LT3010/LT3010-5
TYPICAL APPLICATIO S
5V Buck Converter with Low Current Keep Alive Backup
D2 D1N914 6 VIN 5.5V* TO 60V BOOST 4 C3 4.7F 100V CERAMIC VIN LT1766 15 14 SHDN SYNC GND BIAS FB VC CC 1nF 10 12 R1 15.4k R2 4.99k SW 2 C2 0.33F
OPERATING CURRENT LOW HIGH
EFFICIENCY (%)
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L1 15H
D1 10MQ060N
VOUT 5V 1A/50mA
+
C1 100F 10V SOLID TANTALUM
1, 8, 9, 16 11
8 5
IN LT3010-5 SHDN GND 4
OUT SENSE
1 2 * FOR INPUT VOLTAGES BELOW 7.5V, SOME RESTRICTIONS MAY APPLY INCREASE L1 TO 30H FOR LOAD CURRENTS ABOVE 0.6A AND TO 60H ABOVE 1A
3010 TA03
Buck Converter Efficiency vs Load Current
100 VOUT = 5V L = 68H
VIN = 10V
90 VIN = 42V 80
70
60
50
0
0.25
0.75 1.00 0.50 LOAD CURRENT (A)
1.25
3010 TA04
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LT3010/LT3010-5
TYPICAL APPLICATIO U
LT3010 Automotive Application
IN 1F NO PROTECTION DIODE NEEDED! LT3010-5 SHDN SENSE GND OFF ON OUT 1F LOAD: CLOCK, SECURITY SYSTEM ETC
VIN 12V (LATER 42V)
+
LT3010 Telecom Application
VIN 48V (72V TRANSIENT) 1F
IN LT3010-5 SHDN
OUT NO PROTECTION DIODE NEEDED! 1F LOAD: SYSTEM MONITOR ETC
+ -
SENSE GND
BACKUP BATTERY
OFF ON
3010 TA05
Constant Brightness for Indicator LED over Wide Input Voltage Range
RETURN 1F OFF ON
IN
OUT LT3010
SHDN GND
ADJ RSET
3010 TA06
1F
-48V ILED = 1.275V/RSET -48V CAN VARY FROM -4V TO -80V
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LT3010/LT3010-5
PACKAGE DESCRIPTIO U
MS8E Package 8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1662)
BOTTOM VIEW OF EXPOSED PAD OPTION 1 2.794 0.102 (.110 .004) 0.889 0.127 (.035 .005) 2.06 0.102 (.080 .004) 1.83 0.102 (.072 .004) 2.083 0.102 3.2 - 3.45 (.082 .004) (.126 - .136) 8 0.42 0.04 (.0165 .0015) TYP 0.65 (.0256) BSC 3.00 0.102 (.118 .004) (NOTE 3) 0.52 (.206) REF 8 7 65 DETAIL "A" 0 - 6 TYP 4.90 0.15 (1.93 .006) 3.00 0.102 (.118 .004) NOTE 4 0.53 0.015 (.021 .006) DETAIL "A" 0.18 (.077) SEATING PLANE 0.22 - 0.38 (.009 - .015) TYP 0.13 0.076 (.005 .003)
MSOP (MS8E) 0802
5.23 (.206) MIN
RECOMMENDED SOLDER PAD LAYOUT
0.254 (.010) GAUGE PLANE
1 1.10 (.043) MAX
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4 0.86 (.034) REF
NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
0.65 (.0256) BSC
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LT3010/LT3010-5 RELATED PARTS
PART NUMBER LT1020 DESCRIPTION 125mA, Micropower Regulator and Comparator COMMENTS VIN: 4.5V to 36V, VOUT = 2.5V, VDO = 0.4V, IQ = 40A, ISD = 40A, Comparator and Reference, Class B Outputs, S16, PDIP14 Packages VIN: 4.5V to 36V, VOUT = 2.5V, VDO = 0.4V, IQ = 40A, ISD = 10A, Comparator and Reference,Logic Shutdown, Ref Sources and Sinks 2/4mA, S8, N8 Packages VIN: 4.2V to 30/36V, VOUT = 3.75V, VDO = 0.42V, IQ = 30A, ISD = 16A, Reverse Battery Protection, SOT-223, S8, Z Packages VIN: 4.2V to 30V, VOUT = 3.75V, VDO = 0.4V, IQ = 50A, ISD = 16A, DD, S0T-223, S8,TO220-5, TSSOP20 Packages VIN: 3.6V to 25V, VOUT = 1.25V, IQ = 1.9mA, ISD = <1A, ThinSOT Package VIN: 7.4V to 60V, VOUT = 1.24V, IQ = 3.2mA, ISD = 2.5A, S8 Package VIN: 1.8V to 20V, VOUT = 1.22V, VDO = 0.3V, IQ = 20A, ISD = <1A, Low Noise < 20VRMS P-P, Stable with 1F Ceramic Capacitors, ThinSOT Package VIN: 1.8V to 20V, VOUT = 1.22V, VDO = 0.3V, IQ = 25A, ISD = <1A, Low Noise < 20VRMS P-P, MS8 Package VIN: 1.8V to 20V, VOUT = 1.22V, VDO = 0.3V, IQ = 30A, ISD = <1A, Low Noise < 20VRMS P-P, S8 Package VIN: 2.7V to 20V, VOUT = 1.21V, VDO = 0.34V, IQ = 1mA, ISD = <1A, Low Noise < 40VRMS P-P, "A" Version Stable with Ceramic Capacitors, DD, TO220-5 Packages VIN: 5.5V to 60V, VOUT = 1.20V, IQ = 2.5mA, ISD = 25A, TSSOP16/E Package VIN: 7.4V to 40V, VOUT = 1.24V, IQ = 3.2mA, ISD = 30A, N8, S8 Packages 90% Efficiency, VIN: 3.2V to 34V, VOUT = 1.25V, IQ = 14A, ISD = <1A, ThinSOT Package VIN: 5.5V to 60V, VOUT = 1.20V, IQ = 2.5mA, ISD = 25A, TSSOP16/E Package VIN: 1.8V to 20V, VOUT = 1.22V, VDO = 0.27V, IQ = 30A, ISD = <1A, Low Noise < 20VRMS P-P, MS8 Package VIN: 2.1V to 20V, VOUT = 1.21V, VDO = 0.34V, IQ = 1mA, ISD = <1A, Low Noise < 40VRMS P-P, "A" Version Stable with Ceramic Capacitors, DD, TO220-5, S0T-223, S8 Packages VIN: -0.9V to -20V, VOUT = -1.21V, VDO = 0.34V, IQ = 30A, ISD = 3A, Low Noise < 30VRMS P-P, Stable with Ceramic Capacitors, ThinSOT Package
LT1120/LT1120A 125mA, Micropower Regulator and Comparator
LT1121/ LT1121HV LT1129 LT1616 LT1676 LT1761 LT1762 LT1763
150mA, Micropower, LDO 700mA, Micropower, LDO 25V, 500mA (IOUT), 1.4MHz, High Efficiency Step-Down DC/DC Converter 60V, 440mA (IOUT), 100kHz, High Efficiency Step-Down DC/DC Converter 100mA, Low Noise Micropower, LDO 150mA, Low Noise Micropower, LDO 500mA, Low Noise Micropower, LDO
LT1764/LT1764A 3A, Low Noise, Fast Transient Response, LDO
LT1766 LT1776 LT1934/ LT1934-1 LT1956 LT1962
60V, 1.2A (IOUT), 200kHz, High Efficiency Step-Down DC/DC Converter 40V, 550mA (IOUT), 200kHz, High Efficiency Step-Down DC/DC Converter 300mA/60mA, (IOUT), Constant Off-Time, High Efficiency Step-Down DC/DC Converter 60V, 1.2A (IOUT), 500kHz, High Efficiency Step-Down DC/DC Converter 300mA, Low Noise Micropower, LDO
LT1963/LT1963A 1.5A, Low Noise, Fast Transient Response, LDO
LT1964
200mA, Low Noise Micropower, Negative LDO
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507
q
LT/TP 0403 2K * PRINTED IN USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2003

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