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LT1763 Series 500mA, Low Noise, LDO Micropower Regulators FEATURES
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DESCRIPTION
The LT(R)1763 series are micropower, low noise, low dropout regulators. The devices are capable of supplying 500mA of output current with a dropout voltage of 300mV. Designed for use in battery-powered systems, the low 30A quiescent current makes them an ideal choice. Quiescent current is well controlled; it does not rise in dropout as it does with many other regulators. A key feature of the LT1763 regulators is low output noise. With the addition of an external 0.01F bypass capacitor, output noise drops to 20VRMS over a 10Hz to 100kHz bandwidth. The LT1763 regulators are stable with output capacitors as low as 3.3F. Small ceramic capacitors can be used without the series resistance required by other regulators. Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting and reverse current protection. The parts come in fixed output voltages of 1.5V, 1.8V, 2.5V, 3V, 3.3V and 5V, and as an adjustable device with a 1.22V reference voltage. The LT1763 regulators are available in 8-lead SO and 12-lead, low profile (4mm x 3mm x 0.75mm) DFN packages.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6144250, 6118263.
Low Noise: 20VRMS (10Hz to 100kHz) Output Current: 500mA Low Quiescent Current: 30A Wide Input Voltage Range: 1.8V to 20V Low Dropout Voltage: 300mV Very Low Shutdown Current: < 1A No Protection Diodes Needed Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3V, 3.3V, 5V Adjustable Output from 1.22V to 20V Stable with 3.3F Output Capacitor Stable with Aluminum, Tantalum or Ceramic Capacitors Reverse Battery Protection No Reverse Current Overcurrent and Overtemperature Protected 8-Lead SO and 12-Lead (4mm x 3mm) DFN Packages
APPLICATIONS
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Cellular Phones Battery-Powered Systems Noise-Sensitive Instrumentation Systems
TYPICAL APPLICATION
3.3V Low Noise Regulator
DROPOUT VOLTAGE (mV) 3.3V AT 500mA 20VRMS NOISE 10F 0.01F 400 350 VIN 3.7V TO 20V IN 1F OUT SENSE LT1763-3.3 SHDN BYP GND
1763 TA01
Dropout Voltage
+
300 250 200 150 100 50 0 0 100 300 400 200 OUTPUT CURRENT (mA) 500
1763 TA02
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LT1763 Series ABSOLUTE MAXIMUM RATINGS
(Note 1)
IN Pin Voltage ........................................................ 20V OUT Pin Voltage ..................................................... 20V Input to Output Differential Voltage ........................ 20V SENSE Pin Voltage ............................................... 20V ADJ Pin Voltage ...................................................... 7V BYP Pin Voltage .....................................................0.6V SHDN Pin Voltage ................................................ 20V Output Short-Circuit Duration ........................ Indefinite
Operating Junction Temperature Range (Note 2) C, I Grade...........................................-40C to 125C MP Grade...........................................-55C to 125C Storage Temperature Range S8 Package ........................................-65C to 150C DFN Package......................................-65C to 150C Lead Temperature (Soldering, 10 sec) S8 Package ....................................................... 300C
PIN CONFIGURATION
TOP VIEW NC OUT OUT NC SENSE/ADJ* BYP 1 2 3 4 5 6 13 12 NC 11 IN 10 IN 9 8 7 NC SHDN GND S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 150C, JA = 70C/W, JC = 35C/W *PIN 2: SENSE FOR LT1763-1.5/LT1763-1.8/LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5 ADJ FOR LT1763 SEE THE APPLICATIONS INFORMATION SECTION. OUT 1 SENSE/ADJ* 2 GND 3 BYP 4 TOP VIEW 8 7 6 5 IN GND GND SHDN
DE PACKAGE 12-LEAD (4mm 3mm) PLASTIC DFN TJMAX = 125C, JA = 40C/W, JC = 5C/W EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB *PIN 5: SENSE FOR LT1763-1.5/LT1763-1.8/LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5 ADJ FOR LT1763 SEE THE APPLICATIONS INFORMATION SECTION.
ORDER INFORMATION
LEAD FREE FINISH LT1763CDE#PBF LT1763CDE-1.5#PBF LT1763CDE-1.8#PBF LT1763CDE-2.5#PBF LT1763CDE-3#PBF LT1763CDE-3.3#PBF LT1763CDE-5#PBF LT1763CS8#PBF LT1763IS8#PBF LT1763MPS8#PBF TAPE AND REEL LT1763CDE#TRPBF LT1763CDE-1.5#TRPBF LT1763CDE-1.8#TRPBF LT1763CDE-2.5#TRPBF LT1763CDE-3#TRPBF LT1763CDE-3.3#TRPBF LT1763CDE-5#TRPBF LT1763CS8#TRPBF LT1763IS8#TRPBF LT1763MPS8#TRPBF PART MARKING* 1763 76315 76318 76325 17633 76333 17635 1763 1763 1763MP PACKAGE DESCRIPTION 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO TEMPERATURE RANGE -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -55C to 125C
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LT1763 Series ORDER INFORMATION
LEAD FREE FINISH LT1763CS8-1.5#PBF LT1763IS8-1.5#PBF LT1763CS8-1.8#PBF LT1763IS8-1.8#PBF LT1763CS8-2.5#PBF LT1763IS8-2.5#PBF LT1763CS8-3#PBF LT1763IS8-3#PBF LT1763CS8-3.3#PBF LT1763IS8-3.3#PBF LT1763CS8-5#PBF LT1763IS8-5#PBF LEAD BASED FINISH LT1763CDE LT1763CDE-1.5 LT1763CDE-1.8 LT1763CDE-2.5 LT1763CDE-3 LT1763CDE-3.3 LT1763CDE-5 LT1763CS8 LT1763IS8 LT1763MPS8 LT1763CS8-1.5 LT1763IS8-1.5 LT1763CS8-1.8 LT1763IS8-1.8 LT1763CS8-2.5 LT1763IS8-2.5 LT1763CS8-3 LT1763IS8-3 LT1763CS8-3.3 LT1763IS8-3.3 LT1763CS8-5 LT1763IS8-5 TAPE AND REEL LT1763CS8-1.5#TRPBF LT1763IS8-1.5#TRPBF LT1763CS8-1.8#TRPBF LT1763IS8-1.8#TRPBF LT1763CS8-2.5#TRPBF LT1763IS8-2.5#TRPBF LT1763CS8-3#TRPBF LT1763IS8-3#TRPBF LT1763CS8-3.3#TRPBF LT1763IS8-3.3#TRPBF LT1763CS8-5#TRPBF LT1763IS8-5#TRPBF TAPE AND REEL LT1763CDE#TR LT1763CDE-1.5#TR LT1763CDE-1.8#TR LT1763CDE-2.5#TR LT1763CDE-3#TR LT1763CDE-3.3#TR LT1763CDE-5#TR LT1763CS8#TR LT1763IS8#TR LT1763MPS8#TR LT1763CS8-1.5#TR LT1763IS8-1.5#TR LT1763CS8-1.8#TR LT1763IS8-1.8#TR LT1763CS8-2.5#TR LT1763IS8-2.5#TR LT1763CS8-3#TR LT1763IS8-3#TR LT1763CS8-3.3#TR LT1763IS8-3.3#TR LT1763CS8-5#TR LT1763IS8-5#TR PART MARKING* 176315 176315 176318 176318 176325 176325 17633 17633 176333 176333 17635 17635 PART MARKING* 1763 76315 76318 76325 17633 76333 17635 1763 1763 1763MP 176315 176315 176318 176318 176325 176325 17633 17633 176333 176333 17635 17635 PACKAGE DESCRIPTION 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO PACKAGE DESCRIPTION 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 12-Lead (4mm x 3mm) Plastic DFN 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO 8-Lead Plastic SO TEMPERATURE RANGE -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C TEMPERATURE RANGE -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -55C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C -40C to 125C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
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LT1763 Series ELECTRICAL CHARACTERISTICS
PARAMETER Minimum Operating Voltage Regulated Output Voltage (Note 4) CONDITIONS C, I Grade: ILOAD = 500mA (Notes 3, 11) MP Grade: ILOAD = 500mA (Notes 3, 11) LT1763-1.5 LT1763-1.8 LT1763-2.5 LT1763-3 LT1763-3.3 LT1763-5 ADJ Pin Voltage (Notes 3, 4) Line Regulation LT1763 VIN = 2V, ILOAD = 1mA 2.5V < VIN < 20V, 1mA < ILOAD < 500mA VIN = 2.3V, ILOAD = 1mA 2.8V < VIN < 20V, 1mA < ILOAD < 500mA VIN = 3V, ILOAD = 1mA 3.5V < VIN < 20V, 1mA < ILOAD < 500mA VIN = 3.5V, ILOAD = 1mA 4V < VIN < 20V, 1mA < ILOAD < 500mA VIN = 3.8V, ILOAD = 1mA 4.3V < VIN < 20V, 1mA < ILOAD < 500mA VIN = 5.5V, ILOAD = 1mA 6V < VIN < 20V, 1mA < ILOAD < 500mA VIN = 2.2V, ILOAD = 1mA C, I Grade: 2.3V < VIN < 20V, 1mA < ILOAD < 500mA MP Grade: 2.35V < VIN < 20V, 1mA < ILOAD < 500mA VIN = 2V to 20V, ILOAD = 1mA VIN = 2.3V to 20V, ILOAD = 1mA VIN = 3V to 20V, ILOAD = 1mA VIN = 3.5V to 20V, ILOAD = 1mA VIN = 3.8V to 20V, ILOAD = 1mA VIN = 5.5V to 20V, ILOAD = 1mA C, I Grade: VIN = 2V to 20V, ILOAD = 1mA MP Grade: VIN = 2.1V to 20V, ILOAD = 1mA VIN = 2.5V, ILOAD = 1mA to 500mA VIN = 2.5V, ILOAD = 1mA to 500mA VIN = 2.8V, ILOAD = 1mA to 500mA VIN = 2.8V, ILOAD = 1mA to 500mA VIN = 3.5V, ILOAD = 1mA to 500mA VIN = 3.5V, ILOAD = 1mA to 500mA VIN = 4V, ILOAD = 1mA to 500mA VIN = 4V, ILOAD = 1mA to 500mA VIN = 4.3V, ILOAD = 1mA to 500mA VIN = 4.3V, ILOAD = 1mA to 500mA VIN = 6V, ILOAD= 1mA to 500mA VIN = 6V, ILOAD = 1mA to 500mA
l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 2)
MIN TYP 1.8 1.8 1.485 1.462 1.782 1.755 2.475 2.435 2.970 2.925 3.267 3.220 4.950 4.875 1.208 1.190 1.190 1.5 1.5 1.8 1.8 2.5 2.5 3 3 3.3 3.3 5 5 1.220 1.220 1.220 1 1 1 1 1 1 1 1 3 4 5 7 7 12 2 MAX 2.3 2.35 1.515 1.538 1.818 1.845 2.525 2.565 3.030 3.075 3.333 3.380 5.050 5.125 1.232 1.250 1.250 5 5 5 5 5 5 5 5 8 15 9 18 12 25 15 30 17 33 25 50 6 12 12 0.19 0.25 0.22 0.32 0.24 0.34 0.35 0.45 UNITS V V V V V V V V V V V V V V V V V mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV V V V V V V V V
LT1763-1.5 LT1763-1.8 LT1763-2.5 LT1763-3 LT1763-3.3 LT1763-5 LT1763 (Note 3) LT1763 (Note 3) LT1763-1.5 LT1763-1.8 LT1763-2.5 LT1763-3 LT1763-3.3 LT1763-5
Load Regulation
LT1763 (Note 3) VIN = 2.3V, ILOAD = 1mA to 500mA C, I Grade: VIN = 2.3V, ILOAD = 1mA to 500mA MP Grade: VIN = 2.35V, ILOAD = 1mA to 500mA Dropout Voltage VIN = VOUT(NOMINAL) (Notes 5, 6, 11) ILOAD = 10mA ILOAD = 10mA ILOAD = 50mA ILOAD = 50mA ILOAD = 100mA ILOAD = 100mA ILOAD = 500mA ILOAD = 500mA
0.13 0.17 0.20 0.30
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LT1763 Series ELECTRICAL CHARACTERISTICS
PARAMETER GND Pin Current VIN = VOUT(NOMINAL) (Notes 5, 7) CONDITIONS ILOAD = 0mA ILOAD = 1mA ILOAD = 50mA ILOAD = 100mA ILOAD = 250mA ILOAD = 500mA COUT = 10F, CBYP = 0.01F, ILOAD = 500mA, BW = 10Hz to 100kHz (Notes 3, 8) VOUT = Off to On VOUT = On to Off VSHDN = 0V VSHDN = 20V VIN = 6V, VSHDN = 0V VIN - VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 500mA VIN = 7V, VOUT = 0V C, I Grade: VIN = VOUT(NOMINAL) + 1V or 2.3V (Note 12), VOUT = -0.1V MP Grade: VIN = 2.35V (Note 12), VOUT = -0.1V VIN = -20V, VOUT = 0V LT1763-1.5 LT1763-1.8 LT1763-2.5 LT1763-3 LT1763-3.3 LT1763-5 LT1763 (Note 3) VOUT = 1.5V, VIN < 1.5V VOUT = 1.8V, VIN < 1.8V VOUT = 2.5V, VIN < 2.5V VOUT = 3V, VIN < 3V VOUT = 3.3V, VIN < 3.3V VOUT = 5V, VIN < 5V VOUT = 1.22V, VIN < 1.22V
l l l l l l l l l l l
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. (Note 2)
MIN TYP 30 65 1.1 2 5 11 20 30 0.25 0.8 0.65 0.1 1 0.1 50 65 1 100 2 MAX 75 120 1.6 3 8 16 UNITS A A mA mA mA mA VRMS nA V V A A A dB
Output Voltage Noise ADJ Pin Bias Current Shutdown Threshold SHDN Pin Current (Note 9) Quiescent Current in Shutdown Ripple Rejection Current Limit
520 520 1 10 10 10 10 10 10 5 20 20 20 20 20 20 10
mA mA mA A A A A A A A
Input Reverse Leakage Current Reverse Output Current (Note 10)
Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT1763 regulators are tested and specified under pulse load conditions such that TJ TA. The LT1763 (C grade) is 100% tested at TA = 25C; performance at -40C and 125C is assured by design, characterization and correlation with statistical process controls. The LT1763 (I grade) is guaranteed over the full -40C to 125C operating junction temperature range. The LT1763 (MP grade) is 100% tested and guaranteed over the -55C to 125C operating junction temperature range. Note 3: The LT1763 (adjustable version) is tested and specified for these conditions with the ADJ pin connected to the OUT pin. Note 4: 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 5: To satisfy requirements for minimum input voltage, the LT1763 (adjustable version) is tested and specified for these conditions with an external resistor divider (two 250k resistors) for an output voltage of 2.44V. The external resistor divider will add a 5A DC load on the output.
Note 6: 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 7: GND pin current is tested with VIN = VOUT(NOMINAL) or VIN = 2.3V (C, I grade) or 2.35V (MP grade), whichever is greater, 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 8: ADJ pin bias current flows into the ADJ pin. Note 9: SHDN pin current flows into the SHDN pin. Note 10: 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 11: For the LT1763, LT1763-1.5 and LT1763-1.8 dropout voltage will be limited by the minimum input voltage specification under some output voltage/load conditions. See the curve of Minimum Input Voltage in the Typical Performance Characteristics. Note 12: To satisfy requirements for minimum input voltage, current limit is tested at VIN = VOUT(NOMINAL) + 1V or 2.3V (C, I grade) or 2.35V (MP grade), whichever is greater.
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LT1763 Series TYPICAL PERFORMANCE CHARACTERISTICS
Typical Dropout Voltage
500 GUARANTEED DROPOUT VOLTAGE (mV) 450 DROPOUT VOLTAGE (mV) 400 350 300 250 200 150 100 50 0 0 50 100 150 200 250 300 350 400 450 500 OUTPUT CURRENT (mA)
1763 G01
Guaranteed Dropout Voltage
500 450 DROPOUT VOLTAGE (mV) 400 350 300 250 200 150 100 50 0 0 50 100 150 200 250 300 350 400 450 500 OUTPUT CURRENT (mA)
1763 G02
Dropout Voltage
500 450 400 350 300 250 200 150 100 50 0 -50 -25 IL = 50mA IL = 10mA 100 125 IL = 1mA IL = 100mA IL = 250mA IL = 500mA
= TEST POINTS
TJ = 125C
TJ
125C
TJ
25C
TJ = 25C
50 25 0 75 TEMPERATURE (C)
1763 G03
Quiescent Current
50 45 QUIESCENT CURRENT (A) 40 35 30 25 20 15 10 VIN = 6V 5 RL = , IL = 0 (LT1763-1.5/-1.8/-2.5/-3/-3.3/-5) RL = 250k, IL = 5A (LT1763) 0 0 25 50 75 100 125 -50 -25 TEMPERATURE (C)
1763 G04
LT1763-1.5 Output Voltage
1.528 IL = 1mA 1.521 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 1.514 1.507 1.500 1.493 1.486 1.479 1.472 -50 -25 0 25 50 75 100 125 1.83 1.82 1.81 1.80 1.79 1.78 1.77 1.84
LT1763-1.8 Output Voltage
IL = 1mA
VSHDN = VIN
1.76 -50
-25
0
25
50
75
100
125
TEMPERATURE (C)
1763 G05
TEMPERATURE (C)
1763 G06
LT1763-2.5 Output Voltage
2.54 IL = 1mA 2.53 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 2.52 2.51 2.50 2.49 2.48 2.47 2.46 -50 -25 0 25 50 75 100 125 3.045 3.030 3.015 3.000 2.985 2.970 2.955 3.060
LT1763-3 Output Voltage
3.360 IL = 1mA 3.345 OUTPUT VOLTAGE (V) 3.330 3.315 3.300 3.285 3.270 3.255 -25 0 25 50 75 100 125
LT1763-3.3 Output Voltage
IL = 1mA
2.940 -50
3.240 -50
-25
0
25
50
75
100
125
TEMPERATURE (C)
1763 G07
TEMPERATURE (C)
1763 G08
TEMPERATURE (C)
1763 G09
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LT1763 Series TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-5 Output Voltage
5.100 IL = 1mA 5.075 OUTPUT VOLTAGE (V) ADJ PIN VOLTAGE (V) 5.050 5.025 5.000 4.975 4.950 4.925 4.900 -50 -25 0 25 50 75 100 125 1.235 1.230 1.225 1.220 1.215 1.210 1.205 1.200 -50 -25 0 25 50 75 100 125 1.240 IL = 1mA QUIESCENT CURRENT (A)
LT1763 ADJ Pin Voltage
250 225 200 175 150 125 100 75 50 25 0
LT1763-1.5 Quiescent Current
TJ = 25C RL =
VSHDN = VIN VSHDN = 0V 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10
TEMPERATURE (C)
1763 G10
TEMPERATURE (C)
1763 G11
1763 G12
LT1763-1.8 Quiescent Current
250 225 QUIESCENT CURRENT (A) 200 175 150 125 100 75 50 25 0 0 1 2 VSHDN = VIN VSHDN = 0V 34567 INPUT VOLTAGE (V) 8 9 10 TJ = 25C RL = QUIESCENT CURRENT (A) 250 225 200 175 150 125 100 75 50 25 0
LT1763-2.5 Quiescent Current
250 TJ = 25C RL = QUIESCENT CURRENT (A) 225 200 175 150 125 100 75 50 25 0 9 10
LT1763-3 Quiescent Current
TJ = 25C RL =
VSHDN = VIN VSHDN = 0V 0 1 2 34567 INPUT VOLTAGE (V) 8
VSHDN = VIN VSHDN = 0V 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10
1763 G13
1763 G14
1763 G15
LT1763-3.3 Quiescent Current
250 225 QUIESCENT CURRENT (A) 200 175 150 125 100 75 50 25 0 0 1 2 VSHDN = VIN VSHDN = 0V 34567 INPUT VOLTAGE (V) 8 9 10 TJ = 25C RL = QUIESCENT CURRENT (A) 250 225 200 175 150 125 100 75 50 25 0
LT1763-5 Quiescent Current
40 TJ = 25C RL = QUIESCENT CURRENT (A) 35 30 25 20 15 10 5 0 9 10
LT1763 Quiescent Current
TJ = 25C RL = 250k VSHDN = VIN
VSHDN = VIN VSHDN = 0V 0 1 2 34567 INPUT VOLTAGE (V) 8
VSHDN = 0V 0 2 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V)
1763 G18
1763 G16
1763 G17
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LT1763 Series TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-1.5 GND Pin Current
1200 1000 GND PIN CURRENT (A) GND PIN CURRENT (A) 800 600 400 200 0 RL = 30 IL = 50mA* 1200 1000 800 600 400 200 0 RL = 36 IL = 50mA* TJ = 25C VIN = VSHDN *FOR VOUT = 1.8V RL = 180 IL = 10mA* RL = 1.8k IL = 1mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 GND PIN CURRENT (A)
LT1763-1.8 GND Pin Current
1200 1000 800 600 400 200 0
LT1763-2.5 GND Pin Current
RL = 50 IL = 50mA* TJ = 25C VIN = VSHDN *FOR VOUT = 2.5V RL = 250 IL = 10mA* RL = 2.5k IL = 1mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10
TJ = 25C VIN = VSHDN *FOR VOUT = 1.5V
RL = 150 IL = 10mA* RL = 1.5k IL = 1mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10
1763 G19
1763 G20
1763 G21
LT1763-3 GND Pin Current
1200 1000 GND PIN CURRENT (A) 800 600 400 200 0 RL = 300 IL = 10mA* RL = 3k IL = 1mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 1200 1000 GND PIN CURRENT (A) 800 600 400 200 0
LT1763-3.3 GND Pin Current
1200 1000 GND PIN CURRENT (A) 800 600 400 200 0
LT1763-5 GND Pin Current
RL = 60 IL = 50mA* TJ = 25C VIN = VSHDN *FOR VOUT = 3V
RL = 66 IL = 50mA* TJ = 25C VIN = VSHDN *FOR VOUT = 3.3V RL = 330 IL = 10mA* RL = 3.3k IL = 1mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10
RL = 100 IL = 50mA* TJ = 25C VIN = VSHDN *FOR VOUT = 5V RL = 500 IL = 10mA* RL = 5k IL = 1mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10
1763 G22
1763 G23
1763 G24
LT1763 GND Pin Current
1200 1000 GND PIN CURRENT (A) 800 600 400 200 0 RL = 122 IL = 10mA* RL = 1.22k IL = 1mA* 0 1 2 34567 INPUT VOLTAGE (V) 8 9 10 TJ = 25C VIN = VSHDN *FOR VOUT = 1.22V RL = 24.4 IL = 50mA* 12 10 GND PIN CURRENT (mA) 8 6 4 2 0
LT1763-1.5 GND Pin Current
12 TJ = 25C VIN = VSHDN *FOR VOUT = 1.5V RL = 3 IL = 500mA* RL = 5 IL = 300mA* GND PIN CURRENT (mA) 10 8 6 4 2 0
LT1763-1.8 GND Pin Current
TJ = 25C VIN = VSHDN *FOR VOUT = 1.8V RL = 3.6 IL = 500mA* RL = 6 IL = 300mA*
RL = 15 IL = 100mA*
RL = 18 IL = 100mA*
0
1
2
34567 INPUT VOLTAGE (V)
8
9
10
0
1
2
34567 INPUT VOLTAGE (V)
8
9
10
1763 G25
1763 G26
1763 G27
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LT1763 Series TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-2.5 GND Pin Current
12 10 GND PIN CURRENT (mA) 8 6 4 2 0 RL = 25 IL = 100mA* RL = 5 IL = 500mA* RL = 8.33 IL = 300mA* TJ = 25C VIN = VSHDN *FOR VOUT = 2.5V GND PIN CURRENT (mA) 12 10 8 6 4 2 0 RL = 30 IL = 100mA* RL = 6 IL = 500mA* RL = 10 IL = 300mA* TJ = 25C VIN = VSHDN *FOR VOUT = 3V GND PIN CURRENT (mA)
LT1763-3 GND Pin Current
12 10 8 6 4 2 0
LT1763-3.3 GND Pin Current
TJ = 25C VIN = VSHDN *FOR VOUT = 3.3V RL = 6.6 IL = 500mA* RL = 11 IL = 300mA* RL = 33 IL = 100mA*
0
1
2
34567 INPUT VOLTAGE (V)
8
9
10
0
1
2
34567 INPUT VOLTAGE (V)
8
9
10
0
1
2
34567 INPUT VOLTAGE (V)
8
9
10
1763 G28
1763 G29
1763 G30
LT1763-5 GND Pin Current
12 10 GND PIN CURRENT (mA) 8 6 4 2 0 RL = 50 IL = 100mA* RL = 16.7 IL = 300mA* TJ = 25C VIN = VSHDN *FOR VOUT = 5V RL = 10 IL = 500mA* 12 10 GND PIN CURRENT (mA) 8 6 4 2 0
LT1763 GND Pin Current
12 TJ = 25C VIN = VSHDN *FOR VOUT = 1.22V RL = 2.44 IL = 500mA* RL = 4.07 IL = 300mA* GND PIN CURRENT (mA)
GND Pin Current vs ILOAD
VIN = VOUT(NOMINAL) + 1V 10 8 6 4 2 0
RL = 12.2 IL = 100mA*
0
1
2
34567 INPUT VOLTAGE (V)
8
9
10
0
1
2
34567 INPUT VOLTAGE (V)
8
9
10
0
50 100 150 200 250 300 350 400 450 500 OUTPUT CURRENT (mA)
1763 G33
1763 G31
1763 G32
SHDN Pin Threshold (On-to-Off)
1.0 0.9 SHDN PIN THRESHOLD (V) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -50 -25 50 25 0 75 TEMPERATURE (C) 100 125 IL = 1mA SHDN PIN THRESHOLD (V) 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1
SHDN Pin Threshold (Off-to-On)
1.4 SHDN PIN INPUT CURRENT (A) 1.2 1.0 0.8 0.6 0.4 0.2 0 -25 50 25 0 75 TEMPERATURE (C) 100 125
SHDN Pin Input Current
IL = 500mA
IL = 1mA
0 -50
0
1
2
345678 SHDN PIN VOLTAGE (V)
9
10
1763 G34
1763 G35
1763 G36
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9
LT1763 Series TYPICAL PERFORMANCE CHARACTERISTICS
SHDN Pin Input Current
1.6 VSHDN = 20V SHDN PIN INPUT CURRENT (A) 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 -50 -25 0 25 50 75 100 125 ADJ PIN BIAS CURRENT (nA) 120 CURRENT LIMIT (A) 100 80 60 40 20 0 -50 140
ADJ Pin Bias Current
1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 -25 50 25 0 75 TEMPERATURE (C) 100 125 0
Current Limit
VOUT = 0V
0
1
TEMPERATURE (C)
1763 G37
4 3 2 5 INPUT VOLTAGE (V)
6
7
1763 G39
1763 G38
Current Limit
1.2 1.0 CURRENT LIMIT (A) 0.8 0.6 0.4 0.2 0 -50 REVERSE OUTPUT CURRENT (A) VIN = 7 VOUT = 0V 100 90 80 70 60 50 40 30 20 10 -25 50 25 0 75 TEMPERATURE (C) 100 125 0
Reverse Output Current
20 REVERSE OUTPUT CURRENT (A) TJ = 25C, VIN = 0V CURRENT FLOWS INTO OUTPUT PIN VOUT = VADJ (LT1763) LT1763 LT1763-1.8 LT1763-2.5 LT1763-3 LT1763-3.3 LT1763-1.5
Reverse Output Current
VIN = 0V, VOUT = 1.22V (LT1763) 18 VOUT = 1.5V (LT1763-1.5) = 1.8V (LT1763-1.8) V 16 VOUT = 2.5V (LT1763-2.5) OUT 14 VOUT = 3V (LT1763-3) VOUT = 3.3V (LT1763-3.3) 12 VOUT = 5V (LT1763-5) 10 8 6 4 2 10 0 -50 -25 50 25 0 75 TEMPERATURE (C) 100 125 LT1763-1.5/-1.8/ -2.5/-3/-3.3/-5 LT1763
LT1763-5 0 1 2 345678 OUTPUT VOLTAGE (V) 9
1763 G40
1763 G41
1763 G42
Input Ripple Rejection
80 70 RIPPLE REJECTION (dB) RIPPLE REJECTION (dB) 60 50 40 30 20 10 0 10 100 1k 10k FREQUENCY (Hz) 100k 1M
1763 G43
Input Ripple Rejection
80 70 CBYP = 0.01F RIPPLE REJECTION (dB) 60 50 CBYP = 1000pF 40 30 20 10 0 10 100 1k 10k FREQUENCY (Hz) 100k 1M
1763 G44
Ripple Rejection
68 66 64 62 60 58 56 54 52 -50 VIN = VOUT (NOMINAL) + 1V + 0.5VP-P RIPPLE AT f = 120Hz IL = 500mA -25 0 25 50 75 100 125
COUT = 10F
CBYP = 100pF
IL = 500mA VIN = VOUT(NOMINAL) + 1V + 50mVRMS RIPPLE CBYP = 0
COUT = 4.7F
IL = 500mA VIN = VOUT(NOMINAL) + 1V + 50mVRMS RIPPLE COUT = 10F
TEMPERATURE (C)
1763 G45
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10
LT1763 Series TYPICAL PERFORMANCE CHARACTERISTICS
LT1763 Minimum Input Voltage
2.50 2.25 MINIMUM INPUT VOLTAGE (V) LOAD REGULATION (mV) 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 VOUT = 1.22V -25 50 25 0 75 TEMPERATURE (C) 100 125 -25 -50 IL = 1mA IL = 500mA 0 -5 -10 -15 -20 LT1763-3 LT1763-3.3 LT1763-5 5 LT1763 LT1763-2.5 LT1763-1.5 LT1763-1.8
Load Regulation
VIN = VOUT(NOMINAL) + 1V IL = 1mA TO 500mA -25 0 25 50 75 100 125
0 -50
TEMPERATURE (C)
1763 G46 1763 G47
Output Noise Spectral Density CBYP = 0
OUTPUT NOISE SPECTRAL DENSITY (V/ Hz) OUTPUT NOISE SPECTRAL DENSITY (V/ Hz) 10 LT1763-3 LT1763-5 1 LT1763-3.3 10
Output Noise Spectral Density
COUT = 10F IL = 500mA LT1763-5 1 LT1763 CBYP = 1000pF CBYP = 100pF
LT1763 0.1
LT1763-2.5 LT1763-1.5 LT1763-1.8
0.1
CBYP = 0.01F
COUT = 10F IL = 500mA 0.01 10 100 1k 10k FREQUENCY (Hz) 100k
1763 G48
0.01 10
100
1k 10k FREQUENCY (Hz)
100k
1763 G49
RMS Output Noise vs Bypass Capacitor
160 140 OUTPUT NOISE (VRMS) 120 100 80 LT1763-2.5 60 40 20 0 10 100 CBYP (pF)
1763 G50
RMS Output Noise vs Load Current (10Hz to 100kHz)
160 140 OUTPUT NOISE (VRMS) 120 LT1763-5 100 80 60 40 20 1000 10000 0 0.01 0.1 LT1763-5 LT1763 10 100 1 LOAD CURRENT (mA) 1000
1763 G51
COUT = 10F IL = 500mA f = 10Hz TO 100kHz LT1763-5 LT1763-3.3 LT1763-3
COUT = 10F CBYP = 0 CBYP = 0.01F
LT1763
LT1763 LT1763-1.8 LT1763-1.5
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11
LT1763 Series TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-5 10Hz to 100kHz Output Noise CBYP = 0 LT1763-5 10Hz to 100kHz Output Noise CBYP = 100pF
VOUT 100V/DIV
VOUT 100V/DIV
COUT = 10F IL = 500mA
1ms/DIV
1763 G52
COUT = 10F IL = 500mA
1ms/DIV
1763 G53
LT1763-5 10Hz to 100kHz Output Noise CBYP = 1000pF
LT1763-5 10Hz to 100kHz Output Noise CBYP = 0.01F
VOUT 100V/DIV
VOUT 100V/DIV
COUT = 10F IL = 500mA
1ms/DIV
1763 G54
COUT = 10F IL = 500mA
1ms/DIV
1763 G55
LT1763-5 Transient Response CBYP = 0
OUTPUT VOLTAGE DEVIATION (V) OUTPUT VOLTAGE DEVIATION (V) 0.4 0.2 0 -0.2 -0.4 VIN = 6V CIN = 10F COUT = 10F 0.10 0.05 0 -0.05 -0.10
LT1763-5 Transient Response CBYP = 0.01F
VIN = 6V CIN = 10F COUT = 10F
LOAD CURRENT (mA)
600 400 200 0 0 200 400 600 TIME (s) 800 1000
1763 G56
LOAD CURRENT (mA)
600 400 200 0 0 10 20 30 40 50 60 70 80 90 100 TIME (s)
1763 G57
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12
LT1763 Series PIN FUNCTIONS
(DE12/S8)
NC (Pins 1, 4, 9, 12) DE12 Only: No Connect. No connect pins have no connection to any internal circuitry. These pins may be tied to either GND or VIN , or left floating. OUT (Pins 2, 3/Pin 1): Output. The output supplies power to the load. A minimum output capacitor of 3.3F 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. ADJ (Pin 5/Pin 2): Adjust. For the adjustable LT1763, this is the input to the error amplifier. This pin is internally clamped to 7V. It has a bias current of 30nA which flows into the pin (see the curve of ADJ Pin Bias Current vs Temperature in the Typical Performance Characteristics section). The ADJ pin voltage is 1.22V referenced to ground and the output voltage range is 1.22V to 20V. SENSE (Pin 5/Pin 2): Output Sense. For fixed voltage versions of the LT1763 (LT1763-1.5/LT1763-1.8/ LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5), 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).
8 IN LT1763 OUT 1 RP
supply system where the regulator load is returned to a negative supply) and still allow the device to start and operate. BYP (Pin 6/Pin 4): Bypass. The BYP pin is used to bypass the reference of the LT1763 regulators to achieve low noise performance from the regulator. The BYP pin is clamped internally to 0.6V (one VBE). A small capacitor from the output to this pin will bypass the reference to lower the output voltage noise. A maximum value of 0.01F can be used for reducing output voltage noise to a typical 20VRMS over a 10Hz to 100kHz bandwidth. If not used, this pin must be left unconnected. GND (Pins 7/Pins 3, 6, 7): Ground. SHDN (Pin 8/Pin 5): Shutdown. The SHDN pin is used to put the LT1763 regulators 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 required to supply the pull-up current of the open-collector gate, normally several microamperes, and the SHDN pin current, typically 1A. If unused, the SHDN pin must be connected to VIN. The device will be in the low power shutdown state if the SHDN pin is not connected. IN (Pin 10, 11/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 LT1763 regulators are designed to withstand reverse voltages on the IN pin with respect to ground and the OUT pin. In the case of a reverse input, which can happen if a battery is plugged in backwards, the device will act as if there is a diode in series with its input. There will be no reverse current flow into the regulator and no reverse voltage will appear at the load. The device will protect both itself and the load. Exposed Pad (Pin 13) DE12 Only: Ground. The Exposed Pad must be soldered to the PCB ground for rated thermal performance.
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+
VIN
5
SHDN
SENSE GND 3
2
+
LOAD
RP
1763 F01
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. The SENSE pin can be pulled below ground (as in a dual
13
LT1763 Series APPLICATIONS INFORMATION
The LT1763 series are 500mA low dropout regulators with micropower quiescent current and shutdown. The devices are capable of supplying 500mA at a dropout voltage of 300mV. Output voltage noise can be lowered to 20VRMS over a 10Hz to 100kHz bandwidth with the addition of a 0.01F reference bypass capacitor. Additionally, the reference bypass capacitor will improve transient response of the regulator, lowering the settling time for transient load conditions. The low operating quiescent current (30A) drops to less than 1A in shutdown. In addition to the low quiescent current, the LT1763 regulators incorporate several protection features which make them ideal for use in battery-powered systems. The devices are 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 LT1763-X acts like it has a diode in series with its output and prevents reverse current flow. Additionally, in dual supply applications where the regulator load is returned to a negative supply, the output can be pulled below ground by as much as 20V and still allow the device to start and operate. Adjustable Operation The adjustable version of the LT1763 has an output voltage range of 1.22V to 20V. 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 ADJ pin voltage at 1.22V referenced to ground. The current in R1 is then equal to 1.22V/R1 and the current in R2 is the current in R1 plus the ADJ pin bias current. The ADJ pin bias current, 30nA 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 no greater 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. Curves of ADJ Pin Voltage vs Temperature and ADJ Pin Bias Current vs Temperature appear in the Typical Performance Characteristics section. The adjustable device is tested and specified with the ADJ pin tied to the OUT pin for an output voltage of 1.22V. Specifications for output voltages greater than 1.22V will be proportional to the ratio of the desired output voltage
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to 1.22V: VOUT /1.22V. For example, load regulation for an output current change of 1mA to 500mA is -2mV typical at VOUT = 1.22V. At VOUT = 12V, load regulation is: (12V/1.22V)(-2mV) = -19.6mV
IN VIN LT1763
OUT
VOUT
+
R2 ADJ R1
1763 F02
GND
R2 VOUT = 1.22V 1 + + (IADJ )(R2) R1 VADJ = 1.22V IADJ = 30nA AT 25C OUTPUT RANGE = 1.22V TO 20V
Figure 2. Adjustable Operation
Bypass Capacitance and Low Noise Performance The LT1763 regulators may be used with the addition of a bypass capacitor from VOUT to the BYP pin to lower output voltage noise. A good quality low leakage capacitor is recommended. This capacitor will bypass the reference of the regulator, providing a low frequency noise pole. The noise pole provided by this bypass capacitor will lower the output voltage noise to as low as 20VRMS with the addition of a 0.01F bypass capacitor. Using a bypass capacitor has the added benefit of improving transient response. With no bypass capacitor and a 10F output capacitor, a 10mA to 500mA load step will settle to within 1% of its final value in less than 100s. With the addition of a 0.01F bypass capacitor, the output will settle to within 1% for a 10mA to 500mA load step in less than 10s, with total output voltage deviation of less than 2.5% (see the LT1763-5 Transient Response curve in the Typical Performance Characteristics section). However, regulator start-up time is proportional to the size of the bypass capacitor, slowing to 15ms with a 0.01F bypass capacitor and 10F output capacitor.
14
LT1763 Series APPLICATIONS INFORMATION
Output Capacitance and Transient Response The LT1763 regulators are 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 3.3F with an ESR of 3, or less, is recommended to prevent oscillations. The LT1763-X 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 LT1763-X, will increase the effective output capacitor value. With larger capacitors used to bypass the reference (for low noise operation), larger values of output capacitors are needed. For 100pF of bypass capacitance, 4.7F of output capacitor is recommended. With a 1000pF bypass capacitor or larger, a 6.8F output capacitor is recommended. The shaded region of Figure 3 defines the range over which the LT1763 regulators are stable. The minimum ESR needed is defined by the amount of bypass capacitance used, while the maximum ESR is 3. 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 specified with EIA temperature characteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but they tend to have strong voltage and temperature coefficients, as shown in Figures 4 and 5. When used with a 5V regulator, a 16V 10F Y5V capacitor can exhibit an effective value as low as 1F to 2F for the DC bias voltage applied and 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. Care still must be exercised when using X5R and X7R capacitors; the X5R and X7R codes only specify operating temperature range and maximum capacitance change over temperature. Capacitance change due to DC bias with X5R and X7R capacitors is better than
4.0 3.5 3.0 STABLE REGION 2.5 ESR () 2.0 1.5 1.0 0.5 0 1 3 2 4 5 6 7 8 9 10 OUTPUT CAPACITANCE (F) 1763 F03 CBYP = 0 CBYP = 100pF CBYP = 330pF CBYP 1000pF
Figure 3. Stability
20 0 CHANGE IN VALUE (%)
BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10F X5R
-20 -40 -60 Y5V -80
-100
0
2
4
6
8
10
12
14
16
1763 F04
DC BIAS VOLTAGE (V)
Figure 4. Ceramic Capacitor DC Bias Characteristics
40 20 CHANGE IN VALUE (%) 0 -20 -40 -60 -80 BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10F 50 25 75 0 TEMPERATURE (C) 100 125
1763 F05
X5R
Y5V
-100 -50 -25
Figure 5. Ceramic Capacitor Temperature Characteristics
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15
LT1763 Series APPLICATIONS INFORMATION
Y5V and Z5U capacitors, but can still be significant enough to drop capacitor values below appropriate levels. Capacitor DC bias characteristics tend to improve as component case size increases, but expected capacitance at operating voltage should be verified. 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, 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. The resulting voltages produced can cause appreciable amounts of noise, especially when a ceramic capacitor is used for noise bypassing. A ceramic capacitor produced Figure 6's trace in response to light tapping from a pencil. Similar vibration induced behavior can masquerade as increased output voltage noise.
LT1763-5 COUT = 10F CBYP = 0.01F ILOAD = 100mA VOUT 500V/DIV
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 section. Power dissipation will be equal to the sum of the two components listed above. The LT1763 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.
100ms/DIV
1763 F06
Figure 6. Noise Resulting from Tapping on a Ceramic Capacitor
The following tables list 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. DE Package, 12-Lead DFN
COPPER AREA TOPSIDE* 2500mm2 1000mm2 225mm2 100mm2 BACKSIDE 2500mm2 2500mm2 2500mm2 2500mm2 BOARD AREA 2500mm2 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 40C/W 45C/W 50C/W 60C/W
* Device is mounted on topside
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16
LT1763 Series APPLICATIONS INFORMATION
Table 2. SO-8 Package, 8-Lead SO
COPPER AREA TOPSIDE* 2500mm2 1000mm2 225mm2 100mm2 50mm2 BACKSIDE 2500mm2 2500mm2 2500mm2 2500mm2 2500mm2 BOARD AREA 2500mm2 2500mm2 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 60C/W 60C/W 68C/W 74C/W 86C/W
Protection Features The LT1763 regulators incorporate several protection features which make them 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 devices are protected against reverse input voltages, reverse output 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 20V. Current flow into the device will be limited to less than 1mA (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 output of the LT1763-X can be pulled below ground without damaging the device. If the input is left open-circuit or grounded, the output can be pulled below ground by 20V. For fixed voltage versions, the output will act like a large resistor, typically 500k or higher, limiting current flow to less than 100A. For adjustable versions, the output will act like an open circuit; no current will flow out of the pin. If the input is powered by a voltage source, the output will source the short-circuit current of the device and will protect itself by thermal limiting. In this case, grounding the SHDN pin will turn off the device and stop the output from sourcing the short-circuit current. 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. 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 20V.
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* Device is mounted on topside
Calculating Junction Temperature Example: Given an output voltage of 3.3V, an input voltage range of 4V to 6V, an output current range of 0mA to 250mA 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) = 250mA VIN(MAX) = 6V IGND at (IOUT = 250mA, VIN = 6V) = 5mA So, P = 250mA(6V - 3.3V) + 5mA(6V) = 0.71W The thermal resistance will be in the range of 60C/W to 86C/W, depending on the copper area. So, the junction temperature rise above ambient will be approximately equal to: 0.71W(75C/W) = 53.3C The maximum junction temperature will then be equal to the maximum junction temperature rise above ambient plus the maximum ambient temperature, or : TJMAX = 50C + 53.3C = 103.3C
17
LT1763 Series APPLICATIONS INFORMATION
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 13V difference between output and ADJ pin divided by the 5mA maximum current into the ADJ pin yields a minimum top resistor value of 2.6k. 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 open-circuit. Current flow back into the output will follow the curve shown in Figure 7.
100 REVERSE OUTPUT CURRENT (A) TJ = 25C 90 VIN = 0V CURRENT FLOWS 80 INTO OUTPUT PIN 70 VOUT = VADJ (LT1763) LT1763 60 LT1763-1.8 50 LT1763-2.5 40 30 20 10 0 0 1 2 LT1763-5 LT1763-3.3 345678 OUTPUT VOLTAGE (V) 9 10
1763 F07
When the IN pin of the LT1763-X 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 device 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.
LT1763-1.5
LT1763-3
Figure 7. Reverse Output Current
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18
LT1763 Series PACKAGE DESCRIPTION
DE/UE Package 12-Lead Plastic DFN (4mm x 3mm)
(Reference LTC DWG # 05-08-1695 Rev D)
4.00 0.10 (2 SIDES) 0.70 0.05 3.30 0.05 1.70 0.05 PACKAGE OUTLINE 0.25 0.05 0.50 BSC 2.50 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 0.00 - 0.05 0.200 REF 0.75 0.05 PIN 1 TOP MARK (NOTE 6) 3.00 0.10 (2 SIDES) R = 0.05 TYP
7
R = 0.115 TYP
0.40 12
0.10
3.60 0.05 2.20 0.05
3.30 0.10 1.70 0.10 PIN 1 NOTCH R = 0.20 OR 0.35 45 CHAMFER 6 0.25 1 0.05 0.50 BSC 2.50 REF BOTTOM VIEW--EXPOSED PAD
(UE12/DE12) DFN 0806 REV D
NOTE: 1. DRAWING PROPOSED TO BE A VARIATION OF VERSION 5. EXPOSED PAD SHALL BE SOLDER PLATED (WGED) IN JEDEC PACKAGE OUTLINE M0-229 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION 2. DRAWING NOT TO SCALE ON THE TOP AND BOTTOM OF PACKAGE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.045 .005 .050 BSC 8
.189 - .197 (4.801 - 5.004) NOTE 3 7 6 5 .053 - .069 (1.346 - 1.752)
.004 - .010 (0.101 - 0.254)
.245 MIN
.160 .005
.228 - .244 (5.791 - 6.197)
.150 - .157 (3.810 - 3.988) NOTE 3
.014 - .019 (0.355 - 0.483) TYP .010 - .020 45 (0.254 - 0.508)
.008 - .010 (0.203 - 0.254)
.050 (1.270) BSC
.030 .005 TYP RECOMMENDED SOLDER PAD LAYOUT
NOTE: 1. DIMENSIONS IN
1
2
3
4
0- 8 TYP
INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
.016 - .050 (0.406 - 1.270)
SO8 0303
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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.
19
LT1763 Series TYPICAL APPLICATION
Paralleling of Regulators for Higher Output Current
R1 0.1 3.3V 1A C2 10F
+
VIN > 3.8V
IN C1 10F
OUT SENSE LT1763-3.3
+
C4 0.01F
SHDN BYP GND R2 0.1 IN LT1763 SHDN R3 2.2k R4 2.2k 3 SHDN GND BYP ADJ OUT
C5 0.01F
R6 2k R7 1.21k
+ -
8 1
R5 10k
1/2 LT1490 2 4
C3 0.01F
1763 TA03
RELATED PARTS
PART NUMBER LT1120 LT1121 LT1129 LT1175 LT1521 LT1529 LT1613 LT1761 Series LT1762 Series LT1764A LT1962 LT1963A LT3010 LT3021 DESCRIPTION 125mA Low Dropout Regulator with 20A IQ 150mA Micropower Low Dropout Regulator 700mA Micropower Low Dropout Regulator 500mA Negative Low Dropout Micropower Regulator 300mA Low Dropout Micropower Regulator with Shutdown 3A Low Dropout Regulator with 50A IQ 1.4MHz Single-Cell Micropower DC/DC Converter 100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 150mA, Low Noise, LDO Micropower Regulators 3A, Fast Transient Response Low Dropout Regulator 300mA, Fast Transient Response Low Dropout Regulator 1.5A, Fast Transient Response Low Dropout Regulator 50mA, 80V Low Noise, LDO Micropower Regulator 500mA, Low Voltage, Very Low Dropout Linear Regulator COMMENTS Includes 2.5V Reference and Comparator 30A IQ , SOT-223 Package 50A Quiescent Current 45A IQ , 0.26V Dropout Voltage, SOT-223 Package 15A IQ , Reverse Battery Protection 500mV Dropout Voltage SOT-23 Package, Internally Compensated 20A Quiescent Current, 20VRMS Noise, ThinSOTTM 25A Quiescent Current, 20VRMS Noise, MS8 340mV Dropout Voltage, DD, TO220 270mV Dropout Voltage, 20VRML , MS8 340mV Dropout Voltage, 40VRML , DD, TO220, S8, SOT-223 300mV Dropout Voltage, MS8E 160mV Dropout Voltage, DFN-8 and SOIC-8 Packages
ThinSOT is a trademark of Linear Technology Corporation.
1763fe
20 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 1008 REV E * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 1999

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