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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 500mA, Low Voltage, Very Low Dropout Linear Regulator DESCRIPTION

L, LT, LTC and L are registered trademarks of Linear Technology Corporation. VLDO is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.

FEATURES
LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 500mA, Low Voltage, Very Low Dropout Linear Regulator DESCRIPTION
L, LT, LTC and L are registered trademarks of Linear Technology Corporation. VLDO is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
APPLICATIONS
Low Current Regulators Battery-Powered Systems Cellular Phones Pagers Wireless Modems
TYPICAL APPLICATION
Minimum Input Voltage
1.8V to 1.5V, 500mA VLDO Regulator
VIN 1.8V 3.3F IN SHDN OUT LT3021-1.5 SENSE 3.3F VOUT 1.5V 500mA
0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -50 -25 0 25 50 75 TEMPERATURE (°C) 100 125
3021 TA01
3021 TA02
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 ABSOLUTE MAXIMUM RATINGS
(Note 1)
Operating Junction Temperature Range (E, I Grade) (Notes 2, 3) ......................- 40°C to 125°C Storage Temperature Range DH ...........................- 65°C to 125°C S8 ...........................- 65°C to 150°C Lead Temperature (Soldering, 10 sec, S8) ...... 300°C
PIN CONFIGURATION
TOP VIEW NC NC OUT OUT NC NC ADJ AGND 1 2 3 4 5 6 7 8 17 16 NC 15 NC 14 IN 13 NC 12 IN 11 NC 10 PGND 9 SHDN NC NC OUT OUT NC NC SENSE AGND 1 2 3 4 5 6 7 8 17 TOP VIEW 16 NC 15 NC 14 IN 13 NC 12 IN 11 NC 10 PGND 9 SHDN
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 ORDER INFORMAITON
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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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 ELECTRICAL CHARACTERISTICS
MIN TYP 0.9 0.9 196 193 1.176 1.157 1.470 1.447 1.764 1.737 -1.75 -10.5 -13 -15.8 -2 -6 -7.5 -9
Load Regulation (Note 6)
Dropout Voltage (Notes 7, 12)
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 ELECTRICAL CHARACTERISTICS
TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage
250 225 DROPOUT VOLTAGE (mV) 200 175 150 125 100 75 50 25 0 0 100 200 300 400 OUTPUT CURRENT (mA) 500
3021 G01
Dropout Voltage
Minimum Input Voltage
0 25 50 75 TEMPERATURE (°C)
3021 G02
3021 G16
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 TYPICAL PERFORMANCE CHARACTERISTICS
ADJ Pin Voltage
206 204 ADJ PIN VOLTAGE (mV) 202 200 198 196 194 -50 25
ADJ Pin Bias Current
Quiescent Current
ADJ PIN BIAS CURRENT (nA)
QUIESCENT CURRENT (A) -25 0 25 50 75 TEMPERATURE (°C) 100 125
3021 G11
0 25 50 75 TEMPERATURE (°C)
3021 G04
3021 G05
Output Voltage
50 25 75 0 TEMPERATURE (°C)
3021 G28
3021 G23
3021 G22
Quiescent Current
QUIESCENT CURRENT (mA)
3 4 5 6 7 INPUT VOLTAGE (V)
3021 G03 3021 G26 3021 G27
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 TYPICAL PERFORMANCE CHARACTERISTICS
GND Pin Current
3021 G06 3021 G24 3021 G25
GND Pin Current vs ILOAD
10 9 SHDN PIN THRESHOLD (V) GND PIN CURRENT (mA) 8 7 6 5 4 3 2 1 0 0 100 200 300 400 LOAD CURRENT (mA) 500
3021 G07
SHDN Pin Threshold
SHDN Pin Input Current
3 4 5 6 7 8 SHDN PIN VOLTAGE (V)
3021 G08
3021 G09
SHDN Pin Input Current
Current Limit
Reverse Output Current
0 25 50 75 TEMPERATURE (°C)
3021 G10
3021 G12
3021 G13
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 TYPICAL PERFORMANCE CHARACTERISTICS
Input Ripple Rejection
3021 G14
3021 G15
3021 G17
No-Load Recovery Threshold
3021 G20
Output Noise Spectral Density
1k 10k FREQUENCY (Hz)
3021 G18
RMS Output Noise vs Load Current (10Hz to 100kHz)
Transient Response
0.1 1 10 LOAD CURRENT (mA)
3021 G19
3021 G21
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 PIN FUNCTIONS
(DH Package / S8 Package)
OUT (Pins 3, 4 / Pin 2): These pins supply power to the load. Use a minimum output capacitor of 3.3F to prevent oscillations. Applications with large load transients require larger output capacitors to limit peak voltage transients. See the Applications Information section for more information on output capacitance and reverse output characteristics. SENSE (Pin 7 / Pin 3, Fixed Voltage Device Only): This pin is the sense point for the internal resistor divider. It should be tied directly to the OUT pins for best results. ADJ (Pin 7 / Pin 3): This pin is the inverting terminal to the error amplifier. Its typical input bias current of 20nA flows out of the pin (see curve of ADJ Pin Bias Current vs Temperature in the Typical Performance Characteristics). The ADJ pin reference voltage is 200mV (referred to GND). AGND (Pin 8 / Pin 4): Ground. PGND (Pins 10, 17 / Pin 6): Ground. SHDN (Pin 9 / Pin 5): The SHDN pin puts the LT3021 into a low power state. Pulling the SHDN pin low turns the output off. Drive the SHDN pin with either logic or an open collector / drain device with a pull-up resistor. The pull-up resistor supplies the pull-up current to the open collector /
drain logic, normally several microamperes, and the SHDN pin current, typically 2.5A. If unused, connect the SHDN pin to VIN. The LT3021 does not function if the SHDN pin is not connected. IN (Pins 12, 14 / Pin 8): These pins supply power to the device. The LT3021 requires a bypass capacitor at IN if it is more than six inches away from the main input filter capacitor. The output impedance of a battery rises with frequency, so include a bypass capacitor in battery-powered circuits. A bypass capacitor in the range of 3.3F to 10F suffices. The LT3021 withstands reverse voltages on the IN pin with respect to ground and the OUT pin. In the case of a reversed input, which occurs if a battery is plugged in backwards, the LT3021 acts as if a diode is in series with its input. No reverse current flows into the LT3021 and no reverse voltage appears at the load. The device protects itself and the load. EXPOSED PAD (Pin 17, DH16 Package Only): Ground. Solder Pin 17 to the PCB ground. Connect directly to Pins 8, 10 for best performance. NC (Pins 1, 2, 5, 6, 11, 13, 15, 16 / Pins 1, 7): No Connect. No connect pins may be floated, tied to IN or tied to GND.
BLOCK DIAGRAM
SHDN (9 / 5) SHUTDOWN
(DH Package / S8 Package)
IN (12, 14 / 8) THERMAL SHUTDOWN R3 D1 Q3 CURRENT GAIN Q1
200mV BIAS CURRENT AND REFERENCE GENERATOR 212mV
NO-LOAD RECOVERY Q2 R2
NOTE: FOR LT3021 ADJUST PIN (7 / 3) IS CONNECTED TO THE ADJUST PIN, R1 AND R2 ARE EXTERNAL. FOR LT3021-1.X PIN (7 / 3) IS CONNECTED TO THE OUTPUT SENSE PIN, R1 AND R2 ARE INTERNAL.
ERROR AMP D2 25k FIXED VOUT 1.2V 1.5V 1.8V R1 R2 20k 100k 20k 130k 20k 160k
OUT (3, 4 / 2) OUT SENSE (7 / 3)
GND (8, 10, 17 / 4, 6)
3021 BD
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 APPLICATIONS INFORMATION
IN VIN LT3021 SHDN GND ADJ R1
3021 F01
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OUT R2
Figure 1. Adjustable Operation
Specifications for output voltages greater than 200mV are proportional to the ratio of desired output voltage to 200mV (VOUT / 200mV). For example, load regulation for an output current change of 1mA to 500mA is typically
LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 APPLICATIONS INFORMATION
3021 F04
BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10F
Figure 4. Noise Resulting from Tapping on a Ceramic Capacitor
3021 F02
Figure 2. Ceramic Capacitor DC Bias Characteristics
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3021 F03
Figure 3. Ceramic Capacitor Temperature Characteristics
LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 APPLICATIONS INFORMATION
The LT3021 regulator has internal thermal limiting (with hysteresis) designed to protect the device during overload conditions. For normal continuous conditions, do not exceed the maximum junction temperature rating of 125°C. Carefully consider all sources of thermal resistance from junction to ambient including other heat sources mounted in proximity to the LT3021. The underside of the LT3021 DH package has exposed metal (14mm2) from the lead frame to where the die is attached. This allows heat to directly transfer from the die junction to the printed circuit board metal to control maximum operating junction temperature. The dual-in-line pin arrangement allows metal to extend beyond the ends of the package on the topside (component side) of a PCB. Connect this metal to GND on the PCB. The multiple IN and OUT pins of the LT3021 also assist in spreading heat to the PCB. The LT3021 S8 package has Pin 4 fused with the lead frame. This also allows heat to transfer from the die to the printed circuit board metal, therefore reducing the thermal resistance. Copper board stiffeners and plated throughholes can also be used to spread the heat generated by power devices. The following tables list thermal resistance for several different board sizes and copper areas for two different packages. Measurements were taken in still air on 3 / 32" FR-4 board with one ounce copper.
Table 1. Measured Thermal Resistance For DH Package
COPPER AREA TOPSIDE BACKSIDE 2500mm2 900mm2 225mm2 100mm2 50mm2 2500mm2 2500mm2 2500mm2 2500mm2 2500mm2 BOARD AREA 2500mm2 2500mm2 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 30°C / W 35°C / W 50°C / W 55°C / W 65°C / W
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Table 2. Measured Thermal Resistance For S8 Package
COPPER AREA TOPSIDE BACKSIDE 2500mm2 1000mm2 225mm2 100mm2 50mm2 2500mm2 2500mm2 2500mm2 2500mm2 2500mm2 BOARD AREA 2500mm2 2500mm2 2500mm2 2500mm2 2500mm2 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 70°C / W 70°C / W 78°C / W 84°C / W 96°C / W
Device is mounted on topside.
LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 APPLICATIONS INFORMATION
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 APPLICATIONS INFORMATION
If the LT3021 is powered by a battery mounted in close proximity on the same circuit board, a 3.3F input capacitor is sufficient for stability. However, if the LT3021 is powered by a distant supply, use a larger value input capacitor following the guideline of roughly 1F (in addition to the 3.3F minimum) per 8 inches of wire length. As power supply output impedance may vary, the minimum input capacitance needed to stabilize the application may also vary. Extra capacitance may also be placed directly on the output of the power supply however, this will require an order of magnitude more capacitance as opposed to placing extra capacitance in close proximity to the LT3021. Furthermore, series resistance may be placed between the supply and the input of the LT3021 to stabilize the application as little as 0.1 to 0.5 will suffice.
PACKAGE DESCRIPTION
(Reference LTC DWG # 05-08-1709)
PIN 1 NOTCH
(DH16) DFN 0204
NOTE: 1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WJJD-1) IN JEDEC PACKAGE OUTLINE MO-229 2. DRAWING NOT TO SCALE 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 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
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LT3021 / LT3021-1.2 / LT3021-1.5 / LT3021-1.8 PACKAGE DESCRIPTION
S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 - .197 (4.801 - 5.004) NOTE 3 7 6 5
.245 MIN
.150 - .157 (3.810 - 3.988) NOTE 3
.016 - .050 (0.406 - 1.270) NOTE: 1. DIMENSIONS IN
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)
.014 - .019 (0.355 - 0.483) TYP
.050 (1.270) BSC
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.
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