LT1963AES8-2.5#PBF [Linear]

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LT1963AES8-2.5#PBF
型号: LT1963AES8-2.5#PBF
厂家: Linear    Linear
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LT1963A Series  
1.5A, Low Noise,  
Fast Transient Response  
LDO Regulators  
U
FEATURES  
DESCRIPTIO  
The LT®1963A series are low dropout regulators opti-  
mized for fast transient response. The devices are capable  
of supplying 1.5A of output current with a dropout voltage  
of 340mV. Operating quiescent current is 1mA, dropping  
to<1mAinshutdown. Quiescentcurrentiswellcontrolled;  
it does not rise in dropout as it does with many other  
regulators. In addition to fast transient response, the  
LT1963A regulators have very low output noise which  
makes them ideal for sensitive RF supply applications.  
Optimized for Fast Transient Response  
Output Current: 1.5A  
Dropout Voltage: 340mV  
Low Noise: 40mVRMS (10Hz to 100kHz)  
1mA Quiescent Current  
No Protection Diodes Needed  
Controlled Quiescent Current in Dropout  
Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3.3V  
Adjustable Output from 1.21V to 20V  
<1mA Quiescent Current in Shutdown  
Stable with 10mF Output Capacitor  
Stable with Ceramic Capacitors  
Reverse Battery Protection  
Output voltage range is from 1.21V to 20V. The LT1963A  
regulators are stable with output capacitors as low as  
10mF. 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 devices are available in  
fixed output voltages of 1.5V, 1.8V, 2.5V, 3.3V and as an  
adjustable device with a 1.21V reference voltage. The  
LT1963A regulators are available in 5-lead TO-220, DD,  
3-lead SOT-223 and 8-lead SO packages.  
No Reverse Current  
Thermal Limiting  
U
APPLICATIO S  
3.3V to 2.5V Logic Power Supplies  
Post Regulator for Switching Supplies  
, LTC and LT are registered trademarks of Linear Technology Corporation.  
U
TYPICAL APPLICATION  
Dropout Voltage  
400  
3.3V to 2.5V Regulator  
350  
300  
250  
200  
150  
100  
50  
2.5V  
1.5A  
10µF*  
IN  
OUT  
+
+
V
> 3V  
10µF*  
IN  
LT1963A-2.5  
SHDN SENSE  
GND  
*TANTALUM,  
CERAMIC OR  
ALUMINUM ELECTROLYTIC  
1963 TA01  
0
0.8 1.0  
0
0.2 0.4 0.6  
1.2 1.4 1.6  
OUTPUT CURRENT (A)  
1963 TA02  
1963af  
1
LT1963A Series  
W W  
U W  
ABSOLUTE AXI U RATI GS (Note 1)  
SHDN Pin Voltage................................................. ±20V  
Output Short-Circuit Duration......................... Indefinite  
Operating Junction Temperature Range 45C to 125C  
Storage Temperature Range ................. 65C to 150C  
Lead Temperature (Soldering, 10 sec).................. 300C  
IN Pin Voltage........................................................ ±20V  
OUT Pin Voltage .................................................... ±20V  
Input to Output Differential Voltage (Note 2) ......... ±20V  
SENSE Pin Voltage ............................................... ±20V  
ADJ Pin Voltage ...................................................... ±7V  
U W  
U
PACKAGE/ORDER I FOR ATIO  
FRONT VIEW  
FRONT VIEW  
ORDER PART  
NUMBER  
ORDER PART  
5
4
3
2
1
SENSE/ADJ*  
OUT  
5
4
3
2
1
SENSE/ADJ*  
OUT  
NUMBER  
TAB IS  
GND  
GND  
GND  
LT1963AET  
LT1963AEQ  
IN  
IN  
LT1963AET-1.5  
LT1963AET-1.8  
LT1963AET-2.5  
LT1963AET-3.3  
LT1963AEQ-1.5  
LT1963AEQ-1.8  
LT1963AEQ-2.5  
LT1963AEQ-3.3  
SHDN  
SHDN  
TAB IS  
GND  
T PACKAGE  
5-LEAD PLASTIC TO-220  
Q PACKAGE  
5-LEAD PLASTIC DD  
*PIN 5 = SENSE FOR LT1963A-1.8/LT1963A-2.5/LT1963A-3.3  
= ADJ FOR LT1963A  
*PIN 5 = SENSE FOR LT1963A-1.8/LT1963A-2.5/LT1963A-3.3  
= ADJ FOR LT1963A  
TJMAX = 150C, qJA = 50C/ W  
TJMAX = 150C, qJA = 30C/ W  
ORDER PART  
NUMBER  
ORDER PART  
NUMBER  
TOP VIEW  
LT1963AEST-1.5  
LT1963AEST-1.8  
LT1963AEST-2.5  
LT1963AEST-3.3  
LT1963AES8  
FRONT VIEW  
OUT  
SENSE/ADJ*  
GND  
1
2
3
4
8
7
6
5
IN  
LT1963AES8-1.5  
LT1963AES8-1.8  
LT1963AES8-2.5  
LT1963AES8-3.3  
3
2
1
OUT  
GND  
IN  
GND  
GND  
SHDN  
TAB IS  
GND  
NC  
S8 PACKAGE  
8-LEAD PLASTIC SO  
ST PACKAGE  
3-LEAD PLASTIC SOT-223  
ST PART  
MARKING  
S8 PART  
MARKING  
*PIN 2 = SENSE FOR LT1963A-1.8/LT1963A-2.5/LT1963A-3.3  
= ADJ FOR LT1963A  
TJMAX = 150C, qJA = 50C/ W  
TJMAX = 150C, qJA = 70C/ W  
1963A  
963A15  
963A18  
963A25  
963A33  
963A15  
963A18  
963A25  
963A33  
Consult LTC Marketing for parts specified with wider operating temperature ranges.  
1963af  
2
LT1963A Series  
ELECTRICAL CHARACTERISTICS  
The denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25C. (Note 2)  
PARAMETER  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
Minimum Input Voltage (Notes 4,12)  
I
I
= 0.5A  
= 1.5A  
1.9  
2.1  
V
V
LOAD  
LOAD  
2.5  
Regulated Output Voltage (Note 5)  
LT1963A-1.5  
LT1963A-1.8  
LT1963A-2.5  
LT1963A-3.3  
LT1963A  
V
= 2.21V, I  
= 1mA  
1.477  
1.447  
1.500  
1.500  
1.523  
1.545  
V
V
IN  
LOAD  
2.5V < V < 20V, 1mA < I  
< 1.5A  
< 1.5A  
< 1.5A  
< 1.5A  
< 1.5A  
IN  
LOAD  
LOAD  
LOAD  
LOAD  
LOAD  
V
= 2.3V, I  
= 1mA  
LOAD  
1.773  
1.737  
1.800  
1.800  
1.827  
1.854  
V
V
IN  
2.8V < V < 20V, 1mA < I  
IN  
V
= 3V, I  
= 1mA  
2.462  
2.412  
2.500  
2.500  
2.538  
2.575  
V
V
IN  
LOAD  
3.5V < V < 20V, 1mA < I  
IN  
V
= 3.8V, I  
= 1mA  
LOAD  
3.250  
3.200  
3.300  
3.300  
3.350  
3.400  
V
V
IN  
4.3V < V < 20V, 1mA < I  
IN  
ADJ Pin Voltage  
(Notes 4, 5)  
V
= 2.21V, I  
= 1mA  
1.192  
1.174  
1.210  
1.210  
1.228  
1.246  
V
V
IN  
LOAD  
2.5V < V < 20V, 1mA < I  
IN  
Line Regulation  
LT1963A-1.5  
LT1963A-1.8  
LT1963A-2.5  
LT1963A-3.3  
DV = 2.21V to 20V, I  
= 1mA  
2.0  
2.5  
3.0  
3.5  
1.5  
6
7
10  
10  
5
mV  
mV  
mV  
mV  
mV  
IN  
LOAD  
DV = 2.3V to 20V, I  
= 1mA  
IN  
IN  
LOAD  
LOAD  
LOAD  
DV = 3V to 20V, I  
= 1mA  
= 1mA  
= 1mA  
DV = 3.8V to 20V, I  
IN  
LT1963A (Note 4) DV = 2.21V to 20V, I  
IN  
LOAD  
Load Regulation  
LT1963A-1.5  
LT1963A-1.8  
LT1963A-2.5  
LT1963A-3.3  
LT1963A (Note 4)  
V
V
= 2.5V, DI  
= 2.5V, DI  
= 1mA to 1.5A  
= 1mA to 1.5A  
2
9
mV  
mV  
IN  
IN  
LOAD  
LOAD  
18  
V
V
= 2.8V, DI  
= 2.8V, DI  
= 1mA to 1.5A  
= 1mA to 1.5A  
2
10  
20  
mV  
mV  
IN  
IN  
LOAD  
LOAD  
V
V
= 3.5V, DI  
= 3.5V, DI  
= 1mA to 1.5A  
= 1mA to 1.5A  
2.5  
3
15  
30  
mV  
mV  
IN  
IN  
LOAD  
LOAD  
V
V
= 4.3V, DI  
= 4.3V, DI  
= 1mA to 1.5A  
= 1mA to 1.5A  
20  
35  
mV  
mV  
IN  
IN  
LOAD  
LOAD  
V
V
= 2.5V, DI  
= 2.5V, DI  
= 1mA to 1.5A  
= 1mA to 1.5A  
2
8
15  
mV  
mV  
IN  
IN  
LOAD  
LOAD  
Dropout Voltage  
I
I
= 1mA  
= 1mA  
0.02  
0.10  
0.19  
0.34  
0.06  
0.10  
V
V
LOAD  
LOAD  
V
= V  
IN  
OUT(NOMINAL)  
(Notes 6, 7, 12)  
I
I
= 100mA  
= 100mA  
0.17  
0.22  
V
V
LOAD  
LOAD  
I
I
= 500mA  
= 500mA  
0.27  
0.35  
V
V
LOAD  
LOAD  
I
I
= 1.5A  
= 1.5A  
0.45  
0.55  
V
V
LOAD  
LOAD  
GND Pin Current  
IN  
(Notes 6, 8)  
I
I
I
I
I
= 0mA  
1.0  
1.1  
3.8  
15  
1.5  
1.6  
5.5  
25  
mA  
mA  
mA  
mA  
mA  
LOAD  
LOAD  
LOAD  
LOAD  
LOAD  
V
= V  
+ 1V  
OUT(NOMINAL)  
= 1mA  
= 100mA  
= 500mA  
= 1.5A  
80  
120  
Output Voltage Noise  
ADJ Pin Bias Current  
Shutdown Threshold  
C
= 10mF, I  
= 1.5A, BW = 10Hz to 100kHz  
40  
3
mV  
RMS  
OUT  
LOAD  
(Notes 4, 9)  
10  
2
mA  
V
V
V
V
= Off to On  
= On to Off  
0.90  
0.75  
OUT  
OUT  
0.25  
SHDN Pin Current  
(Note 10)  
V
V
= 0V  
= 20V  
0.01  
3
1
30  
mA  
mA  
SHDN  
SHDN  
Quiescent Current in Shutdown  
Ripple Rejection  
V
= 6V, V  
= 0V  
SHDN  
0.01  
63  
1
mA  
dB  
IN  
V
– V  
= 1.5V (Avg), V  
= 0.5V ,  
P-P  
55  
IN  
OUT  
= 120Hz, I  
RIPPLE  
f
= 0.75A  
RIPPLE  
LOAD  
Current Limit  
V
V
= 7V, V  
= 0V  
2
A
A
IN  
IN  
OUT  
= V  
+ 1V, DV  
= 0.1V  
1.6  
OUT(NOMINAL)  
OUT  
1963af  
3
LT1963A Series  
ELECTRICAL CHARACTERISTICS  
The denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25C. (Note 2)  
PARAMETER  
CONDITIONS  
MIN  
TYP  
MAX  
UNITS  
Input Reverse Leakage Current (Note 13) Q, T, S8 Packages  
ST Package  
V
V
= 20V, V  
= 20V, V  
= 0V  
= 0V  
1
2
mA  
mA  
IN  
IN  
OUT  
OUT  
Reverse Output Current (Note 11)  
LT1963A-1.5  
LT1963A-1.8  
LT1963A-2.5  
LT1963A-3.3  
LT1963A (Note 4)  
V
V
V
V
V
= 1.5V, V < 1.5V  
600  
600  
600  
600  
300  
1200  
1200  
1200  
1200  
600  
mA  
mA  
mA  
mA  
mA  
OUT  
OUT  
OUT  
OUT  
OUT  
IN  
= 1.8V, V < 1.8V  
IN  
= 2.5V, V < 2.5V  
IN  
= 3.3V, V < 3.3V  
IN  
= 1.21V, V < 1.21V  
IN  
Note 1: Absolute Maximum Ratings are those values beyond which the life  
of a device may be impaired.  
external resistor divider (two 4.12k resistors) for an output voltage of  
2.4V. The external resistor divider will add a 300mA DC load on the output.  
Note 2: Absolute maximum input to output differential voltage can not be  
achieved with all combinations of rated IN pin and OUT pin voltages. With  
the IN pin at 20V, the OUT pin may not be pulled below 0V. The total  
measured voltage from IN to OUT can not exceed ±20V.  
Note 7: 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: V – V  
.
IN  
DROPOUT  
Note 8: GND pin current is tested with V = V  
+ 1V and a  
IN  
OUT(NOMINAL)  
Note 3: The LT1963A regulators are tested and specified under pulse load  
current source load. The GND pin current will decrease at higher input  
voltages.  
conditions such that T ª T . The LT1963A is 100% tested at  
J
A
T = 25C. Performance at 40C and 125C is assured by design,  
A
Note 9: ADJ pin bias current flows into the ADJ pin.  
Note 10: SHDN pin current flows into the SHDN pin.  
Note 11: 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 12. For the LT1963A, LT1963A-1.5 and LT1963A-1.8 dropout voltage  
will be limited by the minimum input voltage specification under some  
output voltage/load conditions.  
Note 13. For the ST package, the input reverse leakage current increases  
due to the additional reverse leakage current for the SHDN pin, which is  
tied internally to the IN pin.  
characterization and correlation with statistical process controls.  
Note 4: The LT1963A (adjustable version) is tested and specified for these  
conditions with the ADJ pin connected to the OUT pin.  
Note 5: 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 6: To satisfy requirements for minimum input voltage, the LT1963A  
(adjustable version) is tested and specified for these conditions with an  
U W  
TYPICAL PERFOR A CE CHARACTERISTICS  
Typical Dropout Voltage  
Guaranteed Dropout Voltage  
Dropout Voltage  
500  
450  
400  
350  
300  
250  
200  
150  
100  
50  
500  
450  
400  
350  
300  
250  
200  
150  
100  
50  
600  
500  
400  
300  
200  
100  
0
TEST POINTS  
T
125°C  
J
T
= 125°C  
J
I
= 1.5A  
L
T
25°C  
J
T
= 25°C  
I
= 0.5A  
J
L
I
= 100mA  
L
I
= 1mA  
L
0
0
0
0.8  
1.2 1.4  
0
0.8  
1.2 1.4  
0.2 0.4 0.6  
1.0  
1.6  
0.2 0.4 0.6  
1.0  
1.6  
–50  
0
25  
50  
75 100 125  
–25  
OUTPUT CURRENT (A)  
OUTPUT CURRENT (A)  
TEMPERATURE (°C)  
1963 • G01  
1963 • G02  
1963 G03  
1963af  
4
LT1963A Series  
U W  
TYPICAL PERFOR A CE CHARACTERISTICS  
Quiescent Current  
LT1963A-1.8 Output Voltage  
LT1963A-1.5 Output Voltage  
1.84  
1.83  
1.82  
1.81  
1.80  
1.79  
1.78  
1.77  
1.76  
1.4  
1.2  
1.0  
0.8  
0.6  
0.4  
0.2  
0
1.54  
I
= 1mA  
I
= 1mA  
L
L
1.53  
1.52  
LT1963A-1.5/1.8/-2.5/-3.3  
1.51  
1.50  
1.49  
1.48  
1.47  
LT1963A  
V
= 6V  
IN  
L
R
= , I = 0  
L
V
= V  
SHDN  
IN  
1.46  
–25  
0
25  
50  
75  
125  
–50  
100  
50  
TEMPERATURE (°C)  
100 125  
50 25  
0
25  
75  
25  
0
50  
75 100 125  
50  
25  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
1963 G05  
1963 G04  
1963 G40  
LT1963A-2.5 Output Voltage  
LT1963A-3.3 Output Voltage  
LT1963A ADJ Pin Voltage  
1.230  
1.225  
1.220  
1.215  
1.210  
1.205  
1.200  
1.195  
1.190  
2.58  
2.56  
2.54  
2.52  
2.50  
2.48  
2.46  
2.44  
2.42  
3.38  
3.36  
3.34  
3.32  
3.30  
3.28  
3.26  
3.24  
3.22  
I
= 1mA  
I
= 1mA  
I = 1mA  
L
L
L
–25  
0
25  
50  
75  
125  
–50  
100  
–25  
0
25  
50  
75  
125  
–50  
–25  
0
25  
50  
75  
100  
125  
–50  
100  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
1963 G08  
1963 G06  
1963 G07  
LT1963A-2.5 Quiescent Current  
LT1963A-1.5 Quiescent Current  
LT1963A-1.8 Quiescent Current  
14  
12  
14  
12  
10  
8
14  
12  
10  
8
T
R
V
= 25°C  
= ∞  
SHDN  
T
R
V
= 25°C  
=  
SHDN  
J
L
T
R
V
= 25°C  
= ∞  
SHDN  
J
L
J
L
= V  
= V  
IN  
= V  
IN  
IN  
10  
8
6
4
2
6
6
4
4
2
2
0
0
0
0
3
5
6
7
8
9
10  
5
6
7
8
9
10  
1
2
4
0
5
6
7
8
9
10  
0
3
4
1
2
3
4
1
2
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
1963 G41  
1963 G10  
1963 G09  
1963af  
5
LT1963A Series  
TYPICAL PERFOR A CE CHARACTERISTICS  
U W  
LT1963A Quiescent Current  
LT1963A-1.5 GND Pin Current  
LT1963A-3.3 Quiescent Current  
25  
20  
15  
14  
12  
10  
8
14  
12  
10  
8
T = 25°C  
J
T
R
V
= 25°C  
T
R
V
= 25°C  
= ∞  
SHDN  
J
L
J
L
V
= V  
= 4.3k  
SHDN  
IN  
*FOR V  
= 1.5V  
= V  
= V  
OUT  
SHDN  
IN  
IN  
R
= 150, I = 10mA*  
L
L
6
6
R
L
= 5, I = 300mA*  
L
10  
5
4
4
R
= 15, I = 100mA*  
L
L
2
2
0
0
0
0
6
8
10 12 14 16 18 20  
0
1
2
3
6
7
8
9
2
4
4
5
10  
0
3
4
5
6
7
8
9
10  
1
2
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
1963 G12  
1963 G42  
1963 G11  
LT1963A-1.8 GND Pin Current  
LT1963A-2.5 GND Pin Current  
LT1963A-3.3 GND Pin Current  
25  
20  
15  
10  
5
25  
20  
15  
10  
5
25  
20  
15  
10  
5
T
= 25°C  
SHDN  
T
V
= 25°C  
J
SHDN  
T
= 25°C  
SHDN  
J
J
V
= V  
= V  
V
= V  
IN  
IN  
IN  
*FOR V  
= 1.8V  
*FOR V  
= 2.5V  
OUT  
*FOR V  
= 3.3V  
OUT  
OUT  
R
= 8.33, I = 300mA*  
L
L
R
= 11, I = 300mA*  
L
L
R
L
= 6, I = 300mA*  
L
R
= 25, I = 100mA*  
L
L
R
= 33, I = 100mA*  
L
L
R
L
= 18, I = 100mA*  
L
R
2
= 180, I = 10mA*  
L
L
R
= 250, I = 10mA*  
L
L
R
3
= 330, I = 100mA*  
L L  
0
0
0
0
1
2
3
4
5
6
7
8
9
10  
0
1
3
4
5
6
7
8
9
10  
0
1
4
5
6
7
8
9
10  
2
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
1963 G14  
1963 G13  
1963 G15  
LT1963A GND Pin Current  
LT1963A-1.5 GND Pin Current  
LT1963A-1.8 GND Pin Current  
10  
8
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
T
= 25°C  
T
= 25°C  
SHDN  
T = 25°C  
J
J
J
V
= V  
V
= V  
V
= V  
IN  
SHDN  
*FOR V  
IN  
IN  
= 1.5V  
SHDN  
*FOR V  
*FOR V  
= 1.21V  
OUT  
= 1.8V  
OUT  
OUT  
R
L
= 4.33, I = 300mA*  
L
6
R = 1.2, I = 1.5A*  
L L  
R
= 1, I = 1.5A*  
L
L
R
= 1.5, I = 1A*  
L
L
4
R
L
= 12.1, I = 100mA*  
L
R
L
= 1.8, I = 1A*  
L
R
= 3, I = 500mA*  
L
L
2
R
L
= 121, I = 10mA*  
L
R
L
= 3.6, I = 500mA*  
L
0
0
1
2
3
4
5
6
7
8
9
10  
4
0
1
2
3
5
6
7
8
9
10  
0
1
2
3
4
5
6
7
8
9
10  
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
1963 G16  
1963 G17  
1963 G43  
1963af  
6
LT1963A Series  
U W  
TYPICAL PERFOR A CE CHARACTERISTICS  
LT1963A-2.5 GND Pin Current  
LT1963A GND Pin Current  
LT1963A-3.3 GND Pin Current  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
T
= 25°C  
SHDN  
T = 25°C  
J
SHDN  
J
V
T
= 25°C  
SHDN  
J
V
= V  
V
= V  
IN  
= 3.3V  
= V  
IN  
IN  
= 2.5V  
*FOR V  
*FOR V = 1.21V  
OUT  
*FOR V  
OUT  
OUT  
R
= 2.2, I = 1.5A*  
L
R
= 1.67, I = 1.5A*  
L
L
L
R
= 0.81, I = 1.5A*  
L
L
R
= 2.5, I = 1A*  
L
L
R
= 3.3, I = 1A*  
L
L
R
= 1.21, I = 1A*  
L
L
R
= 5, I = 500mA*  
L
L
R
= 6.6, I = 500mA*  
L
R
= 2.42, I = 500mA*  
L
L
L
4
4
0
1
2
3
5
6
7
8
9
10  
4
0
1
2
3
5
6
7
8
9
10  
0
1
2
3
5
6
7
8
9
10  
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
INPUT VOLTAGE (V)  
1963 G20  
1963 G19  
1963 G18  
GND Pin Current vs ILOAD  
SHDN Pin Threshold (Off-to-On)  
SHDN Pin Threshold (On-to-Off)  
1.0  
0.9  
0.8  
0.7  
0.6  
0.5  
0.4  
0.3  
0.2  
0.1  
0
1.0  
0.9  
0.8  
0.7  
0.6  
0.5  
0.4  
0.3  
0.2  
0.1  
0
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
0
I
= 1mA  
V
IN  
= V +1V  
OUT (NOMINAL)  
L
I
= 1.5A  
L
I
= 1mA  
L
50  
75 100 125  
–50  
0
25  
50  
75 100 125  
–50  
–25  
0
25  
–25  
0.8  
OUTPUT CURRENT (A)  
0
0.2 0.4 0.6  
1.0 1.2 1.4 1.6  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
1963 G23  
1963 G22  
1963 G21  
SHDN Pin Input Current  
SHDN Pin Input Current  
ADJ Pin Bias Current  
5.0  
4.5  
4.0  
3.5  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0
7
6
5
4
3
2
1
0
5.0  
4.5  
4.0  
3.5  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0
V
= 20V  
SHDN  
50  
100 125  
–50 –25  
0
25  
75  
–50  
0
25  
50  
75 100 125  
–25  
8
0
2
4
6
10 12 14 16 18 20  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
SHDN PIN VOLTAGE (V)  
1963 G25  
1963 G26  
1963 G24  
1963af  
7
LT1963A Series  
U W  
TYPICAL PERFOR A CE CHARACTERISTICS  
Current Limit  
Current Limit  
4.0  
3.5  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0
3.0  
V
V
= 7V  
IN  
OUT  
= 0V  
2.5  
T
J
= 25°C  
2.0  
1.5  
1.0  
0.5  
0
T
= 50°C  
J
T
J
= 125°C  
V  
= 100mV  
OUT  
4
0
2
6
8
10 12 14 16 18 20  
–50  
0
25  
50  
75  
125  
–25  
100  
INPUT/OUTPUT DIFFERENTIAL (V)  
TEMPERATURE (°C)  
1963 G27  
1963 G28  
Reverse Output Current  
Reverse Output Current  
1.0  
0.9  
0.8  
0.7  
0.6  
0.5  
0.4  
0.3  
0.2  
0.1  
0
5.0  
4.5  
4.0  
3.5  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0
V
V
V
V
V
V
= 0V  
IN  
= 1.21V (LT1963A)  
OUT  
OUT  
OUT  
OUT  
OUT  
LT1963A-1.8  
LT1963A-1.5  
= 1.5V (LT1963A-1.5)  
= 1.8V (LT1963A-1.8)  
= 2.5V (LT1963A-2.5)  
= 3.3V (LT1963A-3.3)  
LT1963A  
LT1963A-1.8/-2.5/-3.3  
LT1963A-3.3  
T = 25°C  
IN  
CURRENT FLOWS INTO  
OUTPUT PIN  
J
V
LT1963A  
= 0V  
LT1963A-2.5  
V
OUT  
V
OUT  
= V  
FB  
(LT1963A)  
ADJ  
= V (LT1963A-1.5/1.8/-2.5/-3.3)  
–50  
0
25  
50  
75 100 125  
4
–25  
0
1
2
3
5
6
7
8
9
10  
TEMPERATURE (°C)  
OUTPUT VOLTAGE (V)  
1963 G30  
1963 G29  
Ripple Rejection  
Ripple Rejection  
LT1963A Minimum Input Voltage  
80  
70  
60  
50  
40  
30  
20  
10  
0
76  
3.0  
74  
72  
70  
68  
66  
64  
62  
2.5  
2.0  
1.5  
1.0  
0.5  
0
I
= 1.5A  
L
I
= 500mA  
L
I
= 100mA  
L
C
= 100µF TANTALUM  
+10 1µF CERAMIC  
OUT  
C
= 10µF TANTALUM  
OUT  
I
= 0.75A  
L
I
= 0.75A  
L
V
= V  
+1V + 0.5V  
IN  
OUT(NOMINAL) P-P  
V
= V  
+1V + 50mV  
10k  
RIPPLE  
IN  
OUT(NOMINAL)  
RMS  
RIPPLE AT f = 120Hz  
50 25 25  
TEMPERATURE (°C)  
50  
100 125  
0
75  
10  
100  
1k  
100k  
1M  
50  
TEMPERATURE (°C)  
100 125  
–50 –25  
0
25  
75  
FREQUENCY (Hz)  
1963 G31  
1963 G32  
1963 G33  
1963af  
8
LT1963A Series  
U W  
TYPICAL PERFOR A CE CHARACTERISTICS  
Load Regulation  
Output Noise Spectral Density  
1.0  
0.1  
10  
C
L
= 10µF  
OUT  
=1.5A  
I
5
LT1963A-1.5  
0
–5  
LT1963A  
LT1963A-2.5  
LT1963A  
LT1963A-1.8  
LT1963A-2.5  
LT1963A-3.3  
LT1963A-3.3  
–10  
–15  
20  
V
V
= V  
+1V  
OUT(NOMINAL)  
IN  
LT1963A-1.8  
LT1963A-1.5  
(LT1963A-1.8/-2.5/-3.3)  
= 2.7V (LT1963A/LT1963A-1.5)  
IN  
L
I = 1mA TO 1.5A  
0.01  
50  
TEMPERATURE (°C)  
100 125  
–50 –25  
0
25  
75  
10  
100  
1k  
10k  
100k  
FREQUENCY (Hz)  
1963 G35  
1963 G34  
RMS Output Noise vs Load  
Current (10Hz to 100kHz)  
LT1963A-3.3 10Hz to 100kHz Output Noise  
50  
45  
40  
35  
30  
25  
20  
15  
10  
5
C
OUT  
= 10µF  
LT1963A-3.3  
LT1963A-2.5  
LT1963A-1.8  
V
OUT  
100µV/DIV  
LT1963A-1.5  
LT1963A  
0
1963 G37  
0.0001 0.001  
0.01  
0.1  
1
10  
C
LOAD  
= 10µF  
= 1.5A  
1ms/DIV  
OUT  
I
LOAD CURRENT (A)  
1063 G36  
LT1963A-3.3 Transient Response  
LT1963A-3.3 Transient Response  
200  
150  
100  
50  
150  
100  
50  
V
C
C
= 4.3V  
IN  
IN  
= 3.3µF TANTALUM  
= 10µF TANTALUM  
OUT  
0
0
–50  
–100  
–150  
1.5  
1.0  
0.5  
0
–50  
–100  
0.6  
0.4  
0.2  
0
V
C
C
= 4.3V  
IN  
IN  
= 33µF TANTALUM  
= 100µF TANTALUM  
OUT  
+10 1µF CERAMIC  
8
250  
300  
0
2
4
6
10 12 14 16 18 20  
0
50 100 150 200  
350 400 450 500  
TIME (µs)  
TIME (µs)  
1963 G38  
1963 G39  
1963af  
9
LT1963A Series  
U
U
U
PI FU CTIO S  
OUT: Output. The output supplies power to the load. A  
minimum output capacitor of 10mF 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.  
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 3mA. 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.  
SENSE: Sense. For fixed voltage versions of the LT1963A  
(LT1963A-1.5/LT1963A-1.8/LT1963A-2.5/LT1963A-3.3),  
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 resis-  
tance(RP)ofPCtracesbetweentheregulatorandtheload.  
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 exter-  
nal PC traces will add to the dropout voltage of the regu-  
lator. The SENSE pin bias current is 600mA at the nominal  
rated output voltage. The SENSE pin can be pulled below  
ground (as in a dual supply system where the regulator  
load is returned to a negative supply) and still allow the  
device to start and operate.  
IN: 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 1mF to 10mF is sufficient. The LT1963A  
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.  
ADJ: Adjust. For the adjustable LT1963A, this is the input  
totheerroramplifier.Thispinisinternallyclampedto±7V.  
It has a bias current of 3mA which flows into the pin. The  
ADJ pin voltage is 1.21V referenced to ground and the  
output voltage range is 1.21V to 20V.  
IN  
OUT  
LT1963A  
R
P
+
+
SHDN SENSE  
GND  
LOAD  
V
IN  
R
P
1963 F01  
SHDN: Shutdown. The SHDN pin is used to put the  
LT1963A regulators into a low power shutdown state. The  
Figure 1. Kelvin Sense Connection  
1963af  
10  
LT1963A Series  
W U U  
APPLICATIO S I FOR ATIO  
U
The adjustable device is tested and specified with the ADJ  
pin tied to the OUT pin for an output voltage of 1.21V.  
Specifications for output voltages greater than 1.21V will  
be proportional to the ratio of the desired output voltage to  
1.21V: VOUT/1.21V. For example, load regulation for an  
output current change of 1mA to 1.5A is 3mV typical at  
VOUT = 1.21V. At VOUT = 5V, load regulation is:  
The LT1963A series are 1.5A low dropout regulators op-  
timized for fast transient response. The devices are ca-  
pable of supplying 1.5A at a dropout voltage of 350mV.  
The low operating quiescent current (1mA) drops to less  
than 1mA in shutdown. In addition to the low quiescent  
current, the LT1963A regulators incorporate several pro-  
tection features which make them ideal for use in battery-  
powered systems. The devices are protected against both  
reverseinputandreverseoutputvoltages.Inbatterybackup  
applications where the output can be held up by a backup  
battery when the input is pulled to ground, the LT1963A-X  
actslikeithasadiodeinserieswithitsoutputandprevents  
reverse current flow. Additionally, in dual supply applica-  
tions 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.  
(5V/1.21V)(–3mV) = 12.4mV  
Output Capacitance and Transient Response  
The LT1963A 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 capaci-  
tors. A minimum output capacitor of 10mF with an ESR of  
3W orlessisrecommendedtopreventoscillations. Larger  
values of output capacitance can decrease the peak devia-  
tions and provide improved transient response for larger  
loadcurrentchanges.Bypasscapacitors,usedtodecouple  
individual components powered by the LT1963A, will  
increase the effective output capacitor value.  
Adjustable Operation  
The adjustable version of the LT1963A has an output  
voltage range of 1.21V to 20V. The output voltage is set by  
theratiooftwoexternalresistorsasshowninFigure2.The  
deviceservostheoutputtomaintainthevoltageatthe ADJ  
pin at 1.21V referenced to ground. The current in R1 is  
then equal to 1.21V/R1 and the current in R2 is the current  
in R1 plus the ADJ pin bias current. The ADJ pin bias  
current, 3mA 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 4.17k to  
minimize errors in the output voltage caused by the ADJ  
pinbiascurrent.Notethatinshutdowntheoutputisturned  
off and the divider current will be zero.  
Extra consideration must be given to the use of ceramic  
capacitors. Ceramic capacitors are manufactured with a  
variety of dielectrics, each with different behavior over  
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 tem-  
perature coefficients as shown in Figures 3 and 4. When  
used with a 5V regulator, a 10mF Y5V capacitor can exhibit  
20  
BOTH CAPACITORS ARE 16V,  
1210 CASE SIZE, 10µF  
0
IN  
OUT  
LT1963A  
ADJ  
V
OUT  
X5R  
+
V
R2  
R1  
IN  
–20  
–40  
GND  
1963 F02  
–60  
Y5V  
R2  
ˆ
˜
¯
R1  
Ê
Ë
–80  
VOUT = 1.21V 1+  
+ I  
R2  
(
ADJ)(  
)
Á
VADJ = 1.21V  
IADJ = 3mA AT 25C  
OUTPUT RANGE = 1.21V TO 20V  
–100  
0
8
12 14  
2
4
6
10  
16  
DC BIAS VOLTAGE (V)  
1963 F03  
Figure 2. Adjustable Operation  
Figure 3. Ceramic Capacitor DC Bias Characteristics  
1963af  
11  
LT1963A Series  
W U U  
U
APPLICATIO S I FOR ATIO  
40  
currents. With a high input voltage, a problem can occur  
wherein removal of an output short will not allow the  
output voltage to recover. Other regulators, such as the  
LT1085, also exhibit this phenomenon, so it is not unique  
to the LT1963A-X.  
20  
X5R  
0
–20  
–40  
The problem occurs with a heavy output load when the  
input voltage is high and the output voltage is low. Com-  
mon situations are immediately after the removal of a  
short-circuit or when the shutdown pin is pulled high after  
the input voltage has already been turned on. The load line  
for such a load may intersect the output current curve at  
two points. If this happens, there are two stable output  
operating points for the regulator. With this double inter-  
section, the input power supply may need to be cycled  
down to zero and brought up again to make the output  
recover.  
Y5V  
–60  
–80  
BOTH CAPACITORS ARE 16V,  
1210 CASE SIZE, 10µF  
–100  
50  
TEMPERATURE (°C)  
100 125  
–50 –25  
0
25  
75  
1963 F04  
Figure 4. Ceramic Capacitor Temperature Characteristics  
an effective value as low as 1mF to 2mF 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.  
Output Voltage Noise  
The LT1963A regulators have been designed to provide  
low output voltage noise over the 10Hz to 100kHz band-  
width while operating at full load. Output voltage noise is  
typically 40nV/÷Hz over this frequency bandwidth for the  
LT1963A (adjustable version). For higher output voltages  
(generated by using a resistor divider), the output voltage  
noise will be gained up accordingly. This results in RMS  
noise over the 10Hz to 100kHz bandwidth of 14mVRMS for  
the LT1963A increasing to 38mVRMS for the LT1963A-3.3.  
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 micro-  
phone works. For a ceramic capacitor the stress can be  
induced by vibrations in the system or thermal transients.  
Higher values of output voltage noise may be measured  
when care is not exercised with regards to circuit layout  
and testing. Crosstalk from nearby traces can induce  
unwanted noise onto the output of the LT1963A-X. Power  
supply ripple rejection must also be considered; the  
LT1963A regulators do not have unlimited power supply  
rejection and will pass a small portion of the input noise  
through to the output.  
Overload Recovery  
Like many IC power regulators, the LT1963A-X has safe  
operating area protection. The safe area protection de-  
creases the current limit as input-to-output voltage in-  
creases and keeps the power transistor inside a safe  
operating region for all values of input-to-output voltage.  
Theprotectionisdesignedtoprovidesomeoutputcurrent  
at all values of input-to-output voltage up to the device  
breakdown.  
Thermal Considerations  
Thepowerhandlingcapabilityofthedeviceislimitedbythe  
maximum rated junction temperature (125C). The power  
dissipated by the device is made up of two components:  
When power is first turned on, as the input voltage rises,  
the output follows the input, allowing the regulator to start  
up into very heavy loads. During the start-up, as the input  
voltage is rising, the input-to-output voltage differential is  
small, allowing the regulator to supply large output  
1. Output current multiplied by the input/output voltage  
differential: (IOUT)(VIN – VOUT), and  
1963af  
12  
LT1963A Series  
W U U  
APPLICATIO S I FOR ATIO  
2. GND pin current multiplied by the input voltage:  
(IGND)(VIN).  
U
Table 3. SOT-223 Package, 3-Lead SOT-223  
COPPER AREA  
TOPSIDE*  
THERMAL RESISTANCE  
BOARD AREA (JUNCTION-TO-AMBIENT)  
BACKSIDE  
2500mm2  
2500mm2  
2500mm2  
2500mm2  
1000mm2  
0mm2  
The GND pin current can be found using the GND Pin  
Current curves in the Typical Performance Characteris-  
tics. Power dissipation will be equal to the sum of the two  
components listed above.  
2500mm2  
1000mm2  
225mm2  
100mm2  
1000mm2  
1000mm2  
2500mm2  
2500mm2  
2500mm2  
2500mm2  
1000mm2  
1000mm2  
42C/W  
42C/W  
50C/W  
56C/W  
49C/W  
52C/W  
The LT1963A series regulators have internal thermal  
limiting designed to protect the device during overload  
conditions. For continuous normal conditions, the maxi-  
mum 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 ambi-  
ent. Additional heat sources mounted nearby must also  
be considered.  
*Device is mounted on topside.  
T Package, 5-Lead TO-220  
Thermal Resistance (Junction-to-Case) = 4C/W  
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  
500mA and a maximum ambient temperature of 50C,  
what will the maximum junction temperature be?  
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 gener-  
ated by power devices.  
The power dissipated by the device will be equal to:  
IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)  
)
The following tables list thermal resistance for several  
different board sizes and copper areas. All measurements  
were taken in still air on 1/16" FR-4 board with one ounce  
copper.  
where,  
IOUT(MAX) = 500mA  
VIN(MAX) = 6V  
IGND at (IOUT = 500mA, VIN = 6V) = 10mA  
Table 1. Q Package, 5-Lead DD  
COPPER AREA  
THERMAL RESISTANCE  
So,  
BOARD AREA (JUNCTION-TO-AMBIENT)  
TOPSIDE*  
BACKSIDE  
2500mm2  
2500mm2  
2500mm2  
P = 500mA(6V – 3.3V) + 10mA(6V) = 1.41W  
2500mm2  
1000mm2  
125mm2  
2500mm2  
2500mm2  
2500mm2  
23C/W  
25C/W  
33C/W  
Using a DD package, the thermal resistance will be in the  
range of 23C/W to 33C/W depending on the copper  
area. So the junction temperature rise above ambient will  
be approximately equal to:  
*Device is mounted on topside  
Table 2. SO-8 Package, 8-Lead SO  
COPPER AREA  
1.41W(28C/W) = 39.5C  
THERMAL RESISTANCE  
BOARD AREA (JUNCTION-TO-AMBIENT)  
TOPSIDE*  
2500mm2  
1000mm2  
225mm2  
BACKSIDE  
2500mm2  
2500mm2  
2500mm2  
2500mm2  
The maximum junction temperature will then be equal to  
the maximum junction temperature rise above ambient  
plus the maximum ambient temperature or:  
2500mm2  
2500mm2  
2500mm2  
2500mm2  
55C/W  
55C/W  
63C/W  
69C/W  
100mm2  
TJMAX = 50C + 39.5C = 89.5C  
*Device is mounted on topside.  
1963af  
13  
LT1963A Series  
W U U  
U
APPLICATIO S I FOR ATIO  
Protection Features  
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  
fromthe1.21Vreferencewhentheoutputisforcedto20V.  
The top resistor of the resistor divider must be chosen to  
limitthecurrentintotheADJpintolessthan5mAwhenthe  
ADJpinisat7V. The13VdifferencebetweenOUTandADJ  
pinsdividedbythe5mAmaximumcurrentintotheADJpin  
yields a minimum top resistor value of 2.6k.  
The LT1963A regulators incorporate several protection  
featureswhichmakethemidealforuseinbattery-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  
areintendedtoprotectthedeviceagainstcurrentoverload  
conditions at the output of the device. For normal opera-  
tion, the junction temperature should not exceed 125C.  
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 5.  
The input of the device will withstand reverse voltages of  
20V.Currentflowintothedevicewillbelimitedtolessthan  
1mA (typically less than 100mA) and no negative voltage  
will appear at the output. The device will protect both itself  
and the load. This provides protection against batteries  
that can be plugged in backward.  
When the IN pin of the LT1963A is forced below the OUT  
pin or the OUT pin is pulled above the IN pin, input current  
will typically drop to less than 2mA. 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.  
The output of the LT1963A can be pulled below ground  
withoutdamagingthedevice.Iftheinputisleftopencircuit  
or grounded, the output can be pulled below ground by  
20V. For fixed voltage versions, the output will act like a  
large resistor, typically 5k or higher, limiting current flow  
to typically less than 600mA. 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.  
5.0  
LT1963A  
V
= V  
4.5  
4.0  
3.5  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0
OUT  
ADJ  
LT1963A-1.5  
= V  
V
OUT  
FB  
LT1963A-1.8  
= V  
V
OUT  
FB  
LT1963A-2.5  
= V  
V
OUT  
FB  
LT1963A-3.3  
= V  
V
OUT  
FB  
The ADJ pin of the adjustable device can be pulled above  
or below ground by as much as 7V without damaging the  
device. Iftheinputisleftopencircuitorgrounded, theADJ  
pin will act like an open circuit when pulled below ground  
and like a large resistor (typically 5k) in series with a diode  
when pulled above ground.  
T
= 25°C  
IN  
J
V
= 0V  
CURRENT FLOWS  
INTO OUTPUT PIN  
0
1
2
3
4
5
6
7
8
9
10  
OUTPUT VOLTAGE (V)  
1963 F05  
Figure 5. Reverse Output Current  
In situations where the ADJ pin is connected to a resistor  
divider that would pull the ADJ pin above its 7V clamp  
1963af  
14  
LT1963A Series  
U
TYPICAL APPLICATIO S  
SCR Pre-Regulator Provides Efficiency Over Line Variations  
L1  
500µH  
LT1963A-3.3  
3.3V  
1.5A  
OUT  
IN  
OUT  
L2  
1N4148  
1k  
+
+
10VAC AT  
115V  
SHDN  
GND  
FB  
10000µF  
22µF  
IN  
90-140  
VAC  
34k*  
10VAC AT  
115V  
IN  
1N4002  
“SYNC”  
1N4002  
1N4002  
12.1k*  
+V  
2.4k  
C1A  
TO ALL “+V”  
POINTS  
200k  
+
1N4148  
+
1/2  
22µF  
750  
LT1018  
0.1µF  
+V  
C1B  
+
750Ω  
+V  
A1  
0.033µF  
1/2  
LT1018  
+
1N4148  
10k  
LT1006  
10k  
10k  
+V  
1µF  
+V  
L1 = COILTRONICS CTX500-2-52  
L2 = STANCOR P-8559  
* = 1% FILM RESISTOR  
= NTE5437  
LT1004  
1.2V  
1963 TA03  
1963af  
15  
LT1963A Series  
U
PACKAGE DESCRIPTIO  
Q Package  
5-Lead Plastic DD Pak  
(Reference LTC DWG # 05-08-1461)  
0.060  
(1.524)  
TYP  
0.390 – 0.415  
(9.906 – 10.541)  
0.060  
0.256  
0.165 – 0.180  
(4.191 – 4.572)  
(1.524)  
(6.502)  
0.045 – 0.055  
(1.143 – 1.397)  
15° TYP  
+0.008  
0.004  
–0.004  
0.060  
(1.524)  
0.183  
(4.648)  
0.059  
(1.499)  
TYP  
0.330 – 0.370  
(8.382 – 9.398)  
+0.203  
–0.102  
0.102  
(
)
0.095 – 0.115  
(2.413 – 2.921)  
0.075  
(1.905)  
0.067  
(1.70)  
BSC  
0.050 ± 0.012  
(1.270 ± 0.305)  
0.300  
(7.620)  
0.013 – 0.023  
(0.330 – 0.584)  
+0.012  
0.143  
–0.020  
0.028 – 0.038  
(0.711 – 0.965)  
+0.305  
BOTTOM VIEW OF DD PAK  
HATCHED AREA IS SOLDER PLATED  
COPPER HEAT SINK  
3.632  
Q(DD5) 1098  
(
)
–0.508  
1963af  
16  
LT1963A Series  
U
PACKAGE DESCRIPTIO  
S8 Package  
8-Lead Plastic Small Outline (Narrow .150 Inch)  
(Reference LTC DWG # 05-08-1610)  
0.189 – 0.197*  
(4.801 – 5.004)  
7
5
8
6
0.150 – 0.157**  
(3.810 – 3.988)  
0.228 – 0.244  
(5.791 – 6.197)  
1
3
4
2
0.010 – 0.020  
(0.254 – 0.508)  
¥ 45  
0.053 – 0.069  
(1.346 – 1.752)  
0.004 – 0.010  
(0.101 – 0.254)  
0.008 – 0.010  
(0.203 – 0.254)  
0°– 8° TYP  
0.016 – 0.050  
(0.406 – 1.270)  
0.050  
(1.270)  
BSC  
0.014 – 0.019  
(0.355 – 0.483)  
TYP  
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH  
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE  
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD  
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE  
SO8 1298  
1963af  
17  
LT1963A Series  
U
PACKAGE DESCRIPTIO  
ST Package  
3-Lead Plastic SOT-223  
(Reference LTC DWG # 05-08-1630)  
0.248 – 0.264  
(6.30 – 6.71)  
0.114 – 0.124  
(2.90 – 3.15)  
0.264 – 0.287  
(6.70 – 7.30)  
0.130 – 0.146  
(3.30 – 3.71)  
0.033 – 0.041  
(0.84 – 1.04)  
0.0905  
(2.30)  
NOM  
10° – 16°  
0.010 – 0.014  
(0.25 – 0.36)  
10°  
MAX  
0.071  
(1.80)  
MAX  
10° – 16°  
0.0008 – 0.0040  
(0.0203 – 0.1016)  
0.024 – 0.033  
(0.60 – 0.84)  
0.012  
(0.31)  
MIN  
0.181  
(4.60)  
NOM  
ST3 (SOT-233) 1298  
1963af  
18  
LT1963A Series  
U
PACKAGE DESCRIPTIO  
T Package  
5-Lead Plastic TO-220 (Standard)  
(Reference LTC DWG # 05-08-1421)  
0.165 – 0.180  
(4.191 – 4.572)  
0.147 – 0.155  
(3.734 – 3.937)  
DIA  
0.390 – 0.415  
(9.906 – 10.541)  
0.045 – 0.055  
(1.143 – 1.397)  
0.230 – 0.270  
(5.842 – 6.858)  
0.570 – 0.620  
(14.478 – 15.748)  
0.620  
(15.75)  
TYP  
0.460 – 0.500  
(11.684 – 12.700)  
0.330 – 0.370  
(8.382 – 9.398)  
0.700 – 0.728  
(17.78 – 18.491)  
0.095 – 0.115  
(2.413 – 2.921)  
SEATING PLANE  
0.152 – 0.202  
(3.861 – 5.131)  
0.155 – 0.195*  
(3.937 – 4.953)  
0.260 – 0.320  
(6.60 – 8.13)  
0.013 – 0.023  
(0.330 – 0.584)  
0.067  
BSC  
0.135 – 0.165  
(3.429 – 4.191)  
0.028 – 0.038  
(0.711 – 0.965)  
(1.70)  
* MEASURED AT THE SEATING PLANE  
T5 (TO-220) 0399  
1963af  
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 represen-  
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.  
19  
LT1963A Series  
U
TYPICAL APPLICATIO S  
Adjustable Current Source  
Paralleling of Regulators for Higher Output Current  
R1  
0.01  
R5  
LT1963A-3.3  
3.3V  
3A  
C2  
22µF  
LT1963A-1.8  
IN  
OUT  
0.01  
+
+
LOAD  
IN  
OUT  
C1  
100µF  
V
> 3.7V  
IN  
R1  
+
C1  
10µF  
1k  
SHDN  
GND  
FB  
V
IN  
> 2.7V  
SHDN  
GND  
FB  
LT1004-1.2  
R4  
R6  
R8  
100k  
R2  
80.6k  
C3  
1µF  
2.2k 2.2k  
R2  
0.01Ω  
LT1963A  
R3  
2k  
IN  
OUT  
R7  
470Ω  
R6  
2
3
8
6.65k  
+
SHDN  
SHDN  
GND  
FB  
1
1/2  
LT1366  
R7  
4.12k  
4
C2  
3.3µF  
NOTE: ADJUST R1 FOR  
1963 TA04  
0A TO 1.5A CONSTANT CURRENT  
R3  
2.2k  
R4  
2.2k  
R5  
1k  
3
2
8
+
1
1/2  
LT1366  
C3  
0.01µF  
4
1963 TA05  
RELATED PARTS  
PART NUMBER  
LT1120  
DESCRIPTION  
125mA Low Dropout Regulator with 20mA I  
COMMENTS  
Includes 2.5V Reference and Comparator  
Q
LT1121  
150mA Micropower Low Dropout Regulator  
700mA Micropower Low Dropout Regulator  
30mA I , SOT-223 Package  
Q
LT1129  
50mA Quiescent Current  
LT1175  
500mA Negative Low Dropout Micropower Regulator  
300mA Low Dropout Micropower Regulator with Shutdown  
3A Low Dropout Regulator with 50mA I  
45mA I , 0.26V Dropout Voltage, SOT-223 Package  
Q
LT1521  
15mA I , Reverse Battery Protection  
Q
LT1529  
500mV Dropout Voltage  
Q
LT1772  
Constant Frequency, Current Mode Step-Down DC/DC Controller  
High Efficiency Synchronous Step-Down Switching Regulator  
Up to 94% Efficiency, SOT-23 Package, 100% Duty Cycle  
Burst ModeTM Operation, Monolithic, 100% Duty Cycle  
LTC1627  
LT1761 Series  
LT1762 Series  
LT1763 Series  
LT1764A Series  
LT1962 Series  
LT1964  
100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 20mA Quiescent Current, 20mV  
Noise, ThinSOTTM Package  
RMS  
RMS  
RMS  
150mA, Low Noise, LDO Micropower Regulators  
500mA, Low Noise, LDO Micropower Regulators  
3A, Fast Transient Response Low Dropout Regulator  
300mA, Low Noise, LDO Micropower Regulator  
200mA, Low Noise, Negative LDO Micropower Regulator  
25mA Quiescent Current, 20mV  
30mA Quiescent Current, 20mV  
Noise, MSOP Package  
Noise, SO-8 Package  
Noise  
340mV Dropout Voltage, 40mV  
RMS  
RMS  
RMS  
30mA Quiescent Current, 20mV  
30mA Quiescent Current, 30mV  
Noise, MSOP Package  
Noise, ThinSOT Package  
Burst Mode is a registered trademark of Linear Technology Corporation.  
ThinSOT is a trademark of Linear Technology Corporation.  
1963af  
LT/TP 0602 2K • PRINTED IN USA  
LinearTechnology Corporation  
1630 McCarthy Blvd., Milpitas, CA 95035-7417  
20  
(408) 432-1900 FAX: (408) 434-0507 www.linear.com  
LINEAR TECHNOLOGY CORPORATION 2002  

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