LT1963AES8 Linear Technology, LT1963AES8 Datasheet - Page 19

• Manufacturer Part Number: LT1963AES8
• Description: IC LDO REG LOW NOISE 1.5A 8-SOIC
• Manufacturer: Linear Technology

Specifications of LT1963AES8

• Regulator Topology: Positive Adjustable
• Voltage - Output: 1.21 ~ 20 V
• Voltage - Input: 2.1 ~ 20 V
• Voltage - Dropout (typical): 0.34V @ 1.5A
• Number Of Regulators: 1
• Current - Output: 1.5A
• Current - Limit (min): 1.6A
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIONS INFORMATION
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.
Table 3. Q Package, 5-Lead DD
*Device is mounted on topside
Table 4. S0-8 Package, 8-Lead SO
*Device is mounted on topside
Table 5. SOT-223 Package, 3-Lead SOT-223
*Device is mounted on topside
T Package, 5-Lead TO-220
Thermal Resistance (Junction-to-Case) = 4°C/W
Calculating Junction Temperature
Example: Given an output voltage of 3.3V, an input volt-
age range of 4V to 6V, an output current range of 0mA
to 500mA and a maximum ambient temperature of 50°C,
what will the maximum junction temperature be?
TOPSIDE*
TOPSIDE*
TOPSIDE*
2500mm
1000mm
2500mm
1000mm
2500mm
1000mm
1000mm
1000mm
125mm
225mm
125mm
225mm
100mm
COPPER AREA
COPPER AREA
COPPER AREA
2
2
2
2
2
2
2
2
2
2
2
2
2
BACKSIDE
BACKSIDE
BACKSIDE
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
1000mm
0mm
2
2
2
2
2
2
2
2
2
2
2
2
2
BOARD AREA
BOARD AREA
BOARD AREA
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
2500mm
1000mm
1000mm
2
2
2
2
2
2
2
2
2
2
2
2
2
(JUNCTION-TO-AMBIENT)
(JUNCTION-TO-AMBIENT)
(JUNCTION-TO-AMBIENT)
THERMAL RESISTANCE
THERMAL RESISTANCE
THERMAL RESISTANCE
23°C/W
25°C/W
33°C/W
55°C/W
55°C/W
63°C/W
69°C/W
42°C/W
42°C/W
50°C/W
56°C/W
49°C/W
52°C/W
The power dissipated by the device will be equal to:
where,
So,
Using a DD package, the thermal resistance will be in the
range of 23°C/W to 33°C/W depending on the copper
area. So the junction temperature rise above ambient will
be approximately equal to:
The maximum junction temperature will then be equal to
the maximum junction temperature rise above ambient
plus the maximum ambient temperature or:
Protection Features
The LT1963A 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 opera-
tion, the junction temperature should not exceed 125°C.
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 100µA) 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.
I
I
V
I
P = 500mA(6V – 3.3V) + 10mA(6V) = 1.41W
1.41W(28°C/W) = 39.5°C
T
OUT(MAX)
OUT(MAX)
GND
JMAX
IN(MAX)
at (I
= 50°C + 39.5°C = 89.5°C
= 6V
OUT
(V
= 500mA
IN(MAX)
= 500mA, V
– V
OUT
LT1963A Series
IN
) + I
= 6V) = 10mA
GND
(V
IN(MAX)
)
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