LT3050EDDB#PBF Linear Technology, LT3050EDDB#PBF Datasheet - Page 21

• Manufacturer Part Number: LT3050EDDB#PBF
• Description: IC ADJ LDO REG 0.6V TO 44.5V 0.1A DFN-12
• Manufacturer: Linear Technology

Specifications of LT3050EDDB#PBF

• Primary Input Voltage: 45V
• Output Voltage Adjustable Range: 0.6V To 44.5V
• Dropout Voltage Vdo: 340mV
• No. Of Pins: 12
• Output Current: 100mA
• Operating Temperature Range: -40°C To +125°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
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 also can spread the heat generated by
power devices. The following tables list thermal resis-
tance as a function of copper area in a fi xed board size.
All measurements were taken in still air on a four-layer
FR-4 board with one ounce solid internal planes and two
ounce external trace planes with a total board thickness
of 1.6mm. For further information on thermal resistance
and using thermal information, refer to JEDEC standard
JESD51, notably JESD51-12.
Table 1. MSOP Measured Thermal Resistance
Table 2. DFN Measured Thermal Resistance
Calculating Junction Temperature
Example: Given an output voltage of 5V, an input voltage
range of 12V ±5%, a maximum output current range of
75mA and a maximum ambient temperature of 85°C, what
will the maximum junction temperature be?
2500 sq mm 2500 sq mm 2500 sq mm
1000 sq mm 2500 sq mm 2500 sq mm
225 sq mm 2500 sq mm 2500 sq mm
100 sq mm 2500 sq mm 2500 sq mm
TOPSIDE
COPPER AREA
2500 sq mm
1000 sq mm
225 sq mm
100 sq mm
TOPSIDE
COPPER AREA
BACKSIDE
BOARD AREA
2500 sq mm
2500 sq mm
2500 sq mm
2500 sq mm
BOARD
AREA
(JUNCTION-TO-AMBIENT)
(JUNCTION-TO-AMBIENT)
THERMAL RESISTANCE
THERMAL RESISTANCE
44°C/W
45°C/W
47°C/W
49°C/W
40°C/W
43°C/W
45°C/W
41°C/W
The power dissipated by the device equals:
where,
So,
Using a DFN package, the thermal resistance ranges from
44°C/W to 49°C/W depending on the copper area. So the
junction temperature rise above ambient approximately
equals:
The maximum junction temperature equals the maximum
ambient temperature plus the maximum junction tempera-
ture rise above ambient or:
Protection Features
The LT3050 incorporates several protection features that
make it ideal for use in battery-powered circuits. In ad-
dition to the normal protection features associated with
monolithic regulators, such as current limiting and thermal
limiting, the device also protects against reverse-input
voltages, reverse-output voltages and reverse output-to-
input voltages.
Current limit protection and thermal overload protection
protect the device against current overload conditions at
the output of the device. For normal operation, do not
exceed a junction temperature of 125°C.
I
I
V
I
P = 75mA • (12.6V - 5V) + 1.5mA • 12.6V = 0.589W
0.589W • 49°C/W = 28.86°C
T
OUT(MAX)
OUT(MAX)
GND
JMAX
IN(MAX)
at (I
= 85°C + 28.86°C = 113.86°C
= 12.6V
OUT
* (V
= 75mA
= 75mA, V
IN(MAX)
– V
IN
OUT
= 12V) = 1.5mA
LT3050 Series
) + I
GND
* V
IN(MAX)
21
3050fa