lt3010hms8e-trpbf Linear Technology Corporation, lt3010hms8e-trpbf Datasheet - Page 10

• Manufacturer Part Number: lt3010hms8e-trpbf
• Description: 50ma, 3v To 80v Low Dropout Micropower Linear Regulator
• Manufacturer: Linear Technology Corporation

APPLICATIONS INFORMATION
LT3010/LT3010-5
capacitance change over temperature. Capacitance change
due to DC bias with X5R and X7R capacitors is better than
Y5V and Z5U capacitors, but can still be signifi cant enough
to drop capacitor values below appropriate levels. Capaci-
tor DC bias characteristics tend to improve as component
case size increases, but expected capacitance at operating
voltage should be verifi ed.
Voltage and temperature coeffi cients 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, simi-
lar 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.
10
Figure 4. Ceramic Capacitor Temperature Characteristics
Figure 3. Ceramic Capacitor DC Bias Characteristics
–100
–100
–20
–40
–60
–80
–20
–40
–60
–80
20
40
20
0
0
–50
0
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
–25
2
4
DC BIAS VOLTAGE (V)
0
TEMPERATURE (°C)
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF
6
25
8
X5R
Y5V
50
10
X5R
Y5V
75
12
100
14
30105 F03
30105 F04
125
16
Thermal Considerations
The power handling capability of the device will be lim-
ited by the maximum rated junction temperature (125°C,
LT3010E or 140°C, LT3010H). The power dissipated by
the device will be made up of two components:
1. Output current multiplied by the input/output voltage
2. GND pin current multiplied by the input voltage:
The GND pin current can be found by examining the GND
Pin Current curves in the Typical Performance Character-
istics. Power dissipation will be equal to the sum of the
two components listed above.
The LT3010 series regulators have internal thermal limiting
designed to protect the device during overload condi-
tions. For continuous normal conditions the maximum
junction temperature rating of 125°C (LT3010E) or 140°C
(LT3010H) 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 gener-
ated by power devices.
The following table lists 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. Measured Thermal Resistance
The thermal resistance junction-to-case (θ
at the exposed pad on the back of the die, is 16°C/W.
2500 sq mm 2500 sq mm
1000 sq mm 2500 sq mm
225 sq mm
100 sq mm
TOPSIDE
differential: I
I
GND
COPPER AREA
• V
IN
2500 sq mm
2500 sq mm
BACKSIDE
OUT
• (V
IN
BOARD AREA
2500 sq mm
2500 sq mm
2500 sq mm
2500 sq mm
– V
OUT
) and,
(JUNCTION-TO-AMBIENT)
THERMAL RESISTANCE
JC
40°C/W
45°C/W
50°C/W
62°C/W
), measured
30105fc