GM6155 ETC2 [List of Unclassifed Manufacturers], GM6155 Datasheet - Page 6

• Manufacturer Part Number: GM6155
• Description: 150mA LOW - NOISE LDO REGULATOR
• Manufacturer: ETC2 [List of Unclassifed Manufacturers]

6
GM6155
Figure 3. includes a 470pF capacitor for low-noise
operation and shows EN (pin 3) connected to IN (pin 1)
for an application where enable/ shutdown is not
required. C
The actual power dissipation of the regulator circuit can be determined using the equation:
Substituting P
the maximum operating conditions for the regulator circuit. For example, when operating the GM6155 at room
temperature with a minimum footprint layout, the maximum input voltage for a set output current can be
determined as follows:
The junction-to-ambient thermal resistance for the minimum footprint is 220°C/ W, from Table 1. The maximum
power dissipation must not be exceeded for proper operation. Using the output voltage of 3.3V and an output
current of 150mA, the maximum input voltage can be determined. From the Electrical Characteristics table, the
maximum ground current for150mA output current is 2500µA or 2.5mA.
Therefore, a 3.3V application at 150mA of output current can accept a maximum input voltage of 6.2V in a
SOT-25 package. For a full discussion of heat sinking and thermal effects on voltage regulators.
Fixed Regulator Applications
Figure 3. Ultra-Low-Noise Fixed Voltage Application
Adjustable Regulator Applications
The GM6155 can be adjusted to a specific output voltage by using two externa resistors (Figure 5). The resistors set the
output voltage based on the following equation:
V
OUT
IN
D(max)
= 2.2µF minimum.
1
2
3
Parameter
for P and solving for the operating conditions that are critical to the application will give
SOT-23-5
D
4
5
455mW = (V
455mW = V • 150mA - 495mA + V • 2.5mA
950mW = V • 152.5mA
V
IN(max)
P
P
470pF
P = (V - V
Table 1. SOT-25 Thermal Resistance
V
D(max)
D(max)
D
OUT
2.2µF
V
R
OUT
Minimum Footprint
q
JA
= 6.23V
=
= 455mW
= 1.242V X (
IN
Recommended
220°C/ W
(125°C - 25°C)
IN
IN
IN
220°C/W
OUT
- 3.3V) 150mA + V • 2.5mA
) I
Figure 4. is an example of a low-noise configuration
where C
Figure 4. Low-Noise Fixed Voltage Application
OUT
Shutdown
Enable
R2
R1
+ V I
BYP
+1)
R
Copper Clad
IN GND
q
JA
170°C/ W
is not required. C
1" Square
V
EN
IN
IN
IN
1
3
2
OUT
130°C/ W
R
5
4
q
= 1µF minimum.
JC
V
OUT
1.0µF