ADP3333ARM-18 AD [Analog Devices], ADP3333ARM-18 Datasheet - Page 7

• Manufacturer Part Number: ADP3333ARM-18
• Description: High Accuracy Ultralow IQ, 300 mA, anyCAP Low Dropout Regulator
• Manufacturer: AD [Analog Devices]

Calculating Junction Temperature
Device power dissipation is calculated as follows:
Where I
and V
Assuming the worst-case operating conditions are I
300 mA, I
device power dissipation is:
The package used on the ADP3333 has a thermal resistance of
158 C/W for 4-layer boards. The junction temperature rise
above ambient will be approximately equal to:
So, to limit the junction temperature to 125 C, the maximum
allowable ambient temperature is:
Shutdown Mode
Applying a high signal to the shutdown pin, or connecting it to
the input pin, will turn the output ON. Pulling the shutdown
pin to 0.3 V or below, or connecting it to ground, will turn the
output OFF. In shutdown mode, the quiescent current is reduced
to less than 1 A.
P
D
OUT
LOAD
4 0
are the input and output voltages respectively.
GND
.
V
P
T
and I
T
D
J
= 2.6 mA, V
A
A(
MAX
3 0
GND
.
V
0 308
IN
.
V
)
are load current and ground current, V
300
125
V
W
OUT
IN
mA
C
= 4.0 V and V
158
I
LOAD
48 7
C W
4 2
.
.
/
C
V
V
IN
2 0
76 3
OUT
48 7
.
I
.
mA
.
GND
= 3.0 V, the
C
C
LOAD
308
=
mW
IN
Printed Circuit Board Layout Considerations
Use the following general guidelines when designing printed
circuit boards:
1. Keep the output capacitor as close to the output and ground
2. Keep the input capacitor as close to the input and ground
3. PC board traces with larger cross sectional areas will remove
4. Connect the NC pins (Pins 5, 6, and 8) to ground for better
5. The thermal resistance can be decreased by approximately
6. Use additional copper layers or planes to reduce the thermal
pins as possible.
pins as possible.
more heat from the ADP3333. For optimum heat transfer,
specify thick copper and use wide traces.
thermal performance.
10% by adding a few square centimeters of copper area to
the lands connected to the pins of the LDO.
resistance. Again, connecting the other layers to the ground and
NC pins of the ADP3333 is best, but not necessary. When
connecting the ground pad to other layers use multiple vias.
ADP3333