ADP5040 Analog Devices, ADP5040 Datasheet - Page 33

• Manufacturer Part Number: ADP5040
• Description: Micro PMU with 1.2 A Buck Regulator and Two 300 mA LDOs
• Manufacturer: Analog Devices

Data Sheet
Junction Temperature
In cases where the board temperature, T
thermal resistance parameter, θ
junction temperature rise. T
the formula
The typical θ
38°C/W (see Table 6). A very important factor to consider is
that θ
per JEDEC standard, and real applications may use different
sizes and layers. To remove heat from the device, it is important
to maximize the use of copper. Copper exposed to air dissipates
heat better than copper used in the inner layers. The exposed
pad (EP) should be connected to the ground plane with several
vias as shown in Figure 109.
APPLICATION DIAGRAM
T
JA
J
= T
is based on a 4-layer, 4 inch × 3 inch, 2.5 oz copper, as
A
+ (P
JA
value for the 20-lead, 4 mm × 4 mm LFCSP is
D
× θ
JA
)
V
V
V
IN1
IN2
IN3
TO 5.5V
TO 5.5V
TO 5.5V
J
= 2.3V
= 1.7V
= 1.7V
is calculated from T
JA
, can be used to estimate the
1µF
1µF
OFF
C2
OFF
C3
OFF
4.7µF
R
30Ω
A
C1
FILT
ON
, is known, the
ON
ON
AVIN
VIN1
VIN2
VIN3
EN1
EN2
EN3
10
13
16
A
6
7
4
3
and P
Figure 108. Application Diagram
EN_LDO1
EN_LDO2
EN_BK
D
(ANALOG)
(DIGITAL)
using
BUCK
LDO1
LDO2
(14)
EP
Rev. 0 | Page 33 of 40
AGND
11
12
17
14
15
1
8
9
2
VOUT1
SW
FB1
PGND
MODE
VOUT2
FB2
VOUT3
FB3
If the case temperature can be measured, the junction temperature
is calculated by
where:
T
θ
When designing an application for a particular ambient
temperature range, calculate the expected
dissipation (P
Equation 8 to Equation 13. From this power calculation, the
junction temperature, T
The reliable operation of the buck regulator and the LDO
regulator can be achieved only if the estimated die junction
temperature of the
Reliability and mean time between failures (MTBF) is highly
affected by increasing the junction temperature. Additional
information about product reliability can be found in the
Analog Devices, Inc., Reliability
at http://www.analog.com/reliability_handbook.
JC
R2
C
is the case temperature.
is the junction-to-case thermal resistance provided in Table 6.
T
FPWM
J
1µH
R7
R8
L1
R1
= T
R3
R4
PWM/PSM
C
+ (P
D
) due to the losses of all channels by using
C4
10µF
C6
2.2µF
D
× θ
ADP5040
C5
2.2µF
JC
)
J
, can be estimated using Equation 14.
V
1.2A
V
300mA
V
300mA
(Equation 14) is less than 125°C.
OUT1
OUT2
OUT3
Handbook, which is available
AT
AT
AT
ADP5040
ADP5040
power
(15)