PM6680ATR STMicroelectronics, PM6680ATR Datasheet - Page 33

• Manufacturer Part Number: PM6680ATR
• Description: IC CTRLR DUAL STEP DOWN 32VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6680ATR

• Applications: Controller, Embedded Computer System
• Voltage - Input: 6 ~ 36 V
• Number Of Outputs: 2
• Voltage - Output: 0.9 ~ 5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN, 32-VFQFPN
• For Use With: 497-6379 - BOARD EVALUATION FOR PM6680A497-6378 - BOARD EVALUATION FOR PM6680497-6425 - BOARD EVAL BASED ON PM6680A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6896-2; PM6680ATR

PM6680A
9.5
Power MOSFETS
Logic-level MOSFETs are recommended, since low side and high side gate drivers are
powered by LDO5. Their breakdown voltage VBR
In notebook applications, power management efficiency is a high level requirement. The
power dissipation on the power switches becomes an important factor in switching
selections. Losses of high-side and low-side MOSFETs depend on their working conditions.
The power dissipation of the high-side MOSFET is given by:
Equation 18
Maximum conduction losses are approximately:
Equation 19
where RDSon is the drain-source on resistance of the high side MOSFET.
Switching losses are approximately:
Equation 20
where t
As general rule, high side MOSFETs with low gate charge are recommended, in order to
minimize driver losses.
Below there is a list of possible choices for the high side MOSFET.
Table 13.
The power dissipation of the low side MOSFET is given by:
Equation 21
Maximum conduction losses occur at the maximum input voltage:
Manufacturer
P
switching
on
and t
ST
High side MOSFET manufacturer
=
off
V
IN
are the switching times of the turn
×
I (
LOAD
STS5NF60L
P
conduction
(max)
Type
P
DHighSide
2
−
P
∆
=
2
DLowSide
I
R
L
)
DSon
=
×
P
t
on
conduction
×
Gate charge (nC)
=
×
V
V
P
f
IN
OUT
sw
conduction
min
DSS
+
25
+
×
on
V
P
I
IN
LOAD
must be higher than V
switching
and turn
×
I (
(max)
LOAD
(max)
off
2
Rated reverse voltage (V)
phases of the MOSFET.
2
+
∆
Design guidelines
2
I
L
)
×
INmax
60
t
off
×
.
f
sw
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