PM6686 STMicroelectronics, PM6686 Datasheet - Page 40

• Manufacturer Part Number: PM6686
• Description: Dual Step-down Controller With Adjustable Voltages, Adjustable Ldo And Auxiliary Charge Pump Controller For Notebook
• Manufacturer: STMicroelectronics

Application information
10.1.4
40/50
Finally the output capacitor choice deeply impacts on the load transient response. Below
there is a list of some capacitor manufacturers.
Output capacitor manufacturer
Table 16.
MOSFET
Logic-level MOSFETs are recommended, since low-side and high-side gate drivers are
powered by PVCC. Their breakdown voltage (VBRDSS) must be higher than the maximum
input voltage.
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 14
Maximum conduction losses are approximately:
Equation 15
Where R
Switching losses are approximately:
Equation 16
Where t
MOSFETs.
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 MOSFETs.
Manufacturer
SANYO
SANYO
P
switching
on
DS(on)
and t
Input capacitor manufacturer
=
is the drain-source on resistance of the high-side MOSFET.
off
POSCAP TPB
POSCAP TPF
V
are the switching times of the turn off and turn off phases of the
IN
Series
×
I (
LOAD
P
conduction
(max)
P
Doc ID 15281 Rev 4
DHighSide
2
Capacitor value (µF)
−
=
Δ
2
I
R
L
150 to 330
150 to 470
DSon
)
=
×
P
t
on
conduction
×
×
V
V
f
IN
sw
OUT
min
+
+
×
V
P
I
IN
LOAD
switching
×
Rated voltage (V)
I (
LOAD
(max)
2.5 to 6.3
2.5 to 6.3
(max)
2
2
+
Δ
2
I
L
)
×
ESR max (mΩ)
t
off
35 to 65
7 to 15
×
f
sw
PM6686