IRF7807PBF International Rectifier, IRF7807PBF Datasheet - Page 3

• Manufacturer Part Number: IRF7807PBF
• Description: MOSFET, 30V, 8.3A, 25 MOHM, 12 NC QG, SO-8
• Manufacturer: International Rectifier

Specifications of IRF7807PBF

• Lead Free Status / Rohs Status: RoHS Compliant part

Power MOSFET Selection for DC/DC
Converters
Control FET
in the switching elements of the circuit - Q1 and Q2.
Power losses in the high side switch Q1, also called the
Control FET, are impacted by the R
but these conduction losses are only about one half of
the total losses.
P
and Q
that is included in all MOSFET data sheets. The impor-
tance of splitting this gate-source charge into two sub
elements, Q
the gate driver between the time that the threshold volt-
age has been reached (t1) and the time the drain cur-
rent rises to I
begins to change. Minimizing Q
reducing switching losses in Q1.
capacitance of the MOSFET during every switching
cycle. Figure 2 shows how Q
lel combination of the voltage dependant (non-linear)
capacitance’s C
supply input buss voltage.
www.irf.com
P
loss
loss
Special attention has been given to the power losses
Power losses in the control switch Q1 are given by;
This can be expanded and approximated by;
This simplified loss equation includes the terms Q
Q
Q
Q
gs2
gs2
oss
= I
+ I ×
+ Q
+
= P
oss
is a sub element of traditional gate-source charge
is the charge that must be supplied to the output
indicates the charge that must be supplied by
(
⎛
⎜
⎝
(
⎛
⎝
which are new to Power MOSFET data sheets.
Q
rms
conduction
g
2
oss
× V
2
gs1
Q
× R
dmax
i
× V
g
gd
and Q
g
ds
× f
ds(on )
in
and C
× V
(t2) at which time the drain voltage
+ P
× f
)
gs2
in
)
switching
× f
, can be seen from Fig 1.
dg
⎞
⎠
when multiplied by the power
⎞
⎟ + I ×
⎠
oss
+ P
⎛
⎜
⎝
is formed by the paral-
gs2
ds(on)
drive
is a critical factor in
Q
+ P
i
of the MOSFET,
gs2
g
× V
output
in
× f
⎞
⎟
⎠
gs2
Figure 1: Typical MOSFET switching waveform
Synchronous FET
by;
*dissipated primarily in Q1.
P
P
loss
loss
The power loss equation for Q2 is approximated
t0
V
= P
= I
+ Q
+
GTH
(
(
⎛
⎜
⎝
conduction
rms
Q
t1
g
2
oss
2
× V
× R
× V
t2
g
+ P
IRF7807/APbF
ds(on)
× f
in
Drain Current
drive
× f
t3
)
)
⎞
⎠
+ P
+ Q
output
(
*
Drain Voltage
rr
× V
Gate Voltage
in
× f
4
1
2
)
3