FPF1039UCX Fairchild Semiconductor, FPF1039UCX Datasheet - Page 12

• Manufacturer Part Number: FPF1039UCX
• Description: Power Switch ICs - Power Distribution Low On-Res SlewRate Cntrlld Load Switch
• Manufacturer: Fairchild Semiconductor

Specifications of FPF1039UCX

• On Resistance (max): 21 mOhms
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Maximum Power Dissipation: 1.2 W
• Mounting Style: SMD/SMT
• Off Time (max): 32 ms
• On Time (max): 4.4 ms
• Supply Current: 5.5 uA
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 1.2 V
• Switch Current (typ): 2 A
• Package / Case: WLCSP-6
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

© 2010 Fairchild Semiconductor Corporation
FPF1038 / FPF1039 • Rev. 1.0.0
Application Information
Input Capacitor
This IntelliMAX
capacitor. To reduce device inrush current effect, a
0.1µF ceramic capacitor, C
the VIN pin. A higher value of C
the voltage drop experienced as the switch is turned on
into a large capacitive load.
Output Capacitor
This IntelliMAX
capacitor. However, if parasitic board inductance forces
V
C
Fall Time
Device output fall time can be calculated based on RC
constant of the external components as follows:
Application Specifics
At maximum operational voltage (V
rush current might be higher than expected. Spike
current should be taken into account if V
output capacitor is much larger than the input capacitor.
Input current can be calculated as:
Where switch and wire resistances are neglected and
capacitors are assumed ideal.
t
I
F
IN
OUT
OUT
) t (
=
, should be placed between V
R
below GND when switching off; a 0.1µF capacitor,
≈
L
V
R
×
OUT
LOAD
C
L
) t (
×
2
+
TM
TM
2 .
Figure 38.
(
C
LOAD
switch works without an output
switch doesn’t require an input
−
C
IN
IN
, is recommended close to
)
Device Setup
dV
IN
OUT
dt
can be used to reduce
OUT
) t (
IN
and GND.
=5.5V) device in-
IN
>5V and the
(3)
(1)
12
where t
C
The same equation works for a device with a pull-down
output resistor. R
pull-down and an external output resistor combination as:
where t
R
output capacitor.
Resistive Output Load
If resistive output load is missing, the IntelliMAX
switch without a pull-down output resistor does not
discharge the output voltage. Output voltage drop
depends, in that case, mainly on external device leaks.
Estimating
formula for slew rate (dV
written as
Where supply voltage VIN is in volts, capacitances are
in micro farads and resistance in ohms.
Example: If V
R
Maximum spike current is 1.8A, while average ramp-up
current is:
t
max(
I
max
≈
F
IN
L
PD
LOAD
. 2
is output capacitor.
=
) t (
=65Ω is output pull-down resistor, and C
75
( )
I
R
R
I
IN
=50Ω, calculate the spike current by:
IN
≈
L
/
L
)
F
V
50
F
R
=
×
+
=
OUT
is 90% to 10% fall time; R
LOAD
is 90% to 10% fall time, R
10
R
R
10
+
5
100
PD
PD
∗
R
5 .
) t (
V
50
V
LOAD
OUT
IN
∗
IN
+
×
+
. 0
=5.5V, C
(
C
(t)=V
(
C
0022
L
100
L
LOAD
is replaced by a parallel connected
+
×
(
C
−
2
IN
=
LOAD
10
2 .
/10 and
. 0
−
OUT
)(
C
275
LOAD
. 0
IN
(t)/dt), spike current can be
−
05
)
A
C
dV
=100µF, C
∗
IN
5
IN
dt
5 .
)
⎛
⎜
⎝
) t (
. 0
−
using experimental
L
05
. 0
is output load, and
255
V
L
IN
is output load,
A )
−
IN
www.fairchildsemi.com
. 0
=10µF, and
=
255
1
8 .
L
A
⎞
⎟
⎠
is the
(4)
(6)
(2)
(5)
TM