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FPF2300/02/03 — Dual-Output Current Limit Switch
June 2009
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3
FPF2300/02/03
Dual-Output Current Limit Switch
Features
!1.8 to 5.5V Input Voltage Range
!Typical RON = 75mΩ at IN = 5.5V
!1.3A Current Limit (Typical)
!Slew Rate Controlled
!Reversed Current Blocking when Disabled
!ESD Protected, Above 4000V HBM
!Independent Thermal Shutdown
!UVLO
!RoHS Compliant
Applications
!Notebook Computing
!Peripheral USB Ports
!Networking / USB Based Equiptment
Description
The FPF2300/02/03 are dual-channel load switches of
IntelliMAX™ family. The FPF2300/02/03 consist of dual,
independent, current-limited, slew rate controlled, P-
channel MOSFET power switches. Slew rated turn-on
prevents inrush current from glitching supply rails. The
input voltage range operates from 1.8V to 5.5V to fulfill
today's USB device supply requirements. Switch control
is accomplished by a logic input (ON) capable of
interfacing directly with low-voltage control signal.
For the FPF2302, if the constant current condition per-
sists after 10ms, these parts shut down the switch and
pull the fault signal pin (FLAGB) LOW. The FPF2300 has
an auto-restart feature that turns the switch on again
after 504ms if the ON pin is still active. For the FPF2303,
a current limit condition immediately pulls the fault signal
pin LOW and the part remains in the constant-current
mode until the switch current falls below the current limit.
For the FPF2300 through FPF2303, the current limit is
typically 1.3A for each switch to align with notebook
computing applications. FPF2300/02/03 is available in
both SO8 and MLP 3X3mm 8-lead packages.
Figure 1. 8-Lead SOP Figure 2. 8-Lead MLP (3x3mm)
Ordering Information
For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
Part Number
Minimum
Current
Limit
Current Limit
Blanking Time
Eco
Status
Auto
Restart
ON Pin
Activity Mode Package
FPF2300MX 1100mA 10ms RoHS 504ms Active LOW Restart 8-Lead SO8
FPF2302MX 1100mA 10ms RoHS N/A Active LOW Latch Off 8-Lead SO8
FPF2303MX 1100mA 0ms RoHS N/A Active LOW Constant
Current 8-Lead SO8
FPF2300MPX 1100mA 10ms Green 504 Active LOW Restart 8-Lead Molded Lead-
less Package (MLP)
FPF2302MPX 1100mA 10ms Green N/A Active LOW Latch Off 8-Lead Molded Lead-
less Package (MLP)
FPF2303MPX 1100mA 0ms Green N/A Active LOW Constant
Current
8-Lead Molded Lead-
less Package (MLP)
FPF2300/02/03 — Dual-Output Current Limit Switch
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 2
Application Circuit
Figure 3. Typical Application
Functional Block Diagram
Figure 4. Block Diagram
ONOFF ONA
IN
GND
FPF2300/2/3
FLAGB(B)
OUTA TO LOAD A
FLAGB(A)
ONOFF ONB OUTB TO LOAD B
CIN
COUTB COUTA
IN = 1.8V-5.5V
IN
ONA
ONB
OUTA
FLAGB(A)
OUTB
FLAGB(B)
GND
CURRENT
LIMIT B
THERMAL
PROTECTION B
CONTROL
LOGIC B
REVERSE
CURRENT
BLOCKING
CURRENT
LIMIT A
THERMAL
PROTECTION A
CONTROL
LOGIC A
REVERSE
CURRENT
BLOCKING
UVLO
FPF2300/02/03 — Dual-Output Current Limit Switch
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 3
Pin Configuration
Figure 5. Pin Configurations
Pin Description
Pin # Name Function
1 GND Ground
2 IN Supply Input: Input to the power switch and the supply voltage for the IC.
3 ONA ON / OFF control input of power switch A. Active LOW
4 ONB ON / OFF control input of power switch B. Active LOW
5FLAGB(B)
Fault Output B, Active LO, open drain output which indicates an over supply, UVLO
and thermal shutdown.
6 OUTB Switch Output: Output of the power switch B
7 OUTA Switch Output: Output of the power switch A
8FLAGB(A)
Fault Output A, Active LO, open drain output which indicates an over supply, UVLO
and thermal shutdown.
9(MLP) Thermal Pad IC Substrate, which can be connected to GND for better thermal performance. Do not
connect to other pins.
SO8
1
GND
2
3
4
8
7
6
5
IN
ONA
ONB
FLAGB(A)
OUTA
OUTB
FLAGB(B)
GND
IN
ONAOUTB
FLAGB(A)
MLP 3X3mm 8-Lead Bottom View
8
7
63
2
1
OUTA
FLAGB(B) 5ONB
4
9
FPF2300/02/03 — Dual-Output Current Limit Switch
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 4
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be opera-
ble above the recommended operating conditions and stressing the parts to these levels is not recommended. In addi-
tion, extended exposure to stresses above the recommended operating conditions may affect device reliability. The
absolute maximum ratings are stress ratings only.
Notes:
1. Two-layer PCB of 2s0p from JEDEC STD 51-3.
2. Four-layer PBD of 2s0p from JEDEC STD 51-7.
3. Soldered thermal pad on a two-layer PCB without vias based on JEDEC STD 51-3.
4. Soldered thermal pad on a four-layer with two vias connected with GND plane base on JEDEC STD 51-5, 7.
Recommended Operating Range
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended
operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not
recommend exceeding them or designing to absolute maximum ratings.
Symbol Parameter Min. Max. Unit
IN, OUTA, OUTB, ONA, ONB, FLAGB(A), FLAGB(B) to GND -0.3 6.0 V
PDPower Dissipation
SO8 0.8(1)
W
1.4(2)
MLP 0.6(3)
2.2(4)
TSTG Storage Temperature -65 +150 °C
ΘJA Thermal Resistance, Junction-to-Ambient
SO8 158(1)
°C/W
92(2)
MLP 216(3)
57(4)
ESD Electrostatic Discharge Protection Human Body Model, JESD22-A114 4000 V
Charged Device Model, JESD22-C101 2000
Symbol Parameter Min. Max. Unit
IN Supply Input 1.8 5.5 V
TAAmbient Operating Temperature -40 +85 °C
FPF2300/02/03 — Dual-Output Current Limit Switch
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 5
Electrical Characteristics
IN = 1.8 to 5.5V, TA = -40 to +85°C unless otherwise noted. Typical values are at IN = 3.3V and TA = 25°C.
Note:
5. FPF2303 has a 10ms startup FLAGB blanking time when the part is turned on via the ON pin to ensure transient load currents settle.
Figure 6. Timing Diagram
Symbol Parameter Conditions Min. Typ. Max. Units
Basic Operation
VIN Operating Voltage 1.8 5.5 V
IQQuiescent Current IN = 5.5V, VONA = VONB = 0V, IOUT = 0mA 52.5 94.5 μA
ISD IN Shutdown Current VONA = VONB = 5.5V, IN = 5.5V
OUTA = OUTB = Short to GND, 3μA
RON On Resistance IN = 5.5V, IOUT = 200mA, TA = 25°C 75 140 mΩ
IN = 5.5V, IOUT = 200mA, TA = -40°C to 85°C 90
VIH ON Input Logic High Voltage (ON) IN = 1.8V 0.8 V
IN = 5.5V 1.4
VIL ON Input Logic Low Voltage IN = 1.8V 0.5 V
IN = 5.5V 0.9
ION ON Input Leakage VON = IN or GND -1 1 μA
FLAGB Output Logic Low Voltage IN = 5.5V, ISINK = 1mA 0.1 0.2 V
IN = 1.8V, ISINK = 1mA 0.15 0.30
FLAGB Output High Leakage Current IN = VON = 5V 1 μA
Protections
ILIM Current Limit IN = 3.3V, VOUTA = VOUTB = 3V, TA = 25°C 1.1 1.3 1.5 A
TSD Thermal Shutdown
Shutdown Threshold 140
°CReturn from Shutdown 130
Hysteresis 10
VUVLO Under-Voltage Shutdown IN Increasing 1.55 1.65 1.75 V
VUVLO_HYS Under-Voltage Shutdown Hysteresis 50 mV
Dynamic
tON Turn-On Time RL = 500Ω, CL = 0.1μF 113.5 μs
tOFF Turn-Off Time RL = 500Ω6μs
tROUTA, OUTB Rise Time RL = 500Ω, CL = 0.1μF13.5μs
tBLANK Over-Current Blanking Time FPF2300, FPF2302 5 10 20 ms
tRSTRT_BLANK Startup FLAGB Blanking Time FPF2303(5) 51020ms
tRSRT Auto-Restart Time FPF2300 504 ms
tCLR Current Limit Response Time IN = 3.3V, Moderate Over-Current Condition 20 μs
90%
10%
90%
10%
50% 50%
10%
90%
tR
tDON tDOFF
OUT
tF
OUT
ON
tON = tR + tDON tOFF = tF + tDOFF
FPF2300/02/03 — Dual-Output Current Limit Switch
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 6
Typical Characteristics
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
1.8 2.2 2.5 2.9 3.3 3.7 4.0 4.4 4.8 5.1 5.
5
SUPPLY VOLTAGE
(
V
)
SUPPLY
CURRENT
(
u
A)
ONA = ONB = 0V
25°C
8
5°
C
-40°
C
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
IN SHUTDOWN CURRENT (uA)
IN = ONA = ONB = 5.5V
OUT = 0V
60
70
80
90
100
110
120
130
140
150
160
1.82.22.52.93.33.74.04.44.85.15.
5
SUPPLY VOLTAGE
(
V
)
ON RESISTANCE (mOhms)
R
ON
A
R
ON
B
ONA = ONB = 0
V
I
OUT
= 200mA
T
A
= 25°C
Figure 10. RON vs. Supply Voltage (MLP)
Figure 11. RON vs. Temperature (SO8) Figure 12. RON vs. Temperature (MLP)
Figure 9. IN Shutdown Current vs. Temperature
Figure 7. Quiescent Current vs. Supply Voltage Figure 8. Quiescent Current vs. Temperature
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
-40 -15 10 35 60 8
5
T
J
, JUNCTI ON TEMPERATURE (°C)
I
Q
CURRENT (uA)
IN = 3.3V
IN = 5.5V
IN = 1.8V
ONA = ONB = 0V
60
70
80
90
100
110
120
130
140
150
160
1.82.22.52.93.33.74.04.44.85.15.
5
SUPPLY VOLTAGE
(
V
)
ON RESISTANCE (mOhms)
R
ON
A
R
ON
B
ONA = ONB = 0V
I
OUT
= 200mA
T
A
= 25°C
50
55
60
65
70
75
80
85
90
95
100
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
ON RESISTANCE (mOhm)
R
ON
A
R
ON B
IN = 5.5V
IOUT = 200mA
ONA = ONB = 0V
FPF2300/02/03 — Dual-Output Current Limit Switch
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 7
Typical Characteristics
50
55
60
65
70
75
80
85
90
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
ON RESISTANCE (mOhm)
R
ON
A
R
ON
B
IN = 5.5V
I
OUT
= 200mA
ONA = ONB = 0V
Figure 16. ON Low Voltage vs. Temperature
Figure 17. Current Limit vs. Supply Voltage Figure 18. Current Limit vs. Temperature
Figure 15. ON High Voltage vs. Temperature
Figure 13. RON vs. Temperature (SO8) Figure 14. ON Threshold Voltage vs. Supply Voltage
0.0
0.3
0.5
0.8
1.0
1.3
1.5
1.8 2.2 2.5 2.9 3.3 3.7 4.0 4.4 4.8 5.1 5.
5
SUPPLY VOLTAGE
(
V
)
ON THRESHOLD VOLTAGE (V)
V
IH
V
I
L
T
A
= 25°C
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
ON THRESHOLD VOLTAGE (V)
IN = 3.3V
IN = 5.5V
IN = 1.8V
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
ON THRESHOLD VOLTAGE (V)
IN = 3.3V
IN = 5.5V
IN = 1.8V
1250
1260
1270
1280
1290
1300
1310
1320
1330
1340
1350
1.8 2.2 2.5 2.9 3.3 3.7 4.0 4.4 4.8 5.1 5.
5
SUPPLY VOLTAGE
(
V
)
CURRENT LIMIT (mA)
ILIM(Typ)A
T
A
= 25°C
ILIM(Typ)B
1250
1260
1270
1280
1290
1300
1310
1320
1330
1340
1350
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
CURRENT LIMIT (mA)
IN = 3.3V
OUTA = OUTB = 3V
ONA = ONB = 0V
ILIM(Typ)
A
ILIM(Typ)
B
FPF2300/02/03 — Dual-Output Current Limit Switch
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 8
Typical Characteristics
1
10
100
1000
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
TURN ON/OFF DELAY TIME (us)
t
DOFF
t
DON
IN = 3.3V
R
L
= 500 Ohm
s
C
L
= 0.1 uF
IN = 3.3V
R
L
= 500 Ohm
s
OUT
2V/DIV
IN = 5V
ON = 3.3V
COUT = 0.1μF
RL = 500Ω
ON
2V/DIV
IN
2V/DIV
200μs/DIV
Figure 23. tRSTRT vs. Temperature Figure 24. tON Response
Figure 22. tRSTRT_BLANK vs. TemperatureFigure 21. tBLANK vs. Temperature
Figure 19. tDON / tDOFF vs. Temperature Figure 20. tRISE / tFALL vs. Temperature
0
2
4
6
8
10
12
14
16
18
20
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
RISE/FALL TIME (us)
t
F
t
R
IN = 3.3V
R
L
= 500 Ohm
s
C
L
= 0.1 uF
IN = 3.3V
R
L
= 500 Ohm
s
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
OVER CURRENT BLANKING TIME (ms)
FLAGB(A)
FLAGB(B)
FPF2300/2
IN = 3.3V
ONA = ONB = 0
V
7.0
7.5
8.0
8.5
9.0
9.5
10.0
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
STARTUP FLAGB BLANKING TIME (ms)
FLAGB(A
)
FLAGB(B)
FPF2303
IN = 3.3V
ONA = ONB = 0
V
500.0
520.0
540.0
560.0
580.0
600.0
620.0
-40 -15 10 35 60 8
5
T
J
, JUNCTION TEMPERATURE (°C)
RESTART TIME (ms)
OUTA
OUTB
FPF2300
IN = 3.3V
ONA = ONB = 0
V
FPF2300/02/03 — Dual-Output Current Limit Switch
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 9
Typical Characteristics
OUT
2V/DIV
IN = 5V
ON = 3.3V
COUT = 0.1μF
RL = 500Ω
ON
2V/DIV
IN
2V/DIV
200μs/DIV
IN = 5V
ON = 3.3V
RL = 5Ω
IN
5V/DIV
ON
5V/DIV
200μs/DIV
IOUT
1A/DIV
COUT = 47μF
COUT = 100μF
COUT = 220μF
COUT = 470μF
Figure 29. Current Limit at Startup with
Different Output Capacitor
Figure 30. Output Voltage at Startup with
Different Output Capacitor
Figure 27. Startup FLAGB Blanking Time (FPF2303)
Figure 25. tOFF Response Figure 26. Over-Current Blanking Time (FPF2300/2)
Figure 28. Auto-Restart Time (FPF2300)
2ms/DIV
OUT
5V/DIV
IN = 5V
COUT = 10μF
RL = 2.8Ω
ON
2V/DIV
FLAGB
2V/DIV
IOUT
1A/DIV
tBLANK
2ms/DIV
OUT
2V/DIV
COUT = 10μF
RL = 3.3Ω
ON
2V/DIV
FLAGB
2V/DIV
IOUT
1A/DIV
tSTART_BLANK
100ms/DIV
OUT
5V/DIV
IN = 5V
COUT = 10μF
RL = 2.8Ω
ON
2V/DIV
FLAGB
2V/DIV
IOUT
1A/DIV
tRSTRT
IN = 5V
ON = 3.3V
RL = 5Ω
IN
5V/DIV
ON
5V/DIV
200μs/DIV
OUT
5V/DIV
COUT = 47μFC
OUT = 220μF
COUT = 100μFC
OUT = 470μF
FPF2300/02/03 — Dual-Output Current Limit Switch
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 10
Typical Characteristics
OUTB
2V/DIV
IN = 5V
ON = 3.3V
COUTA = 100μF
COUTB = 100μF
RLA = RLB = 1Ω
IN
5V/DIV
ON
2V/DIV
400μs/DIV
OUTA
2V/DIV
Figure 33. Inrush Response During Capacitive Load
Hot Plug-In Event
Figure 31. Current Limit Response Time Both
Channels are in OC
Figure 32. Startup FLAGB Blanking Time
Figure 34. Inrush Response During Capacitive and
Resistive Load Hot Plug-In Event
FLAGB(B)
2V/DIV
IN = 5V
ON = 3.3V
COUTA = 100μF
COUTB = 100μF
RLA = RLB = 1Ω
IN
5V/DIV
ON
2V/DIV
10ms/DIV
FLAGB(A)
2V/DIV
OUT
5V/DIV
IN = 5V
COUT = 47μF
CL = 470μF
RL = 5Ω
IN
5V/DIV
ON
5V/DIV
1ms/DIV
IOUT
500mA/DIV
OUT
5V/DIV
IN = 5V
CIN = 10μF
COUT = 100μF
CL = 47μF
IN
5V/DIV
ON
5V/DIV
200μs/DIV
IOUT
2A/DIV
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 11
FPF2300/02/03 — Dual-Output Current Limit Switch
Description of Operation
The FPF2300, FPF2302, and FPF2303 are dual-output current-
limit switches designed to meet notebook computer, peripheral
USB port, and point-of-load (POL) application power requirements.
Dual-output current can be used where dual or quad USB ports are
powered by hosts or self-powered hubs. The FPF230X family
offers control and protection while providing optimum operation
current for a safe design practice. The core of each switch is a
typical 75mΩ (IN = 5.5V) P-channel MOSFET and a controller
capable of functioning over an input operating range of 1.8-5.5V.
The FPF230X family offers current limiting, UVLO (under-voltage
lockout), and thermal shutdown protection per each switch. In the
event of an over-current condition, the load switch limits the load to
current limit value. The minimum current limit is set to 1100mA.
On/Off Control
The ON pin is active LOW for FPF2300/2/3 and controls the state
of the switch. Pulling the ON pin continuous to LOW holds the
switch in the ON state. The switch moves into the OFF state when
the ON pin is pulled HIGH or if a fault is encountered. For all
versions, an under-voltage on input voltage or a junction
temperature in excess of 140°C overrides the ON control to turn off
the switch. In addition, excessive currents cause the switch to turn
off in the FPF2300 and FPF2302 after a 10ms blanking time. The
FPF2300 has an auto-restart feature that automatically turns the
switch ON again after 504ms. For the FPF2302, the ON pin must
be toggled to turn on the switch again. The FPF2303 does not turn
off in response to an over-current condition, but remains operating
in a constant-current mode as long as ON is enabled and the
thermal shutdown or UVLO is not activated. The ON pin does not
have a pull-down or pull-up resistor and should not be left floating.
Current Limiting
The current limit ensures that the current through the switch
doesn't exceed a maximum value, while not limiting at less than a
minimum value. FPF230X family has dual-output load switches
being housed in one package. The minimum current at which both
switches start limiting the load current is set to 1100mA. The
FPF2300 and FPF2302 have a blanking time of 10ms (typical),
during which the switch acts as a constant current source. At the
end of the blanking time, the switch is turned off. The FPF2303 has
no current limit blanking period, so it remains in a constant current
state until the ON pin of the affected switch is deactivated or the
thermal shutdown turns off the switch.
Fault Reporting
Over-current, input under-voltage, and over-temperature fault
conditions are signaled out by the FLAGB pin going LOW. A UVLO
fault is reported on both FLAGB(A) and FLAGB(B) simultaneously,
while over-current and over-temperature condition faults are
reported independently. FPF2300 and FPF2302 have a current
fault blanking feature that prevents over-current faults shorter than
the blanking time (tBLANK(Typ) = 10ms) from triggering the fault
signal (FLAGB) output.
If the over-current condition persists beyond the blanking time, the
FPF2300 pulls the FLAGB pin LOW and shuts the switch off. If the
ON pin is kept active, an auto-restart feature releases the FLAGB
pin and turns the switch on again after a 504ms auto-restart time
(tRSTRT). If the over-current condition persists beyond the blanking
time, the FPF2302 has a latch-off feature that pulls the FLAGB pin
LOW and shuts the switch off. The switch is kept off and the
FLAGB pin kept LOW until the ON pin is toggled. The FPF2303
responds to an overload condition by immediately pulling the
FLAGB pin LOW and the switch remains in constant current mode
until the output overload condition is removed. The FPF2303 has a
startup blanking feature that prevents current faults related to star-
tup transients from triggering the FLAGB output. The startup blank-
ing feature is effective for the first 10ms (typical) following device
turn-on via ON pin.
The FLAGB outputs are two open-drain MOSFETs that require a
pull-up resistor on each FLAGB pin. FLAGB can be pulled HIGH to
a voltage source other than input supply with maximum 5.5V. A
100KΩ pull-up resistor is recommended. When the ON pin is inac-
tive, the FLAGB is disabled to reduce current draw from the supply.
If the FLAGB is not used, the FLAGB can be connected to ground
on the PCB.
.
device wakeup
device wakeup
ON
IN
FLAGB
OUT
ILOAD
ILIMIT
10% VOUT
90% VOUT
RISE
TIME
VIN
ON
FLAGB
RL*
VOUT
tBLANK
ILOAD
ILIMIT
tRSTRT
Over
current
condtion
ILMIT
Figure 35. FLAGB Assertion in Under-Voltage Fault
Figure 36. FPF2300 FLAGB Reports While Entering
into an Over-Current Condition
Note:
6. An over-current condition signal loads the output with a
heavy load current larger than ILIM value.
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 12
FPF2300/02/03 — Dual-Output Current Limit Switch
Figure 37. FPF2300 FLAGB While and Over-Current
Condition is Applied
Note:
7. An over-current condition signal loads the output with a
heavy load current larger than ILIMIT value.
Under-Voltage Lockout (UVLO)
The under-voltage lockout feature turns off the switch if the
input voltage drops below the under-voltage lockout threshold.
With the ON pin active (ON pin pulled LOW), the input voltage
rising above the under-voltage lockout threshold causes a
controlled turn-on of the switch and limits current overshoot. If a
device is in UVLO condition, both FLAGBs go LOW and indicate
the fault condition. The device detects the UVLO condition when
input voltage goes below UVLO voltage, but remains above
1.3V (typical).
Reverse Current Blocking
Each switch of FPF2300/2/3 has an independent reverse
current blocking feature that protects input source against
current flow from output to input. For a standard USB power
design, this is an important feature that protects the USB host
from being damaged due to reverse current flow on VBUS. To
activate the reverse current blocking, the switch must be in OFF
state (ON pins inactivated) so that no current flows from the
output to the input. The FLAGB operation is independent of the
reverse current blocking and does not report a fault condition if
this feature is activated.
Thermal Shutdown
The thermal shutdown protects the device from internally or
externally generated excessive temperatures. Each switch has
an individual thermal shutdown protection function and operates
independently as adjacent switch temperatures increase above
140°C. If one switch is in normal operation and shutdown
protection of second switch is activated, the first channel
continues to operate if the affected channel's heat stays
confined. The over-temperature in one channel can shut down
both switches due to rapidly generated excessive load currents
resulting in very high power dissipation. Generally, a thermally
improved board layout can provide heat sinking and allow heat
to stay confined and not affect the second switch operation.
During an over-temperature condition, the FLAGB is pulled
LOW and the affected switch is turned off. If the temperature of
the die drops below the threshold temperature, the switch
automatically turns on again. To avoid unwanted thermal
oscillations, a 10°C (typical) thermal hysteresis is implemented
between thermal shutdown entry and exit temperatures.
If output of both switches are connected together and an
excessive load current activates thermal protection of both, the
controller can shut down the switches after both FLAGB outputs
go LOW and turn on both channels again. This provides
simultaneous switch turn on. Thermal protection is for device
protection and should not be used as regular operation.
Input Capacitor
To limit the voltage drop on the input supply caused by transient
inrush currents when the switch is turned on into discharged
load capacitors or a short-circuit; an input capacitor, CIN, is
recommended between IN and GND. The FPF2310/2/3/3L
features a fast current limit response time of 20μs. An inrush
current (also known as surge current) could occur during the
current limit response time while the switch is responding to an
over-current condition caused by large output capacitors. A
10μF ceramic capacitor, CIN, is required to provide charges for
the inrush current and prevent input voltage drop at turn on.
Higher values of CIN can be used to further reduce voltage drop.
Output Capacitor
A 0.1μF to 1μF capacitor, COUT
, should be placed between the
OUT and GND pins. This capacitor prevents parasitic board
inductances from forcing output voltage below GND when the
switch turns off. This capacitor should have a low dissipation
factor. An X7R MLCC (Multilayer Ceramic Chip) capacitors is
recommended.
For the FPF2300 and FPF2302, the total output capacitance
needs to be kept below a maximum value, COUT(MAX), to
prevent the part from registering an over-current condition
beyond the blanking time and shutdown. The maximum output
capacitance for a giving input voltage can be determined from
the following:
For example, in a 5V application, COUT(MAX) can be determined
as:
VIN
ON
FLAGB
VOUT
Star tup
tBLANK
ILOAD
ILIMIT
Over
current
condtion
Thermal Shutdown
Device Cools Off
(1)
COUT(MAX) =
ILIM(MIN) x tBLANK(MIN)
VIN
(2)
COUT(MAX)(IN = 5V) =
1.1A x 5ms
5
=1.1mF
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 13
FPF2300/02/03 — Dual-Output Current Limit Switch
Application Information
Figure 38. Self Powered 4-Port USB Hub Using a Single FPF230X
FPF230X is designed to simplify USB port power design based
on self-powering USB host/hub applications. A self-powering
USB port is powered by a local 5V power supply, not by an
upstream port. Each port should supply at least 500mA to each
downstream function based on USB 2.0 specification. Imple-
mentation can depend on the number of USB ports and current
capability per port required in actual power designs. FPF230X
has 1.1A minimum current limit per output, which can cover two
ports, as shown in Figure 38. Four USB ports can be imple-
mented with a single FPF230X part and current limiting is pro-
vided based on a two-port basis for a cost-effective solution.
Figure 39. Individual Port Power Management for Self-Powered 4-Port USB Hub
In Figure 39, each USB port is connected with each output.
Four USB ports can be implemented with two FPF230X parts.
Current limiting and control are provided based on a single port.
Current capability per port has more headroom; up to a mini-
mum of 1.1A per port.
OFF ON ONA
IN
GND
FPF2300/2/3
FLAGB(B)
OUTA
FLAGB(A)
OFF ON ONB OUTB
Host
5V
Downstream
USB Port
Downstream
USB Port
Downstream
USB Port
Downstream
USB Port
1μF
33μF
33μF
33μF
33μF
10KΩ
10KΩ
OFF ON ONA
IN
GND
FPF2300/2/3
FLAGB(B)
OUTA
FLAGB(A)
OFF ON ONB OUTB
Host
5V
Downstream
USB Port
Downstream
USB Port
1μF
33μF
33μF
10KΩ
10KΩ
OFF ON ONA
IN
GND
FPF2300/2/3
FLAGB(B)
OUTA
FLAGB(A)
OFF ON ONB OUTB
Downstream
USB Port
Downstream
USB Port
1μF
33μF
33μF
10KΩ
10KΩ
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 14
FPF2300/02/03 — Dual-Output Current Limit Switch
Figure 40. Self-Powered USB Port for High Current Demand
High current, over 2A, is sometimes required to supply enough
power to downstream functions. As shown in Figure 40, a 2.2A
minimum load current can be achieved by tying dual outputs
together.
Power Dissipation
During normal operation as a switch, the power dissipation of
the device is small and has little effect on the operating
temperature of the part. The maximum power dissipation for
both switches while the switch is in normal operation occurs just
before both channels enter into current limit. This may be
calculated using the formula:
For example, for a 5V application, maximum normal operation
power loss while both switches delivering output current up to
1.1A, can be calculated as:
The maximum junction temperature should be limited to 125°C
under normal operation. Junction temperature can be calcu-
lated using the formula below:
where:
TJ is junction temperature;
PD is power dissipation across the switch;
RθJA is thermal resistance junction to ambient of the package;
TA is ambient temperature.
For the example, TJ(MAX)(Normal operation) for an SO8 package
with TA=25°C while both switches are delivering up to 1.1A is
calculated as:
If the part goes into current limit, the maximum power
dissipation occurs when the output of switch is shorted to
ground. For the FPF2300 the power dissipation scales with the
auto-restart time, tRSTRT
, and the over-current blanking time,
tBLANK. In this case, the maximum power dissipated for the
FPF2300 is::
which results in:
Note that this is below the maximum package power dissipation
and the thermal shutdown feature protection provides additional
safety to protect the part from damage due to excessive
heating. The junction temperature is only able to increase to the
thermal shutdown threshold. Once this temperature has been
reached, toggling ON has no affect until the junction
temperature drops below the thermal shutdown exit
temperature. For the FPF2303, a short on both outputs causes
both switches to operate in a constant current state and
dissipate a worst-case power of:
As both FPF2303 outputs are connected to GND.
This power dissipation is significant and activates both thermal
shutdown blocks and the part can cycle in and out of thermal
shutdown as long as the ON pin is activated (pulled LOW) and
the output short is present.
OFF ON ONA
IN
GND
FPF2300/2/3
FLAGB(B)
OUTA
FLAGB(A)
OFF ON ONB OUTB
Host
5V
Downstream
USB Port
1μF
33μF
10KΩ
10KΩ
PD_MAX(Normal Operation) = 2 x (ILIM(MIN))
2
x RON(MAX) (3)
PD_MAX(Normal Operation)(IN = 5V) = 2 x (1.1)2 x 0.14
=338mW
(4)
TJ = PD x RθJA + TA (5)
TJ(MAX)(NormalOperation)
= PD_MAX(Normal Operation)(IN = 5V) x 125 + 25
= 78.4°C
(6)
PD_MAX(CurrentLimit) =
tBLANK
tBLANK + tRSTRT
2 x x IN(MAX) x ILIM(MAX)
(7)
PD_MAX(CurrentLimit) = 10
10 + 504
2 x (8)
x 5.5 x 1.5 = 321mW
(9)PMAX = 2 x IN(MAX) x ILIM(MAX) = 2 x 5.5 x1.5 = 16.5 W
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 15
FPF2300/02/03 — Dual-Output Current Limit Switch
PCB Layout Recommendations
For the best performance, all traces should be as short as
possible. To be most effective, the input and output capacitors
should be placed close to the device to minimize the effects that
parasitic trace inductances may have on normal and short-
circuit operation. Using wide traces for IN, OUTs, and GND pins
helps minimize parasitic electrical effects and the case-to-
ambient thermal impedance.
Improving Thermal Performance
Improper layout could result in higher junction temperature and
triggering the thermal shutdown protection feature. This concern
is particularly significant for the FPF2303, where both channels
operate in constant current mode in the overload conditions and
during fault condition the outputs are shorted, resulting in large
voltage drop across switches. In this case, power dissipation of
the switch (PD = (VIN - VOUT) x ILIM(MAX)) could exceed the
maximum absolute power dissipation of part.
The following techniques improve the thermal performance of
this family of devices. These techniques are listed in order of
the significance of impact.
1. Thermal performance of the load switch can be improved
by connecting the DAP (Die Attach Pad) of MLP 3x3mm
package to the GND plane of the PCB.
2. Embedding two exposed through-hole vias into the DAP
(pin 9) provides a path for heat to transfer to the back GND
plane of the PCB. A drill size of round, 15 mils (0.4mm),
with 1-ounce copper plating is recommended to create
appropriate solder reflow. A smaller size hole prevents the
solder from penetrating into the via, resulting in device lift-
up. Similarly, a larger via hole consumes excessive solder
and may result in voiding of the DAP.
Figure 41. Two Through-Hole Open Vias Embedded
in DAP
3. The IN, OUTs, and GND pins dissipate most of the heat
generated during a high load current condition. Figure 42
illustrates a proper layout for devices in MLP 3x3mm
packages. IN, OUTs, and GND pins are connected to
adequate copper so heat may be transferred as efficiently
as possible out of the device. The low-power FLAGB and
ON pin traces may be laid out diagonally from the device to
maximize the area available to the ground pad. Placing the
input and output capacitors as close to the device as
possible also contributes to heat dissipation, particularly
during high load currents.
Figure 42. Proper Layout of Output and Ground
Copper Area
15mil
25mil
© 2009 Fairchild Semiconductor Corporation www.fairchildsemi.com
FPF2300/02/03 • Rev. 1.1.3 16
FPF2300/02/03 — Dual-Output Current Limit Switch
FPF230X Evaluation Board
The FPF230X evaluation board has components and circuitry to
demonstrate FPF2300/2/3 load switch functions and features,
accommodating both the MLP 3x3mm and SO8 packages. The
state of the each channel can be configured using J1 and J2
jumpers. In addition, both channels can be controlled by ONA
and ONB test pints. Thermal performance of the board is
improved using techniques in the layout recommendations
section. R3 and R4 resistors are used on the board to sink a
light load current when switches are activated.
Figure 43. Top, SST and AST Layers
(MLP 3x3mm and SO8)
Figure 44. Bottom and ASB Layers
Figure 45. Zoom-In to Top Layer
Releated Resources
FPF2300/02/03 Evaluation Board User Guide; Power Switch for USB Applications
NOTES:
A. CONFORMS TO JEDEC REGISTRATION MO-229,
VARIATION VEEC, DATED 11/2001.
B. DIMENSIONS ARE IN MILLIMETERS.
C. DIMENSIONS AND TOLERANCES PER
ASME Y14.5M, 2009.
D. LAND PATTERN RECOMMENDATION IS
EXISTING INDUSTRY LAND PATTERN.
E. DRAWING FILENAME: MKT-MLP08Drev3
0.10 C A B
0.05 C
TOP VIEW
BOTTOM VIEW
RECOMMENDED LAND PATTERN
0.10 C
0.08 C
3.00
3.00
0.10 C
2X
2X
SEATING
PLANE
0.10 C (0.20)
1.99
3.30
(0.65)
14
5
8
5
8
4
1
0.65 1.95
0.65 TYP
2.37
1.42
0.42 TYP
PIN #1 IDENT
AB
0.80 MAX
0.05
0.00 C
FRONT VIEW
2.25MAX
PIN #1 IDENT
1.30MAX
0.45
0.20
0.25
0.35
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