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FPF2300/02/03 -- Dual-Output Current Limit Switch
June 2009
FPF2300/02/03 Dual-Output Current Limit Switch
Features
! 1.8 to 5.5V Input Voltage Range ! Typical RON = 75m 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
Description
The FPF2300/02/03 are dual-channel load switches of IntelliMAXTM family. The FPF2300/02/03 consist of dual, independent, current-limited, slew rate controlled, Pchannel 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 persists 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.
Applications
! Notebook Computing ! Peripheral USB Ports ! Networking / USB Based Equiptment
Figure 1. 8-Lead SOP
Figure 2. 8-Lead MLP (3x3mm)
Ordering Information
Part Number
FPF2300MX FPF2302MX FPF2303MX FPF2300MPX FPF2302MPX FPF2303MPX
Minimum Current Limit Current Blanking Time Eco Limit Status
1100mA 1100mA 1100mA 1100mA 1100mA 1100mA 10ms 10ms 0ms 10ms 10ms 0ms RoHS RoHS RoHS Green Green Green
Auto Restart
504ms N/A N/A 504 N/A N/A
ON Pin Activity
Active LOW Active LOW Active LOW Active LOW Active LOW Active LOW
Mode
Restart
Package
8-Lead SO8
Latch Off 8-Lead SO8 Constant 8-Lead SO8 Current Restart Latch Off 8-Lead Molded Leadless Package (MLP) 8-Lead Molded Leadless Package (MLP)
Constant 8-Lead Molded LeadCurrent less Package (MLP)
For Fairchild's definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Application Circuit
IN
FLAGB(A) FLAGB(B)
IN = 1.8V-5.5V
CIN
OFF ON OFF ON
FPF2300/2/3
ONA ONB GND OUTA OUTB COUTB TO LOAD A TO LOAD B COUTA
Figure 3. Typical Application
Functional Block Diagram
IN
UVLO
ONA
CONTROL LOGIC A
REVERSE CURRENT BLOCKING
CURRENT LIMIT A THERMAL PROTECTION A
OUTA
FLAGB(A)
ONB
CONTROL LOGIC B
REVERSE CURRENT BLOCKING
CURRENT LIMIT B THERMAL PROTECTION B
OUTB FLAGB(B)
GND
Figure 4. Block Diagram
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 2 www.fairchildsemi.com
FPF2300/02/03 -- Dual-Output Current Limit Switch
Pin Configuration
GND IN ONA ONB
1 2 3 4 SO8
8 7 6 5
FLAGB(A) OUTA OUTB FLAGB(B)
FLAGB(A) OUTA OUTB FLAGB(B)
8 7 9 6 5
1 2 3
GND IN ONA
4 ONB
MLP 3X3mm 8-Lead Bottom View
Figure 5. Pin Configurations
Pin Description
Pin #
1 2 3 4 5 6 7 8 9(MLP)
Name
GND IN ONA ONB FLAGB(B) OUTB OUTA FLAGB(A) Thermal Pad Ground
Function
Supply Input: Input to the power switch and the supply voltage for the IC. ON / OFF control input of power switch A. Active LOW ON / OFF control input of power switch B. Active LOW Fault Output B, Active LO, open drain output which indicates an over supply, UVLO and thermal shutdown. Switch Output: Output of the power switch B Switch Output: Output of the power switch A Fault Output A, Active LO, open drain output which indicates an over supply, UVLO and thermal shutdown. IC Substrate, which can be connected to GND for better thermal performance. Do not connect to other pins.
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 3
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only.
Symbol
Parameter
IN, OUTA, OUTB, ONA, ONB, FLAGB(A), FLAGB(B) to GND SO8
Min.
-0.3
Max.
6.0 0.8(1) 1.4(2) 0.6(3) 2.2(4)
Unit
V
PD
Power Dissipation MLP
W
TSTG
Storage Temperature SO8
-65
+150 158(1) 92(2) 216(3) 57(4)
C
JA
Thermal Resistance, Junction-to-Ambient MLP
C/W
ESD
Electrostatic Discharge Protection
Human Body Model, JESD22-A114 Charged Device Model, JESD22-C101
4000 2000
V
Notes: 1. Two-layer PCB of 2s0p from JEDEC STD 51-3. 2. 3. 4. Four-layer PBD of 2s0p from JEDEC STD 51-7. Soldered thermal pad on a two-layer PCB without vias based on JEDEC STD 51-3. 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
IN TA
Parameter
Supply Input Ambient Operating Temperature
Min.
1.8 -40
Max.
5.5 +85
Unit
V C
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 4
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Electrical Characteristics
IN = 1.8 to 5.5V, TA = -40 to +85C unless otherwise noted. Typical values are at IN = 3.3V and TA = 25C.
Symbol
VIN IQ ISD RON VIH VIL ION
Parameter
Operating Voltage Quiescent Current IN Shutdown Current On Resistance ON Input Logic High Voltage (ON) ON Input Logic Low Voltage ON Input Leakage FLAGB Output Logic Low Voltage FLAGB Output High Leakage Current
Conditions
Min. Typ. Max. Units
1.8 5.5 52.5 94.5 3 75 90 0.8 1.4 0.5 0.9 -1 0.1 0.15 1 0.2 0.30 1 1.1 1.3 140 130 10 1.55 1.65 50 1.75 V mV s s s 20 20 ms ms ms s C 1.5 140 V A A m V V A V A A
Basic Operation IN = 5.5V, VONA = VONB = 0V, IOUT = 0mA VONA = VONB = 5.5V, IN = 5.5V OUTA = OUTB = Short to GND, IN = 5.5V, IOUT = 200mA, TA = 25C IN = 5.5V, IOUT = 200mA, TA = -40C to 85C IN = 1.8V IN = 5.5V IN = 1.8V IN = 5.5V VON = IN or GND IN = 5.5V, ISINK = 1mA IN = 1.8V, ISINK = 1mA IN = VON = 5V IN = 3.3V, VOUTA = VOUTB = 3V, TA = 25C Shutdown Threshold TSD VUVLO VUVLO_HYS Dynamic tON tOFF tR tBLANK tRSRT tCLR Turn-On Time Turn-Off Time OUTA, OUTB Rise Time Over-Current Blanking Time Auto-Restart Time Current Limit Response Time RL = 500, CL = 0.1F RL = 500 RL = 500, CL = 0.1F FPF2300, FPF2302 FPF2303(5) FPF2300 IN = 3.3V, Moderate Over-Current Condition 5 5 113.5 6 13.5 10 10 504 20 Thermal Shutdown Under-Voltage Shutdown Under-Voltage Shutdown Hysteresis Return from Shutdown Hysteresis IN Increasing
Protections ILIM Current Limit
tRSTRT_BLANK Startup FLAGB Blanking Time
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. OUT
90% 10% 90% 10%
tR ON
50%
tF
50%
OUT tDON
90% 10%
tDOFF tOFF = tF + tDOFF
tON = tR + tDON
Figure 6. Timing Diagram
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 5 www.fairchildsemi.com
FPF2300/02/03 -- Dual-Output Current Limit Switch
Typical Characteristics
70.00 O A = O B = 0V N N 60.00 SUPPLY CURRENT (uA) 85C 25C -40C 50.00 40.00 30.00 20.00 10.00 0.00 1.8
70.00 O = O = 0V NA NB 60.00 IQ CURRENT (uA) 50.00 40.00 30.00 20.00 10.00 IN = 3.3V IN = 1.8V IN = 5.5V
2.2
2.5
2.9
3.3
3.7
4.0
4.4
4.8
5.1
5.5
SU PPLY VO LTA E (V) G
0.00 -40
-15
10
35
60
85
TJ, JUNCTION TEM PERA TURE (C)
Figure 7. Quiescent Current vs. Supply Voltage
Figure 8. Quiescent Current vs. Temperature
5.00 IN SHUTDOWN CURRENT (uA) 4.50 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 -40 -15 10 35 60 85 IN = O = O = 5.5V NA NB O = 0V UT
160 150 ON RESISTANCE (mOhms) 140 130 120 110 100 90 80 70 60 1.8 2.2 2.5 2.9 3.3 3.7 4.0 4.4 4.8 5.1 5.5 RON A RON B ONA = O = 0V NB IOUT = 200m A TA = 25C
TJ, JUNCTIO TEM N PERA TURE (C)
SUPPLY VOLTA (V) GE
Figure 9. IN Shutdown Current vs. Temperature
Figure 10. RON vs. Supply Voltage (MLP)
160 150 ON RESISTANCE (mOhms) 140 130 120 110 100 90 80 70 60 1.8 2.2 2.5 2.9 RON A RON B ONA = O = 0V NB IOUT = 200m A TA = 25C
100 95 ON RESISTANCE (mOhm) 90 85 80 75 70 65 60 55 RON B RON A IN = 5.5V IOUT = 200m A O = O = 0V NA NB
3.3
3.7
4.0
4.4
4.8
5.1
5.5
50 -40
-15
10
35
60
85
SUPPLY VOLTA (V) GE
TJ, JUNCTIO TEM N PERA TURE (C)
Figure 11. RON vs. Temperature (SO8)
Figure 12. RON vs. Temperature (MLP)
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 6
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Typical Characteristics
90 85 ON RESISTANCE (mOhm) 80 75 70 65 60 55 50 -40 RON B
ON THRESHOLD VOLTAGE (V)
IN = 5.5V IOUT = 200m A ONA = O = 0V NB
1.5 TA = 25C 1.3 1.0 0.8 0.5 0.3 0.0 VIL
VIH
RON A
-15
10
35
60
85
1.8
2.2
2.5
2.9
3.3
3.7
4.0
4.4
4.8
5.1
5.5
TJ, JUNCTIO TEM N PERA TURE (C)
SUPPLY VO G (V) LTA E
Figure 13. RON vs. Temperature (SO8)
Figure 14. ON Threshold Voltage vs. Supply Voltage
1.2 ON THRESHOLD VOLTAGE (V)
ON THRESHOLD VOLTAGE (V)
1.2
IN = 5.5V 1.0 IN = 3.3V 0.8 IN = 1.8V 0.6 0.4 0.2 0.0 -40
IN = 5.5V 1.0 0.8 0.6 IN = 1.8V 0.4 0.2 0.0 -40 IN = 3.3V
-15
10
35
60
85
-15
10
35
60
85
TJ, JUNCTIO TEM N PERA TURE (C)
TJ, JUNCTIO TEM N PERA TURE (C)
Figure 15. ON High Voltage vs. Temperature
Figure 16. ON Low Voltage vs. Temperature
1350 1340 CURRENT LIMIT (mA) 1330 1320 1310 1300 1290 1280 1270 1260
TA = 25C
1350
ILIM (Typ)A ILIM (Typ)B
CURRENT LIMIT (mA)
IN = 3.3V 1340 O UTA = O UTB = 3V NA NB 1330 O = O = 0V 1320 1310 1300 1290 1280 1270 1260 ILIM (Typ)A
ILIM (Typ)B
1250 1.8
2.2
2.5
2.9
3.3
3.7
4.0
4.4
4.8
5.1
5.5
1250 -40
-15
10
35
60
85
SUPPLY VO G (V) LTA E
TJ, JUNCTIO TEM N PERA TURE (C)
Figure 17. Current Limit vs. Supply Voltage
Figure 18. Current Limit vs. Temperature
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Typical Characteristics
1000 TURN ON/OFF DELAY TIME (us) IN = 3.3V hm RL = 500 O s CL = 0.1 uF 20 18 16 RISE/FALL TIME (us) 14 12 10 8 6 4 2 1 -40 -15 10 35 60 85 0 -40 -15 10 35 60 85 tF IN = 3.3V RL = 500 O s hm tR IN = 3.3V RL = 500 O s hm CL = 0.1 uF
tDON 100
10 tDOFF
IN = 3.3V hm RL = 500 O s
TJ, JUNCTIO TEM N PERA TURE (C)
TJ, JUNCTIO TEM N PERA TURE (C)
Figure 19. tDON / tDOFF vs. Temperature
Figure 20. tRISE / tFALL vs. Temperature
OVER CURRENT BLANKING TIME (ms)
STARTUP FLAGB BLANKING TIME (ms)
11.0 10.5 10.0
10.0 9.5 9.0
FPF2300/2 IN = 3.3V O = O = 0V NA NB FLAG B(B)
FPF2303 IN = 3.3V O = O = 0V NA NB
9.5 FLAG B(A) 9.0 8.5 8.0 7.5 7.0 -40
FLAG B(A) 8.5 FLAG B(B) 8.0 7.5 7.0 -40
-15
10
35
60
85
-15
10
35
60
85
TJ, JUNCTIO TEM N PERA TURE (C)
TJ, JUNCTIO TEM N PERA TURE (C)
Figure 21. tBLANK vs. Temperature
Figure 22. tRSTRT_BLANK vs. Temperature
620.0 600.0 RESTART TIME (ms) 580.0 O UTA 560.0 540.0 OUTB 520.0 500.0 -40 FPF2300 IN = 3.3V O = O = 0V NA NB
IN 2V/DIV ON 2V/DIV IN = 5V ON = 3.3V COUT = 0.1F RL = 500 200s/DIV
OUT 2V/DIV
-15 10 35 60 85
TJ, JUNCTIO TEM N PERA TURE (C)
Figure 23. tRSTRT vs. Temperature
Figure 24. tON Response
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 8
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Typical Characteristics
IN = 5V COUT = 10F RL = 2.8 tBLANK
IN 2V/DIV ON 2V/DIV IN = 5V ON = 3.3V COUT = 0.1F RL = 500 200s/DIV
ON 2V/DIV FLAGB 2V/DIV IOUT 1A/DIV OUT 5V/DIV
OUT 2V/DIV
2ms/DIV
Figure 25. tOFF Response
Figure 26. Over-Current Blanking Time (FPF2300/2)
ON 2V/DIV FLAGB 2V/DIV IOUT 1A/DIV OUT 2V/DIV
COUT = 10F RL = 3.3 tSTART_BLANK
ON 2V/DIV FLAGB 2V/DIV IOUT 1A/DIV OUT 5V/DIV
tRSTRT
IN = 5V COUT = 10F RL = 2.8 100ms/DIV
2ms/DIV
Figure 27. Startup FLAGB Blanking Time (FPF2303)
Figure 28. Auto-Restart Time (FPF2300)
IN 5V/DIV ON 5V/DIV IOUT 1A/DIV
IN = 5V ON = 3.3V RL = 5 COUT = 470F
IN 5V/DIV ON 5V/DIV OUT 5V/DIV COUT = 47F COUT = 100F
IN = 5V ON = 3.3V RL = 5
COUT = 220F COUT = 470F
COUT = 220F COUT = 100F COUT = 47F 200s/DIV
200s/DIV
Figure 29. Current Limit at Startup with Different Output Capacitor
Figure 30. Output Voltage at Startup with Different Output Capacitor
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 9
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Typical Characteristics
IN 5V/DIV ON 2V/DIV OUTA 2V/DIV OUTB 2V/DIV 400s/DIV IN = 5V ON = 3.3V COUTA = 100F COUTB = 100F RLA = RLB = 1 IN 5V/DIV ON 2V/DIV FLAGB(A) 2V/DIV FLAGB(B) 2V/DIV 10ms/DIV IN = 5V ON = 3.3V COUTA = 100F COUTB = 100F RLA = RLB = 1
Figure 31. Current Limit Response Time Both Channels are in OC
Figure 32. Startup FLAGB Blanking Time
IN 5V/DIV ON 5V/DIV IOUT 500mA/DIV OUT 5V/DIV 1ms/DIV
IN = 5V COUT = 47F CL = 470F RL = 5
IN 5V/DIV ON 5V/DIV IOUT 2A/DIV OUT 5V/DIV 200s/DIV
IN = 5V CIN = 10F COUT = 100F CL = 47F
Figure 33. Inrush Response During Capacitive Load Hot Plug-In Event
Figure 34. Inrush Response During Capacitive and Resistive Load Hot Plug-In Event
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 10
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Description of Operation
The FPF2300, FPF2302, and FPF2303 are dual-output currentlimit 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 75m (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. startup blanking feature that prevents current faults related to startup transients from triggering the FLAGB output. The startup blanking 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 100K pull-up resistor is recommended. When the ON pin is inactive, 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. . ON
device wakeup
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 140C 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.
IN FLAGB
device wakeup
RISE TIME
90% VOUT
OUT ILOAD
10% VOUT
ILIMIT
Figure 35. FLAGB Assertion in Under-Voltage Fault
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.
ON
VIN
VOUT ILOAD
RL ILMIT *
ILIMIT
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
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 11
condtion
FLAGB
tBLANK
Over current
tRSTRT
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.
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FPF2300/02/03 -- Dual-Output Current Limit Switch
ON
automatically turns on again. To avoid unwanted thermal oscillations, a 10C (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.
VIN
VOUT ILOAD
ILIMIT
Therm
al Sh
wn utdo
Dev
ice Co
ols
Off
Over current condtion
Input Capacitor
Startup tBLANK
FLAGB
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).
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 20s. 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 10F 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 0.1F to 1F 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: ILIM(MIN) x tBLANK(MIN) (1) COUT(MAX) = VIN For example, in a 5V application, COUT(MAX) can be determined as: 1.1A x 5ms (2) COUT(MAX)(IN = 5V) = 5 = 1.1mF
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 140C. 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
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Application Information
10K 10K 33F Downstream USB Port Downstream USB Port
Host 5V
1F OFF ON OFF ON
IN
FLAGB(A) FLAGB(B)
FPF2300/2/3
ONA ONB GND OUTA OUTB
33F
33F
Downstream USB Port Downstream USB Port
33F
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. Implementation 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 implemented with a single FPF230X part and current limiting is provided based on a two-port basis for a cost-effective solution.
10K 10K
Host 5V
1F OFF ON OFF ON
IN
FLAGB(A) FLAGB(B)
FPF2300/2/3
ONA ONB GND OUTA OUTB
33F
Downstream USB Port
33F 10K 10K
Downstream USB Port
IN
FLAGB(A) FLAGB(B)
FPF2300/2/3
1F OFF ON OFF ON ONA ONB GND OUTA OUTB
33F
Downstream USB Port
33F
Downstream USB Port
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 minimum of 1.1A per port.
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 13
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FPF2300/02/03 -- Dual-Output Current Limit Switch
10K 10K
Host 5V
1F OFF ON OFF ON
IN
FLAGB(A) FLAGB(B)
FPF2300/2/3
ONA ONB GND OUTA OUTB 33F Downstream USB Port
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: PD_MAX(Normal Operation) = 2 x (ILIM(MIN))2 x RON(MAX) (3) 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: PD_MAX(Normal Operation)(IN = 5V) = 2 x (1.1) x 0.14 = 338mW
2
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:: tBLANK x IN(MAX) x ILIM(MAX) PD_MAX(CurrentLimit) = 2 x tBLANK + tRSTRT (7) which results in: PD_MAX(CurrentLimit) = 2 x 10 x 5.5 x 1.5 = 321mW (8) 10 + 504
(4)
The maximum junction temperature should be limited to 125C under normal operation. Junction temperature can be calculated using the formula below: TJ = PD x RJA + TA where: TJ is junction temperature; PD is power dissipation across the switch; RJA 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=25C while both switches are delivering up to 1.1A is calculated as: TJ(MAX)(NormalOperation) (6) x 125 + 25 =P
D_MAX(Normal Operation)(IN = 5V)
(5)
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: PMAX = 2 x IN(MAX) x ILIM(MAX) = 2 x 5.5 x1.5 = 16.5 W (9) 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.
= 78.4C
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 14
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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 shortcircuit operation. Using wide traces for IN, OUTs, and GND pins helps minimize parasitic electrical effects and the case-toambient 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. 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 liftup. Similarly, a larger via hole consumes excessive solder and may result in voiding of the DAP.
Figure 42. Proper Layout of Output and Ground Copper Area
2.
15mil
25mil
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.
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 15
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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 44. Bottom and ASB Layers
Figure 43. Top, SST and AST Layers (MLP 3x3mm and SO8)
Figure 45. Zoom-In to Top Layer
Releated Resources
FPF2300/02/03 Evaluation Board User Guide; Power Switch for USB Applications
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 16
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Dimensional Outline and Pad Layout
Figure 46. 8-Lead SO8 Package
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild's worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor's online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/.
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 17
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FPF2300/02/03 -- Dual-Output Current Limit Switch
Dimensional Outline and Pad Layout
Figure 47. 8-Lead Molded Leadless Package (MLP)
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild's worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor's online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/.
(c) 2009 Fairchild Semiconductor Corporation FPF2300/02/03 * Rev. 1.1.3 18
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FPF2300/02/03 -- Dual-Output Current Limit Switch
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