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FPF2148 Full Function Load Switch
July 2007
FPF2148 Full Function Load Switch
Features
1.8 to 5.5V Input Voltage Range Controlled Turn-On 200mA Current Limit Options Undervoltage Lockout Thermal Shutdown <2A Shutdown Current Fast Current limit Response Time 5s to Moderate Over Currents 30ns to Hard Shorts Fault Blanking Power Good Function RoHS Compliant
tm
General Description
The FPF2148 is a load switch which provides full protection to systems and loads which may encounter large current conditions. These devices contain a 0.15 current-limited P-channel MOSFET which can operate over an input voltage range of 1.8-5.5V. Switch control is by a logic input (ONB) capable of interfacing directly with low voltage control signals. The part contains thermal shutdown protection which shuts off the switch to prevent damage to the part when a continuous over-current condition causes excessive heating. When the switch current reaches the current limit, the part operates in a constant-current mode to prohibit excessive currents from causing damage. For the FPF2148, a current limit condition will immediately pull the fault signal pin low and the part will remain in the constant-current mode until the switch current falls below the current limit. The minimum current limit is 200mA. The part is available in a space-saving 6 pin 2X2 MLP package.
Applications
PDAs Cell Phones GPS Devices MP3 Players Digital Cameras Peripheral Ports Hot Swap Supplies
Pin 1 BOTTOM TOP
Ordering Information
Part
FPF2148
Current Limit [mA]
200/300/400
Current Limit Blanking Time [ms]
NA
Auto-Restart Time [ms]
NA
ONB Pin Activity
Active LO
(c)2007 Fairchild Semiconductor Corporation
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FPF2148 Rev. B3
FPF2148 Full Function Load Switch
Typical Application Circuit
TO LOAD VOUT
VIN
FPF2148
PGOOD ON OFF ONB GND FLAGB
Functional Block Diagram
VIN
UVLO
ONB THERMAL SHUTDOWN
CONTROL LOGIC
REVERSE CURRENT BLOCKING
CURRENT LIMIT
VOUT
FLAGB PGOOD
GND
FPF2148 Rev. B3
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FPF2148 Full Function Load Switch
Pin Configuration
ONB GND FLAGB 6 5 4 1 2 3 PGOOD VIN VOUT
2X2 MicroFET-6
Pin Description
Pin
1 2 3 4 5 6
Name
PGOOD VIN VOUT FLAGB GND ONB
Function
Power Good output: Open drain output which indicate that output voltage has reached 90% of input voltage Supply Input: Input to the power switch and the supply voltage For the IC Switch Output: Output of the power switch Fault Output: Active LO, open drain output which indicates an over current supply under voltage or over temperature state. Ground ON Control Input
Absolute Maximum Ratings
Parameter
VIN, VOUT, ONB, FLAGB, PGOOD to GND Power Dissipation Operating and Storage Junction Temperature Thermal Resistance, Junction to Ambient Electrostatic Discharge Protection HBM MM 4000 400 -65
Min.
-0.3
Max.
6 1.2 150 86
Unit
V W C C/W V V
Recommended Operating Range
Parameter
VIN Ambient Operating Temperature, TA
Min.
1.8 -40
Max.
5.5 85
Unit
V C
Electrical Characteristics
VIN = 1.8 to 5.5V, TA = -40 to +85C unless otherwise noted. Typical values are at VIN = 3.3V and TA = 25C.
Parameter
Basic Operation Operating Voltage Quiescent Current
Symbol
VIN
Conditions
Min.
1.8
Typ.
Max.
5.5
Units
V A
VIN = 1.8V IQ IOUT = 0mA VIN = 3.3V VIN = 5.5V On-Resistance RON TA = 25C, IOUT = 200mA TA = -40 to +85C, IOUT = 200mA
40
70 75 85 120 135
100 120 160 m
FPF2148 Rev. B3
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FPF2148 Full Function Load Switch
Electrical Characteristics Cont.
VIN = 1.8 to 5.5V, TA = -40 to +85C unless otherwise noted. Typical values are at VIN = 3.3V and TA = 25C.
Parameter
ONB Input Logic High Voltage (ON) ONB Input Logic Low Voltage ONB Input Leakage VIN Shutdown Current FLAGB Output Logic Low Voltage FLAGB Output High Leakage Current PGOOD Threshold Voltage PGOOD Threshold Voltage Hysteresis PGOOD Output Logic Low Voltage PGOOD Output High Leakage Current Reverse Block VOUT Shutdown Current Protections Current Limit Thermal Shutdown Under Voltage Lockout Under Voltage Lockout Hysteresis Dynamic Turn on time Turn off time VOUT Rise Time VOUT Fall Time Short Circuit Response Time
Symbol
VIH VIL VIN = 1.8V VIN = 5.5V VIN = 1.8V VIN = 5.5V
Conditions
Min.
0.8 1.4
Typ.
Max.
Units
V
0.5 1 -1 -2 0.05 0.12 90 1 1 2 0.2 0.3 1
V A A V A % %
VONB = VIN or GND VONB = 5.5V, VOUT = 5.5V, VIN = short to GND VIN = 5V, ISINK = 10mA VIN = 1.8V, ISINK = 10mA VIN = 5V, VONB = 0V VIN = 5.5V
VIN = 5V, ISINK = 10mA VIN = 1.8V, ISINK = 10mA VIN = 5V, VONB = 0V
0.05 0.12
0.1 0.2 1
V V A
VONB = 5.5V, VOUT = 5.5V, VIN = short to GND ILIM VIN = 3.3V, VOUT = 3.0V Shutdown Threshold TJ increasing Return from Shutdown Hysteresis VUVLO VIN Increasing
-2
2
A
200
300 140 130 10
400
mA C
1.55
1.65 50
1.75
V mV s s s s s ns
tON tOFF tR tF
RL=500, CL=0.1F RL=500, CL=0.1F RL=500, CL=0.1F RL=500, CL=0.1F VIN = 5.5V, VONB = GND. Moderate Over-Current Condition VIN = 5.5V, VONB = GND. Hard Short
25 45 10 110 5 30
Note 1: Package power dissipation on 1square inch pad, 2 oz. copper board.
FPF2148 Rev. B3
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FPF2148 Full Function Load Switch
Typical Characteristics
90 85 SUPPLY CURRENT (uA)
SUPPLY CURRENT (uA) 110 105 100 95 90 85 80 75 70 65 60 55 50
VIN = 1.8V VIN = 5.5V VIN = 3.3V
80 75 70 65 60 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 SUPPLY VOLTAGE (V)
-40
-15
10
35
60
85
TJ, JUNCTION TEMPERATURE (C)
Figure 1. Quiescent Current vs. Input Voltage
Figure 2. Quiescent Current vs. Temperature
1.3
1.2 1.1 VONB LOW VOLTAGE (V) 1 0.9 0.8 0.7 0.6 0.5
1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
1.2 VONB HIGH VOLTAGE (V) 1.1 1 0.9 0.8 0.7 0.6 SUPPLY VOLTAGE (V)
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
SUPPLY VOLTAGE (V)
Figure 3. VONB High Voltage vs. Input Voltage
Figure 4. VONB Low Voltage vs. Input Voltage
200 190 180 R(ON) (mOhms) 160 150 140 130 120 110 100 90 80 1 2 3 4 5 6 VIN, SUPPLY VOLTAGE (V)
R(ON) (mOhms)
240 220 200 180 160 140 120 100 80 60 -40 -15 10 35 60 85 TJ, JUNCTION TEMPERATURE (C)
VIN = 5.5V VIN = 3.3V VIN = 1.8V
170
Figure 5. R(ON) vs. VIN
Figure 6. R(ON) vs. Temperature
FPF2148 Rev. B3
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FPF2148 Full Function Load Switch
Typical Characteristics
350
VIN = 5.5V
320 315 310 305 300 295 290
0 1 2 3 VIN - VOUT (V) 4 5 6
OUTPUT CURRENT (mA)
250 200 150 100 50 0
SUPPLY CURRENT ( mA)
300
-65
-40
-15
10
35
60
85
110
135
TJ, JUNCTION TEMPERATURE (C)
Figure 7. Current Limit vs. Output Voltage
Figure 8. Current Limit vs. Temperature
100
TURN-ON/OFF TIMES (uS)
TURN-ON/OFF TIMES (uS)
VIN = 3.3 V RL = 500 Ohms COUT = 0.1uF TOFF
1000
VIN = 3.3 V RL = 500 Ohms TF
100
TON
10
TR
10 -40 -15 10 35 60 85 TJ, JUNCTION TEMPERATURE (C)
1 -40 -15 10 35 60 85 TJ, JUNCTION TEMPERATURE (C)
Figure 9. TON / TOFF vs. Temperature
Figure 10. TRISE / TFALL vs. Temperature
VONB 2V/DIV
CIN = 10F COUT = 0.1F RL = 500 VIN = 3.3V
VONB 2V/DIV
IOUT 10mA/DIV
IOUT 10mA/DIV CIN = 10F COUT = 0.1F RL = 500 VIN = 3.3V 100s/DIV Figure 11. TON Response 1s/DIV Figure 12. TOFF Response
VOUT 2V/DIV
FPF2148 Rev. B3
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FPF2148 Full Function Load Switch
Typical Characteristics
VIN 2V/DIV IOUT 5A/DIV VOUT 2V/DIV CIN = 10F VIN = 3.3V 50s/DIV Figure 13. Short Circuit Response Time (Output shorted to GND)
VIN 2V/DIV VONB 2V/DIV IOUT 200mA/DIV VOUT 2V/DIV CIN = 10F VOUT = VONB = GND 50s/DIV Figure 14. Current Limit Response Time (Switch is powered into a short)
VIN 2V/DIV VONB 2V/DIV IOUT 200mA/DIV VOUT 2V/DIV 50s/DIV
CIN = 10F VIN = 3.3V
VIN 2V/DIV VONB 2V/DIV
CIN = 10F VIN = 3.3V
IOUT 200mA/DIV VOUT 2V/DIV 50s/DIV Figure 16. Current Limit Response Time (Output is loaded by 2.2, COUT = 10F)
Figure 15. Current Limit Response Time (Output is loaded by 2.2, COUT = 0.1F)
VIN 5V/DIV VONB 5V/DIV VOUT 5V/DIV PGOOD 5V/DIV 10s/DIV
CIN = 10F COUT = 0.1F RL = 500 VIN = 5.5V
Figure 17. PGOOD Response
FPF2148 Rev. B3
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FPF2148 Full Function Load Switch
Description of Operation
The FPF2148 is a current limited switch that protects systems and loads which can be damaged or disrupted by the application of high currents. The core of each device is a 0.15 P-channel MOSFET and a controller capable of functioning over a wide input operating range of 1.8-5.5V. The controller protects against system malfunctions through current limiting, undervoltage lockout and thermal shutdown and power good features. The current limit is preset for 200mA.
Current Limiting
The current limit ensures that the current through the switch doesn't exceed 400mA while not limiting at less than 200mA. The FPF2148 have no current limit blanking period so immediately upon a current limit condition FLAGB is activated. The part will remain in a constant current state until the ONB pin is deactivated or the thermal shutdown turns-off the switch.
Under-Voltage Lockout On/Off Control
The ONB pin controls the state of the switch. Activating ONB continuously (ONB pin low) holds the switch in the on state so long as there is no under-voltage on VIN or a junction temperature in excess of 140C. ONB is active LO and has a low threshold making it capable of interfacing with low voltage signals. In addition, excessive currents will cause the switch to turn off due to thermal shutdown. The FPF2148 does not turn off in response to a over current condition but instead remain operating in a constant current mode so long as ONB is active and the thermal shutdown or under-voltage lockout have not activated. The under-voltage lockout turns-off the switch if the input voltage drops below the under-voltage lockout threshold. With the ONB pin active the input voltage rising above the undervoltage lockout threshold will cause a controlled turn-on of the switch which limits current over-shoots.
Thermal Shutdown
The thermal shutdown protects the die from internally or externally generated excessive temperatures. During an overtemperature condition the FLAGB is activated and the switch is turned-off. The switch automatically turns-on again if temperature of the die drops below the threshold temperature.
Fault Reporting
Upon the detection of an over-current, an input under-voltage, or an over-temperature condition, the FLAGB signals the fault mode by activating LO. And the FLAGB goes LO immediately. It will remain LO during the faults and immediately returns HI at the end of the fault condition. FLAGB is an open-drain output which requires a pull-up resistor between VIN and FLAGB. During shutdown, the pull-down on FLAGB is disabled to reduce current draw from the supply.
Power Good
The PGOOD monitors the output voltage of the switch. When the ONB pin is active, PGOOD signal goes low as soon as VOUT falls below 90% of VIN. PGOOD is an open-drain output which requires a pull-up resistor between VIN and PGOOD.
FPF2148 Rev. B3
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FPF2148 Full Function Load Switch
Application Information
Typical Application
VIN Typical value = 100K Battery 1.8V-5.5V ON C1 = 0.1F OFF
VOUT
LOAD R1 = 100K R2 = 499 C2 = 0.1F
FPF2148
PGOOD ONB GND FLAGB
Input Capacitor
To limit the voltage drop on the input supply caused by transient in-rush currents when the switch turns-on into a discharged load capacitor or a short-circuit, a capacitor needs to be placed between VIN and GND. A 1F ceramic capacitor, CIN, placed close to the pins is usually sufficient. Higher values of CIN can be used to further reduce the voltage drop.
Board Layout
For 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 VIN, VOUT and GND will help minimize parasitic electrical effects along with minimizing the case to ambient thermal impedance.
Output Capacitor
A 0.1F capacitor COUT, should be placed between VOUT and GND. This capacitor will prevent parasitic board inductances from forcing VOUT below GND when the switch turns-off. For the FPF2148, the total output capacitance needs to be kept below a maximum value, COUT(max), to prevent the part from registering an over-current condition and turning-off the switch. The maximum output capacitance can be determined from the following formula, I LIM ( max ) x t R ( max ) C OUT ( max ) = ----------------------------------------------------------V IN (1)
Power Dissipation
During normal operation as a switch, the power dissipation is small and has little effect on the operating temperature of the part. The parts with the higher current limits will dissipate the most power and that will only be, 2 2 (2) P = ( I LIM ) x R DS = ( 0.4 ) x 0.15 = 24mW If the part goes into current limit the maximum power dissipation will occur when the output is shorted to ground. For the FPF2148, a short on the output will cause the part to operate in a constant current state dissipating a worst case power as calculated in (3) until the thermal shutdown activates. It will then cycle in and out of thermal shutdown so long as the ONB pin is active and the short is present. P ( max ) = V IN ( max ) x I LIM ( max )
= 5.5 x 0.4 = 275mW
(3)
FPF2148 Rev. B3
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FPF2148 Full Function Load Switch
Application Notes
Startup Power Sequence
VIN1 VIN1 ON OFF 100K PGOOD ONB FLAGB GND
FPF2148
VOUT1
To Load
VIN2 VIN2 ON
Any Active HI VOUT2 Load Switch
FLAGB GND
To Load
Power good function in sequential startup. No battery is loaded to the output
Power Good
FPF2148 has a "Power Good" feature. PGOOD pin is an open-drain MOSFET which asserts high when the output voltage reaches 90% of the input voltage. PGOOD pin requires an external pull up resistor that is connected to the output voltage when there is no battery in the load side and the logic level of the subsequent controller permits. This would give logic levels similar to a CMOS output stage for PGOOD, while still keeping the option to tie the pull-up to a different supply voltage. A 100K is recommended to be used as pull up resistor. The PGOOD pin status is independent of the ONB pin position. This mean that PGOOD pin stays low when the load switch is OFF. If the Power Good feature is not used in the application the pin can be connected directly to GND.
Sequential Startup using Power Good
The power of FPF2148 PGOOD pin can be connected to another active HI load switch's enable pin to implement sequential startup. PGOOD pin asserts low when the load switch is OFF. This feature allows driving a subsequent circuit. The above diagram illustrates power good function in sequential startup. As the VOUT1 of the first load switch starts to ramp to the 90% of its input voltage the second switch remains in OFF state since the ON pin of the second switch stays low. Whereas the VOUT1 passes the 90% threshold, power good signal becomes active and asserts high. This signal will turn on the second load switch and VOUT2 will start to increase. The total startup time may vary according to the difference between supply voltages that are used in the application.
FPF2148 Rev. B3
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FPF2148 Full Function Load Switch
Dimensional Outline and Pad Layout
FPF2148 Rev. B3
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TRADEMARKS
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FPF2148 Full Function Load Switch
DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION, OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. THESE SPECIFICATIONS DO NOT EXPAND THE TERMS OF FAIRCHILD'S WORLDWIDE TERMS AND CONDITIONS, SPECIFICALLY THE WARRANTY THEREIN, WHICH COVERS THESE PRODUCTS. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
PRODUCT STATUS DEFINITIONS Definition of Terms Datasheet Identification Advance Information Product Status Formative or In Design Definition This datasheet contains the design specifications for product development. Specifications may change in any manner without notice. This datasheet contains preliminary data; supplementary data will be published at a later date. Fairchild Semiconductor reserves the right to make changes at any time without notice to improve design. This datasheet contains final specifications. Fairchild Semiconductor reserves the right to make changes at any time without notice to improve design. This datasheet contains specifications on a product that has been discontinued by Fairchild semiconductor. The datasheet is printed for reference information only.
Rev. I30
Preliminary
First Production
No Identification Needed
Full Production
Obsolete
Not In Production
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