Datasheet TPS2550, TPS2551 Datasheet (Texas Instruments)

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* USB Requirement that downstream-facing ports

are bypassed with at least 120 F per hubm

FAULT

OUT

ILIM

GND

PowerPad

USBData

USB Port

120 F*m

R 15k

ILIM

0.1 Fm

100k

FAULT

INPUT

5VUSB

FAULT Signal

ControlSignal

TPS2550/51

OUT

GND

ILIM FAULT

TPS2550/TPS2551

DBVPACKAGE

(TOP VIEW)

TPS2550/TPS2551

DRVPACKAGE

(TOP VIEW)

OUT

GND

ILIM

FAULT

PAD

EN= ActiveLowfortheTPS2550 EN= ActiveHighfortheTPS2551

TPS2014600mA TPS20151 A TPS2041B500mA TPS2051B500mA TPS2045A 250mA TPS2049100mA TPS2055A 250mA TPS20611 A TPS20651 A TPS20681.5 A TPS20691.5 A

TPS2042B500mA TPS2052B500mA TPS2046B250mA TPS2056250mA TPS20621 A TPS20661 A TPS20601.5 A TPS20641.5 A

TPS2080500mA TPS2081500mA TPS2082500mA TPS2090250mA TPS2091250mA TPS2092250mA

TPS2043B500mA TPS2053B500mA TPS2047B250mA TPS2057A 250mA TPS20631 A TPS20671 A

TPS2044B500mA TPS2054B500mA TPS2048A 250mA TPS2058250mA

TPS2085500mA TPS2086500mA TPS2087500mA TPS2095250mA TPS2096250mA TPS2097250mA

TPS201xA 0.2A to2 A TPS202x0.2 A to2A TPS203x0.2 A to2A

GENERAL SWITCHCATALOG

33m ,SingleW 80m ,SingleW

80m ,DualW 80m ,DualW

80m , TripleW

80m ,QuadW 80m ,QuadW

TPS2550 TPS2551

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SLVS736 – FEBRUARY 2008

ADJUSTABLE CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES

FEATURES

• Adjustable Current-Limit, 100 mA – 1100 mA

• Fast Overcurrent Response - 2 µ S Typical

• 85-m Ω High-Side MOSFET (DBV Package)

• Reverse Input-Output Voltage Protection

• Operating Range: 2.5 V to 6.5 V

• Deglitched Fault Report

• 1- µ A Maximum Standby Supply Current

• Ambient Temperature Range: – 40 ° C to 85 ° C

• Built-in Soft-Start

• 15 kV ESD Protection (with external

capacitance) output load exceeds the current-limit threshold or a

APPLICATIONS

• USB Ports/Hubs

• Cell phones

• Laptops

• Heavy Capacitive Loads

• Reverse-Voltage Protection

DESCRIPTION

The TPS2550/51 power-distribution switch is intended for applications where heavy capacitive loads and short-circuits are likely to be encountered, incorporating a 100-m Ω , N-channel MOSFET in a single package. The current-limit threshold is user adjustable between 100 mA and 1.1 A via an external resistor. The power-switch rise and fall times are controlled to minimize current surges during switching.

The device limits the output current to a desired level by switching into a constant-current mode when the

short is present. An internal reverse-voltage detection comparator disables the power-switch in the event that the output voltage is driven higher than the input to protect devices on the input side of the switch. The FAULT logic output asserts low during both overcurrent and reverse-voltage conditions.

PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

Figure 1. Typical Application as USB Power Switch

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

This device contains circuits to protect its inputs and outputs against damage due to high static voltages or electrostatic fields. These circuits have been qualified to protect this device against electrostatic discharges (ESD) of up to 2 kV according to MIL-STD-883C, Method 3015; however, it is advised that precautions be taken to avoid application of any voltage higher than maximum-rated voltages to these high-impedance circuits. During storage or handling the device leads should be shorted together or the device should be placed in conductive foam. In a circuit, unused inputs should always be connected to an appropriate logic voltage level, preferably either VCC or ground. Specific guidelines for handling devices of this type are contained in the publication Guidelines for Handling Electrostatic-Discharge-Sensitive (ESDS) Devices and Assemblies available from Texas Instruments.

AVAILABLE OPTIONS AND ORDERING INFORMATION

DEVICE AMBIENT ENABLE SON

(1)

TEMPERATURE (DRV) (DBV) CONTINUOUS LOAD CURRENT

TPS2550 Active low TPS2550DRV TPS2550DBV 1.1 A TPS2551 Active high TPS2551DRV TPS2551DBV 1.1 A

– 40 ° C to 85 ° C

(1) Add an R suffix to the device type for tape and reel.

(1)

SOT23

RECOMMENDED MAXIMUM

ABSOLUTE MAXIMUM RATINGS

over operating free-air temperature range unless otherwise noted

Voltage range on IN, OUT, EN or EN, ILIM, FAULT – 0.3 to 7 V Voltage range from IN to OUT – 7 to 7 V

Continuous output current Internally limited

OUT

Continuous total power dissipation FAULT sink current 25 mA

ILIM source current 1 mA

ESD

Maximum junction temperature – 40 to 150 ° C

Storage temperature – 65 to 150 ° C

Sgt

Lead temperature 1,6 mm (1/16-inch) from case for 10 seconds 300 ° C

(1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings

only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) Voltages are referenced to GND unless otherwise noted.

HBM 2 kV CDM 500 V

(1) (2)

VALUE UNIT

See "Dissipation Rating

Table"

DISSIPATION RATING TABLE

BOARD PACKAGE THERMAL THERMAL TA≤ 25 ° C DERATING TA= 70 ° C TA= 85 ° C

(1)

Low-K High-K Low-K High-K

DBV 350 ° C/W 55 ° C/W 285 mW 2.85 mW/ ° C 155 mW 114 mW

(2)

DBV 160 ° C/W 55 ° C/W 625 mW 6.25 mW/ ° C 340 mW 250 mW

(1)

DRV 140 ° C/W 20 ° C/W 715 mW 7.1 mW/ ° C 395 mW 285 mW

(2)

DRV 75 ° C/W 20 ° C/W 1330 mW 13.3 mW/ ° C 730 mW 530 mW

(1) The JEDEC low-K (1s) board used to derive this data was a 3in × 3in, two-layer board with 2-ounce copper traces on top of the board. (2) The JEDEC high-K (2s2p) board used to derive this data was a 3in × 3in, multilayer board with 1-ounce internal power and ground

planes and 2-ounce copper traces on top and bottom of the board.

RESISTANCE RESISTANCE

RATING

TA= 25 ° C RATING RATING

POWER FACTOR ABOVE POWER POWER

Product Folder Link(s): TPS2550 TPS2551

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RECOMMENDED OPERATING CONDITIONS

MIN MAX UNIT

/EN

OUT

ILIM

/FAULT

Input voltage, IN 2.5 6.5 V

Enable voltage V

TPS2550 0 6.5

TPS2551 0 6.5 Continuous output current, OUT 0 1.1 A Current-limit set resistor from ILIM to GND 14.3 80.6 k Ω FAULT sink current 0 10 mA

Operating virtual junction temperature

DRV – 40 105

DBV – 40 125

ELECTRICAL CHARACTERISTICS

over recommended operating junction temperature range, 2.5 V ≤ V (unless otherwise noted)

PARAMETER TEST CONDITIONS

POWER SWITCH

DBV package, TJ= 25 ° C 85 95

DS(on)

Static drain-source on-state resistance m Ω

Rise time, output

Fall time, output

ENABLE INPUT EN OR EN

V V I

off

High-level input voltage 1.1

Low-level input voltage 0.66

Input current VEN= 0 V or 6.5 V, V Turnon time 3 ms Turnoff time 3 ms

CURRENT LIMIT

IOS

Short-circuit current, OUT connected to GND R

Current-limit threshold (Maximum DC output current I

Response time to short circuit VIN= 5.0 V (see Figure 3 ) 2 µ s

REVERSE-VOLTAGE PROTECTION

Reverse-voltage comparator trip point (V

– VIN)

OUT

Time from reverse-voltage condition to MOSFET turn off

SUPPLY CURRENT

IN_off

IN_on

REV

Supply current, low-level output 0.1 1 µ A

Supply current, high-level output

Reverse leakage current V

(1) Pulse-testing techniques maintain junction temperature close to ambient temperature; thermal effects must be taken into account

separately.

DBV package, – 40 ° C ≤ TJ≤ 125 ° C 135

DRV package, TJ= 25 ° C 100 115

DRV package, – 40 ° C ≤ TJ≤ 105 ° C 145

VIN= 6.5 V 1.0 1.5

VIN= 2.5 V 0.65 1.0

VIN= 6.5 V 0.2 0.5

VIN= 2.5 V 0.2 0.5

/EN

CL= 1 µ F, RL= 100 Ω , (see Figure 2 )

delivered to load) R

OUT

VIN= 5.0 V 3 5 7 ms

VIN= 6.5 V, No load on OUT, VEN= 6.5 V or VEN= 0 V, 14.3 k Ω

≤ R

≤ 80.6 k Ω

ILIM

VIN= 6.5 V, No load on OUT, VEN= 0 V or

VEN= 6.5 V

= 6.5 V, VIN= 0 V TJ= 25 ° C 0.01 1 µ A

OUT

≤ 6.5 V, R

ILIM

(1)

= 14.3 k Ω , V

= 0 V, or V

/EN

MIN TYP MAX UNIT

CL= 1 µ F, RL= 100 Ω , (see Figure 2 )

= 0 V or 6.5 V – 0.5 0.5 µ A

= 80.6 k Ω 110 215 300

ILIM

= 38.3 k Ω 300 500 650

ILIM

= 15 k Ω 1050 1400 1650

ILIM

= 80.6 k Ω 290 315 340

ILIM

= 38.3 k Ω 620 665 705

ILIM

= 15 k Ω 1550 1650 1750

ILIM

95 135 190 mV

= 15 k Ω 150 µ A

ILIM

= 80.6 k Ω 130 µ A

ILIM

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

= 5.0 V

° C

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

ELECTRICAL CHARACTERISTICS (continued)

over recommended operating junction temperature range, 2.5 V ≤ V (unless otherwise noted)

PARAMETER TEST CONDITIONS

UNDERVOLTAGE LOCKOUT

FAULT FLAG

THERMAL SHUTDOWN

Low-level input voltage, IN VINrising 2.35 2.45 V

UVLO

Hysteresis, IN TJ= 25 ° C 25 mV

Output low voltage, FAULT I

Off-state leakage V

FAULT deglitch

Thermal shutdown threshold 155 ° C Thermal shutdown threshold in current-limit 135 ° C Hysteresis 15 ° C

= 1 mA 180 mV

/FAULT

= 6.5 V 1 µ A

/FAULT

FAULT assertion or de-assertion due to overcurrent condition 5 7.5 10 ms

FAULT assertion or de-assertion due to reverse-voltage

condition

≤ 6.5 V, R

ILIM

(1)

= 14.3 k Ω , V

= 0 V, or V

/EN

MIN TYP MAX UNIT

2 4 6 ms

= 5.0 V

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Charge

Pump

Driver

UVLO

Current

Limit

Thermal

Sense

GND

ILIM

OUT

FAULT

Reverse

Voltage

Comparator

Current

Sense

4-ms

Deglitch

8-msDeglitch

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

DEVICE INFORMATION

Terminal Functions

TERMINAL

NAME TPS2550DBV TPS2551DBV TPS2550DRV TPS2551DRV

EN 3 – 4 – I Enable input, logic low turns on power switch EN – 3 – 4 I Enable input, logic high turns on power switch GND 2 2 5 5 Ground connection; should be connected

IN 1 1 6 6 I Input voltage; connect a 0.1 µ F or greater

FAULT 4 4 3 3 O Active-low open-drain output, asserted during

OUT 6 6 1 1 O Power-switch output ILIM 5 5 2 2 I External resistor used to set current-limit

POWER – – PAD PAD Internally connected to GND; used to heat-sink PAD the part to the circuit board traces. Should be

I/O DESCRIPTION

externally to POWER PAD

ceramic capacitor from IN to GND as close to the IC as possible.

overcurrent, overtemperature, or reverse-voltage conditions.

threshold; recommended 14.3 k Ω ≤ R k Ω .

connected to GND pin.

ILIM

≤ 80.6

FUNCTIONAL BLOCK DIAGRAM

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OUT

90%

10%

50%

90%

10%

OUT

VOLTAGEWAVEFORMS

TESTCIRCUIT

off

50%

90%

10%

off

OUT

IOS

OUT

DECREASING

LOAD

RESISTANCE

OUT

DECREASING

LOAD

RESISTANCE

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

PARAMETER MEASUREMENT INFORMATION

Figure 2. Test Circuit and Voltage Waveforms

Figure 3. Response Time to Short-Circuit Waveform

Figure 4. Output Voltage vs. Current-Limit Threshold

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

TYPICAL CHARACTERISTICS

Figure 5. Turnon Delay and Rise Time

Figure 6. Turnoff Delay and Fall Time

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

TYPICAL CHARACTERISTICS (continued)

Figure 7. Device Enabled into Short-Circuit

Figure 8. Full-Load to Short-Circuit Transient Response

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TYPICAL CHARACTERISTICS (continued)

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

Figure 9. Short-Circuit to Full-Load Recovery Response

Figure 10. No-Load to Short-Circuit Transient Response

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

TYPICAL CHARACTERISTICS (continued)

Figure 11. Short-Circuit to No-Load Recovery Response

Figure 12. No Load to 1 Ω Transient Response

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TYPICAL CHARACTERISTICS (continued)

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

Figure 13. 1 Ω to No Load Transient Response

Figure 14. Reverse-Voltage Protection Response

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2.30

UVLOFalling

T -JunctionTemperature-°C

-50 0 50 100 150

2.40

2.31

2.32

2.33

2.34

2.35

2.36

2.37

2.38

2.39

UVLORising

UVLO-UndervoltageLockout-V

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

TYPICAL CHARACTERISTICS (continued)

Figure 15. Reverse-Voltage Protection Recovery

Figure 16. UVLO – Undervoltage Lockout – V

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T -JunctionTemperature-°C

-50 0 50 100 150

0.50

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

IIN-SupplyCurrent,OutputDisabled- Am

V =6.5V

V =5V

V =3.3V

V =2.5V

T -JunctionTemperature-°C

-50 0 50 100 150

150

105

120

135

IIN-SupplyCurrent,OutputEnabled- Am

V =5V

V =3.3V

V =2.5V

V =6.5V

R =20k

ILIM

TYPICAL CHARACTERISTICS (continued)

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

Figure 17. IIN– Supply Current, Output Disabled – µ A

Figure 18. IIN– Supply Current, Output Enabled – µ A

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PeakCurrent- A

0 1.5 3 4.5 6

CurrentLimitResponse- sm

V =5V, T =25°C

T -JunctionTemperature-°C

-50 0 50 100 150

100

125

150

r -StaticDrain-SourceOn-StateResistance-m

DS(on)

DRVPackage

DBVPackage

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

TYPICAL CHARACTERISTICS (continued)

Figure 20. MOSFET r

Figure 19. Current Limit Response – µ s

Vs. Junction Temperature

DS(on)

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

DETAILED DESCRIPTION

OVERVIEW

The TPS2550/51 are current-limited, power distribution switches using N-channel MOSFETs for applications where short-circuits or heavy capacitive loads will be encountered. These devices allow the user to program the current-limit threshold between 100 mA and 1.1 A via an external resistor. Additional device shutdown features include overtemperature protection and reverse-voltage protection. The device incorporates an internal charge pump and gate drive circuitry necessary to drive the N-channel MOSFET. The charge pump supplies power to the driver circuit and provides the necessary voltage to pull the gate of the MOSFET above the source. The charge pump operates from input voltages as low as 2.5 V and requires little supply current. The driver controls the gate voltage of the power switch. The driver incorporates circuitry that controls the rise and fall times of the output voltage to limit large current and voltage surges and provide built-in soft-start functionality.

OVERCURRENT

The TPS2550/51 responds to an overcurrent condition by limiting its output current to the I shown in Figure 21 . Three response profiles are possible depending on the loading conditions and are summarized in Figure 4 .

One response profile occurs if the TPS2550/51 is enabled into a short-circuit. The output voltage is held near zero potential with respect to ground and the TPS2550/51 ramps the output current to IOS(see Figure 7 ).

A second response profile occurs if a short is applied to the output after the TPS2550/51 is enabled. The device responds to the overcurrent condition within time t

(see Figure 3 ). The current-sense amplifier is over-driven

IOS

during this time and momentarily disables the internal current-limit MOSFET. The current-sense amplifier gradually recovers and limits the output current to IOS.

A third response profile occurs if the load current gradually increases. The device first limits the load current to IOC. If the load demands a current greater than IOC, the TPS2550/51 folds back the current to IOSand the output voltage decreases to IOSx R

for a resistive load, which is shown in Figure 4 .

LOAD

The TPS2550/51 thermal cycles if an overload condition is present long enough to activate thermal limiting in any of the above cases. The device turns off when the junction temperature exceeds 135 ° C (typ). The device remains off until the junction temperature cools 15 ° C (typ) and then restarts. The TPS2550/51 cycles on/off until the overload is removed (see Figure 9 and Figure 11 ) .

and I

levels

REVERSE-VOLTAGE PROTECTION

The reverse-voltage protection feature turns off the N-channel MOSFET whenever the output voltage exceeds the input voltage by 135 mV (typical) for 4-ms. This prevents damage to devices on the input side of the TPS2550/51 by preventing significant current from sinking into the input capacitance. The N-channel MOSFET is allowed to turn-on once the output voltage goes below the input voltage for the same 4-ms deglitch time. The reverse-voltage comparator also asserts the FAULT output (active-low) after 4-ms.

FAULT RESPONSE

The FAULT open-drain output is asserted (active low) during an overcurrent, overtemperature or reverse-voltage condition. The output remains asserted until the fault condition is removed. The TPS2550/51 is designed to eliminate false FAULT reporting by using an internal delay "deglitch" circuit for overcurrent (7.5-ms) and reverse-voltage (4-ms) conditions without the need for external circuitry. This ensures that FAULT is not accidentally asserted due to normal operation such as starting into a heavy capacitive load. The deglitch circuitry delays entering and leaving fault conditions. Overtemperature conditions are not deglitched and assert the FAULT signal immediately.

UNDERVOLTAGE LOCKOUT (UVLO)

The undervoltage lockout (UVLO) circuit disables the power switch until the input voltage reaches the UVLO turn-on threshold. Built-in hysteresis prevents unwanted on/off cycling due to input voltage drop from large current surges.

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

ENABLE ( EN OR EN)

The logic enable controls the power switch, bias for the charge pump, driver, and other circuits to reduce the supply current. The supply current is reduced to less than 1- µ A when a logic high is present on EN or when a logic low is present on EN. A logic low input on EN or a logic high input on EN enables the driver, control circuits, and power switch. The enable input is compatible with both TTL and CMOS logic levels.

THERMAL SENSE

The TPS2550/51 protects itself with two independent thermal sensing circuits that monitor the operating temperature of the power-switch and disables operation if the temperature exceeds recommended operating conditions. The device operates in constant-current mode during an overcurrent conditions, which increases the voltage drop across power-switch. The power dissipation in the package is proportional to the voltage drop across the power-switch, so the junction temperature rises during an overcurrent condition. The first thermal sensor turns off the power-switch when the die temperature exceeds 135 ° C and the part is in current limit. The second thermal sensor turns off the power-switch when the die temperature exceeds 155 ° C regardless of whether the power-switch is in current limit. Hysteresis is built into both thermal sensors, and the switch turns on after the device has cooled approximately 15 ° C. The switch continues to cycle off and on until the fault is removed. The open-drain false reporting output FAULT is asserted (active low) immediately during an overtemperature shutdown condition.

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

APPLICATION INFORMATION

INPUT AND OUTPUT CAPACITANCE

Input and output capacitance improve the performance of the device; the actual capacitance should be optimized for the particular application. For all applications, a 0.01 µ F to 0.1 µ F ceramic bypass capacitor between IN and GND is recommended as close to the device as possible for local noise de-coupling. This precaution reduces ringing on the input due to power-supply transients. Additional input capacitance may be needed on the input to reduce voltage overshoot from exceeding the absolute maximum voltage of the device during heavy transients. This is especially important during bench testing when long, inductive cables are used to connect the evaluation board to the bench power-supply.

Placing a high-value electrolytic capacitor on the output pin is recommended when the large transient currents are expected on the output. Additionally, bypassing the output with a 0.01 µ F to 0.1 µ F ceramic capacitor improves the immunity of the device to short-circuit transients.

PROGRAMMING THE CURRENT-LIMIT THRESHOLD

The overcurrent threshold is user programmable via an external resistor. Many applications require that the minimum current-limit is above a certain current level or that the maximum current-limit is below a certain current level, so it is important to consider the tolerance of the overcurrent threshold when selecting a value for R The following equations and Figure 21 can be used to calculate the resulting overcurrent threshold for a given external resistor value (R and process. The traces routing the R parasitic effects on the current-limit accuracy.

There are two important current-limit thresholds for the device and are related by Figure 4 . The first threshold is the short-circuit current threshold IOS. I short-circuit or a short-circuit is applied during normal operation. The second threshold is the overcurrent threshold IOC. I current. I

consider both I

is the peak DC current that can be delivered to the load before the device begins to limit

is important if ramped loads or slow transients are common to the application. It is important to

and I

occurs 1) above a minimum load current or 2) below a maximum load current. To design above a minimum current-limit threshold, find the intersection of R

current on the I

OS(min)

minimum threshold is important to ensure start-up into full-load or heavy capacative loads. The resulting maximum DC load current is the intersection of the selected value of R

To design below a maximum DC current level, find the intersection of R current on the I

OC(max)

maximum threshold is important to avoid current-limiting upstream power supplies causing the input voltage bus to droop. The resulting minimum short-circuit current is the intersection of the selected value of R I

curve.

OS(min)

). Figure 21 includes current-limit tolerance due to variations caused by temperature

ILIM

when choosing R

curve and choose a value of R

resistor to the TPS2550/51should be as short as possible to reduce

ILIM

is the current delivered to the load if the part is enabled into a

. R

ILIM

can be selected to provide a current-limit threshold that

ILIM

below this value. Programming the current-limit above a

ILIM

above this value. Programming the current-limit below a

ILIM

and the maximum desired load

ILIM

and the I

ILIM

OC(max)

and the maximum desired load

curve.

and the

ILIM

Overcurrent Threshold Equations (I

• I

OC(max) OC(typ) OC(min)

(mA) = (24500 V) / (R

(mA) = (23800 V) / (R

(mA) = (23100 V) / (R

Short-Circuit Current Equations (I

• I

OS(max)

• I

OS(typ)

• I

OS(min)

where 14.3 k Ω ≤ R

(mA) = (25500 V) / (R

(mA) = (28700 V) / (R

(mA) = (39700 V) / (R

≤ 80.6 k Ω . I

ILIM

OS(typ)

0.975

k Ω )

0.985

k Ω )

0.996

k Ω )

1.013

k Ω )

1.114

k Ω )

1.342

k Ω )

and I

Product Folder Link(s): TPS2550 TPS2551

OS(max)

are not plotted to improve graph clarity.

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100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

15 20 25 30 35 40 45 50 55 60 65 70 75 80

R -k

ILIM

Current-LimitThreshold-mA

OC(max)

OC(typ)

OC(min)

OS(min)

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

Figure 21. Current-Limit Threshold Vs.R

APPLICATION 1: DESIGNING ABOVE A MINIMUM CURRENT-LIMIT

Some applications require that current-limiting cannot occur below a certain threshold. For this example, assume that 1 A must be delivered to the load so that the minimum desired current-limit threshold is 1000 mA. Use the IOSequations and Figure 21 to select R

• I

• R

(mA) = 1000 mA

OS(min)

(mA) = (39700 V) / (R

OS(min)

(k Ω ) = [(39700 V) / (I

ILIM

= 15.54 k Ω

ILIM

OS(min)

Select the closest 1% resistor less than the calculated value: R threshold at 1 A . Use the IOCequations, Figure 21 , and the previously calculated value for R maximum resulting current-limit threshold.

• R

• I

The resulting maximum current-limit theshold is 1.7 A with a 15.4 k Ω resistor.

APPLICATION 2: DESIGNING BELOW A MAXIMUM CURRENT-LIMIT

Some applications require that current-limiting must occur below a certain threshold. For this example, assume that the desired upper current-limit threshold must be below 1.25 A to protect an up-stream power supply. Use the IOCequations and Figure 21 to select R

• I

• R

= 15.4 k Ω

ILIM OC(max) OC(max) OC(max)

OC(max) OC(max)

(mA) = (24500 V) / (R (mA) = (24500 V) / (15 (k Ω )) = 1703 mA

(mA) = 1250 mA (mA) = (24500 V) / (R

(k Ω ) = [(24500 V) / (I

ILIM

= 21.15 k Ω

ILIM

OC(max)

ILIM

1.342

(k Ω ))

(mA))]

1/1.342

0.975

(k Ω ))

0.975

ILIM

0.975

(k Ω )) (mA))]

1/0.975

Product Folder Link(s): TPS2550 TPS2551

ILIM

= 15.4 k Ω . This sets the minimum current-limit

ILIM

to calculate the

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

Select the closest 1% resistor greater than the calculated value: R

= 21.5 k Ω . This sets the maximum

ILIM

current-limit threshold at 1.25 A . Use the IOSequations, Figure 21 , and the previously calculated value for R to calculate the minimum resulting current-limit threshold.

• R

• I

= 21.5 k Ω

ILIM

(mA) = (39700 V) / (R

OS(min)

(mA) = (39700 V) / (21.5 (k Ω ))

OS(min)

= 647 mA

OS(min)

ILIM

1.342

(k Ω ))

The resulting minimum current-limit threshold is 647 mA with a 21.5 k Ω resistor.

POWER DISSIPATION AND JUNCTION TEMPERATURE

The low on-resistance of the N-channel MOSFET allows small surface-mount packages to pass large currents. It is good design practice to estimate power dissipation and junction temperature. The below analysis gives an approximation for calculating junction temperature based on the power dissipation in the package. However, it is important to note that thermal analysis is strongly dependent on additional system level factors. Such factors include air flow, board layout, copper thickness and surface area, and proximity to other devices dissipating power. Good thermal design practice must include all system level factors in addition to individual component analysis.

Begin by determining the r temperature. As an initial estimate, use the highest operating ambient temperature of interest and read r from the typical characteristics graph. Using this value, the power dissipation can be calculated by:

= r

DS(on)

× I

OUT

Where:

= Total power dissipation (W)

= Power switch on-resistance ( Ω )

DS(on)

= Maximum current-limit threshold (A)

OUT

This step calculates the total power dissipation of the N-channel MOSFET. Finally, calculate the junction temperature:

TJ= P

× R

+ T

Θ JA

Where:

TA= Ambient temperature ( ° C) R

= Thermal resistance ( ° C/W)

Θ JA

= Total power dissipation (W)

Compare the calculated junction temperature with the initial estimate. If they are not within a few degrees, repeat the calculation using the "refined" r iterations are generally sufficient to achieve the desired result. The final junction temperature is highly dependent on thermal resistance R

, and thermal resistance is highly dependent on the individual package and board

θ JA

layout. The "Dissipating Rating Table" at the begginng of this document provides example thermal resistances for specific packages and board layouts.

of the N-channel MOSFET relative to the input voltage and operating

DS(on)

from the previous calculation as the new estimate. Two or three

DS(on)

ILIM

UNIVERSAL SERIAL BUS (USB) POWER-DISTRIBUTION REQUIREMENTS

One application for this device is for current-limiting in universal serial bus (USB) applications. The original USB interface was a 12-Mb/s or 1.5-Mb/s, multiplexed serial bus designed for low-to-medium bandwidth PC peripherals (e.g., keyboards, printers, scanners, and mice). As the demand for more bandwidth increased, the USB 2.0 standard was introduced increasing the maximum data rate to 480-Mb/s. The four-wire USB interface is conceived for dynamic attach-detach (hot plug-unplug) of peripherals. Two lines are provided for differential data, and two lines are provided for 5-V power distribution.

USB data is a 3.3-V level signal, but power is distributed at 5 V to allow for voltage drops in cases where power is distributed through more than one hub across long cables. Each function must provide its own regulated 3.3 V from the 5-V input or its own internal power supply. The USB specification classifies two different classes of

Product Folder Link(s): TPS2550 TPS2551

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TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

devices depending on its maximum current draw. A device classified as low-power can draw up to 100 mA as defined by the standard. A device classified as high-power can draw up to 500 mA. It is important that the minimum current-limit threshold of the current-limiting power-switch exceed the maximum current-limit draw of the intended application. The latest USB standard should always be referenced when considering the current-limit threshold

The USB specification defines two types of devices as hubs and functions. A USB hub is a device that contains multiple ports for different USB devices to connect and can be self-powered (SPH) or bus-powered (BPH). A function is a USB device that is able to transmit or receive data or control information over the bus. A USB function can be embedded in a USB hub. A USB function can be one of three types included in the list below.

• Low-power, bus-powered function

• High-power, bus-powered function

• Self-powered function

SPHs and BPHs distribute data and power to downstream functions. The TPS2550/51 has higher current capability than required for a single USB port allowing it to power multiple downstream ports.

SELF-POWERED AND BUS-POWERED HUBS

A SPH has a local power supply that powers embedded functions and downstream ports. This power supply must provide between 4.75 V to 5.25 V to downstream facing devices under full-load and no-load conditions. SPHs are required to have current-limit protection and must report overcurrent conditions to the USB controller. Typical SPHs are desktop PCs, monitors, printers, and stand-alone hubs.

A BPH obtains all power from an upstream port and often contains an embedded function. It must power up with less than 100 mA. The BPH usually has one embedded function, and power is always available to the controller of the hub. If the embedded function and hub require more than 100 mA on power up, the power to the embedded function may need to be kept off until enumeration is completed. This is accomplished by removing power or by shutting off the clock to the embedded function. Power switching the embedded function is not necessary if the aggregate power draw for the function and controller is less than 100 mA. The total current drawn by the bus-powered device is the sum of the current to the controller, the embedded function, and the downstream ports, and it is limited to 500 mA from an upstream port.

LOW-POWER BUS-POWERED AND HIGH-POWER BUS-POWERED FUNCTIONS

Both low-power and high-power bus-powered functions obtain all power from upstream ports. Low-power functions always draw less than 100 mA; high-power functions must draw less than 100 mA at power up and can draw up to 500 mA after enumeration. If the load of the function is more than the parallel combination of 44 Ω and 10 µ F at power up, the device must implement inrush current limiting.

USB POWER-DISTRIBUTION REQUIREMENTS

USB can be implemented in several ways regardless of the type of USB device being developed. Several power-distribution features must be implemented.

• SPHs must: – Current-limit downstream ports – Report overcurrent conditions

• BPHs must: – Enable/disable power to downstream ports – Power up at <100 mA – Limit inrush current (<44 Ω and 10 µ F)

• Functions must: – Limit inrush currents – Power up at <100 mA

The feature set of the TPS2550/51 meets each of these requirements. The integrated current-limiting and overcurrent reporting is required by self-powered hubs. The logic-level enable and controlled rise times meet the need of both input and output ports on bus-powered hubs and the input ports for bus-powered functions.

Product Folder Link(s): TPS2550 TPS2551

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OUT

GND

FAULT

ILIM

Input

TPS2551

PowerPad

Output

0.1 Fm

100k

FAULT

0.1 F

RETRY

20k

ILIM

LOAD

1kW

OUT

GND

FAULT

ILIM

ExternalLogic

Signal&Driver

TPS2551

PowerPad

Input

0.1 Fm

100k

FAULT

0.1 F

RETRY

20k

ILIM

LOAD

1kW

Output

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

AUTO-RETRY FUNCTIONALITY

Some applications require that an overcurrent condition disables the part momentarily during a fault condition and re-enables after a pre-set time. This auto-retry functionality can be implemented with an external resistor and capacitor. During a fault condition, FAULT pulls low disabling the part. The part is disabled when EN is pulled low, and FAULT goes high impedance allowing C on EN reaches the turnon threshold, and the auto-retry time is determined by the resistor/capacitor time constant. The part will continue to cycle in this manner until the fault condition is removed.

Figure 22. Auto-Retry Functionality

to begin charging. The part re-enables when the voltage

RETRY

Some applications require auto-retry functionality and the ability to enable/disable with an external logic signal. The figure below shows how an external logic signal can drive EN through R

and maintain auto-retry

FAULT

functionality. The resistor/capacitor time constant determines the auto-retry time-out period.

Figure 23. Auto-Retry Functionality With External EN Signal

LATCH-OFF FUNCTIONALITY

The circuit in Figure 24 uses an SN74HC00 quad-NAND gate to implement overcurrent latch-off. The SN74HC00 high-speed CMOS logic gate is selected because it operates over the 2.5V – 6.5V range of the TPS2550/51.

This circuit is designed to work with the active-high TPS2551. ENABLE must be logic low during start-up until V is stable to ensure that the switch initializes in the OFF state. A logic high on ENABLE turns on the switch after V

is stable. FAULT momentarily pulls low during an overcurrent condition, which latches STAT logic low and

disables the switch. The host can monitor STAT for an overcurrent condition. Toggling ENABLE resets STAT and re-enables the switch.

Product Folder Link(s): TPS2550 TPS2551

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OUT

GND

FAULT

ILIM

Input

TPS2551

PowerPad

Output

10kW

STAT

ExternalLogic

EnableSignal

SN74HC00D

0.1 Fm

10k

FAULT

15kW

LOAD

OUT

GND

FAULT

ILIM

ControlSignal

Input

TPS2550/51

FAULT Signal

PowerPad

Output

CurrentLimit

ControlSignal

0.1 Fm

100k

FAULT

80.6kW R2

20kW

LOAD

2N7002

TPS2550 TPS2551

SLVS736 – FEBRUARY 2008

Figure 24. Overcurrent Latch-Off Using a Quad-NAND Gate

TWO-LEVEL CURRENT-LIMIT CIRCUIT

Some applications require different current-limit thresholds depending on external system conditions. Figure 25 shows an implementation for an externally controlled, two-level current-limit circuit. The current-limit threshold is set by the total resistance from ILIM to GND (see previously discussed "Programming the Current-Limit Threshold" section). A logic-level input enables/disables MOSFET Q1 and changes the current-limit threshold by modifying the total resistance from ILIM to GND. Additional MOSFETs/resistor combinations can be used in parallel to Q1/R2 to increase the number of additional current-limit levels.

NOTE:

ILIM should never be driven directly with an external signal.

Figure 25. Two-Level Current-Limit Circuit

Product Folder Link(s): TPS2550 TPS2551

PACKAGE OPTION ADDENDUM

www.ti.com

7-Apr-2008

PACKAGING INFORMATION

Orderable Device Status

(1)

Package

Type

Package Drawing

Pins Package

Qty

Eco Plan

TPS2550DBVR ACTIVE SOT-23 DBV 6 3000 Green (RoHS &

no Sb/Br)

TPS2550DBVRG4 ACTIVE SOT-23 DBV 6 3000 Green (RoHS &

no Sb/Br)

TPS2550DBVT ACTIVE SOT-23 DBV 6 250 Green (RoHS &

no Sb/Br)

TPS2550DBVTG4 ACTIVE SOT-23 DBV 6 250 Green (RoHS &

no Sb/Br)

TPS2550DRVR ACTIVE SON DRV 6 3000 Green (RoHS &

no Sb/Br)

TPS2550DRVRG4 ACTIVE SON DRV 6 3000 Green (RoHS &

no Sb/Br)

TPS2550DRVT ACTIVE SON DRV 6 250 Green (RoHS &

no Sb/Br)

TPS2550DRVTG4 ACTIVE SON DRV 6 250 Green (RoHS &

no Sb/Br)

TPS2551DBVR ACTIVE SOT-23 DBV 6 3000 Green (RoHS &

no Sb/Br)

TPS2551DBVT ACTIVE SOT-23 DBV 6 250 Green (RoHS &

no Sb/Br)

TPS2551DRVR ACTIVE SON DRV 6 3000 Green (RoHS &

no Sb/Br)

TPS2551DRVRG4 ACTIVE SON DRV 6 3000 Green (RoHS &

no Sb/Br)

TPS2551DRVT ACTIVE SON DRV 6 250 Green (RoHS &

no Sb/Br)

TPS2551DRVTG4 ACTIVE SON DRV 6 250 Green (RoHS &

no Sb/Br)

(1)

The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in

a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device.

(2)

Lead/Ball Finish MSL Peak Temp

CU NIPDAU Level-1-260C-UNLIM

(3)

(2)

Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check

http://www.ti.com/productcontent for the latest availability information and additional product content details.

TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements

for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)

(3)

MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder

temperature.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is

Addendum-Page 1

PACKAGE OPTION ADDENDUM

www.ti.com

provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

7-Apr-2008

Addendum-Page 2

PACKAGE MATERIALS INFORMATION

www.ti.com

TAPE AND REEL INFORMATION

5-Apr-2008

*All dimensions are nominal

Device Package

TPS2550DBVR SOT-23 DBV 6 3000 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 TPS2550DBVT SOT-23 DBV 6 250 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 TPS2550DRVR SON DRV 6 3000 179.0 8.4 2.2 2.2 1.2 4.0 8.0 Q2 TPS2550DRVT SON DRV 6 250 179.0 8.4 2.2 2.2 1.2 4.0 8.0 Q2 TPS2551DBVR SOT-23 DBV 6 3000 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 TPS2551DBVT SOT-23 DBV 6 250 179.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 TPS2551DRVR SON DRV 6 3000 179.0 8.4 2.2 2.2 1.2 4.0 8.0 Q2 TPS2551DRVT SON DRV 6 250 179.0 8.4 2.2 2.2 1.2 4.0 8.0 Q2

Type

Package Drawing

Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

A0 (mm) B0 (mm) K0 (mm) P1

(mm)W(mm)

Pin1

Quadrant

Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION

www.ti.com

5-Apr-2008

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height(mm)

TPS2550DBVR SOT-23 DBV 6 3000 195.0 200.0 45.0 TPS2550DBVT SOT-23 DBV 6 250 195.0 200.0 45.0

TPS2550DRVR SON DRV 6 3000 195.0 200.0 45.0

TPS2550DRVT SON DRV 6 250 195.0 200.0 45.0 TPS2551DBVR SOT-23 DBV 6 3000 195.0 200.0 45.0 TPS2551DBVT SOT-23 DBV 6 250 195.0 200.0 45.0

TPS2551DRVR SON DRV 6 3000 195.0 200.0 45.0

TPS2551DRVT SON DRV 6 250 195.0 200.0 45.0

Pack Materials-Page 2

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TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed.

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Datasheet TPS2550, TPS2551 Datasheet (Texas Instruments)

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICATIONS

DESCRIPTION

ABSOLUTE MAXIMUM RATINGS

DISSIPATION RATING TABLE

RECOMMENDED OPERATING CONDITIONS

ELECTRICAL CHARACTERISTICS

DEVICE INFORMATION

PARAMETER MEASUREMENT INFORMATION

TYPICAL CHARACTERISTICS

DETAILED DESCRIPTION

OVERVIEW

OVERCURRENT

REVERSE-VOLTAGE PROTECTION

FAULT RESPONSE

UNDERVOLTAGE LOCKOUT (UVLO)

ENABLE ( EN OR EN)

THERMAL SENSE

APPLICATION INFORMATION

INPUT AND OUTPUT CAPACITANCE

PROGRAMMING THE CURRENT-LIMIT THRESHOLD

APPLICATION 1: DESIGNING ABOVE A MINIMUM CURRENT-LIMIT

APPLICATION 2: DESIGNING BELOW A MAXIMUM CURRENT-LIMIT

POWER DISSIPATION AND JUNCTION TEMPERATURE

UNIVERSAL SERIAL BUS (USB) POWER-DISTRIBUTION REQUIREMENTS

SELF-POWERED AND BUS-POWERED HUBS

LOW-POWER BUS-POWERED AND HIGH-POWER BUS-POWERED FUNCTIONS

USB POWER-DISTRIBUTION REQUIREMENTS

AUTO-RETRY FUNCTIONALITY

LATCH-OFF FUNCTIONALITY

TWO-LEVEL CURRENT-LIMIT CIRCUIT