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TPS25221
SLVSDT3D – JANUARY 2018 – REVISED DECEMBER 2019
TPS25221 2.5-V to 5.5-V, 2-A Continuous Current Limited Switch
1 Features
3 Description
•
•
•
•
•
•
•
•
•
•
•
The TPS25221 is intended for applications where
heavy capacitive loads and short circuits may be
encountered.
The
programmable
current-limit
threshold maybe set between 275 mA and 2.7 A
(typical) using an external resistor. ILIMIT accuracy as
tight as ±6% can be achieved at the higher currentlimit settings. Power-switch rise and fall times are
controlled to minimize current surges during turn on
and turn off.
1
2.5-V to 5.5-V VOPERATING
Pin-to-Pin with TPS2553
2-A ICONT_MAX
0.275-A to 2.7-A Adjustable ILIMIT (±6.5% at 1.7 A)
70-mΩ (typical) RON
1.5-µs Short Circuit Response
8-ms Fault Reporting Deglitch
Reverse Current Blocking (when disabled)
Built-In Soft Start
UL 60950 and UL 62368 Recognition
15-kV ESD Protection per IEC 61000-4-2 (with
external capacitance)
When a load attempts to draw current exceeding the
programmed ILIMIT the internal FET enters constant
current mode in order to keep ILOAD at or below ILIMIT.
The FAULT output will assert low during over-current
conditions after the built in de-glitch time.
Device Information(1)
2 Applications
•
•
•
•
PART NUMBER
USB Ports/Hubs, Laptops, Desktops
HDTV
Set Top Boxes
Optical Socket Protection
TPS25221
PACKAGE
BODY SIZE (NOM)
SOT-23 (6)
2.90 mm x 1.60 mm
WSON (6)
2.00 mm x 2.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
5-V USB
Input
USB Data
0.1 µF
IN
OUT
120 µF
RFAULT
20 NŸ
Fault Signal
Control Signal
USB
Port
ILIM
FAULT
RILIM USB requirement only*
20 NŸ
EN
GND
Thermal Pad
*USB requirement that downstream facing ports are bypassed with at
least 120 µF per hub.
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
TPS25221
SLVSDT3D – JANUARY 2018 – REVISED DECEMBER 2019
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
9
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
3
4
7.1
7.2
7.3
7.4
7.5
7.6
4
4
4
4
5
7
Absolute Maximum Ratings ......................................
ESD Ratings ............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Parameter Measurement Information ................ 10
Detailed Description ............................................ 11
9.1
9.2
9.3
9.4
9.5
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
Programming...........................................................
11
11
12
13
13
10 Application and Implementation........................ 14
10.1 Application Information.......................................... 14
10.2 Typical Applications .............................................. 15
11 Power Supply Recommendations ..................... 21
11.1 Self-Powered and Bus-Powered Hubs ................. 21
11.2 Low-Power Bus-Powered and High-Power BusPowered Functions .................................................. 21
11.3 Power Dissipation and Junction Temperature ...... 21
12 Layout................................................................... 23
12.1 Layout Guidelines ................................................. 23
12.2 Layout Example .................................................... 23
13 Device and Documentation Support ................. 24
13.1
13.2
13.3
13.4
13.5
13.6
13.7
Device Support ....................................................
Documentation Support .......................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
24
24
24
24
24
24
24
14 Mechanical, Packaging, and Orderable
Information ........................................................... 24
4 Revision History
Changes from Revision C (May 2019) to Revision D
•
Removed content from the Programming the Current-Limit Threshold section ................................................................... 13
Changes from Revision B (November 2018) to Revision C
•
2
Page
Deleted pending from the Features list items ........................................................................................................................ 1
Changes from Original (January 2018) to Revision A
•
Page
Changed the Storage temperature From: TBD to: MIN = –65°C MAX = 150°C in the Absolute Maximum Ratings ............ 4
Changes from Revision A (May 2018) to Revision B
•
Page
Page
Released to Production ......................................................................................................................................................... 1
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5 Device Comparison Table
MAX
OPERATING
CURRENT
OUTPUT
DISCHARGE
ENABLE
CURRENT LIMIT
LATCH OFF
2
N
High
Adjustable
N
SOT-23 (6)
TPS25221DBV
2
N
High
Adjustable
N
WSON (6)
TPS25221DRV
Package
BASE PART NUMBER
6 Pin Configuration and Functions
DBV PACKAGE
SOT-23 6-Pin
Top View
DRV PACKAGE
WSON 6-Pin
Top View
IN
1
6
OUT
GND
2
5
ILIM
EN
3
4
OUT
1
ILIM
2
FAULT
3
6
IN
5
GND
4
EN
Thermal
Pad
FAULT
Not to scale
Not to scale
Pin Functions
PIN
I/O
DESCRIPTION
NAME
SOT-23
WSON
IN
1
6
I
Input voltage and power switch drain; connect a 0.1 μF or greater
ceramic capacitor from IN to GND close to IC
GND
2
5
--
Ground connection
EN
3
4
I
Enable input, logic high/low turns on power switch
FAULT
4
3
O
Active-low open-drain output, asserted during over-current, or overtemperature conditions
ILIM
5
2
O
External resistor used to set current limit threshold
OUT
6
1
O
Power switch output, connect to load
Thermal Pad
--
PAD
--
Internally connected to GND; used to heat-sink the part to the circuit
board traces. Connect thermal pad to GND pin externally.
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7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
–0.3
6
Voltage range from IN to OUT
–6
6
Continuous FAULT sink current
0
25
mA
ILIM source current
0
1
mA
Voltage range on IN, OUT, EN, FAULT,ILIM
Maximum junction temperature, Tj
V
Internally Limited
Storage temperature, Tstg
(1)
UNIT
–65
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
7.2 ESD Ratings
V(ESD)
(1)
(2)
(3)
Electrostatic discharge
VALUE
UNIT
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2000
V
Charged-device model (CDM), per JEDEC specification JESD22-C101
or ANSI/ESDA/JEDEC JS-002 (2)
±500
V
IEC 61000-4-2 contact discharge (3)
±8000
V
IEC 61000-4-2 air-gap discharge (3)
±15000
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
Surges per EN61000-4-2. 1999 applied to output terminals of EVM. These are passing tests levels, not failure threshold.
7.3 Recommended Operating Conditions
Voltages are respect to GND (unless otherwise noted)
MIN
NOM MAX
UNIT
VIN
Supply voltage
IN
2.5
5.5
V
VEN
Input voltage
EN
0
5.5
V
VIH
High-level input voltage
EN
1.7
VIL
Low-level input voltage
EN
ICON
Output continuous current
OUT
RILIM
Current-limit threshold resistor range (nominal 1%) from ILIM to GND
I/FAULT
Sink current into FAULT
TJ
Operating junction temperature
V
0.66
FAULT
V
0
2
A
20
210
kΩ
0
10
mA
–40
125
°C
7.4 Thermal Information
TPS25221
THERMAL METRIC (1)
DBV (SOT-23)
DRV (WSON)
6-PIN
6-PIN
UNIT
RθJA
Junction-to-ambient thermal resistance
193.2
83
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
127.1
100.5
°C/W
RθJB
Junction-to-board thermal resistance
65.6
46.5
°C/W
ψJT
Junction-to-top characterization parameter
49.0
8.7
°C/W
ψJB
Junction-to-board characterization parameter
65.3
46.4
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
--
24.4
°C/W
(1)
4
Proper thermal design is required to ensure TJ IOS
The device outputs IOS x RLOAD until thermal shutdown. The
fault indicator asserts when the over-current condition
persists for more 8 ms, the fault does not de-assert until
over-current is removed and persists for 8 ms.
TJ > 165 C
The device immediately shuts off the internal power switch
and the fault indicator asserts immediately when the junction
temperature exceeds 165°C (typical). The device has a
thermal hysteresis of 20°C (typical). The fault indicator deasserts when the junction temperature falls below 145°C
(typical).
VIN < 2.37 V
The device immediately shuts off the internal current-limited
switch.
9.5 Programming
9.5.1 Programming the Current-Limit Threshold
The over-current threshold is user programmable through an external resistor. The TPS25221 uses an internal
regulation loop to provide a regulated voltage on the ILIM pin. The current-limit threshold is proportional to the
current sourced out of ILIM. The recommended 1% resistor range for RILIM is 20 kΩ ≤ RILIM ≤ 210 kΩ to ensure
stability of the internal regulation loop. 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 over-current threshold when selecting a value for RILIM. The following equations and Figure 24
can be used to calculate the resulting over-current threshold for a given external resistor value (RILIM). Figure 24
includes current-limit tolerance due to variations caused by temperature and process. However, the equations do
not account for tolerance due to external resistor variation, so it is important to account for this tolerance when
selecting RILIM. The traces routing the RILIM resistor to the TPS25221 must be as short as possible to reduce
parasitic effects on the current-limit accuracy.
RILIM can be selected to provide a current-limit threshold that 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 RILIM and the maximum desired load
current on the IOS(min) curve and choose a value of RILIM below this value. Programming the current limit above a
minimum threshold is important to ensure start-up into full load or heavy capacitive loads. The resulting
maximum current-limit threshold is the intersection of the selected value of RILIM and the IOS(max) curve.
To design below a maximum current-limit threshold, find the intersection of RILIM and the maximum desired load
current on the IOS(max) curve and choose a value of RILIM above this value. Programming the current limit below a
maximum threshold is important to avoid current limiting upstream power supplies, causing the input voltage bus
to droop. The resulting minimum current-limit threshold is the intersection of the selected value of RILIM and the
IOS(min) curve.
Current-Limit Threshold Equation (IOS):
IOSmax (mA) =
52640V
RILIM0.97kW
IOSnom (mA) =
55960V
RILIM1.004kW
IOSmin (mA) =
56850V
RILIM1.033kW
where:
20 kΩ ≤ RILIM ≤ 210 kΩ.
(1)
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Current Limit Threshold-mA
Programming (continued)
3000
2800
2600
2400
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
0
20
IOS(max)
IOS(nom)
IOS(min)
40
60
80 100 120 140 160 180 200 220 235
RILIM-Current Limit Resistor-K:
Curr
Figure 24. Current-Limit Threshold vs Current-Limit Resistor (RILIM)
10 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
10.1 Application Information
10.1.1 Constant-Current
During normal operation, the TPS25221 load current is less than the current-limit threshold and the device is not
limiting current. During normal operation the N-channel MOSFET is fully enhanced, and VOUT = VIN - (IOUT x
rDS(on)). The voltage drop across the MOSFET is relatively small compared to VIN, and VOUT is approximately
equal to VIN.
The TPS25221 limits current to the programmed current-limit threshold, set by RILIM, reducing gate drive to the
internal NFET, which increases Rds(on) and reduces load current. This allows the device to effectively regulate
the current to the current-limit threshold. Increasing the resistance of the MOSFET means that the voltage drop
across the device is no longer negligible (VIN ≠ VOUT), and VOUT decreases. The amount that VOUT decreases is
proportional to the magnitude of the overload condition. The expected VOUT can be calculated by:
IOS × RLOAD
where:
IOS is the current-limit threshold and RLOAD is the magnitude of the overload condition.
(2)
For example, if IOS is programmed to 1 A and a 1 Ω overload condition is applied, the resulting VOUT is 1 V.
While in current limit the power dissipation in the package can raise the die temperature above the thermal
shutdown threshold (145°C typical), and the device turns off until the die temperature decreases by the
hysteresis of the thermal shutdown circuit (20°C typical). The device then turns on and continues to thermal cycle
until the overload condition is removed.
14
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10.2 Typical Applications
10.2.1 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 the Programming the Current-Limit Threshold section). A logiclevel input enables or disables MOSFET Q1 and changes the current-limit threshold by modifying the total
resistance from ILIM to GND. Additional MOSFET and resistor combinations can be used in parallel to Q1/R2 to
increase the number of additional current-limit levels.
NOTE
ILIM must never be driven directly with an external signal.
Input
0.1 mF
Output
IN
OUT
RFAULT
100 kW
CLOAD
R1
210 kW
ILIM
Fault Signal
R2
22.1 kW
FAULT
Control Signal
RLOAD
GND
EN
Thermal Pad
Q1
2N7002
Current Limit
Control Signal
Copyright © 2018, Texas Instruments Incorporated
Figure 25. Two-Level Current-Limit Circuit
10.2.1.1 Design Requirements
For this example, use the parameters shown in Table 2.
Table 2. Design Requirements
PARAMETER
VALUE
Input voltage
5V
Output voltage
5V
Above a minimum current limit
1000 mA
Below a maximum current limit
500 mA
10.2.1.2 Detailed Design Procedures
10.2.1.2.1 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
IOS equations and Figure 24 to select RILIM.
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IOSmin (mA) = 1000mA
IOSmin (mA) =
56850V
RILIM1.033kW
1
æ 56850V ÷ö1.033
÷÷
RILIM (kW) = ççç
çèI
mA ÷ø
OSmin
RILIM (kW) = 50kW
(3)
Select the closest 1% resistor less than the calculated value: RILIM = 49.9 kΩ. This sets the minimum current-limit
threshold at 1 A . Use the IOS equations, Figure 24, and the previously calculated value for RILIM to calculate the
maximum resulting current-limit threshold.
RILIM (kW) = 49.9kW
IOSmax (mA) =
IOSmax (mA) =
52640V
RILIM0.97kW
52640V
49.90.97kW
IOSmax (mA) = 1186mA
(4)
The resulting maximum current-limit threshold is 1186 mA with a 49.9 kΩ resistor.
10.2.1.2.2 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 500 mA to protect an up-stream power supply. Use
the IOS equations and Figure 24 to select RILIM.
IOSmax (mA) = 500mA
IOSmax (mA) =
52640V
RILIM0.97kW
1
æ 52640V ÷ö0.97
÷÷
RILIM (kW) = ççç
çèI
mA ÷ø
OSmax
RILIM (kW) = 121.6kW
(5)
Select the closest 1% resistor greater than the calculated value: RILIM = 124 kΩ. This sets the maximum currentlimit threshold at 500 mA . Use the IOS equations, Figure 24, and the previously calculated value for RILIM to
calculate the minimum resulting current-limit threshold.
RILIM (kW) = 124kW
IOSmin (mA) =
IOSmin (mA) =
56850V
RILIM1.033kW
56850V
1241.033kW
IOSmin (mA) = 391mA
(6)
The resulting minimum current-limit threshold is 391 mA with a 124 kΩ resistor.
10.2.1.2.3 Accounting for Resistor Tolerance
The previous sections described the selection of RILIM given certain application requirements and the importance
of understanding the current-limit threshold tolerance. The analysis focused only on TPS25221 performance and
assumed an exact resistor value. However, resistors sold in quantity are not exact and are bounded by an upper
and lower tolerance centered around a nominal resistance. The additional RILIM resistance tolerance directly
affects the current-limit threshold accuracy at a system level. The following table shows a process that accounts
16
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for worst-case resistor tolerance assuming 1% resistor values. Step one follows the selection process outlined in
the application examples above. Step two determines the upper and lower resistance bounds of the selected
resistor. Step three uses the upper and lower resistor bounds in the IOS equations to calculate the threshold
limits. It is important to use tighter tolerance resistors, for example, 0.5% or 0.1%, when precision current limiting
is desired.
Table 3. Common RILIM Resistor Selections
DESIRED
NOMINAL
CURRENT
LIMIT
(mA)
IDEAL
RESISTOR
(kΩ)
CLOSEST
1% RESISTOR
(kΩ)
RESISTOR TOLERANCE
ACTUAL LIMITS
1% LOW (kΩ)
1% HIGH (kΩ)
IOS(min) (mA)
IOS(nom) (mA)
IOS(max) (mA)
275
199.2
200
198
202
236
274
312
400
137.2
137
135.6
138.4
349
401
450
500
109.8
110
108.9
111.1
438
499
556
600
91.6
90.9
90.0
91.8
533
605
669
700
78.6
78.7
77.9
79.5
619
699
770
800
68.8
68.1
67.4
68.8
719
808
886
900
61.2
61.9
61.3
62.5
793
889
972
1000
55.1
54.9
54.4
55.4
898
1003
1092
1200
45.9
46.4
45.9
46.9
1068
1188
1285
1400
39.4
39.2
38.8
39.6
1272
1407
1514
1600
34.5
34.8
34.5
35.1
1438
1585
1699
1800
30.7
30.9
30.6
31.2
1626
1786
1907
2000
27.6
27.4
27.1
27.7
1841
2015
2143
2200
25.1
24.9
24.7
25.1
2032
2219
2351
2400
23.0
23.2
23.0
23.4
2186
2382
2518
2600
21.3
21.5
21.3
21.7
2365
2571
2711
2700
20.5
20.5
20.3
20.7
2484
2697
2839
10.2.1.2.4 Input and Output Capacitance
Input and output capacitance improves the performance of the device; the actual capacitance must be optimized
for the particular application. For all applications, TI recommends placing a 0.1 µF or greater ceramic bypass
capacitor between IN and GND 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
transient conditions. This is especially important during bench testing when long, inductive cables are used to
connect the evaluation board to the bench power-supply.
TI recommends placing a high-value electrolytic capacitor on the output pin when large transient currents are
expected on the output.
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10.2.1.3 Application Curve
VIN = 5 V, RILIM = 20 kΩ, ROUT = 5 Ω
Figure 26. Turnon Delay and Rise Time
10.2.2 Auto-Retry Functionality
Some applications require that an over-current 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 CRETRY to begin charging. The part re-enables when the voltage
on EN reaches the turn-on threshold, and the auto-retry time is determined by the resistor-capacitor time
constant. The device continues to cycle in this manner until the fault condition is removed.
Input
TPS25221
0.1 mF
Output
IN
OUT
RLOAD
RFAULT
CLOAD
100 kW
ILIM
FAULT
EN
GND
RILIM
20 kW
CRETRY
0.1 mF
Thermal Pad
Copyright © 2018, Texas Instruments Incorporated
Figure 27. Auto-Retry Functionality
Some applications require auto-retry functionality and the ability to enable or disable with an external logic signal.
Figure 28 shows how an external logic signal can drive EN through RFAULT and maintain auto-retry functionality.
The resistor-capacitor time constant determines the auto-retry time-out period.
18
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TPS25221
Input
0.1 mF
Output
IN
OUT
RLOAD
CLOAD
External Logic
Signal & Driver
ILIM
RFAULT
RILIM
FAULT
100 kW
20 kW
GND
EN
CRETRY
Thermal Pad
0.1 mF
Copyright © 2018, Texas Instruments Incorporated
Figure 28. Auto-Retry Functionality With External EN Signal
10.2.2.1 Design Requirements (added)
For this example, use the parameters shown in Table 4.
Table 4. Design Requirements
PARAMETER
VALUE
Input voltage
5V
Output voltage
5V
Above a minimum current limit
1000 mA
Below a maximum current limit
500 mA
10.2.2.2 Detailed Design Procedure
Refer to Programming the Current-Limit Threshold section for the current limit setting. For auto-retry functionality,
once FAULT asserted, EN pull low, TPS25221 is disabled, FAULT des-asserted, CRETRY is slowly charged to EN
logic high through RFAULT, then enable, after deglitch time, FAULT asserted again. In the event of an overload,
TPS25221 cycles and has output average current. ON-time with output current is decided by FAULT deglitch
time. OFF-time without output current is decided by RFAULT x CRETRY constant time to EN logic high and ton time.
Therefore, set the RFAULT × CRETRY to get the desired output average current during overload.
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10.2.3 Typical Application as USB Power Switch
TPS25221
5V USB
Input
0.1 mF
USB Data
IN
OUT
USB
Port
RFAULT
100 kW
120 mF
FAULT
EN
Fault Signal
Control Signal
ILIM
GND
Thermal Pad
RILIM
20 kW
USB requirement only*
*USB requirement that downstream
facing ports are bypassed with at least
120 mF per hub
Copyright © 2018, Texas Instruments Incorporated
Figure 29. Typical Application as USB Power Switch
10.2.3.1 Design Requirements
For this example, use the parameters shown in Table 5.
Table 5. Design Requirements
PARAMETER
VALUE
Input voltage
5V
Output voltage
5V
Current
1200 mA
10.2.3.1.1 USB Power-Distribution Requirements
USB can be implemented in several ways regardless of the type of USB device being developed. Several powerdistribution features must be implemented.
• Self Powered Hub (SPH) must:
– Current limit downstream ports
– Report over-current conditions
• Bus Powered Hub (BPH) must:
– Enable or disable power to downstream ports
– Power up at
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