TPS2045 [TI]
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES; 电流限制的配电开关
| 型号： | TPS2045 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES |
| 文件： | 总23页 (文件大小：407K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
features
typical applications
135-mΩ -Maximum (5-V Input) High-Side
MOSFET Switch
Notebook, Desktop and Palmtop PCs
Monitors, Keyboards, Scanners, and
Printers
250 mA Continuous Current
Short-Circuit and Thermal Protection With
Overcurrent Logic Output
Digital Cameras, Phones, and PBXs
Hot-Insertion Applications
Operating Range . . . 2.7-V to 5.5-V
Logic-Level Enable Input
TPS2045
D OR P PACKAGE
(TOP VIEW)
TPS2055
D OR P PACKAGE
(TOP VIEW)
2.5-ms Typical Rise Time
Undervoltage Lockout
GND
IN
OUT
OUT
OUT
OC
GND
IN
OUT
OUT
OUT
OC
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
10 µA Maximum Standby Supply Current
Bidirectional Switch
IN
IN
Available in 8-pin SOIC and PDIP Packages
Ambient Temperature Range, –40°C to 85°C
EN
EN
2-kV Human-Body-Model, 200-V
Machine-Model ESD Protection
description
The TPS2045 and TPS2055 power-distribution switches are intended for applications where heavy capacitive
loads and short circuits are likely. Each of these 135-mΩ N-channel MOSFET high-side power switches is
controlledbyalogicenablecompatiblewith5-Vand3-Vlogic. Gatedriveisprovidedbyaninternalchargepump
that controls the power-switch rise times and fall times to minimize current surges during switching. The charge
pump requires no external components and allows operation from supplies as low as 2.7 V.
When the output load exceeds the current-limit threshold or a short is present, the TPS2045 and TPS2055 limit
the output current to a safe level by switching into a constant-current mode, pulling the overcurrent (OC) logic
output low. When continuous heavy overloads and short circuits increase the power dissipation in the switch,
causingthejunctiontemperaturetorise, athermalprotectioncircuitshutsofftheswitchinovercurrenttoprevent
damage. Recovery from a thermal shutdown is automatic once the device has cooled sufficiently. Internal
circuitry ensures the switch remains off until valid input voltage is present.
The TPS2045 and TPS2055 are designed to limit at 0.44-A load. These power-distribution switches, available
in 8-pin small-outline integrated circuit (SOIC) and 8-pin plastic dual-in-line packages (PDIP), operate over an
ambient temperature range of –40°C to 85°C.
AVAILABLE OPTIONS
RECOMMENDED
MAXIMUM CONTINUOUS
LOAD CURRENT
(A)
PACKAGED DEVICES
TYPICAL SHORT-CIRCUIT
CURRENT LIMIT AT 25°C
(A)
T
A
ENABLE
SOIC
PDIP
(P)
†
(D)
–40°C to 85°C Active low
–40°C to 85°C Active high
0.25
0.25
0.44
0.44
TPS2045D TPS2045P
TPS2055D TPS2055P
†
The D package is available taped and reeled. Add an R suffix to device type (e.g., TPS2045DR)
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.
Copyright 1999, Texas Instruments Incorporated
This document contains information on products in more than one phase
of development. The status of each device is indicated on the page(s)
specifying its electrical characteristics.
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
TPS2045 functional block diagram
Power Switch
†
CS
IN
OUT
Charge
Pump
Current
Limit
EN
Driver
OC
UVLO
Thermal
Sense
GND
†
Current Sense
Terminal Functions
TERMINAL
NO.
I/O
DESCRIPTION
NAME
D OR P
TPS2045
TPS2055
EN
4
–
–
4
I
I
Enable input. Logic low turns on power switch.
Enable input. Logic high turns on power switch.
Ground
EN
GND
IN
1
1
I
2, 3
5
2, 3
5
I
Input voltage
OC
OUT
O
O
Over current. Logic output active low
Power-switch output
6, 7, 8
6, 7, 8
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
detailed description
power switch
The power switch is an N-channel MOSFET with a maximum on-state resistance of 135 mΩ (V
= 5 V).
I(IN)
Configured as a high-side switch, the power switch prevents current flow from OUT to IN and IN to OUT when
disabled. The power switch can supply a minimum of 250 mA per switch.
charge pump
An internal 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 2.7 V and requires
very little supply current.
driver
The driver controls the gate voltage of the power switch. To limit large current surges and reduce the associated
electromagnetic interference (EMI) produced, the driver incorporates circuitry that controls the rise times and
fall times of the output voltage. The rise and fall times are typically in the 2-ms to 4-ms range.
enable (EN or EN)
Thelogicenabledisablesthepowerswitchandthebiasforthechargepump, driver, andothercircuitrytoreduce
the supply current to less than 10 µA when a logic high is present on EN (TPS2045) or a logic low is present
on EN (TPS2055). A logic zero input on EN or a logic high on EN restores bias to the drive and control circuits
and turns the power on. The enable input is compatible with both TTL and CMOS logic levels.
overcurrent (OC)
The OC open-drain output is asserted (active low) when an overcurrent or overtemperature condition is
encountered. The output will remain asserted until the overcurrent or overtemperature condition is removed.
current sense
A sense FET monitors the current supplied to the load. The sense FET measures current more efficiently than
conventional resistance methods. When an overload or short circuit is encountered, the current-sense circuitry
sends a control signal to the driver. The driver in turn reduces the gate voltage and drives the power FET into
its saturation region, which switches the output into a constant current mode and holds the current constant
while varying the voltage on the load.
thermal sense
An internal thermal-sense circuit shuts off the power switch when the junction temperature rises to
approximately 140°C. Hysteresis is built into the thermal sense circuit. After the device has cooled
approximately 20°C, the switch turns back on. The switch continues to cycle off and on until the fault is removed.
undervoltage lockout
A voltage sense circuit monitors the input voltage. When the input voltage is below approximately 2 V, a control
signal turns off the power switch.
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
†
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Input voltage range, V
Output voltage range, V
Input voltage range, V
Continuous output current, I
(see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6 V
I(IN)
(see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to V
+ 0.3 V
O(OUT)
I(EN)
I(IN)
or V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6 V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . internally limited
I(EN)
O(OUT)
Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Dissipation Rating Table
Operating virtual junction temperature range, T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to 125°C
J
Storage temperature range, T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C
stg
Lead temperature soldering 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . 260°C
Electrostatic discharge (ESD) protection: Human body model MIL-STD-883C . . . . . . . . . . . . . . . . . . . . . 2 kV
Machine model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 kV
†
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.
NOTE 1: All voltages are with respect to GND.
DISSIPATION RATING TABLE
DERATING FACTOR
T
≤ 25°C
T
A
= 70°C
T = 85°C
A
A
PACKAGE
POWER RATING
ABOVE T = 25°C
POWER RATING POWER RATING
A
D
P
725 mW
5.8 mW/°C
9.4 mW/°C
464 mW
752 mW
377 mW
611 mW
1175 mW
recommended operating conditions
TPS2045
TPS2055
UNIT
MIN
2.7
0
MAX
5.5
MIN
2.7
0
MAX
Input voltage, V
Input voltage, V
5.5
5.5
V
V
I(IN)
or V
5.5
I(EN)
I(EN)
Continuous output current, I
O(OUT)
0
250
125
0
250
125
mA
°C
Operating virtual junction temperature, T
–40
–40
J
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
electrical characteristics over recommended operating junction temperature range, V
= 5.5 V,
I(IN)
I = rated current, V
= 0 V, V
= Hi (unless otherwise noted)
O
I(EN)
I(EN)
power switch
TPS2045
†
TPS2055
TYP
PARAMETER
UNIT
TEST CONDITIONS
MIN
TYP
MAX
MIN
MAX
V
= 5 V,
T = 25°C,
J
I(IN)
= 0.25 A
80
95
80
90
95
I
O
Static drain-source on-state
resistance, 5-V operation
V
= 5 V,
T = 85°C,
J
I(IN)
= 0.25 A
90
100
85
120
135
105
135
150
120
135
105
135
150
I
O
V
= 5 V,
T = 125°C,
J
I(IN)
= 0.25 A
100
85
mΩ
I
O
r
DS(on)
V
= 3.3 V, T = 25°C,
J
= 0.25 A
I(IN)
I(IN)
I(IN)
I(IN)
I
O
Static drain-source on-state
resistance, 3.3-V operation
V
= 3.3 V, T = 85°C,
J
= 0.25 A
100
115
2.5
3
100
115
2.5
3
I
O
V
= 3.3 V, T = 125°C,
J
= 0.25 A
I
O
V
C
= 5.5 V, T = 25°C,
J
= 1 µF,
R = 20 Ω
L
L
t
t
Rise time, output
Fall time, output
ms
ms
r
V
C
= 2.7 V, T = 25°C,
J
= 1 µF,
I(IN)
R = 20 Ω
L
L
V
C
= 5.5 V, T = 25°C,
J
I(IN)
L
4.4
2.5
4.4
2.5
= 1 µF,
R = 20 Ω
L
f
V
C
= 2.7 V, T = 25°C,
J
I(IN)
= 1 µF,
R = 20 Ω
L
L
†
Pulse-testing techniques maintain junction temperature close to ambient temperature; thermal effects must be taken into account separately.
enable input EN or EN
TPS2045
MIN TYP
TPS2055
MIN TYP
PARAMETER
TEST CONDITIONS
UNIT
MAX
MAX
V
V
High-level input voltage
Low-level input voltage
2.7 V ≤ V
4.5 V ≤ V
2.7 V ≤ V
≤ 5.5 V
≤ 5.5 V
≤ 4.5 V
2
2
V
V
IH
I(IN)
I(IN)
I(IN)
0.8
0.4
0.5
0.8
0.4
IL
TPS2045
TPS2055
V
V
= 0 V or V
= V
–0.5
I(EN)
I(EN)
or V
I(IN)
= 0 V
I
I
Input current
µA
= V
–0.5
0.5
20
40
I(EN)
I(IN)
I(EN)
t
t
Turnon time
Turnoff time
C
C
= 100 µF,
= 100 µF,
R
R
= 20 Ω
= 20 Ω
20
40
ms
on
L
L
L
L
off
current limit
TPS2045
MIN TYP
TPS2055
MIN TYP
†
PARAMETER
UNIT
TEST CONDITIONS
MAX
MAX
V
= 5 V, OUT connected to GND,
I(IN)
Device enabled into short circuit
I
Short-circuit output current
0.345
0.44 0.525 0.345
0.44 0.525
A
OS
†
Pulse-testing techniques maintain junction temperature close to ambient temperature; thermal effects must be taken into account separately.
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
electrical characteristics over recommended operating junction temperature range, V
= 5.5 V,
I(IN)
I = rated current, V
= 0 V, V
= Hi (unless otherwise noted) (continued)
O
I(EN)
I(EN)
supply current
TPS2045
TPS2055
MIN TYP MAX
PARAMETER
TEST CONDITIONS
T = 25°C
UNIT
MIN
TYP MAX
0.015
1
J
Supply
TPS2045
TPS2055
TPS2045
TPS2055
V
V
= V
I(EN)
I(IN)
–40°C ≤ T ≤ 125°C
10
No Load
on OUT
J
current,
low-level
output
µA
µA
T = 25°C
0.015
1
J
= 0 V
= 0 V
I(EN)
–40°C ≤ T ≤ 125°C
10
J
T = 25°C
J
80
100
Supply
V
V
I(EN)
–40°C ≤ T ≤ 125°C
100
No Load
on OUT
J
current,
high-level
output
T = 25°C
80
100
J
= V
= V
I(EN)
I(IN)
I(IN)
–40°C ≤ T ≤ 125°C
100
J
OUT
connected
to ground
V
I(EN)
V
I(EN)
V
I(EN)
V
I(EN)
–40°C ≤ T ≤ 125°C TPS2045
100
0.3
J
Leakage
current
µA
µA
= 0 V
= 0 V
= Hi
–40°C ≤ T ≤ 125°C TPS2055
100
0.3
J
Reverse
leakage
current
TPS2045
IN = high
impedance
T = 25°C
J
TPS2055
undervoltage lockout
TPS2045
TYP
TPS2055
TYP MAX
PARAMETER
TEST CONDITIONS
UNIT
MIN
MAX
MIN
Low-level input voltage
2
2.5
2
2.5
V
Hysteresis
T = 25°C
J
100
100
mV
overcurrent OC
TPS2045
TYP
TPS2055
TYP
PARAMETER
TEST CONDITIONS
UNIT
MIN
MAX
10
MIN
MAX
10
†
Sink current
V
= 5 V
mA
V
O
Output low voltage
I
= 5 V,
V
0.5
1
0.5
1
O
OL(OC)
= 3.3 V
†
Off-state current
†
V
= 5 V,
V
µA
O
O
Specified by design, not production tested.
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
PARAMETER MEASUREMENT INFORMATION
OUT
t
t
f
r
RL
CL
V
90%
10%
O(OUT)
90%
10%
TEST CIRCUIT
50%
90%
50%
50%
50%
V
V
I(EN)
I(EN)
t
t
off
t
t
on
off
on
90%
V
V
O(OUT)
O(OUT)
10%
10%
VOLTAGE WAVEFORMS
Figure 1. Test Circuit and Voltage Waveforms
V
I(EN)
(5 V/div)
V
I(EN)
(5 V/div)
V
T
C
= 5 V
= 25°C
= 0.1 µF
V
T
C
= 5 V
= 25°C
= 0.1 µF
I(IN)
A
L
I(IN)
A
L
V
O(OUT)
(2 V/div)
V
O(OUT)
(2 V/div)
0
1000
2000
3000
4000
5000
0
1
2
3
4
5
6
7
8
9
10
t – Time – ms
t – Time – ms
Figure 2. Turnon Delay and Rise Time
Figure 3. Turnoff Delay and Fall Time
with 0.1-µF Load
with 0.1-µF Load
7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
PARAMETER MEASUREMENT INFORMATION
V
V
I(EN)
(5 V/div)
I(EN)
(5 V/div)
V
= 5 V
I(IN)
= 25°C
V
= 5 V
I(IN)
= 25°C
T
A
T
A
V
O(OUT)
(2 V/div)
V
C
R
= 1 µF
= 20 Ω
O(OUT)
(2 V/div)
L
L
C
R
= 1 µF
= 20 Ω
L
L
0
1
2
3
4
5
6
7
8
9
10
0
2
4
6
8
10 12 14 16 18 20
t – Time – ms
t – Time – ms
Figure 4. Turnon Delay and Rise Time
Figure 5. Turnoff Delay and Fall Time
with 1-µF Load
with 1-µF Load
V
T
A
= 5 V
I(IN)
= 25°C
V
T
A
= 5 V
I(IN)
= 25°C
V
I(EN)
(5 V/div)
V
O(OUT)
(2 V/div)
I
I
O(OUT)
O(OUT)
(0.2 A/div)
(0.5 A/div)
0
1
2
3
4
5
6
7
8
9
10
0
10 20 30 40 50 60 70 80 90 100
t – Time – ms
t – Time – ms
Figure 6. TPS2045, Short-Circuit Current,
Device Enabled into Short
Figure 7. TPS2045, Threshold Trip Current
with Ramped Load on Enabled Device
8
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
PARAMETER MEASUREMENT INFORMATION
V
= 5 V
I(IN)
= 25°C
T
A
R
= 20 Ω
L
V
V
O(OC)
(5 V/div)
I(EN)
(5 V/div)
220 µF
47 µF
100 µF
I
O(OUT)
(0.5 A/div)
I
V
T
= 5 V
O(OUT)
I(IN)
= 25°C
(0.2 A/div)
A
0
2
4
6
8
10 12 14 16 18 20
0
20 40 60 80 100 120 140 160 180 200
t – Time – ms
t – Time – ms
Figure 8. Inrush Current with 220-µF, 100-µF
and 47-µF Load Capacitance
Figure 9. Ramped Load on Enabled Device
V
T
A
= 5 V
V
= 5 V
I(IN)
= 25°C
I(IN)
T = 25°C
A
V
V
O(OC)
O(OC)
(5 V/div)
(5 V/div)
I
I
O(OUT)
O(OUT)
(0.5 A/div)
(0.5 A/div)
0
200
400
600
800
1000
0
200
400
600
800
1000
t – Time – µs
t – Time – µs
Figure 10. 4-Ω Load Connected
Figure 11. 1-Ω Load Connected
to Enabled Device
to Enabled Device
9
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
TYPICAL CHARACTERISTICS
TURNON DELAY
vs
INPUT VOLTAGE
TURNOFF DELAY
vs
INPUT VOLTAGE
6
5.5
5
15
13
11
C
R
T
= 1 µF
= 20 Ω
= 25°C
C
R
T
= 1 µF
= 20 Ω
= 25°C
L
L
A
L
L
A
4.5
4
9
7
3.5
3
2.5
3
3.5
4
4.5
5
5.5
6
2.5
3
3.5
4
4.5
5
5.5
6
V – Input Voltage – V
I
V – Input Voltage – V
I
Figure 12
Figure 13
RISE TIME
vs
FALL TIME
vs
LOAD CURRENT
LOAD CURRENT
2.7
2.6
2.5
2.85
2.8
V
T
= 5 V
= 25°C
V
T
= 5 V
I (IN)
A
I (IN)
= 25°C
A
2.75
2.4
2.3
2.7
2.65
0
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
0
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
– Load Current – A
I
L
– Load Current – A
I
L
Figure 14
Figure 15
10
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
TYPICAL CHARACTERISTICS
SUPPLY CURRENT, OUTPUT ENABLED
SUPPLY CURRENT, OUTPUT DISABLED
vs
vs
JUNCTION TEMPERATURE
JUNCTION TEMPERATURE
200
180
160
2000
1800
V
= 5.5 V
I(IN)
V
= 5.5 V
= 5 V
1600
1400
I(IN)
V
I(IN)
= 5 V
V
I(IN)
V
= 4 V
I(IN)
1200
1000
800
V
I(IN)
= 4 V
V
I(IN)
= 2.7 V
V
= 2.7 V
I(IN)
140
120
100
600
V
= 3.3 V
I(IN)
400
200
0
–200
–50 –25
0
25
50
75 100 125 150
–50 –25
0
25
50
75
100 125 150
T
J
– Junction Temperature – °C
T
J
– Junction Temperature – °C
Figure 16
Figure 17
SUPPLY CURRENT, OUTPUT ENABLED
SUPPLY CURRENT, OUTPUT DISABLED
vs
vs
INPUT VOLTAGE
INPUT VOLTAGE
200
180
160
2000
1600
T
J
= 125°C
T
J
= 125°C
T
J
= 85°C
1200
800
T
J
= 25°C
140
T
J
= 0°C
400
0
T
J
= 25°C
T
4
= 85°C
J
T
J
= –40°C
120
100
T
J
= –40°C
T
J
= 0°C
–400
2.5
3
3.5
4
4.5
5
5.5
6
2.5
3
3.5
4.5
5
5.5
6
V – Input Voltage – V
I
V – Input Voltage – V
I
Figure 18
Figure 19
11
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TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
TYPICAL CHARACTERISTICS
STATIC DRAIN-SOURCE ON-STATE RESISTANCE
STATIC DRAIN-SOURCE ON-STATE RESISTANCE
vs
vs
JUNCTION TEMPERATURE
INPUT VOLTAGE
175
150
125
175
150
125
I
O
= 0.25 A
I
O
= 0.25 A
V
= 2.7 V
I(IN)
V
I(IN)
= 3.3 V
T
J
= 125°C
T
J
= 85°C
100
75
100
75
V
I(IN)
= 4.5 V
T
J
= 25°C
T
J
= 0°C
V
I(IN)
= 5 V
T
J
= –40°C
50
–50 –25
50
2.5
0
25
50
75
100 125 150
3
3.5
4
4.5
5
5.5
6
T
J
– Junction Temperature – °C
V – Input Voltage – V
I
Figure 20
Figure 21
INPUT-TO-OUTPUT VOLTAGE
SHORT-CURCUIT OUTPUT CURRENT
vs
vs
LOAD CURRENT
INPUT VOLTAGE
45
490
T
A
= 25°C
40
35
30
25
20
15
10
470
450
V
= 2.7 V
I(IN)
T
= –40°C
J
V
= 3.3 V
I(IN)
T
J
= 25°C
430
410
390
370
350
T
J
= 125°C
V
= 4.5 V
I(IN)
V
I(IN)
= 5 V
5
0
0.1
0.14
0.18
0.22
0.26
0.3
2.5
3
3.5
4
4.5
5
5.5
I
L
– Load Current – A
V – Input Voltage – V
I
Figure 22
Figure 23
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TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
TYPICAL CHARACTERISTICS
THRESHOLD TRIP CURRENT
SHORTCIRCUIT OUTPUT CURRENT
vs
vs
INPUT VOLTAGE
JUNCTION TEMPERATURE
0.73
0.71
450
T
= 25°C
A
V
= 5 V
Load Ramp = 1 A/10 ms
I(IN)
445
440
435
430
425
420
415
V
I(IN)
= 4 V
V
= 2.7 V
I(IN)
0.69
0.67
0.65
410
405
2.5
3
3.5
4
4.5
5
5.5
6
–50 –25
0
25
50
75
100
125
V – Input Voltage – V
I
T
J
– Junction Temperature – °C
Figure 24
Figure 25
UNDERVOLTAGE LOCKOUT
vs
CURRENT-LIMIT RESPONSE
vs
JUNCTION TEMPERATURE
PEAK CURRENT
2.5
2.4
500
350
250
100
0
V
T
A
= 5 V
I(IN)
= 25°C
Start Threshold
Stop Threshold
2.3
2.2
2.1
2
–50 –25
0
25
50
75
100 125 150
0
2
4
6
8
10
T
J
– Junction Temperature – °C
Peak Current – A
Figure 26
Figure 27
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SLVS182 – APRIL 1999
TYPICAL CHARACTERISTICS
OVERCURRENT (OC) RESPONSE TIME
vs
PEAK CURRENT
10
V
T
A
= 5 V
I(IN)
= 25°C
8.5
7
5.5
4
0
2
4
6
8
10
Peak Current – A
Figure 28
APPLICATION INFORMATION
TPS2045
2,3
Power Supply
2.7 V to 5.5 V
IN
6,7,8
Load
OUT
0.1 µF
0.1 µF
22 µF
5
4
OC
EN
GND
1
Figure 29. Typical Application
power-supply considerations
A 0.01-µF to 0.1-µF ceramic bypass capacitor between IN and GND, close to the device, is recommended.
Placing a high-value electrolytic capacitor on the output pin(s) is recommended when the output load is heavy.
This precaution reduces power-supply transients that may cause ringing on the input. Additionally, bypassing
the output with a 0.01-µF to 0.1-µF ceramic capacitor improves the immunity of the device to short-circuit
transients.
14
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APPLICATION INFORMATION
overcurrent
A sense FET is employed to check for overcurrent conditions. Unlike current-sense resistors, sense FETs do
not increase the series resistance of the current path. When an overcurrent condition is detected, the device
maintains a constant output current and reduces the output voltage accordingly. Complete shutdown occurs
only if the fault is present long enough to activate thermal limiting.
Three possible overload conditions can occur. In the first condition, the output has been shorted before the
device is enabled or before V
and immediately switch into a constant-current output.
has been applied (see Figure 6). The TPS2045 and TPS2055 sense the short
I(IN)
In the second condition, the short occurs while the device is enabled. At the instant the short occurs, very high
currents may flow for a short time before the current-limit circuit can react. After the current-limit circuit has
tripped (reached the overcurrent trip threshhold) the device switches into constant-current mode.
In the third condition, the load has been gradually increased beyond the recommended operating current. The
current is permitted to rise until the current-limit threshold is reached or until the thermal limit of the device is
exceeded (see Figure 7). The TPS2045 and TPS2055 are capable of delivering current up to the current-limit
threshold without damaging the device. Once the threshold has been reached, the device switches into its
constant-current mode.
OC response
The OC open-drain output is asserted (active low) when an overcurrent or overtemperature condition is
encountered. The output will remain asserted until the overcurrent or overtemperature condition is removed.
Connectingaheavycapacitiveloadtoanenableddevicecancausemomentaryfalseovercurrentreportingfrom
the inrush current flowing through the device, charging the downstream capacitor. An RC filter of 500 µs (see
Figure 30) can be connected to the OC pin to reduce false overcurrent reporting caused by hot-plug switching
events or extremely high capacitive loads. Using low-ESR electrolytic capacitors on the output lowers the inrush
current flow through the device during hot-plug events by providing a low impedance energy source, thereby
reducing erroneous overcurrent reporting.
TPS2045
TPS2045
GND
V+
V+
GND
OUT
OUT
OUT
OC
OUT
OUT
OUT
OC
R
pullup
IN
IN
R
pullup
IN
IN
R
filter
To USB
EN
EN
Controller
C
filter
Figure 30. Typical Circuit for OC Pin and RC Filter for Damping Inrush OC Responses
15
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SLVS182 – APRIL 1999
APPLICATION INFORMATION
power dissipation and junction temperature
The low on-resistance on the n-channel MOSFET allows small surface-mount packages, such as SOIC, to pass
large currents. The thermal resistances of these packages are high compared to those of power packages; it
is good design practice to check power dissipation and junction temperature. The first step is to find r
the input voltage and operating temperature. As an initial estimate, use the highest operating ambient
at
DS(on)
temperature of interest and read r
from Figure 21. Next, calculate the power dissipation using:
DS(on)
2
P
r
I
D
DS(on)
Finally, calculate the junction temperature:
T
P
R
T
J
D
JA
A
Where:
T = Ambient Temperature °C
A
θJA
R
= Thermal resistance SOIC = 172°C/W, PDIP = 106°C/W
Compare the calculated junction temperature with the initial estimate. If they do not agree within a few degrees,
repeat the calculation, using the calculated value as the new estimate. Two or three iterations are generally
sufficient to get a reasonable answer.
thermal protection
Thermal protection prevents damage to the IC when heavy-overload or short-circuit faults are present for
extendedperiodsoftime. ThefaultsforcetheTPS2045andTPS2055intoconstantcurrentmode, whichcauses
the voltage across the high-side switch to increase; under short-circuit conditions, the voltage across the switch
is equal to the input voltage. The increased dissipation causes the junction temperature to rise to high levels.
The protection circuit senses the junction temperature of the switch and shuts it off. Hysteresis is built into the
thermal sense circuit, and after the device has cooled approximately 20 degrees, the switch turns back on. The
switch continues to cycle in this manner until the load fault or input power is removed.
undervoltage lockout (UVLO)
Anundervoltagelockoutensuresthatthepowerswitchisintheoffstateatpowerup. Whenevertheinputvoltage
falls below approximately 2 V, the power switch will be quickly turned off. This facilitates the design of
hot-insertion systems where it is not possible to turn off the power switch before input power is removed. The
UVLO will also keep the switch from being turned on until the power supply has reached at least 2 V, even if
the switch is enabled. Upon reinsertion, the power switch will be turned on, with a controlled rise time to reduce
EMI and voltage overshoots.
16
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APPLICATION INFORMATION
Universal Serial Bus (USB) applications
The Universal Serial Bus (USB) interface is 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). 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 defines the following five classes of devices, each differentiated by power-consumption
requirements:
Hosts/self-powered hubs (SPH)
Bus-powered hubs (BPH)
Low-power, bus-powered functions
High-power, bus-powered functions
Self-powered functions
Self-powered and bus-powered hubs distribute data and power to downstream functions. The TPS2045 and
TPS2055 can provide power-distribution solutions for many of these classes of devices.
Bus-powered hubs obtain all power from upstream ports and often contain an embedded function. The hubs
are required to power up with less than one unit load. 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
can be 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
one unit load. 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 functions 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 µF at power up, the device must implement inrush current limiting (see Figure 31).
Power Supply
D+
3.3 V
TPS2045
D–
2,3
V
IN
BUS
GND
6, 7, 8
10 µF
0.1 µF
Internal
Function
OUT
0.1 µF
10 µF
5
4
OC
EN
USB
Control
GND
1
Figure 31. High-Power Bus-Powered Function
17
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CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
APPLICATION INFORMATION
USB power-distribution requirements
USB can be implemented in several ways, and, regardless of the type of USB device being developed, several
power distribution features must be implemented.
Bus-Powered Hubs must:
–
–
–
Enable/disable power to downstream ports
Power up at <100 mA
Limit inrush current (<44 Ω and 10 µF)
Functions must:
–
–
Limit inrush currents
Power up at <100 mA
The feature set of the TPS2045 and TPS2055 allows them to meet each of these requirements. The integrated
current-limiting and overcurrent reporting is required by hosts and self-powered hubs. The logic-level enable
and controlled rise times meet the need of both input and output ports on bus-power hubs, as well as the input
ports for bus-power functions (see Figure 32).
18
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SLVS182 – APRIL 1999
APPLICATION INFORMATION
TUSB2040
Hub Controller
BUSPWR
SN75240
Downstream
Upstream
Port
A
B
C
D
Ports
GANGED
DP1
DM1
D +
D –
DP0
DM0
D +
D –
Ferrite Beads
A
B
C
D
GND
5 V
GND
SN75240
DP2
DM2
†
33 µF
DP3
DM3
5 V
D +
D –
A
B
C
D
1 µF
Ferrite Beads
TPS76333
IN
SN75240
GND
DP4
DM4
0.1 µF
4.7 µF
V
3.3 V
GND
5 V
†
CC
4.7 µF
TPS2045
PWRON1
EN
OC
IN
GND
33 µF
OVRCUR1
0.1 µF
0.1 µF
0.1 µF
OUT
IN
D +
D –
TPS2045
48-MHz
Crystal
PWRON2
EN
OC
XTAL1
XTAL2
Ferrite Beads
OVRCUR2
GND
5 V
OUT
IN
Tuning
Circuit
TPS2045
PWRON3
EN
OC
†
33 µF
OVRCUR3
OCSOFF
GND
OUT
IN
D +
D –
TPS2045
Ferrite Beads
PWRON4
EN
OC
GND
5 V
0.1 µF
OVRCUR4
OUT
†
33 µF
†
USB rev 1.1 requires 120 µF per hub.
Figure 32. Bus-Powered Hub Implementation
19
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SLVS182 – APRIL 1999
APPLICATION INFORMATION
generic hot-plug applications (see Figure 33)
In many applications it may be necessary to remove modules or pc boards while the main unit is still operating.
These are considered hot-plug applications. Such implementations require the control of current surges seen
by the main power supply and the card being inserted. The most effective way to control these surges is to limit
and slowly ramp the current and voltage being applied to the card, similar to the way in which a power supply
normally turns on. Due to the controlled rise times and fall times of the TPS2045 and TPS2055, these devices
can be used to provide a softer start-up to devices being hot-plugged into a powered system. The UVLO feature
oftheTPS2045andTPS2055alsoensurestheswitchwillbeoffafterthecardhasbeenremoved, andtheswitch
will be off during the next insertion. The UVLO feature guarantees a soft start with a controlled rise time for every
insertion of the card or module.
PC Board
TPS2045
Power
Supply
Block of
Circuitry
GND
OUT
OUT
OUT
OC
IN
2.7 V to 5.5 V
0.1 µF
1000 µF
Optimum
IN
EN
Overcurrent Response
Figure 33. Typical Hot-Plug Implementation
By placing the TPS2045 and TPS2055 between the V
input and the rest of the circuitry, the input power will
CC
reach these devices first after insertion. The typical rise time of the switch is approximately 2.5 ms, providng
aslowvoltagerampattheoutputofthedevice. Thisimplementaioncontrolssystemsurgecurrentsandprovides
a hot-plugging mechanism for any device.
20
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TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
MECHANICAL DATA
D (R-PDSO-G**)
PLASTIC SMALL-OUTLINE PACKAGE
14 PIN SHOWN
0.050 (1,27)
0.020 (0,51)
0.014 (0,35)
0.010 (0,25)
M
14
8
0.008 (0,20) NOM
0.244 (6,20)
0.228 (5,80)
0.157 (4,00)
0.150 (3,81)
Gage Plane
0.010 (0,25)
1
7
0°–8°
0.044 (1,12)
0.016 (0,40)
A
Seating Plane
0.004 (0,10)
0.010 (0,25)
0.004 (0,10)
0.069 (1,75) MAX
PINS **
8
14
16
DIM
0.197
(5,00)
0.344
(8,75)
0.394
(10,00)
A MAX
0.189
(4,80)
0.337
(8,55)
0.386
(9,80)
A MIN
4040047/D 10/96
NOTES: A. All linear dimensions are in inches (millimeters).
B. This drawing is subject to change without notice.
C. Body dimensions do not include mold flash or protrusion, not to exceed 0.006 (0,15).
D. Falls within JEDEC MS-012
21
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
MECHANICAL DATA
P (R-PDIP-T8)
PLASTIC DUAL-IN-LINE PACKAGE
0.400 (10,60)
0.355 (9,02)
8
5
0.260 (6,60)
0.240 (6,10)
1
4
0.070 (1,78) MAX
0.310 (7,87)
0.290 (7,37)
0.020 (0,51) MIN
0.200 (5,08) MAX
Seating Plane
0.125 (3,18) MIN
0.100 (2,54)
0°–15°
0.021 (0,53)
0.015 (0,38)
0.010 (0,25)
M
0.010 (0,25) NOM
4040082/B 03/95
NOTES: A. All linear dimensions are in inches (millimeters).
B. This drawing is subject to change without notice.
C. Falls within JEDEC MS-001
22
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
IMPORTANT NOTICE
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any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
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pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL
APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO
BE FULLY AT THE CUSTOMER’S RISK.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
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party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.
Copyright 1999, Texas Instruments Incorporated
相关型号：
TPS2045PE4
IC 0.44 A BUF OR INV BASED PRPHL DRVR, PDIP8, ROHS COMPLIANT, PLASTIC, DIP-8, Peripheral Driver
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