TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
features
D
135-mΩ -Maximum (5-V Input) High-Side
MOSFET Switch
D
250 mA Continuous Current
D
Short-Circuit and Thermal Protection With
Overcurrent Logic Output
D
Operating Range . . . 2.7-V to 5.5-V
D
Logic-Level Enable Input
D
2.5-ms Typical Rise Time
D
Undervoltage Lockout
D
10 µA Maximum Standby Supply Current
D
Bidirectional Switch
D
Available in 8-pin SOIC and PDIP Packages
D
Ambient Temperature Range, –40°C to 85°C
D
2-kV Human-Body-Model, 200-V
Machine-Model ESD Protection
typical applications
D
Notebook, Desktop and Palmtop PCs
D
Monitors, Keyboards, Scanners, and
Printers
D
Digital Cameras, Phones, and PBXs
D
Hot-Insertion Applications
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
controlled by a logic enable compatible with 5-V and 3-V logic. Gate drive is provided by an internal charge pump
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,
causing the junction temperature to rise, a thermal protection circuit shuts off the switch in overcurrent to prevent
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
TYPICAL SHORT-CIRCUIT
PACKAGED DEVICES
T
A
ENABLE
MAXIMUM CONTINUOUS
LOAD CURRENT
(A)
CURRENT LIMIT AT 25°C
(A)
SOIC
(D)
†
PDIP
(P)
–40°C to 85°C Active low 0.25 0.44 TPS2045D TPS2045P
–40°C to 85°C Active high 0.25 0.44 TPS2055D TPS2055P
†
The D package is available taped and reeled. Add an R suffix to device type (e.g., TPS2045DR)
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.
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.
1
2
3
4
8
7
6
5
GND
IN
IN
EN
OUT
OUT
OUT
OC
TPS2045
D OR P PACKAGE
(TOP VIEW)
1
2
3
4
8
7
6
5
GND
IN
IN
EN
OUT
OUT
OUT
OC
TPS2055
D OR P PACKAGE
(TOP VIEW)
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TPS2045 functional block diagram
OUT
OC
IN
EN
GND
Current
Limit
Driver
UVLO
Charge
Pump
CS
Thermal
Sense
Power Switch
†
†
Current Sense
Terminal Functions
TERMINAL
NO.
NAME
D OR P
I/O
DESCRIPTION
TPS2045 TPS2055
EN 4 – I Enable input. Logic low turns on power switch.
EN – 4 I Enable input. Logic high turns on power switch.
GND 1 1 I Ground
IN 2, 3 2, 3 I Input voltage
OC 5 5 O Over current. Logic output active low
OUT 6, 7, 8 6, 7, 8 O Power-switch output
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
detailed description
power switch
The power switch is an N-channel MOSFET with a maximum on-state resistance of 135 mΩ (V
I(IN)
= 5 V).
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. T o 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)
The logic enable disables the power switch and the bias for the charge pump, driver, and other circuitry to reduce
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.
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
†
Input voltage range, V
I(IN)
(see Note 1) –0.3 V to 6 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output voltage range, V
O(OUT)
(see Note 1) –0.3 V to V
I(IN)
+ 0.3 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input voltage range, V
I(EN)
or V
I(EN)
–0.3 V to 6 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous output current, I
O(OUT)
internally limited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous total power dissipation See Dissipation Rating Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating virtual junction temperature range, T
J
–40°C to 125°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
stg
–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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
PACKAGE
TA ≤ 25°C
POWER RATING
DERATING FACTOR
ABOVE TA = 25°C
TA = 70°C
POWER RATING
TA = 85°C
POWER RATING
D 725 mW 5.8 mW/°C 464 mW 377 mW
P 1175 mW 9.4 mW/°C 752 mW 611 mW
recommended operating conditions
TPS2045 TPS2055
MIN MAX MIN MAX
UNIT
Input voltage, V
I(IN)
2.7 5.5 2.7 5.5 V
Input voltage, V
I(EN
)
or V
I(EN)
0 5.5 0 5.5 V
Continuous output current, I
O(OUT)
0 250 0 250 mA
Operating virtual junction temperature, T
J
–40 125 –40 125 °C
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
electrical characteristics over recommended operating junction temperature range, V
I(IN)
= 5.5 V,
I
O
= rated current, V
I(EN)
= 0 V, V
I(EN)
= Hi (unless otherwise noted)
power switch
TPS2045 TPS2055
PARAMETER
TEST CONDITIONS
†
MIN TYP MAX MIN TYP MAX
UNIT
V
I(IN)
= 5 V,
IO = 0.25 A
TJ = 25°C,
80 95 80 95
Static drain-source on-state
resistance, 5-V operation
V
I(IN)
= 5 V,
IO = 0.25 A
TJ = 85°C,
90 120 90 120
V
I(IN)
= 5 V,
IO = 0.25 A
TJ = 125°C,
100 135 100 135
mΩ
r
DS(on)
V
I(IN)
= 3.3 V,
IO = 0.25 A
TJ = 25°C,
85 105 85 105
Static drain-source on-state
resistance, 3.3-V operation
V
I(IN)
= 3.3 V,
IO = 0.25 A
TJ = 85°C,
100 135 100 135
V
I(IN)
= 3.3 V,
IO = 0.25 A
TJ = 125°C,
115 150 115 150
p
V
I(IN)
= 5.5 V,
CL = 1 µF,
TJ = 25°C,
RL = 20 Ω
2.5 2.5
trRise time, output
V
I(IN)
= 2.7 V,
CL = 1 µF,
TJ = 25°C,
RL = 20 Ω
3 3
ms
p
V
I(IN)
= 5.5 V,
CL = 1 µF,
TJ = 25°C,
RL = 20 Ω
4.4 4.4
tfFall time, output
V
I(IN)
= 2.7 V,
CL = 1 µF,
TJ = 25°C,
RL = 20 Ω
2.5 2.5
ms
†
Pulse-testing techniques maintain junction temperature close to ambient temperature; thermal effects must be taken into account separately.
enable input EN or EN
TPS2045 TPS2055
PARAMETER
TEST CONDITIONS
MIN TYP MAX MIN TYP MAX
UNIT
V
IH
High-level input voltage 2.7 V ≤ V
I(IN)
≤ 5.5 V 2 2 V
p
4.5 V ≤ V
I(IN)
≤ 5.5 V 0.8 0.8 V
VILLow-level input voltage
2.7 V ≤ V
I(IN)
≤ 4.5 V 0.4 0.4
p
TPS2045 V
I(EN)
= 0 V or V
I(EN)
= V
I(IN)
–0.5 0.5
IIInput current
TPS2055 V
I(EN
)
= V
I(IN)
or V
I(EN)
= 0 V
–0.5 0.5
µ
A
t
on
Turnon time CL = 100 µF, RL = 20 Ω 20 20 ms
t
off
Turnoff time CL = 100 µF, RL = 20 Ω 40 40
current limit
TPS2045 TPS2055
PARAMETER
TEST CONDITIONS
†
MIN TYP MAX MIN TYP MAX
UNIT
I
OS
Short-circuit output current
V
I(IN)
= 5 V, OUT connected to GND,
Device enabled into short circuit
0.345 0.44 0.525 0.345 0.44 0.525 A
†
Pulse-testing techniques maintain junction temperature close to ambient temperature; thermal effects must be taken into account separately.
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
electrical characteristics over recommended operating junction temperature range, V
I(IN)
= 5.5 V,
I
O
= rated current, V
I(EN)
= 0 V, V
I(EN)
= Hi (unless otherwise noted) (continued)
supply current
TPS2045 TPS2055
PARAMETER
TEST CONDITIONS
MIN TYP MAX MIN TYP MAX
UNIT
pp
TJ = 25°C
0.015 1
Su ly
current,
No Load
V
I(EN)
= V
I(IN)
–40°C ≤ TJ ≤ 125°C
TPS2045
10
,
low-level
on OUT
TJ = 25°C
0.015 1
µ
A
output
V
I(EN)
= 0
V
–40°C ≤ TJ ≤ 125°C
TPS2055
10
pp
TJ = 25°C
80 100
Su ly
current,
No Load
V
I(EN)
= 0
V
–40°C ≤ TJ ≤ 125°C
TPS2045
100
,
high-level
on OUT
TJ = 25°C
80 100
µ
A
output
V
I(EN)
=
V
I(IN)
–40°C ≤ TJ ≤ 125°C
TPS2055
100
Leakage
OUT
V
I(EN)
= V
I(IN)
–40°C ≤ TJ ≤ 125°C TPS2045 100
g
current
connecte
d
to ground
V
I(EN)
= 0 V –40°C ≤ TJ ≤ 125°C TPS2055 100
µ
A
Reverse
IN = high
V
I(EN
)
= 0 V
°
TPS2045 0.3
leak
age
current
g
impedance
V
I(EN)
= Hi
T
J
=
25°C
TPS2055 0.3
µ
A
undervoltage lockout
TPS2045 TPS2055
PARAMETER
TEST CONDITIONS
MIN TYP MAX MIN TYP MAX
UNIT
Low-level input voltage 2 2.5 2 2.5 V
Hysteresis TJ = 25°C 100 100 mV
overcurrent OC
TPS2045 TPS2055
PARAMETER
TEST CONDITIONS
MIN TYP MAX MIN TYP MAX
UNIT
Sink current
†
VO = 5 V 10 10 mA
Output low voltage IO = 5 V, V
OL(OC)
0.5 0.5 V
Off-state current
†
VO = 5 V, VO = 3.3 V 1 1 µA
†
Specified by design, not production tested.
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
RL CL
OUT
t
r
t
f
90%
90%
10%
10%
50%
50%
90%
10%
V
O(OUT)
V
I(EN)
V
O(OUT)
VOLTAGE WA VEFORMS
TEST CIRCUIT
t
on
t
off
50%
50%
90%
10%
V
I(EN)
V
O(OUT)
t
on
t
off
Figure 1. Test Circuit and Voltage Waveforms
Figure 2. Turnon Delay and Rise Time
with 0.1-µF Load
Figure 3. Turnoff Delay and Fall Time
with 0.1-µF Load
V
O(OUT)
(2 V/div)
0123456
t – Time – ms
78910
V
I(IN)
= 5 V
TA = 25°C
CL = 0.1 µF
V
I(EN)
(5 V/div)
0 1000 2000 3000
t – Time – ms
4000 5000
V
I(IN)
= 5 V
TA = 25°C
CL = 0.1 µF
V
O(OUT)
(2 V/div)
V
I(EN)
(5 V/div)
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
8
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
Figure 4. Turnon Delay and Rise Time
with 1-µF Load
Figure 5. Turnoff Delay and Fall Time
with 1-µF Load
0123456
t – Time – ms
78910
V
O(OUT)
(2 V/div)
V
I(IN)
= 5 V
TA = 25°C
CL = 1 µF
RL = 20 Ω
0 2 4 6 8 10 12
t – Time – ms
14 16 18 20
V
I(IN)
= 5 V
TA = 25°C
CL = 1 µF
RL = 20 Ω
V
O(OUT)
(2 V/div)
V
I(EN)
(5 V/div)
V
I(EN)
(5 V/div)
Figure 6. TPS2045, Short-Circuit Current,
Device Enabled into Short
012 345 6
t – Time – ms
78910
I
O(OUT)
(0.2 A/div)
V
I(IN)
= 5 V
TA = 25°C
Figure 7. TPS2045, Threshold Trip Current
with Ramped Load on Enabled Device
01020 30405060
t – Time – ms
70 80 90 100
I
O(OUT)
(0.5 A/div)
V
I(IN)
= 5 V
TA = 25°C
V
O(OUT)
(2 V/div)
V
I(EN)
(5 V/div)
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
9
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
Figure 8. Inrush Current with 220-µF, 100-µF
and 47-µF Load Capacitance
Figure 9. Ramped Load on Enabled Device
100 µF
220 µF
47 µF
0 2 4 6 8 10 12
t – Time – ms
14 16 18 20
V
I(IN)
= 5 V
TA = 25°C
RL = 20 Ω
I
O(OUT)
(0.2 A/div)
V
I(IN)
= 5 V
TA = 25°C
0 20 40 60 80 100 120
t – Time – ms
140 160 180 200
V
O(OC)
(5 V/div)
I
O(OUT)
(0.5 A/div)
V
I(EN)
(5 V/div)
Figure 10. 4-Ω Load Connected
to Enabled Device
I
O(OUT)
(0.5 A/div)
V
I(IN)
= 5 V
TA = 25°C
0 200 400 600 800 1000
t – Time – µs
Figure 11. 1-Ω Load Connected
to Enabled Device
V
I(IN)
= 5 V
TA = 25°C
0 200 400 600 800 1000
t – Time – µs
I
O(OUT)
(0.5 A/div)
V
O(OC)
(5 V/div)
V
O(OC)
(5 V/div)
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
10
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TYPICAL CHARACTERISTICS
Figure 12
4.5
4
3.5
3
2.5 3 3.5 4 4.5
Turnon Delay – ms
5
5.5
TURNON DELAY
vs
INPUT VOLTAGE
6
5 5.5 6
VI – Input Voltage – V
CL = 1 µF
RL = 20 Ω
TA = 25°C
Figure 13
15
13
9
7
2.5 3 3.5 4 4.5
Turnoff Delay – ms
TURNOFF DELAY
vs
INPUT VOLTAGE
5 5.5 6
11
VI – Input Voltage – V
CL = 1 µF
RL = 20 Ω
TA = 25°C
Figure 14
2.5
2.4
2.3
0 0.05 0.1 0.15 0.2 0.25
– Rise Time – ms
2.6
RISE TIME
vs
LOAD CURRENT
2.7
0.3 0.35 0.4
t
r
IL – Load Current – A
VI
(IN)
= 5 V
TA = 25°C
Figure 15
2.75
2.7
2.65
0 0.05 0.1 0.15 0.2 0.25
– Fall Time – ms
2.8
FALL TIME
vs
LOAD CURRENT
2.85
0.3 0.35 0.4
t
f
IL – Load Current – A
VI
(IN)
= 5 V
TA = 25°C
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
11
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TYPICAL CHARACTERISTICS
Figure 16
140
120
100
–50 –25 0 25 50
– Supply Current, Output Enabled –
160
180
SUPPLY CURRENT, OUTPUT ENABLED
vs
JUNCTION TEMPERATURE
200
75 100 125 150
I
I(IN)
Aµ
TJ – Junction Temperature – °C
V
I(IN)
= 5.5 V
V
I(IN)
= 5 V
V
I(IN)
= 4 V
V
I(IN)
= 3.3 V
V
I(IN)
= 2.7 V
Figure 17
1000
600
200
–200
–50 –25 0 25 50 75
1400
1800
SUPPLY CURRENT, OUTPUT DISABLED
vs
JUNCTION TEMPERATURE
2000
100 125 150
1600
1200
800
400
0
– Supply Current, Output Disabled – nA
I
I(IN)
TJ – Junction Temperature – °C
V
I(IN)
= 5.5 V
V
I(IN)
= 5 V
V
I(IN)
= 4 V
V
I(IN)
= 2.7 V
Figure 18
140
120
100
2.5 3 3.5 4
4.5
– Supply Current, Output Enabled –
160
180
SUPPLY CURRENT, OUTPUT ENABLED
vs
INPUT VOLTAGE
200
5 5.5 6
I
I(IN)
Aµ
VI – Input Voltage – V
TJ = –40°C
TJ = 125°C
TJ = 85°C
TJ = 25°C
TJ = 0°C
Figure 19
800
400
0
–400
2.5 3 3.5 4 4.5
1200
1600
SUPPLY CURRENT, OUTPUT DISABLED
vs
INPUT VOLTAGE
2000
5 5.5 6
– Supply Current, Output Disabled – nA
I
I(IN)
VI – Input Voltage – V
TJ = –40°C
TJ = 125°C
TJ = 85°C
TJ = 25°C
TJ = 0°C
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
12
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TYPICAL CHARACTERISTICS
Figure 20
100
75
50
–50 –25 0 25 50 75
– Static Drain-Source On-State Resistance – m
125
150
STATIC DRAIN-SOURCE ON-STATE RESISTANCE
vs
JUNCTION TEMPERATURE
175
100 125 150
Ω
r
DS(on)
TJ – Junction Temperature –°C
V
I(IN)
= 5 V
V
I(IN)
= 4.5 V
V
I(IN)
= 3.3 V
V
I(IN)
= 2.7 V
IO = 0.25 A
Figure 21
100
75
50
2.5 3 3.5 4 4.5
125
150
STATIC DRAIN-SOURCE ON-STATE RESISTANCE
vs
INPUT VOLTAGE
175
5 5.5 6
– Static Drain-Source On-State Resistance – m
Ω
r
DS(on)
VI – Input Voltage – V
TJ = –40°C
TJ = 125°C
TJ = 85°C
TJ = 25°C
TJ = 0°C
IO = 0.25 A
Figure 22
V
I(IN)
= 5 V
V
I(IN)
= 2.7 V
V
I(IN)
= 4.5 V
V
I(IN)
= 3.3 V
25
15
0
0.1 0.14 0.18
– Input-To-Output Voltage – mV
40
INPUT-TO-OUTPUT VOLTAGE
vs
LOAD CURRENT
45
0.22 0.3
V
I(IN)
–
V
O(OUT)
IL – Load Current – A
35
30
20
10
5
0.26
TA = 25°C
Figure 23
TJ = –40°C
TJ = 25°C
TJ = 125°C
390
350
2.5 3 3.5 4
– Short-circuit Output Current – mA
450
SHORT-CURCUIT OUTPUT CURRENT
vs
INPUT VOLTAGE
490
4.5 5 5.5
I
OS
VI – Input Voltage – V
470
430
410
370
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
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POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TYPICAL CHARACTERISTICS
Figure 24
0.69
0.67
0.65
2.5 3 3.5 4
Threshold Trip Current – A
0.71
THRESHOLD TRIP CURRENT
vs
INPUT VOLTAGE
0.73
4.5 5 65.5
VI – Input Voltage – V
TA = 25°C
Load Ramp = 1 A/10 ms
Figure 25
420
405
–50 –25 0 25 50
435
SHORTCIRCUIT OUTPUT CURRENT
vs
JUNCTION TEMPERATURE
450
75 100 125
TJ – Junction Temperature – °C
– Short-circuit Output Current – mA
I
OS
V
I(IN)
= 5 V
V
I(IN)
= 4 V
V
I(IN)
= 2.7 V
445
440
430
425
415
410
Figure 26
2.2
2.1
2
–50 –25 0 25 50 75
UVLO – Undervoltage Lockout – V
2.3
2.4
UNDERVOLTAGE LOCKOUT
vs
JUNCTION TEMPERATURE
2.5
100 125 150
TJ – Junction Temperature – °C
Start Threshold
Stop Threshold
Figure 27
250
100
0
02 4 6
Current Limit Response –
350
Peak Current – A
CURRENT-LIMIT RESPONSE
vs
PEAK CURRENT
500
810
sµ
V
I(IN)
= 5 V
TA = 25°C
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
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POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TYPICAL CHARACTERISTICS
Figure 28
7
5.5
4
024 6
Overcurrent OC Time –
8.5
Peak Current – A
OVERCURRENT (OC) RESPONSE TIME
vs
PEAK CURRENT
10
810
sµ
V
I(IN)
= 5 V
TA = 25°C
APPLICATION INFORMATION
IN
OC
EN
GND
0.1 µF
2,3
5
4
6,7,8
0.1 µF 22 µF
Load
1
OUT
TPS2045
Power Supply
2.7 V to 5.5 V
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.
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
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POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
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
I(IN)
has been applied (see Figure 6). The TPS2045 and TPS2055 sense the short
and immediately switch into a constant-current output.
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.
Connecting a heavy capacitive load to an enabled device can cause momentary false overcurrent reporting from
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.
GND
IN
IN
EN
OUT
OC
OUT
OUT
TPS2045
GND
IN
IN
EN
OUT
OC
OUT
OUT
TPS2045
R
pullup
V+
R
filter
R
pullup
C
filter
To USB
Controller
V+
Figure 30. Typical Circuit for OC Pin and RC Filter for Damping Inrush OC Responses
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
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POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
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
DS(on)
at
the input voltage and operating temperature. As an initial estimate, use the highest operating ambient
temperature of interest and read r
DS(on)
from Figure 21. Next, calculate the power dissipation using:
P
D
+
r
DS(on
)
I
2
Finally, calculate the junction temperature:
T
J
+
P
D
R
q
JA
)
T
A
Where:
TA = Ambient Temperature °C
R
θJA
= 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
extended periods of time. The faults force the TPS2045 and TPS2055 into constant current mode, which causes
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)
An undervoltage lockout ensures that the power switch is in the off state at power up. Whenever the input voltage
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.
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
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POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
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:
D
Hosts/self-powered hubs (SPH)
D
Bus-powered hubs (BPH)
D
Low-power, bus-powered functions
D
High-power, bus-powered functions
D
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).
IN
OC
EN
GND
0.1 µF
2,3
5
4
6, 7, 8
0.1 µF 10 µF
GND
1
OUT
TPS2045
Power Supply
D+
D–
V
BUS
USB
Control
3.3 V
10 µF
Internal
Function
Figure 31. High-Power Bus-Powered Function
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
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POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
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.
D
Bus-Powered Hubs must:
– Enable/disable power to downstream ports
– Power up at <100 mA
– Limit inrush current (<44 Ω and 10 µF)
D
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).
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
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POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
Figure 32. Bus-Powered Hub Implementation
†
USB rev 1.1 requires 120 µF per hub.
DP1
DM1
DP2
DM2
DP3
DM3
DP4
PWRON1
OVRCUR1
PWRON2
OVRCUR2
PWRON3
OVRCUR3
PWRON4
OVRCUR4
DM4
DP0
DM0
V
CC
XTAL1
XTAL2
OCSOFF
SN75240
D +
D –
5 V
GND
D +
D –
5 V
D +
D –
5 V
D +
D –
5 V
48-MHz
Crystal
Downstream
Ports
TUSB2040
Hub Controller
Tuning
Circuit
ABC
D
33 µF
†
SN75240
ABC
D
GND
GND
GND
33 µF
†
33 µF
†
33 µF
†
D +
D –
Upstream
Port
SN75240
A
B
5 V
GND
C
D
1 µF
GND
Ferrite Beads
Ferrite Beads
Ferrite Beads
Ferrite Beads
BUSPWR
GANGED
IN
GND
3.3 V
4.7 µF
0.1 µF
4.7 µF
GND
EN
OC
IN
TPS2045
OUT
EN
OC
IN
TPS2045
OUT
EN
OC
IN
TPS2045
OUT
EN
OC
IN
TPS2045
OUT
0.1 µF
0.1 µF
0.1 µF
0.1 µF
TPS76333
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
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POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
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
of the TPS2045 and TPS2055 also ensures the switch will be off after the card has been removed, and the switch
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.
Power
Supply
Block of
Circuitry
TPS2045
GND
IN
IN
EN
OUT
OUT
OUT
OC
0.1 µF
1000 µF
Optimum
2.7 V to 5.5 V
PC Board
Overcurrent Response
Figure 33. Typical Hot-Plug Implementation
By placing the TPS2045 and TPS2055 between the VCC input and the rest of the circuitry , the input power will
reach these devices first after insertion. The typical rise time of the switch is approximately 2.5 ms, providng
a slow voltage ramp at the output of the device. This implementaion controls system surge currents and provides
a hot-plugging mechanism for any device.
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
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POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
MECHANICAL DATA
D (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE
14 PIN SHOWN
4040047/D 10/96
0.228 (5,80)
0.244 (6,20)
0.069 (1,75) MAX
0.010 (0,25)
0.004 (0,10)
1
14
0.014 (0,35)
0.020 (0,51)
A
0.157 (4,00)
0.150 (3,81)
7
8
0.044 (1,12)
0.016 (0,40)
Seating Plane
0.010 (0,25)
PINS **
0.008 (0,20) NOM
A MIN
A MAX
DIM
Gage Plane
0.189
(4,80)
(5,00)
0.197
8
(8,55)
(8,75)
0.337
14
0.344
(9,80)
16
0.394
(10,00)
0.386
0.004 (0,10)
M
0.010 (0,25)
0.050 (1,27)
0°–8°
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
TPS2045, TPS2055
CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES
SLVS182 – APRIL 1999
22
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
MECHANICAL DATA
P (R-PDIP-T8) PLASTIC DUAL-IN-LINE PACKAGE
4040082/B 03/95
0.310 (7,87)
0.290 (7,37)
0.010 (0,25) NOM
0.400 (10,60)
0.355 (9,02)
58
41
0.020 (0,51) MIN
0.070 (1,78) MAX
0.240 (6,10)
0.260 (6,60)
0.200 (5,08) MAX
0.125 (3,18) MIN
0.015 (0,38)
0.021 (0,53)
Seating Plane
M
0.010 (0,25)
0.100 (2,54)
0°–15°
NOTES: A. All linear dimensions are in inches (millimeters).
B. This drawing is subject to change without notice.
C. Falls within JEDEC MS-001
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any product or service without notice, and advise customers to obtain the latest version of relevant information
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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
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CERT AIN APPLICATIONS USING SEMICONDUCT OR 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
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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
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Copyright 1999, Texas Instruments Incorporated
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