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TPS22918
SLVSD76C – FEBRUARY 2016 – REVISED JULY 2017
TPS22918 5.5-V, 2-A, 52-mΩ On-Resistance Load Switch
1 Features
3 Description
•
•
The TPS22918 is a single-channel load switch with
configurable rise time and configurable quick output
discharge. The device contains an N-channel
MOSFET that can operate over an input voltage
range of 1 V to 5.5 V and can support a maximum
continuous current of 2 A. The switch is controlled by
an on and off input, which is capable of interfacing
directly with low-voltage control signals.
1
•
•
•
•
•
•
•
•
•
Integrated Single Channel Load Switch
Ambient Operating Temperature: –40°C to
+105°C
Input Voltage Range: 1 V to 5.5 V
On-Resistance (RON)
– RON = 52 mΩ (typical) at VIN = 5 V
– RON = 53 mΩ (typical) at VIN = 3.3 V
2-A Maximum Continuous Switch Current
Low Quiescent Current
– 8.3 µA (typical) at VIN = 3.3 V
Low-Control Input-Threshold Enables Use of 1 V
or Higher GPIO
Adjustable Quick-Output Discharge (QOD)
Configurable Rise Time With CT Pin
Small SOT23-6 Package (DBV)
– 2.90-mm × 2.80-mm, 0.95-mm Pitch,
1.45 mm Height (with leads)
ESD Performance Tested per JESD 22
– ±2-kV HBM and ±1-kV CDM
The configurable rise time of the device greatly
reduces inrush current caused by large bulk load
capacitances, thereby reducing or eliminating power
supply droop. The TPS22918 features a configurable
quick output discharge (QOD) pin, which controls the
fall time of the device to allow design flexibility for
power down and sequencing.
The TPS22918 is available in a small, leaded SOT-23
package (DBV) which allows visual inspection of
solder joints. The device is characterized for
operation over the free-air temperature range of
–40°C to +105°C.
Device Information
PART NUMBER
TPS22918
2 Applications
•
•
•
•
100
VOUT
CIN
RL
CL
ON
ON
OFF
TPS22918
CT
On-Resistance (m:)
QOD
-40qC
25qC
85qC
105qC
90
REXT
GND
2.90 mm × 1.60 mm
On-Resistance vs Input Voltage
Typical Values
Simplified Schematic
VIN
SOT-23 (6)
BODY SIZE (NOM)
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Industrial Systems
Set Top Box
Blood Glucose Meters
Electronic Point of Sale
Power
Supply
PACKAGE
(1)
80
70
60
50
40
30
1
1.5
2
2.5
3
3.5
4
Input Voltage (V)
4.5
5
5.5
D001
IOUT = –200 mA
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.
TPS22918
SLVSD76C – FEBRUARY 2016 – REVISED JULY 2017
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
4
4
4
4
5
6
7
9
Absolute Maximum Ratings ......................................
ESD Ratings ............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Switching Characteristics ..........................................
Typical DC Characteristics........................................
Typical AC Characteristics........................................
Parameter Measurement Information ................ 11
Detailed Description ............................................ 12
8.1 Overview ................................................................. 12
8.2 Functional Block Diagram ....................................... 12
8.3 Feature Description................................................. 13
8.4 Device Functional Modes........................................ 15
9
Application and Implementation ........................ 16
9.1 Application Information............................................ 16
9.2 Typical Application ................................................. 16
10 Power Supply Recommendations ..................... 20
11 Layout................................................................... 20
11.1 Layout Guidelines ................................................. 20
11.2 Layout Example .................................................... 21
11.3 Thermal Considerations ........................................ 21
12 Device and Documentation Support ................. 22
12.1
12.2
12.3
12.4
12.5
12.6
Device Support......................................................
Documentation Support ........................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
22
22
22
22
22
22
13 Mechanical, Packaging, and Orderable
Information ........................................................... 22
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (March 2016) to Revision B
•
Updated the constant value in Equation 3 in Adjustable Rise Time (CT) section................................................................ 14
Changes from Revision B (June 2016) to Revision C
•
2
Page
Updated the Applications Section changed µF to pF in Figure 30, Figure 31, and Section 9.2.2.5 ...................................... 1
Changes from Original (February 2016) to Revision A
•
Page
Page
Changed device status from Product Preview to Production Data ........................................................................................ 1
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SLVSD76C – FEBRUARY 2016 – REVISED JULY 2017
5 Pin Configuration and Functions
DBV Package
6-Pin SOT-23
Top View
VIN
1
6
VOUT
GND
2
5
QOD
ON
3
4
CT
Pin Functions
PIN
NO.
NAME
I/O
DESCRIPTION
Switch input. Place ceramic bypass capacitor(s) between this pin and GND. See the
Detailed Description section for more information.
1
VIN
I
2
GND
—
3
ON
I
Active high switch control input. Do not leave floating.
4
CT
O
Switch slew rate control. Can be left floating. See the Feature Description section for
more information.
Device ground.
5
QOD
O
Quick Output Discharge pin. This functionality can be enabled in one of three ways.
•
Placing an external resistor between VOUT and QOD
•
Tying QOD directly to VOUT and using the internal resistor value (RPD)
•
Disabling QOD by leaving pin floating
See the Quick Output Discharge (QOD) section for more information.
6
VOUT
O
Switch output.
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6 Specifications
6.1 Absolute Maximum Ratings
Over operating free-air temperature range (unless otherwise noted)
(1) (2)
MIN
MAX
UNIT
VIN
Input voltage
–0.3
6
V
VOUT
Output voltage
–0.3
6
V
VON
ON voltage
–0.3
6
V
IMAX
Maximum continuous switch current, ambient temperature = 70°C
2
A
IPLS
Maximum pulsed switch current, pulse < 300 µs, 2% duty cycle
2.5
A
TJ
Maximum junction temperature
125
°C
Tstg
Storage temperature
150
°C
(1)
(2)
–65
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.
All voltage values are with respect to network ground terminal.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
Electrostatic discharge
(1)
UNIT
±2000
Charged-device model (CDM), per JEDEC specification JESD22-C101
(2)
V
±1000
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.
6.3 Recommended Operating Conditions
Over operating free-air temperature range (unless otherwise noted)
MIN
MAX
VIN
Input voltage
0
5.5
V
VON
ON voltage
0
5.5
V
VOUT
Output voltage
VIN
V
VIH,
ON
High-level input voltage, ON
VIN = 1 V to 5.5 V
1
5.5
V
VIL,
ON
Low-level input voltage, ON
VIN = 1 V to 5.5 V
0
0.5
V
105
°C
TA
Operating free-air temperature (1)
–40
CIN
Input Capacitor
1
(1)
(2)
UNIT
(2)
µF
In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may
have to be derated. Maximum ambient temperature [TA(max)] is dependent on the maximum operating junction temperature [TJ(MAX)], the
maximum power dissipation of the device in the application [PD(MAX)], and the junction-to-ambient thermal resistance of the part/package
in the application (θJA), as given by the following equation: TA(MAX) = TJ(MAX) – (θJA × PD(MAX)).
Refer to Application and Implementation section
6.4 Thermal Information
TPS22918
THERMAL METRIC
(1)
DBV (SOT-23)
UNIT
6 PINS
RθJA
Junction-to-ambient thermal resistance
183.2
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
151.6
°C/W
RθJB
Junction-to-board thermal resistance
34.1
°C/W
ψJT
Junction-to-top characterization parameter
37.2
°C/W
ψJB
Junction-to-board characterization parameter
33.6
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
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6.5 Electrical Characteristics
Unless otherwise noted, the specification in the following table applies over the full ambient operating temperature
–40°C ≤ TA ≤ +105°C. Typical values are for TA = 25°C.
PARAMETER
IQ, VIN
ISD, VIN
Quiescent current VON = 5 V, IOUT = 0 A
Shutdown current VON = 0 V, VOUT = 0 V
ON pin input
leakage current
ION
TEST CONDITIONS
TYP
MAX
VIN = 5.5 V
9.2
16
VIN = 5 V
8.7
16
VIN = 3.3 V
8.3
15
10.2
17
VIN = 1.2 V
9.3
16
VIN = 1 V
8.9
15
VIN = 5.5 V
0.5
5
VIN = 5 V
0.5
4.5
0.5
3.5
0.5
2.5
VIN = 1.2 V
0.4
2
VIN = 1 V
0.4
2
VIN = 1.8 V
VIN = 3.3 V
VIN = 1.8 V
VIN = 5.5 V, IOUT = 0 A
TA
MIN
–40°C to +105°C
–40°C to +105°C
–40°C to +105°C
0.1
25°C
VIN = 5.5 V, IOUT = –200 mA
51
71
–40°C to +105°C
78
52
71
–40°C to +105°C
79
VIN = 4.2 V, IOUT = –200 mA
52
71
–40°C to +105°C
79
RON
53
–40°C to +85°C
53
–40°C to +85°C
55
–40°C to +85°C
64
VIN = 5.0 V, VON = 0 V
RPD
Output pull down
resistance (1)
VIN = 3.3 V, VON = 0 V
VIN = 1.8 V, VON = 0 V
(1)
77
–40°C to +85°C
88
–40°C to +105°C
104
25°C
ON pin hysteresis VIN = 1 V to 5.5 V
mΩ
88
25°C
VHYS
mΩ
65
79
–40°C to +105°C
VIN = 1.0 V, IOUT = –200 mA
mΩ
80
25°C
VIN = 1.2 V, IOUT = –200 mA
mΩ
61
75
–40°C to +105°C
VIN = 1.8 V, IOUT = –200 mA
mΩ
80
25°C
VIN = 2.5 V, IOUT = –200 mA
mΩ
59
71
–40°C to +105°C
On-Resistance
µA
59
–40°C to +85°C
25°C
VIN = 3.3 V, IOUT = –200 mA
µA
59
–40°C to +85°C
25°C
µA
59
–40°C to +85°C
25°C
VIN = 5.0 V, IOUT = –200 mA
UNIT
71
85
–40°C to +85°C
100
–40°C to +105°C
116
–40°C to +105°C
107
25°C
mΩ
mΩ
mV
24
–40°C to +105°C
30
25°C
25
–40°C to +105°C
35
25°C
Ω
45
–40°C to +105°C
60
Output pull down resistance varies with input voltage. Please see Figure 7 for more information.
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6.6 Switching Characteristics
Refer to the timing test circuit in Figure 21 (unless otherwise noted) for references to external components used for the test
condition in the switching characteristics table. Switching characteristics shown below are only valid for the power-up
sequence where VIN is already in steady state condition before the ON pin is asserted high. VON = 5 V, TA = 25 °C, QOD =
Open.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VIN = 5 V
tON
Turn-on time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
tOFF
Turn-off time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
1950
2
tR
VOUT rise time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
2540
tF
VOUT fall time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
2
tD
Delay time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
690
tON
Turn-on time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
1430
tOFF
Turn-off time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
2
tR
VOUT rise time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
1680
tF
VOUT fall time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
2
tD
Delay time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
590
tON
Turn-on time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
965
tOFF
Turn-off time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
2
tR
VOUT rise time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
960
tF
VOUT fall time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
2
tD
Delay time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
480
tON
Turn-on time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
725
tOFF
Turn-off time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
3
tR
VOUT rise time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
560
tF
VOUT fall time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
2
tD
Delay time
RL = 10 Ω, CIN = 1 µF, CL = 0.1 µF, CT = 1000 pF
430
µs
VIN = 3.3 V
µs
VIN = 1.8 V
µs
VIN = 1 V
6
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6.7 Typical DC Characteristics
3
11
-40qC
25qC
85qC
105qC
10.5
2.5
Shutdown Current (PA)
Quiescent Current (PA)
10
9.5
9
8.5
8
7.5
-40qC
25qC
85qC
105qC
7
6.5
2
1.5
1
0.5
6
0
1
1.5
2
2.5
3
3.5
4
Input Voltage (V)
VON = 5 V
4.5
5
5.5
1
IOUT = 0 A
90
90
80
70
60
50
40
20
-40
VIN = 1.8 V
VIN = 2.5 V
VIN = 3.3 V
VIN = 4.2 V
VIN = 5 V
VIN = 5.5 V
4.5
5
5.5
D003
IOUT = 0 A
-40qC
25qC
85qC
105qC
80
70
60
50
40
0
20
40
Temperature (qC)
60
80
100
1
1.5
2
2.5
D004
IOUT = –200 mA
VON = 5 V
Figure 3. On-Resistance vs Temperature
3
3.5
4
Input Voltage (V)
4.5
5
5.5
D001
IOUT = –200 mA
Figure 4. On-Resistance vs Input Voltage
100
140
90
120
Hysteresis Voltage (mV)
80
On-Resistance (m:)
3
3.5
4
Input Voltage (V)
30
-20
VON = 5 V
70
60
50
40
30
20
VIN= 1 V
VIN = 1.2 V
VIN = 1.5 V
10
0
0.2
2.5
Figure 2. Shutdown Current vs Input Voltage
100
On-Resistance (m:)
On-Resistance (m:)
Figure 1. Quiescent Current vs Input Voltage
30
2
VON = 0 V
100
VIN= 1 V
VIN = 1.05 V
VIN = 1.2 V
1.5
D002
VIN = 1.8 V
VIN = 2.5 V
VIN = 3.3 V
VIN = 4.2 V
VIN = 5 V
VIN = 5.5 V
100
80
60
40
-40qC
25qC
85qC
105qC
20
0
0.4
VON = 5 V
0.6
0.8
1
1.2
1.4
Output Current (A)
1.6
1.8
2
1
1.5
D005
TA = 25°C
2
2.5
3
3.5
4
Input Voltage (V)
4.5
5
5.5
D008
IOUT = 0 A
Figure 5. On-Resistance vs Output Current
Figure 6. Hysteresis Voltage vs Input Voltage
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Typical DC Characteristics (continued)
Output Pull-Down Resistance (:)
275
-40qC
25qC
85qC
105qC
250
225
200
175
150
125
100
75
50
25
0
1
VIN = VOUT
1.5
2
2.5
3
3.5
4
Input Voltage (V)
4.5
5
5.5
D009
VON = 0 V
Figure 7. Output Pull-Down Resistance vs Input Voltage
8
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3000
800
2500
700
Delay Time (Ps)
Rise Time (Ps)
6.8 Typical AC Characteristics
2000
1500
-40qC
25qC
85qC
105qC
1000
600
500
-40qC
25qC
85qC
105qC
400
500
300
1
1.5
2
2.5
3
3.5
4
Input Voltage (V)
CIN = 1 µF
CT = 1000 pF
4.5
5
5.5
1
RL = 10 Ω
CL = 0.1 µF
2
2.5
CIN = 1 µF
Figure 8. Rise Time vs Input Voltage
3
3.5
4
Input Voltage (V)
4.5
5
5.5
D011
RL = 10 Ω
CL = 0.1 µF
Figure 9. Delay Time vs Input Voltage
5
5
-40qC
25qC
85qC
105qC
-40qC
25qC
85qC
105qC
4
Turnoff Time (Ps)
4
Fall Time (Ps)
1.5
D010
3
2
3
2
1
1
0
0
1
1.5
CIN = 1 µF
2
2.5
3
3.5
4
Input Voltage (V)
RL = 10 Ω
4.5
5
5.5
1
1.5
D012
CL = 0.1 µF
QOD = Open
CIN = 1 µF
Figure 10. Fall Time vs Input Voltage
2
2.5
3
3.5
4
Input Voltage (V)
RL = 10 Ω
4.5
5
5.5
D013
CL = 0.1 µF
Figure 11. Turnoff Time vs Input Voltage
2150
Turnon Time (Ps)
1850
1550
1250
-40qC
25qC
85qC
105qC
950
650
1
1.5
CIN = 1 µF
CT = 1000 pF
2
2.5
3
3.5
4
Input Voltage (V)
4.5
RL = 10 Ω
5
5.5
D014
CL = 0.1 µF
VIN = 5 V
RL = 10 Ω
Figure 12. Turnon Time vs Input Voltage
CIN = 1 µF
CT = 1000 pF
CL = 0.1 µF
Figure 13. Rise Time (tR) at VIN = 5 V
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Typical AC Characteristics (continued)
VIN = 5 V
RL = 10 Ω
CIN = 1 µF
QOD = Open
CL = 0.1 µF
VIN = 3.3 V
RL = 10 Ω
Figure 14. Fall Time (tF) at VIN = 5 V
VIN = 3.3 V
RL = 10 Ω
CIN = 1 µF
QOD = Open
CIN = 1 µF
QOD = Open
CL = 0.1 µF
VIN = 1.8 V
RL = 10 Ω
CL = 0.1 µF
CIN = 1 µF
CT = 1000 pF
CL = 0.1 µF
Figure 17. Rise Time (tR) at VIN = 1.8 V
VIN = 1.0 V
RL = 10 Ω
Figure 18. Fall Time (tF) at VIN = 1.8 V
10
CL = 0.1 µF
Figure 15. Rise Time (tR) at VIN = 3.3 V
Figure 16. Fall Time (tF) at VIN = 3.3 V
VIN = 1.8 V
RL = 10 Ω
CIN = 1 µF
CT = 1000 pF
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CIN = 1 µF
CT = 1000 pF
CL = 0.1 µF
Figure 19. Rise Time (tR) at VIN = 1 V
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Typical AC Characteristics (continued)
VIN = 1.0 V
RL = 10 Ω
CIN = 1 µF
QOD = Open
CL = 0.1 µF
Figure 20. Fall Time (tF) at VIN = 1 V
7 Parameter Measurement Information
(1)
Rise and fall times of the control signal are 100 ns
(2)
Turn-off times and fall times are dependent on the time constant at the load. For TPS22918, the internal pull-down
resistance RPD is enabled when the switch is disabled. The time constant is (RQOD || RL) × CL.
Figure 21. Test Circuit
VON
50%
50%
tOFF
tON
VOUT
50%
50%
tF
tR
90%
VOUT
10%
10%
90%
10%
tD
Figure 22. Timing Waveforms
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8 Detailed Description
8.1 Overview
The TPS22918 is a 5.5-V, 2-A load switch in a 6-pin SOT-23 package. To reduce voltage drop for low voltage
and high current rails, the device implements a low resistance N-channel MOSFET which reduces the drop out
voltage across the device.
The device has a configurable slew rate which helps reduce or eliminate power supply droop because of large
inrush currents. Furthermore, the device features a QOD pin, which allows the configuration of the discharge rate
of VOUT once the switch is disabled. During shutdown, the device has very low leakage currents, thereby
reducing unnecessary leakages for downstream modules during standby. Integrated control logic, driver, charge
pump, and output discharge FET eliminates the need for any external components which reduces solution size
and bill of materials (BOM) count.
8.2 Functional Block Diagram
VIN
Charge Pump
ON
Control
Logic
CT
VOUT
QOD
GND
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8.3 Feature Description
8.3.1 On and Off Control
The ON pin controls the state of the switch. ON is active high and has a low threshold, making it capable of
interfacing with low-voltage signals. The ON pin is compatible with standard GPIO logic threshold. It can be used
with any microcontroller with 1 V or higher GPIO voltage. This pin cannot be left floating and must be driven
either high or low for proper functionality.
8.3.2 Quick Output Discharge (QOD)
The TPS22918 includes a QOD feature. The QOD pin can be configured in one of three ways:
• QOD pin shorted to VOUT pin. Using this method, the discharge rate after the switch becomes disabled is
controlled with the value of the internal resistance RPD. The value of this resistance is listed in the Electrical
Characteristics table.
• QOD pin connected to VOUT pin using an external resistor REXT. After the switch becomes disabled, the
discharge rate is controlled by the value of the total resistance of the QOD. To adjust the total QOD
resistance, Equation 1 can be used:
RQOD = RPD + REXT
Where:
•
•
•
•
RQOD = Total output discharge resistance
RPD = Internal pulldown resistance
REXT = External resistance placed between the VOUT and QOD pin.
(1)
QOD pin is unused and left floating. Using this method, there will be no quick output discharge functionality,
and the output will remain floating after the switch is disabled.
The fall times of the device depend on many factors including the total resistance of the QOD, VIN, and the
output capacitance. When QOD is shorted to VOUT, the fall time will change over VIN as the internal RPD varies
over VIN. To calculate the approximate fall time of VOUT for a given RQOD, use Equation 2 and Table 1.
VCAP = VIN × e-t/τ
Where:
•
•
•
VCAP = Voltage across the capacitor (V)
t = Time since power supply removal (s)
τ = Time constant equal to RQOD × CL
(2)
The fall times' dependency on VIN becomes minimal as the QOD value increases with additional external
resistance. See Table 1 for QOD fall times.
Table 1. QOD Fall Times
(1)
FALL TIME (μs) 90% - 10%, CIN = 1 μF, IOUT = 0 A , VON = 0 V
VIN (V)
(1)
TA = 25°C
TA = 85°C
CL = 1 μF
CL = 10 μF
CL = 100 μF
CL = 1 μF
CL = 10 μF
CL = 100 μF
5.5
42
190
1880
40
210
2150
5
43
200
1905
45
220
2200
3.3
47
230
2150
50
260
2515
2.5
58
300
2790
60
345
3290
1.8
75
430
4165
80
490
4950
1.2
135
955
9910
135
1035
10980
1
230
1830
19625
210
1800
19270
TYPICAL VALUES WITH QOD SHORTED TO VOUT
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8.3.2.1 QOD when System Power is Removed
The adjustable QOD can be used to control the power down sequencing of a system even when the system
power supply is removed. When the power is removed, the input capacitor discharges at VIN. Past a certain VIN
level, the strength of the RPD will be reduced. If there is still remaining charge on the output capacitor, this will
result in longer fall times. For further information regarding this condition, see the Shutdown Sequencing During
Unexpected System Power Loss section.
8.3.2.2
Internal QOD Considerations
Special considerations must be taken when using the internal RPD by shorting the QOD pin to the VOUT pin. The
internal RPD is a pulldown resistance designed to quickly discharge a load after the switch has been disabled.
Care must be used to ensure that excessive current does not flow through RPD during discharge so that the
maximum TJ of 125°C is not exceeded. When using only the internal RPD to discharge a load, the total capacitive
load must not exceed 200 µF. Otherwise, an external resistor, REXT, must be used to ensure the amount of
current flowing through RPD is properly limited and the maximum TJ is not exceeded. To ensure the device is not
damaged, the remaining charge from CL must decay naturally through the internal QOD resistance and should
not be driven.
8.3.3 Adjustable Rise Time (CT)
A capacitor to GND on the CT pin sets the slew rate of VOUT. The CT capacitor will charge up until shortly after
the switch is turned on and VOUT becomes stable. Once VOUT become stable, the capactior will discharge to
ground. An approximate formula for the relationship between CT and the slew rate is shown in Equation 3:
SR = 0.55 × CT + 30
where
•
•
•
SR = slew rate (in µs/V)
CT = the capacitance value on the CT pin (in pF)
The units for the constant 30 are µs/V. The units for the constant 0.55 are µs/(V × pF).
(3)
This equation accounts for 10% to 90% measurement on VOUT and does not apply for CT = 0 pF. Use Table 2 to
determine rise times for when CT = 0 pF.
Rise time can be calculated by multiplying the input voltage by the slew rate. Table 2 contains rise time values
measured on a typical device.
Table 2. Rise Time Table
RISE TIME (µs) 10% - 90%, CL = 0.1 µF, CIN = 1 µF, RL = 10 Ω
(1)
CT× (pF)
VIN = 5 V
(1)
VN = 3.3 V VIN = 2.5 V VIN = 1.8 V VIN = 1.5 V VIN = 1.2 V
VIN = 1 V
0
135
95
75
60
50
45
40
220
650
455
350
260
220
185
160
470
1260
850
655
480
415
340
300
1000
2540
1680
1300
960
810
660
560
2200
5435
3580
2760
2020
1715
1390
1220
4700
12050
7980
6135
4485
3790
3120
2735
10000
26550
17505
13460
9790
8320
6815
5950
Typical values at 25°C with a 25 V X7R 10% ceramic capacitor on CT.
As the voltage across the capacitor approaches the capacitor rated voltage, the effective capacitance reduces.
Depending on the dielectric material used, the voltage coefficient changes. See Table 3 for the recommended
minimum voltage rating for the CT capacitor. If using VIN = 1.2 V or 4 V, it is recommended to use the higher of
the two CT Voltage ratings specified.
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Table 3. Recommended CT Capacitor Voltage Rating
VIN (V)
RECOMMENDED CT CAPACITOR VOLTAGE
RATING (V)
1 V to 1.2 V
10
1.2 V to 4 V
16
4 V to 5.5 V
20
8.4 Device Functional Modes
Table 4 describes the connection of the VOUT pin depending on the state of the ON pin.
Table 4. VOUT Connection
ON
QOD
CONFIGURATION
TPS22918 VOUT
L
QOD pin connected to
VOUT with REXT
GND (via REXT+RPD)
L
QOD pin tied to VOUT
directly
GND (via RPD)
L
QOD pin left open
Open
H
Any valid QOD
configuration
VIN
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9 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.
9.1 Application Information
This section highlights some of the design considerations when implementing this device in various applications.
A PSPICE model for this device is also available in the product page of this device on www.ti.com (See the
Device Support section for more information).
9.2 Typical Application
This typical application demonstrates how the TPS22918 can be used to power downstream modules.
Figure 23. Typical Application Schematic
9.2.1 Design Requirements
For this design example, use the values listed in Table 5 as the design parameters:
Table 5. Design Parameters
16
DESIGN PARAMETER
EXAMPLE VALUE
VIN
5V
Load Current
2A
CL
22 µF
Desired Fall Time
4 ms
Maximum Acceptable Inrush Current
400 mA
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9.2.2 Detailed Design Procedure
9.2.2.1 Input Capacitor (CIN)
To limit the voltage drop on the input supply caused by transient in-rush currents when the switch turns on into a
discharged load capacitor or short-circuit, a capacitor needs to be placed between VIN and GND. A 1 µF ceramic
capacitor, CIN, placed close to the pins, is usually sufficient. Higher values of CIN can be used to further reduce
the voltage drop during high-current application. When switching heavy loads, it is recommended to have an
input capacitor about 10 times higher than the output capacitor to avoid excessive voltage drop.
9.2.2.2 Output Capacitor (CL) (Optional)
Becuase of the integrated body diode in the MOSFET, a CIN greater than CL is highly recommended. A CL
greater than CIN can cause VOUT to exceed VIN when the system supply is removed. This could result in current
flow through the body diode from VOUT to VIN. A CIN to CL ratio of 10 to 1 is recommended for minimizing VIN
dip caused by inrush currents during startup.
9.2.2.3 Shutdown Sequencing During Unexpected System Power Loss
Microcontrollers and processors often have a specific shutdown sequence in which power needs to be removed.
Using the adjustable Quick Output Discharge function of the TPS22918, adding a load switch to each power rail
can be used to manage the power down sequencing in the event of an unexpected system power loss (i.e.
battery removal). To determine the QOD values for each load switch, first confirm the power down order of the
device you wish to power sequence. Be sure to check if there are voltage or timing margins that must be
maintained during power down. Next, consult QOD Fall Time Table in the Quick Output Discharge (QOD) feature
description to determine appropriate COUT and RQOD values for each power rail's load switch so that the load
switches' fall times correspond to the order in which they need to be powered down. In the above example, we
would like this power rail's fall time to be 4 ms. Using Equation 2, to determine the appropriate RQOD to achieve
our desired fall time.
Because fall times are measured from 90% of VOUT to 10% of VOUT, the equation becomes:
.5 V = 4.5 V × e-(4 ms) / (R × (22 µF))
RQOD = 83.333 Ω
(4)
(5)
Refer to Figure 7, RPD at VIN = 5 V is approximately 25 Ω. Using Equation 1, the required external QOD
resistance can be calculated:
83.333 Ω = 25 Ω + REXT
REXT = 58.333 Ω
(6)
(7)
Figure 24 through Figure 29 are scope shots demonstrating an example of the QOD functionality when power is
removed from the device (both ON and VIN are disconnected simultaneously). The input voltage is decaying in
all scope shots below.
• Initial VIN = 3.3 V
• QOD = Open, 500 Ω, or shorted to VOUT
• CL = 1 μF, 10 μF
• VOUT is left floating
NOTE: VIN may appear constant in some figures. This is because the time scale of the scope shot is too small to
show the decay of CIN.
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VIN = 3.3 V
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CIN = 1 µF
QOD = Open
CL = 1 µF
VIN = 3.3 V
Figure 24. Fall Time (tF) at VIN = 3.3 V
VIN = 3.3 V
CIN = 1 µF
QOD = VOUT
CL = 1 µF
CIN = 1 µF
QOD = 500 Ω
VIN = 3.3 V
CIN = 1 µF
QOD = Open
CL = 10 µF
Figure 27. Fall Time (tF) at VIN = 3.3 V
CL = 10 µF
VIN = 3.3 V
Figure 28. Fall Time (tF) at VIN = 3.3 V
18
CL = 1 µF
Figure 25. Fall Time (tF) at VIN = 3.3 V
Figure 26. Fall Time (tF) at VIN = 3.3 V
VIN = 3.3 V
CIN = 1 µF
QOD = 500 Ω
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CIN = 1 µF
QOD = VOUT
CL = 10 µF
Figure 29. Fall Time (tF) at VIN = 3.3 V
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9.2.2.4 VIN to VOUT Voltage Drop
The VIN to VOUT voltage drop in the device is determined by the RON of the device and the load current. The
RON of the device depends upon the VIN conditions of the device. Refer to the RON specification of the device in
the Electrical Characteristics table of this data sheet. When the RON of the device is determined based upon the
VIN conditions, use Equation 8 to calculate the VIN to VOUT voltage drop:
∆V = ILOAD × RON
where
•
•
•
ΔV = voltage drop from VIN to VOUT
ILOAD = load current
RON = On-resistance of the device for a specific VIN
An appropriate ILOAD must be chosen such that the IMAX specification of the device is not violated.
(8)
9.2.2.5 Inrush Current
Use Equation 9 to determine how much inrush current will be caused by the CL capacitor:
dV
IINRUSH = CL ´ OUT
dt
where
•
•
•
•
IINRUSH = amount of inrush caused by CL
CL = capacitance on VOUT
dt = Output Voltage rise time during the ramp up of VOUT when the device is enabled
dVOUT = change in VOUT during the ramp up of VOUT when the device is enabled
(9)
The appropriate rise time can be calculated using the design requirements and the inrush current equation. As
we are calculating the rise time (measured from 10% to 90% of VOUT), we will account for this in our dVOUT
parameter (80% of VOUT = 4 V).
400 mA = 22 pF × 4 V/dt
dt = 220 μs
(10)
(11)
To ensure an inrush current of less than 400 mA, choose a CT value that will yield a rise time of more than 220
μs. Consulting Table 2 at VIN = 5 V, CT = 220 pF will provide a typical rise time of 650 μs. Inputting this rise time
and voltage into Equation 9, yields:
IInrush = 22 pF × 4 V / 650 μs
IInrush = 135 mA
(12)
(13)
This inrush current can be seen in the Application Curves section. An appropriate CL value should be placed on
VOUT such that the IMAX and IPLS specifications of the device are not violated.
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9.2.3 Application Curves
VIN = 5 V
CL = 22 pF
CT = 0 pF
VIN = 5 V
Figure 30. TPS22918 Inrush Current
CL = 22 pF
CT = 220 pF
Figure 31. TPS22918 Inrush Current
10 Power Supply Recommendations
The device is designed to operate from a VIN range of 1 V to 5.5 V. This supply must be well regulated and
placed as close to the device terminal as possible with the recommended 1-µF bypass capacitor. If the supply is
located more than a few inches from the device terminals, additional bulk capacitance may be required in
addition to the ceramic bypass capacitors. If additional bulk capacitance is required, an electrolytic, tantalum, or
ceramic capacitor of 1 µF may be sufficient.
The TPS22918 operates regardless of power sequencing order. The order in which voltages are applied to VIN
and ON will not damage the device as long as the voltages do not exceed the absolute maximum operating
conditions. If voltage is applied to ON before VIN, the slew rate of VOUT will not be controlled.
11 Layout
11.1 Layout Guidelines
VIN and VOUT traces should be as short and wide as possible to accommodate for high current.
The VIN pin should be bypassed to ground with low ESR ceramic bypass capacitors. The typical recommended
bypass capacitance is 1-µF ceramic with X5R or X7R dielectric. This capacitor must be placed as close to the
device pins as possible.
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11.2 Layout Example
1
VIN
VOUT
6
2
GND
QOD
5
3
ON
CT
4
VIA to Power Ground Plane
Figure 32. Recommended Board Layout
11.3 Thermal Considerations
For best performance, all traces must be as short as possible. To be most effective, the input and output
capacitors must be placed close to the device to minimize the effects that parasitic trace inductances may have
on normal and short-circuit operation. Using wide traces for VIN, VOUT, and GND helps minimize the parasitic
electrical effects along with minimizing the case to ambient thermal impedance.
The maximum IC junction temperature should be restricted to 125°C under normal operating conditions. To
calculate the maximum allowable dissipation, PD(max) for a given output current and ambient temperature, use
Equation 14:
TJ(MAX) - TA
PD(MAX) =
qJA
where
•
•
•
•
PD(MAX) = maximum allowable power dissipation
TJ(MAX) = maximum allowable junction temperature (125°C for the TPS22918)
TA = ambient temperature of the device
θJA = junction to air thermal impedance. Refer to the Thermal Information table. This parameter is highly
dependent upon board layout.
(14)
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12 Device and Documentation Support
12.1 Device Support
12.1.1 Developmental Support
For the TPS22918 PSpice Transient Model, see SLVMBI6.
12.2 Documentation Support
12.2.1 Related Documentation
For related documentation see the following:
TPS22918 5.5-V, 2-A, 50-mΩ On-Resistance Load Switch Evaluation Module, SLVUAP0.
12.3 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.4 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
12.5 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
12.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
TPS22918DBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAU | SN
Level-2-260C-1 YEAR
-40 to 105
13MW
TPS22918DBVT
ACTIVE
SOT-23
DBV
6
250
RoHS & Green
NIPDAU | SN
Level-2-260C-1 YEAR
-40 to 105
13MW
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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