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TPS73801
SLVS915C – FEBRUARY 2010 – REVISED JULY 2015
TPS73801 1.0-A Low-Noise Fast-Transient-Response Low-Dropout Regulator
1 Features
3 Description
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The TPS73801 is a low-dropout (LDO) regulator
optimized for fast transient response. The device can
supply 1.0 A of output current with a dropout voltage
of 300 mV. Operating quiescent current is 1 mA,
dropping to less than 1 µA in shutdown. Quiescent
current is well controlled; it does not rise in dropout
as it does with many other regulators. In addition to
fast transient response, the TPS73801 regulators
have very low output noise, which makes them ideal
for sensitive RF supply applications.
1
Optimized for Fast Transient Response
Output Current: 1.0 A
Dropout Voltage: 300 mV
Low Noise: 45 µVRMS (10 Hz to 100 kHz)
1-mA Quiescent Current
No Protection Diodes Needed
Controlled Quiescent Current in Dropout
Adjustable Output Voltage: 1.21 to 20 V
Less Than 1-µA Quiescent Current in Shutdown
Stable With 10-µF Output Capacitor
Stable With Ceramic Capacitors
Reverse-Battery Protection
No Reverse Current
Thermal Limiting
2 Applications
•
•
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3.3-V to 2.5-V Logic Power Supplies
Post Regulator for Switching Supplies
Portable/Battery-Powered Equipment.
Output voltage range is from 1.21 to 20 V. The
TPS73801 regulators are stable with output
capacitors as low as 10 µF. Small ceramic capacitors
can be used without the necessary addition of ESR,
as is common with other regulators. Internal
protection
circuitry
includes
reverse-battery
protection, current limiting, thermal limiting, and
reverse-current protection. The devices are available
as an adjustable device with a 1.21-V reference
voltage. The TPS73801 regulators are available in
the 6-pin TO-223 (DCQ) packages.
Device Information(1)
PART NUMBER
TPS73801
PACKAGE
SOT-223 (6)
BODY SIZE (NOM)
6.50 mm x 3.50 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
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.
TPS73801
SLVS915C – FEBRUARY 2010 – REVISED JULY 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
7
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
4
4
4
4
5
7
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 11
7.1 Overview ................................................................. 11
7.2 Functional Block Diagram ....................................... 11
7.3 Feature Description................................................. 11
7.4 Device Functional Modes........................................ 13
8
Application and Implementation ........................ 14
8.1 Application Information............................................ 14
8.2 Typical Application .................................................. 14
9 Power Supply Recommendations...................... 16
10 Layout................................................................... 16
10.1 Layout Guidelines ................................................. 16
10.2 Layout Example .................................................... 17
10.3 Thermal Considerations ........................................ 17
11 Device and Documentation Support ................. 19
11.1
11.2
11.3
11.4
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
19
19
19
19
12 Mechanical, Packaging, and Orderable
Information ........................................................... 19
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (October 2014) to Revision C
Page
•
Moved storage temperature to the Absolute Maximum Ratings ........................................................................................... 4
•
Changed Handling Ratings to ESD Ratings and updated units from kV to V ........................................................................ 4
•
Added Community Resources ............................................................................................................................................. 19
Changes from Revision A (July 2012) to Revision B
•
2
Page
Added Handling Rating table, Feature Description section, Device Functional Modes, Application and
Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation
Support section, and Mechanical, Packaging, and Orderable Information section ............................................................... 1
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5 Pin Configuration and Functions
GND
DCQ Package
SOT-223
Top View
6
5
4
3
2
1
EN
FB
GND
OUT
IN
Pin Functions
PIN
NO.
NAME
I/O
DESCRIPTION
1
IN
—
Input. Power is supplied to the device through the IN pin. A bypass capacitor is required on this pin if
the device is more than six inches away from the main input filter capacitor. In general, the output
impedance of a battery rises with frequency, so it is advisable to include a bypass capacitor in batterypowered circuits. A bypass capacitor (ceramic) in the range of 1 µF to 10 µF is sufficient. The
TPS73801 regulators are designed to withstand reverse voltages on the IN pin with respect to ground
and the OUT pin. In the case of a reverse input, which can happen if a battery is plugged in
backwards, the device acts as if there is a diode in series with its input. There is no reverse current
flow into the regulator, and no reverse voltage appears at the load. The device protects both itself and
the load.
2
OUT
—
Output. The output supplies power to the load. A minimum output capacitor (ceramic) of 10 µF is
required to prevent oscillations. Larger output capacitors are required for applications with large
transient loads to limit peak voltage transients.
3
GND
—
Ground
4
FB
IN
Feedback. This is the input to the error amplifier. This pin is internally clamped to ±7 V. It has a bias
current of 3 µA that flows into the pin. The FB pin voltage is 1.21 V referenced to ground, and the
output voltage range is 1.21 V to 20 V.
5
EN
IN
Enable. The EN pin is used to put the TPS73801 regulators into a low-power shutdown state. The
output is off when the EN pin is pulled low. The EN pin can be driven either by 5-V logic or opencollector gate, normally several microamperes, and the EN pin current, typically 3 µA. If unused, the
EN pin must be connected to the IN pin. The device is in the low-power shutdown state if the EN pin is
not connected.
6
GND
—
Ground
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
–20
20
V
–20
20
V
–20
20
V
FB
–7
7
V
EN
–20
20
V
IN
OUT
VIN
Input voltage
Input-to-output differential
(2)
tshort
Output short-circuit duration
TJ
Operating virtual-junction temperature
–40
125
°C
Tstg
Storage temperature
–65
150
°C
(1)
(2)
Indefinite
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.
Absolute maximum input-to-output differential voltage cannot be achieved with all combinations of rated IN pin and OUT pin voltages.
With the IN pin at 20 V, the OUT pin may not be pulled below 0 V. The total measured voltage from IN to OUT cannot exceed ±20 V.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins
(1)
UNIT
2000
Charged device model (CDM), per JEDEC specification JESD22-C101, all pins
(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)
VIN
Input voltage range
VIH
EN high-level input voltage
VIL
EN low-level input voltage
TJ
Recommended operating junction temperature range
MIN
MAX
VOUT + VDO
20
V
2
20
V
0.25
V
125
°C
–40
UNIT
6.4 Thermal Information
TPS73801
THERMAL METRIC
(1)
DCQ (SOT-223)
UNIT
6 PINS
RθJA
Junction-to-ambient thermal resistance
50.5
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
31.1
°C/W
RθJB
Junction-to-board thermal resistance
5.1
°C/W
ψJT
Junction-to-top characterization parameter
1.0
°C/W
ψJB
Junction-to-board characterization parameter
5.0
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
—
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
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6.5 Electrical Characteristics
Over operating temperature range TJ = –40°C to 125°C (unless otherwise noted) (1)
PARAMETER
VIN
Input voltage
TEST CONDITIONS
(3) (4)
FB pin voltage
(3) (5)
TPS73801
1.9
20
1.21
1.228
VIN = 2.5 V to 20 V,
ILOAD = 1 mA to 1.0A
Full range
1.174
1.21
1.246
Full range
1.5
5
2
8
TPS73801
(3)
ΔVIN = 2.21 V to 20 V,
ILOAD = 1 mA
Load regulation
TPS73801
(3)
VIN = 2.5 V,
ΔILOAD = 1 mA to 1.0 A
ILOAD = 100 mA
ILOAD = 500 mA
ILOAD = 1.0 A
VN
GND pin current (7) (8)
VIN = VOUT(NOMINAL) + 1
Output voltage noise
FB pin bias current
VEN
Shutdown threshold
IEN
EN pin current
25°C
Full range
18
25°C
0.02
Full range
0.1
Full range
0.19
Full range
25°C
0.27
0.24
ILOAD = 1 mA
Full range
1.1
1.6
ILOAD = 100 mA
Full range
3.8
5.5
ILOAD = 500 mA
Full range
15
25
ILOAD = 1.0 A
Full range
35
80
25°C
45
25°C
3
10
0.9
2
0.25
0.75
25°C
0.01
1
VEN = 20 V
25°C
3
30
Quiescent current in shutdown
VIN = 6 V, VEN = 0 V
25°C
0.01
1
PSRR
Ripple rejection
VIN – VOUT = 1.5 V (avg), VRIPPLE = 0.5 VP-P,
fRIPPLE = 120 Hz, ILOAD = 0.75 A
25°C
ICL
Current limit
IREV
Input reverse leakage current
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
55
25°C
VIN = VOUT(NOMINAL) + 1
Full range
VIN = –20 V, VOUT = 0 V
Full range
mA
µVRMS
VEN = 0 V
VIN = 7 V, VOUT = 0 V
V
0.40
1.5
Full range
mV
0.30
1
Full range
mV
0.35
Full range
VOUT = ON to OFF
V
0.17
0.22
25°C
VOUT = OFF to ON
V
0.10
25°C
Full range
COUT = 10 µF, ILOAD = 1.0 A,
BW = 10 Hz to 100 kHz
UNIT
0.06
ILOAD = 0 mA
(3) (9)
IFB
MAX
2.2
Dropout voltage
VIN = VOUT(NOMINAL)
IGND
(2)
1.192
ILOAD = 1 mA
VDO
TYP
25°C
Line regulation
(4) (6) (7)
MIN
25°C
VIN = 2.21 V, ILOAD = 1 mA
VFB
TJ
63
µA
V
µA
µA
dB
2
A
1.6
1
mA
The TPS73801 regulators are tested and specified under pulse load conditions such that TJ is approximately equal to TA. The
TPS73801 is fully tested at TA = 25°C. Performance at –40°C and 125°C is specified by design, characterization, and correlation with
statistical process controls.
Typical values represent the likely parametric nominal values determined at the time of characterization. Typical values depend on the
application and configuration and may vary over time. Typical values are not ensured on production material.
The TPS73801 is tested and specified for these conditions with the FB pin connected to the OUT pin.
Dropout voltages are limited by the minimum input voltage specification under some output voltage/load conditions.
Operating conditions are limited by maximum junction temperature. The regulated output voltage specification does not apply for all
possible combinations of input voltage and output current. When operating at maximum input voltage, the output current range must be
limited. When operating at maximum output current, the input voltage range must be limited.
Dropout voltage is the minimum input to output voltage differential needed to maintain regulation at a specified output current. In
dropout, the output voltage is equal to: VIN – VDROPOUT.
To satisfy requirements for minimum input voltage, the TPS73801 is tested and specified for these conditions with an external resistor
divider (two 4.12-kΩ resistors) for an output voltage of 2.4 V. The external resistor divider adds a 300-mA DC load on the output.
GND pin current is tested with VIN = (VOUT(NOMINAL) + 1 V) and a current source load. The GND pin current decreases at higher input
voltages.
FB pin bias current flows into the FB pin.
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Electrical Characteristics (continued)
Over operating temperature range TJ = –40°C to 125°C (unless otherwise noted)(1)
PARAMETER
IRO
Reverse output current
TEST CONDITIONS
(10)
TPS73801
VOUT = 1.21 V, VIN < 1.21 V
TJ
25°C
MIN
(2)
MAX
UNIT
300
600
µA
TYP
(10) Reverse output current is tested with the IN pin grounded and the OUT pin forced to the rated output voltage. This current flows into the
OUT pin and out the GND pin.
6
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6.6 Typical Characteristics
400
400
350
350
300
Dropout Voltage – mV
300
Dropout Voltage – mV
IOUT = 1 A
TA = 125°C
250
200
TA = 25°C
150
250
IOUT = 0.5 A
200
150
100
100
50
50
0
0
IOUT = 100 mA
IOUT = 1 mA
0
0.2
0.4
0.6
0.8
-50
1
-25
25
50
75
100
125
Figure 1. Dropout Voltage vs Output Current
Figure 2. Dropout Voltage vs Temperature
1.5
1.23
1.4
VOUT Adjustable
1.225
IOUT = 1 mA
1.3
VIN = 6 V
1.22
1.2
Output Voltage – V
Quiescent Current – mA
0
TA – Free-Air Temperature – °C
Output Current – A
1.1
1
0.9
1.215
1.21
1.205
0.8
1.2
0.7
1.195
0.6
0.5
-50
-25
0
25
50
75
100
1.19
-50
125
-25
TA – Free-Air Temperature – °C
VIN = 6 V
VEN = VIN
IOUT = 0 A
TPS73801
VIN = 6 V
Figure 3. Quiescent Current vs Temperature
25
50
75
100
125
IOUT = 1 mA
TPS73801
Figure 4. Output Voltage vs Temperature
1.2
100
TJ = 25°C
90
ROUT = 4.3 k W
1
VSHDN = VIN
80
VOUT Adjustable
Ground Current – mA
Quiescent Current – mA
0
TA – Free-Air Temperature – °C
0.8
0.6
0.4
70
60
50
40
IOUT = 1 A
30
20
0.2
IOUT = 0.5 A
10
0
0
0
2
4
6
8
10
12
14
16
18
0
20
1
Input Voltage – V
TJ = 25 °C
VEN = VIN
ROUT = 4.3 kΩ
2
3
4
5
6
7
8
9
10
Input Voltage – V
TPS73801
Figure 5. Quiescent Current vs Input Voltage
TJ = 25 °C
VEN = VIN
VOUT = 1.21 V
TPS73801
Figure 6. Ground Current vs Input Voltage
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Typical Characteristics (continued)
80
10
TJ = 25°C
VIN = VOUT(nom) + 1
70
VSHDN = VIN
VOUT Adjustable
8
60
Ground Current – mA
Ground Current – mA
VOUT = 1.21 V
6
IOUT = 300 mA
4
50
40
30
IOUT = 100 mA
20
2
10
IOUT = 10 mA
0
0
0
1
2
3
4
5
6
7
8
9
0
10
0.2
0.4
Input Voltage – V
TJ = 25 °C
VEN = VIN
0.6
0.8
1
Output Current – A
VOUT = 1.21 V
TPS73801
Figure 7. Ground Current vs Input Voltage
VIN = VOUT(nom) + 1
Figure 8. Ground Current vs Output Current
2.5
2.25
EN Input Current – µA
2
1.75
1.5
1.25
1
0.75
0.5
0.25
0
0
2
4
6
8
10
12
14
16
18
20
EN Input Voltage – V
VEN = 0 V
Figure 9. EN Input Current vs Temperature
Figure 10. EN Input Current vs EN Input Voltage
1
1
0.9
IOUT = 1 mA
IOUT = 1 mA
0.9
0.8
EN Input Voltage – V
EN Input Voltage – V
0.8
0.7
0.6
0.5
0.4
0.3
0.6
0.5
0.4
0.3
0.2
0.2
0.1
0.1
0
0
-50
-25
0
25
50
75
100
-50
125
-25
0
25
50
75
100
125
TA – Free-Air Temperature – °C
TA – Free-Air Temperature – °C
8
0.7
IOUT = 1 mA
IOUT = 1 mA
Figure 11. EN Threshold (Off to On) vs Temperature
Figure 12. EN Threshold (On to Off) vs Temperature
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Typical Characteristics (continued)
3.5
5
D
?VOUT = 100 mV
4.5
3
TA = -40°C
2.5
Current Limit – A
FB Bias Current – µA
4
3.5
3
2.5
2
TA = 25°C
2
TA = 125°C
1.5
1.5
1
1
0.5
0.5
0
0
-50
-25
0
25
50
75
100
0
125
2
TA – Free-Air Temperature – °C
4
6
8
10
12
14
16
18
20
Input/Output Differential Voltage – V
ΔVOUT = 100 mV
Figure 13. Fb Bias Current vs Temperature
Figure 14. Current Limit vs Input/Output Differential Voltage
12
5
VIN = 7 V
10
VOUT = 0 V
Reverse Output Current – mA
Current Limit – A
4
3
2
1
8
6
4
2
0
-2
0
-50
-25
0
25
50
75
TA – Free-Air Temperature – °C
VIN = 7 V
100
0
125
2
4
6
8
10
Output Voltage – V
TJ = 25 °C
VIN = 0 V
Current flows into OUT pin
VOUT = 0 V
Figure 15. Current Limit vs Temperature
Figure 16. Reverse Output Current vs Output Voltage
80
1000
60
Ripple Rejection – dB
Reverse Output Current – µA
70
800
600
400
TPS73801
VOUT = 1.21 V
50
40
30
VIN = 2.7 V
CIN = 0
20
200
COUT = 10 µF
IOUT = 750 mA
10
VRipple = 0.05 Vpp
0
-50
0
-25
0
25
50
75
100
125
10
TA – Free-Air Temperature – °C
100
1k
1000
10k
10000
100k
100000
1M
1000000
Frequency – Hz
VIN = 0 V
VIN = 2.7 V
CIN = 0
Figure 17. Reverse Output Current vs Temperature
VRIPPLE = 0.05 VPP
COUT = 10 µF (ceramic)
IOUT = 750 mA
TA = 25 °C
Figure 18. Ripple Rejection vs Frequency
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Typical Characteristics (continued)
20
1
15
5
TPS73801
Output Noise Voltage – µVRMS
Load Regulation – mV
10
0
-5
-10
-15
-20
0.1
-25
-30
-35
0.01
-50
-25
0
25
50
75
TA – Free-Air Temperature – °C
100
125
10
100
10k
100k
COUT = 10 µF (ceramic)
IOUT = 1 A
Figure 19. Load Regulation vs Temperature
VIN = 4.3 V
1k
Frequency – Hz
CIN = 10 µF
COUT = 10 µF (ceramic)
Figure 20. Output Noise Voltage vs Frequency
VIN = 4.3 V
CIN = 10 µF
COUT = 10 µF (ceramic)
Figure 22. Load Transient Response
Figure 21. Load Transient Response
IOUT = 1.5 A
IOUT = 1 A
CIN = 10 µF
COUT = 10 µF (ceramic)
Figure 23. Line Transient Response
10
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7 Detailed Description
7.1 Overview
The TPS73801 is a 1.0-A LDO regulator optimized for fast transient response. The devices are capable of
supplying 1.0 A at a dropout voltage of 300 mV. The low operating quiescent current (1 mA) drops to less than
1 µA in shutdown. In addition to the low quiescent current, the TPS73801 regulators incorporate several
protection features which make them ideal for use in battery-powered systems. The devices are protected
against both reverse input and reverse output voltages. In battery-backup applications where the output can be
held up by a backup battery when the input is pulled to ground, the TPS73801 acts as if it has a diode in series
with its output and prevents reverse current flow. Additionally, in dual-supply applications where the regulator
load is returned to a negative supply, the output can be pulled below ground by as much as 20 V and still allow
the device to start and operate.
7.2 Functional Block Diagram
7.3 Feature Description
7.3.1 Adjustable Operation
The TPS73801 has an adjustable output voltage range of 1.21 V to 20 V. The output voltage is set by the ratio of
two external resistors as shown in Figure 24. The device maintains the voltage at the FB pin at 1.21 V
referenced to ground. The current in R1 is then equal to (1.21 V/R1), and the current in R2 is the current in R1
plus the FB pin bias current. The FB pin bias current, 3 μA at 25 °C, flows through R2 into the FB pin. The output
voltage can be calculated using the formula shown in Equation 1. The value of R1 should be less than 4.17 kΩ to
minimize errors in the output voltage caused by the FB pin bias current. Note that in shutdown the output is
turned off, and the divider current is zero.
Figure 24. Adjustable Operation
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The output voltage can be set using the following equations:
VOUT = 1.21 V(1 + R2
) + IFB ´ R2
R1
(1)
(2)
(3)
(4)
VFB = 1.21 V
IFB = 3 µA at 25 °C
Output Range = 1.21 to 20 V
7.3.2 Fixed Operation
The TPS73801 can be used in a fixed voltage configuration. By connecting the FB pin to OUT the TPS73801 will
regulate the output to 1.21 V. During fixed voltage operation, the FB pin can be used for a Kelvin connection if
routed separately to the load. This allows the regulator to compensate for voltage drop across parasitic
resistances (RP) between the output and the load. This becomes more crucial with higher load currents.
Figure 25. Kelvin Sense Connection
7.3.3 Overload Recovery
Like many IC power regulators, the TPS73801 has safe operating area protection. The safe area protection
decreases the current limit as input-to-output voltage increases and keeps the power transistor inside a safe
operating region for all values of input-to-output voltage. The protection is designed to provide some output
current at all values of input-to-output voltage up to the device breakdown.
When power is first turned on, as the input voltage rises, the output follows the input, allowing the regulator to
start up into very heavy loads. During start up, as the input voltage is rising, the input-to-output voltage
differential is small, allowing the regulator to supply large output currents. With a high input voltage, a problem
can occur wherein removal of an output short does not allow the output voltage to recover. Other regulators also
exhibit this phenomenon, so it is not unique to the TPS73801.
The problem occurs with a heavy output load when the input voltage is high and the output voltage is low.
Common situations occur immediately after the removal of a short circuit or when the shutdown pin is pulled high
after the input voltage has already been turned on. The load line for such a load may intersect the output current
curve at two points. If this happens, there are two stable output operating points for the regulator. With this
double intersection, the input power supply may need to be cycled down to zero and brought up again to make
the output recover.
7.3.4 Output Voltage Noise
The TPS73801 regulators have been designed to provide low output voltage noise over the 10-Hz to 100-kHz
bandwidth while operating at full load. Output voltage noise is typically 40 nV/√Hz over this frequency bandwidth
for the TPS73801. For higher output voltages (generated by using a resistor divider), the output voltage noise is
gained up accordingly. This results in RMS noise over the 10-Hz to 100-kHz bandwidth of 14 μVRMS for the
TPS73801.
Higher values of output voltage noise may be measured when care is not exercised with regards to circuit layout
and testing. Crosstalk from nearby traces can induce unwanted noise onto the output of the TPS73801.
Powersupply ripple rejection must also be considered; the TPS73801 regulators do not have unlimited powersupply rejection and pass a small portion of the input noise through to the output.
12
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7.3.5 Protection Features
The TPS73801 regulators incorporate several protection features that make them ideal for use in batterypowered circuits. In addition to the normal protection features associated with monolithic regulators, such as
current limiting and thermal limiting, the devices are protected against reverse input voltages, reverse output
voltages and reverse voltages from output to input.
Current limit protection and thermal overload protection are intended to protect the device against current
overload conditions at the output of the device. For normal operation, the junction temperature should not exceed
125°C.
The input of the device withstands reverse voltages of 20 V. Current flow into the device is limited to less than 1
mA (typically less than 100 μA), and no negative voltage appears at the output. The device protects both itself
and the load. This provides protection against batteries that can be plugged in backward.
The output of the TPS73801 can be pulled below ground without damaging the device. If the input is left open
circuit or grounded, the output can be pulled below ground by 20 V. The output acts like an open circuit; no
current flows out of the pin. If the input is powered by a voltage source, the output sources the short-circuit
current of the device and protects itself by thermal limiting. In this case, grounding the EN pin turns off the device
and stops the output from sourcing the short-circuit current.
The FB pin can be pulled above or below ground by as much as 7 V without damaging the device. If the input is
left open circuit or grounded, the FB pin acts like an open circuit when pulled below ground and like a large
resistor (typically 5 kΩ) in series with a diode when pulled above ground.
In situations where the FB pin is connected to a resistor divider that would pull the FB pin above its 7-V clamp
voltage if the output is pulled high, the FB pin input current must be limited to less than 5 mA. For example, a
resistor divider is used to provide a regulated 1.5-V output from the 1.21-V reference when the output is forced to
20 V. The top resistor of the resistor divider must be chosen to limit the current into the FB pin to less than 5 mA
when the FB pin is at 7 V. The 13-V difference between OUT and FB pins divided by the 5-mA maximum current
into the FB pin yields a minimum top resistor value of 2.6 kΩ.
In circuits where a backup battery is required, several different input/output conditions can occur. The output
voltage may be held up while the input is either pulled to ground, pulled to some intermediate voltage, or is left
open circuit. When the IN pin of the TPS73801 is forced below the OUT pin or the OUT pin is pulled above the
IN pin, input current typically drops to less than 2 μA. This can happen if the input of the device is connected to a
discharged (low voltage) battery and the output is held up by either a backup battery or a second regulator
circuit. The state of the EN pin has no effect on the reverse output current when the output is pulled above the
input.
7.4 Device Functional Modes
See the device modes in Table 1.
Table 1. Device Modes
EN
DEVICE STATE
H
Regulated voltage
L
Shutdown
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8 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.
8.1 Application Information
8.1.1 Output Capacitance and Transient Response
The TPS73801 regulators are designed to be stable with a wide range of output capacitors. The ESR of the
output capacitor affects stability, most notably with small capacitors. A minimum output capacitor of 10 μF with
an ESR of 3 Ω or less is recommended to prevent oscillations. Larger values of output capacitance can decrease
the peak deviations and provide improved transient response for larger load current changes. Bypass capacitors,
used to decouple individual components powered by the TPS73801, increase the effective output capacitor
value.
Extra consideration must be given to the use of ceramic capacitors. Ceramic capacitors are manufactured with a
variety of dielectrics, each with different behavior over temperature and applied voltage. The most common
dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high
capacitances in a small package, but exhibit strong voltage and temperature coefficients. When used with a 5-V
regulator, a 10-μF Y5V capacitor can exhibit an effective value as low as 1 μF to 2 μF over the operating
temperature range. The X5R and X7R dielectrics result in more stable characteristics and are more suitable for
use as the output capacitor. The X7R type has better stability across temperature, while the X5R is less
expensive and is available in higher values.
Voltage and temperature coefficients are not the only sources of problems. Some ceramic capacitors have a
piezoelectric response. A piezoelectric device generates voltage across its terminals due to mechanical stress,
similar to the way a piezoelectric accelerometer or microphone works. For a ceramic capacitor, the stress can be
induced by vibrations in the system or thermal transients.
8.2 Typical Application
This section will highlight some of the design considerations when implementing this device in various
applications.
NOTE: All capacitors are ceramic.
Figure 26. Adjustable Output Voltage Operation
14
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Typical Application (continued)
8.2.1 Design Requirements
Table 2 shows the design parameters for this application.
Table 2. Design Parameters
DESIGN PARAMETER
Input voltage (VIN)
EXAMPLE VALUE
5.0 V
Output voltage (VOUT)
2.5 V
Output current (IOUT)
0 to 1 A
Load regulation
1%
8.2.2 Detailed Design Procedure
The TPS73801 has an adjustable output voltage range of 1.21 to 20 V. The output voltage is set by the ratio of
two external resistors R1 and R2 as shown in Figure 26. The device maintains the voltage at the FB pin at 1.21
V referenced to ground. The current in R1 is then equal to (1.21 V/R1), and the current in R2 is the current in R1
plus the FB pin bias current. The FB pin bias current, 3 µA at 25 °C, flows through R2 into the FB pin. The output
voltage can be calculated using Equation 5.
VOUT = 1.21 V(1 + R2
) + IFB ´ R2
R1
(5)
The value of R1 should be less than 4.17 kΩ to minimize errors in the output voltage caused by the FB pin bias
current. Note that in shutdown the output is turned off, and the divider current is zero. For an output voltage of
2.50 V, R1 will be set to 4.0 kΩ. R2 is then found to be 4.22 kΩ using the equation above.
4.22kW
VOUT = 1.21V(1 +
) + 3µA ´ 4.22kW
4.0kW
(6)
VOUT = 2.50 V
(7)
The adjustable device is tested and specified with the FB pin tied to the OUT pin for an output voltage of 1.21 V.
Specifications for output voltages greater than 1.21 V are proportional to the ratio of the desired output voltage to
1.21 V: VOUT/1.21 V. For example, load regulation for an output current change of 1 mA to 1.5 A is –2 mV (typ) at
VOUT = 1.21 V. At VOUT = 2.50 V, the typical load regulation is:
(2.50 V/1.21 V)(–2 mV) = –4.13 mV
(8)
Figure 27 shows the actual change in output is about 3 mV for a 1-A load step. The maximum load regulation at
25°C is –8 mV. At VOUT = 2.50 V, the maximum load regulation is:
(2.50 V/1.21 V)(–8 mV) = –16.53 mV
(9)
Since 16.53 mV is only 0.7% of the 2.5 V output voltage, the load regulation will meet the design requirements.
8.2.3 Application Curve
Figure 27. 1-A Load Transient Response
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9 Power Supply Recommendations
The device is designed to operate with an input voltage supply up to 20 V. The minimum input voltage should
provide adequate headroom greater than the dropout voltage in order for the device to have a regulated output. If
the input supply is noisy, additional input capacitors with low ESR can help improve the output noise
performance.
10 Layout
10.1 Layout Guidelines
1. For best performance, all traces should be as short as possible.
2. Use wide traces for IN, OUT, and GND to minimize the parasitic electrical effects.
3. A minimum output capacitor of 10 μF with an ESR of 3 Ω or less is recommended to prevent oscillations.
X5R and X7R dielectrics are preferred.
4. Place the Output Capacitor as close as possible to the OUT pin of the device.
5. The tab of the DCQ package should be connected to ground.
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10.2 Layout Example
VOUT = 1.21 V(1 + R2
) + IFB ´ R2
R1
Figure 28. SOT-223 Layout Example (DCQ)
10.3 Thermal Considerations
The power handling capability of the device is limited by the recommended maximum operating junction
temperature (125 °C). The power dissipated by the device is made up of two components:
1. Output current multiplied by the input/output voltage differential: IOUT(VIN – VOUT)
2. GND pin current multiplied by the input voltage: IGNDVIN
The GND pin current can be found using the GND Pin Current graphs in Typical Characteristics. Power
dissipation is equal to the sum of the two components listed above.
The TPS73801 series regulators have internal thermal limiting designed to protect the device during overload
conditions. For continuous normal conditions, the recommended maximum operating junction temperature is 125
°C. It is important to give careful consideration to all sources of thermal resistance from junction to ambient.
Additional heat sources mounted nearby must also be considered.
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10.3.1 Calculating Junction Temperature
Example: Given an output voltage of 3.3 V, an input voltage range of 4 V to 6 V, an output current range of 0 mA
to 500 mA, and a maximum ambient temperature of 50°C, what is the operating junction temperature?
The power dissipated by the device is equal to:
IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX))
where
•
•
•
IOUT(MAX) = 500 mA
VIN(MAX) = 6 V
IGND at (IOUT = 500 mA, VIN = 6 V) = 10 mA
(10)
So,
P = 500 mA × (6 V – 3.3 V) + 10 mA × 6 V = 1.41 W
(11)
The thermal resistance of the DCQ package is 50.5°C/W. So the junction temperature rise above ambient is
approximately equal to:
1.41W × 50.5°C/W = 71.2°C
(12)
The junction temperature rise can then be added to the maximum ambient temperature to find the operating
junction temperature (TJ):
TJ = 50°C + 71.2°C = 121.2°C
18
(13)
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11 Device and Documentation Support
11.1 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.
11.2 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.3 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.
11.4 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 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)
TPS73801DCQR
ACTIVE
SOT-223
DCQ
6
2500
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
PS73801
(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
