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TPS7A3501
SBVS228B – JULY 2013 – REVISED MARCH 2015
TPS7A3501 High PSRR, Low-Noise, 1-A Power Filter
1 Features
2 Applications
•
•
•
•
•
•
•
•
1
•
•
•
•
•
•
•
•
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Regulates Input-to-Output Voltage:
– User-Programmable Input-to-Output Voltage
Regulation Range:
200 mV to 500 mV
Power-Supply Rejection Ratio:
– 42 dB at 1 MHz
– ≥ 32 dB (360 kHz to 3.9 MHz)
Low-Noise Output:
– 3.8 µVRMS (10 Hz to 100 kHz)
Output Current: Up to 1 A
Output Voltage Range: 1.21 V to 4.5 V
Excellent Load Transient Response
Stable With Ceramic Capacitors as Low as
10 µF
Current Limit and Thermal Shutdown for
Fault Protection
Available in a Low Thermal Resistance Package:
2-mm × 2-mm WSON-6
Operating Temperature Range:
–40°C to 125°C
Post DC-DC Converter Ripple Filtering
Base Stations and Telecom Infrastructure
Professional Audio
Communications
Imaging
Test and Measurement
Passive Filter Replacement
3 Description
The TPS7A3501 is a positive voltage, low-noise
(3.8-µVRMS) power filter capable of sourcing a 1-A
load suitable for quiet supply solutions. Power filters,
such as the TPS7A3501, provide voltage regulation
across the input and output terminals with high
efficiency (low insertion loss), and power-supply
rejection. The device is ideally suited as a noise filter
for 3.3-V, 2.5-V, and 1.8-V supplies at up to 1 A.
The input-to-output voltage regulation is also userprogrammable, from 200 mV to 500 mV, with a single
external resistor. If no resistor is used, the
TPS7A3501 provides 330 mV of input-to-output
voltage regulation. The device is stable with 10-µF
input and output ceramic capacitors and a 10-nF
noise-reduction ceramic capacitor.
The TPS7A3501 is fully specified over a wide
temperature of –40°C to 125°C. The device is offered
in a low thermal resistance, 2-mm × 2-mm, WSON-6
package. Unlike passive filters, the TPS7A3501
provides thermal and current protection for itself and
surrounding circuitry.
Device Information(1)
PART NUMBER
TPS7A3501
PACKAGE
WSON (6)
BODY SIZE (NOM)
2.00 mm × 2.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Typical Application Circuit
(VIN – VOUT) = 300 mV
VIN = 3.6 V
+
IN
(Optional)
VOUT = 3.3 V
COUT = 10 µF
CIN = 10 µF
RNR
OUT
–
TPS7A3501
EN
SENSE
NR
GND
Load
CNR = 1 µF
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.
TPS7A3501
SBVS228B – JULY 2013 – REVISED MARCH 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
4
5
6.1
6.2
6.3
6.4
6.5
6.6
5
5
5
5
6
7
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 11
7.1
7.2
7.3
7.4
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
11
11
12
13
8
Application and Implementation ........................ 15
8.1 Application Information............................................ 15
8.2 Typical Application ................................................. 15
8.3 Do's and Don'ts ....................................................... 18
9 Power Supply Recommendations...................... 18
10 Layout................................................................... 19
10.1
10.2
10.3
10.4
Layout Guidelines .................................................
Layout Example ....................................................
Power Dissipation .................................................
Estimating Junction Temperature .........................
19
19
19
20
11 Device and Documentation Support ................. 21
11.1
11.2
11.3
11.4
11.5
Device Support......................................................
Documentation Support .......................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
21
21
21
21
21
12 Mechanical, Packaging, and Orderable
Information ........................................................... 21
4 Revision History
Changes from Revision A (October 2013) to Revision B
Page
•
Added ESD Ratings 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
•
Changed "free-air temperature" to "junction temperature" in Absolute Maximum Ratings condition statement ................... 5
•
Changed Figure 14 to Figure 18: collected new data ............................................................................................................ 8
Changes from Original (July 2013) to Revision A
Page
•
Changed document status to Production Data....................................................................................................................... 1
•
Changed document title.......................................................................................................................................................... 1
•
Deleted second sub-bullet from first Features bullet .............................................................................................................. 1
•
Changed sub-bullets in Power-Supply Rejection Ratio and Low-Noise Output Features bullets .......................................... 1
•
Changed Output Current, Transient Response, Ceramic Capacitors, and Package Features bullets .................................. 1
•
Deleted Input Voltage Range Features bullet ........................................................................................................................ 1
•
Added Output Voltage Range Features bullet........................................................................................................................ 1
•
Added 4th to 7th Applications bullets ..................................................................................................................................... 1
•
Changed 1st and 3rd paragraphs of Description section ....................................................................................................... 1
•
Changed voltage regulation value in second Description paragraph ..................................................................................... 1
•
Added changes to Typical Application Circuit ........................................................................................................................ 1
•
Changed descriptions of IN, NR, OUT, and PowerPAD pins in Pin Functions table ............................................................. 4
•
Added PowerPAD row to Pin Functions table ........................................................................................................................ 4
•
Changed associated pins of Voltage parameter in Absolute Maximum Ratings table........................................................... 5
•
Changed TJ Temperature range parameter minimum specification in Absolute Maximum Ratings table ............................. 5
•
Changed conditions of Electrical Characteristics table .......................................................................................................... 6
•
Changed VIN and VOUT parameter maximum specifications in Electrical Characteristics table.............................................. 6
•
Added VUVLO(in) parameter to Electrical Characteristics table ................................................................................................. 6
•
Changed VIN – VOUT voltage range, Vn, and Tsd parameters in Electrical Characteristics table............................................. 6
2
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•
Changed ICL and IEN parameter specifications in Electrical Characteristics table .................................................................. 6
•
Changed IGND parameter typical specification in Electrical Characteristics table ................................................................... 6
•
Changed ISHDN test conditions and parameter specifications in Electrical Characteristics table............................................ 6
•
Changed VEN(HI) parameter minimum specification in Electrical Characteristics table ........................................................... 6
•
Changed Typical Characteristics section ............................................................................................................................... 7
•
Added Functional Block Diagram ......................................................................................................................................... 11
•
Changed Application Information section ............................................................................................................................. 15
•
Changed Board Layout Recommendations section ............................................................................................................. 19
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5 Pin Configuration and Functions
DRV Package
6-Pin WSON
Top View
IN
1
6
OUT
EN
2
5
SENSE
GND
3
4
NR
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
Enable pin. Driving EN high turns on the device (if driven low, EN turns off the device).
EN must not be left floating and can be connected to IN if not used.
EN
2
I
GND
3
—
IN
1
I
Input supply. A capacitor greater than or equal to 10 µF must be tied from this pin to ground
to assure stability. This configuration is especially important when long input traces or high
source impedances are encountered. TI recommends using X5R- or X7R-type dielectrics to
minimize the temperature variations inherent to capacitors.
Ground
NR
4
O
Noise-reduction pin. When a capacitor is connected from this pin to GND, RMS noise can be
reduced to very low levels. A capacitor greater than or equal to 10 nF must be tied from this
pin to ground to assure stability. TI recommends connecting a 1-µF capacitor from NR to
GND (as close to the device as possible) to maximize AC performance and minimize noise.
TI recommends using X5R- or X7R-type dielectrics to minimize the temperature variations
inherent to capacitors. In addition, when a resistor is connected from this pin to GND or IN,
the device input-to-output voltage can be programmed; see Feature Description for details.
OUT
6
O
Regulator output. A capacitor greater than or equal to 10 µF must be tied from this pin to
ground to assure stability. TI recommends using a X5R- or X7R-type dielectrics to minimize
the temperature variations inherent to capacitors.
PowerPAD™
—
—
Connect the PowerPAD to the ground plane for improved thermal performance.
SENSE
5
I
4
Control-loop error amplifier input. This pin must be connected to OUT.
TI recommends connecting SENSE at the point of load to maximize accuracy.
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6 Specifications
6.1 Absolute Maximum Ratings
over operating junction temperature range (unless otherwise noted). (1)
Voltage
Current
(2)
MAX
–0.3
7
OUT, SENSE
–0.3
VIN + 0.3 (2)
OUT
Temperature
(1)
MIN
IN, NR, EN
UNIT
V
Internally limited
Operating junction, TJ
–40
125
Storage, Tstg
–55
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Absolute maximum rating is VIN + 0.3 V or + 7 V, whichever is smaller.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1)
±1000
Charged device model (CDM), per JEDEC specification JESD22-C101,
all pins (2)
±250
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating junction temperature range (unless otherwise noted).
MIN
VIN
Input voltage
IOUT
Output current
TJ
Operating junction temperature
NOM
MAX
UNIT
1.71
5
0
1
V
A
–40
125
°C
6.4 Thermal Information
THERMAL METRIC (1)
DRV (WSON)
6 PINS
RθJA
Junction-to-ambient thermal resistance
66.9
RθJC(top)
Junction-to-case (top) thermal resistance
86.5
RθJB
Junction-to-board thermal resistance
36.4
ψJT
Junction-to-top characterization parameter
1.8
ψJB
Junction-to-board characterization parameter
36.6
RθJC(bot)
Junction-to-case (bottom) thermal resistance
7.3
(1)
UNIT
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
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6.5 Electrical Characteristics
At TJ = –40°C to 125°C, VIN = 3.6 V, RNR = ∞ (not connected), IOUT = 10 mA, VEN = VIN, and CIN = COUT = 10 µF, unless
otherwise noted.
PARAMETER
VIN
Input voltage range
VUVLO(in)
Input supply UVLO
VOUT
Output voltage range
VIN – VOUT voltage range
TEST CONDITIONS
VIN increasing
kΩ
1.4
1.8
2.4
EN pin input current
VEN = VIN
ISHUTDOWN
Shutdown current (IGND)
VEN ≤ 0.3 V
(1)
(2)
6
mV
210
GND pin current
Thermal shutdown junction
temperature
V
500
170
IEN
Tsd
4.5
200
110
(2)
IGND
EN pin input high (enable)
1.21
RNR_INTERNAL (1)
VOUT = 0.85 × VOUT(nom)
VEN(HI)
V
mV
mV
Output current limit
EN pin input low (disable)
V
363
ICL
VEN(LO)
1.7
200
UNIT
330
10 mA ≤ IOUT ≤ 1 A
Output noise voltage
5
297
INR_INTERNAL
Vn
MAX
VOUT(nom) = VIN – 330 mV, IOUT ≤ 1 A,
1.71 V ≤ VIN ≤ 4.83 V
Load regulation
Power-supply rejection ratio
TYP
1.5
VIN hysteresis
∆VOUT(∆IOUT)
PSRR
MIN
1.71
10
µA
µV/mA
1.1
A
2.25
5
1
50
nA
0.01
3
µA
f = 10 kHz, CNR = 1 µF, IOUT = 0.5 A
55
f = 100 kHz, CNR = 1 µF, IOUT = 0.5 A
40
f = 1 MHz, CNR = 1 µF, IOUT = 0.5 A
42
BW = 10 Hz to 100 kHz, CNR = 1 µF, IOUT = 1 A
3.8
BW = 100 Hz to 100 kHz, CNR = 1 µF,
IOUT = 1 A
3.62
BW = 10 Hz to 1 MHz, CNR = 1 µF, IOUT = 1 A
12.1
dB
µVRMS
0.4
1.1
mA
V
V
Shutdown, temperature increasing
165
Shutdown, temperature hysteresis
20
°C
RNR_INTERNAL refers to the internal resistor used to set (VIN – VOUT) for the device when no external RNR is used. See Adjustable Voltage
Drop and Typical Application Circuit for details.
INR_INTERNAL refers to the internal current source used to set (VIN – VOUT) for the device when no external RNR is used. See Adjustable
Voltage Drop and Typical Application Circuit for details.
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6.6 Typical Characteristics
At VIN = 3.6 V, RNR = ∞ (not connected), IOUT = 10 mA, VEN = VIN, COUT = 10 µF, CIN = 10 µF, and CNR = 0.1 µF, unless
otherwise noted.
0.345
-40C
+105C
0C
+125C
0.322
+25C
0C
+125C
+25C
0.321
VIN - VOUT (V)
0.34
VIN - VOUT (V)
-40C
+105C
0.335
0.33
0.325
0.32
0.319
0.318
0.317
IOUT = 1 A
0.32
0.316
1.8
2.2
2.6
3
3.4
3.8
4.2
4.6
Input Voltage (V)
5
1.8
2.2
-40C
+105C
3.4
3.8
4.2
4.6
5
C002
Figure 2. Line Regulation
0C
+125C
0.6
+25C
0.34
0.5
¨9 P9
0.335
VIN - VOUT (V)
VIN - VOUT (V)
3
Input Voltage (V)
Figure 1. Line Regulation
0.345
2.6
C001
0.33
0.325
¨9 P9
0.4
¨9 P9
0.3
0.32
0.2
0.315
0.1
IOUT = 100 mA
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Output Current (A)
1
±40 ±25 ±10
-40C
+105C
3
0C
+125C
35
50
65
80
95
110 125
C004
Figure 4. VDELTA vs Temperature
4.5
+25C
-40C
+105C
0C
+125C
+25C
4
2.75
3.5
IGND (mA)
IGND (mA)
20
Temperature (C)
Figure 3. Load Regulation
3.25
5
C003
2.5
2.25
3
2.5
2
2
1.75
1.5
1.5
1.8
2.2
2.6
3
3.4
3.8
4.2
4.6
Input Voltage (V)
5
0
0.1
Figure 5. Ground Current vs Input Voltage
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Output Current (A)
C005
1
C006
Figure 6. Ground Current vs Output Current
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Typical Characteristics (continued)
At VIN = 3.6 V, RNR = ∞ (not connected), IOUT = 10 mA, VEN = VIN, COUT = 10 µF, CIN = 10 µF, and CNR = 0.1 µF, unless
otherwise noted.
1000
-40C
+105C
900
0C
+125C
800
2
+25C
-40C
+105C
0C
+125C
+25C
1.9
VEN = 0 V
600
ICL (A)
ISHDN (nA)
700
500
1.8
1.7
400
300
1.6
200
VOUT = 90% x VOUT(NOM)
100
1.5
0
1.8
2.1
2.4
2.7
3
3.3
1.8
3.6
Input Voltage (V)
2.1
2.4
2.7
3
3.3
3.6
Input Voltage (V)
C007
C008
Figure 8. Current Limit vs Input Voltage
Figure 7. Shutdown Current vs Input Voltage
100
3.5
Iout
OUT = 100 mA
90
3
Iout
OUT = 500 mA
Iout
OUT = 1 A
70
PSRR (dB)
Output Voltage (V)
80
2.5
2
1.5
60
50
40
30
1
20
0.5
10
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Iout (A)
1.8
10
2
¨9 P9
¨9 P9
100
¨9 P9
90
80
80
70
70
60
50
40
20
10k
Frequency (Hz)
100k
Cnr
NR = 10 nF
10
CIN = 1 F, Iout = 500 mA
1k
C010
10M
10
100
1k
10k
Frequency (Hz)
C010
Figure 11. Power-Supply Rejection Ratio vs Frequency
Cnr
NR = 100 nF
Cnr
NR = 1 uF
CIN = 1 F, Iout = 500 mA
0
1M
10M
40
30
100
1M
50
20
10
100k
60
30
0
10k
Figure 10. Power-Supply Rejection Ratio vs Frequency
90
10
1k
Frequency (Hz)
PSRR (dB)
PSRR (dB)
100
100
C009
Figure 9. Foldback Current Limit
8
CIN = 1 F, CNR = 1 µF
0
100k
1M
10M
C010
Figure 12. Power-Supply Rejection Ratio vs Frequency
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Typical Characteristics (continued)
At VIN = 3.6 V, RNR = ∞ (not connected), IOUT = 10 mA, VEN = VIN, COUT = 10 µF, CIN = 10 µF, and CNR = 0.1 µF, unless
otherwise noted.
10
RMS Noise
(BW 100Hz-100kHz)
Cnr
Vrms
1 uF
3.6
100 nF
4.2
10 nF
20.7
1RLVH 9¥+]
1
VIN = 3.6 V, IOUT = 10 mA → 1 A → 10 mA
CIN = COUT = 10 mF, CNR = 10 nF
Slew Rate = 1 A/ms
I OUT (1 A/div)
0.1
0.01
VOUT (50 mV/div)
Cnr
NR = 10 nF
Cnr
NR = 100 nF
Cnr
NR = 1 uF
0.001
10
100
1k
IOUT = 1 A
10k
100k
1M
Time (50 ms/div)
10M
Frequency (Hz)
C010
Figure 14. Load Transient Response
Figure 13. Spectral Noise Density vs Frequency
VIN = 1.7 V → 4.8 V → 1.7 V, IOUT = 500 mA
CIN = COUT = 10 mF, CNR = 10 mF, Slew Rate = 1 A/ms
VIN = 3.6 V, IOUT = 10 mA → 1 A → 10 mA
CIN = COUT = 10 mF, CNR = 1 mF
Slew Rate = 1 A/ms
VIN (2 V/div)
I OUT (1 A/div)
VOUT (50 mV/div)
VOUT (2 V/div)
Time (50 ms/div)
Time (10 ms/div)
Figure 15. Load Transient Response
Figure 16. Line Transient Response
VIN = 1.7 V → 4.8 V → 1.7 V, IOUT = 500 mA
CIN = COUT = 10 mF, CNR = 1 mF, Slew Rate = 1 A/ms
VIN (2 V/div)
VIN (2 V/div)
VOUT (2 V/div)
VOUT (2 V/div)
Time (10 ms/div)
VIN = VEN = 0 V → 3.6 V
IOUT = 1 A
CIN = COUT = 10 mF
CNR = 10 nF
Time (1 ms/div)
Figure 17. Line Transient Response
Figure 18. Start-up
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Typical Characteristics (continued)
At VIN = 3.6 V, RNR = ∞ (not connected), IOUT = 10 mA, VEN = VIN, COUT = 10 µF, CIN = 10 µF, and CNR = 0.1 µF, unless
otherwise noted.
VIN (2 V/div)
VIN = VEN = 0 V → 3.6 V
IOUT = 1 A
CIN = COUT = 10 mF
CNR = 1 mF
VOUT (2 V/div)
Time (1 ms/div)
Figure 19. Start-up
10
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7 Detailed Description
7.1 Overview
The TPS7A3501 is a positive-voltage, low-noise (3.8-µVRMS) power filter capable of sourcing a 1-A load. Power
filters such as the TPS7A3501 provide voltage regulation across the input and output terminals with high
accuracy and power-supply rejection ratio. The device is ideally suited as a noise filter for 4.5-V, 3.3-V, and 1.8-V
supplies up to 1-A loads.
The input-to-output voltage drop is also user-programmable, from 200 mV up to 500 mV, with an external
resistor. If no resistor is used, the TPS7A3501 provides 330 mV of input-to-output voltage regulation.
The TPS7A3501 is stable with 10-µF ceramic input and output capacitors and a 10-nF ceramic noise-reduction
capacitor. The device is fully specified over a wide temperature range of –40°C to 125°C and is offered in a low
thermal resistance, 2-mm × 2-mm, 6-pin WSON package.
7.2 Functional Block Diagram
VIN = 3.6 V
IN
CIN = 10 µF
VEN = 3.6 V
Charge Pump
EN
NR
+
OUT
(Optional)
RNR
VOUT = VIN – 300 mV = 3.3 V
–
CNR
1 mF
SENSE
COUT = 10 µF
GND
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7.3 Feature Description
7.3.1 Power Filter Operation
A power filter is very similar to a low-dropout (LDO) regulator, except that instead of regulating output voltage
relative to ground, the power filter regulates output voltage relative to VIN. In other words, a power filter maintains
a fixed ΔV from input to output. The device is optimized for high PSRR with a low VIN-to-VOUT delta, leading to a
lower power dissipation than standard LDOs. Unlike a standard LDO, the bandgap and noise associated with the
device are never gained up, resulting in low output noise regardless of VOUT. The external noise capacitor on the
power filter lets the user set the frequency at which the power filter starts to reject noise from the input. Table 1
summarizes the differences between a power filter and a high-performance LDO.
Table 1. Power Filter vs LDO Characteristics
PARAMETER
POWER FILTER
Voltage regulation
Regulates input-to-output delta. Voltage delta can be
set from 0.2 V to 0.5 V. Relies on the upstream power
rail to set the output voltage.
Regulates the output voltage referenced to ground.
Outputs any output voltage within the output voltage
range (limited by power dissipation).
PSRR
High PSRR at typical switching frequencies of DC-DC
converters with lower power dissipation. Lower PSRR
at low frequencies.
High PSRR over broad bandwidth. Effective rejection
of low-frequency noise and switching noise from DCDC.
Noise
Lower noise, 3.8 µV. Noise is not gained up when
VOUT increases.
Low noise (typically in the range of 5 µVRMS to
20 µVRMS). Noise is gained up when VOUT increases.
High PSRR can be achieved with only 330 mV from
VIN to VOUT.
Typically requires 750 mV to 1 V of VIN-to-VOUT delta
to achieve high PSRR.
Power dissipation
LDO
7.3.2 Minimum Load
The device is stable without an output load.
7.3.3 Shutdown
The enable pin (EN) is active high and compatible with standard and low-voltage TTL-CMOS levels. The enable
pin voltage level is independent of input voltage and can be biased to a higher value than VIN as long as EN is
within the maximum specification. When shutdown capability is not required, EN can be connected to IN.
7.3.4 Internal Current Limit
The device has an internal foldback current limit that helps protect the power filter during fault conditions. The
current supplied by the device is gradually reduced when the output voltage decreases. When the output is
shorted to GND, the LDO supplies a typical current of 550 mA. When in current limit, the output voltage is not
regulated and VOUT = IOUT × RLOAD. For reliable operation, do not operate the device in current limit for extended
periods of time.
Because of the nature of the foldback current limit circuitry, if OUT is forced below 0 V before EN goes high, the
device may not start up. To ensure proper start-up in applications that have both a positive and negative voltage
rail, extra care must be taken to ensure that OUT is greater than or equal to 0 V. There are several ways to help
ensure proper start-up for dual-rail applications:
• Enable the device before the negative rail and disable the device after the negative rail.
• Delaying the EN voltage with respect to IN voltage allows the internal pulldown resistor to discharge any
residual voltage at OUT.
• If a faster discharge rate is required, or if EN is tied directly to IN, an external resistor from OUT to GND can
be used.
7.3.5 Reverse Current
The TPS7A3501 has a built-in body diode that conducts current when the voltage at OUT exceeds the voltage at
IN. This current is not internally limited, so if reverse voltage conditions are anticipated, external limiting is
required.
If there are potential situations where reverse current is expected, place a diode from OUT to IN, as shown in
Figure 20.
12
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VIN
VOUT
IN
OUT
Device
EN
NR
Load
SENSE
GND
Figure 20. Reverse Current Protection Schematic
7.3.6 Undervoltage Lockout (UVLO)
The device uses an undervoltage lockout circuit to keep the output shut off until the internal circuitry is operating
properly, ensuring a well-controlled start-up.
7.3.7 Thermal Protection
Thermal protection disables the output when the junction temperature rises to approximately 160°C, allowing the
device to cool. When the junction temperature cools to approximately 140°C, the output circuitry is again
enabled. Depending on power dissipation, thermal resistance, and ambient temperature, the thermal protection
circuit may cycle on and off. This cycling limits device power dissipation, thus protecting the device from damage
resulting from overheating.
Any activation of the thermal protection circuit indicates excessive power dissipation or inadequate thermal
dissipation on the PCB. For reliable operation, limit junction temperature to 125°C (maximum). To estimate the
margin of safety in a complete design, increase the ambient temperature until the thermal protection is triggered
using worst-case loads and signal conditions. For good reliability, thermal protection should trigger at least 35°C
above the maximum expected ambient condition of the application. This configuration produces a worst-case
junction temperature of 125°C at the highest-expected ambient temperature and worst-case load.
The device internal protection circuitry is designed to protect against overload conditions. This circuitry is not
intended to replace proper heat-sinking or thermal dissipation on the PCB. Continuously running the device into
thermal shutdown degrades device reliability.
7.4 Device Functional Modes
Table 2 provides a quick comparison between the normal, dropout, and disabled modes of operation.
Table 2. Device Functional Mode Comparison
PARAMETER
OPERATING
MODE
VIN
EN
IOUT
TJ
Normal
1.71 ≤ VIN ≤ 5
VEN > VEN(HI)
IOUT < ICL
TJ < Tsd
Disabled
—
VEN < VEN(LO)
—
TJ > Tsd
7.4.1 Normal Operation
The device functions as a fixed voltage drop filter under the following conditions:
• The input voltage is within the specified operating range of 1.71 V to 5 V.
• The enable voltage has previously exceeded the enable rising threshold voltage and not yet decreased below
the enable falling threshold.
• The output current is less than the current limit (IOUT < ICL).
• The device junction temperature is less than the thermal shutdown temperature (TJ < Tsd).
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7.4.2 Disabled
The device is disabled under the following conditions:
• The enable voltage is less than the enable falling threshold voltage or has not yet exceeded the enable rising
threshold.
• The device junction temperature is greater than the thermal shutdown temperature (TJ > Tsd).
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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
The TPS7A3501 is well-suited for use as a filter for switching power supplies. The high PSRR of the device
significantly reduces the ripple caused by the switching frequency as well as the subsequent harmonic
frequencies. Figure 21 shows the basic circuit connections for the TPS7A3501. The IN pin should be connected
to a well-regulated power source, typically a switching power supply.
+
VIN
IN
OUT
±
VOUT
Optional(1)
Device
(1)
Decreases
'V
EN
Load
SENSE
NR
GND
Increases
'V
Refer to Table 4.
Figure 21. Basic Circuit Connections
8.2 Typical Application
Figure 22 shows a schematic for filtering the output of a switching regulator using the TPS7A3501 to power an
analog-to-digital converter (ADC).
PVIN
VIN
TPS54620
BOOT
EN
IN
PH
OUT
CIN
PWRGD
COUT
Device
SS/TR
RT/CLK
COMP
VSENSE
GND
EN
ADC
SENSE
NR
GND
CNR
Exposed
Thermal
Pad
Figure 22. Typical Application Schematic
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Typical Application (continued)
8.2.1 Design Requirements
Table 3 shows the design requirements.
Table 3. Design Requirements
PARAMETER
DESIGN REQUIREMENT
Input voltage
3.63 V
Output voltage
3.3 V
100-Hz to 100-kHz RMS noise
< 4 µVRMS
Maximum output current
700 mA
8.2.2 Detailed Design Procedure
Select the input and output capacitors to be at least 10 µF for stability. Select a value for RNR to give the desired
voltage drop. For this example of a 330-mV voltage drop, no external resistor on the NR pin is required. Pick a
value for CNR greater than 10 nF, but large enough to provide the required noise performance. Refer to Table 5
for guidelines on selecting CNR for a desired RMS noise target. For this example, to achieve an RMS noise (100
Hz to 100 kHz) less than 4 µVRMS, the noise reduction capacitor must be at least 1 µF.
8.2.2.1 Adjustable Voltage Drop
In the TPS7A3501, the nominal voltage drop (ΔV) from IN to OUT is 330 mV. ΔV can be adjusted from this
nominal setting with an external resistor. By connecting a resistor from the NR pin to IN, ΔV can be decreased to
as low as 200 mV. By connecting a resistor from the NR pin to GND, ΔV can be increased to as high as 500 mV.
The ability to change ΔV allows for the creation of standard voltage rails from higher voltage rails (for example,
2.5 V from 3 V, 1.5 V from 1.8 V, and so forth).
By connecting a resistor from the NR pin to IN, ΔV can be decreased to as low as 200 mV. Use Equation 1 to
determine the size of the resistor required to set ΔV.
R = ΔV / (0.33 – ΔV) × 150,000 Ω
(1)
By connecting a resistor from the NR pin to GND, ΔV can be increased to as high as 500 mV. Use Equation 2 to
determine the size of the resistor required to set ΔV.
R = VOUT / (ΔV – 0.33) × 150,000 Ω
(2)
Table 4 lists the standard external resistor values required for different input-to-output voltage drops.
Table 4. Common Input-to-Output Voltage Drops
ΔV (mV)
VOUT
200
330
400
500
R TO VIN
R TO GND
Any
240 kΩ
Do not install
Any
Do not install
Do not install
3.3 V
Do not install
6.8 MΩ
2.5 V
Do not install
5.1 MΩ
1.8 V
Do not install
3.9 MΩ
3.3 V
Do not install
3 MΩ
2.5 V
Do not install
2.2 MΩ
1.8 V
Do not install
1.6 MΩ
8.2.2.2 Input and Output Capacitor Requirements
Ceramic 10-µF or larger input and output capacitors are required to assure proper device operation. This
capacitor counteracts reactive source impedances, improving supply transient response and decreasing input
ripple. Higher-value capacitors may be used if large, fast slew rate load transients are anticipated, or if the device
is located several inches away from the power source. To assure correct device operation, there should be no
more than 100 µF of capacitance on the output of the device, including capacitance from downstream bypass
capacitors.
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TI recommends X5R- and X7R-type ceramic capacitors because these types of capacitors have minimal
variation in value and equivalent series resistance (ESR) overtemperature. Other types of capacitors, such as
electrolytic or tantalum, can make the device unstable.
8.2.2.3 Output Noise
A 10-nF, or higher, noise-reduction capacitor is required to assure stability. Using a 1-μF ceramic capacitor
minimizes output noise (see Figure 13). To assure correct device operation, a maximum capacitor of 2.2 µF can
be connected to NR.
8.2.2.4 Power-Supply Rejection Ratio (PSRR)
Unlike standard LDOs, the TPS7A3501 PSRR is significantly affected by the noise-reduction capacitor. The
larger the noise-reduction capacitor, the higher the PSRR is for frequencies below 10 kHz. Using a 1-μF ceramic
capacitor maximizes PSRR.
One of the most compelling features of the TPS7A3501 is its high PSRR capabilities. The rejection ratio for this
device is lower than standard LDOs at frequencies below 1 kHz but becomes higher at higher frequencies. For
better low-frequency PSRR performance, a larger noise-reduction capacitor can be used. TI recommends
connecting a 1-µF ceramic capacitor to NR to maximize PSRR (see Figure 12). A higher input-to-output voltage
difference also increases the device rejection ratio. Although the device maximizes rejection ratio at 500 mV,
high rejection ratio can still be achieved with as little as a 330-mV input-to-output voltage differential, unlike most
standard LDOs.
8.2.2.5 Start-up
Because adding a noise-reduction capacitor leads to the formation of an RC filter, start-up time and the rate at
which the device tracks VIN are increased. Thus, consider the tradeoff between start-up time, noise, and PSRR
when selecting a noise-reduction capacitor to use with the TPS7A3501. Use Equation 3 to calculate the typical
start-up time.
T_startup = 250,000 × CNR (s)
(3)
Table 5 shows the effect of various noise-reduction capacitors on RMS noise (with a 100-Hz to 100-kHz
bandwidth), PSRR (at 1 kHz), and start-up time.
Table 5. Effect of Various Filter Capacitors
FILTER CAPACITOR
RMS NOISE
(BW 100 Hz to 100 kHz)
PSRR
(at 1 kHz)
START-UP TIME
(EN to 90% of VOUT)
1 µF
3.62 µV
60 dB
250 ms
100 nF
4.21 µV
40 dB
25 ms
10 nF
20.70 µV
20 dB
3 ms
8.2.2.6 Transient Response
Increasing the size of the output capacitor reduces overshoot and undershoot magnitude during transients;
however this size increase also slows the recovery from these transients.
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8.2.3 Application Curves
10
100
¨9 P9
¨9 P9
RMS Noise
(BW 100Hz-100kHz)
Cnr
Vrms
1 uF
3.6
100 nF
4.2
10 nF
20.7
¨9 P9
90
80
1
1RLVH 9¥+]
PSRR (dB)
70
60
50
40
30
0.1
0.01
Cnr
NR = 10 nF
20
Cnr
NR = 100 nF
10
CIN = 1 F, Iout = 500 mA
0
10
100
1k
10k
100k
Cnr
NR = 1 uF
0.001
1M
Frequency (Hz)
10M
10
1k
10k
100k
1M
10M
Frequency (Hz)
C010
Figure 23. Power-Supply Rejection Ratio vs Frequency
100
IOUT = 1 A
C010
Figure 24. Spectral Noise Density vs Frequency
8.3 Do's and Don'ts
Place at least 10-μF ceramic capacitors on both the IN and OUT pins of the device, as close as possible to the
pins of the regulator.
Do not place the input or output capacitor more than 10 mm away from the regulator.
Connect a 10-nF or greater, low-equivalent series resistance (ESR) capacitor across the NR pin and GND of the
regulator. Larger capacitors provide lower noise performance.
Do not use a capacitor larger than 2.2 µF on the NR pin.
Do not exceed the absolute maximum ratings.
9 Power Supply Recommendations
For best performance, connect a low-output impedance power supply directly to the IN pin of the device.
Inductive impedances between the input supply and the IN pin create significant voltage excursions at the IN pin.
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10 Layout
10.1 Layout Guidelines
Input and output capacitors should be placed as close to the device pins as possible. TI recommends that all
components be on the same side of the printed-circuit-board (PCB) as the device. Using long, thin traces or vias
to connect the device to external components is highly discouraged because this practice leads to parasitic
inductances, which in turn degrade noise, PSRR, and transient response. For an example layout, refer to the
TPS7A3501EVM-547 Evaluation Module User Guide ( SLVU921).
10.2 Layout Example
GND PLANE
COUT
CIN
TPS7A3501
VIN
IN
1
6
OUT
EN
2
5
SENSE
GND
3
4
NR
VOUT
GND PLANE
CNR
Figure 25. PCB Layout Example (DRV Package)
10.3 Power Dissipation
Knowing the device power dissipation and proper sizing of the thermal plane connected to the tab or pad is
critical to avoiding thermal shutdown and ensuring reliable operation. Device power dissipation depends on input
voltage and load conditions and can be calculated with Equation 4:
PD = (VIN – VOUT) × IOUT
(4)
Power dissipation can be minimized and greater efficiency can be achieved by using the lowest available voltage
drop option of 200 mV. However, keep in mind that higher voltage drops result in better PSRR performance.
On the WSON (DRV) package, the primary conduction path for heat is through the exposed power pad to the
PCB. To ensure the device does not overheat, connect the pad to ground with an appropriate amount of copper
PCB area through vias.
The maximum power dissipation determines the maximum allowable junction temperature (TJ) for the device.
Power dissipation and junction temperature are most often related by the junction-to-ambient thermal resistance
(θJA) of the combined PCB and device package and the temperature of the ambient air (TA), according to
Equation 5:
TJ = TA + (θJA × PD)
(5)
Unfortunately, this thermal resistance (θJA) is highly dependent on the heat-spreading capability of the particular
PCB design, and therefore varies according to the total copper area, copper weight, and location of the planes.
The θJA recorded in the table is determined by the JEDEC standard for PCB and copper-spreading area and is to
be used only as a relative measure of package thermal performance. For a well-designed thermal layout, θJA is
actually the sum of the package junction-to-case (bottom) thermal resistance (θJCbot) plus the thermal resistance
contribution by the PCB copper.
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10.4 Estimating Junction Temperature
The JEDEC standard now recommends the use of psi (Ψ) thermal metrics to estimate the junction temperatures
of the power filter on a typical PCB board application. These metrics are not strictly speaking thermal
resistances, but rather offer practical and relative means of estimating junction temperatures. These psi metrics
are determined to be significantly independent of copper-spreading area. The key thermal metrics (ΨJT and ΨJB)
are given in the table and are used in accordance with Equation 6.
YJT: TJ = TT + YJT ´ PD
YJB: TJ = TB + YJB ´ PD
where:
•
•
•
20
PD is the power dissipated as explained in Equation 4,
TT is the temperature at the center-top of the device package, and
TB is the PCB surface temperature measured 1 mm from the device package and centered on the package
edge.
(6)
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11 Device and Documentation Support
11.1 Device Support
11.1.1 Development Support
11.1.1.1 Evaluation Modules
An evaluation module (EVM) is available to assist in the initial circuit performance evaluation using the
TPS7A3501. The TPS7A3501EVM-547 evaluation module (and related user guide) can be requested at the
Texas Instruments website through the product folder or purchased directly from the TI eStore.
11.1.1.2 Spice Models
Computer simulation of circuit performance using SPICE is often useful when analyzing the performance of
analog circuits and systems. A SPICE model for the TPS7A3501 is available through the product folder under
Tools & Software.
11.2 Documentation Support
11.2.1 Related Documentation
•
TPS7A3501EVM-547 User's Guide, SLVU921.
11.3 Trademarks
PowerPAD is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
11.5 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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11-Aug-2022
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)
Samples
(4/5)
(6)
TPS7A3501DRVR
ACTIVE
WSON
DRV
6
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
SIQ
Samples
TPS7A3501DRVT
ACTIVE
WSON
DRV
6
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
SIQ
Samples
(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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