SGLS176 − AUGUST 2003
D Controlled Baseline
D
D
D
D
D
D
D
D
− One Assembly/Test Site, One Fabrication
Site
Extended Temperature Performance of
−40°C to 125°C
Enhanced Diminishing Manufacturing
Sources (DMS) Support
Enhanced Product Change Notification
Qualification Pedigree†
Open Drain Power Good
500-mA Low-Dropout Voltage Regulator
Available in 1.5-V, 1.8-V, 2.5-V, 2.8-V, 3.3-V
Fixed Output and Adjustable Versions
Dropout Voltage to 169 mV (Typ) at 500 mA
(TPS77633)
† Component qualification in accordance with JEDEC and industry
standards to ensure reliable operation over an extended
temperature range. This includes, but is not limited to, Highly
Accelerated Stress Test (HAST) or biased 85/85, temperature
cycle, autoclave or unbiased HAST, electromigration, bond
intermetallic life, and mold compound life. Such qualification
testing should not be viewed as justifying use of this component
beyond specified performance and environmental limits.
D Ultralow 85 µA Typical Quiescent Current
D Fast Transient Response
D 2% Tolerance Over Specified Conditions for
D
D
Fixed-Output Versions
20-Pin TSSOP PowerPAD (PWP) Package
Thermal Shutdown Protection
PWP PACKAGE
(TOP VIEW)
GND/HSINK
GND/HSINK
GND
NC
EN
IN
IN
NC
GND/HSINK
GND/HSINK
1
20
2
19
3
18
4
17
5
16
6
15
7
14
8
13
9
12
10
11
GND/HSINK
GND/HSINK
NC
NC
PG
FB/NC
OUT
OUT
GND/HSINK
GND/HSINK
NC − No internal connection
description
The TPS776xx devices are designed to have a fast transient response and be stable with a 10-µF low ESR
capacitors. This combination provides high performance at a reasonable cost.
Because the PMOS device behaves as a low-value resistor, the dropout voltage is very low (typically 169 mV at an
output current of 500 mA for the TPS77633) and is directly proportional to the output current. Additionally, since the
PMOS pass element is a voltage-driven device, the quiescent current is very low and independent of output loading
(typically 85 µA over the full range of output current, 0 mA to 500 mA). These two key specifications yield a significant
improvement in operating life for battery-powered systems. This LDO family also features a sleep mode; applying
a TTL high signal to EN (enable) shuts down the regulator, reducing the quiescent current to 1 µA at TJ = 25°C.
Power good (PG) of the TPS776xx is an active high output, which can be used to implement a power-on reset or
a low-battery indicator.
The TPS776xx are offered in 1.5-V, 1.8-V, 2.5-V, 2.8 V, and 3.3-V fixed-voltage versions and in an adjustable version
(programmable over the range of 1.2 V to 5.5 V for TPS77601 option). Output voltage tolerance is specified as a
maximum of 2% over line, load, and temperature ranges. The TPS776xx family is available in 20 pin TSSOP
package.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PowerPAD is a trademark of Texas Instruments.
Copyright 2003, Texas Instruments Incorporated
!"#$%" & '(##)% $& "! *(+,'$%" -$%).
#"-('%& '"!"# %" &*)'!'$%"& *)# %/) %)#& "! )0$& &%#()%&
&%$-$#- 1$##$%2. #"-('%" *#"')&&3 -")& "% )')&&$#,2 ',(-)
%)&%3 "! $,, *$#$)%)#&.
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TPS77x33
DROPOUT VOLTAGE
vs
FREE-AIR TEMPERATURE
TPS77x33
LOAD TRANSIENT RESPONSE
∆ VO − Change in
Output Voltage − mV
103
102
IO = 500 mA
101
I O − Output Current − mA
VDO − Dropout Voltage − mV
Co = 10 µF
IO = 10 mA
100
10−1
IO = 0 mA
10−2
−60 −40 −20
0
20
40
60
Co = 2x47 µF
ESR = 1/2x100 mΩ
VO = 3.3 V
VI = 4.3 V
50
0
−50
500
80 100 120 140
0
0
20
40
60
TA − Free-Air Temperature − °C
80 100 120 140 160 180 200
t − Time − µs
ORDERING INFORMATION†
TA
−40°C
125°C
−40
C to 125
C
OUTPUT
VOLTAGE
(V TYP)
ORDERABLE
PART NUMBER
PACKAGE
TOP-SIDE
MARKING
3.3
TSSOP − PW
Tape and reel
TSSOP − PW
Tape and reel
TPS77633QPWPREP
TPS77628QPWPREP§
77633QE
2.8
2.5
TSSOP − PW
Tape and reel
TPS77625QPWPREP
77625QE
1.8
TSSOP − PW
Tape and reel
TPS77618QPWPREP
77618QE
1.5
TSSOP − PW
Tape and reel
TPS77615QPWPREP
77615QE
Adjustable‡
1.2 V to 5.5 V
TSSOP − PW
Tape and reel
TPS77601QPWPREP
77601QE
77628QE
† Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at
www.ti.com/sc/package.
‡ The TPS77601 is programmable using an external resistor divider (see application information).
§ TPS77628 is Product Preview.
VI
6
PG
IN
16
PG
7
IN
OUT
0.1 µF
5
OUT
EN
14
VO
13
+
GND
Co†
10 µF
3
† See application information section for capacitor selection details.
2
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SGLS176 − AUGUST 2003
Figure 1. Typical Application Configuration for Fixed Output Options
functional block diagram—adjustable version
IN
EN
PG
_
+
OUT
+
_
R1
Vref = 1.183 V
FB/NC
R2
GND
External to the device
functional block diagram—fixed-voltage version
IN
EN
PG
_
+
OUT
+
_
R1
Vref = 1.183 V
R2
GND
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SGLS176 − AUGUST 2003
Terminal Functions
TSSOP Package
TERMINAL
NAME
NO.
I/O
DESCRIPTION
EN
5
I
Enable input
FB/NC
15
I
Feedback input voltage for adjustable device (no connect for fixed options)
GND
GND/HSINK
3
Regulator ground
1, 2, 9, 10, 11,
12, 19, 20
Ground/heatsink
IN
6, 7
NC
4, 8, 17, 18
OUT
PG
4
I
Input voltage
No connect
13, 14
O
Regulated output voltage
16
O
PG output
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SGLS176 − AUGUST 2003
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)Ĕ
Input voltage range‡, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to 13.5 V
Voltage range at EN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to 16.5 V
Maximum PG voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.5 V
Peak output current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internally limited
Output voltage, VO (OUT, FB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See dissipation rating tables
Operating virtual junction temperature range, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −40°C to 125°C
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to 150°C
ESD rating, HBM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kV
† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied.
Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
‡ All voltage values are with respect to network terminal ground.
DISSIPATION RATING TABLE − FREE-AIR TEMPERATURES
PACKAGE
AIR FLOW
(CFM)
PWP§
PWP¶
TA < 25°C
POWER RATING
DERATING FACTOR
ABOVE TA = 25°C
TA = 70°C
POWER RATING
TA = 85°C
POWER RATING
0
2.9 W
23.5 mW/°C
1.9 W
1.5 W
300
4.3 W
34.6 mW/°C
2.8 W
2.2 W
0
3W
23.8 mW/°C
1.9 W
1.5 W
300
7.2 W
57.9 mW/°C
4.6 W
3.8 W
§ This parameter is measured with the recommended copper heat sink pattern on a 1-layer PCB, 5-in × 5-in PCB, 1 oz. copper, 2-in
× 2-in coverage (4 in2).
¶ This parameter is measured with the recommended copper heat sink pattern on a 8-layer PCB, 1.5-in × 2-in PCB, 1 oz. copper with
layers 1, 2, 4, 5, 7, and 8 at 5% coverage (0.9 in2) and layers 3 and 6 at 100% coverage (6 in2). For more information, refer to TI
technical brief SLMA002.
recommended operating conditions
MIN
Input voltage, VI#
Output voltage range, VO
Output current, IO (see Note 1)
MAX
UNIT
2.7
10
V
1.2
5.5
V
0
500
mA
Operating virtual junction temperature, TJ (see Note 1)
−40
125
°C
# To calculate the minimum input voltage for your maximum output current, use the following equation: VI(min) = VO(max) + VDO(max load).
NOTE 1: Continuous current and operating junction temperature are limited by internal protection circuitry, but it is not recommended that the device
operate under conditions beyond those specified in this table for extended periods of time.
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SGLS176 − AUGUST 2003
electrical characteristics over recommended operating free-air temperature range,
VI = VO(typ) + 1 V, IO = 1 mA, EN = 0 V, Co = 10 µF (unless otherwise noted)
PARAMETER
TEST CONDITIONS
TPS77601
Output voltage (10 µA to 500 mA load)
(see Note 2)
1.2 V ≤ VO ≤ 5.5 V,
1.2 V ≤ VO ≤ 5.5 V,
MIN
TJ = 25°C
TJ = −40°C to 125°C
TPS77615
TJ = 25°C,
TJ = −40°C to 125°C,
2.7 V < VIN < 10 V
TPS77618
TJ = 25°C,
TJ = −40°C to 125°C,
2.8 V < VIN < 10 V
TPS77625
TJ = 25°C,
TJ = −40°C to 125°C,
3.5 V < VIN < 10 V
TPS77628
TJ = 25°C,
TJ = −40°C to 125°C,
TPS77633
TJ = 25°C,
TJ = −40°C to 125°C,
2.7 V < VIN < 10 V
2.8 V < VIN < 10 V
0.98VO
1.470
3.234
Output current limit
VO = 0 V
TPS77601
3.366
85
125
TJ = 25°C, 2.7 V < VI < 10 V
TJ = −40°C to 125°C
2.7 V < VI < 10 V
EN = VI,
FB input current
2.856
%/V
3
mV
53
µVrms
1
µA
2
V
0.9
Co = 10 µF, TJ = 25°C
NOTES: 2. Minimum IN operating voltage is 2.7 V or VO(typ) + 1 V, whichever is greater. Maximum IN voltage 10V.
3. If VO ≤ 1.8 V then VImin = 2.7 V, VImax = 10 V:
f = 1 KHz,
Line Reg. (mV) + ǒ%ńVǓ
V
O
100
If VO ≥ 2.5 V then VImin = VO + 1 V, VImax = 10 V:
V
Line Reg. (mV) + ǒ%ńVǓ
ǒVImax * 2.7 VǓ
O
1000
ǒVImax * ǒVO ) 1 VǓǓ
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100
• DALLAS, TEXAS 75265
1000
µA
nA
1.7
Power supply ripple rejection (see Note 2)
A
°C
Low level enable input voltage
6
2.4
150
10
FB = 1.5 V
High level enable input voltage
µA
A
0.01
1.7
EN = VI,
V
3.3
Thermal shutdown junction temperature
Standby current
2.550
2.8
Load regulation
BW = 200 Hz to 100 kHz, IC = 500 mA
Co = 10 µF,
TJ = 25°C
1.836
2.5
4.3 V < VIN < 10 V
Output noise voltage (TPS77x18)
V
1.8
2.744
VO + 1 V < VI ≤ 10 V, TJ = 25°C
UNIT
1.530
1.764
3.8 V < VIN < 10 V
4.3 V < VIN < 10 V
Output voltage line regulation (∆VO/VO)
(see Notes 2 and 3)
1.02VO
1.5
2.450
10 µA < IO < 500 mA, TJ = 25°C
IO = 500 mA,
TJ = −40°C to 125°C
MAX
VO
3.5 V < VIN < 10 V
3.8 V < VIN < 10 V
Quiescent current (GND current)
EN = 0V, (see Note 2)
TYP
60
V
dB
SGLS176 − AUGUST 2003
electrical characteristics over recommended operating free-air temperature range,
VI = VO(typ) + 1 V, IO = 1 mA, EN = 0 V, Co = 10 µF (unless otherwise noted) (continued)
PARAMETER
TEST CONDITIONS
Trip threshold voltage
IO(PG) = 300 µA
VO decreasing
Hysteresis voltage
Measured at VO
Output low voltage
VI = 2.7 V,
V(PG) = 5 V
Minimum input voltage for valid PG
PG
Leakage current
Input current (EN)
MIN
TYP
92
UNIT
V
98
%VO
%VO
0.4
V
1
µA
0.5
IO(PG) = 1 mA
0.15
EN = 0 V
−1
EN = VI
−1
0
1
µA
A
1
IO = 500 mA,
IO = 500 mA,
TJ = 25°C
TJ = −40°C to 125°C
285
TPS77628
TPS77633
IO = 500 mA,
IO = 500 mA,
TJ = 25°C
TJ = −40°C to 125°C
169
Dropout voltage (see Note 4)
MAX
1.1
410
mV
287
NOTE 4: IN voltage equals VO(typ) − 100 mV; TPS77615, TPS77618, and TPS77625 dropout voltage limited by input voltage range limitations (i.e.,
TPS77633 input voltage needs to drop to 3.2 V for purpose of this test).
TY
PICAL CHARACTERISTICS
Table of Graphs
FIGURE
VO
Output voltage
vs Output current
2, 3, 4
vs Free-air temperature
5, 6, 7
Ground current
vs Free-air temperature
8
Power supply ripple rejection
vs Frequency
9
Output spectral noise density
vs Frequency
10
Zo
Output impedance
vs Frequency
11
VDO
Dropout voltage
Input voltage (min)
VO
vs Input voltage
12
vs Free-air temperature
13
vs Output voltage
14
Line transient response
15, 17
Load transient response
16, 18
Output voltage
vs Time
Equivalent series resistance (ESR)
vs Output current
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19
21 − 24
7
SGLS176 − AUGUST 2003
TYPICAL CHARACTERISTICS
TPS77x33
TPS77x15
OUTPUT VOLTAGE
vs
OUTPUT CURRENT
OUTPUT VOLTAGE
vs
OUTPUT CURRENT
1.4985
3.2835
VI = 4.3 V
TA = 25°C
3.2830
VI = 2.7 V
TA = 25°C
1.4980
1.4975
VO − Output Voltage − V
VO − Output Voltage − V
3.2825
1.4970
3.2820
1.4965
3.2815
1.4960
3.2810
3.2805
1.4955
1.4950
3.2800
0
0.1
0.2
0.3
0.4
0
0.5
0.1
0.2
Figure 2
TPS77x25
TPS77x33
OUTPUT VOLTAGE
vs
OUTPUT CURRENT
OUTPUT VOLTAGE
vs
FREE-AIR TEMPERATURE
0.5
3.32
VI = 3.5 V
TA = 25°C
2.4955
VI = 4.3 V
3.31
VO − Output Voltage − V
2.4950
VO − Output Voltage − V
0.4
Figure 3
2.4960
2.4945
2.4940
2.4935
2.4930
3.30
3.29
IO = 500 mA
IO = 1 mA
3.28
3.27
3.26
2.4925
2.4920
0
0.1
0.2
0.3
0.4
0.5
3.25
−60 −40 −20
0
20
40
Figure 4
Figure 5
POST OFFICE BOX 655303
60
80
100 120 140
TA − Free-Air Temperature − °C
IO − Output Current − A
8
0.3
IO − Output Current − A
IO − Output Current − A
• DALLAS, TEXAS 75265
SGLS176 − AUGUST 2003
TYPICAL CHARACTERISTICS
TPS77x15
TPS77x25
OUTPUT VOLTAGE
vs
FREE-AIR TEMPERATURE
OUTPUT VOLTAGE
vs
FREE-AIR TEMPERATURE
1.515
2.515
VI = 3.5 V
VI = 2.7 V
2.510
VO − Output Voltage − V
VO − Output Voltage − V
1.510
1.505
1.500
IO = 500 mA
IO = 1 mA
1.495
1.490
2.505
2.500
IO = 500 mA
2.495
IO = 1 mA
2.490
2.485
1.485
−60 −40 −20
0
20
40
60
80
2.480
−60 −40
100 120 140
TA − Free-Air Temperature − °C
−20
Figure 6
TPS77xxx
40
60
80
100 120
TPS77x33
POWER SUPPLY RIPPLE REJECTION
vs
FREQUENCY
90
VI = 2.7 V
95
IO = 1 mA
85
IO = 500 mA
80
75
−60 −40 −20
0
20
40
60
80
100 120 140
PSRR − Power Supply Ripple Rejection − dB
100
Ground Current − µ A
20
Figure 7
GROUND CURRENT
vs
FREE-AIR TEMPERATURE
90
0
TA − Free-Air Temperature − °C
VI = 4.3 V
Co = 10 µF
TA = 25°C
80
70
60
50
40
30
20
10
0
−10
101
TA − Free-Air Temperature − °C
102
103
104
f − Frequency − Hz
105
106
Figure 9
Figure 8
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9
SGLS176 − AUGUST 2003
TYPICAL CHARACTERISTICS
TPS77x33
TPS77x33
OUTPUT SPECTRAL NOISE DENSITY
vs
FREQUENCY
OUTPUT IMPEDANCE
vs
FREQUENCY
100
VI = 4.3 V
Co = 10 µF
TA = 25°C
VI = 4.3 V
Co = 10 µF
TA = 25°C
Zo − Output Impedance − Ω
Output Spectral Noise Density − µV Hz
10−5
IO = 7 mA
10−6
IO = 500 mA
10−7
10−8
102
103
104
IO = 1 mA
10−1
IO = 500 mA
10−2
101
105
102
103
104
f − Frequency − kHz
f − Frequency − Hz
Figure 10
105
106
Figure 11
TPS77x33
TPS77x01
DROPOUT VOLTAGE
vs
FREE-AIR TEMPERATURE
DROPOUT VOLTAGE
vs
INPUT VOLTAGE
103
350
IO = 500 mA
Co = 10 µF
VDO − Dropout Voltage − mV
VDO − Dropout Voltage − mV
300
250
200
TA = 25°C
TA = 125°C
150
100
TA = −40°C
102
IO = 500 mA
101
IO = 10 mA
100
10−1
50
IO = 0 mA
0
2.5
3
4
3.5
VI − Input Voltage − V
4.5
5
10−2
−60 −40 −20
Figure 12
10
0
20
40
Figure 13
POST OFFICE BOX 655303
60
80 100 120 140
TA − Free-Air Temperature − °C
• DALLAS, TEXAS 75265
SGLS176 − AUGUST 2003
TYPICAL CHARACTERISTICS
INPUT VOLTAGE (MIN)
vs
OUTPUT VOLTAGE
TPS77x15
LINE TRANSIENT RESPONSE
VI − Input Voltage − V
4
TA = 25°C
TA = 125°C
3.7
2.7
3
TA = −40°C
∆ VO − Change in
Output Voltage − mV
VI − Input Voltage (Min) − V
IO = 0.5 A
2.7
2
1.5
1.75
2
2.25
2.5
2.75
3
3.25
10
0
Co = 10 µF
TA = 25°C
−10
3.5
0
20
40
60
VO − Output Voltage − V
Figure 15
TPS77x15
TPS77x33
LOAD TRANSIENT RESPONSE
LINE TRANSIENT RESPONSE
VI − Input Voltage − V
Co = 2x47 µF
ESR = 1/2x100 mΩ
VO = 1.5 V
VIN = 2.7 V
0
−50
Co = 10 µF
TA = 25°C
5.3
4.3
∆ VO − Change in
Output Voltage − mV
I O − Output Current − mA
∆ VO − Change in
Output Voltage − mV
Figure 14
50
80 100 120 140 160 180 200
t − Time − µs
500
0
0
20
40
60
80 100 120 140 160 180 200
t − Time − µs
10
0
−10
0
20
40
60
80 100 120 140 160 180 200
t − Time − µs
Figure 17
Figure 16
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SGLS176 − AUGUST 2003
TYPICAL CHARACTERISTICS
TPS77x33
OUTPUT VOLTAGE
vs
TIME (AT STARTUP)
TPS77x33
4
50
VO− Output Voltage − V
Co = 2x47 µF
ESR = 1/2x100 mΩ
VO = 3.3 V
VI = 4.3 V
0
−50
Co = 10 µF
IO = 500 mA
TA = 25°C
3
2
1
0
500
Enable Pulse − V
I O − Output Current − mA
∆ VO − Change in
Output Voltage − mV
LOAD TRANSIENT RESPONSE
0
0
20
40
60
80 100 120 140 160 180 200
t − Time − µs
0
0.1
Figure 18
VI
0.2 0.3
0.4 0.5 0.6 0.7 0.8
t − Time − ms
0.9
1
Figure 19
To Load
IN
OUT
+
EN
Co
GND
R
RL
ESR
Figure 20. Test Circuit for Typical Regions of Stability (Figures 21 through 24) (Fixed Output Options)
12
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TYPICAL CHARACTERISTICS
TYPICAL REGION OF STABILITY
TYPICAL REGION OF STABILITY
EQUIVALENT SERIES RESISTANCE†
vs
OUTPUT CURRENT
EQUIVALENT SERIES RESISTANCE†
vs
OUTPUT CURRENT
10
ESR − Equivalent Series Resistance − Ω
ESR − Equivalent Series Resistance − Ω
10
Region of Instability
1
Region of Stability
VO = 3.3 V
Co = 4.7 µF
VI = 4.3 V
TA = 25°C
0.1
0
100
200
300
400
Region of Instability
1
Region of Stability
VO = 3.3 V
Co = 4.7 µF
VI = 4.3 V
TJ = 125°C
0.1
500
0
100
IO − Output Current − mA
200
Figure 21
400
500
Figure 22
TYPICAL REGION OF STABILITY
TYPICAL REGION OF STABILITY
EQUIVALENT SERIES RESISTANCE†
vs
OUTPUT CURRENT
EQUIVALENT SERIES RESISTANCE†
vs
OUTPUT CURRENT
10
10
ESR − Equivalent Series Resistance − Ω
ESR − Equivalent Series Resistance − Ω
300
IO − Output Current − mA
Region of Instability
1
Region of Stability
VO = 3.3 V
Co = 22 µF
VI = 4.3 V
TA = 25°C
0.1
0
100
200
300
400
500
Region of Instability
1
Region of Stability
VO = 3.3 V
Co = 22 µF
VI = 4.3 V
TJ = 125°C
0.1
0
100
IO − Output Current − mA
200
300
400
500
IO − Output Current − mA
Figure 23
Figure 24
† Equivalent series resistance (ESR) refers to the total series resistance, including the ESR of the capacitor, any series resistance added
externally, and PWB trace resistance to Co.
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APPLICATION INFORMATION
The TPS776xx family includes five fixed-output voltage regulators (1.5 V, 1.8 V, 2.5 V, 2.8 V, and 3.3 V), and an
adjustable regulator, the TPS77601 (adjustable from 1.2 V to 5.5 V).
device operation
The TPS776xx feature very low quiescent current, which remains virtually constant even with varying loads.
Conventional LDO regulators use a pnp pass element, the base current of which is directly proportional to the load
current through the regulator (IB = IC/β). The TPS776xx use a PMOS transistor to pass current; because the gate
of the PMOS is voltage driven, operating current is low and invariable over the full load range.
Another pitfall associated with the pnp-pass element is its tendency to saturate when the device goes into dropout.
The resulting drop in β forces an increase in IB to maintain the load. During power up, this translates to large start-up
currents. Systems with limited supply current may fail to start up. In battery-powered systems, it means rapid battery
discharge when the voltage decays below the minimum required for regulation. The TPS776xx quiescent currents
remain low even when the regulator drops out, eliminating both problems.
The TPS776xx family also features a shutdown mode that places the output in the high-impedance state (essentially
equal to the feedback-divider resistance) and reduces quiescent current to 2 µA. If the shutdown feature is not used,
EN should be tied to ground.
minimum load requirements
The TPS776xx family is stable even at zero load; no minimum load is required for operation.
FB—pin connection (adjustable version only)
The FB pin is an input pin to sense the output voltage and close the loop for the adjustable option . The output voltage
is sensed through a resistor divider network to close the loop as it is shown in Figure 26. Normally, this connection
should be as short as possible; however, the connection can be made near a critical circuit to improve performance
at that point. Internally, FB connects to a high-impedance wide-bandwidth amplifier and noise pickup feeds through
to the regulator output. Routing the FB connection to minimize/avoid noise pickup is essential.
external capacitor requirements
An input capacitor is not usually required; however, a ceramic bypass capacitor (0.047 µF or larger) improves load
transient response and noise rejection if the TPS776xx is located more than a few inches from the power supply.
A higher-capacitance electrolytic capacitor may be necessary if large (hundreds of milliamps) load transients with
fast rise times are anticipated.
Like all low dropout regulators, the TPS776xx require an output capacitor connected between OUT and GND to
stabilize the internal control loop. The minimum recommended capacitance value is 10 µF and the ESR (equivalent
series resistance) must be between 50 mΩ and 1.5 Ω. Capacitor values 10 µF or larger are acceptable, provided
the ESR is less than 1.5 Ω. Solid tantalum electrolytic, aluminum electrolytic, and multilayer ceramic capacitors are
all suitable, provided they meet the requirements described previously.
14
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APPLICATION INFORMATION
external capacitor requirements (continued)
6
VI
7
PG 16
IN
250 kΩ
IN
14
OUT
C1
0.1 µF
5
PG
EN
VO
13
OUT
+
GND
Co
10 µF
3
Figure 25. Typical Application Circuit (Fixed Versions)
programming the TPS77601 adjustable LDO regulator
The output voltage of the TPS77601 adjustable regulator is programmed using an external resistor divider as shown
in Figure 26. The output voltage is calculated using:
V
O
+V
ǒ1 ) R1
Ǔ
R2
ref
(1)
Where:
Vref = 1.1834 V typ (the internal reference voltage)
Resistors R1 and R2 should be chosen for approximately 10-µA divider current. Lower value resistors can be used
but offer no inherent advantage and waste more power. Higher values should be avoided as leakage currents at
FB increase the output voltage error. The recommended design procedure is to choose
R2 = 110 kΩ to set the divider current at approximately 10 µA and then calculate R1 using:
R1 +
ǒ
V
V
Ǔ
O *1
ref
R2
(2)
OUTPUT VOLTAGE
PROGRAMMING GUIDE
TPS77601
VI
0.1 µF
IN
PG
250 kΩ
≥ 1.7 V
≤ 0.9 V
OUTPUT
VOLTAGE
PG Output
EN
OUT
VO
R1
FB / NC
GND
Co
R1
R2
UNIT
2.5 V
121
110
kΩ
3.3 V
196
110
kΩ
3.6 V
226
110
kΩ
4.75 V
332
110
kΩ
R2
Figure 26. TPS77601 Adjustable LDO Regulator Programming
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APPLICATION INFORMATION
power-good indicator
The TPS776xx features a power-good (PG) output that can be used to monitor the status of the regulator. The
internal comparator monitors the output voltage: when the output drops to between 92% and 98% of its nominal
regulated value, the PG output transistor turns on, taking the signal low. The open-drain output requires a pullup
resistor. If not used, it can be left floating. PG can be used to drive power-on reset circuitry or used as a low-battery
indicator.
regulator protection
The TPS776xx PMOS-pass transistors have a built-in back diode that conducts reverse currents when the input
voltage drops below the output voltage (e.g., during power down). Current is conducted from the output to the input
and is not internally limited. When extended reverse voltage is anticipated, external limiting may be appropriate.
The TPS776xx also feature internal current limiting and thermal protection. During normal operation, the TPS776xx
limit output current to approximately 1.7 A. When current limiting engages, the output voltage scales back linearly
until the overcurrent condition ends. While current limiting is designed to prevent gross device failure, care should
be taken not to exceed the power dissipation ratings of the package. If the temperature of the device exceeds
150°C(typ), thermal-protection circuitry shuts it down. Once the device has cooled below 130°C(typ), regulator
operation resumes.
power dissipation and junction temperature
Specified regulator operation is assured to a junction temperature of 125°C; the maximum junction temperature
should be restricted to 125°C under normal operating conditions. This restriction limits the power dissipation the
regulator can handle in any given application. To ensure the junction temperature is within acceptable limits,
calculate the maximum allowable dissipation, PD(max), and the actual dissipation, PD, which must be less than or
equal to PD(max).
The maximum-power-dissipation limit is determined using the following equation:
P
T max * T
A
+ J
D(max)
R
qJA
Where:
TJmax is the maximum allowable junction temperature.
RθJA is the thermal resistance junction-to-ambient for the package, i.e., 32.6°C/W for the 20-terminal
PWP with no airflow.
TA is the ambient temperature.
The regulator dissipation is calculated using:
P
D
ǒ
Ǔ
+ V *V
I
O
I
O
Power dissipation resulting from quiescent current is negligible. Excessive power dissipation will trigger the thermal
protection circuit.
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