FEATURES
LT1764 Series
3A, Fast Transient
Response, Low Noise,
LDO Regulators
U
DESCRIPTIO
■
Optimized for Fast Transient Response
■
Output Current: 3A
■
Dropout Voltage: 340mV at 3A
■
Low Noise: 40µV
■
1mA Quiescent Current
■
Wide Input Voltage Range: 2.7V to 20V
■
No Protection Diodes Needed
■
Controlled Quiescent Current in Dropout
■
Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3.3V
■
Adjustable Output from 1.21V to 20V
■
<1µA Quiescent Current in Shutdown
■
Stable with 10µF Output Capacitor
■
Reverse Battery Protection
■
No Reverse Current
■
Thermal Limiting
■
Available in 5-Lead TO-220, DD and 16-Lead
(10Hz to 100kHz)
RMS
TSSOP Packages
U
APPLICATIO S
■
3.3V to 2.5V Logic Power Supply
■
Post Regulator for Switching Supplies
The LT
®
1764 is a low dropout regulator optimized for fast
transient response. The device is capable of supplying 3A
of output current with a dropout voltage of 340mV. Operating quiescent current is 1mA, dropping to <1µA 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 LT1764 has very
low output voltage noise which makes the device ideal for
sensitive RF supply applications.
Output voltage range is from 1.21V to 20V. The LT1764
regulators are stable with output capacitors as low as 10µF.
Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting and reverse current protection. The device is available in fixed output
voltages of 1.5V, 1.8V, 2.5V, 3.3V and as an adjustable
device with a 1.21V reference voltage. The LT1764 regulators are available in 5-lead TO-220, DD and Exposed Pad
16-lead TSSOP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 6144250, 6118263.
TYPICAL APPLICATIO
to 2.5V
3.3V
IN
IN
> 3V
V
IN
10µF
LT1764-2.5
SHDN
OUT
SENSE
GND
Regulator
OUT
U
Dropout Voltage
400
350
300
2.5V
++
3A
10µF
1764 TA01
250
200
150
100
DROPOUT VOLTAGE (mV)
50
0
0 0.5
1.0 2.01.5
LOAD CURRENT (A)
2.5
3.0
1764 TA02
1764fb
1
LT1764 Series
FE PACKAGE
16-LEAD PLASTIC TSSOP
EXPOSED PAD (PIN 17) IS GND. MUST BE
SOLDERED TO THE PCB.
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
GND
NC
OUT
OUT
OUT
SENSE/ADJ*
GND
GND
GND
NC
IN
IN
IN
NC
SHDN
GND
17
WW
W
ABSOLUTE MAXIMUM RATINGS
U
(Note 1)
IN Pin Voltage ........................................................ ±20V
OUT Pin Voltage .................................................... ±20V
Input to Output Differential Voltage (Note 12) ....... ±20V
SENSE Pin Voltage ............................................... ±20V
ADJ Pin Voltage ...................................................... ±7V
U
W
PACKAGE/ORDER INFORMATION
FRONT VIEW
SENSE/ADJ*
5
OUT
TAB IS
GND
*PIN 5 = SENSE FOR LT1764-1.5/LT1764-1.8/
LT1764-2.5/LT1764-3.3
= ADJ FOR LT1764
T
JMAX
4
3
2
1
Q PACKAGE
5-LEAD PLASTIC DD
= 150°C, θJA = 30°C/ W
GND
IN
SHDN
TAB IS
GND
*PIN 5 = SENSE FOR LT1764-1.5/LT1764-1.8/
FRONT VIEW
T PACKAGE
5-LEAD PLASTIC TO-220
LT1764-2.5/LT1764-3.3
= ADJ FOR LT1764
= 150°C, θJA = 50°C/ W
T
JMAX
SHDN Pin Voltage ................................................. ±20V
Output Short-Circuit Duration ......................... Indefinite
Operating Junction Temperature Range –40°C to 125°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
U
5
4
3
2
1
SENSE/
ADJ*
OUT
GND
IN
SHDN
*PIN 6 = SENSE FOR LT1764-1.5/
LT1764-1.8/LT1764-2.5/
LT1764-3.3
= ADJ FOR LT1764
T
= 150°C, θJA = 38°C/ W
JMAX
Order Options
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
2
ORDER PART NUMBER
LT1764EQ
LT1764EQ-1.5
LT1764EQ-1.8
LT1764EQ-2.5
LT1764EQ-3.3
Tape and Reel: Add #TR
ORDER PART NUMBER
LT1764ET
LT1764ET-1.5
LT1764ET-1.8
LT1764ET-2.5
LT1764ET-3.3
ORDER PART
NUMBER
LT1764EFE
LT1764EFE-1.5
LT1764EFE-1.8
LT1764EFE-2.5
LT1764EFE-3.3
FE PART
MARKING
1764EFE
1764EFE15
1764EFE18
1764EFE25
1764EFE33
1764fb
LT1764 Series
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Input Voltage I
(Notes 3, 11) I
Regulated Output Voltage LT1764-1.5 VIN = 2.21V, I
(Note 4) 2.7V < V
ADJ Pin Voltage LT1764 VIN = 2.21V, I
(Notes 3, 4) 2.7V < V
Line Regulation LT1764-1.5 ∆VIN = 2.21V to 20V, I
Load Regulation LT1764-1.5 VIN = 2.7V, ∆I
Dropout Voltage I
V
= V
IN
OUT(NOMINAL)
(Notes 5, 6, 11) I
= 0.5A 1.7 V
LOAD
= 1.5A 1.9 V
LOAD
I
= 2.7A, 110°C < TJ ≤ 125°C 2.3 2.7 V
LOAD
= 3A, –40°C ≤ TJ ≤ 110°C 2.3 2.7 V
I
LOAD
= 1mA 1.477 1.500 1.523 V
LOAD
< 20V, 1mA < I
IN
2.7V < V
LT1764-1.8 VIN = 2.3V, I
2.8V < V
2.8V < V
LT1764-2.5 VIN = 3V, I
3.5V < V
3.5V < V
LT1764-3.3 VIN = 3.8V, I
4.3V < V
4.3V < V
2.7V < V
LT1764-1.8 ∆V
LT1764-2.5 ∆V
LT1764-3.3 ∆V
LT1764 (Note 3) ∆V
LT1764-1.8 VIN = 2.8V, ∆I
LT1764-2.5 VIN = 3.5V, ∆I
LT1764-3.3 VIN = 4.3V, ∆I
LT1764 (Note 3) VIN = 2.7V, ∆I
= 1mA 0.02 0.05 V
LOAD
I
= 1mA
LOAD
= 100mA 0.07 0.13 V
LOAD
= 100mA
I
LOAD
I
= 500mA 0.14 0.20 V
LOAD
I
= 500mA
LOAD
I
= 1.5A 0.25 0.33 V
LOAD
= 1.5A
I
LOAD
I
= 2.7A, 110°C < TJ ≤ 125°C 0.66 V
LOAD
I
= 3A 0.34 0.45 V
LOAD
I
= 3A, –40°C ≤ TJ ≤ 110°C 0.66 V
LOAD
< 20V, 1mA < I
IN
LOAD
< 20V, 1mA < I
IN
< 20V, 1mA < I
IN
= 1mA 2.462 2.500 2.538 V
LOAD
< 20V, 1mA < I
IN
< 20V, 1mA < I
IN
LOAD
< 20V, 1mA < I
IN
< 20V, 1mA < I
IN
LOAD
< 20V, 1mA < I
IN
< 20V, 1mA < I
IN
= 2.3V to 20V, I
IN
= 3V to 20V, I
IN
= 3.8V to 20V, I
IN
= 2.21V to 20V, I
IN
V
= 2.7V, ∆I
IN
= 2.7V, ∆I
V
IN
V
= 2.8V, ∆I
IN
= 2.8V, ∆I
V
IN
V
= 3.5V, ∆I
IN
= 3.5V, ∆I
V
IN
V
= 4.3V, ∆I
IN
= 4.3V, ∆I
V
IN
V
= 2.7V, ∆I
IN
V
= 2.7V, ∆I
IN
= 1mA 1.773 1.800 1.827 V
= 1mA 3.250 3.300 3.350 V
= 1mA 1.192 1.210 1.228 V
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
< 3A, –40°C ≤ TJ ≤ 110°C 1.447 1.500 1.545 V
LOAD
< 2.7A, 110°C < TJ ≤ 125°C 1.447 1.500 1.545 V
LOAD
< 3A, –40°C ≤ TJ ≤ 110°C 1.737 1.800 1.854 V
LOAD
< 2.7A, 110°C < TJ ≤ 125°C 1.737 1.800 1.854 V
LOAD
< 3A, –40°C ≤ TJ ≤ 110°C 2.412 2.500 2.575 V
LOAD
< 2.7A, 110°C < TJ ≤ 125°C 2.412 2.500 2.575 V
LOAD
< 3A, –40°C ≤ TJ ≤ 110°C 3.183 3.300 3.400 V
LOAD
< 2.7A, 110°C < TJ ≤ 125°C 3.183 3.300 3.400 V
LOAD
< 3A, –40°C ≤ TJ ≤ 110°C 1.168 1.210 1.246 V
LOAD
< 2.7A, 110°C < TJ ≤ 125°C 1.168 1.210 1.246 V
LOAD
LOAD
LOAD
LOAD
LOAD
= 1mA
= 1mA
= 1mA
LOAD
= 1mA
= 1mA
●
●
●
●
●
2.5 10 mV
310mV
410mV
4.5 10 mV
210mV
= 1mA to 3A 3 7 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C23mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C23mV
= 1mA to 3A 4 8 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C25mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C25mV
= 1mA to 3A 4 10 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C30mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C30mV
= 1mA to 3A 4 12 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C40mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C40mV
= 1mA to 3A 2 5 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C20mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C20mV
●
●
●
●
0.10 V
0.18 V
0.27 V
0.40 V
1764fb
3
LT1764 Series
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
GND Pin Current I
= V
V
IN
OUT(NOMINAL)
+ 1V I
(Notes 5, 7) I
Output Voltage Noise C
ADJ Pin Bias Current (Notes 3, 8) 310µA
Shutdown Threshold V
SHDN Pin Current V
(Note 9) V
Quiescent Current in Shutdown VIN = 6V, V
Ripple Rejection VIN – V
Current Limit VIN = 7V, V
Input Reverse Leakage Current VIN = –20V, V
Reverse Output Current (Note 10) LT1764-1.5 V
= 0mA
LOAD
= 1mA
LOAD
= 100mA
LOAD
I
= 500mA
LOAD
= 1.5A
I
LOAD
= 2.7A, 110°C < TJ ≤ 125°C 120 200 mA
I
LOAD
I
= 3A, –40°C ≤ TJ ≤ 110°C 120 200 mA
LOAD
= 10µF, I
OUT
= Off to On
OUT
= On to Off
V
OUT
= 0V 0.01 1 µA
SHDN
= 20V 7 30 µA
SHDN
OUT
= 120Hz, I
f
RIPPLE
= 3A, BW = 10Hz to 100kHz 40 µV
LOAD
= 0V 0.01 1 µA
SHDN
= 1.5V (Avg), V
= 1.5A
LOAD
= 0V 4 A
OUT
RIPPLE
= 0.5V
,5563dB
P-P
●
●
●
●
●
●
●
0.25 0.75 V
1 1.5 mA
1.1 1.6 mA
3.5 5 mA
11 18 mA
40 75 mA
0.9 2 V
LT1764-1.8, LT1764-2.5, LT1764-3.3
= V
V
IN
= V
V
IN
OUT(NOMINAL)
OUT(NOMINAL)
+ 1V, ∆V
+ 1V, ∆V
= – 0.1V, –40°C ≤ TJ ≤ 110°C 3.1 A
OUT
= – 0.1V, 110°C < TJ ≤ 125°C 2.8 A
OUT
LT1764, LT1764-1.5
= 2.7V, ∆V
V
IN
V
= 2.7V, ∆V
IN
LT1764-1.8 V
LT1764-2.5 V
LT1764-3.3 V
LT1764 (Note 3) V
= – 0.1V, –40°C ≤ TJ ≤ 110°C 3.1 A
OUT
= – 0.1V, 110°C < TJ ≤ 125°C 2.8 A
OUT
= 0V
OUT
= 1.5V, VIN < 1.5V 600 1200 µA
OUT
= 1.8V, VIN < 1.8V 600 1200 µA
OUT
= 2.5V, VIN < 2.5V 600 1200 µA
OUT
= 3.3V, VIN < 3.3V 600 1200 µA
OUT
= 1.21V, VIN < 1.21V 300 600 µA
OUT
●
1mA
RMS
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT1764 regulators are tested and specified under pulse load
conditions such that T
≈ TA. The LT1764 is 100% tested at TA = 25°C.
J
Performance at –40°C and 125°C is assured by design, characterization
and correlation with statistical process controls.
Note 3: The LT1764 (adjustable version) is tested and specified for these
conditions with the ADJ pin connected to the OUT pin.
Note 4. Operating conditions are limited by maximum junction
temperature. The regulated output voltage specification will 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.
Note 5: To satisfy requirements for minimum input voltage, the LT1764
(adjustable version) is tested and specified for these conditions with an
external resistor divider (two 4.12k resistors) for an output voltage of 2.42V.
The external resistor divider will add a 300µA DC load on the output.
4
Note 6: Dropout voltage is the minimum input to output voltage differential
needed to maintain regulation at a specified output current. In dropout, the
output voltage will be equal to: V
Note 7: GND pin current is tested with V
V
= 2.7V (whichever is greater) and a current source load. The GND pin
IN
IN
– V
DROPOUT
= V
IN
.
OUT(NOMINAL)
+ 1V or
current will decrease at higher input voltages.
Note 8: ADJ pin bias current flows into the ADJ pin.
Note 9: SHDN pin current flows into the SHDN pin.
Note 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.
Note 11. For the LT1764, LT1764-1.5 and LT1764-1.8 dropout voltage will
be limited by the minimum input voltage specification under some output
voltage/load conditions.
Note 12. All combinations of absolute maximum input voltage and
absolute maximum output voltage cannot be achieved. The absolute
maximum differential from input to output is ±20V. For example, with
V
= 20V, V
IN
cannot be pulled below ground.
OUT
1764fb
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
25
1756 G06
–25 0 50
2.58
2.56
2.54
2.52
2.50
2.48
2.46
2.44
2.42
75 100 125
IL = 1mA
TEMPERATURE (°C)
–50
DROPOUT VOLTAGE (mV)
400
500
600
25 75
1764 G03
300
200
–25 0
50 100 125
100
0
IL = 3A
IL = 1.5A
IL = 0.5A
IL = 100mA
IL = 1mA
UW
TYPICAL PERFOR A CE CHARACTERISTICS
Typical Dropout Voltage Guaranteed Dropout Voltage Dropout Voltage
600
500
700
600
= TEST POINTS
LT1764 Series
400
300
200
DROPOUT VOLTAGE (mV)
100
0
0
TJ = 125°C
1.0 1.5 2.0
0.5
OUTPUT CURRENT (A)
TJ = 25°C
2.5 3.0
1764 G01
500
400
300
200
100
GUARANTEED DROPOUT VOLTAGE (mV)
0
0
TJ ≤ 125°C
TJ ≤ 25°C
0.5 1.0
OUTPUT CURRENT (A)
2.0 3.0
1.5 2.5
1764 G02
Quiescent Current LT1764-1.8 Output Voltage LT1764-2.5 Output Voltage
1.4
LT1764-1.8/2.5/3.3
1.2
1.0
0.8
0.6
0.4
VIN = 6V
QUIESCENT CURRENT (mA)
0.2
0
–50
=
R
L
IL = 0
V
SHDN
–25 0
∞
= V
IN
TEMPERATURE (°C)
LT1764
50 100 125
25 75
1764 G04
1.84
IL = 1mA
1.83
1.82
1.81
1.80
1.79
OUTPUT VOLTAGE (V)
1.78
1.77
1.76
–25 0 50
–50
25
TEMPERATURE (°C)
75 100 125
1756 G05
LT1764-3.3 Output Voltage LT1764 ADJ Pin Voltage LT1764-1.8 Quiescent Current
3.38
IL = 1mA
3.36
3.34
3.32
3.30
3.28
OUTPUT VOLTAGE (V)
3.26
3.24
3.22
–50
–25 0 50
25
TEMPERATURE (°C)
75 100 125
1756 G07
1.230
IL = 1mA
1.225
1.220
1.215
1.210
1.205
ADJ PIN VOLTAGE (V)
1.200
1.195
1.190
–25 0 50
–50
25
TEMPERATURE (°C)
75 100 125
1756 G08
40
TJ = 25°C
=
∞
R
35
L
V
= V
SHDN
30
25
20
15
10
QUIESCENT CURRENT (mA)
5
0
0
IN
246 107135 9
INPUT VOLTAGE (V)
8
1764 G09
1764fb
5
LT1764 Series
UW
TYPICAL PERFOR A CE CHARACTERISTICS
LT1764-2.5 Quiescent Current LT1764-3.3 Quiescent Current LT1764 Quiescent Current
40
TJ = 25°C
=
∞
R
35
L
V
= V
SHDN
IN
30
25
20
15
10
QUIESCENT CURRENT (mA)
5
0
246 107135 9
0
8
INPUT VOLTAGE (V)
1764 G10
LT1764-1.8 GND Pin Current LT1764-2.5 GND Pin Current LT1764-3.3 GND Pin Current
20.0
17.5
15.0
12.5
RL = 3.6Ω
I
= 500mA*
L
10.0
7.5
GND PIN CURRENT (mA)
5.0
2.5
0
RL = 18Ω
= 100mA*
I
L
3578246 10
10
INPUT VOLTAGE (V)
TJ = 25°C
= V
V
SHDN
*FOR V
RL = 6Ω
= 300mA*
I
L
OUT
IN
= 1.8V
9
1764 G13
40
35
30
25
20
15
10
QUIESCENT CURRENT (mA)
5
0
246 107135 9
0
INPUT VOLTAGE (V)
40
35
30
25
RL = 5Ω
= 500mA*
I
L
20
15
GND PIN CURRENT (mA)
10
5
0
3578246 10
10
INPUT VOLTAGE (V)
RL = 25Ω
= 100mA*
I
L
= 25°C
T
J
V
SHDN
*FOR V
TJ = 25°C
=
∞
R
L
V
= V
SHDN
8
1764 G11
= V
IN
= 2.5V
OUT
RL = 8.33Ω
= 300mA*
I
L
9
1764 G14
1.6
TJ = 25°C
= 4.3k
R
1.4
L
= V
IN
V
SHDN
IN
1.2
1.0
0.8
0.6
0.4
QUIESCENT CURRENT (mA)
0.2
0
4 8 12 20142 6 10 18
0
INPUT VOLTAGE (V)
80
70
60
50
40
RL = 6.6Ω
= 500mA*
I
L
30
GND PIN CURRENT (mA)
20
10
0
3578246 10
10
INPUT VOLTAGE (V)
TJ = 25°C
V
SHDN
*FOR V
RL = 11Ω
= 300mA*
I
L
16
= V
IN
= 3.3V
OUT
RL = 33Ω
= 100mA*
I
L
1764 G12
9
1764 G15
LT1764 GND Pin Current LT1764-1.8 GND Pin Current LT1764-2.5 GND Pin Current
15
TJ = 25°C
= V
V
SHDN
IN
*FOR V
12
OUT
= 1.21V
9
6
RL = 12.1Ω
= 100mA*
I
GND PIN CURRENT (mA)
3
0
0
L
2
3
19
INPUT VOLTAGE (V)
RL = 4.33Ω
= 300mA*
I
L
4
5
RL = 2.42Ω
= 500mA*
I
L
6
7
150
120
RL = 0.6Ω
= 3A*
90
60
GND PIN CURRENT (mA)
30
8
10
0
0
I
L
RL = 1.2Ω
I
2
3
19
= 1.5A*
L
4
5
TJ = 25°C
= V
V
SHDN
*FOR V
RL = 2.57Ω
I
L
6
7
IN
= 1.8V
OUT
= 0.7A*
8
10
INPUT VOLTAGE (V)
1764 G16
1764 G17
200
160
120
80
RL = 1.66Ω
= 1.5A*
GND PIN CURRENT (mA)
40
0
19
0
I
L
2
3
4
INPUT VOLTAGE (V)
6
TJ = 25°C
V
SHDN
*FOR V
RL = 0.83Ω
= 3A*
I
L
6
5
= V
IN
= 2.5V
OUT
RL = 3.57Ω
= 0.7A*
I
L
7
8
10
1764 G18
1764fb
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