LT1764 - 3A, Fast Transient Response, Low Noise, LDO Regulators

LT1764 Series
3A, Fast Transient
Response, Low Noise,
LDO Regulators
U
FEATURES
DESCRIPTIO
■
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.
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
Optimized for Fast Transient Response
Output Current: 3A
Dropout Voltage: 340mV at 3A
Low Noise: 40µVRMS (10Hz to 100kHz)
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
TSSOP Packages
U
APPLICATIO S
■
, 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.
3.3V to 2.5V Logic Power Supply
Post Regulator for Switching Supplies
U
■
TYPICAL APPLICATIO
Dropout Voltage
400
3.3VIN to 2.5VOUT Regulator
VIN > 3V
OUT
2.5V
3A
+
10µF
10µF
LT1764-2.5
SHDN SENSE
GND
DROPOUT VOLTAGE (mV)
IN
+
350
300
250
200
150
100
1764 TA01
50
0
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
2.5
3.0
1764 TA02
1764fb
1
LT1764 Series
U
W W
W
ABSOLUTE MAXIMUM RATINGS (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
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
W
U
U
PACKAGE/ORDER INFORMATION
TOP VIEW
FRONT VIEW
FRONT VIEW
TAB IS
GND
5
SENSE/ADJ*
5
SENSE/
ADJ*
4
OUT
4
OUT
3
GND
3
GND
2
IN
2
IN
1
SHDN
1
SHDN
Q PACKAGE
5-LEAD PLASTIC DD
*PIN 5 = SENSE FOR LT1764-1.5/LT1764-1.8/
LT1764-2.5/LT1764-3.3
= ADJ FOR LT1764
TJMAX = 150°C, θJA = 30°C/ W
T PACKAGE
5-LEAD PLASTIC TO-220
TAB IS
GND
*PIN 5 = SENSE FOR LT1764-1.5/LT1764-1.8/
LT1764-2.5/LT1764-3.3
= ADJ FOR LT1764
TJMAX = 150°C, θJA = 50°C/ W
GND
1
16 GND
NC
2
15 NC
OUT
3
14 IN
OUT
4
OUT
5
12 IN
SENSE/ADJ*
6
11 NC
GND
7
10 SHDN
GND
8
9
17
13 IN
GND
FE PACKAGE
16-LEAD PLASTIC TSSOP
EXPOSED PAD (PIN 17) IS GND. MUST BE
SOLDERED TO THE PCB.
*PIN 6 = SENSE FOR LT1764-1.5/
LT1764-1.8/LT1764-2.5/
LT1764-3.3
= ADJ FOR LT1764
TJMAX = 150°C, θJA = 38°C/ W
ORDER PART NUMBER
ORDER PART NUMBER
ORDER PART
NUMBER
FE PART
MARKING
LT1764EQ
LT1764EQ-1.5
LT1764EQ-1.8
LT1764EQ-2.5
LT1764EQ-3.3
LT1764ET
LT1764ET-1.5
LT1764ET-1.8
LT1764ET-2.5
LT1764ET-3.3
LT1764EFE
LT1764EFE-1.5
LT1764EFE-1.8
LT1764EFE-2.5
LT1764EFE-3.3
1764EFE
1764EFE15
1764EFE18
1764EFE25
1764EFE33
Order Options Tape and Reel: Add #TR
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.
1764fb
2
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
Minimum Input Voltage
(Notes 3, 11)
ILOAD = 0.5A
ILOAD = 1.5A
ILOAD = 2.7A, 110°C < TJ ≤ 125°C
ILOAD = 3A, – 40°C ≤ TJ ≤ 110°C
Regulated Output Voltage
(Note 4)
MIN
TYP
MAX
UNITS
1.7
1.9
2.3
2.3
2.7
2.7
V
V
V
V
LT1764-1.5 VIN = 2.21V, ILOAD = 1mA
2.7V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C
2.7V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C
1.477
1.447
1.447
1.500
1.500
1.500
1.523
1.545
1.545
V
V
V
LT1764-1.8 VIN = 2.3V, ILOAD = 1mA
2.8V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C
2.8V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C
1.773
1.737
1.737
1.800
1.800
1.800
1.827
1.854
1.854
V
V
V
LT1764-2.5 VIN = 3V, ILOAD = 1mA
3.5V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C
3.5V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C
2.462
2.412
2.412
2.500
2.500
2.500
2.538
2.575
2.575
V
V
V
LT1764-3.3 VIN = 3.8V, ILOAD = 1mA
4.3V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C
4.3V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C
3.250
3.183
3.183
3.300
3.300
3.300
3.350
3.400
3.400
V
V
V
ADJ Pin Voltage
(Notes 3, 4)
LT1764
1.192
1.168
1.168
1.210
1.210
1.210
1.228
1.246
1.246
V
V
V
Line Regulation
LT1764-1.5
LT1764-1.8
LT1764-2.5
LT1764-3.3
LT1764 (Note 3)
∆VIN = 2.21V to 20V, ILOAD = 1mA
∆VIN = 2.3V to 20V, ILOAD = 1mA
∆VIN = 3V to 20V, ILOAD = 1mA
∆VIN = 3.8V to 20V, ILOAD = 1mA
∆VIN = 2.21V to 20V, ILOAD = 1mA
2.5
3
4
4.5
2
10
10
10
10
10
mV
mV
mV
mV
mV
Load Regulation
LT1764-1.5
VIN = 2.7V, ∆ILOAD = 1mA to 3A
VIN = 2.7V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C
VIN = 2.7V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C
3
7
23
23
mV
mV
mV
LT1764-1.8
VIN = 2.8V, ∆ILOAD = 1mA to 3A
VIN = 2.8V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C
VIN = 2.8V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C
4
8
25
25
mV
mV
mV
LT1764-2.5
VIN = 3.5V, ∆ILOAD = 1mA to 3A
VIN = 3.5V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C
VIN = 3.5V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C
4
10
30
30
mV
mV
mV
LT1764-3.3
VIN = 4.3V, ∆ILOAD = 1mA to 3A
VIN = 4.3V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C
VIN = 4.3V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C
4
12
40
40
mV
mV
mV
LT1764 (Note 3) VIN = 2.7V, ∆ILOAD = 1mA to 3A
VIN = 2.7V, ∆ILOAD = 1mA to 3A, – 40°C ≤ TJ ≤ 110°C
VIN = 2.7V, ∆ILOAD = 1mA to 2.7A, 110°C < TJ ≤ 125°C
2
5
20
20
mV
mV
mV
0.02
0.05
0.10
V
V
0.07
0.13
0.18
V
V
0.14
0.20
0.27
V
V
0.25
0.33
0.40
V
V
0.66
V
0.34
0.45
0.66
V
V
VIN = 2.21V, ILOAD = 1mA
2.7V < VIN < 20V, 1mA < ILOAD < 3A, – 40°C ≤ TJ ≤ 110°C
2.7V < VIN < 20V, 1mA < ILOAD < 2.7A, 110°C < TJ ≤ 125°C
●
●
●
●
●
Dropout Voltage
VIN = VOUT(NOMINAL)
ILOAD = 1mA
ILOAD = 1mA
●
(Notes 5, 6, 11)
ILOAD = 100mA
ILOAD = 100mA
●
ILOAD = 500mA
ILOAD = 500mA
●
ILOAD = 1.5A
ILOAD = 1.5A
●
ILOAD = 2.7A, 110°C < TJ ≤ 125°C
ILOAD = 3A
ILOAD = 3A, – 40°C ≤ TJ ≤ 110°C
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
GND Pin Current
VIN = VOUT(NOMINAL) + 1V
(Notes 5, 7)
ILOAD = 0mA
ILOAD = 1mA
ILOAD = 100mA
ILOAD = 500mA
ILOAD = 1.5A
ILOAD = 2.7A, 110°C < TJ ≤ 125°C
ILOAD = 3A, – 40°C ≤ TJ ≤ 110°C
Output Voltage Noise
COUT = 10µF, ILOAD = 3A, BW = 10Hz to 100kHz
ADJ Pin Bias Current
(Notes 3, 8)
Shutdown Threshold
VOUT = Off to On
VOUT = On to Off
●
●
●
●
●
TYP
MAX
UNITS
1
1.1
3.5
11
40
120
120
1.5
1.6
5
18
75
200
200
mA
mA
mA
mA
mA
mA
mA
µVRMS
40
●
●
0.25
3
10
µA
0.9
0.75
2
V
V
SHDN Pin Current
(Note 9)
VSHDN = 0V
VSHDN = 20V
0.01
7
1
30
µA
µA
Quiescent Current in Shutdown
VIN = 6V, VSHDN = 0V
0.01
1
µA
Ripple Rejection
VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P,
fRIPPLE = 120Hz, ILOAD = 1.5A
Current Limit
VIN = 7V, VOUT = 0V
Input Reverse Leakage Current
55
63
dB
4
A
LT1764-1.8, LT1764-2.5, LT1764-3.3
VIN = VOUT(NOMINAL) + 1V, ∆VOUT = – 0.1V, – 40°C ≤ TJ ≤ 110°C
VIN = VOUT(NOMINAL) + 1V, ∆VOUT = – 0.1V, 110°C < TJ ≤ 125°C
3.1
2.8
A
A
LT1764, LT1764-1.5
VIN = 2.7V, ∆VOUT = – 0.1V, – 40°C ≤ TJ ≤ 110°C
VIN = 2.7V, ∆VOUT = – 0.1V, 110°C < TJ ≤ 125°C
3.1
2.8
A
A
VIN = – 20V, VOUT = 0V
Reverse Output Current (Note 10) LT1764-1.5 VOUT = 1.5V, VIN < 1.5V
LT1764-1.8 VOUT = 1.8V, VIN < 1.8V
LT1764-2.5 VOUT = 2.5V, VIN < 2.5V
LT1764-3.3 VOUT = 3.3V, VIN < 3.3V
LT1764 (Note 3) VOUT = 1.21V, VIN < 1.21V
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 TJ ≈ TA. The LT1764 is 100% tested at TA = 25°C.
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.
●
600
600
600
600
300
1
mA
1200
1200
1200
1200
600
µA
µA
µA
µA
µA
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: VIN – VDROPOUT.
Note 7: GND pin current is tested with VIN = VOUT(NOMINAL) + 1V or
VIN = 2.7V (whichever is greater) and a current source load. The GND pin
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
VIN = 20V, VOUT cannot be pulled below ground.
1764fb
4
LT1764 Series
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Typical Dropout Voltage
Guaranteed Dropout Voltage
GUARANTEED DROPOUT VOLTAGE (mV)
700
DROPOUT VOLTAGE (mV)
500
400
TJ = 125°C
300
200
TJ = 25°C
100
0
0
0.5
1.0
1.5
2.0
OUTPUT CURRENT (A)
2.5
= TEST POINTS
600
500
500
TJ ≤ 125°C
400
300
TJ ≤ 25°C
200
0
Quiescent Current
LT1764
0.8
0.6
VIN = 6V
RL = ∞
IL = 0
VSHDN = VIN
50
25
75
0
TEMPERATURE (°C)
0.5
2.0
1.5
1.0
OUTPUT CURRENT (A)
IL = 1mA
2.56
1.82
2.54
1.81
1.80
1.79
1.78
3.34
1.220
3.28
3.26
3.24
75
50
25
TEMPERATURE (°C)
0
100
75
50
25
TEMPERATURE (°C)
2.48
2.46
2.42
– 50 – 25
125
100
125
1756 G07
75
50
25
TEMPERATURE (°C)
0
100
125
1756 G06
LT1764-1.8 Quiescent Current
40
IL = 1mA
1.215
1.210
1.205
1.200
1.190
– 50 – 25
TJ = 25°C
RL = ∞
VSHDN = VIN
35
30
25
20
15
10
5
1.195
0
2.50
2.44
QUIESCENT CURRENT (mA)
1.225
ADJ PIN VOLTAGE (V)
OUTPUT VOLTAGE (V)
IL = 1mA
3.36
3.22
– 50 – 25
2.52
LT1764 ADJ Pin Voltage
1.230
125
IL = 1mA
1756 G05
LT1764-3.3 Output Voltage
3.30
100
LT1764-2.5 Output Voltage
1.83
1.76
– 50 – 25
125
3.32
50
25
75
0
TEMPERATURE (°C)
1764 G03
2.58
1764 G04
3.38
3.0
2.5
1.77
100
IL = 100mA
0
–50 –25
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
QUIESCENT CURRENT (mA)
LT1764-1.8/2.5/3.3
0
–50 –25
IL = 0.5A
LT1764-1.8 Output Voltage
1.84
1.0
0.2
IL = 1.5A
200
1764 G02
1.4
0.4
IL = 3A
300
IL = 1mA
1764 G01
1.2
400
100
100
0
3.0
Dropout Voltage
600
DROPOUT VOLTAGE (mV)
600
0
75
50
25
TEMPERATURE (°C)
0
100
125
1756 G08
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1764 G09
1764fb
5
LT1764 Series
U W
TYPICAL PERFOR A CE CHARACTERISTICS
LT1764-2.5 Quiescent Current
LT1764-3.3 Quiescent Current
TJ = 25°C
RL = ∞
VSHDN = VIN
1.6
TJ = 25°C
RL = ∞
VSHDN = VIN
35
QUIESCENT CURRENT (mA)
30
25
20
15
10
5
30
25
20
15
10
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
1764 G10
LT1764-1.8 GND Pin Current
0
RL = 6Ω
IL = 300mA*
7.5
5.0
RL = 18Ω
IL = 100mA*
2.5
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
TJ = 25°C
VSHDN = VIN
*FOR VOUT = 2.5V
30
RL = 5Ω
IL = 500mA*
25
20
RL = 25Ω
IL = 100mA*
15
RL = 8.33Ω
IL = 300mA*
10
10
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
150
8
9
GND PIN CURRENT (mA)
RL = 4.33Ω
IL = 300mA*
6
RL = 12.1Ω
IL = 100mA*
3
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1764 G16
RL = 33Ω
IL = 100mA*
20
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
60
RL = 1.2Ω
IL = 1.5A*
0
TJ = 25°C
VSHDN = VIN
*FOR VOUT = 2.5V
160
RL = 2.57Ω
IL = 0.7A*
RL = 0.83Ω
IL = 3A*
120
80
RL = 1.66Ω
IL = 1.5A*
40
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
10
1764 G15
200
RL = 0.6Ω
IL = 3A*
90
9
LT1764-2.5 GND Pin Current
30
2
RL = 11Ω
IL = 300mA*
30
10
TJ = 25°C
VSHDN = VIN
*FOR VOUT = 1.8V
120
9
RL = 6.6Ω
IL = 500mA*
40
LT1764-1.8 GND Pin Current
RL = 2.42Ω
IL = 500mA*
1
50
1764 G14
TJ = 25°C
VSHDN = VIN
*FOR VOUT = 1.21V
0
60
0
0
LT1764 GND Pin Current
12
TJ = 25°C
VSHDN = VIN
*FOR VOUT = 3.3V
70
10
1764 G13
15
6 8 10 12 14 16 18 20
INPUT VOLTAGE (V)
LT1764-3.3 GND Pin Current
0
1
4
1764 G12
5
0
0
2
80
35
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
10.0
0.4
10
GND PIN CURRENT (mA)
TJ = 25°C
VSHDN = VIN
*FOR VOUT = 1.8V
12.5
0.6
LT1764-2.5 GND Pin Current
15.0
GND PIN CURRENT (mA)
9
40
RL = 3.6Ω
IL = 500mA*
0.8
1764 G11
20.0
17.5
1.0
0
0
0
1.2
0.2
5
0
TJ = 25°C
RL = 4.3k
VSHDN = VIN
1.4
GND PIN CURRENT (mA)
QUIESCENT CURRENT (mA)
35
0
LT1764 Quiescent Current
40
QUIESCENT CURRENT (mA)
40
9
10
1764 G17
0
1
2
RL = 3.57Ω
IL = 0.7A*
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1764 G18
1764fb
6
LT1764 Series
U W
TYPICAL PERFOR A CE CHARACTERISTICS
200
150
TJ = 25°C
VSHDN = VIN
*FOR VOUT = 3.3V
RL = 1.1Ω
IL = 3A*
120
80
RL = 2.2Ω
IL = 1.5A*
RL = 4.71Ω
IL = 0.7A*
40
GND Pin Current vs ILOAD
160
TJ = 25°C
VSHDN = VIN
*FOR VOUT = 1.21V
120
GND PIN CURRENT (mA)
160
GND PIN CURRENT (mA)
LT1764 GND Pin Current
RL = 0.4Ω
IL = 3A*
90
RL = 0.81Ω
IL = 1.5A*
60
RL = 1.73Ω
IL = 0.7A*
VIN = VOUT(NOM) + 1V
140
GND PIN CURRENT (mA)
LT1764-3.3 GND Pin Current
30
120
100
80
60
40
20
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
0
10
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
1764 G19
0.6
0.5
0.4
0.3
0.2
0.1
50
25
0
75
TEMPERATURE (°C)
100
0.7
0.6
IL = 1mA
0.5
0.4
0.3
0.2
6
5
4
3
2
0
50
25
0
75
TEMPERATURE (°C)
100
125
5
4
3
2
6 8 10 12 14 16 18 20
SHDN PIN VOLTAGE (V)
5
TJ = –50°C
3.0
CURRENT LIMIT (A)
6
4
Current Limit
3.5
7
2
6
4.0
VSHDN = 20V
8
0
1764 G24
ADJ Pin Bias Current
ADJ PIN BIAS CURRENT (µA)
SHDN PIN INPUT CURRENT (µA)
7
1764 G23
SHDN Pin Input Current
2.5
2.0
1.5
4
TJ = 125°C
3
TJ = 25°C
2
1.0
1
0.5
1
0
–50 –25
8
1
0
–50 –25
125
3.0
9
IL = 3A
0.8
1764 G22
9
2.5
SHDN Pin Input Current
0.1
0
–50 –25
1.0
2.0
1.5
OUTPUT CURRENT (A)
10
0.9
0.7
0.5
0
1764 G21
1.0
IL = 1mA
0.8
10
0
10
SHDN Pin Threshold
(Off-to-On)
SHDN PIN THRESHOLD (V)
SHDN PIN THRESHOLD (V)
0.9
9
1764 G20
SHDN Pin Threshold
(On-to-Off)
1.0
8
SHDN PIN INPUT CURRENT (µA)
0
50
25
0
75
TEMPERATURE (°C)
100
125
1764 G25
0
– 50 – 25
0
75
50
25
TEMPERATURE (°C)
0
100
125
1756 G26
0
2
4 6 8 10 12 14 16 18 20
INPUT/OUTPUT DIFFERENTIAL (V)
1764 G27
1764fb
7
LT1764 Series
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Current Limit
Reverse Output Current
VIN = 7V
VOUT = 0V
CURRENT LIMIT (A)
5
4
3
2
1
5.0
REVERSE OUTPUT CURRENT (mA)
6
4.5
LT1764
4.0
LT1764-1.8
3.5
3.0
LT1764-2.5
LT1764-3.3
2.5
TJ = 25°C
VIN = 0V
CURRENT FLOWS
INTO OUTPUT PIN
VOUT = VADJ (LT1764)
VOUT = VFB
(LT1764-1.8/-2.5/-3.3)
2.0
1.5
1.0
0.5
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
0
125
0
1
2
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
9
1764 G28
1764 G29
Ripple Rejection
Reverse Output Current
80
VIN = 0V
0.9 VOUT = 1.21V (LT1764)
= 1.8V (LT1764-1.8)
V
0.8 OUT
VOUT = 2.5V (LT1764-2.5)
0.7 VOUT = 3.3V (LT1764-3.3)
70
RIPPLE REJECTION (dB)
REVERSE OUTPUT CURRENT (mA)
1.0
0.6
LT1764-1.8/-2.5/-3.3
0.5
0.4
0.3
LT1764
0.2
0.1
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
60
50
COUT = 100µF
TANTALUM +
10 × 1µF
CERAMIC
40
30
20
COUT = 10µF
IL = 1.5A
TANTALUM
10 VIN = VOUT(NOM) + 1V
+ 50mVRMS RIPPLE
0
100
100k
10
1k
10k
FREQUENCY (Hz)
Ripple Rejection
65
60
55
50
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
1764 G32
3.0
MINIMUM INPUT VOLTAGE (V)
RIPPLE REJECTION (dB)
LT1764 Minimum Input Voltage
IL = 1.5A
VIN = VOUT(NOM) + 1V
+ 0.5VP-P RIPPLE
AT f = 120Hz
70
1M
1764 G31
1764 G30
75
10
2.5
IL = 3A
2.0
IL = 1.5A
1.5
IL = 500mA
IL = 100mA
1.0
0.5
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
1764 G33
1764fb
8
LT1764 Series
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Load Regulation
Output Noise Spectral Density
OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz)
10
LOAD REGULATION (mV)
5
LT1764
0
–5
LT1764-1.8
–10
LT1764-2.5
–15
LT1764-3.3
–20
∆IL = 1mA TO 3A
VIN = 2.7V (LT1764)
VIN = VOUT(NOM) + 1V
(LT1764-1.8/-2.5/-3.3)
–25
–30
– 50 – 25
75
50
25
TEMPERATURE (°C)
100
0
125
1
COUT = 10µF
ILOAD = 3A
LT1764-3.3
LT1764-2.5
LT1764
LT1764-1.8
0.1
0.01
10
100
1k
10k
FREQUENCY (Hz)
1764 G35
1764 G34
RMS Output Noise vs Load Current
(10Hz to 100kHz)
40
COUT = 10µF
100k
LT1764-3.3 10Hz to 100kHz
Output Noise
LT1764-3.3
OUTPUT NOISE (µVRMS)
35
30
LT1764-2.5
VOUT
100µV/
DIV
25
LT1764-1.8
20
LT1764
15
10
COUT = 10µF
IL = 3A
5
0
0.0001
0.001
0.01
0.1
LOAD CURRENT (A)
1ms/DIV
1764 G37
10
1
1764 G36
0.1
0
VIN = 4.3V
CIN = 3.3µF TANTALUM
COUT = 10µF TANTALUM
–0.1
–0.2
OUTPUT VOLTAGE
DEVIATION (V)
0.2
LT1764-3.3 Transient Response
0.2
0.1
0
–0.1
VIN = 4.3V
CIN = 33µF
COUT = 100µF TANTALUM
+ 10 × 1µF CERAMIC
–0.2
1.00
0.75
0.50
0.25
0
0
2
4
6
8 10 12 14 16 18 20
TIME (µs)
1764 G38
LOAD CURRENT (A)
LOAD CURRENT (A)
OUTPUT VOLTAGE
DEVIATION (V)
LT1764-3.3 Transient Response
3
2
1
0
0
2
4
6
8 10 12 14 16 18 20
TIME (µs)
1764 G39
1764fb
9
LT1764 Series
U
U
U
PI FU CTIO S
(DD and TO-220/TSSOP)
SHDN (Pin 1/Pin 10): Shutdown. The SHDN pin is used to
put the LT1764 regulators into a low power shutdown
state. The output will be off when the SHDN pin is pulled
low. The SHDN pin can be driven either by 5V logic or
open-collector logic with a pull-up resistor. The pull-up
resistor is required to supply the pull-up current of the
open-collector gate, normally several microamperes, and
the SHDN pin current, typically 7µA. If unused, the SHDN
pin must be connected to VIN. The device will be in the low
power shutdown state if the SHDN pin is not connected.
OUT (Pin 4/Pins 3, 4, 5): Output. The output supplies
power to the load. A minimum output capacitor of 10µF is
required to prevent oscillations. Larger output capacitors
will be required for applications with large transient loads
to limit peak voltage transients. See the Applications
Information section for more information on output capacitance and reverse output characteristics.
SENSE (Pin 5/Pin 6): Sense. For fixed voltage versions of
the LT1764 (LT1764-1.8/LT1764-2.5/LT1764-3.3), the
SENSE pin is the input to the error amplifier. Optimum
regulation will be obtained at the point where the SENSE
pin is connected to the OUT pin of the regulator. In critical
applications, small voltage drops are caused by the resistance (RP) of PC traces between the regulator and the load.
These may be eliminated by connecting the SENSE pin to
the output at the load as shown in Figure 1 (Kelvin Sense
Connection). Note that the voltage drop across the external PC traces will add to the dropout voltage of the
regulator. The SENSE pin bias current is 600µA at the
nominal rated output voltage. The SENSE pin can be pulled
below ground (as in a dual supply system where the
regulator load is returned to a negative supply) and still
allow the device to start and operate.
IN (Pin 2/Pins 12, 13, 14): 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 battery-powered circuits. A bypass capacitor in the range of 1µF to
10µF is sufficient. The LT1764 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 will act as if there is a diode in series with its input.
There will be no reverse current flow into the regulator and
no reverse voltage will appear at the load. The device will
protect both itself and the load.
ADJ (Pin 5/Pin 6): Adjust. For the adjustable LT1764, this
is the input to the error amplifier. This pin is internally
clamped to ±7V. It has a bias current of 3µA which flows
into the pin. The ADJ pin voltage is 1.21V referenced to
ground and the output voltage range is 1.21V to 20V.
GND (Pin 3/Pins 1, 7, 8, 9, 16, 17): Ground. The exposed
pad (FE Package) is ground and must be soldered to the
PCB for rated thermal performance.
2
IN
OUT
4
RP
LT1764
+
VIN
1
SHDN
SENSE
GND
+
5
LOAD
3
RP
1764 F01
Figure 1. Kelvin Sense Connection
1764fb
10
LT1764 Series
U
W
U U
APPLICATIO S I FOR ATIO
The LT1764 series are 3A low dropout regulators optimized for fast transient response. The devices are capable
of supplying 3A at a dropout voltage of 340mV. The low
operating quiescent current (1mA) drops to less than 1µA
in shutdown. In addition to the low quiescent current, the
LT1764 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 LT1764-X acts like
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 20V
and still allow the device to start and operate.
Adjustable Operation
The adjustable version of the LT1764 has an output
voltage range of 1.21V to 20V. The output voltage is set by
the ratio of two external resistors as shown in Figure 2. The
device servos the output to maintain the voltage at the ADJ
pin at 1.21V referenced to ground. The current in R1 is
then equal to 1.21V/R1 and the current in R2 is the current
in R1 plus the ADJ pin bias current. The ADJ pin bias
current, 3µA at 25°C, flows through R2 into the ADJ pin.
The output voltage can be calculated using the formula in
Figure 2. The value of R1 should be less than 4.17k to
minimize errors in the output voltage caused by the ADJ
pin bias current. Note that in shutdown the output is turned
off and the divider current will be zero.
The adjustable device is tested and specified with the ADJ
pin tied to the OUT pin for an output voltage of 1.21V.
Specifications for output voltages greater than 1.21V will
IN
VIN
OUT
VOUT
+
R2
LT1764
ADJ
GND
R1
1764 F02
⎛ R2⎞
VOUT = 1.21V ⎜ 1 + ⎟ + (IADJ )(R2)
⎝ R1⎠
VADJ = 1.21V
IADJ = 3µA AT 25°C
OUTPUT RANGE = 1.21V TO 20V
Figure 2. Adjustable Operation
be proportional to the ratio of the desired output voltage to
1.21V: VOUT/1.21V. For example, load regulation for an
output current change of 1mA to 3A is – 3mV typical at
VOUT = 1.21V. At VOUT = 5V, load regulation is:
(5V/1.21V)(–3mV) = – 12.4mV
Output Capacitance and Transient Response
The LT1764 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 10µF with an ESR in
the range of 50mΩ to 3Ω 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 LT1764-X, will 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 across
temperature and applied voltage. The most common dielectrics used are specified with EIA temperature characteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and Y5V
dielectrics are good for providing high capacitances in a
small package, but they tend to have strong voltage and
temperature coefficients as shown in Figures 3 and 4.
When used with a 5V regulator, a 16V 10µF Y5V capacitor
can exhibit an effective value as low as 1µF to 2µF for the
DC bias voltage applied and 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. Care still must be exercised
when using X5R and X7R capacitors; the X5R and X7R
codes only specify operating temperature range and maximum capacitance change over temperature. Capacitance
change due to DC bias with X5R and X7R capacitors is
better than Y5V and Z5U capacitors, but can still be
significant enough to drop capacitor values below appropriate levels. Capacitor DC bias characteristics tend to
improve as component case size increases, but expected
capacitance at operating voltage should be verified.
1764fb
11
LT1764 Series
U
W
U U
APPLICATIO S I FOR ATIO
20
The protection is designed to provide some output current
at all values of input-to-output voltage up to the device
breakdown.
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
0
CHANGE IN VALUE (%)
X5R
–20
–40
–60
Y5V
–80
–100
0
2
14
8
6
4
10 12
DC BIAS VOLTAGE (V)
16
1764 F03
Figure 3. Ceramic Capacitor DC Bias Characteristics
The problem occurs with a heavy output load when the
input voltage is high and the output voltage is low. Common situations are immediately after the removal of a
short circuit or when the SHDN 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.
40
CHANGE IN VALUE (%)
20
X5R
0
–20
–40
Y5V
–60
–80
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
–100
–50 –25
50
25
75
0
TEMPERATURE (°C)
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 the 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 will not allow the
output voltage to recover. Other regulators, such as the
LT1085, also exhibit this phenomenon, so it is not unique
to the LT1764 series.
100
125
1764 F04
Figure 4. Ceramic Capacitor Temperature Characteristics
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.
Overload Recovery
Like many IC power regulators, the LT1764-X 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.
Output Voltage Noise
The LT1764 regulators have been designed to provide low
output voltage noise over the 10Hz to 100kHz bandwidth
while operating at full load. Output voltage noise is typically 50nV√Hz over this frequency bandwidth for the
LT1764 (adjustable version). For higher output voltages
(generated by using a resistor divider), the output voltage
noise will be gained up accordingly. This results in RMS
noise over the 10Hz to 100kHz bandwidth of 15µVRMS for
the LT1764 increasing to 37µVRMS for the LT1764-3.3.
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 LT1764-X. Power
supply ripple rejection must also be considered; the LT1764
regulators do not have unlimited power supply rejection
and will pass a small portion of the input noise through to
the output.
1764fb
12
LT1764 Series
U
U
W
U
APPLICATIONS INFORMATION
Table 2. FE Package, 16-Lead TSSOP
Thermal Considerations
The power handling capability of the device is limited
by the maximum rated junction temperature (125°C).
The power dissipated by the device is made up of two
components:
COPPER AREA
TOPSIDE*
BACKSIDE
BOARD AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
2500mm2
2500mm2
2500mm2
38°C/W
2
2
2
43°C/W
2500mm
2
2500mm
48°C/W
2500mm2
2500mm2
60°C/W
1000mm
225mm
2
2500mm
2
2500mm
1. Output current multiplied by the input/output voltage
differential: (IOUT)(VIN – VOUT), and
* Device is mounted on topside
2. GND pin current multiplied by the input voltage:
(IGND)(VIN).
T Package, 5-Lead TO-220
Thermal Resistance (Junction-to-Case) = 2.5°C/W
The GND pin current can be found using the GND Pin
Current curves in the Typical Performance Characteristics. Power dissipation will be equal to the sum of the two
components listed above.
Calculating Junction Temperature
The LT1764 series regulators have internal thermal limiting designed to protect the device during overload conditions. For continuous normal conditions, the maximum
junction temperature rating of 125°C must not be
exceeded. 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.
For surface mount devices, heat sinking is accomplished
by using the heat spreading capabilities of the PC board
and its copper traces. Surface mount heatsinks and plated
through-holes can also be used to spread the heat generated by power devices.
The following tables list thermal resistance for several
different board sizes and copper areas. All measurements
were taken in still air on 1/16" FR-4 board with one ounce
copper.
Table 1. Q Package, 5-Lead DD
COPPER AREA
TOPSIDE*
BACKSIDE
BOARD AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
2500mm2
2500mm2
2500mm2
23°C/W
2
2
2
25°C/W
33°C/W
1000mm
2500mm
2500mm
125mm2
2500mm2
2500mm2
100mm2
Example: Given an output voltage of 3.3V, an input voltage
range of 4V to 6V, an output current range of 0mA to
500mA and a maximum ambient temperature of 50°C,
what will the maximum junction temperature be?
The power dissipated by the device will be equal to:
IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX))
where,
IOUT(MAX) = 500mA
VIN(MAX) = 6V
IGND at (IOUT = 500mA, VIN = 6V) = 10mA
So,
P = 500mA(6V – 3.3V) + 10mA(6V) = 1.41W
Using a DD package, the thermal resistance will be in the
range of 23°C/W to 33°C/W depending on the copper
area. So the junction temperature rise above ambient will
be approximately equal to:
1.41W(28°C/W) = 39.5°C
The maximum junction temperature will then be equal to
the maximum junction temperature rise above ambient
plus the maximum ambient temperature or:
TJMAX = 50°C + 39.5°C = 89.5°C
* Device is mounted on topside
1764fb
13
LT1764 Series
U
W
U
U
APPLICATIONS INFORMATION
Protection Features
The LT1764 regulators incorporate several protection
features which make them ideal for use in battery-powered
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 will withstand reverse voltages of
20V. Current flow into the device will be limited to less than
1mA and no negative voltage will appear at the output. The
device will protect both itself and the load. This provides
protection against batteries which can be plugged in
backward.
The output of the LT1764-X 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
20V. For fixed voltage versions, the output will act like a
large resistor, typically 5k or higher, limiting current flow
to typically less than 600µA. For adjustable versions, the
output will act like an open circuit; no current will flow out
of the pin. If the input is powered by a voltage source, the
output will source the short-circuit current of the device
and will protect itself by thermal limiting. In this case,
grounding the SHDN pin will turn off the device and stop
the output from sourcing the short-circuit current.
The ADJ pin of the adjustable device can be pulled above
or below ground by as much as 7V without damaging the
device. If the input is left open circuit or grounded, the ADJ
pin will act like an open circuit when pulled below ground
and like a large resistor (typically 5k) in series with a diode
when pulled above ground.
In situations where the ADJ pin is connected to a resistor
divider that would pull the ADJ pin above its 7V clamp
voltage if the output is pulled high, the ADJ pin input
current must be limited to less than 5mA. For example, a
resistor divider is used to provide a regulated 1.5V output
from the 1.21V reference when the output is forced to 20V.
The top resistor of the resistor divider must be chosen to
limit the current into the ADJ pin to less than 5mA when the
ADJ pin is at 7V. The 13V difference between OUT and ADJ
pins divided by the 5mA maximum current into the ADJ pin
yields a minimum top resistor value of 2.6k.
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. Current flow back into the output will follow
the curve shown in Figure 5.
When the IN pin of the LT1764-X is forced below the OUT
pin or the OUT pin is pulled above the IN pin, input current
will typically drop to less than 2µA. 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 SHDN pin will have no effect on the reverse output
current when the output is pulled above the input.
REVERSE OUTPUT CURRENT (mA)
5.0
4.5
TJ = 25°C
VIN = OV
CURRENT FLOWS INTO
OUTPUT PIN
VOUT = VADJ (LT1764)
VOUT = VFB (LT1764-1.8,
LT1764-2.5, LT1764-3.3)
LT1764
4.0
3.5
LT1764-1.8
3.0
2.5
2.0
LT1764-2.5
1.5
1.0
LT1764-3.3
0.5
0
0
1
2
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
9
10
1764 F05
Figure 5. Reverse Output Current
1764fb
14
LT1764 Series
U
TYPICAL APPLICATIO S
SCR Preregulator Provides Efficiency Over Line Variations
L1
500µH
NTE5437
LT1764-3.3
L2
90V AC
TO 140V AC
+
1N4148
10V AC
AT 115VIN
IN
SHDN
10000µF
OUT
FB
22µF
GND
1k
VOUT
3.3V
3A
+
34k*
10V AC
AT 115VIN
12.1k*
NTE5437
1N4002
1N4002
V+
“SYNC”
1N4002
TO
ALL “V +”
POINTS
2.4k
+
+
22µF
750Ω
1N4148
200k
C1A
1/2 LT1018
0.1µF
–
V+
0.033µF
750Ω
V+
+
C1B
1/2 LT1018
+
1N4148
A1
LT1006
–
L1: COILTRONICS CTX500-2-52
L2: STANCOR P-8560
*1% FILM RESISTOR
10k
10k
10k
V+
–
1µF
V+
LT1004
1.2V
1764 TA03
1764fb
15
LT1764 Series
U
TYPICAL APPLICATIO S
Adjustable Current Source
R5
0.01Ω
+
VIN > 2.7V
C1
10µF
LT1004-1.2
IN
OUT
LT1764-1.8
SHDN
FB
R1
1k
R2
40.2k
R4
2.2k
R6
2.2k
LOAD
R8
100k
GND
R3
2k
C3
1µF
R7
470Ω
ADJUST R1 FOR 0A TO 3A
CONSTANT CURRENT
2
–
3
+
8
1/2 LT1366
C2
3.3µF
1
4
1764 TA04
1764fb
16
LT1764 Series
U
PACKAGE DESCRIPTION
Q Package
5-Lead Plastic DD Pak
(LTC DWG # 05-08-1461)
.256
(6.502)
.060
(1.524)
TYP
.060
(1.524)
.390 – .415
(9.906 – 10.541)
.165 – .180
(4.191 – 4.572)
.045 – .055
(1.143 – 1.397)
15° TYP
.060
(1.524)
.183
(4.648)
+.008
.004 –.004
+0.203
0.102 –0.102
.059
(1.499)
TYP
.330 – .370
(8.382 – 9.398)
(
)
.095 – .115
(2.413 – 2.921)
.075
(1.905)
.300
(7.620)
+.012
.143 –.020
+0.305
3.632 –0.508
(
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
.067
(1.702)
.028 – .038 BSC
(0.711 – 0.965)
TYP
)
Q(DD5) 0502
.420
.276
.080
.420
.050 ± .012
(1.270 ± 0.305)
.013 – .023
(0.330 – 0.584)
.325
.350
.205
.565
.565
.320
.090
.090
.067
.042
RECOMMENDED SOLDER PAD LAYOUT
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
.067
.042
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
1764fb
17
LT1764 Series
U
PACKAGE DESCRIPTION
T Package
5-Lead Plastic TO-220 (Standard)
(LTC DWG # 05-08-1421)
0.390 – 0.415
(9.906 – 10.541)
0.165 – 0.180
(4.191 – 4.572)
0.147 – 0.155
(3.734 – 3.937)
DIA
0.045 – 0.055
(1.143 – 1.397)
0.230 – 0.270
(5.842 – 6.858)
0.460 – 0.500
(11.684 – 12.700)
0.570 – 0.620
(14.478 – 15.748)
0.330 – 0.370
(8.382 – 9.398)
0.620
(15.75)
TYP
0.700 – 0.728
(17.78 – 18.491)
SEATING PLANE
0.152 – 0.202
0.260 – 0.320 (3.861 – 5.131)
(6.60 – 8.13)
0.095 – 0.115
(2.413 – 2.921)
0.155 – 0.195*
(3.937 – 4.953)
0.013 – 0.023
(0.330 – 0.584)
BSC
0.067
(1.70)
0.028 – 0.038
(0.711 – 0.965)
0.135 – 0.165
(3.429 – 4.191)
* MEASURED AT THE SEATING PLANE
T5 (TO-220) 0399
1764fb
18
LT1764 Series
U
PACKAGE DESCRIPTION
FE Package
16-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1663)
Exposed Pad Variation BB
4.90 – 5.10*
(.193 – .201)
3.58
(.141)
3.58
(.141)
16 1514 13 12 1110
6.60 ±0.10
9
2.94
(.116)
4.50 ±0.10
2.94 6.40
(.116) (.252)
BSC
SEE NOTE 4
0.45 ±0.05
1.05 ±0.10
0.65 BSC
1 2 3 4 5 6 7 8
RECOMMENDED SOLDER PAD LAYOUT
4.30 – 4.50*
(.169 – .177)
0.09 – 0.20
(.0035 – .0079)
0.50 – 0.75
(.020 – .030)
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
MILLIMETERS
2. DIMENSIONS ARE IN
(INCHES)
3. DRAWING NOT TO SCALE
0.25
REF
1.10
(.0433)
MAX
0° – 8°
0.65
(.0256)
BSC
0.195 – 0.30
(.0077 – .0118)
TYP
0.05 – 0.15
(.002 – .006)
FE16 (BB) TSSOP 0204
4. RECOMMENDED MINIMUM PCB METAL SIZE
FOR EXPOSED PAD ATTACHMENT
*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.150mm (.006") PER SIDE
1764fb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LT1764 Series
U
TYPICAL APPLICATIO
Paralleling of Regulators for Higher Output Current
R1
0.01Ω
+
IN
OUT
LT1764-3.3
SHDN
FB
C1
100µF
VIN > 3.7V
+
3.3V
6A
C2
22µF
GND
R2
0.01Ω
IN
SHDN
OUT
LT1764
SHDN
R7
4.12k
GND
R3
2.2k
R4
2.2k
3
+
8
–
4
R5
1k
1
1/2 LT1366
2
R6
6.65k
ADJ
C3
0.01µF
1764 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1120
125mA Low Dropout Regulator with 20µA IQ
Includes 2.5V Reference and Comparator
LT1121
150mA Micropower Low Dropout Regulator
30µA IQ, SOT-223 Package
LT1129
700mA Micropower Low Dropout Regulator
50µA Quiescent Current
LT1175
500mA Negative Low Dropout Micropower Regulator
45µA IQ, 0.26V Dropout Voltage, SOT-223 Package
LT1374
4.5A, 500kHz Step-Down Converter
4.5A, 0.07Ω Internal Switch, SO-8 Package
LT1521
300mA Low Dropout Micropower Regulator with Shutdown
15µA IQ, Reverse Battery Protection
LT1529
3A Low Dropout Regulator with 50µA IQ
500mV Dropout Voltage
LT1573
UltraFastTM Transient Response Low Dropout Regulator
Drives External PNP
LT1575
UltraFast Transient Response Low Dropout Regulator
Drives External N-Channel MOSFET
LT1735
Synchronous Step-Down Converter
High Efficiency, OPTI-LOOP® Compensation
LT1761 Series
100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23
20µA Quiescent Current, 20µVRMS Noise, SOT-23 Package
LT1762 Series
150mA, Low Noise, LDO Micropower Regulators
25µA Quiescent Current, 20µVRMS Noise, MSOP Package
LT1763 Series
500mA, Low Noise, LDO Micropower Regulators
30µA Quiescent Current, 20µVRMS Noise, SO-8 Package
LT1962
300mA, Low Noise, LDO Micropower Regulator
20µVRMS Noise, MSOP Package
LT1963
1.5A, Low Noise, Fast Transient Response LDO
40µVRMS Noise, SOT-223 Package
UltraFast is a trademark of Linear Technology Corporation.
OPTI-LOOP is a registered trademark of Linear Technology Corporation.
1764fb
20
Linear Technology Corporation
LT 1205 REV B • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2005