LT1763CS8#TRPBF [Linear]
LT1763 - 500mA, Low Noise, LDO Micropower Regulators; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C;
| 型号： | LT1763CS8#TRPBF |
| 厂家： | 
Linear |
| 描述： | LT1763 - 500mA, Low Noise, LDO Micropower Regulators; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C 线性稳压器IC 调节器 电源电路 光电二极管 输出元件 |
| 文件： | 总16页 (文件大小：280K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1763 Series
500mA, Low Noise, LDO
Micropower Regulators
U
FEATURES
DESCRIPTIO
The LT®1763 series are micropower, low noise, low
dropout regulators. The devices are capable of supplying
500mAofoutputcurrentwithadropoutvoltageof300mV.
Designed for use in battery-powered systems, the low
30µA quiescent current makes them an ideal choice.
Quiescent current is well controlled; it does not rise in
dropout as it does with many other regulators.
■
Low Noise: 20µVRMS (10Hz to 100kHz)
■
Output Current: 500mA
■
Low Quiescent Current: 30µA
■
Wide Input Voltage Range: 1.8V to 20V
■
Low Dropout Voltage: 300mV
■
Very Low Shutdown Current: < 1µA
■
■
■
■
■
No Protection Diodes Needed
Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3V, 3.3V, 5V
Adjustable Output from 1.22V to 20V
Stable with 3.3µF Output Capacitor
Stable with Aluminum, Tantalum or
Ceramic Capacitors
A key feature of the LT1763 regulators is low output noise.
With the addition of an external 0.01µF bypass capacitor,
output noise drops to 20µVRMS over a 10Hz to 100kHz
bandwidth. The LT1763 regulators are stable with output
capacitors as low as 3.3µF. Small ceramic capacitors can
be used without the series resistance required by other
regulators.
■
■
■
■
Reverse Battery Protection
No Reverse Current
Overcurrent and Overtemperature Protected
8-Lead SO Package
Internal protection circuitry includes reverse battery pro-
tection, current limiting, thermal limiting and reverse
current protection. The parts come in fixed output volt-
ages of 1.5V, 1.8V, 2.5V, 3V, 3.3V and 5V, and as an
adjustable device with a 1.22V reference voltage. The
LT1763 regulators are available in the 8-lead SO package.
U
APPLICATIO S
■
Cellular Phones
■
Battery-Powered Systems
■
Noise-Sensitive Instrumentation Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
U
TYPICAL APPLICATIO
Dropout Voltage
400
350
300
250
200
150
100
50
3.3V Low Noise Regulator
3.3V AT 500mA
IN
OUT
V
20µV
NOISE
IN
RMS
+
3.7V TO
20V
1µF
SENSE
10µF
LT1763-3.3
0.01µF
1763 TA01
SHDN
GND
BYP
0
0
100
200
300
400
500
OUTPUT CURRENT (mA)
1763 TA02
1763fa
1
LT1763 Series
W W
U W
W U
ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
TOP VIEW
IN Pin Voltage........................................................ ±20V
OUT Pin Voltage .................................................... ±20V
Input to Output Differential Voltage ....................... ±20V
SENSE Pin Voltage ............................................... ±20V
ADJ Pin Voltage ...................................................... ±7V
BYP Pin Voltage.................................................... ±0.6V
SHDN Pin Voltage................................................. ±20V
Output Short-Circut Duration.......................... Indefinite
Operating Junction Temperature Range
*PIN 2: SENSE FOR LT1763-1.5/
OUT
SENSE/ADJ*
GND
1
2
3
4
8
7
6
5
IN
LT1763-1.8/LT1763-2.5/
LT1763-3/LT1763-3.3/LT1763-5
ADJ FOR LT1763
GND
GND
SHDN
TJMAX = 150°C, θJA = 70°C/ W,
θJC = 35°C/ W
BYP
SEE THE APPLICATIONS
INFORMATION SECTION.
S8 PACKAGE
8-LEAD PLASTIC SO
S8 PART MARKING
ORDER PART NUMBER
(Note 2) ............................................ –40°C to 125°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
LT1763CS8
1763
17633
LT1763CS8-3
LT1763CS8-3.3
LT1763CS8-5
LT1763CS8-1.5
LT1763CS8-1.8
LT1763CS8-2.5
176315 176333
176318 17635
176325
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2)
PARAMETER
CONDITIONS
= 500mA (Notes 3, 11)
MIN
TYP
MAX
UNITS
Minimum Operating Voltage
I
●
●
●
●
●
●
●
●
1.8
2.3
V
LOAD
Regulated Output Voltage
(Note 4)
LT1763-1.5
LT1763-1.8
LT1763-2.5
LT1763-3
LT1763-3.3
LT1763-5
LT1763
V
= 2V, I
= 1mA
LOAD
1.485
1.462
1.5
1.5
1.515
1.538
V
V
IN
2.5V < V < 20V, 1mA < I
< 500mA
< 500mA
< 500mA
IN
LOAD
LOAD
LOAD
V
= 2.3V, I
= 1mA
LOAD
1.782
1.755
1.8
1.8
1.818
1.845
V
V
IN
2.8V < V < 20V, 1mA < I
IN
V
= 3V, I
= 1mA
LOAD
2.475
2.435
2.5
2.5
2.525
2.565
V
V
IN
3.5V < V < 20V, 1mA < I
IN
V
= 3.5V, I
IN
= 1mA
LOAD
2.970
2.925
3
3
3.030
3.075
V
V
IN
4V < V < 20V, 1mA < I
< 500mA
LOAD
V
= 3.8V, I
= 1mA
LOAD
3.267
3.220
3.3
3.3
3.333
3.380
V
V
IN
4.3V < V < 20V, 1mA < I
< 500mA
LOAD
IN
V
= 5.5V, I
IN
= 1mA
LOAD
4.950
4.875
5
5
5.050
5.125
V
V
IN
6V < V < 20V, 1mA < I
< 500mA
LOAD
ADJ Pin Voltage
(Notes 3, 4)
V
= 2V, I
= 1mA
LOAD
1.208
1.190
1.22
1.22
1.232
1.250
V
V
IN
2.22V < V < 20V, 1mA < I
< 500mA
LOAD
IN
Line Regulation
LT1763-1.5
LT1763-1.8
LT1763-2.5
LT1763-3
∆V = 2V to 20V, I
IN
= 1mA
●
●
●
●
●
●
●
1
1
1
1
1
1
1
5
5
5
5
5
5
5
mV
mV
mV
mV
mV
mV
mV
IN
LOAD
∆V = 2.3V to 20V, I
= 1mA
LOAD
∆V = 3V to 20V, I
= 1mA
IN
LOAD
∆V = 3.5V to 20V, I
= 1mA
IN
LOAD
LOAD
LOAD
LT1763-3.3
LT1763-5
∆V = 3.8V to 20V, I
= 1mA
= 1mA
IN
∆V = 5.5V to 20V, I
IN
LT1763 (Note 3) ∆V = 2V to 20V, I
= 1mA
IN
LOAD
Load Regulation
LT1763-1.5
LT1763-1.8
LT1763-2.5
V
V
= 2.5V, ∆I
= 2.5V, ∆I
= 1mA to 500mA
= 1mA to 500mA
3
4
5
8
mV
mV
IN
IN
LOAD
LOAD
●
●
●
15
V
V
= 2.8V, ∆I
= 2.8V, ∆I
= 1mA to 500mA
= 1mA to 500mA
9
18
mV
mV
IN
IN
LOAD
LOAD
V
V
= 3.5V, ∆I
= 3.5V, ∆I
= 1mA to 500mA
= 1mA to 500mA
12
25
mV
mV
IN
IN
LOAD
LOAD
1763fa
2
LT1763 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
Load Regulation
LT1763-3
V
V
= 4V, ∆I
= 4V, ∆I
= 1mA to 500mA
= 1mA to 500mA
7
15
30
mV
mV
IN
IN
LOAD
LOAD
●
●
●
●
●
●
●
●
LT1763-3.3
LT1763-5
V
V
= 4.3V, ∆I
= 4.3V, ∆I
= 1mA to 500mA
= 1mA to 500mA
7
17
33
mV
mV
IN
IN
LOAD
LOAD
V
V
= 6V, ∆I
= 6V, ∆I
= 1mA to 500mA
= 1mA to 500mA
12
25
50
mV
mV
IN
IN
LOAD
LOAD
LT1763 (Note 3)
V
V
= 2.3V, ∆I
= 2.3V, ∆I
= 1mA to 500mA
= 1mA to 500mA
2
6
12
mV
mV
IN
IN
LOAD
LOAD
Dropout Voltage
I
I
= 10mA
= 10mA
0.13
0.17
0.20
0.30
0.19
0.25
V
V
LOAD
LOAD
V
= V
OUT(NOMINAL)
IN
(Notes 5, 6, 11)
I
I
= 50mA
= 50mA
0.22
0.32
V
V
LOAD
LOAD
I
I
= 100mA
= 100mA
0.24
0.34
V
V
LOAD
LOAD
I
I
= 500mA
= 500mA
0.35
0.45
V
V
LOAD
LOAD
GND Pin Current
I
I
I
I
I
I
= 0mA
●
●
●
●
●
●
30
65
1.1
2
75
120
1.6
3
µA
µA
mA
mA
mA
mA
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
V
= V
= 1mA
IN
OUT(NOMINAL)
(Notes 5, 7)
= 50mA
= 100mA
= 250mA
= 500mA
5
8
11
16
Output Voltage Noise
ADJ Pin Bias Current
Shutdown Threshold
C
= 10µF, C
= 0.01µF, I
= 500mA, BW = 10Hz to 100kHz
20
30
µV
RMS
OUT
BYP
LOAD
(Notes 3, 8)
100
2
nA
V
V
= Off to On
= On to Off
●
●
0.8
0.65
V
V
OUT
OUT
0.25
SHDN Pin Current
(Note 9)
V
V
= 0V
= 20V
0.1
1
µA
µA
SHDN
SHDN
Quiescent Current in Shutdown
Ripple Rejection
V
V
= 6V, V
= 0V
SHDN
0.1
65
1
µA
IN
– V
= 1.5V (Avg), V
= 0.5V , f = 120Hz,
P-P RIPPLE
50
dB
IN
OUT
RIPPLE
I
= 500mA
LOAD
Current Limit
V
V
= 7V, V
= 0V
700
mA
mA
IN
IN
OUT
OUT(NOMINAL)
= V
+ 1V, ∆V
= –0.1V
●
●
520
OUT
Input Reverse Leakage Current
V
= –20V, V
= 0V
OUT
1
mA
IN
Reverse Output Current
(Note 10)
LT1763-1.5
LT1763-1.8
LT1763-2.5
LT1763-3
V
V
V
V
V
V
V
= 1.5V, V < 1.5V
10
10
10
10
10
10
5
20
20
20
20
20
20
10
µA
µA
µA
µA
µA
µA
µA
OUT
OUT
OUT
OUT
OUT
OUT
OUT
IN
= 1.8V, V < 1.8V
IN
= 2.5V, V < 2.5V
IN
= 3V, V < 3V
IN
LT1763-3.3
LT1763-5
= 3.3V, V < 3.3V
IN
= 5V, V < 5V
IN
LT1763 (Note 3)
= 1.22V, V < 1.22V
IN
all possible combinations of input voltage and output current. When
Note 1: Absolute Maximum Ratings are those values beyond which the life
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.
of a device may be impaired.
Note 2: The LT1763 regulators are tested and specified under pulse load
conditions such that T ≈ T . The LT1763 is 100% tested at T = 25°C.
J
A
A
Note 5: To satisfy requirements for minimum input voltage, the LT1763
(adjustable version) is tested and specified for these conditions with an
external resistor divider (two 250k resistors) for an output voltage of
2.44V. The external resistor divider will add a 5µA DC load on the output.
Performance at –40°C and 125°C is assured by design, characterization
and correlation with statistical process controls.
Note 3: The LT1763 (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
1763fa
3
LT1763 Series
ELECTRICAL CHARACTERISTICS
Note 6: Dropout voltage is the minimum input to output voltage differential
Note 9: SHDN pin current flows into the SHDN pin.
needed to maintain regulation at a specified output current. In dropout, the
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.
output voltage will be equal to: V – V
.
IN
DROPOUT
Note 7: GND pin current is tested with V = V
or V = 2.3V
IN
IN
OUT(NOMINAL)
(whichever is greater) and a current source load. This means the device is
tested while operating in its dropout region. This is the worst-case GND
pin current. The GND pin current will decrease slightly at higher input
voltages.
Note 11: For the LT1763, LT1763-1.5 and LT1763-1.8 dropout voltage will
be limited by the minimum input voltage specification under some output
voltage/load conditions. See the curve of Minimum Input Voltage in the
Typical Performance Characteristics.
Note 8: ADJ pin bias current flows into the ADJ pin.
U W
TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage
Typical Dropout Voltage
Guaranteed Dropout Voltage
500
450
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
= TEST POINTS
I
= 500mA
L
I
L
= 250mA
T
J
= 125°C
T
≤ 125°C
≤ 25°C
I
L
= 100mA
J
T
J
T
J
= 25°C
I
= 1mA
L
I
L
= 10mA
I
L
= 50mA
0
0
0
–50
0
25
50
75 100 125
–25
200
200
250 300 350 400 450 500
0
50 100 150
250 300 350 400 450 500
0
50 100 150
TEMPERATURE (°C)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
1763 G03
1763 G01
1763 G02
LT1763-1.5
Output Voltage
LT1763-1.8
Output Voltage
Quiescent Current
1.84
1.83
1.82
1.81
1.80
1.79
1.78
1.77
1.76
1.528
1.521
1.514
1.507
1.500
1.493
1.486
1.479
1.472
50
45
40
35
30
25
20
15
10
5
I
= 1mA
I
= 1mA
L
L
V
= V
IN
SHDN
V
= 6V
IN
L
L
R = ∞, I = 0 (LT1763-1.5/-1.8/-2.5/-3/-3.3/-5)
L
R = 250k, I = 5µA (LT1763)
L
0
–25
0
25
50
75
125
–50
100
–25
0
25
50
75
125
–25
0
25
50
75
125
–50
100
–50
100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1763 G51
1763 G04
1763 G50
1763fa
4
LT1763 Series
U W
TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-3.3
Output Voltage
LT1763-2.5
Output Voltage
LT1763-3
Output Voltage
3.060
3.045
3.030
3.015
3.000
2.985
2.970
2.955
2.940
2.54
2.53
2.52
2.51
2.50
2.49
2.48
2.47
2.46
3.360
3.345
3.330
3.315
3.300
3.285
3.270
3.255
3.240
I
= 1mA
I
= 1mA
I = 1mA
L
L
L
–25
0
25
50
75
125
–50
100
–25
0
25
50
75
125
–25
0
25
50
75
125
–50
100
–50
100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1763 G06
1763 G05
1763 G07
LT1763-5
Output Voltage
LT1763
ADJ Pin Voltage
LT1763-1.5
Quiescent Current
5.100
5.075
5.050
5.025
5.000
4.975
4.950
4.925
4.900
1.240
250
225
200
175
150
125
100
75
I
L
= 1mA
I = 1mA
L
T = 25°C
J
L
1.235
1.230
1.225
1.220
1.215
1.210
1.205
1.200
R
= ∞
50
V
= V
IN
SHDN
25
V
= 0V
6
SHDN
0
–25
0
25
50
75
125
–25
0
25
50
75
125
–50
100
–50
100
0
1
2
3
4
5
7
8
9
10
TEMPERATURE (°C)
TEMPERATURE (°C)
INPUT VOLTAGE (V)
1763 G08
1763 G09
1763 G52
LT1763-1.8
Quiescent Current
LT1763-2.5
Quiescent Current
LT1763-3
Quiescent Current
250
225
200
175
150
125
100
75
250
225
200
175
150
125
100
75
250
225
200
175
150
125
100
75
T = 25°C
L
T = 25°C
L
T = 25°C
J
R = ∞
L
J
J
R
= ∞
R
= ∞
50
50
50
V
= V
V
= V
V
= V
SHDN IN
SHDN
IN
SHDN
IN
25
25
25
V
= 0V
6
V
= 0V
8
V
SHDN
= 0V
8
SHDN
5
SHDN
0
0
0
0
1
2
3
4
7
8
9
10
0
1
2
3
4
5
6
7
9
10
0
1
2
3
4
5
6
7
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1763 G53
1763 G10
1763 G11
1763fa
5
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
U W
LT1763
Quiescent Current
LT1763-3.3
Quiescent Current
LT1763-5
Quiescent Current
40
35
30
25
20
15
10
5
250
225
200
175
150
125
100
75
250
225
200
175
150
125
100
75
T = 25°C
L
T = 25°C
L
T = 25°C
L
J
R
J
R
J
R
= 250k
= ∞
= ∞
V
= V
IN
SHDN
50
50
V
= V
IN
V
= V
IN
SHDN
SHDN
25
25
V
= 0V
V
= 0V
8
V
= 0V
8
SHDN
SHDN
SHDN
0
0
0
0
2
4
6
8
10 12 14 16 18 20
0
1
2
3
4
5
6
7
9
10
0
1
2
3
4
5
6
7
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1763 G14
1763 G12
1763 G13
LT1763-1.5
GND Pin Current
LT1763-1.8
GND Pin Current
LT1763-2.5
GND Pin Current
1200
1000
800
600
400
200
0
1200
1000
800
600
400
200
0
1200
1000
800
600
400
200
0
R
L
= 50Ω
L
R
L
= 36Ω
R
L
= 30Ω
L
I
= 50mA*
L
I
= 50mA*
I
= 50mA*
T = 25°C
T = 25°C
T = 25°C
J
V
J
V
J
V
= V
= V
= V
IN
SHDN
OUT
IN
SHDN
OUT
IN
SHDN
OUT
*FOR V
= 2.5V
*FOR V
= 1.5V
*FOR V
= 1.8V
R = 250Ω
L
R
I
= 150Ω
= 10mA*
R
L
= 180Ω
L
L
I
= 10mA*
= 2.5k
L
L
I
= 10mA*
L
R
= 1.5k
= 1mA*
R
I
R
I
= 1.8k
L
L
I
= 1mA*
= 1mA*
L
L
L
4
0
1
2
3
5
6
7
8
9
10
4
4
0
1
2
3
5
6
7
8
9
10
0
1
2
3
5
6
7
8
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1763 G15
1763 G54
1763 G55
LT1763-3.3
GND Pin Current
LT1763-5
GND Pin Current
LT1763-3
GND Pin Current
1200
1000
800
600
400
200
0
1200
1000
800
600
400
200
0
1200
1000
800
600
400
200
0
R
L
= 60Ω
R
L
= 66Ω
L
R
I
= 100Ω
L
L
L
I
= 50mA*
I
= 50mA*
= 50mA*
T = 25°C
T = 25°C
T = 25°C
J
J
V
J
V
= V
= V
V = V
IN SHDN
IN
SHDN
OUT
IN
SHDN
OUT
*FOR V
= 3V
*FOR V
= 3.3V
*FOR V
= 5V
OUT
R
I
= 500Ω
R
I
= 300Ω
R
I
= 330Ω
L
L
L
L
L
L
= 10mA*
= 10mA*
= 10mA*
R
L
= 3k
R
L
= 3.3k
L
R
L
= 5k
L
= 1mA*
L
I
= 1mA*
I
= 1mA*
I
4
0
1
2
3
4
6
7
8
9
10
0
1
2
3
4
6
7
8
9
10
0
1
2
3
5
6
7
8
9
10
5
5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1763 G16
1763 G17
1763 G18
1763fa
6
LT1763 Series
U W
TYPICAL PERFORMANCE CHARACTERISTICS
LT1763-1.8
GND Pin Current
LT1763
GND Pin Current
LT1763-1.5
GND Pin Current
1200
1000
800
600
400
200
0
12
10
8
12
10
8
T = 25°C
T = 25°C
J
J
V
= V
V = V
IN SHDN
IN
SHDN
OUT
R
L
= 24.4Ω
L
*FOR V
= 1.5V
*FOR V
= 1.8V
OUT
I
= 50mA*
R
= 3Ω
L
R
L
= 3.6Ω
L
I
= 500mA*
L
I
= 500mA*
T = 25°C
J
V
= V
R
L
= 6Ω
R
L
= 5Ω
IN
SHDN
OUT
L
L
6
6
*FOR V
= 1.22V
I
= 300mA*
I
= 300mA*
R
L
= 122Ω
= 10mA*
L
4
4
I
R
L
= 15Ω
R
= 18Ω
L
L
I
= 100mA*
I
L
= 100mA*
R
I
= 1.22k
= 1mA*
2
2
L
L
0
0
4
4
4
0
1
2
3
5
6
7
8
9
10
0
1
2
3
5
6
7
8
9
10
0
1
2
3
5
6
7
8
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1763 G19
1763 G56
1763 G57
LT1763-2.5
LT1763-3
GND Pin Current
LT1763-3.3
GND Pin Current
GND Pin Current
12
10
8
12
10
8
12
10
8
T = 25°C
T = 25°C
J
T = 25°C
J
J
V
= V
V = V
IN SHDN
V
= V
IN
SHDN
IN
SHDN
*FOR V
= 3V
*FOR V
= 3.3V
*FOR V
= 2.5V
OUT
OUT
OUT
R
= 5Ω
L
R
= 6Ω
R = 6.6Ω
L
L
I
= 500mA*
L
I
= 500mA*
I = 500mA*
L
L
6
R
L
= 10Ω
6
6
R = 11Ω
L
L
L
R
L
= 8.33Ω
L
I
= 300mA*
I
= 300mA*
I
= 300mA*
4
4
4
R
L
= 30Ω
R = 33Ω
L
I = 100mA*
L
R
L
= 25Ω
L
L
I
= 100mA*
I
= 100mA*
2
2
2
0
0
0
4
4
0
1
2
3
5
6
7
8
9
10
0
1
2
3
5
6
7
8
9
10
4
0
1
2
3
5
6
7
8
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1763 G21
1763 G22
1763 G20
LT1763-5
GND Pin Current
LT1763
GND Pin Current
GND Pin Current vs ILOAD
12
10
8
12
10
8
12
10
8
T = 25°C
T = 25°C
J
J
V
IN
= V
+ 1V
OUT(NOMINAL)
V
= V
V = V
IN SHDN
IN
SHDN
R
L
= 10Ω
L
*FOR V
= 5V
*FOR V
= 1.22V
OUT
I
= 500mA*
OUT
R
L
= 2.44Ω
L
I
= 500mA*
R
L
= 16.7Ω
L
R = 4.07Ω
L
L
6
6
6
I
= 300mA*
I
= 300mA*
4
4
4
R
L
= 12.2Ω
R
L
= 50Ω
L
L
I
= 100mA*
I
= 100mA*
2
2
2
0
0
0
4
0
1
2
3
5
6
7
8
9
10
4
200
250 300 350 400 450 500
0
1
2
3
5
6
7
8
9
10
0
50 100 150
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
1763 G23
1763 G24
1763 G25
1763fa
7
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
U W
SHDN Pin Threshold
(On-to-Off)
SHDN Pin Threshold
(Off-to-On)
SHDN Pin Input Current
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
I
= 1mA
L
I
= 500mA
L
I
= 1mA
L
–50
0
25
50
75 100 125
0
1
2
3
4
6
7
8
9
10
50
75 100 125
–25
5
–50
0
25
–25
TEMPERATURE (°C)
TEMPERATURE (°C)
SHDN PIN VOLTAGE (V)
1763 G27
1763 G28
1763 G26
ADJ Pin Bias Current
Current Limit
SHDN Pin Input Current
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
140
120
100
80
V
= 0V
V
= 20V
OUT
SHDN
60
40
20
0
0
2
3
4
5
6
7
1
–25
0
25
50
75
125
–50
0
25
50
75
125
–50
100
100
–25
INPUT VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
1763 G31
1763 G29
1763 G30
Current Limit
Reverse Output Current
Reverse Output Current
20
18
16
14
12
10
8
1.2
1.0
0.8
0.6
0.4
0.2
0
100
90
80
70
60
50
40
30
20
10
0
V
V
V
V
V
V
V
= 0V, V
= 1.22V (LT1763)
OUT
IN
V
V
= 7
OUT
T = 25°C, V = 0V
IN
J
IN
LT1763-1.5
= 1.5V (LT1763-1.5)
= 1.8V (LT1763-1.8)
= 2.5V (LT1763-2.5)
= 3V (LT1763-3)
OUT
OUT
OUT
OUT
OUT
OUT
= 0V
CURRENT FLOWS
INTO OUTPUT PIN
V
OUT
= V
ADJ
(LT1763)
= 3.3V (LT1763-3.3)
= 5V (LT1763-5)
LT1763
LT1763-1.8
LT1763-2.5
LT1763-3
LT1763-1.5/-1.8/
-2.5/-3/-3.3/-5
LT1763-3.3
6
4
LT1763
LT1763-5
2
0
–50
0
25
50
75 100 125
–25
–50
0
25
50
75 100 125
0
1
2
3
4
6
7
8
9
10
–25
5
TEMPERATURE (°C)
TEMPERATURE (°C)
OUTPUT VOLTAGE (V)
1763 G34
1763 G32
1763 G33
1763fa
8
LT1763 Series
U W
TYPICAL PERFORMANCE CHARACTERISTICS
Input Ripple Rejection
Input Ripple Rejection
Ripple Rejection
80
70
60
50
40
30
20
10
0
80
70
60
50
40
30
20
10
0
68
66
64
62
60
58
56
54
52
C
= 0.01µF
BYP
C
= 10µF
OUT
C
= 1000pF
BYP
C
= 100pF
BYP
I
= 500mA
L
V
= V
+
I
= 500mA
IN
OUT (NOMINAL)
L
V
= V
+
IN
OUT(NOMINAL)
1V + 0.5V RIPPLE
P-P
C
= 4.7µF
V
= V +
OUT
IN
OUT(NOMINAL)
1V + 50mV
C
RIPPLE
RMS
AT f = 120Hz
1V + 50mV
C
RIPPLE
1k
RMS
= 10µF
= 0
BYP
I
= 500mA
L
OUT
10
100
1k
10k
100k
1M
10
100
10k
100k
1M
–25
0
25
50
75
125
–50
100
FREQUENCY (Hz)
FREQUENCY (Hz)
TEMPERATURE (°C)
1763 G35
1763 G36
1763 G37
LT1763
Minimum Input Voltage
Output Noise Spectral Density
CBYP = 0
Load Regulation
5
0
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0
10
1
LT1763-1.5
LT1763-2.5
LT1763
LT1763-3
LT1763-1.8
I
= 500mA
L
LT1763-3.3
LT1763-5
–5
I
= 1mA
L
LT1763-3
–10
–15
–20
–25
LT1763
LT1763-3.3
LT1763-5
LT1763-2.5
LT1763-1.8
LT1763-1.5
0.1
0.01
V
= V
+ 1V
IN
L
OUT(NOMINAL)
C
= 10µF
OUT
∆I = 1mA TO 500mA
V
= 1.22V
I = 500mA
L
OUT
–50
0
25
50
75 100 125
–25
–25
0
25
50
75
125
–50
100
10
100
1k
FREQUENCY (Hz)
10k
100k
TEMPERATURE (°C)
TEMPERATURE (°C)
1763 G40
1763 G38
1763 G39
RMS Output Noise vs
Bypass Capacitor
RMS Output Noise vs
Load Current (10Hz to 100kHz)
Output Noise Spectral Density
160
10
1
160
140
120
100
80
C
= 10µF
C
= 10µF
C
L
= 10µF
OUT
OUT
OUT
C
= 0
I = 500mA
L
I
= 500mA
140
BYP
C
= 0.01µF
f = 10Hz TO 100kHz
BYP
C
= 1000pF
BYP
LT1763-5
LT1763
120 LT1763-5
LT1763-5
LT1763-3.3
C
= 100pF
BYP
100
80
LT1763-3
LT1763-2.5
60
60
LT1763
0.1
C
BYP
= 0.01µF
40
40
LT1763
LT1763-5
LT1763
LT1763-1.8
20
0
20
LT1763-1.5
0
0.01
0.01
10
100
1000
(pF)
10000
0.1
1
10
100
1000
10
100
1k
FREQUENCY (Hz)
10k
100k
C
BYP
LOAD CURRENT (mA)
1763 G41
1763 G42
1763 G43
1763fa
9
LT1763 Series
TYPICAL PERFORMANCE CHARACTERISTICS
U W
LT1763-5
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 100pF
LT1763-5
10Hz to 100kHz Output Noise
CBYP = 1000pF
10Hz to 100kHz Output Noise
CBYP = 0
VOUT
100µV/DIV
VOUT
100µV/DIV
VOUT
100µV/DIV
1ms/DIV
1ms/DIV
COUT = 10µF
IL = 500mA
1ms/DIV
COUT = 10µF
IL = 500mA
COUT = 10µF
1763 G46
1763 G47
I
L = 500mA
1763 G44
LT1763-5
LT1763-5
Transient Response
CBYP = 0
LT1763-5
Transient Response
CBYP = 0.01µF
10Hz to 100kHz Output Noise
CBYP = 0.01µF
V
C
C
= 6V
V
C
C
= 6V
IN
IN
IN
IN
0.4
0.2
0.10
0.05
0
= 10µF
= 10µF
= 10µF
= 10µF
OUT
OUT
0
VOUT
100µV/DIV
–0.2
–0.4
–0.05
–0.10
600
400
200
0
600
400
200
0
1ms/DIV
COUT = 10µF
IL = 500mA
1763 G45
400
TIME (µs)
40
50 60 70 80 90 100
TIME (µs)
0
200
600
800
1000
0
10 20 30
1763 G48
1763 G49
U
U
U
PIN FUNCTIONS
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).
OUT (Pin 1): Output. The output supplies power to the
load. A minimum output capacitor of 3.3µF 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.
R
P
8
1
IN
OUT
LT1763
+
SENSE (Pin 2): Output Sense. For fixed voltage versions
of the LT1763 (LT1763-1.5/LT1763-1.8/LT1763-2.5/
LT1763-3/LT1763-3.3/LT1763-5), 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
5
2
+
SHDN SENSE
GND
LOAD
V
IN
3
R
P
1763 F01
Figure 1. Kelvin Sense Connection
1763fa
10
LT1763 Series
U
U
U
PIN FUNCTIONS
Note that the voltage drop across the external PC traces
willaddtothedropoutvoltageoftheregulator. TheSENSE
pin bias current is 10µA 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.
SHDN (Pin 5): Shutdown. The SHDN pin is used to put the
LT1763 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 1µA. 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.
ADJ (Pin 2): Adjust. For the adjustable LT1763, this is the
input to the error amplifier. This pin is internally clamped
to ±7V. It has a bias current of 30nA which flows into the
pin (see curve of ADJ Pin Bias Current vs Temperature in
theTypicalPerformanceCharacteristicssection).TheADJ
pin voltage is 1.22V referenced to ground and the output
voltage range is 1.22V to 20V.
IN (Pin 8): 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
LT1763 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.
BYP (Pin 4): Bypass. The BYP pin is used to bypass the
reference of the LT1763 regulators to achieve low noise
performance from the regulator. The BYP pin is clamped
internally to ±0.6V (one VBE). A small capacitor from the
output to this pin will bypass the reference to lower the
output voltage noise. A maximum value of 0.01µF can be
usedforreducingoutputvoltagenoisetoatypical20µVRMS
over a 10Hz to 100kHz bandwidth. If not used, this pin
must be left unconnected.
GND (Pins 3, 6, 7): Ground.
U
W U U
APPLICATIONS INFORMATION
TheLT1763seriesare500mAlowdropoutregulatorswith
micropowerquiescentcurrentandshutdown.Thedevices
are capable of supplying 500mA at a dropout voltage of
300mV. Output voltage noise can be lowered to 20µVRMS
over a 10Hz to 100kHz bandwidth with the addition of a
0.01µFreferencebypasscapacitor. Additionally, therefer-
ence bypass capacitor will improve transient response of
the regulator, lowering the settling time for transient load
conditions. The low operating quiescent current (30µA)
drops to less than 1µA in shutdown. In addition to the low
quiescentcurrent, theLT1763regulatorsincorporatesev-
eral 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 LT1763-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 re-
turnedtoanegativesupply,theoutputcanbepulledbelow
groundbyasmuchas20Vandstillallowthedevicetostart
and operate.
Adjustable Operation
The adjustable version of the LT1763 has an output
voltage range of 1.22V to 20V. The output voltage is set by
theratiooftwoexternalresistorsasshowninFigure2.The
device servos the output to maintain the ADJ pin voltage
at 1.22V referenced to ground. The current in R1 is then
equalto1.22V/R1andthecurrentinR2isthecurrentinR1
1763fa
11
LT1763 Series
U
W U U
APPLICATIONS INFORMATION
plus the ADJ pin bias current. The ADJ pin bias current,
30nA 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 no greater than 250k
to minimize errors in the output voltage caused by the ADJ
pinbiascurrent.Notethatinshutdowntheoutputisturned
off and the divider current will be zero. Curves of ADJ Pin
Voltage vs Temperature and ADJ Pin Bias Current vs
Temperature appear in the Typical Performance Charac-
teristics section.
10µs, with total output voltage deviation of less than 2.5%
(see LT1763-5 Transient Response in the Typical Perfor-
mance Characteristics). However, regulator start-up time
is inversely proportional to the size of the bypass capaci-
tor, slowing to 15ms with a 0.01µF bypass capacitor and
10µF output capacitor.
Output Capacitance and Transient Response
The LT1763 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 capaci-
tors. A minimum output capacitor of 3.3µF with an ESR of
3Ω or less is recommended to prevent oscillations. The
LT1763-X is a micropower device and output transient
response will be a function of output capacitance. Larger
values of output capacitance decrease the peak deviations
and provide improved transient response for larger load
current changes. Bypass capacitors, used to decouple
individual components powered by the LT1763-X, will
increase the effective output capacitor value. With larger
capacitors used to bypass the reference (for low noise
operation), larger values of output capacitors are needed.
For 100pF of bypass capacitance, 4.7µF of output capaci-
tor is recommended. With a 1000pF bypass capacitor or
larger, a 6.8µF output capacitor is recommended.
IN
OUT
V
OUT
+
V
IN
R2
LT1763
GND
R2
R1
VOUT = 1.22V 1+
ADJ = 1.22V
ADJ = 30nA AT 25°C
OUTPUT RANGE = 1.22V TO 20V
+ I
R2
(
ADJ)(
)
ADJ
V
R1
I
1763 F02
Figure 2. Adjustable Operation
The adjustable device is tested and specified with the ADJ
pin tied to the OUT pin for an output voltage of 1.22V.
Specifications for output voltages greater than 1.22V will
beproportionalto the ratio ofthe desired outputvoltage to
1.22V: VOUT/1.22V. For example, load regulation for an
output current change of 1mA to 500mA is –2mV typical
at VOUT = 1.22V. At VOUT = 12V, load regulation is:
TheshadedregionofFigure3definestherangeoverwhich
the LT1763 regulators are stable. The minimum ESR
needed is defined by the amount of bypass capacitance
used, while the maximum ESR is 3Ω.
(12V/1.22V)(–2mV) = –19.6mV
Bypass Capacitance and Low Noise Performance
The LT1763 regulators may be used with the addition of a
bypass capacitor from VOUT to the BYP pin to lower output
voltage noise. A good quality low leakage capacitor is
recommended. This capacitor will bypass the reference of
the regulator, providing a low frequency noise pole. The
noise pole provided by this bypass capacitor will lower the
output voltage noise to as low as 20µVRMS with the
addition of a 0.01µF bypass capacitor. Using a bypass
capacitor has the added benefit of improving transient
response. With no bypass capacitor and a 10µF output
capacitor, a 10mA to 500mA load step will settle to within
1% of its final value in less than 100µs. With the addition
of a 0.01µF bypass capacitor, the output will settle to
within 1% for a 10mA to 500mA load step in less than
4.0
3.5
3.0
STABLE REGION
2.5
2.0
C
= 0
BYP
1.5
1.0
0.5
0
C
= 100pF
BYP
C
= 330pF
BYP
C
≥ 1000pF
BYP
1
3
6
9 10
7 8
2
4
5
OUTPUT CAPACITANCE (µF)
1763 F03
Figure 3. Stability
1763fa
12
LT1763 Series
U
W U U
APPLICATIONS INFORMATION
20
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 Z5U, Y5V, X5R and X7R. The Z5U and
Y5V dielectrics are good for providing high capacitances
in a small package, but exhibit strong voltage and tem-
perature coefficients as shown in Figures 4 and 5. When
used with a 5V regulator, a 10µF Y5V capacitor can exhibit
an effective value as low as 1µF to 2µF 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.
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
0
X5R
–20
–40
–60
Y5V
–80
–100
0
8
12 14
2
4
6
10
16
DC BIAS VOLTAGE (V)
1763 F04
Figure 4. Ceramic Capacitor DC Bias Characteristics
40
20
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 micro-
phone works. For a ceramic capacitor the stress can be
induced by vibrations in the system or thermal transients.
The resulting voltages produced can cause appreciable
amounts of noise, especially when a ceramic capacitor is
used for noise bypassing. A ceramic capacitor produced
Figure 6’s trace in response to light tapping from a pencil.
Similar vibration induced behavior can masquerade as
increased output voltage noise.
X5R
0
–20
–40
Y5V
–60
–80
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
–100
50
TEMPERATURE (°C)
75
100 125
–50 –25
0
25
1763 F05
Figure 5. Ceramic Capacitor Temperature Characteristics
Thermal Considerations
LT1763-5
COUT = 10µF
CBYP = 0.01µf
ILOAD = 100mA
The power handling capability of the device will be limited
by the maximum rated junction temperature (125°C). The
power dissipated by the device will be made up of two
components:
VOUT
500µV/DIV
1. Output current multiplied by the input/output voltage
differential: (IOUT)(VIN – VOUT), and
2. GND pin current multiplied by the input voltage:
(IGND)(VIN).
100ms/DIV
1763 F06
Figure 6. Noise Resulting from Tapping on a Ceramic Capacitor
The GND pin current can be found by examining the GND
Pin Current curves in the Typical Performance Character-
istics.Powerdissipationwillbeequaltothesumofthetwo
components listed above.
1763fa
13
LT1763 Series
U
W U U
APPLICATIONS INFORMATION
The LT1763 series regulators have internal thermal limit-
ing designed to protect the device during overload condi-
tions. For continuous normal conditions, the maximum
junction temperature rating of 125°C must not be
exceeded. It is important to give careful consideration to
allsourcesofthermalresistancefromjunctiontoambient.
Additional heat sources mounted nearby must also be
considered.
P = 250mA(6V – 3.3V) + 5mA(6V) = 0.71W
The thermal resistance will be in the range of 60°C/W to
86°C/W depending on the copper area. So the junction
temperature rise above ambient will be approximately
equal to:
0.71W(75°C/W) = 53.3°C
The maximum junction temperature will then be equal to
the maximum junction temperature rise above ambient
plus the maximum ambient temperature or:
For surface mount devices, heat sinking is accomplished
by using the heat spreading capabilities of the PC board
and its copper traces. Copper board stiffeners and plated
through-holes can also be used to spread the heat gener-
ated by power devices.
TJMAX = 50°C + 53.3°C = 103.3°C
Protection Features
The following table lists thermal resistance for several
different board sizes and copper areas. All measurements
were taken in still air on 3/32" FR-4 board with one ounce
copper.
The LT1763 regulators incorporate several protection
featureswhichmakethemidealforuseinbattery-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.
Table 1. Measured Thermal Resistance
COPPER AREA
THERMAL RESISTANCE
TOPSIDE* BACKSIDE
BOARD AREA (JUNCTION-TO-AMBIENT)
Current limit protection and thermal overload protection
areintendedtoprotectthedeviceagainstcurrentoverload
conditions at the output of the device. For normal opera-
tion, the junction temperature should not exceed 125°C.
2500mm2
1000mm2
225mm2
100mm2
50mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
60°C/W
60°C/W
68°C/W
74°C/W
86°C/W
The input of the device will withstand reverse voltages of
20V.Currentflowintothedevicewillbelimitedtolessthan
1mA (typically less than 100µA) 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.
*Device is mounted on topside.
Calculating Junction Temperature
Example: Given an output voltage of 3.3V, an input voltage
range of 4V to 6V, an output current range of 0mA to
250mA and a maximum ambient temperature of 50°C,
what will the maximum junction temperature be?
The output of the LT1763-X can be pulled below ground
withoutdamagingthedevice.Iftheinputisleftopencircuit
or grounded, the output can be pulled below ground by
20V. For fixed voltage versions, the output will act like a
large resistor, typically 500kΩ or higher, limiting current
flow to less than 100µA. 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 power dissipated by the device will be equal to:
IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)
where,
)
IOUT(MAX) = 250mA
VIN(MAX) = 6V
IGND at (IOUT = 250mA, VIN = 6V) = 5mA
So,
1763fa
14
LT1763 Series
U
W U U
APPLICATIONS INFORMATION
The ADJ pin of the adjustable device can be pulled above
or below ground by as much as 7V without damaging the
device. Iftheinputisleftopencircuitorgrounded, theADJ
pin will act like an open circuit when pulled below ground
and like a large resistor (typically 100k) in series with a
diode when pulled above ground.
When the IN pin of the LT1763-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.
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
fromthe1.22Vreferencewhentheoutputisforcedto20V.
The top resistor of the resistor divider must be chosen to
limitthecurrentintotheADJpintolessthan5mAwhenthe
ADJ pin is at 7V. The 13V difference between output and
ADJpindividedbythe5mAmaximumcurrentintotheADJ
pin yields a minimum top resistor value of 2.6k.
100
T = 25°C
IN
J
V
LT1763-1.5
= 0V
90
80
70
60
50
40
30
20
10
0
CURRENT FLOWS
INTO OUTPUT PIN
V
OUT
= V
ADJ
(LT1763)
LT1763
LT1763-1.8
LT1763-2.5
LT1763-3
LT1763-5
LT1763-3.3
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, pulledtosomeintermediatevoltageorisleftopen
circuit. Current flow back into the output will follow the
curve shown in Figure 7.
4
0
1
2
3
5
6
7
8
9
10
OUTPUT VOLTAGE (V)
1763 F07
Figure 7. Reverse Output Current
U
TYPICAL APPLICATION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
.160 ±.005
.050 BSC
7
5
8
6
.053 – .069
(1.346 – 1.752)
.004 – .010
(0.101 – 0.254)
.245
MIN
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
.010 – .020
(0.254 – 0.508)
.030 ±.005
TYP
× 45°
1
2
3
4
RECOMMENDED SOLDER PAD LAYOUT
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
NOTE:
INCHES
(MILLIMETERS)
1. DIMENSIONS IN
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
.016 – .050
2. DRAWING NOT TO SCALE
(0.406 – 1.270)
SO8 0303
1763fa
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 represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LT1763 Series
U
TYPICAL APPLICATION
Paralleling of Regulators for Higher Output Current
R1
0.1Ω
3.3V
1A
IN
OUT
SENSE
LT1763-3.3
+
+
C1
10µF
C2
10µF
V
IN
> 3.8V
C4
0.01µF
SHDN
BYP
GND
R2
0.1Ω
IN
OUT
C5
0.01µF
R6
LT1763
2k
BYP
ADJ
SHDN
SHDN
GND
R3
2.2k
R4
2.2k
R7
1.21k
8
3
2
R5
10k
+
1
1/2 LT1490
C3
–
4
0.01µF
1763 TA03
RELATED PARTS
PART NUMBER
LT1120
DESCRIPTION
COMMENTS
Includes 2.5V Reference and Comparator
125mA Low Dropout Regulator with 20µA I
Q
LT1121
150mA Micropower Low Dropout Regulator
700mA Micropower Low Dropout Regulator
30µA I , SOT-223 Package
Q
LT1129
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LT1175
500mA Negative Low Dropout Micropower Regulator
300mA Low Dropout Micropower Regulator with Shutdown
3A Low Dropout Regulator with 50µA I
45µA I , 0.26V Dropout Voltage, SOT-223 Package
Q
LT1521
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Q
LT1529
500mV Dropout Voltage
Q
LT1613
1.4MHz Single-Cell Micropower DC/DC Converter
SOT-23 Package, Internally Compensated
LT1761 Series
LT1762 Series
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Noise, ThinSOT
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RMS
RMS
150mA, Low Noise, LDO Micropower Regulators
3A, Fast Transient Response Low Dropout Regulator
300mA, Fast Transient Response Low Dropout Regulator
1.5A, Fast Transient Response Low Dropout Regulator
50mA, 80V Low Noise, LDO Micropower Regulator
25µA Quiescent Current, 20µV
340mV Dropout Voltage, DD, TO220
270mV Dropout Voltage, 20µV
340mV Dropout Voltage, 40µV
, MS8
RML
RML
LT1963A
LT3010
, DD, TO220, S8, SOT-223
300mV Dropout Voltage, MS8E
1763fa
LT/TP 1003 1K • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
LINEAR TECHNOLOGY CORPORATION 1999
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