LT1962EMS8-1.8 [Linear]
300mA, Low Noise, Micropower LDO Regulators; 300mA，低噪声，微功率LDO稳压器
| 型号： | LT1962EMS8-1.8 |
| 厂家： | 
Linear |
| 描述： | 300mA, Low Noise, Micropower LDO Regulators |
| 文件： | 总16页 (文件大小：292K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1962 Series
300mA, Low Noise,
Micropower
LDO Regulators
U
FEATURES
DESCRIPTIO
The LT®1962 series are micropower, low noise, low
dropout regulators. The devices are capable of supplying
300mAofoutputcurrentwithadropoutvoltageof270mV.
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: 300mA
■
Low Quiescent Current: 30µA
■
Wide Input Voltage Range: 1.8V to 20V
■
Low Dropout Voltage: 270mV
■
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 LT1962 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 LT1962 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 MSOP Package
Internal protection circuitry includes reverse battery pro-
tection, current limiting, thermal limiting and reverse cur-
rent protection. The parts come in fixed output voltages of
1.5V, 1.8V, 2.5V, 3V, 3.3V and 5V, and as an adjustable
device with a 1.22V reference voltage. The LT1962 regu-
lators are available in the 8-lead MSOP 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
3.3V Low Noise Regulator
350
300
250
200
150
100
50
3.3V AT 300mA
20µV NOISE
IN
OUT
V
IN
RMS
+
3.7V TO
20V
1µF
SENSE
10µF
LT1962-3.3
0.01µF
SHDN
GND
BYP
1962 TA01
0
0
50
100
150
200
250
300
LOAD CURRENT (mA)
1962 TA02
1
LT1962 Series
W W U W
U W
U
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
(Note 1)
ORDER PART
NUMBER
IN Pin Voltage........................................................ ±20V
OUT Pin Voltage .................................................... ±20V
Input to Output Differential Voltage (Note 2) ......... ±20V
SENSE Pin Voltage ............................................... ±20V
ADJ Pin Voltage ...................................................... ±7V
BYP Pin Voltage.................................................... ±0.6V
SHDN Pin Voltage................................................. ±20V
Output Short-Circuit Duration......................... Indefinite
Operating Junction Temperature Range
TOP VIEW
LT1962EMS8
LT1962EMS8-1.5
LT1962EMS8-1.8
LT1962EMS8-2.5
LT1962EMS8-3
LT1962EMS8-3.3
LT1962EMS8-5
OUT
SENSE/ADJ*
BYP
1
2
3
4
8 IN
7 NC
6 NC
5 SHDN
GND
MS8 PACKAGE
8-LEAD PLASTIC MSOP
*PIN 2: SENSE FOR LT1962-1.5/LT1962-1.8/
LT1962-2.5/LT1962-3/LT1962-3.3/LT1962-5.
ADJ FOR LT1962
TJMAX = 150°C, θJA = 125°C/ W
MS8 PART MARKING
(Note 3) ............................................ –40°C to 125°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
SEE THE APPLICATIONS
INFORMATION SECTION
FOR ADDITIONAL
INFORMATION ON
THERMAL RESISTANCE
LTML LTPQ
LTSZ LTPS
LTTA LTPR
LTPT
Consult factory 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 3)
PARAMETER
CONDITIONS
(LT1962)
MIN
TYP
MAX
UNITS
Minimum Operating Voltage
I
= 300mA (Notes 4, 12)
●
●
●
●
●
●
●
●
1.8
2.3
V
LOAD
Regulated Output Voltage
(Notes 4, 5)
LT1962-1.5
V
= 2V, I
= 1mA
1.485
1.462
1.500
1.500
1.515
1.538
V
V
IN
LOAD
2.5V < V < 20V, 1mA < I
< 300mA
< 300mA
< 300mA
IN
LOAD
LOAD
LOAD
LT1962-1.8
LT1962-2.5
LT1962-3
LT1962-3.3
LT1962-5
LT1962
V
= 2.3V, I
= 1mA
1.782
1.755
1.800
1.800
1.818
1.845
V
V
IN
LOAD
2.8V < V < 20V, 1mA < I
IN
V
= 3V, I
= 1mA
2.475
2.435
2.500
2.500
2.525
2.565
V
V
IN
LOAD
3.5V < V < 20V, 1mA < I
IN
V
= 3.5V, I
IN
= 1mA
2.970
2.925
3.000
3.000
3.030
3.075
V
V
IN
LOAD
4V < V < 20V, 1mA < I
< 300mA
LOAD
V
= 3.8V, I
= 1mA
3.267
3.220
3.300
3.300
3.333
3.380
V
V
IN
LOAD
4.3V < V < 20V, 1mA < I
< 300mA
IN
LOAD
V
= 5.5V, I
IN
= 1mA
4.950
4.875
5.000
5.000
5.050
5.125
V
V
IN
LOAD
6V < V < 20V, 1mA < I
< 300mA
LOAD
ADJ Pin Voltage
(Notes 4, 5)
V
= 2V, I
= 1mA
1.208
1.190
1.220
1.220
1.232
1.250
V
V
IN
LOAD
2.3V < V < 20V, 1mA < I
< 300mA
IN
LOAD
Line Regulation
Load Regulation
2
LT1962-1.5
LT1962-1.8
LT1962-2.5
LT1962-3
LT1962-3.3
LT1962-5
∆V = 2V to 20V, I
= 1mA
= 1mA
LOAD
●
●
●
●
●
●
●
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
IN
∆V = 3V to 20V, I
= 1mA
IN
LOAD
∆V = 3.5V to 20V, I
= 1mA
= 1mA
= 1mA
IN
LOAD
LOAD
LOAD
∆V = 3.8V to 20V, I
IN
∆V = 5.5V to 20V, I
IN
LT1962 (Note 4) ∆V = 2V to 20V, I
= 1mA
IN
LOAD
LT1962-1.5
LT1962-1.8
V
V
= 2.5V, ∆I
= 2.5V, ∆I
= 1mA to 300mA
= 1mA to 300mA
3
8
15
mV
mV
IN
IN
LOAD
LOAD
●
●
V
V
= 2.8V, ∆I
= 2.8V, ∆I
= 1mA to 300mA
= 1mA to 300mA
4
9
18
mV
mV
IN
IN
LOAD
LOAD
LT1962 Series
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 3)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Load Regulation
LT1962-2.5
V
V
= 3.5V, ∆I
= 3.5V, ∆I
= 1mA to 300mA
= 1mA to 300mA
5
12
25
mV
mV
IN
IN
LOAD
LOAD
●
●
●
●
●
●
●
●
●
LT1962-3
V
V
= 4V, ∆I
= 4V, ∆I
= 1mA to 300mA
= 1mA to 300mA
7
15
30
mV
mV
IN
IN
LOAD
LOAD
LT1962-3.3
LT1962-5
V
V
= 4.3V, ∆I
= 4.3V, ∆I
= 1mA to 300mA
= 1mA to 300mA
7
17
33
mV
mV
IN
IN
LOAD
LOAD
V
V
= 6V, ∆I
= 6V, ∆I
= 1mA to 300mA
= 1mA to 300mA
12
25
50
mV
mV
IN
IN
LOAD
LOAD
LT1962 (Note 4)
V
V
= 2.3V, ∆I
= 2.3V, ∆I
= 1mA to 300mA
= 1mA to 300mA
2
6
12
mV
mV
IN
IN
LOAD
LOAD
Dropout Voltage
I
I
= 10mA
= 10mA
0.10
0.15
0.18
0.27
0.15
0.21
V
V
LOAD
LOAD
V
= V
IN
OUT(NOMINAL)
(Notes 6, 7, 12)
I
I
= 50mA
= 50mA
0.20
0.28
V
V
LOAD
LOAD
I
I
= 100mA
= 100mA
0.24
0.33
V
V
LOAD
LOAD
I
I
= 300mA
= 300mA
0.33
0.43
V
V
LOAD
LOAD
GND Pin Current
I
I
I
I
I
= 0mA
= 1mA
= 50mA
= 100mA
= 300mA
●
●
●
●
●
30
65
1.1
2
75
120
1.6
3
µA
µA
mA
mA
mA
LOAD
LOAD
LOAD
LOAD
LOAD
V
= V
IN
OUT(NOMINAL)
(Notes 6, 8)
8
12
Output Voltage Noise
ADJ Pin Bias Current
Shutdown Threshold
C
= 10µF, C
= 0.01µF, I
= 300mA, BW = 10Hz to 100kHz
20
30
µV
RMS
OUT
BYP
LOAD
(Notes 4, 9)
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 10)
V
V
= 0V
= 20V
0.01
1
0.5
5
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
55
dB
IN
OUT
RIPPLE
I
= 300mA
LOAD
Current Limit
V
V
= 7V, V
= V
= 0V
700
mA
mA
IN
IN
OUT
OUT(NOMINAL)
+ 1V, ∆V
= –0.1V
●
●
320
OUT
Input Reverse Leakage Current
V
= –20V, V
= 0V
OUT
1
mA
IN
Reverse Output Current
(Note 11)
LT1962-1.5
LT1962-1.8
LT1962-2.5
LT1962-3
LT1962-3.3
LT1962-5
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
= 3.3V, V < 3.3V
IN
= 5V, V < 5V
IN
LT1962 (Note 4)
= 1.22V, V < 1.22V
IN
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 3: The LT1962 regulators are tested and specified under pulse load
conditions such that T ≈ T . The LT1962 is 100% tested at T = 25°C.
J
A
A
Performance at –40°C and 125°C is assured by design, characterization
and correlation with statistical process controls.
Note 4: The LT1962 (adjustable version) is tested and specified for these
conditions with the ADJ pin connected to the OUT pin.
Note 2: Absolute maximum input to output differential voltage cannot be
achieved with all combinations of rated IN pin and OUT pin voltages. With
the IN pin at 20V, the OUT pin may not be pulled below 0V. The total
measured voltage from in to out can not exceed ±20V.
3
LT1962 Series
ELECTRICAL CHARACTERISTICS
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 9: ADJ pin bias current flows into the ADJ pin.
Note 10: SHDN pin current flows into the SHDN pin. This current is
Note 5: 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.
included in the specification for GND pin current.
Note 6: To satisfy requirements for minimum input voltage, the LT1962
(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.
Note 7: Dropout voltage is the minimum input to output voltage differential
needed to maintain regulation at a specified output current. In dropout, the
Note 11: 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 12: For the LT1962, LT1962-1.5 and LT1962-1.8 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. For other fixed voltage versions of
the LT1962, the minimum input voltage is limited by the dropout voltage.
output voltage will be equal to: V – V
.
IN
DROPOUT
Note 8: 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
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Typical Dropout Voltage
Guaranteed Dropout Voltage
Dropout Voltage
400
350
300
250
200
150
100
50
500
450
400
350
300
250
200
150
100
50
400
350
300
250
= TEST POINTS
T
≤ 125°C
J
I
= 300mA
T
= 125°C
= 25°C
L
J
T
≤ 25°C
J
I
= 100mA
L
200
150
T
J
I
= 50mA
L
I
= 10mA
L
100
50
0
I
L
= 1mA
0
0
50
100
200
0
50
150
200
250
300
–25
0
50
75 100 125
0
250
300
–50
25
150
100
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
TEMPERATURE (°C)
1962 G01
1962 G02
1962 G03
LT1962-1.8 Output Voltage
Quiescent Current
LT1962-1.5 Output Voltage
50
45
40
35
30
25
20
15
10
5
1.532
1.524
1.516
1.508
1.500
1.492
1.484
1.476
1.468
1.836
1.827
1.818
1.809
1.800
1.791
1.782
1.773
1.764
I
L
= 1mA
I = 1mA
L
V
V
= 6V
IN
SHDN
L
= V
L
IN
R
=
∞
, I = 0 (LT1962-1.5/-1.8
/2.5/-3/-3.3/-5)
= 250k, I = 5µA (LT1962)
R
L
L
0
–50
0
25
50
75 100 125
50
75
50
75
–25
–50 –25
0
25
100 125
–50 –25
0
25
100 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1962 G04
1962 G05
1962 G06
4
LT1962 Series
U W
TYPICAL PERFOR A CE CHARACTERISTICS
LT1962-2.5 Output Voltage
LT1962-3.3 Output Voltage
LT1962-3 Output Voltage
2.54
2.53
2.52
2.51
2.50
2.49
2.48
2.47
2.46
3.060
3.045
3.030
3.015
3.000
2.985
2.970
2.955
2.940
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
50
75 100 125
–50 –25
0
25
50
75 100 125
–25
–50
0
25
50
75 100 125
–50
25
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1962 G07
1962 G08
1962 G09
LT1962-5 Output Voltage
LT1962 ADJ Pin Voltage
LT1962-1.5 Quiescent Current
5.100
5.075
5.050
5.025
5.000
4.975
4.950
4.925
4.900
1.240
1.235
1.230
1.225
1.220
1.215
1.210
1.205
1.200
800
700
600
500
400
300
200
100
0
I
= 1mA
I = 1mA
L
T
= 25°C
L
J
L
R
=
∞
V
= 0V
8
SHDN
7
V
= V
5
SHDN
4
IN
–25
0
50
75 100 125
–25
0
50
75 100 125
–50
25
–50
25
0
1
2
3
6
9
10
TEMPERATURE (°C)
TEMPERATURE (°C)
INPUT VOLTAGE (V)
1962 G10
1962 G11
1962 G12
LT1962-1.8 Quiescent Current
LT1962-2.5 Quiescent Current
LT1962-3 Quiescent Current
800
700
600
500
400
300
200
100
0
800
700
600
500
400
300
200
100
0
800
700
600
500
400
300
200
100
0
T
= 25°C
T
J
L
= 25°C
T
= 25°C
J
L
J
R
=
∞
R
=
∞
R
= ∞
L
V
= 0V
8
V
= 0V
8
V
= 0V
8
SHDN
7
SHDN
7
SHDN
7
V
= V
5
V
= V
5
V
= V
5
SHDN
4
IN
SHDN
4
IN
SHDN
4
IN
0
1
2
3
6
9
10
0
1
2
3
6
9
10
0
1
2
3
6
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1962 G14
1962 G15
1962 G13
5
LT1962 Series
TYPICAL PERFOR A CE CHARACTERISTICS
U W
LT1962-3.3 Quiescent Current
LT1962-5 Quiescent Current
LT1962 Quiescent Current
800
700
600
500
400
300
200
100
0
800
700
600
500
400
300
200
100
0
40
35
30
25
20
15
10
5
T
= 25°C
=
T
= 25°C
T = 25°C
J
R = 250k
L
J
L
J
L
R
∞
R
=
∞
V
= V
IN
SHDN
V
= 0V
9
V
= 0V
8
SHDN
SHDN
7
V
= V
V
= V
SHDN
IN
SHDN
6
IN
V
= 0V
SHDN
8
0
0
1
2
3
4
5
6
9
10
0
1
2
3
4
5
7
8
10
0
2
4
6
10 12 14 16 18 20
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1962 G16
1962 G17
1962 G18
LT1962-1.5 GND Pin Current
LT1962-1.8 GND Pin Current
LT1962-2.5 GND Pin Current
1500
1250
1500
1250
1500
1250
T = 25°C
T = 25°C
T = 25°C
J
J
IN
*FOR V
J
IN
*FOR V
V
= V
V
= V
V
= V
SHDN
OUT
SHDN
= 1.8V
IN
*FOR V
SHDN
OUT
= 1.5V
= 2.5V
OUT
R
L
= 30Ω
L
R
L
= 36Ω
L
R
L
= 50Ω
I
= 50mA*
L
1000
750
1000
750
1000
750
I
= 50mA*
I
= 50mA*
R
L
= 250Ω
L
500
250
0
500
250
0
500
250
0
I
= 10mA*
R
L
= 150Ω
R
L
= 1.5k
R
L
= 180Ω
R
L
= 1.8k
R = 2.5k
L
I = 1mA*
L
L
L
L
L
I
= 10mA*
I
= 1mA*
I
= 10mA*
I
= 1mA*
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1962 G19
1962 G20
1962 G21
LT1962-3 GND Pin Current
LT1962-3.3 GND Pin Current
LT1962-5 GND Pin Current
1500
1250
1500
1250
1500
1250
T = 25°C
T = 25°C
T = 25°C
J
J
IN
*FOR V
J
IN
*FOR V
V
= V
V
= V
V
= V
SHDN
= 3V
SHDN
IN
SHDN
= 5V
= 3.3V
*FOR V
OUT
OUT
OUT
R
L
= 66Ω
L
R
L
= 60Ω
L
R
L
= 100Ω
1000
750
1000
750
1000
750
L
I
= 50mA*
I
= 50mA*
I
= 50mA*
R
L
= 330Ω
= 10mA*
R = 500Ω
L
I = 10mA*
L
L
I
R
L
= 300Ω
= 10mA*
L
500
250
0
500
250
0
500
250
0
I
R
I
= 3k
R
I
= 3.3k
R = 5k
L
I = 1mA*
L
L
L
L
L
= 1mA*
= 1mA*
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1962 G22
1962 G23
1962 G24
6
LT1962 Series
U W
TYPICAL PERFOR A CE CHARACTERISTICS
LT1962 GND Pin Current
LT1962-1.5 GND Pin Current
LT1962-1.8 GND Pin Current
1500
1250
8
7
6
5
4
3
2
1
0
8
7
6
5
4
3
2
1
0
T = 25°C
T = 25°C
T = 25°C
J
J
IN
*FOR V
J
IN
V
= V
V
= V
V
= V
SHDN
= 1.22V
SHDN
IN SHDN
*FOR V = 1.5V
*FOR V
= 1.8V
OUT
OUT
OUT
R
= 6Ω
L
R
L
= 24.4Ω
R = 5Ω
L
I = 300mA*
L
L
I
= 300mA*
L
I
= 50mA*
1000
750
R
= 9Ω
L
R
L
= 7.5Ω
I
= 200mA*
L
L
I
= 200mA*
R
L
= 15Ω
500
250
0
L
R
L
= 18Ω
L
R
L
= 1.22k
R
L
= 122Ω
I
= 100mA*
L
L
I
= 100mA*
I
= 1mA*
I
= 10mA*
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1962 G25
1962 G26
1962 G27
LT1962-2.5 GND Pin Current
LT1962-3 GND Pin Current
LT1962-3.3 GND Pin Current
8
7
6
5
4
3
2
1
0
8
7
6
5
4
3
2
1
0
8
7
6
5
4
3
2
1
0
T
= 25°C
T = 25°C
T = 25°C
J
J
J
V
V
= V
= V
V
= V
IN
SHDN
IN
*FOR V
SHDN
= 3V
IN SHDN
*FOR V
= 2.5V
*FOR V
= 3.3V
OUT
OUT
OUT
R
L
= 10Ω
L
R
L
= 11Ω
I
= 300mA*
R
L
= 8.33Ω
L
L
I
= 300mA*
I
= 300mA*
R
L
= 16.5Ω
R
L
= 15Ω
= 200mA*
R
L
= 12.5Ω
L
L
L
I
= 200mA*
I
I
= 200mA*
R
L
= 25Ω
= 100mA*
L
R = 33Ω
L
I = 100mA*
L
R
L
= 30Ω
= 100mA*
L
I
I
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
1962 G28
1962 G29
1962 G30
LT1962-5 GND Pin Current
LT1962 GND Pin Current
GND Pin Current vs ILOAD
8
7
6
5
4
3
2
1
0
8
7
6
5
4
3
2
1
0
8
7
6
5
T
= 25°C
T = 25°C
J
V
IN
= V
+ 1V
J
OUT(NOMINAL)
V
= V
V = V
IN
SHDN
IN SHDN
*FOR V
= 5V
*FOR V = 1.22V
OUT
OUT
R
L
= 16.7Ω
L
R
L
= 4.07Ω
L
I
= 300mA*
I
= 300mA*
R
L
= 25Ω
L
4
3
I
= 200mA*
R
L
= 6.1Ω
L
I
= 200mA*
R
L
= 50Ω
L
I
= 100mA*
2
1
0
R
L
= 12.2Ω
L
I
= 100mA*
50
100
200
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
0
250
300
150
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
1962 G31
1962 G32
1962 G33
7
LT1962 Series
TYPICAL PERFOR A CE 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
I
= 1mA
L
1.0
I
= 300mA
L
0.8
0.6
0.4
0.2
I
= 1mA
L
0
–50
0
25
50
75 100 125
–25
50
TEMPERATURE (°C)
125
10
–50
0
25
75 100
0
3
5
6
7
8
9
–25
1
2
4
TEMPERATURE (°C)
SHDN PIN VOLTAGE (V)
1962 G34
1962 G35
1962 G36
SHDN Pin Input Current
ADJ Pin Bias Current
Current Limit
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1.6
35
30
V
OUT
= 0V
V
= 20V
SHDN
1.4
1.2
25
20
15
10
5
1.0
0.8
0.6
0.4
0.2
0
0
–25
0
50
75 100 125
50
TEMPERATURE (°C)
100 125
0
2
3
4
5
7
–50
25
–50 –25
0
25
75
6
1
INPUT VOLTAGE (V)
TEMPERATURE (°C)
1962 G37
1962 G38
1962 G39
Current Limit
Reverse Output Current
Reverse Output Current
100
90
80
70
60
50
1.2
1.0
0.8
0.6
30
25
20
15
T = 25°C
IN
V
V
= 7V
V
V
V
V
V
V
V
V
= 0V
LT1962
J
V
IN
OUT
IN
= 0V
= 0V
= 1.22V (LT1962)
= 1.5V (LT1962-1.5)
= 1.8V (LT1962-1.8)
= 2.5V (LT1962-2.5)
= 3V (LT1962-3)
OUT
OUT
OUT
OUT
OUT
OUT
OUT
CURRENT FLOWS
INTO OUTPUT PIN
V
OUT
= V
ADJ
(LT1962)
LT1962-1.5
= 3.3V (LT1962-3.3)
= 5V (LT1962-5)
LT1962-1.8
LT1962-2.5
LT1962-1.5/-1.8/-2.5/-3/-3.3/-5
40
30
LT1962-3
LT1962-3.3
0.4
0.2
0
10
5
20
10
0
LT1962-5
LT1962
0
50
TEMPERATURE (°C)
100 125
2
3
6
–50 –25
0
25
75
0
1
4
5
7
8
9
10
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
OUTPUT VOLTAGE (V)
1962 G40
1962 F07
1962 G42
8
LT1962 Series
U W
TYPICAL PERFOR A CE 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
I
= 300mA
C
= 0.01µF
L
BYP
V
= V
+ 1V
IN
OUT(NOMINAL)
66
64
+ 50mV
C
RIPPLE
RMS
= 0
C
= 1000pF
BYP
BYP
C
= 10µF
62
60
58
56
54
OUT
C
= 100pF
BYP
C
= 3.3µF
OUT
I
= 300mA
= V
L
IN
V
+ 1V
OUT(NOMINAL)
I
= 300mA
L
V
+ 50mV
C
RIPPLE
= V
+ 1V
RMS
IN
OUT(NOMINAL)
= 10µF
+ 0.5V RIPPLE AT f = 120Hz
OUT
P-P
52
10
100
1k
10k
100k
1M
10
100
1k
10k
100k
1M
–25
0
50
75 100 125
–50
25
FREQUENCY (Hz)
FREQUENCY (Hz)
TEMPERATURE (°C)
1962 G43
1962 G44
1962 G45
LT1962 Minimum Input Voltage
Load Regulation
Output Noise Spectral Density
10
1
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0
5
0
I
C
C
= 300mA
V
OUT
= 1.22V
L
= 10µF
OUT
BYP
LT1962-1.8
LT1962
= 0
LT1962-1.5
LT1962-3
LT1962-3.3
I
L
= 300mA
LT1962-5
–5
–10
I
L
= 1mA
LT1962-3.3
LT1962-3
LT1962-2.5
LT1962
LT1962-2.5
LT1962-5
0.1
0.01
–15
–20
–25
LT1962-1.8
LT1962-1.5
V
= V
+ 1V
IN
L
OUT(NOMINAL)
∆I = 1mA TO 300mA
–50
0
25
50
75 100 125
–50 –25
0
25
50
75
100 125
–25
10
100
1k
10k
100k
TEMPERATURE (°C)
FREQUENCY (Hz)
TEMPERATURE (°C)
1962 G48
1962 G46
1962 G47
RMS Output Noise
vs Bypass Capacitor
RMS Output Noise
vs Load Current (10Hz to 100kHz)
Output Noise Spectral Density
10
1
160
140
120
100
80
160
140
120
100
80
I
= 300mA
OUT
C
OUT
= 10µF
I
= 300mA
OUT
L
L
C
= 10µF
C
BYP
C
BYP
= 0µF
C
= 10µF
= 0.01µF
f = 10Hz to 100kHz
LT1962-5
LT1962-5
LT1962
C
= 1000pF
BYP
LT1962-5
LT1962-3
LT1962-3.3
LT1962-2.5
LT1962-1.8
LT1962-1.5
C
= 100pF
BYP
60
60
C
= 0.01µF
LT1962
BYP
0.1
0.01
40
40
LT1962
LT1962-5
20
20
LT1962
100
0
0
0.01
0.1
1
10
1000
10
100
1k
10k
10
100
1k
FREQUENCY (Hz)
10k
100k
LOAD CURRENT (mA)
C
BYP
(pF)
1962 G51
1962 G49
1962 G50
9
LT1962 Series
TYPICAL PERFOR A CE CHARACTERISTICS
U W
LT1962-5 10Hz to 100kHz
Output Noise (CBYP = 100pF)
LT1962-5 10Hz to 100kHz
Output Noise (CBYP = 1000pF)
LT1962-5 10Hz to 100kHz
Output Noise (CBYP = 0)
VOUT
100µV/DIV
VOUT
100µV/DIV
VOUT
100µV/DIV
COUT = 10µF
IL = 300mA
1ms/DIV
1962 G53
COUT = 10µF
IL = 300mA
1ms/DIV
1962 G54
COUT = 10µF
IL = 300mA
1ms/DIV
1962 G52
LT1962-5 Transient Response
LT1962-5 Transient Response
LT1962-5 10Hz to 100kHz
Output Noise (CBYP = 0.01µF)
V
C
C
C
= 6V
V
C
C
C
= 6V
IN
IN
IN
IN
0.4
0.10
= 10µF
= 10µF
= 10µF
= 10µF
OUT
BYP
OUT
BYP
0.2
0
0.05
0
= 0
= 0.01µF
–0.2
–0.4
–0.05
–0.10
VOUT
100µV/DIV
300
200
100
0
300
200
100
0
0
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
50 100 150 200 250 300 350 400 450 500
C
OUT = 10µF
1ms/DIV
1962 G55
IL = 300mA
TIME (ms)
TIME (µs)
1962 G56
1962 G57
U
U
U
PI FU CTIO S
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.
arecausedbytheresistance(RP)ofPCtracesbetweenthe
regulator and the load. These may be eliminated by con-
necting 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 10µA at the nominal rated output voltage. The
SENSEpincanbepulledbelowground(asinadualsupply
system where the regulator load is returned to a negative
supply) and still allow the device to start and operate.
SENSE (Pin 2): Sense. For fixed voltage versions of the
LT1962(LT1962-1.5/LT1962-1.8/LT1962-2.5/LT1962-3/
LT1962-3.3/LT1962-5), 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 voltage drops
ADJ (Pin 2): Adjust. For the adjustable LT1962, 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
10
LT1962 Series
U
U
U
PI FU CTIO S
R
P
8
1
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 not function if
the SHDN pin is not connected.
IN
OUT
LT1962
5
2
+
+
SHDN SENSE
LOAD
V
IN
GND
4
R
P
1962 F01
NC (Pins 6, 7): No Connect. These pins are not internally
connected. For improved power handling capabilities,
these pins can be connected to the PC board.
Figure 1. Kelvin Sense Connection
pin.TheADJpinvoltageis1.22Vreferencedtogroundand
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
LT1962 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 3): Bypass. The BYP pin is used to bypass the
reference of the LT1962 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 used for
reducing output voltage noise to a typical 20µVRMS over a
10Hz to 100kHz bandwidth. If not used, this pin must be
left unconnected.
GND (Pin 4): Ground.
SHDN (Pin 5): Shutdown. The SHDN pin is used to put the
LT1962 regulators into a low power shutdown state. The
output will be off when the SHDN pin is pulled low. The
W U U
U
APPLICATIO S I FOR ATIO
TheLT1962seriesare300mAlowdropoutregulatorswith
micropowerquiescentcurrentandshutdown.Thedevices
are capable of supplying 300mA 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, theLT1962regulatorsincorporatesev-
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 LT1962-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 LT1962 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
11
LT1962 Series
APPLICATIO S I FOR ATIO
W U U
U
(see LT1962-5 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.
IN
OUT
V
OUT
+
V
LT1962
R2
IN
ADJ
R1
GND
1962 F02
Output Capacitance and Transient Response
R2
R1
VOUT = 1.22V 1+
ADJ = 1.22V
ADJ = 30nA AT 25°C
OUTPUT RANGE = 1.22V TO 20V
+ I
R2
(
ADJ)(
)
The LT1962 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
LT1962-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 LT1962, will in-
crease the effective output capacitor value. With larger
capacitors used to bypass the reference (for low noise
operation),largervaluesofoutputcapacitanceareneeded.
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.
V
I
Figure 2. Adjustable Operation
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.
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
be proportional to the ratio of the desired output voltage to
1.22V: VOUT/1.22V. For example, load regulation for an
output current change of 1mA to 300mA is –2mV typical
at VOUT = 1.22V. At VOUT = 12V, load regulation is:
TheshadedregionofFigure3definestherangeoverwhich
the LT1962 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) = –19.7mV
Bypass Capacitance and Low Noise Performance
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
The LT1962 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 300mA 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 300mA load step in less than
10µs, with total output voltage deviation of less than 2%
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
BYP
= 330pF
C
BYP
≥ 1000pF
1
3
6
9 10
8
2
4
5
7
OUTPUT CAPACITANCE (µF)
1962 F03
Figure 3. Stability
12
LT1962 Series
W U U
APPLICATIO S I FOR ATIO
U
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 capacitance in
a small package, but exhibit strong voltage and tempera-
ture 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.
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.
LT1962-5
COUT = 10µF
CBYP = 0.01µf
I
LOAD = 100mA
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-
VOUT
500µV/DIV
100ms/DIV
1962 F06
20
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
0
Figure 6. Noise Resulting from Tapping on a Ceramic Capacitor
X5R
–20
Thermal Considerations
–40
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:
–60
Y5V
–80
–100
0
8
12 14
2
4
6
10
16
1. Output current multiplied by the input/output voltage
differential: (IOUT)(VIN – VOUT), and
DC BIAS VOLTAGE (V)
1962 F04
Figure 4. Ceramic Capacitor DC Bias Characteristics
2. GND pin current multiplied by the input voltage:
(IGND)(VIN).
40
20
The GND pin current can be found by examining the GND
Pin Current curves in the Typical Performance Character-
istics.Powerdissipationwillbeequaltothesumofthetwo
components listed above.
X5R
0
–20
–40
The LT1962 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.
Y5V
–60
–80
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
–100
50
TEMPERATURE (°C)
100 125
–50 –25
0
25
75
1962 F05
Figure 5. Ceramic Capacitor Temperature Characteristics
13
LT1962 Series
W U U
U
APPLICATIO S I FOR ATIO
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 + 35.3°C = 85.3°C
Protection Features
The LT1962 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.
The following table lists 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. Measured Thermal Resistance
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.
COPPER AREA
THERMAL RESISTANCE
TOPSIDE* BACKSIDE
BOARD AREA (JUNCTION-TO-AMBIENT)
2500mm2
1000mm2
225mm2
100mm2
50mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
2500mm2
110°C/W
115°C/W
120°C/W
130°C/W
140°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
The output of the LT1962 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 500k or higher, limiting current
flow to less than 40µA. 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.
Example: Given an output voltage of 3.3V, an input voltage
range of 4V to 6V, an output current range of 0mA to
100mA 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) = 100mA
VIN(MAX) = 6V
IGND at (IOUT = 100mA, VIN = 6V) = 2mA
So,
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.
P = 100mA(6V – 3.3V) + 2mA(6V) = 0.28W
The thermal resistance will be in the range of 110°C/W to
140°C/W depending on the copper area. So the junction
temperature rise above ambient will be approximately
equal to:
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
0.28W(125°C/W) = 35.3°C
The maximum junction temperature will then be equal to
the maximum junction temperature rise above ambient
plus the maximum ambient temperature or:
14
LT1962 Series
W U U
APPLICATIO S I FOR ATIO
U
fromthe1.22Vreferencewhentheoutputisforcedto20V.
The top resistor of the resistor divider must be chosen to
limitthecurrentintotheADJpintolessthan5mAwhenthe
ADJpinisat7V. The13VdifferencebetweenOUTandADJ
pin divided by the 5mA maximum current into the ADJ pin
yields a minimum top resistor value of 2.6k.
orasecondregulatorcircuit.ThestateoftheSHDNpinwill
have no effect on the reverse output current when the
output is pulled above the input.
100
T
= 25°C
IN
LT1962
J
V
90
80
70
60
50
= 0V
CURRENT FLOWS
INTO OUTPUT PIN
V
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.
= V
(LT1962)
OUT
ADJ
LT1962-1.5
LT1962-1.8
LT1962-2.5
40
30
LT1962-3
LT1962-3.3
20
10
0
LT1962-5
When the IN pin of the LT1962 is forced below the OUT pin
or the OUT pin is pulled above the IN pin, input current will
typicallydroptolessthan2µA. Thiscanhappeniftheinput
of the device is connected to a discharged (low voltage)
battery and the output is held up by either a backup battery
0
1
2
3
4
5
6
7
8
9
10
OUTPUT VOLTAGE (V)
1962 F07
Figure 7. Reverse Output Current
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 ± 0.004*
(3.00 ± 0.102)
8
7
6
5
0.118 ± 0.004**
(3.00 ± 0.102)
0.193 ± 0.006
(4.90 ± 0.15)
1
2
3
4
0.043
(1.10)
MAX
0.034
(0.86)
REF
0.007
(0.18)
0° – 6° TYP
SEATING
PLANE
0.009 – 0.015
(0.22 – 0.38)
0.021 ± 0.006
(0.53 ± 0.015)
0.005 ± 0.002
(0.13 ± 0.05)
0.0256
(0.65)
BSC
MSOP (MS8) 1100
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
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
LT1962 Series
U
TYPICAL APPLICATIO S
Adjustable Current Source
Paralleling of Regulators for Higher Output Current
R1
0.1Ω
R5
0.1Ω
3.3V
IN
OUT
FB
300mA
IN
OUT
LT1962-2.5
SHDN FB
GND
+
+
+
V
C1
10µF
C1
10µF
C2
10µF
IN
>2.7V
V
> 3.7V
R1*
1k
LOAD
IN
C4
0.01µF
LT1962-3.3
SHDN
BYP
R2
40.2k
R6
2.2k
R7
100k
LT1004-1.2
GND
R2
0.1Ω
R3
2k
R4
2.2k
IN
OUT
C5
C3
0.33µF
–
LT1962
0.01µF R6
2k
BYP
ADJ
*ADJUST R1 FOR 0mA TO 300mA
CONSTANT CURRENT
1/2 LT1490
1962 TA04
SHDN
SHDN
+
GND
R7
C2
1µF
1.21k
R3
2.2k
R4
2.2k
8
3
2
R5
10k
+
1
1/2 LT1490
–
4
1962 TA03
C3
0.01µF
RELATED PARTS
PART NUMBER
LT1120
LT1121
LT1129
LT1175
LT1521
LT1529
LTC1627
LT1761
LT1762
LT1763
LT1764
LT1772
LT1963
DESCRIPTION
125mA Low Dropout Regulator with 20µA I
COMMENTS
Includes 2.5V Reference and Comparator
Q
150mA Micropower Low Dropout Regulator
700mA Micropower Low Dropout Regulator
500mA Negative Low Dropout Micropower Regulator
30µA I , SOT-223 Package
Q
50µA Quiescent Current
45µA I , 0.26V Dropout Voltage, SOT-223 Package
Q
300mA Low Dropout Micropower Regulator with Shutdown
3A Low Dropout Regulator with 50µA I
15µA I , Reverse Battery Protection
Q
500mV Dropout Voltage
Burst ModeTM Operation, Monolithic, 100% Duty Cycle
Q
High Efficiency Synchronous Step-Down Switching Regulator
100mA, Low Noise, Low Dropout Micropower Regulator in SOT-23
150mA, Low Noise, LDO Micropower Regulator
20µA Quiescent Current, 20µV
25µA Quiescent Current, 20µV
30µA Quiescent Current, 20µV
Noise
Noise
Noise
Noise
RMS
RMS
RMS
500mA, Low Noise, LDO Micropower Regulator
3A, Fast Transient Response Low Dropout Regulator
Constant Frequency Current Mode Step-Down DC/DC Controller
1.5A, Fast Transient Response Low Dropout Regulator
340mV Dropout Voltage, 40µV
RMS
Up to 94% Efficiency, SOT-23 Package, 100% Duty Cycle
SO-8, SOT-223 Packages
Burst Mode is a trademark of Linear Technology Corporation.
sn1962 1962fas LT/TP 0101 2K REV A • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 2000
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
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