LINER LT1962EMS8-3 300ma, low noise, micropower ldo regulator Datasheet

LT1962 Series
300mA, Low Noise,
Micropower
LDO Regulators
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FEATURES
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DESCRIPTIO
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
Reverse Battery Protection
No Reverse Current
Overcurrent and Overtemperature Protected
8-Lead MSOP Package
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APPLICATIO S
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Cellular Phones
Battery-Powered Systems
Noise-Sensitive Instrumentation Systems
The LT ®1962 series are micropower, low noise, low
dropout regulators. The devices are capable of supplying
300mA of output current with a dropout voltage of 270mV.
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.
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.
Internal protection circuitry includes reverse battery protection, current limiting, thermal limiting and reverse current 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 regulators are available in the 8-lead MSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO
Dropout Voltage
400
3.3V Low Noise Regulator
IN
OUT
1µF
+
SENSE
LT1962-3.3
SHDN
GND
3.3V AT 300mA
20µVRMS NOISE
10µF
0.01µF
BYP
1962 TA01
DROPOUT VOLTAGE (mV)
VIN
3.7V TO
20V
350
300
250
200
150
100
50
0
0
50
100
150
200
LOAD CURRENT (mA)
250
300
1962 TA02
1
LT1962 Series
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AXI U
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ABSOLUTE
RATI GS
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PACKAGE/ORDER I FOR ATIO
(Note 1)
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
(Note 3) ............................................ – 40°C to 125°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
TOP VIEW
OUT
SENSE/ADJ*
BYP
GND
1
2
3
4
8
7
6
5
IN
NC
NC
SHDN
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
LT1962EMS8
LT1962EMS8-1.5
LT1962EMS8-1.8
LT1962EMS8-2.5
LT1962EMS8-3
LT1962EMS8-3.3
LT1962EMS8-5
MS8 PART MARKING
SEE THE APPLICATIONS
INFORMATION SECTION
FOR ADDITIONAL
INFORMATION ON
THERMAL RESISTANCE
LTPQ
LTPS
LTPR
LTML
LTSZ
LTTA
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
Minimum Operating Voltage
(LT1962)
ILOAD = 300mA (Notes 4, 12)
●
Regulated Output Voltage
(Notes 4, 5)
LT1962-1.5
VIN = 2V, ILOAD = 1mA
2.5V < VIN < 20V, 1mA < ILOAD < 300mA
●
VIN = 2.3V, ILOAD = 1mA
2.8V < VIN < 20V, 1mA < ILOAD < 300mA
LT1962-1.8
LT1962-2.5
LT1962-3
LT1962-3.3
LT1962-5
MIN
TYP
MAX
UNITS
1.8
2.3
V
1.485
1.462
1.500
1.500
1.515
1.538
V
V
●
1.782
1.755
1.800
1.800
1.818
1.845
V
V
VIN = 3V, ILOAD = 1mA
3.5V < VIN < 20V, 1mA < ILOAD < 300mA
●
2.475
2.435
2.500
2.500
2.525
2.565
V
V
VIN = 3.5V, ILOAD = 1mA
4V < VIN < 20V, 1mA < ILOAD < 300mA
●
2.970
2.925
3.000
3.000
3.030
3.075
V
V
VIN = 3.8V, ILOAD = 1mA
4.3V < VIN < 20V, 1mA < ILOAD < 300mA
●
3.267
3.220
3.300
3.300
3.333
3.380
V
V
VIN = 5.5V, ILOAD = 1mA
6V < VIN < 20V, 1mA < ILOAD < 300mA
●
4.950
4.875
5.000
5.000
5.050
5.125
V
V
VIN = 2V, ILOAD = 1mA
2.3V < VIN < 20V, 1mA < ILOAD < 300mA
●
1.208
1.190
1.220
1.220
1.232
1.250
V
V
1
1
1
1
1
1
1
5
5
5
5
5
5
5
mV
mV
mV
mV
mV
mV
mV
3
8
15
mV
mV
4
9
18
mV
mV
ADJ Pin Voltage
(Notes 4, 5)
LT1962
Line Regulation
LT1962-1.5
LT1962-1.8
LT1962-2.5
LT1962-3
LT1962-3.3
LT1962-5
LT1962 (Note 4)
∆VIN = 2V to 20V, ILOAD = 1mA
∆VIN = 2.3V to 20V, ILOAD = 1mA
∆VIN = 3V to 20V, ILOAD = 1mA
∆VIN = 3.5V to 20V, ILOAD = 1mA
∆VIN = 3.8V to 20V, ILOAD = 1mA
∆VIN = 5.5V to 20V, ILOAD = 1mA
∆VIN = 2V to 20V, ILOAD = 1mA
●
●
●
●
●
●
●
Load Regulation
LT1962-1.5
VIN = 2.5V, ∆ILOAD = 1mA to 300mA
VIN = 2.5V, ∆ILOAD = 1mA to 300mA
●
VIN = 2.8V, ∆ILOAD = 1mA to 300mA
VIN = 2.8V, ∆ILOAD = 1mA to 300mA
●
LT1962-1.8
2
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
Load Regulation
LT1962-2.5
LT1962-3
LT1962-3.3
LT1962-5
LT1962 (Note 4)
MIN
VIN = 3.5V, ∆ILOAD = 1mA to 300mA
VIN = 3.5V, ∆ILOAD = 1mA to 300mA
●
VIN = 4V, ∆ILOAD = 1mA to 300mA
VIN = 4V, ∆ILOAD = 1mA to 300mA
●
VIN = 4.3V, ∆ILOAD = 1mA to 300mA
VIN = 4.3V, ∆ILOAD = 1mA to 300mA
●
VIN = 6V, ∆ILOAD = 1mA to 300mA
VIN = 6V, ∆ILOAD = 1mA to 300mA
●
VIN = 2.3V, ∆ILOAD = 1mA to 300mA
VIN = 2.3V, ∆ILOAD = 1mA to 300mA
●
Dropout Voltage
VIN = VOUT(NOMINAL)
ILOAD = 10mA
ILOAD = 10mA
●
(Notes 6, 7, 12)
ILOAD = 50mA
ILOAD = 50mA
●
ILOAD = 100mA
ILOAD = 100mA
●
ILOAD = 300mA
ILOAD = 300mA
●
GND Pin Current
VIN = VOUT(NOMINAL)
(Notes 6, 8)
ILOAD = 0mA
ILOAD = 1mA
ILOAD = 50mA
ILOAD = 100mA
ILOAD = 300mA
●
●
●
●
●
Output Voltage Noise
COUT = 10µF, CBYP = 0.01µF, ILOAD = 300mA, BW = 10Hz to 100kHz
ADJ Pin Bias Current
(Notes 4, 9)
Shutdown Threshold
VOUT = Off to On
VOUT = On to Off
TYP
MAX
5
12
25
mV
mV
7
15
30
mV
mV
7
17
33
mV
mV
12
25
50
mV
mV
2
6
12
mV
mV
0.10
0.15
0.21
V
V
0.15
0.20
0.28
V
V
0.18
0.24
0.33
V
V
0.27
0.33
0.43
V
V
30
65
1.1
2
8
75
120
1.6
3
12
µA
µA
mA
mA
mA
µVRMS
20
●
●
0.25
UNITS
30
100
nA
0.8
0.65
2
V
V
SHDN Pin Current
(Note 10)
VSHDN = 0V
VSHDN = 20V
0.01
1
0.5
5
µA
µA
Quiescent Current in Shutdown
VIN = 6V, VSHDN = 0V
0.1
1
µA
Ripple Rejection
VIN – VOUT = 1.5V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz,
ILOAD = 300mA
Current Limit
VIN = 7V, VOUT = 0V
VIN = VOUT(NOMINAL) + 1V, ∆VOUT = – 0.1V
●
Input Reverse Leakage Current
VIN = – 20V, VOUT = 0V
●
Reverse Output Current
(Note 11)
LT1962-1.5
LT1962-1.8
LT1962-2.5
LT1962-3
LT1962-3.3
LT1962-5
LT1962 (Note 4)
VOUT = 1.5V, VIN < 1.5V
VOUT = 1.8V, VIN < 1.8V
VOUT = 2.5V, VIN < 2.5V
VOUT = 3V, VIN < 3V
VOUT = 3.3V, VIN < 3.3V
VOUT = 5V, VIN < 5V
VOUT = 1.22V, VIN < 1.22V
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
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.
55
65
dB
700
mA
mA
320
10
10
10
10
10
10
5
1
mA
20
20
20
20
20
20
10
µA
µA
µA
µA
µA
µA
µA
Note 3: The LT1962 regulators are tested and specified under pulse load
conditions such that TJ ≈ TA. The LT1962 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 4: The LT1962 (adjustable version) is tested and specified for these
conditions with the ADJ pin connected to the OUT pin.
3
LT1962 Series
ELECTRICAL CHARACTERISTICS
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.
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
output voltage will be equal to: VIN – VDROPOUT.
Note 8: GND pin current is tested with VIN = VOUT(NOMINAL) or VIN = 2.3V
(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 9: ADJ pin bias current flows into the ADJ pin.
Note 10: SHDN pin current flows into the SHDN pin. This current is
included in the specification for GND pin current.
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.
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TYPICAL PERFOR A CE CHARACTERISTICS
Guaranteed Dropout Voltage
500
GUARANTEED DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV)
350
TJ = 125°C
300
250
200
TJ = 25°C
150
100
50
0
= TEST POINTS
450
350
TJ ≤ 125°C
400
350
TJ ≤ 25°C
300
250
200
150
100
0
0
50
100
200
250
150
OUTPUT CURRENT (mA)
0
300
IL = 300mA
300
250
IL = 100mA
200
IL = 50mA
150
IL = 10mA
100
50
50
50
250
150
200
100
OUTPUT CURRENT (mA)
IL = 1mA
0
– 50 – 25
300
75
50
25
TEMPERATURE (°C)
0
1962 G02
1962 G01
Quiescent Current
1.532
45
100
125
1962 G03
LT1962-1.8 Output Voltage
LT1962-1.5 Output Voltage
50
1.836
IL = 1mA
1.524
1.827
1.516
1.818
IL = 1mA
35
30
25
20
15
10
5
VIN = 6V
VSHDN = VIN
RL = ∞, IL = 0 (LT1962-1.5/-1.8
/2.5/-3/-3.3/-5)
RL = 250k, IL = 5µA (LT1962)
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
1.508
1.500
1.492
1.484
1.476
100
125
1962 G04
4
OUTPUT VOLTAGE (V)
40
OUTPUT VOLTAGE (V)
QUIESCENT CURRENT (µA)
Dropout Voltage
400
DROPOUT VOTLAGE (mV)
Typical Dropout Voltage
400
1.468
–50
1.809
1.800
1.791
1.782
1.773
–25
50
75
0
25
TEMPERATURE (°C)
100
125
1962 G05
1.764
–50
–25
50
75
0
25
TEMPERATURE (°C)
100
125
1962 G06
LT1962 Series
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TYPICAL PERFOR A CE CHARACTERISTICS
LT1962-2.5 Output Voltage
3.060
IL = 1mA
3.360
IL = 1mA
3.045
3.345
2.52
3.030
3.330
2.51
2.50
2.49
2.48
OUTPUT VOTLAGE (V)
2.53
OUTPUT VOTLAGE (V)
OUTPUT VOTLAGE (V)
2.54
LT1962-3.3 Output Voltage
LT1962-3 Output Voltage
3.015
3.000
2.985
2.970
2.955
2.47
2.46
– 50 – 25
75
50
25
TEMPERATURE (°C)
100
0
75
50
25
TEMPERATURE (°C)
0
100
LT1962-5 Output Voltage
3.270
125
3.240
– 50 – 25
5.050
1.230
5.025
5.000
4.975
4.950
75
50
25
TEMPERATURE (°C)
100
0
125
800
IL = 1mA
1.225
1.220
1.215
1.210
100
400
300
200
VSHDN = 0V
500
400
300
200
VSHDN = 0V
8
9
10
1962 G13
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1962 G12
800
TJ = 25°C
RL = ∞
700
600
500
400
300
200
VSHDN = 0V
100
VSHDN = VIN
0
0
1
LT1962-3 Quiescent Current
600
100
VSHDN = VIN
VSHDN = 0V
VSHDN = VIN
0
QUIESCENT CURRENT (µA)
500
3 4 5 6 7
INPUT VOLTAGE (V)
200
125
TJ = 25°C
RL = ∞
700
QUIESCENT CURRENT (µA)
600
2
300
LT1962-2.5 Quiescent Current
TJ = 25°C
RL = ∞
1
400
0
75
50
25
TEMPERATURE (°C)
0
800
100
500
1962 G11
LT1962-1.8 Quiescent Current
700
600
100
1.200
– 50 – 25
125
TJ = 25°C
RL = ∞
700
1962 G10
800
100
LT1962-1.5 Quiescent Current
1.205
4.900
– 50 – 25
75
50
25
TEMPERATURE (°C)
0
1962 G09
QUIESCENT CURRENT (µA)
1.235
ADJ PIN VOTLAGE (V)
OUTPUT VOTLAGE (V)
1.240
IL = 1mA
4.925
QUIESCENT CURRENT (µA)
3.285
LT1962 ADJ Pin Voltage
5.075
0
3.300
1962 G08
1962 G07
5.100
3.315
3.255
2.940
– 50 – 25
125
IL = 1mA
VSHDN = VIN
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1962 G14
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1962 G15
5
LT1962 Series
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TYPICAL PERFOR A CE CHARACTERISTICS
TJ = 25°C
RL = ∞
600
500
400
300
200
VSHDN = 0V
100
600
500
400
300
200
VSHDN = 0V
100
VSHDN = VIN
0
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
750
500
RL = 150Ω
IL = 10mA*
250
9
RL = 1.5k
IL = 1mA*
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
750
500
RL = 180Ω
IL = 10mA*
RL = 1.8k
IL = 1mA*
10
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
1250
750
RL = 300Ω
IL = 10mA*
500
250
RL = 3k
IL = 1mA*
8
9
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1962 G22
RL = 2.5k
IL = 1mA*
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
750
10
LT1962-5 GND Pin Current
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 5V
1250
RL = 330Ω
IL = 10mA*
500
9
1962 G21
1500
RL = 3.3k
IL = 1mA*
RL = 100Ω
IL = 50mA*
1000
750
RL = 500Ω
IL = 10mA*
500
RL = 5k
IL = 1mA*
250
0
1
RL = 250Ω
IL = 10mA*
500
10
RL = 66Ω
IL = 50mA*
1000
250
0
0
750
250
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3.3V
1250
GND PIN CURRENT (µA)
RL = 60Ω
IL = 50mA*
RL = 50Ω
IL = 50mA*
1000
LT1962-3.3 GND Pin Current
1500
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3V
1000
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 2.5V
1962 G20
LT1962-3 GND Pin Current
1250
6 8 10 12 14 16 18 20
INPUT VOLTAGE (V)
0
0
1962 G19
1500
4
1500
GND PIN CURRENT (µA)
2
2
1962 G18
0
1
VSHDN = 0V
0
LT1962-2.5 GND Pin Current
RL = 36Ω
IL = 50mA*
1000
250
0
0
10
10
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.8V
1250
GND PIN CURRENT (µA)
GND PIN CURRENT (µA)
RL = 30Ω
IL = 50mA*
1000
15
LT1962-1.8 GND Pin Current
1500
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.5V
1250
20
1962 G17
LT1962-1.5 GND Pin Current
1500
25
0
0
GND PIN CURRENT (µA)
1
VSHDN = VIN
30
5
VSHDN = VIN
1962 G16
GND PIN CURRENT (µA)
TJ = 25°C
35 RL = 250k
0
0
6
LT1962 Quiescent Current
40
TJ = 25°C
RL = ∞
700
QUIESCENT CURRENT (µA)
700
QUIESCENT CURRENT (µA)
LT1962-5 Quiescent Current
800
QUIESCENT CURRENT (µA)
LT1962-3.3 Quiescent Current
800
0
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1962 G23
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1962 G24
LT1962 Series
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TYPICAL PERFOR A CE CHARACTERISTICS
1500
8
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.22V
1250
RL = 24.4Ω
IL = 50mA*
1000
750
500
RL = 1.22k
IL = 1mA*
RL = 122Ω
IL = 10mA*
250
0
6
7
RL = 5Ω
IL = 300mA*
5
RL = 7.5Ω
IL = 200mA*
4
3
RL = 15Ω
IL = 100mA*
2
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
9
8
0
10
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
3
RL = 25Ω
IL = 100mA*
2
1
0
0
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
RL = 10Ω
IL = 300mA*
6
5
RL = 15Ω
IL = 200mA*
4
3
RL = 30Ω
IL = 100mA*
2
10
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
1
RL = 4.07Ω
IL = 300mA*
5
4
RL = 6.1Ω
IL = 200mA*
3
2
RL = 12.2Ω
IL = 100mA*
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
9
10
1962 G31
RL = 33Ω
IL = 100mA*
2
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
8
0
1
2
3 4 5 6 7
INPUT VOLTAGE (V)
9
10
1962 G30
8
VIN = VOUT(NOMINAL) + 1V
7
6
5
4
3
2
1
0
0
3
GND Pin Current vs ILOAD
6
1
0
RL = 16.5Ω
IL = 200mA*
4
0
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
RL = 50Ω
IL = 100mA*
RL = 11Ω
IL = 300mA*
5
10
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.22V
7
3
2
6
LT1962 GND Pin Current
RL = 25Ω
IL = 200mA*
4
10
0
1
8
TJ = 25°C
7 VIN = VSHDN
*FOR VOUT = 5V
9
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3.3V
7
1962 G29
LT1962-5 GND Pin Current
5
8
1
0
8
RL = 16.7Ω
IL = 300mA*
3 4 5 6 7
INPUT VOLTAGE (V)
LT1962-3.3 GND Pin Current
1962 G28
6
2
8
0
1
1
1962 G27
1
0
RL = 18Ω
IL = 100mA*
2
10
GND PIN CURRENT (mA)
GND PIN CURRENT (mA)
RL = 12.5Ω
IL = 200mA*
4
9
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 3V
7
RL = 8.33Ω
IL = 300mA*
5
3
LT1962-3 GND Pin Current
8
6
RL = 9Ω
IL = 200mA*
4
1962 G26
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 2.5V
7
5
0
0
LT1962-2.5 GND Pin Current
8
RL = 6Ω
IL = 300mA*
6
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.8V
1
1962 G25
GND PIN CURRENT (mA)
8
1
0
GND PIN CURRENT (mA)
LT1962-1.8 GND Pin Current
TJ = 25°C
VIN = VSHDN
*FOR VOUT = 1.5V
7
GND PIN CURRENT (mA)
GND PIN CURRENT (µA)
LT1962-1.5 GND Pin Current
GND PIN CURRENT (mA)
LT1962 GND Pin Current
8
9
10
1962 G32
0
0
50
100
200
250
150
OUTPUT CURRENT (mA)
300
1962 G33
7
LT1962 Series
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TYPICAL PERFOR A CE CHARACTERISTICS
SHDN Pin Threshold (On-to-Off)
IL = 1mA
SHDN Pin Input Current
1.4
0.9
0.8
SHDN PIN THRESHOLD (V)
SHDN PIN THRESHOLD (V)
0.9
SHDN Pin Threshold (Off-to-On)
1.0
0.7
0.6
0.5
0.4
0.3
0.2
0.1
SHDN PIN INPUT CURRENT (µA)
1.0
0.8
0.7
IL = 300mA
0.6
IL = 1mA
0.5
0.4
0.3
0.2
0.1
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
50
25
0
75
TEMPERATURE (°C)
100
1962 G34
1.0
0.8
0.6
0.4
75
50
25
TEMPERATURE (°C)
100
20
15
10
0.6
0.5
0.4
0.3
0.1
0
50
25
75
0
TEMPERATURE (°C)
100
125
0
Reverse Output Current
0.4
0.2
TJ = 25°C
90 VIN = 0V
CURRENT FLOWS
80 INTO OUTPUT PIN
70 VOUT = VADJ (LT1962)
Reverse Output Current
50
40
LT1962-3
30
LT1962-3.3
20
10
100
125
1962 G40
LT1962
LT1962-1.5
LT1962-1.8
LT1962-2.5
60
0
VIN = 0V
VOUT = 1.22V (LT1962)
25 VOUT = 1.5V (LT1962-1.5)
VOUT = 1.8V (LT1962-1.8)
VOUT = 2.5V (LT1962-2.5)
20 V
OUT = 3V (LT1962-3)
VOUT = 3.3V (LT1962-3.3)
V
= 5V (LT1962-5)
15 OUT
LT1962-1.5/-1.8/-2.5/-3/-3.3/-5
10
5
LT1962-5
0
1
2
7
6
30
REVERSE OUTPUT CURRENT (µA)
REVERSE OUTPUT CURRENT (µA)
0.6
4
3
2
5
INPUT VOLTAGE (V)
1962 G39
100
0.8
1
1962 G38
Current Limit
50
25
75
0
TEMPERATURE (°C)
0.7
0.2
1962 G37
1.0
10
0.8
25
0
–50 –25
125
VIN = 7V
VOUT = 0V
9
VOUT = 0V
0.9
5
0
7 8
3
4 5 6
SHDN PIN VOLTAGE (V)
Current Limit
1.0
CURRENT LIMIT (A)
ADJ PIN BIAS CURRENT (nA)
SHDN PIN INPUT CURRENT (µA)
1.2
2
1
1962 G36
30
0.2
CURRENT LIMIT (A)
0.2
0
VSHDN = 20V
1.4
8
0.4
125
35
0
–50 –25
0.6
ADJ Pin Bias Current
SHDN Pin Input Current
1.2
0.8
1962 G35
1.6
0
– 50 – 25
1.0
0
0
–50 –25
125
1.2
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
LT1962
9
10
1962 F07
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
1962 G42
LT1962 Series
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TYPICAL PERFOR A CE CHARACTERISTICS
Input Ripple Rejection
Input Ripple Rejection
50
COUT = 10µF
40
30
COUT = 3.3µF
20
CBYP = 0.01µF
70
10
0
100
100k
1k
10k
FREQUENCY (Hz)
1M
60
50
CBYP = 100pF
40
30
20 IL = 300mA
VIN = VOUT(NOMINAL) + 1V
10 + 50mVRMS RIPPLE
COUT = 10µF
0
100
10
1k
10k
FREQUENCY (Hz)
100k
LOAD REGULATION (mV)
MINIMUM INPUT VOLTAGE (V)
LT1962
0
1.50
IL = 1mA
1.25
1.00
0.75
0.50
LT1962-1.8
LT1962-1.5
–5
LT1962-3.3
LT1962-3
LT1962-2.5
–10
–15
LT1962-5
–20
VIN = VOUT(NOMINAL) + 1V
∆IL = 1mA TO 300mA
–25
50
25
75
–50 –25
0
TEMPERATURE (°C)
0.25
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
125
100
100
1962 G46
140
CBYP = 1000pF
1
CBYP = 100pF
LT1962
CBYP = 0.01µF
0.1
OUTPUT NOISE (µVRMS)
OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz)
160
10
IL = 300mA
COUT = 10µF
CBYP = 0
LT1962-5
LT1962-3.3
LT1962-3
1
LT1962
0.1
LT1962-2.5
LT1962-1.8
LT1962-1.5
0.01
125
10
100
1k
10k
FREQUENCY (Hz)
RMS Output Noise
vs Load Current (10Hz to 100kHz)
160
140
120
LT1962-5
LT1962-3
LT1962-3.3
80
LT1962-2.5
LT1962-1.8
LT1962-1.5
60
40
100k
1962 G48
IL = 300mA
COUT = 10µF
f = 10Hz to 100kHz
100
125
1962 G45
RMS Output Noise
vs Bypass Capacitor
IL = 300mA
COUT = 10µF
LT1962-5
100
1962 G47
Output Noise Spectral Density
10
56
IL = 300mA
54 VIN = VOUT(NOMINAL) + 1V
+ 0.5VP-P RIPPLE AT f = 120Hz
52
75
0
50
25
– 50 – 25
Output Noise Spectral Density
5
IL = 300mA
1.75
58
Load Regulation
VOUT = 1.22V
2.00
60
1962 G44
LT1962 Minimum Input Voltage
2.25
62
TEMPERATURE (°C)
1962 G43
2.50
64
1M
OUTPUT NOISE SPECTRIAL DENSITY (µV/√Hz)
10
66
CBYP = 1000pF
OUTPUT NOISE (µVRMS)
RIPPLE REJECTION (dB)
60
68
RIPPLE REJECTION (dB)
IL = 300mA
VIN = VOUT(NOMINAL) + 1V
+ 50mVRMS RIPPLE
CBYP = 0
70
Ripple Rejection
80
RIPPLE REJECTION (dB)
80
LT1962
20
COUT = 10µF
CBYP = 0µF
CBYP = 0.01µF
120
LT1962-5
100
80
60
LT1962
40
LT1962-5
20
LT1962
0
0.01
10
100
1k
10k
FREQUENCY (Hz)
100k
10
100
1k
10k
CBYP (pF)
1962 G49
1962 G50
0
0.01
0.1
1
10
100
LOAD CURRENT (mA)
1000
1962 G51
9
LT1962 Series
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TYPICAL PERFOR A CE CHARACTERISTICS
LT1962-5 10Hz to 100kHz
Output Noise (CBYP = 100pF)
LT1962-5 10Hz to 100kHz
Output Noise (CBYP = 0)
VOUT
100µV/DIV
LT1962-5 10Hz to 100kHz
Output Noise (CBYP = 1000pF)
VOUT
100µV/DIV
VOUT
100µV/DIV
COUT = 10µF
IL = 300mA
1ms/DIV
COUT = 10µF
IL = 300mA
1962 G52
1ms/DIV
COUT = 10µF
IL = 300mA
1962 G53
LT1962-5 Transient Response
COUT = 10µF
IL = 300mA
1ms/DIV
1962 G55
OUTPUT VOLTAGE
DEVIATION (mV)
VIN = 6V
0.4 CIN = 10µF
COUT = 10µF
0.2 C
BYP = 0
0
–0.2
–0.4
300
200
100
0
0
1962 G54
LT1962-5 Transient Response
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
TIME (ms)
1962 G56
LOAD CURRENT (mA)
VOUT
100µV/DIV
LOAD CURRENT (mA)
OUTPUT VOLTAGE
DEVIATION (V)
LT1962-5 10Hz to 100kHz
Output Noise (CBYP = 0.01µF)
1ms/DIV
VIN = 6V
CIN = 10µF
COUT = 10µF
CBYP = 0.01µF
0.10
0.05
0
–0.05
–0.10
300
200
100
0
0
50 100 150 200 250 300 350 400 450 500
TIME (µs)
1962 G57
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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.
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
10
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 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.
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
LT1962 Series
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PI FU CTIO S
8
IN
OUT
1
RP
LT1962
+
5
SHDN
VIN
SENSE
+
2
LOAD
GND
4
RP
1962 F01
Figure 1. Kelvin Sense Connection
pin. The ADJ pin voltage is 1.22V referenced to ground and
the output voltage range is 1.22V to 20V.
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
SHDN pin can be driven either by 5V logic or opencollector logic with a pull-up resistor. The pull-up resistor
is required to supply the pull-up current of the opencollector 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.
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.
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.
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APPLICATIO S I FOR ATIO
The LT1962 series are 300mA low dropout regulators with
micropower quiescent current and shutdown. The devices
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
0.01µF reference bypass capacitor. Additionally, the reference 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
quiescent current, the LT1962 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 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 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 LT1962 has an output
voltage range of 1.22V 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 ADJ pin voltage
at 1.22V referenced to ground. The current in R1 is then
equal to 1.22V/R1 and the current in R2 is the current in R1
11
LT1962 Series
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APPLICATIO S I FOR ATIO
OUT
LT1962
VOUT
R2
+
ADJ
GND
R1
1962 F02
 R2
VOUT = 1.22V  1 +  + (IADJ )(R2)
 R1
VADJ = 1.22V
IADJ = 30nA AT 25°C
OUTPUT RANGE = 1.22V TO 20V
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
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 1.22V.
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:
(12V/1.22V)(–2mV) = – 19.7mV
Bypass Capacitance and Low Noise Performance
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%
12
(see LT1962-5 Transient Response in the Typical Performance Characteristics). However, regulator start-up time
is inversely proportional to the size of the bypass capacitor, slowing to 15ms with a 0.01µF bypass capacitor and
10µF output capacitor.
Output Capacitance and Transient Response
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 capacitors. 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 increase the effective output capacitor value. With larger
capacitors used to bypass the reference (for low noise
operation), larger values of output capacitance are needed.
For 100pF of bypass capacitance, 4.7µF of output capacitor is recommended. With a 1000pF bypass capacitor or
larger, a 6.8µF output capacitor is recommended.
The shaded region of Figure 3 defines the range over which
the LT1962 regulators are stable. The minimum ESR
needed is defined by the amount of bypass capacitance
used, while the maximum ESR is 3Ω.
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
4.0
3.5
3.0
STABLE REGION
2.5
ESR (Ω)
IN
VIN
2.0
CBYP = 0
CBYP = 100pF
1.5
CBYP = 330pF
CBYP ≥ 1000pF
1.0
0.5
0
1
3
2
4 5 6 7 8 9 10
OUTPUT CAPACITANCE (µF)
1962 F03
Figure 3. Stability
LT1962 Series
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APPLICATIO S I FOR ATIO
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 temperature 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.
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.
LT1962-5
COUT = 10µF
CBYP = 0.01µf
ILOAD = 100mA
VOUT
500µV/DIV
100ms/DIV
20
1962 F06
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
0
Figure 6. Noise Resulting from Tapping on a Ceramic Capacitor
CHANGE IN VALUE (%)
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
2
4
14
8
6
10 12
DC BIAS VOLTAGE (V)
16
1962 F04
Figure 4. Ceramic Capacitor DC Bias Characteristics
40
CHANGE IN VALUE (%)
X5R
–20
–40
Y5V
–60
–80
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
–100
–50 –25
50
25
75
0
TEMPERATURE (°C)
2. GND pin current multiplied by the input voltage:
(IGND)(VIN).
The GND pin current can be found by examining the GND
Pin Current curves in the Typical Performance Characteristics. Power dissipation will be equal to the sum of the two
components listed above.
20
0
1. Output current multiplied by the input/output voltage
differential: (IOUT)(VIN – VOUT), and
100
125
1962 F05
Figure 5. Ceramic Capacitor Temperature Characteristics
The LT1962 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.
13
LT1962 Series
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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 generated by power devices.
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
COPPER AREA
THERMAL RESISTANCE
TOPSIDE*
BACKSIDE
2
2
2500mm
2
1000mm
2
BOARD AREA
2500mm
2
2500mm
2
(JUNCTION-TO-AMBIENT)
2
110°C/W
2
115°C/W
2
2500mm
2500mm
225mm
2500mm
2500mm
120°C/W
100mm2
2500mm2
2500mm2
130°C/W
2
2
140°C/W
50mm
2
2500mm
2500mm
*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
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,
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:
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
TJMAX = 50°C + 35.3°C = 85.3°C
Protection Features
The LT1962 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 (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.
The output of the LT1962 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 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.
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 100k) 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
LT1962 Series
U
W
U U
APPLICATIO S I FOR ATIO
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.
100
REVERSE OUTPUT CURRENT (µA)
from the 1.22V 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
pin 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 7.
30
LT1962
LT1962-3.3
20
10
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
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
U
PACKAGE DESCRIPTIO
TJ = 25°C
90 VIN = 0V
CURRENT FLOWS
80 INTO OUTPUT PIN
70 VOUT = VADJ (LT1962)
LT1962-1.5
60
LT1962-1.8
50
LT1962-2.5
40
LT1962-3
0
LT1962-5
0
1
2
3 4 5 6 7 8
OUTPUT VOLTAGE (V)
9
10
1962 F07
Figure 7. Reverse Output Current
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
0.007
(0.18)
0.034
(0.86)
REF
0° – 6° TYP
0.021 ± 0.006
(0.53 ± 0.015)
SEATING
PLANE
0.009 – 0.015
(0.22 – 0.38)
0.0256
(0.65)
BSC
0.005 ± 0.002
(0.13 ± 0.05)
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LT1962 Series
U
TYPICAL APPLICATIO S
Adjustable Current Source
Paralleling of Regulators for Higher Output Current
R1
0.1Ω
R5
0.1Ω
+
VIN
>2.7V
IN
C1
10µF
R1*
1k
OUT
R2
40.2k
R3
2k
LOAD
LT1962-2.5
SHDN
LT1004-1.2
+
R6
2.2k
VIN > 3.7V
IN
+
FB
C1
10µF
C4
0.01µF
LT1962-3.3
FB
3.3V
300mA
C2
10µF
SHDN
BYP
GND
R7
100k
GND
OUT
R2
0.1Ω
R4
2.2k
IN
–
OUT
C3
0.33µF
C5
0.01µF
LT1962
BYP
*ADJUST R1 FOR 0mA TO 300mA
CONSTANT CURRENT
1/2 LT1490
+
1962 TA04
SHDN
SHDN
ADJ
GND
R7
1.21k
C2
1µF
R3
2.2k
R4
2.2k
3
8
+
1/2 LT1490
2
–
R6
2k
1
R5
10k
4
1962 TA03
C3
0.01µF
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1120
125mA Low Dropout Regulator with 20µA IQ
Includes 2.5V Reference and Comparator
LT1121
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LT1129
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LT1175
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LT1521
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LTC1627
High Efficiency Synchronous Step-Down Switching Regulator
Burst ModeTM Operation, Monolithic, 100% Duty Cycle
LT1761
100mA, Low Noise, Low Dropout Micropower Regulator in SOT-23
20µA Quiescent Current, 20µVRMS Noise
LT1762
150mA, Low Noise, LDO Micropower Regulator
25µA Quiescent Current, 20µVRMS Noise
LT1763
500mA, Low Noise, LDO Micropower Regulator
30µA Quiescent Current, 20µVRMS Noise
LT1764
3A, Fast Transient Response Low Dropout Regulator
340mV Dropout Voltage, 40µVRMS Noise
LT1772
Constant Frequency Current Mode Step-Down DC/DC Controller
Up to 94% Efficiency, SOT-23 Package, 100% Duty Cycle
LT1963
1.5A, Fast Transient Response Low Dropout Regulator
SO-8, SOT-223 Packages
Burst Mode is a trademark of Linear Technology Corporation.
16
Linear Technology Corporation
sn1962 1962fas LT/TP 0101 2K REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
 LINEAR TECHNOLOGY CORPORATION 2000
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