LT1461-2.5
Micropower Precision
Low Dropout Series
Voltage Reference
FEATURES
s
s
s
s
s
s
s
s
s
s
s
DESCRIPTIO
Trimmed to High Accuracy: 0.04% Max
Low Drift: 3ppm/
°
C Max
Low Supply Current: 50
µ
A Max
Temperature Coefficient Guaranteed to 125°C
High Output Current: 50mA Min
Low Dropout Voltage: 300mV Max
Excellent Thermal Regulation
Power Shutdown
Thermal Limiting
Operating Temperature Range: – 40°C to 125°C
Available in SO-8 Package
APPLICATIO S
s
s
s
s
A/D and D/A Converters
Precision Regulators
Handheld Instruments
Power Supplies
The LT
®
1461 is a low dropout micropower bandgap refer-
ence that combines very high accuracy and low drift with low
supply current and high output drive. This series reference
uses advanced curvature compensation techniques to obtain
low temperature coefficient and trimmed precision thin-film
resistors to achieve high output accuracy. The LT1461 draws
only 35µA of supply current, making it ideal for low power and
portable applications, however its high 50mA output drive
makes it suitable for higher power requirements, such as
precision regulators.
In low power applications, a dropout voltage of less than
300mV ensures maximum battery life while maintaining full
reference performance. Line regulation is nearly immeasur-
able, while the exceedingly good load and thermal regulation
will not add significantly to system error budgets. The
shutdown feature can be used to switch full load currents and
can be used for system power down. Thermal shutdown
protects the part from overload conditions.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Basic Connection
V
IN
≥
2.8V
LT1461-2.5
C
IN
1µF
C
L
2µF
1461 TA01
Load Regulation, P
DISS
= 200mW
2.5V
0mA
I
OUT
20mA
V
OUT
LOAD REG
1mV/DIV
U
10ms/DIV
1461 TA02
U
U
1
LT1461-2.5
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
ORDER PART
NUMBER
TOP VIEW
DNC* 1
V
IN
2
SHDN 3
GND 4
8
7
6
5
DNC*
DNC*
V
OUT
DNC*
Input Voltage ........................................................... 20V
Output Short-Circuit Duration ......................... Indefinite
Operating Temperature Range
(Note 2) ........................................... – 40°C to 125°C
Specified Temperature Range
Commercial ............................................ 0°C to 70°C
Industrial ........................................... – 40°C to 85°C
High ................................................. – 40°C to 125°C
Storage Temperature Range (Note 3) ... – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
S8 PACKAGE
8-LEAD PLASTIC SO
*DNC: DO NOT CONNECT
T
JMAX
= 130°C,
θ
JA
= 190°C/ W
LT1461ACS8-2.5
LT1461BCS8-2.5
LT1461CCS8-2.5
LT1461AIS8-2.5
LT1461BIS8-2.5
LT1461CIS8-2.5
LT1461DHS8-2.5
S8 PART MARKING
461A25 61BI25
461B25 61CI25
461C25 61DH25
61AI25
Consult factory for Military grade parts.
AVAILABLE OPTIO S
GRADE
LT1461ACS8-2.5/LT1461AIS8-2.5
LT1461BCS8-2.5/LT1461BIS8-2.5
LT1461CCS8-2.5/LT1461CIS8-2.5
LT1461DHS8-2.5, – 40°C to 125°C
INITIAL
ACCURACY (%)
0.04%
0.06%
0.08%
0.15%
MAXIMUM TEMPERATURE
COEFFICIENT (ppm/
°
C)
3
7
12
20
The
q
denotes specifications which apply over the specified temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
– V
OUT
= 0.5V, Pin 3 = 2.4V, C
L
= 2µF, unless otherwise specified.
PARAMETER
Output Voltage (Note 4)
CONDITIONS
LT1461ACS8-2.5/LT1461AIS8-2.5
LT1461BCS8-2.5/LT1461BIS8-2.5
LT1461CCS8-2.5/LT1461CIS8-2.5
LT1461DHS8-2.5
Output Voltage Temperature Coefficient (Note 5)
LT1461ACS8-2.5/LT1461AIS8-2.5
LT1461BCS8-2.5/LT1461BIS8-2.5
LT1461CCS8-2.5/LT1461CIS8-2.5
LT1461DHS8-2.5
q
q
q
q
ELECTRICAL CHARACTERISTICS
MIN
2.499
– 0.04
2.4985
– 0.06
2.498
– 0.08
2.49625
– 0.15
TYP
2.500
2.500
2.500
2.500
1
3
5
7
MAX
2.501
0.04
2.5015
0.06
2.502
0.08
2.50375
0.15
3
7
12
20
UNITS
V
%
V
%
V
%
V
%
ppm/°C
ppm/°C
ppm/°C
ppm/°C
2
U
W
U
U
W W
U
W
LT1461-2.5
The
q
denotes specifications which apply over the specified temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
– V
OUT
= 0.5V, Pin 3 = 2.4V, C
L
= 2µF, unless otherwise specified.
PARAMETER
Line Regulation
CONDITIONS
(V
OUT
+ 0.5V)
≤
V
IN
≤
20V
q
ELECTRICAL CHARACTERISTICS
MIN
TYP
2
MAX
8
12
50
30
40
50
UNITS
ppm/V
ppm/V
ppm/V
ppm/mA
ppm/mA
ppm/mA
V
V
V
V
mA
V
µA
V
µA
µA
µA
µA
µA
µV
P-P
ppm
P-P
µV
RMS
ppm
RMS
ppm/√kHr
ppm
ppm
ppm
LT1461DHS8
Load Regulation Sourcing (Note 6)
V
IN
= V
OUT
+ 2.5V
0
≤
I
OUT
≤
50mA
q
15
12
q
LT1461DHS8, 0
≤
I
OUT
≤
10mA
Dropout Voltage
V
IN
– V
OUT
, V
OUT
Error = 0.1%
I
OUT
= 0mA
I
OUT
= 1mA
I
OUT
= 10mA
I
OUT
= 50mA, I and C Grades Only
Short V
OUT
to GND
Logic High Input Voltage
Logic High Input Current, Pin 3 = 2.4V
Logic Low Input Voltage
Logic Low Input Current, Pin 3 = 0.8V
Supply Current
Shutdown Current
Output Voltage Noise (Note 7)
No Load
q
q
q
q
0.06
0.13
0.20
1.50
100
2.4
2
0.5
35
0.3
0.4
2.0
Output Current
Shutdown Pin
q
q
q
q
q
15
0.8
4
50
70
35
55
R
L
= 1k, Pin 3 = 0.8V
q
25
20
8
24
9.6
60
40
70
120
0.1Hz
≤
f
≤
10Hz
10Hz
≤
f
≤
1kHz
Long-Term Drift of Output Voltage, SO-8 Package (Note 8)
Thermal Hysteresis (Note 9)
See Applications Information
∆T
= 0°C to 70°C
∆T
= – 40°C to 85°C
∆T
= – 40°C to 125°C
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LT1461 is guaranteed functional over the operating
temperature range of – 40°C to 125°C.
Note 3:
If the part is stored outside of the specified temperature range, the
output may shift due to hysteresis.
Note 4:
ESD (Electrostatic Discharge) sensitive device. Extensive use of
ESD protection devices are used internal to the LT1461, however, high
electrostatic discharge can damage or degrade the device. Use proper ESD
handling precautions.
Note 5:
Temperature coefficient is calculated from the minimum and
maximum output voltage measured at T
MIN
, Room and T
MAX
as follows:
TC = (V
OMAX
– V
OMIN
)/(T
MAX
– T
MIN
)
Incremental slope is also measured at 25°C.
Note 6:
Load regulation is measured on a pulse basis from no load to the
specified load current. Output changes due to die temperature change
must be taken into account separately.
Note 7:
Peak-to-peak noise is measured with a single pole highpass filter
at 0.1Hz and a 2-pole lowpass filter at 10Hz. The unit is enclosed in a still-
air environment to eliminate thermocouple effects on the leads. The test
time is 10 sec. RMS noise is measured with a single pole highpass filter at
10Hz and a 2-pole lowpass filter at 1kHz. The resulting output is full-wave
rectified and then integrated for a fixed period, making the final reading an
average as opposed to RMS. A correction factor of 1.1 is used to convert
from average to RMS and a second correction of 0.88 is used to correct
for the nonideal bandpass of the filters.
Note 8:
Long-term drift typically has a logarithmic characteristic and
therefore, changes after 1000 hours tend to be much smaller than before
that time. Total drift in the second thousand hours is normally less than
one third that of the first thousand hours with a continuing trend toward
reduced drift with time. Long-term drift will also be affected by differential
stresses between the IC and the board material created during board
assembly.
See the Applications Information section.
Note 9:
Hysteresis in output voltage is created by package stress that
depends on whether the IC was previously at a higher or lower
temperature. Output voltage is always measured at 25°C, but the IC is
cycled hot or cold before successive measurements. Hysteresis is roughly
proportional to the square of the temperature change. Hysteresis is not
normally a problem for operational temperature excursions where the
instrument might be stored at high or low temperature. See Applications
Information.
3
LT1461-2.5
TYPICAL PERFORMANCE CHARACTERISTICS
Reference Voltage vs Temperature
2.5020
OUTPUT VOLTAGE CHANGE (mV)
2.5015
REFERENCE VOLTAGE (V)
TEMPCO –60°C TO 120°C
3 TYPICAL PARTS
2.5010
2.5005
2.5000
2.4995
2.4990
2.4985
2.4980
– 60 – 40 – 20
0 20 40 60 80 100 120
TEMPERATURE (°C)
1461 G01
3
125°C
25°C
2
LINE REGULATION (ppm/V)
Minimum Input/Output Voltage
Differential vs Load Current
10
INPUT/OUTPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
1
– 55°C
0.1
0.1
1
10
OUTPUT CURRENT (mA)
100
1461 G04
Current Limit vs Temperature
140
200
180
SHDN PIN CURRENT (µA)
120
CURRENT LIMIT (mA)
160
140
120
100
80
60
40
20
25°C
125°C
– 55°C
RIPPLE REJECTION RATIO (dB)
100
80
60
40
–50 –25
50
25
0
75
TEMPERATURE (°C)
4
U W
125°C
25°C
Load Regulation
4
Line Regulation vs Temperature
0
–1
–2
–3
–4
–5
–6
–7
SUPPLY
∆
= 15V
5V – 20V
0
20 40 60 80
TEMPERATURE (°C)
100 120
1461 G03
1
– 55°C
0
0.1
1
10
OUTPUT CURRENT (mA)
100
1461 G02
–8
–40 – 20
Supply Current vs Input Voltage
1000
50
Supply Current vs Temperature
V
IN
= 5V
40
I
S
I
S(SHDN)
30
100
125°C
– 55°C
25°C
20
10
10
0
5
10
15
20
INPUT VOLTAGE (V)
25
1461 G05
0
– 40 –20
0
20 40
60 80
TEMPERATURE (°C)
100 120
1461 G06
SHDN Pin Current
vs SHDN Input Voltage
100
90
80
70
60
50
40
30
20
10
Ripple Rejection Ratio
vs Frequency
0
100
125
0
15
10
5
SHDN PIN INPUT VOLTAGE (V)
20
1461 G08
0
0.01
0.1
1
10
FREQUENCY (kHz)
100
1000
1641 G01
1461 G07
LT1461-2.5
TYPICAL PERFORMANCE CHARACTERISTICS
Output Impedance vs Frequency
1000
C
OUT
= 2µF
OUTPUT IMPEDANCE (Ω)
VOLTAGE (V)
10
2
V
OUT
1
0
C
IN
= 1µF
C
L
= 2µF
R
L
=
∞
TIME (100µs/DIV)
1461 G11
VOLTAGE (V)
100
C
OUT
= 1µF
1
0.01
0.1
1
FREQUENCY (kHz)
Transient Response to 10mA
Load Step
I
OUT
0mA
10mA/DIV
5V
4V
V
OUT
50mV/DIV
V
OUT
50mV/DIV
C
L
= 2µF
1461 G13
C
IN
= 0.1µF
1461 G14
OUTPUT NOISE (20µV/DIV)
250
200
150
ppm
100
50
0
–50
0
200
400
600
800
1000
HOURS
1200
1400
1600
1800
2000
1461 G15
U W
10
1461 G10
Turn-On Time
20
10
0
V
IN
20
10
0
Turn-On Time
V
IN
2
V
OUT
1
0
C
IN
= 1µF
C
L
= 2µF
R
L
= 50Ω
TIME (100µs/DIV)
1461 G12
Line Transient Response
Output Noise 0.1Hz
≤
f
≤
10Hz
V
IN
TIME (2SEC/DIV)
1461 G18
Long-Term Drift (Number of Data Points Reduced at 650 Hours)*
LT1461S8-2.5
3 TYPICAL PARTS SOLDERED ONTO PCB
T
A
= 30°C
*SEE APPLICATIONS INFORMATION FOR DETAILED EXPLANATION OF LONG-TERM DRIFT
5
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