LT1461
Micropower Precision
Low Dropout Series
Voltage Reference Family
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
Voltage Options: 2.5V, 3V, 3.3V, 4.096V and 5V
APPLICATIO S
s
s
s
s
A/D and D/A Converters
Precision Regulators
Handheld Instruments
Power Supplies
The LT
®
1461 is a family of low dropout micropower bandgap
references that combine very high accuracy and low drift with
low supply current and high output drive. These series
references use advanced curvature compensation techniques
to obtain low temperature coefficient and trimmed precision
thin-film resistors to achieve high output accuracy. The
LT1461 family draws only 35µA of supply current, making
them ideal for low power and portable applications, however
their high 50mA output drive makes them 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. The LT1461 is
available in 2.5V, 3V, 3.3V 4.096V and 5V options.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
Basic Connection
(V
OUT
+ 0.3V)
≤
V
IN
≤
20V
LT1461
C
IN
1µF
C
L
2µF
1461 TA01
LT1461-2.5 Load Regulation, P
DISS
= 200mW
V
OUT
I
OUT
0mA
20mA
V
OUT
LOAD REG
1mV/DIV
U
10ms/DIV
1461 TA02
U
U
1
LT1461
ABSOLUTE
AXI U
RATI GS
Input Voltage ........................................................... 20V
Output Short-Circuit Duration ......................... Indefinite
Operating Temperature Range
(Note 2) ........................................... – 40°C to 125°C
Storage Temperature Range (Note 3) ... – 65°C to 150°C
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
TOP VIEW
DNC* 1
V
IN
2
SHDN 3
GND 4
8
7
6
5
DNC*
DNC*
V
OUT
DNC*
S8 PACKAGE
8-LEAD PLASTIC SO
*DNC: DO NOT CONNECT
T
JMAX
= 150°C,
θ
JA
= 190°C/ W
(Note 3)
LT1461ACS8-2.5
LT1461BCS8-2.5
LT1461CCS8-2.5
LT1461AIS8-2.5
LT1461BIS8-2.5
LT1461CIS8-2.5
LT1461DHS8-2.5
LT1461ACS8-3
LT1461BCS8-3
LT1461CCS8-3
LT1461AIS8-3
LT1461BIS8-3
LT1461CIS8-3
LT1461DHS8-3
LT1461ACS8-3.3
LT1461BCS8-3.3
LT1461CCS8-3.3
LT1461AIS8-3.3
LT1461BIS8-3.3
LT1461CIS8-3.3
LT1461DHS8-3.3
LT1461ACS8-4
LT1461BCS8-4
LT1461CCS8-4
LT1461AIS8-4
LT1461BIS8-4
LT1461CIS8-4
LT1461DHS8-4
Consult factory for Military grade parts.
AVAILABLE OPTIO S
INITIAL
ACCURACY
0.04% Max
0.04% Max
0.06% Max
0.06% Max
0.08% Max
0.08% Max
0.15% Max
TEMPERATURE
COEFFICIENT
3ppm/°C Max
3ppm/°C Max
7ppm/°C Max
7ppm/°C Max
12ppm/°C Max
12ppm/°C Max
20ppm/°C Max
TEMPERATURE
RANGE
0°C to 70°C
– 40°C to 85°C
0°C to 70°C
– 40°C to 85°C
0°C to 70°C
– 40°C to 85°C
–40°C to 125°C
OUTPUT VOLTAGE
2.5V
LT1461ACS8-2.5
LT1461AIS8-2.5
LT1461BCS8-2.5
LT1461BIS8-2.5
LT1461CCS8-2.5
LT1461CIS8-2.5
LT1461DHS8-2.5
3.0V
LT1461ACS8-3
LT1461AIS8-3
LT1461BCS8-3
LT1461BIS8-3
LT1461CCS8-3
LT1461CIS8-3
LT1461DHS8-3
3.3V
LT1461ACS8-3.3
LT1461AIS8-3.3
LT1461BCS8-3.3
LT1461BIS8-3.3
LT1461CCS8-3.3
LT1461CIS8-3.3
LT1461DHS8-3.3
4.096V
LT1461ACS8-4
LT1461AIS8-4
LT1461BCS8-4
LT1461BIS8-4
LT1461CCS8-4
LT1461CIS8-4
LT1461DHS8-4
5.0V
LT1461ACS8-5
LT1461AIS8-5
LT1461BCS8-5
LT1461BIS8-5
LT1461CCS8-5
LT1461CIS8-5
LT1461DHS8-5
2
U
U
W
W W
U
U
W
(Note 1)
Specified Temperature Range
Commercial ............................................ 0°C to 70°C
Industrial ........................................... – 40°C to 85°C
High ................................................. – 40°C to 125°C
Lead Temperature (Soldering, 10 sec).................. 300°C
S8 PART MARKING
LT1461ACS8-5
LT1461BCS8-5
LT1461CCS8-5
LT1461AIS8-5
LT1461BIS8-5
LT1461CIS8-5
LT1461DHS8-5
461A25
461B25
461C25
61AI25
61BI25
61CI25
61DH25
1461A3
1461B3
1461C3
461AI3
461BI3
461CI3
461DH3
461A33
461B33
461C33
61AI33
61BI33
61CI33
61DH33
1461A4
1461B4
1461C4
461AI4
461BI4
461CI4
461DH4
1461A5
1461B5
1461C5
461AI5
461BI5
461CI5
461DH5
LT1461
ELECTRICAL CHARACTERISTICS
PARAMETER
Output Voltage (Note 4)
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.
CONDITIONS
LT1461ACS8/LT1461AIS8
LT1461BCS8/LT1461BIS8
LT1461CCS8/LT1461CIS8
LT1461DHS8
LT1461ACS8/LT1461AIS8
LT1461BCS8/LT1461BIS8
LT1461CCS8/LT1461CIS8
LT1461DHS8
(V
OUT
+ 0.5V)
≤
V
IN
≤
20V
q
q
q
q
q
MIN
– 0.04
– 0.06
– 0.08
– 0.15
TYP
MAX
0.04
0.06
0.08
0.15
UNITS
%
%
%
%
ppm/°C
ppm/°C
ppm/°C
ppm/°C
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
ppm
P-P
ppm
RMS
ppm/√kHr
ppm
ppm
ppm
Output Voltage Temperature Coefficient (Note 5)
1
3
5
7
2
3
7
12
20
8
12
50
30
40
50
Line Regulation
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)
Long-Term Drift of Output Voltage, SO-8 Package (Note 8)
Thermal Hysteresis (Note 9)
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
q
25
8
9.6
60
40
75
120
0.1Hz
≤
f
≤
10Hz
10Hz
≤
f
≤
1kHz
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, or
the junction temperature exceeds 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 seconds. 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.
3
LT1461
ELECTRICAL CHARACTERISTICS
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 section.
TYPICAL PERFOR A CE CHARACTERISTICS
2.5V Reference Voltage
vs Temperature
2.5020
OUTPUT VOLTAGE CHANGE (ppm)
2.5015
REFERENCE VOLTAGE (V)
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
Characteristic curves are similar for most LT1461s.
Curves from the LT1461-2.5 and the LT1461-5 represent the extremes of the voltage options. Characteristic curves for other output
voltages fall between these curves and can be estimated based on their output.
2.5V Load Regulation
1600
V
IN
= 7.5V
LINE REGULATION (ppm/V)
TEMPCO –60°C TO 120°C
3 TYPICAL PARTS
2.5V Minimum Input/Output
Voltage Differential vs Load Current
10
1000
RIPPLE REJECTION RATIO (dB)
INPUT/OUTPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
1
– 55°C
0.1
0.1
1
10
OUTPUT CURRENT (mA)
100
1461 G04
4
U W
125°C
25°C
2.5V Line Regulation
vs Temperature
0
–1
1200
125°C
25°C
800
–2
–3
–4
–5
–6
–7
SUPPLY
∆
= 15V
5V – 20V
0
20 40 60 80
TEMPERATURE (°C)
100 120
1461 G03
400
– 55°C
0
0.1
1
10
OUTPUT CURRENT (mA)
100
1461 G02
–8
–40 – 20
2.5V Supply Current
vs Input Voltage
100
90
80
70
60
50
40
30
20
10
10
0
5
10
15
20
INPUT VOLTAGE (V)
25
1461 G05
2.5V Ripple Rejection Ratio
vs Frequency
100
125°C
– 55°C
25°C
0
0.01
0.1
1
10
FREQUENCY (kHz)
100
1000
1641 G06
LT1461
Characteristic curves are similar for most LT1461s.
Curves from the LT1461-2.5 and the LT1461-5 represent the extremes of the voltage options. Characteristic curves for other output
voltages fall between these curves and can be estimated based on their output.
2.5V Output Impedance
vs Frequency
1000
C
OUT
= 2µF
TYPICAL PERFOR A CE CHARACTERISTICS
OUTPUT IMPEDANCE (Ω)
VOLTAGE (V)
10
2
V
OUT
1
0
C
IN
= 1µF
C
L
= 2µF
R
L
=
∞
TIME (100µs/DIV)
1461 G08
VOLTAGE (V)
100
C
OUT
= 1µF
1
0.01
0.1
1
FREQUENCY (kHz)
2.5V 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 G10
C
IN
= 0.1µF
1461 G11
OUTPUT NOISE (10µV/DIV)
U W
10
1461 G07
2.5V Turn-On Time
20
10
0
V
IN
20
10
0
2.5V Turn-On Time
V
IN
2
V
OUT
1
0
C
IN
= 1µF
C
L
= 2µF
R
L
= 50Ω
TIME (100µs/DIV)
1461 G09
2.5V Line Transient Response
2.5V Output Noise
0.1Hz
≤
f
≤
10Hz
V
IN
TIME (2SEC/DIV)
1461 G12
5
