LTC6655
0.25ppm Noise, Low Drift
Precision Buffered
Reference Family
FeaTures
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DescripTion
The LTC
®
6655 is a complete family of precision bandgap
voltage references, offering exceptional noise and drift
performance. This low noise and drift is ideally suited for
the high resolution measurements required by instrumenta-
tion and test equipment. In addition, the LTC6655 is fully
specified over the temperature range of –40°C to 125°C,
ensuring its suitability for demanding automotive and
industrial applications. Advanced curvature compensation
allows this bandgap reference to achieve a drift of less than
2ppm/°C with a predictable temperature characteristic
and an output voltage accurate to ±0.025%, reducing or
eliminating the need for calibration.
The LTC6655 can be powered from as little as 500mV
above the output voltage to as much as 13.2V. Superior
load regulation with source and sink capability, coupled
with exceptional line rejection, ensures consistent per-
formance over a wide range of operating conditions. A
shutdown mode is provided for low power applications.
Available in a small MSOP package, the LTC6655 family
of references is an excellent choice for demanding preci-
sion applications.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
n
Low Noise: 0.25ppm
P-P
(0.1Hz to 10Hz)
625nV
P-P
for the LTC6655-2.5
Low Drift: 2ppm/°C Max
High Accuracy: ±0.025% Max
Fully Specified from –40°C to 125°C
100% Tested at –40°C, 25°C and 125°C
Load Regulation: <10ppm/mA
Sinks and Sources Current: ±5mA
Low Dropout: 500mV
Maximum Supply Voltage: 13.2V
Low Power Shutdown: <20µA Max
Available Output Voltages: 1.25V, 2.048V, 2.5V, 3V,
3.3V, 4.096V, 5V
Available in an 8-Lead MSOP Package
applicaTions
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Instrumentation and Test Equipment
High Resolution Data Acquisition Systems
Weigh Scales
Precision Battery Monitors
High Temperature Applications
Precision Regulators
Medical Equipment
High Output Current Precision Reference
Typical applicaTion
Low Frequency 0.1Hz to 10Hz Noise (LTC6655-2.5)
Basic Connection
LTC6655-2.5
3V < V
IN
≤ 13.2V
C
IN
0.1µF
V
IN
SHDN
GND
V
OUT_F
V
OUT_S
V
OUT
C
OUT
10µF
6655 TA01a
500nV/DIV
1s/DIV
6655 TA01b
6655fa
LTC6655
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
SHDN
V
IN
GND*
GND
1
2
3
4
8
7
6
5
GND*
V
OUT_F
V
OUT_S
GND*
Input Voltage
V
IN
to GND .......................................... –0.3V to 13.2V
SHDN
to GND ........................... –0.3V to (V
IN
+ 0.3V)
Output Voltage:
V
OUT_F
...................................... –0.3V to (V
IN
+ 0.3V)
V
OUT_S
..................................................... –0.3V to 6V
Output Short-Circuit Duration ...................... Indefinite
Operating Temperature Range (Note 2) . –40°C to 125°C
Storage Temperature Range (Note 2)..... –65°C to 150°C
Lead Temperature Range (Soldering, 10 sec)
(Note 3)................................................................. 300°C
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 300°C/W
*CONNECT PINS TO DEVICE GND (PIN 4)
orDer inForMaTion
LEAD FREE FINISH
LTC6655BHMS8-1.25#PBF
LTC6655CHMS8-1.25#PBF
LTC6655BHMS8-2.048#PBF
LTC6655CHMS8-2.048#PBF
LTC6655BHMS8-2.5#PBF
LTC6655CHMS8-2.5#PBF
LTC6655BHMS8-3#PBF
LTC6655CHMS8-3#PBF
LTC6655BHMS8-3.3#PBF
LTC6655CHMS8-3.3#PBF
LTC6655BHMS8-4.096#PBF
LTC6655CHMS8-4.096#PBF
LTC6655BHMS8-5#PBF
LTC6655CHMS8-5#PBF
TAPE AND REEL
LTC6655BHMS8-1.25#TRPBF
LTC6655CHMS8-1.25#TRPBF
LTC6655BHMS8-2.048#TRPBF
LTC6655CHMS8-2.048#TRPBF
LTC6655BHMS8-2.5#TRPBF
LTC6655CHMS8-2.5#TRPBF
LTC6655BHMS8-3#TRPBF
LTC6655CHMS8-3#TRPBF
LTC6655BHMS8-3.3#TRPBF
LTC6655CHMS8-3.3#TRPBF
LTC6655BHMS8-4.096#TRPBF
LTC6655CHMS8-4.096#TRPBF
LTC6655BHMS8-5#TRPBF
LTC6655CHMS8-5#TRPBF
PART MARKING
LTFDG
LTFDG
LTFDH
LTFDH
LTFCY
LTFCY
LTFDJ
LTFDJ
LTFDK
LTFDK
LTFDM
LTFDM
LTFDN
LTFDN
PACKAGE DESCRIPTION
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
SPECIFIED TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
6655fa
LTC6655
aVailable opTions
OUTPUT VOLTAGE
1.250
2.048
2.500
3.000
3.300
4.096
5.000
INITIAL ACCURACY
0.025%
0.05%
0.025%
0.05%
0.025%
0.05%
0.025%
0.05%
0.025%
0.05%
0.025%
0.05%
0.025%
0.05%
TEMPERATURE COEFFICIENT
2ppm/°C
5ppm/°C
2ppm/°C
5ppm/°C
2ppm/°C
5ppm/°C
2ppm/°C
5ppm/°C
2ppm/°C
5ppm/°C
2ppm/°C
5ppm/°C
2ppm/°C
5ppm/°C
PART NUMBER
†
LTC6655BHMS8-1.25
LTC6655CHMS8-1.25
LTC6655BHMS8-2.048
LTC6655CHMS8-2.048
LTC6655BHMS8-2.5
LTC6655CHMS8-2.5
LTC6655BHMS8-3.0
LTC6655CHMS8-3.0
LTC6655BHMS8-3.3
LTC6655CHMS8-3.3
LTC6655BHMS8-4.096
LTC6655CHMS8-4.096
LTC6655BHMS8-5
LTC6655CHMS8-5
†
See Order Information section for complete part number listing.
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= V
OUT
+ 0.5V, V
OUT_S
connected to V
OUT_F
, unless otherwise noted.
PARAMETER
Output Voltage
Output Voltage Temperature Coefficient
(Note 4)
Line Regulation
Load Regulation (Note 5)
CONDITIONS
LTC6655B
LTC6655C
LTC6655B
LTC6655C
V
OUT
+ 0.5V ≤ V
IN
≤ 13.2V,
SHDN
= V
IN
l
l
l
elecTrical characTerisTics
MIN
–0.025
–0.05
TYP
MAX
0.025
0.05
UNITS
%
%
ppm/°C
ppm/°C
ppm/V
ppm/V
ppm/mA
ppm/mA
ppm/mA
ppm/mA
V
V
V
mA
mA
1
2.5
5
3
2
5
25
40
15
30
13.2
13.2
13.2
I
SOURCE
= 5mA
l
I
SINK
= 5mA
l
10
Operating Voltage (Note 6)
LTC6655-1.25, LTC6655-2.048, LTC6655-2.5
I
SOURCE
= 5mA, V
OUT
Error ≤ 0.1%
LTC6655-3, LTC6655-3.3, LTC6655-4.096, LTC6655-5
I
SOURCE
= ±5mA, V
OUT
Error ≤ 0.1%
I
OUT
= 0mA, V
OUT
Error ≤ 0.1%
l
3
l
V
OUT
+ 0.5
l
V
OUT
+ 0.2
Output Short-Circuit Current
Shutdown Pin (SHDN)
Short V
OUT
to GND
Short V
OUT
to V
IN
Logic High Input Voltage
Logic High Input Current,
SHDN
= 2V
Logic Low Input Voltage
Logic Low Input Current,
SHDN
= 0.8V
l
l
l
l
20
20
2.0
12
0.8
15
5
l
l
V
µA
V
µA
mA
mA
µA
Supply Current
Shutdown Current
No Load
SHDN
Tied to GND
7
7.5
20
6655fa
LTC6655
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= V
OUT
+ 0.5V, V
OUT_S
connected to V
OUT_F
, unless otherwise noted.
PARAMETER
Output Voltage Noise (Note 7)
Turn-On Time
Long-Term Drift of Output Voltage (Note 8)
Hysteresis (Note 9)
∆T
= –0°C to 70°C
∆T
= –40°C to 85°C
∆T
= –40°C to 125°C
CONDITIONS
0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
0.1% Settling, C
OUT
= 2.7µF
MIN
TYP
0.25
0.67
400
60
30
35
60
MAX
UNITS
ppm
P-P
ppm
RMS
µs
ppm/√kHr
ppm
ppm
ppm
elecTrical characTerisTics
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Precision may be affected if the parts are stored outside of the
specified temperature range. Large temperature changes may cause
changes in device performance due to thermal hysteresis. For best
performance, extreme temperatures should be avoided whenever possible.
Note 3:
The stated temperature is typical for soldering of the leads during
manual rework. For detailed IR reflow recommendations, refer to the
Applications Information section.
Note 4:
Temperature coefficient is measured by dividing the maximum
change in output voltage by the specified temperature range.
Note 5:
Load regulation is measured on a pulse basis from no load to
the specified load current. Load current does not include the 2mA sense
current. Output changes due to die temperature change must be taken into
account separately.
Note 6:
Excludes load regulation errors. Minimum supply for the
LTC6655-1.25, LTC6655-2.048 and LTC6655-2.5 is set by internal circuitry
supply requirements, regardless of load condition. Minimum supply for
the LTC6655-3, LTC6655-3.3, LTC6655-4.096 and LTC6655-5 is specified
by load current.
Note 7:
Peak-to-peak noise is measured with a 2-pole highpass filter at
0.1Hz and 3-pole lowpass filter at 10Hz. The unit is enclosed in a still-air
environment to eliminate thermocouple effects on the leads, and the
test time is 10 seconds. Due to the statistical nature of noise, repeating
noise measurements will yield larger and smaller peak values in a given
measurement interval. By repeating the measurement for 1000 intervals,
each 10 seconds long, it is shown that there are time intervals during
which the noise is higher than in a typical single interval, as predicted by
statistical theory. In general, typical values are considered to be those for
which at least 50% of the units may be expected to perform similarly or
better. For the 1000 interval test, a typical unit will exhibit noise that is
less than the typical value listed in the Electrical Characteristics table in
more than 50% of its measurement intervals. See Application Note 124 for
noise testing details. RMS noise is measured with a spectrum analyzer in a
shielded environment.
Note 8:
Long-term stability 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 stability is also affected by differential
stresses between the IC and the board material created during board
assembly.
Note 9:
Hysteresis in output voltage is created by mechanical stress
that differs depending 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 to the hot or cold temperature limit before successive
measurements. Hysteresis is roughly proportional to the square of the
temperature change. For instruments that are stored at well controlled
temperatures (within 20 or 30 degrees of operational temperature),
hysteresis is usually not a significant error source.
6655fa
LTC6655
Typical perForMance characTerisTics
1.25V Low Frequency
0.1Hz to 10Hz Noise
1.2504
Characteristic curves are similar for most voltage options of the LTC6655. Curves from the LTC6655-1.25, LTC6655-2.5 and the
LTC6655-5 represent the range of performance across the entire family of references. Characteristic curves for other output voltages
fall between these curves and can be estimated based on their voltage output.
1.25V Output Voltage
Temperature Drift
3 TYPICAL UNITS
OUTPUT VOLTAGE CHANGE (ppm)
20
10
0
–10
–20
–30
–40
0.001
1.25V Load Regulation (Sourcing)
125°C
25°C
–40°C
200nV/
DIV
OUTPUT VOLTAGE (V)
6655 G01
1.2502
1.2500
1.2498
1s/DIV
1.2496
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
0.01
0.1
1
OUTPUT CURRENT (mA)
10
6655 G03
6655 G02
1.25V Load Regulation (Sinking)
200
OUTPUT VOLTAGE CHANGE (ppm)
160
125°C
25°C
–40°C
NOISE VOLTAGE (nV/√Hz)
40
35
30
25
20
15
10
5
0
0.001
0.01
0.1
1
OUTPUT CURRENT (mA)
10
6655 G04
1.25V Output Voltage Noise
Spectrum
1.25V Sinking Current with a
3.3µF Output Capacitor
I
OUT
5mA
0mA
120
80
40
V
OUT
10mV/DIV
0
0.01
2.7µF
10µF
100µF
0.1
1
10
FREQUENCY (kHz)
100
1000
6655 G05
C
OUT
= 3.3µF
200µs/DIV
6655 G06
1.25V Sourcing Current with a
3.3µF Output Capacitor
14
12
SUPPLY CURRENT (µA)
10
8
6
4
2
0
1.25V Shutdown Supply Current
vs Input Voltage
125°C
25°C
–40°C
NUMBER OF PARTS
60
50
40
30
20
10
1.25V V
OUT
Distribution
T
A
= 25°C
I
OUT
–5mA
0mA
V
OUT
10mV/DIV
C
OUT
= 3.3µF
200µs/DIV
6655 G07
0
2
8
6
10
4
INPUT VOLTAGE (V)
12
14
6655 G08
0
1.2495
1.2498
1.2500
V
OUT
(V)
1.2503
1.2505
6655 G09
6655fa
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