LT6657
1.5ppm/°C Drift, Low Noise,
Buffered Reference
FeaTures
n
DescripTion
The
LT
®
6657
is a precision voltage reference that combines
robust operating characteristics with extremely low drift
and low noise. With advanced curvature compensation,
this bandgap reference achieves 1.5ppm/°C drift with
predictable temperature behavior, and an initial voltage
accuracy of 0.1%. It also offers 0.5ppm
P-P
noise and very
low temperature cycling hysteresis.
The LT6657 is a low dropout reference that can be powered
from as little as 50mV above the output voltage, up to 40V.
The buffered output supports ±10mA of output drive with
low output impedance and precise load regulation. The
high sink current capability allows operation as a negative
voltage reference with the same precision as a positive
reference. This part is safe under reverse battery condi-
tions, and includes current protection when the output is
short-circuited and thermal shutdown for overload condi-
tions. A shutdown is included to allow power reduction
while enabling a quick turn-on.
The LT6657 is fully specified over the temperature range of
–40°C to 125°C. It is available in the 8-lead MSOP package.
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.
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Low Drift
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A Grade: 1.5ppm/°C Max
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B Grade: 3ppm/°C Max
Low Noise:
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0.5ppm
P-P
(0.1Hz to 10Hz)
n
0.8ppm
RMS
(10Hz to 1kHz)
Wide Supply Range to 40V
Sources and Sinks 10mA Min
Line Regulation: 0.2ppm/V
Load Regulation: 2µV/mA
Reverse Supply Protection
Reverse Output Protection
Low Power Shutdown: <4µA Max
1.5V Min Supply for 1.25V Option
Thermal Protection
Can Operate in Shunt Mode
Configurable as a Negative Reference
Available Output Voltage Options: 1.25V, 2.5V, 3V,
4.096V, 5V
MSOP-8 Package
applicaTions
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High Temperature Industrial
High Resolution Data Acquisition Systems
Instrumentation and Process Control
Automotive Control and Monitoring
Medical Equipment
Shunt and Negative Voltage References
OUTPUT VOLTAGE CHANGE (NORMALIZED) (PPM)
Typical applicaTion
Basic Connection
2
3
Output Voltage Temperature Drift
200
THREE TYPICAL PARTS
100
1ppm/°C BOX
0
(V
OUT
+ 50mV) < V
IN
< 40V
C
IN
0.1µF
IN
LT6657
SHDN
GND
4
OUT
6
V
OUT
C
OUT
1µF
6657 TA01a
–100
–200
–45
–20
30
80
5
55
TEMPERATURE (°C)
105
130
6657 TA01b
6657fd
For more information
www.linear.com/LT6657
1
LT6657
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
DNC
V
IN
SHDN
GND
1
2
3
4
8
7
6
5
DNC
DNC
V
OUT
DNC
Input Voltage V
IN
(to GND) .......................... –40V to 40V
Shutdown Voltage
SHDN
............................ –20V to 40V
Output Voltage V
OUT
..................................... –3V to 30V
Input-to-Output Differential Voltage (Note 2) ..........±40V
Output Short-Circuit Duration .......................... Indefinite
Operating Junction Temperature
Range ................................................ –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering 10 sec)
(Note 3) ............................................................ 300°C
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150°C,
θ
JA
= 273°C/W
DNC: CONNECTED INTERNALLY
DO NOT CONNECT EXTERNAL CIRCUITRY TO THESE PINS
orDer inForMaTion
TUBE
LT6657AHMS8-1.25#PBF
LT6657BHMS8-1.25#PBF
LT6657AHMS8-2.5#PBF
LT6657BHMS8-2.5#PBF
LT6657AHMS8-3#PBF
LT6657BHMS8-3#PBF
LT6657AHMS8-4.096#PBF
LT6657BHMS8-4.096#PBF
LT6657AHMS8-5#PBF
LT6657BHMS8-5#PBF
TAPE AND REEL
http://www.linear.com/product/LT6657#orderinfo
PART MARKING* PACKAGE DESCRIPTION
LTGYR
LTGYR
LTGKN
LTGKN
LTGYG
LTGYG
LTHCJ
LTHCJ
LTGYH
LTGYH
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
LT6657AHMS8-1.25#TRPBF
LT6657BHMS8-1.25#TRPBF
LT6657AHMS8-2.5#TRPBF
LT6657BHMS8-2.5#TRPBF
LT6657AHMS8-3#TRPBF
LT6657BHMS8-3#TRPBF
LT6657AHMS8-4.096#TRPBF
LT6657BHMS8-4.096#TRPBF
LT6657AHMS8-5#TRPBF
LT6657BHMS8-5#TRPBF
*Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges. Parts ending with PBF are RoHS and WEEE compliant.
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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
2
6657fd
For more information
www.linear.com/LT6657
LT6657
available opTions
OUTPUT VOLTAGE
1.25V
2.5V
3V
4.096V
5V
INITIAL ACCURACY
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
TEMPERATURE COEFFICIENT
1.5ppm/°C
3ppm/°C
1.5ppm/°C
3ppm/°C
1.5ppm/°C
3ppm/°C
1.5ppm/°C
3ppm/°C
1.5ppm/°C
3ppm/°C
ORDER PART NUMBER**
LT6657AHMS8-1.25
LT6657BHMS8-1.25
LT6657AHMS8-2.5
LT6657BHMS8-2.5
LT6657AHMS8-3
LT6657BHMS8-3
LT6657AHMS8-4.096
LT6657BHMS8-4.096
LT6657AHMS8-5
LT6657BHMS8-5
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
** See the 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. The test conditions are V
IN
= V
OUT
+ 0.5V, V
SHDN
= 1.6V, I
OUT
= 0,
C
IN
= 0.1µF, C
OUT
= 1µF. For LT6657-1.25 V
SHDN
= 1.45V, C
IN
= 1µF, C
OUT
= 2.7µF, unless otherwise noted.
PARAMETER
Output Voltage Accuracy
Output Voltage Temperature Coefficient
(Note 4)
Line Regulation (Note 5)
Load Regulation (Note 5)
LT6657A
LT6657B
V
OUT
+ 0.5V ≤ V
IN
≤ 40V
l
l
l
elecTrical characTerisTics
CONDITIONS
MIN
–0.1
TYP
0
0.5
1
0.2
2
MAX
0.1
1.5
3
2
4
6
10
8
15
15
UNITS
%
ppm/°C
ppm/°C
ppm/V
ppm/V
µV/mA
µV/mA
µV/mA
µV/mA
µV/mA
I
OUT
(Source) = 10mA
l
I
OUT
(Sink) = 10mA
l
3
l
Shunt Configuration All, Except LT6657-1.25
V
OUT
Is Shorted to V
IN
I
SHUNT
2.5 to 11mA
Minimum V
IN
– V
OUT
All, Except LT6657-1.25
V
IN
– V
OUT
,
ΔV
OUT
= 0.1%
I
OUT
= 0mA
3
20
l
50
70
100
140
450
500
–150
–50
200
250
200
250
450
500
200
250
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
I
OUT
(Source) = 1mA
l
65
330
l
I
OUT
(Source) = 10mA
I
OUT
(Sink) = 10mA
l
–230
120
l
LT6657-1.25V
V
IN
– V
OUT
,
ΔV
OUT
= 0.1%
I
OUT
= 0mA
I
OUT
(Source) = 1mA
l
120
330
l
I
OUT
(Source) = 10mA
I
OUT
(Sink) = 10mA
l
120
6657fd
For more information
www.linear.com/LT6657
3
LT6657
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. The test conditions are V
IN
= V
OUT
+ 0.5V, V
SHDN
= 1.6V, I
OUT
= 0,
C
IN
= 0.1µF, C
OUT
= 1µF. For LT6657-1.25 V
SHDN
= 1.45V, C
IN
= 1µF, C
OUT
= 2.7µF, unless otherwise noted.
PARAMETER
Shutdown Pin (SHDN) All, Except LT6657-1.25
CONDITIONS
Logic High Input Voltage
Logic High Input Current,
SHDN
= 1.6V
Logic Low Input Voltage
Logic Low Input Current,
SHDN
= 0.8V
LT6657-1.25V
Logic High Input Voltage
Logic High Input Current,
SHDN
= 1.45V
Logic Low Input Voltage
Logic Low Input Current,
SHDN
= 0.8V
Supply Current in Shutdown
Supply Current
Output Short-Circuit Current
Output Voltage Noise (Note 6)
Turn-On Time
Long-Term Drift of Output Voltage (Note 7)
Hysteresis (Note 8)
ΔT = 0°C to 50°C
ΔT = 0°C to 70°C
ΔT = –40°C to 85°C
ΔT = –40°C to 125°C
ΔT = –55°C to 125°C
SHDN
= 0.4V
SHDN
= 0.8V
No Load
l
l
l
l
l
l
l
l
l
l
l
elecTrical characTerisTics
MIN
1.6
TYP
0.7
0.2
MAX
2
0.8
1
2
0.8
1
4
20
1.8
2.3
UNITS
V
µV
V
µV
V
µV
V
µV
µA
µA
mA
mA
mA
mA
ppm
P-P
ppm
RMS
µsec
ppm/√kHr
ppm
ppm
ppm
ppm
ppm
1.45
0.5
0.05
0.01
2.0
1.2
15
16
0.5
0.8
180
30
20
24
30
35
40
Short V
OUT
to GND
Short V
OUT
to V
IN
0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
0.1% Settling, C
OUT
= 1µF
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:
With V
IN
at 40V, V
OUT
may not be pulled below 0V. The total V
IN
to
V
OUT
differential voltage must not exceed ±40V.
Note 3:
The stated temperature is typical for soldering of the leads during
manual rework. For detailed IR reflow recommendations, refer to the
Application information section.
Note 4:
Temperature coefficient is measured by dividing the maximum
change in output voltage by the specified temperature range.
Note 5:
Line and load regulation are measured on a pulse basis for
specified input voltage or load current ranges. Output voltage change due
to die temperature change must be taken into account separately.
Note 6:
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 7:
Long term stability typically has a logarithmic characteristic
and therefore change 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 of the first thousand hours with a continuing trend
toward reduced drift with time. Long-term stability will also be affected by
differential stresses between the IC and the board material created during
board assembly.
Note 8 :
Hysteresis in output voltage is created by mechanical stress that
depends on whether the IC was previously at a different temperature.
Output voltage is always measured at 25°C, but the IC is cycled 25°C to
cold to 25°C, or 25°C to hot to 25°C before successive measurements.
Hysteresis measures the maximum output change for the averages of
three hot or cold temperature cycles, preconditioned by one cold and one
hot cycles. For instruments that are stored at well controlled temperatures
(within 30 degrees of the operational temperature), hysteresis is usually
not a significant error source.
4
6657fd
For more information
www.linear.com/LT6657
LT6657
Typical perForMance characTerisTics
1.25V Output Voltage
Temperature Drift
1.2504
1.2502
OUTPUT VOLTAGE (V)
1.2500
1.2498
1.2496
1.2494
1.2492
–50
–25
–5 –4
–3
–2
–1 0
1 2
TIME (1s/DIV)
3
4
5
The test conditions are T
A
= 25°C,V
IN
= V
OUT
+ 0.5V,
V
SHDN
= 1.6V, I
OUT
= 0, C
IN
= 0.1µF, C
OUT
= 1µF. For LT6657-1.25 V
SHDN
= 1.45V, C
IN
= 1µF, C
OUT
= 2.7µF, unless otherwise noted.
1.25V Low Frequency 0.1Hz to
10Hz Noise
55
50
NOISE VOLTAGE (nV/√Hz)
45
40
35
30
0
0.01
C
OUT
= 2.7µF CER
C
OUT
= 5µF CER
C
OUT
= 47µF TANT
1.25V Output Voltage Noise
Spectrum
THREE TYPICAL PARTS
OUTPUT NOISE (250nV/DIV)
0
25 50 75 100
125
150
TEMPERATURE (°C)
6657 G01
0.1
6657 G02
1
10
FREQUENCY (kHz)
100
6657 G03
1.25V Integrated Noise
10Hz to 10kHz
100
C
OUT
= 2.7µF
2.0
1.25V Supply Current vs
Input Voltage
V
SHDN
= V
IN
1.2504
1.25V Line Regulation
MS8 PACKAGE PART SELF
HEATING IS INCLUDED
125°C
25°C
–40°C
INTEGRATED NOISE (µV
RMS
)
1.5
INPUT CURRENT (mA)
10
OUTPUT VOLTAGE (V)
40
1.2502
1.0
1.2500
1
0.5
125°C
25°C
–40°C
–55°C
30
0
1.2498
0
0.01
0.1
1
FREQUENCY (kHz)
10
6657 G04
–0.5
–40
–30 –20
–10
0
10 20
INPUT VOLTAGE (V)
1.2496
0
10
20
30
INPUT VOLTAGE (V)
40
6657 G06
6657 G05
1.25V Load Regulation (Sourcing)
30
OUTPUT VOLTAGE CHANGE (µV)
20
10
0
–10
–20
–30
0.1
MS8 PACKAGE PART SELF
HEATING IS INCLUDED
125°C
25°C
–40°C
–55°C
30
OUTPUT VOLTAGE CHANGE (µV)
20
10
0
–10
–20
1.25V Load Regulation (Sourcing)
MS8 PACKAGE PART SELF
HEATING IS INCLUDED
125°C
25°C
–40°C
–55°C
60
OUTPUT VOLTAGE CHANGE (µV)
50
40
30
20
1.25V Load Regulation (Sinking)
MS8 PACKAGE PART SELF
HEATING IS INCLUDED
125°C
25°C
–40°C
–55°C
V
IN
≥1.50V
10
0
0.1
V
IN
= 1.50V
1
OUTPUT CURRENT (mA)
10
6657 G07
–30
0.1
1
OUTPUT CURRENT (mA)
10
6657 G08
1
OUTPUT CURRENT (mA)
10
6657 G09
6657fd
For more information
www.linear.com/LT6657
5
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