LINER LT6656

LT6654
SOT-23 Precision Wide
Supply High Output Drive
Low Noise Reference
Description
Features
Low Drift:
A Grade: 10ppm/°C Max
B Grade: 20ppm/°C Max
n High Accuracy:
A Grade: ±0.05% Max
B Grade: ±0.10% Max
n Low Noise: 1.6ppm
P-P (0.1Hz to 10Hz)
n Wide Supply Range to 36V
n Low Thermal Hysteresis
n Line Regulation (Up to 36V): 5ppm/V Max
n Low Dropout Voltage: 100mV Max
n Sinks and Sources ±10mA
n Load Regulation at 10mA: 8ppm/mA Max
n Easily Configured for Negative Voltage Output
n Fully Specified from –55°C to 125°C
n Available Output Voltage Options: 1.25V, 2.048V, 2.5V,
3V, 3.3V, 4.096V, 5V
n Low Profile (1mm) ThinSOT™ Package
n
n
n
n
n
n
The LT6654 was designed with advanced manufacturing techniques and curvature compensation to provide
10ppm/°C temperature drift and 0.05% initial accuracy.
Low thermal hysteresis ensures high accuracy and
1.6ppmP-P noise minimizes measurement uncertainty.
Since the LT6654 can also sink current, it can operate
as a low power negative voltage reference with the same
precision as a positive reference.
The LT6654 is offered in a 6-lead SOT-23 package.
Applications
n
The LT®6654 is a family of small precision voltage references that offers high accuracy, low noise, low drift,
low dropout and low power. The LT6654 operates from
voltages up to 36V and is fully specified from –55°C to
125°C. A buffered output ensures ±10mA of output drive
with low output impedance and precise load regulation.
These features, in combination, make the LT6654 ideal
for portable equipment, industrial sensing and control,
and automotive applications.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
Automotive Control and Monitoring
High Temperature Industrial
High Resolution Data Acquisition Systems
Instrumentation and Process Control
Precision Regulators
Medical Equipment
Typical Application
Output Voltage Temperature Drift
0.10
(VOUT + 0.5V) < VIN < 36V
4
CIN
0.1µF
6
LT6654
1
2
VOUT
CL
1µF
6654 TA01a
VOUT ACCURACY (%)
Basic Connection
3 TYPICAL PARTS
LT6654-2.5
0.05
0.00
–0.05
–0.10
–60 –40 –20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
6654 TA01b
6654fb
1
LT6654
Absolute Maximum Ratings
Pin Configuration
(Note 1)
Input Voltage VIN to GND............................ –0.3V to 38V
Output Voltage VOUT..........................–0.3V to VIN + 0.3V
Output Short-Circuit Duration .......................... Indefinite
Specified Temperature Range
H-Grade.............................................. –40°C to 125°C
MP-Grade........................................... –55°C to 125°C
Operating Temperature Range................ –55°C to 125°C
Storage Temperature Range (Note 2)...... –65°C to 150°C
Lead Temperature (Soldering, 10 sec.)
(Note 9).................................................................. 300°C
TOP VIEW
GND* 1
6 VOUT
GND 2
5 DNC
DNC 3
4 VIN
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
TJMAX = 150°C, θJA = 192°C/W
DNC: DO NOT CONNECT
*CONNECT PIN TO DEVICE GND (PIN 2)
order information
Lead Free Finish
TAPE AND REEL (MINI)
TAPE AND REEL
PART MARKING* PACKAGE DESCRIPTION
LT6654AHS6-1.25#TRMPBF
LT6654AHS6-1.25#TRPBF
LTFVD
6-Lead Plastic TSOT-23
LT6654BHS6-1.25#TRMPBF
LT6654BHS6-1.25#TRPBF
LTFVD
6-Lead Plastic TSOT-23
LT6654AMPS6-1.25#TRMPBF
LT6654AMPS6-1.25#TRPBF
LTFVD
6-Lead Plastic TSOT-23
LT6654BMPS6-1.25#TRMPBF
LT6654BMPS6-1.25#TRPBF
LTFVD
6-Lead Plastic TSOT-23
LT6654AHS6-2.048#TRMPBF
LT6654AHS6-2.048#TRPBF
LTFVF
6-Lead Plastic TSOT-23
LT6654BHS6-2.048#TRMPBF
LT6654BHS6-2.048#TRPBF
LTFVF
6-Lead Plastic TSOT-23
LT6654AMPS6-2.048#TRMPBF LT6654AMPS6-2.048#TRPBF LTFVF
6-Lead Plastic TSOT-23
LT6654BMPS6-2.048#TRMPBF LT6654BMPS6-2.048#TRPBF LTFVF
6-Lead Plastic TSOT-23
LT6654AHS6-2.5#TRMPBF
LT6654AHS6-2.5#TRPBF
LTFJY
6-Lead Plastic TSOT-23
LT6654BHS6-2.5#TRMPBF
LT6654BHS6-2.5#TRPBF
LTFJY
6-Lead Plastic TSOT-23
LT6654AMPS6-2.5#TRMPBF
LT6654AMPS6-2.5#TRPBF
LTFJY
6-Lead Plastic TSOT-23
LT6654BMPS6-2.5#TRMPBF
LT6654BMPS6-2.5#TRPBF
LTFJY
6-Lead Plastic TSOT-23
LT6654AHS6-3#TRMPBF
LT6654AHS6-3#TRPBF
LTFVG
6-Lead Plastic TSOT-23
LT6654BHS6-3#TRMPBF
LT6654BHS6-3#TRPBF
LTFVG
6-Lead Plastic TSOT-23
LT6654AMPS6-3#TRMPBF
LT6654AMPS6-3#TRPBF
LTFVG
6-Lead Plastic TSOT-23
LT6654BMPS6-3#TRMPBF
LT6654BMPS6-3#TRPBF
LTFVG
6-Lead Plastic TSOT-23
LT6654AHS6-3.3#TRMPBF
LT6654AHS6-3.3#TRPBF
LTFVH
6-Lead Plastic TSOT-23
LT6654BHS6-3.3#TRMPBF
LT6654BHS6-3.3#TRPBF
LTFVH
6-Lead Plastic TSOT-23
LT6654AMPS6-3.3#TRMPBF
LT6654AMPS6-3.3#TRPBF
LTFVH
6-Lead Plastic TSOT-23
LT6654BMPS6-3.3#TRMPBF
LT6654BMPS6-3.3#TRPBF
LTFVH
6-Lead Plastic TSOT-23
LT6654AHS6-4.096#TRMPBF
LT6654AHS6-4.096#TRPBF
LTFVJ
6-Lead Plastic TSOT-23
LT6654BHS6-4.096#TRMPBF
LT6654BHS6-4.096#TRPBF
LTFVJ
6-Lead Plastic TSOT-23
LT6654AMPS6-4.096#TRMPBF LT6654AMPS6-4.096#TRPBF LTFVJ
6-Lead Plastic TSOT-23
LT6654BMPS6-4.096#TRMPBF LT6654BMPS6-4.096#TRPBF LTFVJ
6-Lead Plastic TSOT-23
LT6654AHS6-5#TRMPBF
LT6654AHS6-5#TRPBF
LTFVK
6-Lead Plastic TSOT-23
LT6654BHS6-5#TRMPBF
LT6654BHS6-5#TRPBF
LTFVK
6-Lead Plastic TSOT-23
LT6654AMPS6-5#TRMPBF
LT6654AMPS6-5#TRPBF
LTFVK
6-Lead Plastic TSOT-23
LT6654BMPS6-5#TRMPBF
LT6654BMPS6-5#TRPBF
LTFVK
6-Lead Plastic TSOT-23
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on 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/
2
SPECIFIED TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
6654fb
LT6654
Available Options
OUTPUT VOLTAGE
1.25V
INITIAL ACCURACY
TEMPERATURE COEFFICIENT
0.05%
10ppm/°C
0.1%
20ppm/°C
0.05%
10ppm/°C
0.1%
20ppm/°C
2.048V
0.05%
10ppm/°C
0.1%
20ppm/°C
0.05%
10ppm/°C
0.1%
20ppm/°C
2.5V
0.05%
10ppm/°C
0.1%
20ppm/°C
0.05%
10ppm/°C
0.1%
20ppm/°C
3V
0.05%
10ppm/°C
0.1%
20ppm/°C
0.05%
10ppm/°C
0.1%
20ppm/°C
3.3V
0.05%
10ppm/°C
0.1%
20ppm/°C
0.05%
10ppm/°C
0.1%
20ppm/°C
4.096V
0.05%
10ppm/°C
0.1%
20ppm/°C
0.05%
10ppm/°C
0.1%
20ppm/°C
5V
0.05%
10ppm/°C
0.1%
20ppm/°C
0.05%
10ppm/°C
0.1%
20ppm/°C
** See the Order Information section for complete part number listing.
ORDER PART NUMBER**
LT6654AHS6-1.25
LT6654BHS6-1.25
LT6654AMPS6-1.25
LT6654BMPS6-1.25
LT6654AHS6-2.048
LT6654BHS6-2.048
LT6654AMPS6-2.048
LT6654BMPS6-2.048
LT6654AHS6-2.5
LT6654BHS6-2.5
LT6654AMPS6-2.5
LT6654BMPS6-2.5
LT6654AHS6-3
LT6654BHS6-3
LT6654AMPS6-3
LT6654BMPS6-3
LT6654AHS6-3.3
LT6654BHS6-3.3
LT6654AMPS6-3.3
LT6654BMPS6-3.3
LT6654AHS6-4.096
LT6654BHS6-4.096
LT6654AMPS6-4.096
LT6654BMPS6-4.096
LT6654AHS6-5
LT6654BHS6-5
LT6654AMPS6-5
LT6654BMPS6-5
SPECIFIED TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
–40°C to 125°C
–40°C to 125°C
–55°C to 125°C
–55°C to 125°C
Electrical Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, CL = 1µF and VIN = VOUT + 0.5V, unless otherwise noted.
For LT6654-1.25, VIN = 2.4V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
Output Voltage Accuracy
LT6654A
LT6654B
LT6654AH
LT6654BH
LT6654AMP
LT6654BMP
l
l
l
l
–0.05
–0.10
–0.215
–0.43
–0.23
–0.46
Output Voltage Temperature Coefficient (Note 3)
LT6654A
LT6654B
l
l
Line Regulation
VOUT + 0.5V ≤ VIN ≤ 36V
LT6654-2.048, LT6654-2.5, LT6654-3,
LT6654-3.3, LT6654-4.096, LT6654-5
l
2.4V ≤ VIN ≤ 36V
LT6654-1.25
l
Load Regulation (Note 4)
IOUT(SOURCE) = 10mA
LT6654-2.048, LT6654-2.5, LT6654-3,
LT6654-3.3, LT6654-4.096, LT6654-5
LT6654-1.25
TYP
UNITS
0.05
0.10
0.215
0.43
0.23
0.46
%
%
%
%
%
%
3
10
10
20
ppm/°C
ppm/°C
1.2
5
10
ppm/V
ppm/V
1.2
5
10
ppm/V
ppm/V
3
8
15
15
20
ppm/mA
ppm/mA
ppm/mA
ppm/mA
l
6
l
MAX
6654fb
3
LT6654
Electrical Characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, CL = 1µF and VIN = VOUT + 0.5V, unless otherwise noted.
For LT6654-1.25, VIN = 2.4V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
Load Regulation (Note 4)
IOUT(SINK) = 10mA
LT6654-2.048, LT6654-2.5, LT6654-3,
LT6654-3.3, LT6654-4.096, LT6654-5
LT6654-1.25
TYP
MAX
9
20
30
25
30
ppm/mA
ppm/mA
ppm/mA
ppm/mA
l
100
120
mV
mV
l
l
450
50
mV
mV
1.6
1.8
2.4
V
V
V
600
µA
µA
l
15
l
Dropout Voltage (Note 5)
Minimum Input Voltage
VIN – VOUT , ∆VOUT = 0.1%
IOUT = 0mA
LT6654-2.048, LT6654-2.5, LT6654-3,
LT6654-3.3, LT6654-4.096, LT6654-5
IOUT(SOURCE) = 10mA
IOUT(SINK) = –10mA
LT6654-1.25, ∆VOUT = 0.1%, IOUT = 0mA
LT6654-1.25, ∆VOUT = 0.1%, IOUT = ±10mA
Supply Current
55
1.5
l
l
No Load
350
l
UNITS
Output Short-Circuit Current
Short VOUT to GND
Short VOUT to VIN
40
30
mA
mA
Output Voltage Noise (Note 6)
0.1Hz ≤ f ≤ 10Hz
LT6654-1.25
LT6654-2.048
LT6654-2.5
LT6654-3
LT6654-3.3
LT6654-4.096
LT6654-5
10Hz ≤ f ≤ 1kHz
0.8
1.0
1.5
1.6
1.7
2.0
2.2
2.0
ppmP-P
ppmP-P
ppmP-P
ppmP-P
ppmP-P
ppmP-P
ppmP-P
ppmRMS
Turn-On Time
0.1% Settling, CLOAD = 1µF
150
µs
60
ppm/√kHr
30
40
90
100
ppm
ppm
ppm
ppm
Long-Term Drift of Output Voltage (Note 7)
Hysteresis (Note 8)
∆T = 0°C to 70°C
∆T = –40°C to 85°C
∆T = –40°C to 125°C
∆T = –55°C to 125°C
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: If the parts are stored outside of the specified temperature range,
the output may shift due to hysteresis.
Note 3: Temperature coefficient is measured by dividing the maximum
change in output voltage by the specified temperature range.
Note 4: 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 5: Excludes load regulation errors.
Note 6: Peak-to-peak noise is measured with a 1-pole highpass filter at
0.1Hz and 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 on a spectrum analyzer in
a shielded environment where the intrinsic noise of the instrument is
removed to determine the actual noise of the device.
Note 7: 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 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 package 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 measures the maximum output change for the
averages of three hot or cold temperature cycles. For instruments that
are stored at well controlled temperatures (within 20 or 30 degrees of
operational temperature), it’s usually not a dominant error source.
Note 9: The stated temperature is typical for soldering of the leads during
manual rework. For detailed IR reflow recommendations, refer to the
Applications Information section.
6654fb
4
LT6654
Typical Performance Characteristics
The characteristic curves are similar across the
LT6654 family. Curves from the LT6654-1.25, LT6654-2.5 and the LT6654-5 represent the full range of typical performance of all
voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
1.25V Output Voltage
Temperature Drift
1.2520
1.25V Output Impedance
vs Frequency
1.25V Turn-On Characteristics
100
THREE TYPICAL PARTS
1.2510
OUTPUT IMPEDANCE (Ω)
REFERENCE VOLTAGE (V)
1.2515
VIN
1V/DIV
1.2505
GND
1.2500
1.2495
VOUT
0.5V/DIV
1.2490
GND
1.2485
–60 –40 –20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
CLOAD = 1µF
CL = 1µF
1
CL = 10µF
0.1
0.01
0.1
6654 G02
20µs/DIV
10
1
1000
10
100
FREQUENCY (kHz)
6654 G03
6654 G01
1.25V Load Regulation (Sinking)
200
20
180
–55°C
10
–40°C
0
–10
125°C
–20
25°C
–30
–40
125°C
160
140
120
100
25°C
80
60
40
–40°C
20
–50
0.1
–55°C
0
0.1
10
1
OUTPUT CURRENT (mA)
1.25V Output Noise 0.1Hz to 10Hz
OUTPUT NOISE (1µV/DIV)
30
OUTPUT VOLTAGE CHANGE (ppm)
OUTPUT VOLTAGE CHANGE (ppm)
1.25V Load Regulation (Sourcing)
6654 G04
0
10
1
OUTPUT CURRENT (mA)
1
2
3
4 5 6 7
TIME (1s/DIV)
1.25V Minimum Input Voltage
(Sinking)
10
9
10
6654 G06
6654 G05
1.25V Minimum Input Voltage
(Sourcing)
8
1.2V Output Voltage Noise
Spectrum
10
400
350
25°C
–40°C
1
–55°C
125°C
NOISE VOLTAGE (nV√Hz)
125°C
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
25°C
–55°C
1
–40°C
300
250
200
150
IO = 0µA
100
IO = 5mA
50
0.1
1
1.2 1.4 1.6 1.8
2
2.2
MINIMUM INPUT VOLTAGE (V)
2.4
6654 G07
0.1
1
1.1
1.2 1.3 1.4 1.5 1.6 1.7
MINIMUM INPUT VOLTAGE (V)
1.8
6654 G08
0
0.01
0.1
1
10
FREQUENCY (kHz)
100
6654 G09
6654fb
5
LT6654
Typical Performance Characteristics
The characteristic curves are similar across the
LT6654 family. Curves from the LT6654-1.25, LT6654-2.5 and the LT6654-5 represent the full range of typical performance of all
voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
2.5V Output Voltage
Temperature Drift
THREE TYPICAL PARTS
2.5050
INPUT CURRENT (µA)
2.501
2.500
2.499
2.5040
–40°C
500
OUTPUT VOLTAGE (V)
2.5V Line Regulation
600
–55°C
400
2.5030
OUTPUT VOLTAGE (V)
2.502
2.5V Supply Current
vs Input Voltage
25°C
300
125°C
200
2.5020
2.5010
25°C
2.5000
2.4990
125°C
2.4980
–55°C
2.4970
100
2.4960
2.498
–60
–20
20
60
100
TEMPERATURE (°C)
0
140
0
5
10
15 20 25 30
INPUT VOLTAGE (V)
35
6654 G10
2.5V Load Regulation (Sourcing)
0
5
10
15 20 25 30
INPUT VOLTAGE (V)
40
35
6654 G12
2.5V Load Regulation (Sinking)
2.5V Output Noise 0.1Hz to 10Hz
180
–40°C
–10
125°C
25°C
–20
–30
–40
0.1
1
OUTPUT CURRENT (mA)
160
140
OUTPUT NOISE (1µV/DIV)
–55°C
0
OUTPUT VOLTAGE CHANGE (ppm)
120
100
125°C
80
25°C
60
40
–40°C
20
0
0.1
10
–55°C
10
1
OUTPUT CURRENT (mA)
6654 G14
6654 G13
2.5V Minimum VIN to VOUT
Differential (Sourcing)
2.5V Minimum VIN to VOUT
Differential (Sinking)
10
2.5V Output Voltage Noise
Spectrum
10
–55°C
400
25°C
350
OUTPUT CURRENT (mA)
–40°C
125°C
1
6654 G15
TIME (1s/DIV)
–55°C
NOISE VOLTAGE (nV√Hz)
OUTPUT VOLTAGE CHANGE (ppm)
2.4950
6654 G11
10
OUTPUT CURRENT (mA)
40
–40°C
–40°C
125°C
25°C
1
300
250
IO = 0µA
200
150
IO = 5mA
100
50
0.1
0
50
100 150 200 250 300 350 400
INPUT-OUTPUT VOLTAGE (mV)
6654 G16
0.1
50
–300 –250 –200 –150 –100 –50 0
INPUT-OUTPUT VOLTAGE (mV)
100
6654 G17
0
0.01
0.1
1
10
FREQUENCY (kHz)
100
6654 G18
6654fb
6
LT6654
Typical Performance Characteristics
The characteristic curves are similar across the
LT6654 family. Curves from the LT6654-1.25, LT6654-2.5 and the LT6654-5 represent the full range of typical performance of all
voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
2.5V Integrated Noise
10Hz to 10kHz
2.5V Power Supply Rejection
Ratio vs Frequency
–20
10
1
0.1
0.01
–30
–40
CL = 1µF
–50
–60
–70
CL = 10µF
–80
10
CL = 1µF
1
1
1000
10
100
FREQUENCY (kHz)
6654 G19
0.1
1
1000
10
100
FREQUENCY (kHz)
6654 G20
2.5V Turn-On Characteristics
6654 G21
2.5V Load Transient Response
(Sourcing)
2.5V Line Transient Response
VIN
0.5V/DIV
3V/DC
VIN
1V/DIV
CL = 10µF
–90
–100
0.1
10
0.1
1
FREQUENCY (kHz)
100
OUTPUT IMPEDANCE (Ω)
POWER SUPPLY REJECTION RATIO (dB)
INTEGRATED NOISE (µVRMS)
100
2.5V Output Impedance
vs Frequency
IOUT
0mA
5mA
GND
VOUT
2mV/DIV/AC
2.5V/DC
VOUT
1V/DIV
VOUT
20mV/DIV/AC
2.5V/DC
GND
CLOAD = 1µF
20µs/DIV
6654 G22
CLOAD = 1µF
2.5V Hysteresis Plot for –40°C
and 125°C
48
44
150
OUTPUT VOLTAGE CHANGE (ppm)
NUMBER OF UNITS
36
32
28
24
20
16
12
8
50µs/DIV
6654 G24
2.5V Load Transient Response
(Sinking)
TA = 35°C
120
IOUT
5mA
90
60
0mA
30
0
–30
VOUT
20mV/DIV/AC
2.5V/DC
–60
–90
4
–120
0
–150 –125 –100 –75 –50 –25 0 25 50 75 100 125 150
DISTRIBUTION (ppm)
–150
6654 G25
CLOAD = 1µF
2.5V Long Term Drift
MAX AVG HOT CYCLE MAX AVG COLD CYCLE
25°C TO 125°C TO 25°C 25°C TO –40°C TO 25°C
40
6654 G23
50µs/DIV
0
400
800
1200
TIME (HOURS)
1600
2000
CLOAD = 1µF
50µs/DIV
6654 G27
6654 G26
6654fb
7
LT6654
Typical Performance Characteristics
The characteristic curves are similar across the
LT6654 family. Curves from the LT6654-1.25, LT6654-2.5 and the LT6654-5 represent the full range of typical performance of all
voltage options. Characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
5V Output Voltage Temperature
Drift
5.003
100
THREE TYPICAL PARTS
5.002
5.001
5.000
OUTPUT IMPEDANCE (Ω)
REFERENCE VOLTAGE (V)
5V Output Impedance
vs Frequency
5V Turn-On Characteristics
VIN
2V/DIV
4.999
GND
4.998
4.997
4.996
VOUT
2V/DIV
4.995
10
CL = 1µF
1
CL = 10µF
0.1
GND
4.994
4.993
–60 –40 –20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
0.01
0.1
6654 G29
50µs/DIV
CLOAD = 1µF
1
1000
10
100
FREQUENCY (kHz)
6654 G28
6654 G30
5V Load Regulation (Sourcing)
5V Load Regulation (Sinking)
200
30
20
–55°C
–40°C
10
125°C
0
25°C
–10
180
OUTPUT NOISE (4µV/DIV)
40
160
140
120
–55°C
–40°C
100
80
125°C
60
25°C
40
20
–20
0.1
1
OUTPUT CURRENT (mA)
0
0.1
10
0
10
1
OUTPUT CURRENT (mA)
6654 G31
2
3
4 5 6 7
TIME (1s/DIV)
8
9
10
6654 G33
5V Minimum VIN to VOUT
Differential (Sinking)
10
5V Output Voltage Noise
Spectrum
10
600
25°C
550
OUTPUT CURRENT (mA)
–40°C
125°C
1
500
–55°C
NOISE VOLTAGE (nV√Hz)
–55°C
1
6654 G32
5V Minimum VIN to VOUT
Differential (Sourcing)
OUTPUT CURRENT (mA)
5V Output Noise 0.1Hz to 10Hz
220
OUTPUT VOLTAGE CHANGE (ppm)
OUTPUT VOLTAGE CHANGE (ppm)
50
25°C
125°C
–40°C
1
IO = 0µA
450
400
350
300
250
IO = 5mA
200
150
100
50
0.1
0
50
100 150 200 250 300 350 400
INPUT-OUTPUT VOLTAGE (mV)
6654 G34
0.1
–300 –250 –200 –150 –100 –50 0
50
INPUT-OUTPUT VOLTAGE (mV)
100
6654 G35
0
0.01
0.1
1
10
FREQUENCY (kHz)
100
6654 G36
6654fb
8
LT6654
Pin Functions
GND (Pin 1): Internal Function. This pin must be tied to
ground, near Pin 2.
DNC (Pin 5): Do Not Connect. Keep leakage current from
this pin to VIN or GND to a minimum.
GND (Pin 2): Primary Device Ground.
VOUT (Pin 6): Output Voltage. An output capacitor of 1µF
minimum is required for stable operation.
DNC (Pin 3): Do Not Connect. Keep leakage current from
this pin to VIN or GND to a minimum.
VIN (Pin 4): Power Supply. Bypass VIN with a 0.1µF
capacitor to ground.
Block Diagram
4
3
5
2
VIN
DNC
DNC
GND
+
BANDGAP
VOUT
6
–
GND
1
6654 BD
6654fb
9
LT6654
Applications Information
Bypass and Load Capacitors
The LT6654 voltage references should have an input bypass capacitor of 0.1µF or larger, however the bypassing
on other components nearby is sufficient. In high voltage
applications, VIN > 30V, an output short-circuit to ground
can create an input voltage transient that could exceed the
maximum input voltage rating. To prevent this worst-case
condition, an RC input line filter of 10µs (i.e. 10Ω and 1µF)
is recommended. These references also require an output
capacitor for stability. The optimum output capacitance for
most applications is 1µF, although larger values work as
well. This capacitor affects the turn-on and settling time
for the output to reach its final value.
Figure 1 shows the turn-on time for the LT6654-2.5 with a
0.1µF input bypass and 1µF load capacitor. Figure 2 shows
the output response to a 0.5V transient on VIN with the
same capacitors.
The test circuit of Figure 3 is used to measure the stability
with various load currents. With RL = 1k, the 1V step produces a current step of 1mA. Figure 4 shows the response
to a ± 0.5mA load. Figure 5 is the output response to a
sourcing step from 4mA to 5mA, and Figure  6 is the output
response of a sinking step from 4mA to 5mA.
VIN
0.5V/DIV
3V/DC
VIN
1V/DIV
GND
VOUT
2mV/DIV/AC
2.5V/DC
VOUT
1V/DIV
GND
CLOAD = 1µF
6654 F01
20µs/DIV
CLOAD = 1µF
Figure 1. Turn-On Characteristics of LT6654-2.5
VIN
3V
4
CIN
0.1µF
50µs/DIV
6654 F02
Figure 2. Output Response to 0.5V Ripple on VIN
LT6654-2.5
1, 2
6
1k
CL
1µF
VGEN
1V
6654 F03
Figure 3. Load Current Response Time Test Circuit
6654fb
10
LT6654
Applications Information
Positive or Negative Operation
IOUT
–0.5mA
In addition to the series connection, as shown on the front
page of this data sheet, the LT6654 can be operated as a
negative voltage reference.
0.5mA
VOUT
20mV/DIV/AC
2.5V/DC
CLOAD = 1µF
50µs/DIV
6654 F04
Figure 4. LT6654-2.5 Sourcing and Sinking 0.5mA
The circuit in Figure 7 shows an LT6654 configured for
negative operation. In this configuration, a positive voltage is required at VIN (Pin 4) to bias the LT6654 internal
circuitry. This voltage must be current limited with R1 to
keep the output PNP transistor from turning on and driving the grounded output. C1 provides stability during load
transients. This connection maintains the same accuracy and
temperature coefficient of the positive connected LT6654.
R1
4.7k
IOUT
4mA
3V
4
5mA
6
LT6654-2.5
0.1µF
1, 2
VOUT = –2.5V
VOUT
10mV/DIV/AC
2.5V/DC
V – VOUT
R ≤ EE
550µA + IOUT
C1
1µF
VEE
CLOAD = 1µF
50µs/DIV
6654 F05
6654 F07
Figure 7. Using the LT6654-2.5 to Build a –2.5V Reference
Figure 5. LT6654-2.5 Sourcing 4mA to 5mA
IOUT
–5mA
–4mA
VOUT
10mV/DIV/AC
2.5V/DC
CLOAD = 1µF
50µs/DIV
6654 F06
Figure 6. LT6654-2.5 Sinking 4mA to 5mA
6654fb
11
LT6654
Applications Information
Long-Term Drift
Long-term drift cannot be extrapolated from accelerated
high temperature testing. This erroneous technique
gives drift numbers that are wildly optimistic. The only
way long-term drift can be determined is to measure it
over the time interval of interest. The LT6654 drift data
was taken on 40 parts that were soldered into PC boards
similar to a real world application. The boards were then
placed into a constant temperature oven with TA = 35°C,
their outputs scanned regularly and measured with an 8.5
digit DVM. Long-term drift curves are shown in Figure 8.
Their drift is much smaller after the first thousand hours.
80
OUTPUT VOLTAGE CHANGE (ppm)
OUTPUT VOLTAGE CHANGE (ppm)
80
40
0
–40
–80
0
200
400
600
TIME (HOURS)
LONG TERM DRIFT:
FIRST THOUSAND HOURS
800
1000
6654 F08a
40
0
–40
–80
1000
2000
1400
1600
1800
TIME (HOURS)
6654 F08b
LONG TERM DRIFT:
SECOND THOUSAND HOURS
(NORMALIZED TO THE FIRST THOUSAND HOURS)
1200
Figure 8. LT6654-2.5 Long Term Drift
6654fb
12
LT6654
Applications Information
Power Dissipation
The LT6654 includes output current limit circuitry, as well
as thermal limit circuitry, to protect the reference from
damage in the event of excessive power dissipation. The
LT6654 is protected from damage by a thermal shutdown
circuit. However, changes in performance may occur as
a result of operation at high temperature.
T = 150°C
θJA = 192°C/W
0.6
POWER (W)
0.5
0.4
0.3
130mW
0.2
0.1
0
0
20
40
60
80
100
TEMPERATURE (°C)
140
Figure 9. Maximum Allowed Power Dissipation of the LT6654
0.40
335mW
0.35
0.30
0.25
10mA LOAD
0.20
0.15
0.10
0.05
0
NO LOAD
5
0
10
Hysteresis
15
20 25
VIN (V)
30
35
40
6654 F10
Figure 10. Typical Power Dissipation of the LT6654
50
MAX AVG HOT CYCLE MAX AVG COLD CYCLE
25°C TO 125°C TO 25°C 25°C TO –40°C TO 25°C
40
NUMBER OF UNITS
The hysteresis data is shown in Figure 11. The LT6654 is
capable of dissipating relatively high power. For example,
with a 36V input voltage and 10mA load current applied
to the LT6654-2.5, the power dissipation is PD = 33.5V
• 10mA = 335mW, which causes an increase in the die
temperature of 64°C. This could increase the junction
temperature above 125°C (TJMAX is 150°C) and may cause
the output to shift due to thermal hysteresis.
120
6654 F09
POWER (W)
The power dissipation in the LT6654 is dependent on VIN,
load current and the package. The LT6654 package has
a thermal resistance, or θJA, of 192°C/W. A curve that
illustrates allowed power dissipation versus temperature
for the 6-lead SOT-23 package is shown in Figure 9. The
power dissipation of the LT6654-2.5 as a function of input
voltage is shown in Figure 10. The top curve shows power
dissipation with a 10mA load and the bottom curve shows
power dissipation with no load. When operated within
its specified limits of VIN = 36V and sourcing 10mA, the
LT6654-2.5 consumes about 335mW at room temperature.
The power-derating curve in Figure 9 shows the LT66542.5 can only safely dissipate 130mW at 125°C, which is
less than its maximum power output. Care must be taken
when designing the circuit so that the maximum junction
temperature is not exceeded. For best performance, junction temperature should be kept below 125°C.
0.7
30
20
10
0
–150
–100
–50
0
50
100
DISTRIBUTION (ppm)
150
6654 F11
Figure 11. Thermal Hysteresis –40°C to 125°C
6654fb
13
LT6654
Applications Information
PC Board Layout
IR Reflow Shift
The mechanical stress of soldering a surface mount voltage reference to a PC board can cause the output voltage
to shift and temperature coefficient to change. These two
changes are not correlated. For example, the voltage may
shift but the temperature coefficient may not.
The different expansion and contraction rates of the materials that make up the LT6654 package may cause the
output voltage to shift after undergoing IR reflow. Lead
free solder reflow profiles reach over 250°C, considerably
more than with lead based solder. A typical lead free IR
reflow profile is shown in Figure 12. Similar profiles are
found using a convection reflow oven. LT6654 devices run
up to three times through this reflow process show that the
standard deviation of the output voltage increases with a
slight negative mean shift of 0.003% as shown in Figure 13.
While there can be up to 0.014% of output voltage shift,
the overall drift of the LT6654 after IR reflow does not
vary significantly.
To reduce the effects of stress-related shifts, mount the
reference near the short edge of the PC board or in a
corner. In addition, slots can be cut into the board on
two sides of the device.
The capacitors should be mounted close to the LT6654.
The GND and VOUT traces should be as short as possible
to minimize I • R drops, since high trace resistance directly
impacts load regulation.
380s
14
TP = 260°C
TL = 217°C
TS(MAX) = 200°C
TS = 190°C
225
RAMP
DOWN
tP
30s
T = 150°C
150
tL
130s
RAMP TO
150°C
75
40s
120s
0
0
2
4
6
MINUTES
12
NUMBER OF UNITS
TEMPERATURE (°C)
300
260°C 3 CYCLES
260°C 1 CYCLE
10
8
6
4
2
8
10
6654 F12
Figure 12. Lead Free Reflow Profile
0
–140 –120 –100 –80 –60 –40 –20
CHANGE IN OUTPUT (ppm)
0
6654 F13
Figure 13. Output Voltage Shift Due to IR Reflow (%)
6654fb
14
LT6654
Typical Applications
Extended Supply Range Reference
Boosted Output Current Reference
4.5V < VIN < 36V
UP TO 160V
4.7µF
220Ω
330k
MMBT5551
2N2905
IN
BZX84C12
LT6654-2.5
0.1µF
IOUT
UP TO 300mA
LT6654-2.5 OUT
1µF
1µF
6654 TA02
6654 TA03
Boosted Output Current with Current Limit
Octal DAC Reference
4.5V < VIN < 36V
LT6654-2.5
2.65V < VIN < 5V
IN
OUT
VIN
1
LED1*
4.7µF
220Ω
0.1µF
10Ω
10µF
2
VREF
2N2905
VCC
CS
LT6654-2.5
IN
IOUT
UP TO 100mA
OUT
1µF
SCK
0.1µF
DAC A
LTC2600 DAC B
SDI
DAC C
CLEAR
DAC D
DAC E
6654 TA04
DAC F
*LED CANNOT BE OMMITTED
THE LED CLAMPS THE VOLTAGE
DROP ACROSS THE 220Ω AND
LIMITS OUTPUT CURRENT
DAC G
GND
DAC H
6654 TA05
6654fb
15
LT6654
Package Description
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
0.62
MAX
2.90 BSC
(NOTE 4)
0.95
REF
1.22 REF
3.85 MAX 2.62 REF
1.4 MIN
2.80 BSC
1.50 – 1.75
(NOTE 4)
PIN ONE ID
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45
6 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
0.01 – 0.10
1.00 MAX
DATUM ‘A’
0.30 – 0.50 REF
0.09 – 0.20
(NOTE 3)
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
1.90 BSC
S6 TSOT-23 0302 REV B
6654fb
16
LT6654
Revision History
REV
DATE
DESCRIPTION
PAGE NUMBER
A
12/10
Added voltage options (1.250V, 2.048V, 3.000V, 4.096V, 5.000V) reflected throughout the data sheet.
B
3/11
Revised conditions for Output Voltage Noise in the Electrical Characteristics section.
1-18
4
6654fb
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.
17
LT6654
Typical Application
16-Bit ADC Reference
4.6V < VS < 36V
LT6654-4.096
IN
OUT
10µF
0.1µF
+
IN+
–2.048V < VDIFFERENTIAL < 2.048V
–
VREF
VCC
LTC2480
IN–
GND
fO
SDO
SDI
CS
TO MCU
SCK
6654 TA06
Related Parts
PART NUMBER DESCRIPTION
COMMENTS
LT1460
Micropower Series Reference
0.075% Max, 10ppm/°C Max Drift, 2.5V, 5V and 10V Versions, MSOP, PDIP, S0-8,
SOT-23 and TO-92 Packages
LT1461
Micropower Precision LDO Series Reference
3ppm/°C Max Drift, 0°C to 70°C, –40°C to 85°C, –40°C to 125°C Options in SO-8
LT1790
Micropower Precision Series References
0.05% Max, 10ppm/°C Max, 60µA Supply, SOT-23 Package
LT6650
Micropower Reference with Buffer Amplifier
0.05% Max, 5.6µA Supply, SOT-23 Package
LTC6652
Precision Low Drift Low Noise Buffered
Reference
0.5% Max, 5ppm/°C Max, 2.1ppmP-P Noise (0.1Hz to 10Hz) 100% Tested at –40°C,
25°C and 125°C
LT6660
Tiny Micropower Series Reference
0.2% Max, 20ppm/°C Max, 20mA Output Current, 2mm × 2mm DFN
LTC6655
Precision Low Noise Reference
2ppm/°C Max, 650nVP-P Noise (0.1Hz to 10Hz) 100% Tested at –40°C, 25°C and 125°C
LT6656
800nA Precision Voltage Reference
800nA, 10ppm/°C Max, 0.05% Max, SOT-23 Package
6654fb
18 Linear Technology Corporation
LT 0311 REV B • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2010