LTC6652
1
6652fg
For more information www.linear.com/LTC6652
Features
applications
Description
Precision Low Drift Low
Noise Buffered Reference
The LTC
®
6652 family of precision, low drift, low noise
references is fully specified over the temperature range
of –40°C to 125°C. High order curvature compensation
allows these references to achieve a low drift of less than
5ppm/°C with a predictable temperature characteristic and
an output voltage accuracy of ±0.05%. The performance
over temperature should appeal to automotive, high perfor-
mance industrial and other high temperature applications.
The LTC6652 voltage references can be powered from
supply voltages up to 13.2V. They boast low noise, ex-
cellent load regulation, source and sink capability and
exceptional line rejection, making them a superior choice
for demanding precision applications. A shutdown mode
allows power consumption to be reduced when the refer-
ence is not needed. The optional output capacitor can be
left off when space constraints are critical.
The LTC6652 references are offered in an 8-lead MSOP
package and an 8-lead LS8 package. The LS8 is a 5mm
× 5mm surface mount hermetic package that provides
outstanding stability.
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.
Output Voltage Temperature Drift
n Low Drift:
A-Grade 5ppm/°C Max
B-Grade 10ppm/°C Max (MSOP8)
B-Grade 8ppm/°C Max (LS8)
n High Accuracy:
A-Grade ±0.05% Max
B-Grade ±0.1% Max
n Low Noise: 2.1ppmP-P (0.1Hz to 10Hz)
n 100% Tested at –40°C, 25°C and 125°C
n Sinks and Sources Current: ±5mA
n Low Power Shutdown: <2µA Maximum
n Thermal Hysteresis (LS8): 45ppm (–40°C to 125°C)
n Long-Term Drift (LS8): 20ppm/√kHr
n Low Dropout: 300mV
n Available Output Voltage Options: 1.25V, 2.048V, 2.5V,
3V, 3.3V, 4.096V, 5V
n 8-Lead MSOP and 5mm × 5mm Surface Mount
Hermetic Packages
n Automotive Control and Monitoring
n High Temperature Industrial
n High Resolution Data Acquisition Systems
n Instrumentation and Process Control
n Precision Regulators
n Medical Equipment
Basic Connection
typical application
TEMPERATURE (°C)
–40
–0.050
V
OUT
ACCURACY (%)
–0.025
0
0.025
0.050
–20 0 20 40
6652 TA01b
60 80 100
125
2.8V
≤ VIN ≤ 13.2V
CIN
0.1µF
(OPTIONAL)
COUT
1µF
(OPTIONAL)
V
OUT
2.5V
6652 TA01a
LTC6652-2.5 VOUT
VIN
GND
SHDN
LTC6652
2
6652fg
For more information www.linear.com/LTC6652
absolute MaxiMuM ratings
Input Voltage
VIN to GND .......................................... –0.3V to 13.2V
SHDN to GND ........................... –0.3V to (VIN + 0.3V)
Output Voltage
VOUT.......................................... –0.3V to (VIN + 0.3V)
Output Short-Circuit Duration ...................... Indefinite
Operating Temperature Range ................ –40°C to 125°C
Storage Temperature Range (Note 2) ..... –65°C to 150°C
Lead Temperature Range (Soldering, 10 sec)
(Note 9) .............................................................300°C
1
2
3
4
DNC
VIN
SHDN
GND
8
7
6
5
GND*
GND*
VOUT
GND*
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
TJMAX = 150°C, θJA = 200°C/W
DNC: DO NOT CONNECT
*CONNECT THE PINS TO DEVICE GND (PIN 4)
1
2
3
DNC
VIN
SHDN
7
6
5
GND*
VOUT
GND*
4
GND
8
GND*
TOP VIEW
LS8 PACKAGE
8-PIN LEADLESS CHIP CARRIER (5mm × 5mm)
TJMAX = 150°C, θJA = 120°C/W
DNC: DO NOT CONNECT
*CONNECT THE PINS TO DEVICE GND (PIN 4)
orDer inForMation
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE
LTC6652AHMS8-1.25#PBF LTC6652AHMS8-1.25#TRPBF LTCVH 8-Lead Plastic MSOP –40°C to 125°C
LTC6652BHMS8-1.25#PBF LTC6652BHMS8-1.25#TRPBF LTCVH 8-Lead Plastic MSOP –40°C to 125°C
LTC6652AHMS8-2.048#PBF LTC6652AHMS8-2.048#TRPBF LTCVJ 8-Lead Plastic MSOP –40°C to 125°C
LTC6652BHMS8-2.048#PBF LTC6652BHMS8-2.048#TRPBF LTCVJ 8-Lead Plastic MSOP –40°C to 125°C
LTC6652AHMS8-2.5#PBF LTC6652AHMS8-2.5#TRPBF LTCQV 8-Lead Plastic MSOP –40°C to 125°C
LTC6652BHMS8-2.5#PBF LTC6652BHMS8-2.5#TRPBF LTCQV 8-Lead Plastic MSOP –40°C to 125°C
LTC6652AHMS8-3#PBF LTC6652AHMS8-3#TRPBF LTCVK 8-Lead Plastic MSOP –40°C to 125°C
LTC6652BHMS8-3#PBF LTC6652BHMS8-3#TRPBF LTCVK 8-Lead Plastic MSOP –40°C to 125°C
LTC6652AHMS8-3.3#PBF LTC6652AHMS8-3.3#TRPBF LTCVM 8-Lead Plastic MSOP –40°C to 125°C
LTC6652BHMS8-3.3#PBF LTC6652BHMS8-3.3#TRPBF LTCVM 8-Lead Plastic MSOP –40°C to 125°C
LTC6652AHMS8-4.096#PBF LTC6652AHMS8-4.096#TRPBF LTCVN 8-Lead Plastic MSOP –40°C to 125°C
LTC6652BHMS8-4.096#PBF LTC6652BHMS8-4.096#TRPBF LTCVN 8-Lead Plastic MSOP –40°C to 125°C
LTC6652AHMS8-5#PBF LTC6652AHMS8-5#TRPBF LTCVP 8-Lead Plastic MSOP –40°C to 125°C
LTC6652BHMS8-5#PBF LTC6652BHMS8-5#TRPBF LTCVP 8-Lead Plastic MSOP –40°C to 125°C
pin conFiguration
(Note 1)
LTC6652
3
6652fg
For more information www.linear.com/LTC6652
OUTPUT VOLTAGE INITIAL ACCURACY TEMPERATURE COEFFICIENT PART NUMBER**
1.250 0.05%
0.1% 5ppm/°C
10ppm/°C LTC6652AHMS8-1.25
LTC6652BHMS8-1.25
2.048 0.05%
0.1% 5ppm/°C
10ppm/°C LTC6652AHMS8-2.048
LTC6652BHMS8-2.048
2.500 0.05%
0.1%
0.05%
0.1%
5ppm/°C
10ppm/°C
5ppm/°C
8ppm/°C
LTC6652AHMS8-2.5
LTC6652BHMS8-2.5
LTC6652AHLS8-2.5
LTC6652BHLS8-2.5
3.000 0.05%
0.1% 5ppm/°C
10ppm/°C LTC6652AHMS8-3
LTC6652BHMS8-3
3.300 0.05%
0.1% 5ppm/°C
10ppm/°C LTC6652AHMS8-3.3
LTC6652BHMS8-3.3
4.096 0.05%
0.1%
0.05%
0.1%
5ppm/°C
10ppm/°C
5ppm/°C
8ppm/°C
LTC6652AHMS8-4.096
LTC6652BHMS8-4.096
LTC6652AHLS8-4.096
LTC6652BHLS8-4.096
5.000 0.05%
0.1%
0.05%
0.1%
5ppm/°C
10ppm/°C
5ppm/°C
8ppm/°C
LTC6652AHMS8-5
LTC6652BHMS8-5
LTC6652AHLS8-5
LTC6652BHLS8-5
**See Order Information section for complete part number listing.
available options
electrical characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, VIN = VOUT + 0.5V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage LTC6652A
LTC6652B –0.05
–0.1 0.05
0.1 %
%
Output Voltage Temperature Coefficient
(Note 3) LTC6652A
LTC6652BMS8
LTC6652BLS8
l
l
l
2
4
4
5
10
8
ppm/°C
ppm/°C
ppm/°C
Line Regulation VOUT + 0.5V ≤ VIN ≤ 13.2V, SHDN = VIN
l
2 50
80 ppm/V
ppm/V
orDer inForMation
LEAD FREE FINISH PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE
LTC6652AHLS8-2.5#PBF†665225 8-Lead Ceramic LCC 5mm × 5mm –40°C to 125°C
LTC6652BHLS8-2.5#PBF†665225 8-Lead Ceramic LCC 5mm × 5mm –40°C to 125°C
LTC6652AHLS8-4.096#PBF†524096 8-Lead Ceramic LCC 5mm × 5mm –40°C to 125°C
LTC6652BHLS8-4.096#PBF†524096 8-Lead Ceramic LCC 5mm × 5mm –40°C to 125°C
LTC6652AHLS8-5#PBF†66525 8-Lead Ceramic LCC 5mm × 5mm –40°C to 125°C
LTC6652BHLS8-5#PBF†66525 8-Lead Ceramic LCC 5mm × 5mm –40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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/
†This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
LTC6652
4
6652fg
For more information www.linear.com/LTC6652
electrical characteristics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, VIN = VOUT + 0.5V, unless otherwise noted.
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 3-pole highpass at 0.1Hz
and 4-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 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) it’s usually not a dominant error
source.Typical hysteresis is the worst-case of 25°C to cold to 25°C or 25°C
to hot to 25°C, preconditioned by one thermal cycle.
Note 9: The stated temperature is typical for soldering of the leads during
manual rework. For detailed IR reflow recommendations, refer to the
Applications section.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Load Regulation (Note 4) ISOURCE = 5mA, LTC6652-1.25, LTC6652-2.048,
LTC6652-2.5, LTC6652-3, LTC6652-3.3,
LTC6652-4.096, LTC6652-5
l
20 75
200 ppm/mA
ppm/mA
ISINK = 1mA, LTC6652-1.25, LTC6652-2.048
l
80 250
600 ppm/mA
ppm/mA
ISINK = 5mA, LTC6652-2.5, LTC6652-3,
LTC6652-3.3, LTC6652-4.096, LTC6652-5
l
50 150
450 ppm/mA
ppm/mA
Minimum Operating Voltage (Note 5) ISOURCE = 5mA, VOUT Error ≤ 0.1%
LTC6652-1.25, LTC6652-2.048
LTC6652-2.5, LTC6652-3, LTC6652-3.3,
LTC6652-4.096, LTC6652-5
l
l
2.7
VOUT + 0.3V
V
V
Output Short-Circuit Current Short VOUT to GND
Short VOUT to VIN
16
16 mA
mA
Shutdown Pin (SHDN) Logic High Input Voltage
Logic High Input Current
l
l
2
0.1
1V
µA
Logic Low Input Voltage
Logic Low Input Current
l
l
0.1 0.8
1V
µA
Supply Current No Load
l
350
560 µA
µA
Shutdown Current SHDN Tied to GND l0.1 2 µA
Output Voltage Noise (Note 6) 0.1Hz ≤ f ≤ 10Hz
LTC6652-1.25
LTC6652-2.048, LTC6652-2.5, LTC6652-3
LTC6652-3.3
LTC6652-4.096
LTC6652-5
10Hz ≤ f ≤ 1kHz
2.4
2.1
2.2
2.3
2.8
3
ppmP-P
ppmP-P
ppmP-P
ppmP-P
ppmP-P
ppmRMS
Turn-On Time 0.1% Settling, CLOAD = 0 100 µs
Long-Term Drift of Output Voltage (Note 7) LTC6652MS8
LTC6652LS8 60
20 ppm/√kHr
ppm/√kHr
Hysteresis (Note 8) ∆T = –40°C to 125°C, LTC6652MS8
∆T = –40°C to 85°C, LTC6652MS8
∆T = 0°C to 70°C, LTC6652MS8
∆T = –40°C to 125°C, LTC6652LS8
∆T = –40°C to 85°C, LTC6652LS8
∆T = 0°C to 70°C, LTC6652LS8
80
75
45
45
25
10
ppm
ppm
ppm
ppm
ppm
ppm
LTC6652
5
6652fg
For more information www.linear.com/LTC6652
FREQUENCY (kHz)
0.01
NOISE VOLTAGE (nV/√Hz)
0.1 1
10
6652 G22
300
200
100
0
400
TIME (1 SECOND/DIV)
OUTPUT NOISE (1µV/DIV)
6652 G21
INPUT VOLTAGE (V)
0
OUTPUT VOLTAGE (V)
1.2502
1.2504
1.2506
6 10
6652 G18
1.2500
1.2498
2 4 8 12
14
1.2496
1.2494
125°C
–40°C
25°C
typical perForMance characteristics
1.25V Load Regulation (Sinking)
1.25V Low Frequency 0.1Hz to
10Hz Transient Noise
1.25V Output Voltage Noise
Spectrum
1.25 Sinking Current Without
Output Capacitor
1.25 Sinking Current with Output
Capacitor
1.25V Output Voltage
Temperature Drift
1.25V Load Regulation (Sourcing)
1.25V Line Regulation
TEMPERATURE (°C)
–80
REFERENCE VOLTAGE (V)
1.2500
1.2505
1.2510
40
160
6652 G17
1.2495
1.2490 –40 0 80 120
3 TYPICAL PARTS
OUTPUT CURRENT (mA)
0.1
–250
–200
OUTPUT VOLTAGE CHANGE (ppm)
–150
–100
0
1
6652 G19
–50
10
125°C
25°C
–40°C
OUTPUT CURRENT (mA)
0.1
0
OUTPUT VOLTAGE CHANGE (ppm)
100
200
300
50
150
250
350
400
1
10
–40°C
125°C
6652 G20
25°C
500µs/DIV
VOUT
C
= 0µF
OUT
1mA
0mA
500µs/DIV
VOUT
C
= 1µF
OUT
1mA
0mA
6652 G24
LOAD CURRENT (mA)
NO CAP
OUTPUT CAPACITOR
100pF
1nF
10nF
0.1µF
1µF
10µF
–5 –1 0 5
6652 G16
REGION OF
MARGINAL
STABILITY
1.25V Stability with Output
Capacitance
Characteristic curves are similar for most
LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options.
Characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
LTC6652
6
6652fg
For more information www.linear.com/LTC6652
typical perForMance characteristics
2.5V Output Voltage
Temperature Drift
2.5V Load Regulation (Sourcing)
2.5V Load Regulation (Sinking)
2.5V Supply Current
vs Input Voltage
2.5V Shutdown Current
vs Input Voltage
2.5V Minimum VIN-VOUT
Differential (Sourcing)
TEMPERATURE (°C)
–50
REFERENCE VOLTAGE (V)
2.5000
2.5005
2.5010
25 75 150
6652 G01
2.4995
2.4990
2.4985 –25 0 50 100 125
3 TYPICAL PARTS
INPUT VOLTAGE (V)
0
OUTPUT VOLTAGE (V)
2.5000
2.5005
2.5010
6 10
6652 G02
2.4995
2.4990
2 4 8 12 14
2.4985
2.4980
125°C
–40°C
25°C
OUTPUT CURRENT (mA)
0.1
–200
OUTPUT VOLTAGE CHANGE (ppm)
–180
–140
–120
–100
0
–60
1
6652 G03
–160
–40
–20
–80
10
125°C
25°C
–40°C
OUTPUT CURRENT (mA)
0.1
0
OUTPUT VOLTAGE CHANGE (ppm)
100
200
400
500
600
700
1 10
–40°C
125°C
25°C
6652 G04
INPUT VOLTAGE (V)
0
0
SUPPLY CURRENT (µA)
100
300
400
500
1000
700
4810
6652 G05
200
800
900
600
2612
125°C
–40°C
14
25°C
INPUT VOLTAGE (V)
0
0
SUPPLY CURRENT (µA)
0.1
0.3
0.4
0.5
1.0
0.7
4810
6652 G06
0.2
0.8
0.9
0.6
2612 14
125°C
25°C
–40°C
INPUT-OUTPUT VOLTAGE (V)
0.001
0.01
OUTPUT CURRENT (mA)
1
10
0.01 0.1 1
6652 G09
0.1 25°C
125°C, –40°C
2.5V Line Regulation
Characteristic curves are similar for most
LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options.
Characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
2.5V Minimum VOUT-VIN
Differential (Sinking)
OUTPUT-INPUT VOLTAGE (V)
0.001
OUTPUT CURRENT (mA)
10
0.01 0.1 1
6652 G10
1
0.1
25°C
–40°C
125°C
LTC6652
7
6652fg
For more information www.linear.com/LTC6652
typical perForMance characteristics
Typical VOUT Distribution for
LTC6652-2.5
Stability with Output Capacitance
(LTC6652-2.5, LTC6652-3,
LTC6652-3.3, LTC6652-4.096,
LTC6652-5)
2.5V Low Frequency 0.1Hz to
10Hz Transient Noise
2.5V Output Voltage Noise
Spectrum
TIME (1 SECOND/DIV)
OUTPUT NOISE (1µV/DIV)
6652 G11
FREQUENCY (kHz)
0.01
NOISE VOLTAGE (nV/√Hz)
0.1 1 10
6652 G12
300
200
100
0
600
500
400
OUTPUT VOLTAGE (V)
2.4985
0
NUMBER OF UNITS
40
60
80
180
140
2.5005
6652 G15
20
160
120
2.4995 2.5015
LTC6652A LIMITS
1004 UNITS
LOAD CURRENT (mA)
NO CAP
OUTPUT CAPACITOR
100pF
1nF
10nF
0.1µF
1µF
10µF
–5 0 5
6652 G14
REGION OF
MARGINAL STABILITY
Characteristic curves are similar for most
LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options.
Characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
LTC6652
8
6652fg
For more information www.linear.com/LTC6652
FREQUENCY (kHz)
0.01
NOISE VOLTAGE (nV/√Hz)
0.1 1
10
6652 G32
200
0
1000
800
600
400
TIME (1 SECOND/DIV)
OUTPUT NOISE (5µV/DIV)
6652 G31
INPUT VOLTAGE (V)
0
0
SUPPLY CURRENT (µA)
0.1
0.3
0.4
0.5
1.0
0.7
4810
6652 G29
0.2
0.8
0.9
0.6
2612
14
125°C
–40°C
25°C
typical perForMance characteristics
5V Shutdown Current
vs Input Voltage
5V Minimum VIN to VOUT
Differential (Sourcing)
5V Low Frequency 0.1Hz to 10Hz
Transient Noise
5V Output Voltage Noise Spectrum
5V Start-Up Response Without
Output Capacitor
5V Output Voltage
Temperature Drift
5V Supply Current
vs Input Voltage
5V Line Regulation
5V Start-Up Response with Output
Capacitor
Characteristic curves are similar for most
LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options.
Characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
INPUT VOLTAGE (V)
0
OUTPUT VOLTAGE (V)
6 10
6652 G26
2 4 8 12
14
125°C
–40°C
25°C
5.000
5.001
5.002
4.999
4.998
TEMPERATURE (°C)
REFERENCE VOLTAGE (V)
5.000
5.003
5.005
6652 G25
4.998
4.995
–50 25 75
150
–25 0 50 100 125
3 TYPICAL PARTS
INPUT VOLTAGE (V)
0
0
SUPPLY CURRENT (µA)
100
300
400
500
1000
700
4810
6652 G27
200
800
900
600
2612
14
125°C
–40°C
25°C
INPUT-OUTPUT VOLTAGE (V)
0.001
0.01
OUTPUT CURRENT (mA)
1
10
0.01 0.1
1
6652 G30
0.1
25°C
125°C
–40°C
100µs/DIV
VOUT
2V/DIV
VIN
2V/DIV
C
OUT
= 0µF
6652 G33 100µs/DIV
VOUT
2V/DIV
VIN
2V/DIV
C
OUT
= 1µF
6652 G34
LTC6652
9
6652fg
For more information www.linear.com/LTC6652
pin Functions
DNC (Pin 1): Do Not Connect.
VIN (Pin 2): Power Supply. The minimum supply input is
VOUT + 300mV or 2.7V; whichever is higher. The maximum
supply is 13.2V. Bypassing VIN with a 0.1µF capacitor to
GND will improve PSRR.
SHDN (Pin 3): Shutdown Input. This active low input
powers down the device to <2µA. For normal operation
tie this pin to VIN.
GND (Pin 4): Device Ground.
VOUT (Pin 6): Output Voltage. An output capacitor is not
required. For some applications, a capacitor between 0.1µF
to 10µF can be beneficial. See the graphs in the Typical
Performance Characteristics section for further details.
GND (Pins 5,7,8): Internal Function. Ground these pins.
typical perForMance characteristics
Characteristic curves are similar for most
LTC6652s. Curves from the LTC6652-1.25, LTC6652-2.5 and the LTC6652-5 represent the extremes and typical of the voltage options.
Characteristic curves for other output voltages fall between these curves and can be estimated based on their output.
Power Supply Rejection Ratio
vs Frequency
Output Impedance vs Frequency
FREQUENCY (kHz)
0.01
–60
POWER SUPPLY REJECTION RATIO (dB)
–50
–40
–30
–20
0.1 1 10 100 1000
6652 G07
–70
–80
–90
–100
–10
0
COUT = 0µF
COUT = 1µF
COUT = 10µF
FREQUENCY (kHz)
1
OUTPUT IMPEDANCE (Ω)
10
100
0.01 1 10 100
6652 G08
0.1 0.1
COUT = 0µF
COUT = 1µF
COUT = 10µF
SHDN Input Voltage Thresholds
vs VIN
VIN (V)
2
VTRIP (V)
1.5
2.0
0.5
1.0
2.5
6 10
6652 G13
48 12 14
0
VTH(DN)
VTH(UP)
LTC6652
10
6652fg
For more information www.linear.com/LTC6652
Bypass and Load Capacitors
The LTC6652 voltage references do not require an input
capacitor, but a 0.1µF capacitor located close to the part
improves power supply rejection.
The LTC6652 voltage references are stable with or without
a capacitive load. For applications where an output capaci-
tor is beneficial, a value of 0.1µF to 10µF is recommended
depending on load conditions. The Typical Performance
Characteristics section includes a plot illustrating a region
of marginal stability. Either no or low value capacitors for
any load current are acceptable. For loads that sink current
or light loads that source current, a 0.1µF to 10µF capacitor
has stable operation. For heavier loads that source current
a 0.5µF to 10µF capacitor range is recommended.
The transient response for a 0.5V step on VIN with and
without an output capacitor is shown in Figures 2 and 3,
respectively.
The LTC6652 references with an output of 2.5V and above
are guaranteed to source and sink 5mA. The 1.25V and
2.048V versions are guaranteed to source 5mA and sink
1mA. The test circuit for transient load step response is
shown in Figure 1. Figures 4 and 5 show a 5mA source
and sink load step response without a load capacitor,
respectively.
Start-Up
The start-up characteristic of the LTC6652 is shown in
Figures 8 and 9. Note that the turn-on time is affected by
the value of the output capacitor.
block DiagraM
applications inForMation
VIN
SHDN
GND
VOUT
6652 BD
BANDGAP
3 6
2
4
–
+
Figure 1. Transient Load Test Circuit
VIN
3V
2, 3 6 100Ω
4, 5, 7, 8
CIN
0.1µF COUT
1µF VGEN 0.5V
6652 F01
LTC6652-2.5
LTC6652
11
6652fg
For more information www.linear.com/LTC6652
applications inForMation
Figure 2. Transient Response Without
Output Capacitor
Figure 3. Transient Response with 1µF
Output Capacitor
Figure 5. LTC6652-2.5 Sinking Current
Without Output Capacitor
Figure 6. LTC6652-2.5 Sourcing Current
with Output Capacitor
Figure 4. LTC6652-2.5 Sourcing
Current Without Output Capacitor
Figure 7. LTC6652-2.5 Sinking Current
with Output Capacitor
3.5V
3V
VOUT
500mV/DIV
500µs/DIV 6652 F02
COUT = 0µF
VIN 5mA
0mA
VOUT
200mV/DIV
250µs/DIV 6652 F05
COUT = 0µF
IOUT
3.5V
3V
VOUT
500mV/DIV
500µs/DIV 6652 F03
COUT = 1µF
VIN
VOUT
200mV/DIV
250µs/DIV 6652 F06
COUT = 1µF
0mA
–5mA
IOUT
0mA
–5mA
VOUT
200mV/DIV
250µs/DIV 6652 F04
COUT = 0µF
IOUT
5mA
0mA
VOUT
50mV/DIV
250µs/DIV 6652 F07
COUT = 1µF
IOUT
LTC6652
12
6652fg
For more information www.linear.com/LTC6652
applications inForMation
Figure 8. Start-Up Response without
Output Capacitor
Figure 9. Start-Up Response with 1µF
Output Capacitor
Figure 10. Open-Drain Shutdown Circuit
Figure 11. Shutdown Response with
5mA Load
In Figure 8, ripple momentarily appears just after the
leading edge of powering on. This brief one time event is
caused by calibration circuitry during initialization. When
an output capacitor is used, the ripple is virtually undetect-
able as shown in Figure 9.
Shutdown Mode
Shutdown mode is enabled by tying SHDN low which
places the part in a low power state (i.e., <2µA). In shut-
down mode, the output pin takes the value 20k • (rated
output voltage). For example, an LTC6652-2.5 will have
an output impedance of 20k • 2.5 = 50kΩ. For normal
operation, SHDN should be greater than or equal to 2.0V.
For use with a microcontroller, use a pull-up resistor to
VIN and an open-drain output driver as shown in Figure
10. The LTC6652’s response into and out of shutdown
mode is shown in Figure 11.
The trip thresholds on SHDN have some dependence on the
voltage applied to VIN as shown in the Typical Performance
Characteristics section. Be careful to avoid leaving SHDN
at a voltage between the thresholds as this will likely cause
an increase in supply current due to shoot-through current.
VIN
2V/DIV
VOUT
1V/DIV
100µs/DIV 6652 F08
COUT = 0µF
2.8V ≤ VIN ≤ 13.2V
VOUT
TO µC
C1
1µF
C2
1µF
R1
20k
6652 F10
LTC6652-2.5
SHDN
2N7002
VOUT
VIN
GND
VIN
2V/DIV
VOUT
1V/DIV
100µs/DIV 6652 F09
COUT = 1µF
SHDN
1V/DIV
VOUT
1V/DIV
1ms/DIV 6652 F11
ILOAD = 5mA
LTC6652
13
6652fg
For more information www.linear.com/LTC6652
applications inForMation
Figure 12a. MS8 Long-Term Drift
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 LTC6652 long-term drift
data was collected on more than 100 parts that were sol-
dered 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 were scanned regularly
and measured with an 8.5 digit DVM. Long-term drift is
shown below in Figure 12.
Figure 12b. LS8 Long-Term Drift
Hysteresis
The hysteresis data shown in Figure 13 represents the
worst-case data collected on parts from –40°C to 125°C.
The output is capable of dissipating relatively high power,
i.e., for the LTC6652-2.5, PD = 10.7V • 5.5mA = 58.85mW.
The thermal resistance of the MS8 package is 200°C/W
and this dissipation causes a 11.8°C internal rise. This
could increase the junction temperature above 125°C and
may cause the output to shift due to thermal hysteresis.
Figure 13a. MS8 Hysteresis Plot
–40°C to 125°C
Figure 13b. LS8 Hysteresis Plot
–40°C to 125°C
HOURS
0
ppm
60
80
600
6652 F12b
40
–20
20
200 400 800 1000
–40
0
LTC6652-2.5 LS8 PACKAGE
4 TYPICAL PARTS
TA = 30°C
HOURS
0
ppm
60
80
900
6652 F12a
40
–20
20
300 600 1200 1500
–40
0
LTC6652-2.5 MS8 PACKAGE
3 TYPICAL PARTS
TA = 35°C
DISTRIBUTION (ppm)
–110 –80 –50 –20 0 5020 80
0
NUMBER OF UNITS
2
3
4
5
9
7
6652 F13b
8
6
110
1
25°C TO 125°C TO 25°C
25°C TO –40°C TO 25°C
DISTRIBUTION (ppm)
–250 –150 –50
0
NUMBER OF UNITS
5
10
15
35
25
6652 F13a
30
20
15050
25°C TO 125°C TO 25°C25°C TO –40°C TO 25°C
LTC6652
14
6652fg
For more information www.linear.com/LTC6652
Figure 14. Lead-Free Reflow Profile
PC Board Layout
The mechanical stress of soldering a surface mount volt-
age 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.
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 package.
The GND and VOUT traces should be as short as possible
to minimize I • R drops. Excessive trace resistance directly
impacts load regulation.
IR Reflow Shift
The different expansion and contraction rates of the materi-
als that make up the lead-free LTC6652 package cause the
output voltage to shift after undergoing IR reflow. Lead-free
reflow profiles reach over 250°C, considerably more than
their leaded counterparts. The lead-free IR reflow profile
used to experimentally measure output voltage shift in the
LTC6652-2.5 is shown in Figure 14. Similar results can be
applications inForMation
expected using a convection reflow oven. In our experiment,
the serialized parts were run through the reflow process
twice. The results indicate that the standard deviation of
the output voltage increases with a slight positive mean
shift of 0.003% as shown in Figure 15. While there can
be up to 0.016% of output voltage shift, the overall drift
of the LTC6652 after IR reflow does not vary significantly.
Power Dissipation
Power dissipation in the LTC6652 is dependent on VIN,
load current, and package. The LTC6652 package has
a thermal resistance, or θJA, of 200°C/W. A curve that
illustrates allowed power dissipation vs temperature for
this package is shown in Figure 16.
The power dissipation of the LTC6652-2.5V as a function
of input voltage is shown in Figure 17. The top curve
shows power dissipation with a 5mA load and the bottom
curve shows power dissipation with no load.
When operated within its specified limits of VIN = 13.2V
and sourcing 5mA, the LTC6652-2.5 consumes just under
60mW at room temperature. At 125°C the quiescent cur-
rent will be slightly higher and the power consumption
increases to just over 60mW. The power-derating curve
in Figure 16 shows the LTC6652-2.5 can safely dissipate
125mW at 125°C about half the maximum power con-
sumption of the package.
Humidity Sensitivity
Plastic mould compounds absorb water. With changes
in relative humidity, plastic packaging materials change
the amount of pressure they apply to the die inside,
which can cause slight changes in the output of a volt-
age reference, usually on the order of 100ppm. The LS8
package is hermetic, so it is not affected by humidity, and
is therefore more stable in environments where humidity
may be a concern.
0246
MINUTES
8
0
75
150
225
300
6652 F14
10
120s
40s
tP
30s
TP = 260°C
RAMP
DOWN
RAMP TO
150°C
TS = 190°C
T = 150°C
tL
130s
TL = 217°C
TS(MAX) = 200°C
380s
LTC6652
15
6652fg
For more information www.linear.com/LTC6652
applications inForMation
Figure 16. Maximum Recommended
Dissipation for LTC6652
Figure 17. Typical Power Dissipation
of the LTC6652
TEMPERATURE (°C)
0
0
DISSIPATION (W)
0.2
0.6
0.1
80
0.7
6652 F16
0.4
0.3
0.5
40
20 100 120
60 140
VIN (V)
2
0
POWER (W)
0.01
0.03
0.04
0.05
0.06
6652 F17
0.02
6
410 12
8 14
TA = 25°C
5mA LOAD
NO LOAD
Figure 15a. MS8 Output Voltage
Shift Due to IR Reflow
OUTPUT VOLTAGE SHIFT DUE TO IR REFLOW (%)
–0.014 –0.006
0
NUMBER OF UNITS
4
2
6
10
8
6652 F15a
0.0180.0100.002
OUTPUT VOLTAGE SHIFT DUE TO IR REFLOW (%)
–0.1 –0.02–0.06
0
NUMBER OF UNITS
3
2
1
5
4
7
6
6652 F15b
0.1
0.060.020
1X
3X
Figure 15b. LS8 Output Voltage
Shift Due to IR Reflow
LTC6652
16
6652fg
For more information www.linear.com/LTC6652
typical applications
Extended Supply Range Reference Extended Supply Range Reference
Boosted Output Current
4V TO 30V
VOUT
BZX84C18 C1
0.1µF
C2
OPTIONAL
R1
6652 TA02
LTC6652-2.5 VOUT
VIN
GND
SHDN
6V TO 160V
VOUT
BZX84C18
C1
0.1µF
C2
OPTIONAL
R1
330k ON SEMI
MMBT5551
R2
4.7k
6652 TA03
LTC6652-2.5 VOUT
VIN
GND
SHDN
V
+
≥ (VOUT + 1.8V)
VOUT
C1
1µF
C2
1µF
R1
220Ω
6652 TA04
LTC6652-2.5
2N2905
VOUT
VIN
GND
SHDN
Negative Rail Circuit
V
EE
≤ –3V
V
CC
≥ 1.75V
VOUT
–2.5V
4, 5, 7, 8
2, 3
6
1µF
500Ω
6652 TA06
C1
0.1µF
LTC6652-2.5
LTC6652
17
6652fg
For more information www.linear.com/LTC6652
package Description
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660 Rev G)
Please refer to http://www.linear.com/product/LTC6652#packaging for the most recent package drawings.
MSOP (MS8) 0213 REV G
0.53 ±0.152
(.021 ±.006)
SEATING
PLANE
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
0.18
(.007)
0.254
(.010)
1.10
(.043)
MAX
0.22 – 0.38
(.009 – .015)
TYP
0.1016 ±0.0508
(.004 ±.002)
0.86
(.034)
REF
0.65
(.0256)
BSC
0° – 6° TYP
DETAIL “A”
DETAIL “A”
GAUGE PLANE
1 2 34
4.90 ±0.152
(.193 ±.006)
8765
3.00 ±0.102
(.118 ±.004)
(NOTE 3)
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
0.52
(.0205)
REF
5.10
(.201)
MIN
3.20 – 3.45
(.126 – .136)
0.889 ±0.127
(.035 ±.005)
RECOMMENDED SOLDER PAD LAYOUT
0.42 ± 0.038
(.0165 ±.0015)
TYP
0.65
(.0256)
BSC
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660 Rev G)
LTC6652
18
6652fg
For more information www.linear.com/LTC6652
package Description
Please refer to http://www.linear.com/product/LTC6652#packaging for the most recent package drawings.
LS8 Package
8-Pin Leadless Chip Carrier (5mm × 5mm)
(Reference LTC DWG # 05-08-1852 Rev B)
7
8
1
3
4
2
2.00 REF
R0.20 REF
6
5
7
8
6
5
1
2
3
4
4.20 ±0.10
4.20 SQ ±0.10
2.54 ±0.15
1.00 × 7 TYP
0.64 × 8 TYP
LS8 0113 REV B
R0.20 REF
0.95 ±0.10
1.45 ±0.10
0.10 TYP0.70 TYP
1
4
7
8
6
1.4
0.5
1.50 ±0.15
2.50 ±0.15
2.54 ±0.15
0.70 ±0.05 × 8
PACKAGE OUTLINE
0.5
5.00 SQ ±0.15
5.00 SQ ±0.15
5.00 SQ ±0.15
5.80 SQ ±0.15
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
NOTE:
1. ALL DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS PACKAGE DO NOT INCLUDE PLATING BURRS
PLATING BURRS, IF PRESENT, SHALL NOT EXCEED 0.30mm ON ANY SIDE
4. PLATING—ELECTO NICKEL MIN 1.25UM, ELECTRO GOLD MIN 0.30UM
5. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
PIN 1
TOP MARK
(SEE NOTE 5)
2
3
LS8 Package
8-Pin Leadless Chip Carrier (5mm × 5mm)
(Reference LTC DWG # 05-08-1852 Rev B)
ABCDEF
XYY ZZ
e4
Q12345
TRAY PIN 1
BEVEL PACKAGE IN TRAY LOADING ORIENTATION
COMPONENT
PIN “A1”
1.4
LTC6652
19
6652fg
For more information www.linear.com/LTC6652
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision history
REV DATE DESCRIPTION PAGE NUMBER
C 11/09 Change to Typical Performance Characteristics.
Change to Typical Application.
6
14
D 8/12 Addition of 5mm × 5mm Hermetic LS8 Package.
Update to Electrical Characteristics to Include LS8 Package.
Addition of Long Term Drift, Hysteresis, IR Drift Plots for LS8 Package.
Addition of Humidity Sensitivity Information.
1, 2, 3, 12, 18
4
13, 15
14
E 1/13 Correction to pin labeling of LS8 Package 2
F 7/15 Order Information updated to include 4.096V and 5V options in LS8 package.
MS8 and LS8 package descriptions updated.
3
17, 18
G 10/15 Correction to the Electrical Characteristics Table: Output Voltage Temperature Coefficient for LTC6652BMS8
specification applies over the full operating temperature range.
3
(Revision history begins at Rev C)
LTC6652
20
6652fg
For more information www.linear.com/LTC6652
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
LINEAR TECHNOLOGY CORPORATION 2007
LT 1015 REV G • PRINTED IN USA
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTC6652
typical application
PART NUMBER DESCRIPTION COMMENTS
LT1460 Micropower Series References 0.075% Max, 10ppm/°C Max, 20mA Output Current
LT1461 Micropower Series Low Dropout 0.04% Max, 3ppm/°C Max, 50mA Output Current
LT1790 Micropower Precision Series References 0.05% Max, 10ppm/°C Max, 60µA Supply, SOT23 Package
LT6650 Micropower Reference with Buffer Amplifier 0.5% Max, 5.6µA Supply, SOT23 Package
LT6660 Tiny Micropower Series Reference 0.2% Max, 20ppm/°C Max, 20mA Output Current, 2mm × 2mm DFN
LT6654 Precision Wide Supply High Output Drive Low Noise Reference 0.05% Max, 10ppm/°C Max, 10mA Output Current,
1.6ppmP-P Noise, SOT23 and LS8 Packages, –55°C to 125°C
LTC6655 Precision, Low Drift, Low Noise Reference 0.025% Max, 2ppm/°C Max, 5mA Output Current,
0.25ppmP-P Noise, –40°C to 125°C
Improved Reference Supply Rejection in a Data Converter Application
relateD parts
VOUT
COUT
1µF
C1
0.1µF
C2
10µF
R1
50k
6652 TA05
LTC6652
DATA
16
DOUT
SHDN V1
V2
V3
V4
VIN
VCC
REF
GND
GND
REFGND
D/A VDAC
A/D 16
LTC1657
LTC1605