LINER LTC6652AHMS8-5-PBF

LTC6652
Precision Low Drift
Low Noise
Buffered Reference
FEATURES
DESCRIPTION
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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, highperformance industrial and other high temperature
applications.
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Low Drift: A Grade 5ppm/°C Max
B Grade 10ppm/°C Max
High Accuracy: A Grade ±0.05%, B Grade ±0.1%
Low Noise: 2.1ppmp-p (0.1Hz to 10Hz)
100% Tested at –40°C, 25°C and 125°C
Sinks and Sources Current: ±5mA
Low Power Shutdown: <2μA Maximum
Thermal Hysteresis: 105ppm for –40°C to 125°C
Range
Low Dropout: 300mV
No External Load Capacitor Required
Wide Supply Range to 13.2V
Available Output Voltage Options: 1.25V, 2.048V,
2.5V, 3V, 3.3V, 4.096V, 5V
8-Lead MSOP Package
APPLICATIONS
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Automotive Control and Monitoring
High Temperature Industrial
High Resolution Data Acquisition Systems
Instrumentation and Process Control
Precision Regulators
Medical Equipment
The LTC6652 voltage references can be powered from a
13.2V supply or as little as 300mV above the output voltage
or 2.7V; whichever is higher. The LTC6652 references
are offered in an 8-Lead MSOP package. They boast low
noise, excellent 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
reference is not needed. The optional output capacitor can
be left off when space constraints are critical.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Output Voltage Temperature Drift
0.050
2.8V b VIN b 13.2V
CIN
0.1MF
(OPTIONAL)
VIN
SHDN
VOUT
2.5V
LTC6652-2.5 VOUT
GND
COUT
1MF
(OPTIONAL)
6652 TA01a
VOUT ACCURACY (%)
Basic Connection
0.025
0
–0.025
–0.050
–40 –20
0
20 40 60 80
TEMPERATURE (°C)
100
125
6652 TA01b
6652fb
1
LTC6652
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
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
TOP VIEW
DNC
VIN
SHDN
GND
1
2
3
4
8
7
6
5
GND*
GND*
VOUT
GND*
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)
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
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
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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/
AVAILABLE OPTIONS
OUTPUT VOLTAGE
1.250
INITIAL ACCURACY
TEMPERATURE COEFFICIENT
0.05%
5ppm/°C
0.1%
10ppm/°C
2.048
0.05%
5ppm/°C
0.1%
10ppm/°C
2.500
0.05%
5ppm/°C
0.1%
10ppm/°C
3.000
0.05%
5ppm/°C
0.1%
10ppm/°C
3.300
0.05%
5ppm/°C
0.1%
10ppm/°C
4.096
0.05%
5ppm/°C
0.1%
10ppm/°C
5.000
0.05%
5ppm/°C
0.1%
10ppm/°C
**See Order Information section for complete part number listing.
2
PART NUMBER**
LTC6652AHMS8-1.25
LTC6652BHMS8-1.25
LTC6652AHMS8-2.048
LTC6652BHMS8-2.048
LTC6652AHMS8-2.5
LTC6652BHMS8-2.5
LTC6652AHMS8-3
LTC6652BHMS8-3
LTC6652AHMS8-3.3
LTC6652BHMS8-3.3
LTC6652AHMS8-4.096
LTC6652BHMS8-4.096
LTC6652AHMS8-5
LTC6652BHMS8-5
6652fb
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.
PARAMETER
Output Voltage
Output Voltage Temperature Coefficient
(Note 3)
Line Regulation
Load Regulation (Note 4)
Minimum Operating Voltage (Note 5)
Output Short-Circuit Current
Shutdown Pin (SHDN)
Supply Current
Shutdown Current
Output Voltage Noise (Note 6)
CONDITIONS
LTC6652A
LTC6652B
LTC6652A
LTC6652B
VOUT + 0.5V ≤ VIN ≤ 13.2V, SHDN = VIN
ISOURCE = 5mA, LTC6652-1.25, LTC6652-2.048,
LTC6652-2.5, LTC6652-3, LTC6652-3.3, LTC66524.096, LTC6652-5
ISINK = 1mA, LTC6652-1.25, LTC6652-2.048
ISINK = 5mA, LTC6652-2.5, LTC6652-3,
LTC6652-3.3, LTC6652-4.096, LTC6652-5
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
Short VOUT to GND
Short VOUT to VIN
Logic High Input Voltage
Logic High Input Current
Logic Low Input Voltage
Logic Low Input Current
No Load
SHDN Tied to GND
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
0.1% Settling, CLOAD = 0
Turn-On Time
Long Term Drift of Output Voltage (Note 7)
Hysteresis (Note 8)
ΔT = –40°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 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
MIN
–0.05
–0.1
l
l
2
4
2
l
20
l
80
l
50
l
l
l
TYP
MAX
0.05
0.1
5
10
50
80
75
200
UNITS
%
%
ppm/°C
ppm/°C
ppm/V
ppm/V
ppm/mA
ppm/mA
250
600
150
450
ppm/mA
ppm/mA
ppm/mA
ppm/mA
V
V
2.7
VOUT + 0.3V
16
16
l
l
l
l
l
l
2
0.1
0.1
350
0.1
2.4
2.1
2.2
2.3
2.8
3
100
60
105
1
0.8
1
560
2
mA
mA
V
μA
V
μA
μA
μA
μA
ppmP-P
ppmP-P
ppmP-P
ppmP-P
ppmP-P
ppmRMS
μs
ppm/√khr
ppm
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.
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.
6652fb
3
LTC6652
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.
1.25V Output Voltage
Temperature Drift
1.25V Line Regulation
1.25V Load Regulation (Sourcing)
1.2506
3 TYPICAL PARTS
0
OUTPUT VOLTAGE (V)
REFERENCE VOLTAGE (V)
1.2504
1.2505
1.2500
1.2495
125°C
1.2502
1.2500
25°C
1.2498
–40°C
1.2496
1.2490
–80
80
40
0
TEMPERATURE (°C)
–40
160
120
–40oC
OUTPUT VOLTAGE CHANGE (ppm)
1.2510
–50
125oC
–150
–200
1.2494
0
2
8
6
10
4
INPUT VOLTAGE (V)
6652 G17
12
–250
14
10
1
OUTPUT CURRENT (mA)
0.1
6652 G18
6652 G19
1.25V Low Frequency 0.1Hz to
10Hz Transient Noise
1.25V Load Regulation (Sinking)
1.25V Output Voltage Noise
Spectrum
400
400
350
125°C
300
250
200
25°C
150
100
NOISE VOLTAGE (nV/√Hz)
OUTPUT NOISE (1μV/DIV)
OUTPUT VOLTAGE CHANGE (ppm)
25oC
–100
300
200
100
–40°C
50
0
0.1
1
OUTPUT CURRENT (mA)
10
0
0.01
TIME (1 SECOND/DIV)
6652 G20
0.1
1
FREQUENCY (kHz)
10
6652 G22
6652 G21
1.25 Sinking Current Without
Output Capacitor
1.25 Sinking Current with Output
Capacitor
1.25V Stability with Output
Capacitance
10μF
IOUT
1mA
IOUT
0mA
VOUT
500mV/DIV
1μF
0mA
OUTPUT CAPACITOR
1mA
VOUT
500mV/DIV
500μs/DIV
COUT = 0μF
6652 G23
500μs/DIV
6652 G24
0.1μF
10nF
REGION OF
MARGINAL
STABILITY
1nF
100pF
COUT = 1μF
NO CAP
–5
–1 0
LOAD CURRENT (mA)
5
6652 G16
6652fb
4
LTC6652
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.
2.5V Output Voltage
Temperature Drift
2.5010
2.5V Line Regulation
2.5V Load Regulation (Sourcing)
0
2.5010
3 TYPICAL PARTS
OUTPUT VOLTAGE CHANGE (ppm)
2.5005
OUTPUT VOLTAGE (V)
REFERENCE VOLTAGE (V)
–20
2.5005
2.5000
2.4995
2.4990
2.5000
125°C
25°C
2.4995
–40°C
2.4990
2.4985
–40°C
–40
–60
25°C
–80
125°C
–100
–120
–140
–160
–180
2.4985
–50 –25
0
25 50
75 100 125 150
TEMPERATURE (°C)
–200
2.4980
0
2
8
6
10
4
INPUT VOLTAGE (V)
12
6652 G01
2.5V Supply Current
vs Input Voltage
0.9
800
0.8
400
125°C
25°C
–40°C
700
600
500
125°C
25°C
400
300
–40°C
1
OUTPUT CURRENT (mA)
2
8
6
4
10
INPUT VOLTAGE (V)
12
125°C
0.4
0.3
0.1
25°C
–40°C
0
14
0
2
8
6
4
10
INPUT VOLTAGE (V)
6652 G05
6652 G04
2.5V Minimum VIN-VOUT
Differential (Sourcing)
12
14
6652 G06
2.5V Minimum VOUT-VIN
Differential (Sinking)
10
10
1
0.1
0.5
0.2
0
10
0.6
100
OUTPUT CURRENT (mA)
0.1
0.7
200
0
0
SUPPLY CURRENT (μA)
1.0
900
SUPPLY CURRENT (μA)
500
2.5V Shutdown Current
vs Input Voltage
1000
600
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE CHANGE (ppm)
700
100
6652 G03
6652 G02
2.5V Load Regulation (Sinking)
200
10
1
OUTPUT CURRENT (mA)
0.1
14
25°C
1
25°C
125°C, –40°C
125°C
–40°C
0.01
0.001
0.01
0.1
1
INPUT-OUTPUT VOLTAGE (V)
6652 G09
0.1
0.001
0.01
0.1
OUTPUT-INPUT VOLTAGE (V)
1
6652 G10
6652fb
5
LTC6652
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.
2.5V Low Frequency 0.1Hz to
10Hz Transient Noise
2.5V Output Voltage Noise
Spectrum
600
NOISE VOLTAGE (nV/√Hz)
OUTPUT NOISE (1μV/DIV)
500
400
300
200
100
0
0.01
TIME (1 SECOND/DIV)
0.1
1
FREQUENCY (kHz)
6652 G12
6652 G11
Stability with Output Capacitance
(LTC6652-2.5, LTC6652-3,
LTC6652-3.3, LTC6652-4.906,
LTC6652-5)
Typical VOUT Distribution for
LTC6652-2.5
180
10μF
1004 UNITS
160
1μF
LTC6652A LIMITS
OUTPUT CAPACITOR
NUMBER OF UNITS
140
10
120
80
60
0.1μF
10nF
REGION OF
MARGINAL STABILITY
1nF
40
100pF
20
0
2.4985
2.4995
2.5005
OUTPUT VOLTAGE (V)
2.5015
NO CAP
–5
0
LOAD CURRENT (mA)
5
6652 G15
6652 G14
6652fb
6
LTC6652
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.
5V Output Voltage
Temperature Drift
5.005
5V Supply Current
vs Input Voltage
5V Line Regulation
5.002
3 TYPICAL PARTS
1000
5.000
4.998
800
5.001
SUPPLY CURRENT (μA)
OUTPUT VOLTAGE (V)
5.003
25°C
5.000
125°C
4.999
700
600
500
125°C
400
25°C
300
–40°C
200
–40°C
100
4.995
–50 –25
4.998
0
25 50
75 100 125 150
TEMPERATURE (°C)
0
8
6
10
4
INPUT VOLTAGE (V)
2
5V Shutdown Current
vs Input Voltage
14
0
0
2
8
6
4
10
INPUT VOLTAGE (V)
14
12
6652 G27
5V Minimum VIN to VOUT
Differential (Sourcing)
5V Low Frequency 0.1Hz to 10Hz
Transient Noise
10
1.0
0.9
OUTPUT CURRENT (mA)
0.7
0.6
0.5
0.4
0.3
–40°C
0.2
OUTPUT NOISE (5μV/DIV)
125°C
0.8
SUPPLY CURRENT (μA)
12
6652 G26
6652 G25
1
25°C
0.1
–40°C
0.1
125°C
25°C
0
0
2
8
6
4
10
INPUT VOLTAGE (V)
12
14
0.01
0.001
0.01
0.1
1
TIME (1 SECOND/DIV)
INPUT-OUTPUT VOLTAGE (V)
6652 G30
6652 G29
6652 G31
5V Start-Up Response Without
Output Capacitor
5V Output Voltage Noise Spectrum
5V Start-Up Response with Output
Capacitor
1000
NOISE VOLTAGE (nV/√Hz)
REFERENCE VOLTAGE (V)
900
800
VIN
2V/DIV
VIN
2V/DIV
VOUT
2V/DIV
VOUT
2V/DIV
600
400
200
100μs/DIV
COUT = 0μF
0
0.01
0.1
1
FREQUENCY (kHz)
6652 G33
100μs/DIV
6652 G34
COUT = 1μF
10
6652 G32
6652fb
7
LTC6652
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
100
0
COUT = 1μF
–40
–50
–60
COUT = 10μF
–70
VTH(UP)
2.0
10
VTRIP (V)
–20
–30
2.5
COUT = 0μF
COUT = 0μF
–10
OUTPUT IMPEDANCE (Ω)
POWER SUPPLY REJECTION RATIO (dB)
SHDN Input Voltage Thresholds
vs VIN
Output Impedance vs Frequency
COUT = 1μF
COUT = 10μF
1.5
VTH(DN)
1.0
1
–80
0.5
–90
–100
0.01
0.1
1
10
FREQUENCY (kHz)
100
1000
0.1
0.01
0
0.1
1
10
FREQUENCY (kHz)
6652 G07
100
2
4
6
8
10
12
14
VIN (V)
6652 G08
6652 G13
PIN FUNCTIONS
DNC (Pin 1): Do Not Connect.
GND (Pin 4): Device Ground.
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.
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.
SHDN (Pin 3): Shutdown Input. This active low input
powers down the device to <2μA. For normal operation
tie this pin to VIN.
GND (Pins 5,7,8): Internal function. Ground these pins.
6652fb
8
LTC6652
BLOCK DIAGRAM
2
3
VIN
SHDN
+
VOUT
BANDGAP
6
–
4
GND
6652 BD
APPLICATIONS INFORMATION
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 capacitor 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.
VIN
3V
CIN
0.1μF
2, 3
LTC6652-2.5
6
100Ω
COUT
1μF
VGEN
0.5V
4, 5, 7, 8
6652 F01
Figure 1. Transient Load Test Circuit
6652fb
9
LTC6652
APPLICATIONS INFORMATION
3.5V
VIN
5mA
IOUT
3V
0mA
VOUT
500mV/DIV
VOUT
200mV/DIV
COUT = 0μF
500μs/DIV
6652 F02
COUT = 0μF
Figure 2. Transient Response Without Output Capacitor
VIN
250μs/DIV
6652 F05
Figure 5. LTC6652-2.5 Sinking
Current Without Output Capacitor
0mA
IOUT
–5mA
3.5V
3V
VOUT
500mV/DIV
VOUT
200mV/DIV
COUT = 1μF
500μs/DIV
6652 F03
COUT = 1μF
250μs/DIV
6652 F06
Figure 6. LTC6652-2.5 Sourcing Current
with Output Capacitor
Figure 3. Transient Response with 1μF Output Capacitor
5mA
0mA
IOUT
–5mA
IOUT
0mA
VOUT
50mV/DIV
VOUT
200mV/DIV
COUT = 0μF
250μs/DIV
Figure 4. LTC6652-2.5 Sourcing
Current Without Output Capacitor
6652 F04
COUT = 1μF
250μs/DIV
6652 F07
Figure 7. LTC6652-2.5 Sinking
Current with Output Capacitor
6652fb
10
LTC6652
APPLICATIONS INFORMATION
2.8V b VIN b 13.2V
C1
1μF
VIN
2V/DIV
R1
20k
VIN
LTC6652-2.5
SHDN
VOUT
VOUT
GND
TO μC
VOUT
1V/DIV
COUT = 0μF
100μs/DIV
2N7002
6652 F10
C2
1μF
Figure 10. Open-Drain Shutdown Circuit
6652 F08
Figure 8. Start-Up Response Without Output Capacitor
SHDN
1V/DIV
VIN
2V/DIV
VOUT
1V/DIV
VOUT
1V/DIV
ILOAD = 5mA
COUT = 1μF
100μs/DIV
6652 F09
Figure 9. Start-Up Response with 1μF Output Capacitor
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 undetectable 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 shutdown
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.
1ms/DIV
6652 F11
Figure 11. Shutdown Response with 5mA Load
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.
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
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 were scanned regularly
and measured with an 8.5 digit DVM. Long-term drift is
shown below in Figure 12.
6652fb
11
LTC6652
APPLICATIONS INFORMATION
80
35
LTC6652-2.5 MS8 PACKAGE
3 TYPICAL PARTS
60 TA = 35oC
125°C TO 25°C
NUMBER OF UNITS
40
ppm
–40°C TO 25°C
30
20
0
–20
25
20
15
10
5
–40
0
300
900
600
HOURS
1200
1500
0
–250
6652 F12
Figure 12. Long Term Drift
50
–150
–50
DISTRIBUTION (ppm)
150
6652 F13
Figure 13. Hysteresis Plot –40°C to 125°C
Hysteresis
IR Reflow Shift
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 LT6652-2.5, 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.
The different expansion and contraction rates of the materials that make up the lead-free LTC6652 package cause the
output voltage to shift after undergoing IR reflow. Leadfree 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 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.
PC Board Layout
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.
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.
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
6652fb
12
LTC6652
APPLICATIONS INFORMATION
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 cur380s
0.7
TP = 260°C
225
tP
30s
TS = 190°C
T = 150°C
150
tL
130s
RAMP TO
150°C
0.6
RAMP
DOWN
TL = 217°C
TS(MAX) = 200°C
DISSIPATION (W)
300
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 consumption of the package.
0.5
0.4
0.3
0.2
75
40s
0.1
120s
0
0
0
2
4
6
MINUTES
8
0
10
6652 F14
Figure 14. Lead-Free Reflow Profile
40
60
80 100
TEMPERATURE (°C)
120
140
6652 F16
Figure 16. Maximum Recommended Dissipation for LTC6652
10
0.06
TA = 25°C
0.05
8
0.04
POWER (W)
NUMBER OF UNITS
20
6
4
5mA LOAD
0.03
0.02
2
0.01
NO LOAD
0
0.002
0.010
0.018
–0.014 –0.006
OUTPUT VOLTAGE SHIFT DUE TO IR REFLOW (%)
0
2
4
6
8
VIN (V)
10
12
14
6652 F17
6652 F15
Figure 15. Output Voltage Shift Due to IR Reflow
Figure 17. Typical Power Dissipation of the LTC6652
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13
LTC6652
TYPICAL APPLICATIONS
Extended Supply Range Reference
Extended Supply Range Reference
6V TO 160V
4V TO 30V
R1
330k
R2
4.7k
ON SEMI
MMBT5551
R1
VIN
BZX84C18
SHDN
C1
0.1μF
VOUT
LTC6652-2.5 VOUT
VIN
GND
C2
OPTIONAL
6652 TA02
SHDN
VOUT
LTC6652-2.5 VOUT
BZX84C18
C1
0.1μF
GND
6652 TA03
C2
OPTIONAL
Boosted Output Current
Negative Rail Circuit
V+ r (VOUT + 1.8V)
2, 3, 6
C1
1μF
LTC6652-2.5
6652 TA06
R1
2207
2N2905
VIN
SHDN
4, 5, 7, 8
–2.5V
100Ω
–3.5V
1μF
LTC6652-2.5 VOUT
VOUT
C2
1μF
GND
6652 TA04
6652fb
14
LTC6652
PACKAGE DESCRIPTION
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660 Rev F)
0.889 ± 0.127
(.035 ± .005)
5.23
(.206)
MIN
3.20 – 3.45
(.126 – .136)
3.00 ± 0.102
(.118 ± .004)
(NOTE 3)
0.65
(.0256)
BSC
0.42 ± 0.038
(.0165 ± .0015)
TYP
8
7 6 5
0.52
(.0205)
REF
RECOMMENDED SOLDER PAD LAYOUT
0.254
(.010)
3.00 ± 0.102
(.118 ± .004)
(NOTE 4)
4.90 ± 0.152
(.193 ± .006)
DETAIL “A”
0° – 6° TYP
GAUGE PLANE
1
0.53 ± 0.152
(.021 ± .006)
DETAIL “A”
2 3
4
1.10
(.043)
MAX
0.86
(.034)
REF
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
(.009 – .015)
TYP
0.65
(.0256)
BSC
0.1016 ± 0.0508
(.004 ± .002)
MSOP (MS8) 0307 REV F
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
6652fb
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.
15
LTC6652
TYPICAL APPLICATION
Improved Reference Supply Rejection in a Data Converter Application
LTC1657
16
D/A
DATA
VCC
GND
VDAC
REF
VIN
R1
50k
VOUT
LTC6652
REF
SHDN
C1
0.1μF
C2
10μF
GND
COUT
1μF
V1
V2
V3
V4
LTC1605
A/D
16
DOUT
GND
6652 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
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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
6652fb
16 Linear Technology Corporation
LT 1208 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 2007