LTC6652AHMS8-3.3-TRPBF [Linear]
Precision Low Drift Low Noise Buffered Reference; 精密,低漂移,低噪声缓冲基准型号: | LTC6652AHMS8-3.3-TRPBF |
厂家: | Linear |
描述: | Precision Low Drift Low Noise Buffered Reference |
文件: | 总16页 (文件大小:332K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC6652
Precision Low Drift
Low Noise
Buffered Reference
FEATURES
DESCRIPTION
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/°Cwithapredictabletemperaturecharacteristicand
an output voltage accuracy of 0.05ꢀ. The performance
over temperature should appeal to automotive, high-
performance industrial and other high temperature
applications.
n
Low Drift: A Grade 5ppm/°C Max
B Grade 10ppm/°C Max
n
High Accuracy: A Grade 0ꢀ05ꢁ% B Grade 0ꢀ1ꢁ
n
Low Noise: 2ꢀ1ppm (0ꢀ1Hz to 10Hz)
p-p
n
100ꢁ Tested at –40°C% 25°C and 125°C
n
Sinks and Sources Current: 5mA
n
Low Power Shutdown: <2μA Maximum
n
Thermal Hysteresis: 105ppm for –40°C to 125°C
Range
n
Low Dropout: 300mV
The LTC6652 voltage references can be powered from a
13.2Vsupplyoraslittleas300mVabovetheoutputvoltage
or 2.7V; whichever is higher. The LTC6652 references
are offered in an 8-Lead MSOP package. They boast low
noise, excellentloadregulation, sourceandsinkcapability
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.
n
No External Load Capacitor Required
n
Wide Supply Range to 13.2V
n
Available Output Voltage Options: 1.25V, 2.048V,
2.5V, 3V, 3.3V, 4.096V, 5V
8-Lead MSOP Package
n
APPLICATIONS
n
Automotive Control and Monitoring
n
High Temperature Industrial
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
n
High Resolution Data Acquisition Systems
Instrumentation and Process Control
Precision Regulators
Medical Equipment
n
n
n
TYPICAL APPLICATION
Output Voltage Temperature Drift
0.050
Basic Connection
0.025
0
V
OUT
V
V
OUT
LTC6652-2.5
GND
2.8V b V b 13.2V
IN
IN
2.5V
C
OUT
C
IN
SHDN
1MF
0.1MF
(OPTIONAL)
(OPTIONAL)
6652 TA01a
–0.025
–0.050
–40 –20
0
20 40 60 80 100 125
TEMPERATURE (°C)
6652 TA01b
6652fb
1
LTC6652
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
TOP VIEW
Input Voltage
DNC
IN
SHDN
GND
1
2
3
4
8 GND*
7 GND*
V to GND..........................................–0.3V to 13.2V
IN
V
SHDN to GND ............................–0.3V to (V + 0.3V)
IN
6 V
OUT
5 GND*
Output Voltage
V
...........................................–0.3V to (V + 0.3V)
MS8 PACKAGE
8-LEAD PLASTIC MSOP
= 150°C, θ = 200°C/W
OUT
IN
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)
T
JMAX
JA
DNC: DO NOT CONNECT
*CONNECT THE PINS TO DEVICE GND (PIN 4)
(Note 9)............................................................. 300°C
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
LTCVH
LTCVH
LTCVJ
LTCVJ
LTCQV
LTCQV
LTCVK
LTCVK
LTCVM
LTCVM
LTCVN
LTCVN
LTCVP
PACKAGE DESCRIPTION
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
8-Lead Plastic MSOP
TEMPERATURE RANGE
LTC6652AHMS8-1.25#PBF
LTC6652BHMS8-1.25#PBF
LTC6652AHMS8-2.048#PBF
LTC6652BHMS8-2.048#PBF
LTC6652AHMS8-2.5#PBF
LTC6652BHMS8-2.5#PBF
LTC6652AHMS8-3#PBF
LTC6652BHMS8-3#PBF
LTC6652AHMS8-3.3#PBF
LTC6652BHMS8-3.3#PBF
LTC6652AHMS8-4.096#PBF
LTC6652BHMS8-4.096#PBF
LTC6652AHMS8-5#PBF
LTC6652BHMS8-5#PBF
LTC6652AHMS8-1.25#TRPBF
LTC6652BHMS8-1.25#TRPBF
LTC6652AHMS8-2.048#TRPBF
LTC6652BHMS8-2.048#TRPBF
LTC6652AHMS8-2.5#TRPBF
LTC6652BHMS8-2.5#TRPBF
LTC6652AHMS8-3#TRPBF
LTC6652BHMS8-3#TRPBF
LTC6652AHMS8-3.3#TRPBF
LTC6652BHMS8-3.3#TRPBF
LTC6652AHMS8-4.096#TRPBF
LTC6652BHMS8-4.096#TRPBF
LTC6652AHMS8-5#TRPBF
LTC6652BHMS8-5#TRPBF
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
LTCVP
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
INITIAL ACCURACY
TEMPERATURE COEFFICIENT
PART NUMBER**
1.250
0.05ꢀ
0.1ꢀ
5ppm/°C
10ppm/°C
LTC6652AHMS8-1.25
LTC6652BHMS8-1.25
2.048
2.500
3.000
3.300
4.096
5.000
0.05ꢀ
0.1ꢀ
0.05ꢀ
0.1ꢀ
0.05ꢀ
0.1ꢀ
0.05ꢀ
0.1ꢀ
0.05ꢀ
0.1ꢀ
0.05ꢀ
0.1ꢀ
5ppm/°C
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
10ppm/°C
5ppm/°C
10ppm/°C
5ppm/°C
10ppm/°C
5ppm/°C
10ppm/°C
5ppm/°C
10ppm/°C
5ppm/°C
10ppm/°C
**See Order Information section for complete part number listing.
6652fb
2
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 + 0ꢀ5V% unless otherwise notedꢀ
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Output Voltage
LTC6652A
LTC6652B
–0.05
–0.1
0.05
0.1
ꢀ
ꢀ
l
l
Output Voltage Temperature Coefficient
(Note 3)
LTC6652A
LTC6652B
2
4
5
10
ppm/°C
ppm/°C
Line Regulation
V
+ 0.5V ≤ V ≤ 13.2V, SHDN = V
IN
2
50
80
ppm/V
ppm/V
OUT
IN
l
l
Load Regulation (Note 4)
I
= 5mA, LTC6652-1.25, LTC6652-2.048,
20
75
200
ppm/mA
ppm/mA
SOURCE
LTC6652-2.5, LTC6652-3, LTC6652-3.3, LTC6652-
4.096, LTC6652-5
I
= 1mA, LTC6652-1.25, LTC6652-2.048
80
50
250
600
ppm/mA
ppm/mA
SINK
l
l
I
= 5mA, LTC6652-2.5, LTC6652-3,
150
450
ppm/mA
ppm/mA
SINK
LTC6652-3.3, LTC6652-4.096, LTC6652-5
= 5mA, V Error ≤ 0.1ꢀ
Minimum Operating Voltage (Note 5)
I
SOURCE
OUT
l
l
LTC6652-1.25, LTC6652-2.048
LTC6652-2.5, LTC6652-3, LTC6652-3.3,
LTC6652-4.096, LTC6652-5
2.7
OUT
V
V
V
+ 0.3V
Output Short-Circuit Current
Short V
Short V
to GND
16
16
mA
mA
OUT
OUT
to V
IN
l
l
Shutdown Pin (SHDN)
Logic High Input Voltage
Logic High Input Current
2
V
μA
0.1
1
l
l
Logic Low Input Voltage
Logic Low Input Current
0.8
1
V
μA
0.1
Supply Current
No Load
350
μA
μA
l
l
560
2
Shutdown Current
SHDN Tied to GND
0.1
μA
Output Voltage Noise (Note 6)
0.1Hz ≤ f ≤ 10Hz
LTC6652-1.25
2.4
2.1
2.2
2.3
2.8
3
ppm
ppm
ppm
ppm
ppm
P-P
P-P
P-P
P-P
P-P
LTC6652-2.048, LTC6652-2.5, LTC6652-3
LTC6652-3.3
LTC6652-4.096
LTC6652-5
10Hz ≤ f ≤ 1kHz
ppm
RMS
Turn-On Time
0.1ꢀ Settling, C
= 0
100
60
μs
LOAD
Long Term Drift of Output Voltage (Note 7)
Hysteresis (Note 8)
ppm/√khr
Δ = –40°C to 125°C
T
105
ppm
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.
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 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
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
LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ
Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ
1ꢀ25V Output Voltage
Temperature Drift
1ꢀ25V Line Regulation
1ꢀ25V Load Regulation (Sourcing)
1.2510
1.2505
1.2500
1.2495
1.2490
1.2506
1.2504
1.2502
1.2500
0
–50
3 TYPICAL PARTS
–40oC
125°C
25oC
–100
–150
–200
–250
125oC
25°C
1.2498
1.2496
1.2494
–40°C
10
80
TEMPERATURE (°C)
–80
–40
0
40
120
160
8
12
14
0
2
4
6
0.1
1
10
INPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
6652 G17
6652 G18
6652 G19
1ꢀ25V Low Frequency 0ꢀ1Hz to
10Hz Transient Noise
1ꢀ25V Output Voltage Noise
Spectrum
1ꢀ25V Load Regulation (Sinking)
400
350
300
250
200
150
100
50
400
300
200
100
0
125°C
25°C
–40°C
0
0.1
1
10
TIME (1 SECOND/DIV)
0.01
0.1
1
10
OUTPUT CURRENT (mA)
FREQUENCY (kHz)
6652 G22
6652 G20
6652 G21
1ꢀ25 Sinking Current Without
Output Capacitor
1ꢀ25 Sinking Current with Output
Capacitor
1ꢀ25V Stability with Output
Capacitance
10μF
1μF
1mA
0mA
1mA
0mA
I
I
OUT
OUT
0.1μF
10nF
V
V
OUT
500mV/DIV
REGION OF
MARGINAL
STABILITY
OUT
500mV/DIV
1nF
100pF
6652 G23
6652 G24
500μs/DIV
500μs/DIV
C
= 0μF
C
= 1μF
OUT
OUT
NO CAP
–5
–1
0
5
LOAD CURRENT (mA)
6652 G16
6652fb
4
LTC6652
TYPICAL PERFORMANCE CHARACTERISTICS
Characteristic curves are similar for most
LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ
Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ
2ꢀ5V Output Voltage
Temperature Drift
2ꢀ5V Line Regulation
2ꢀ5V Load Regulation (Sourcing)
0
–20
2.5010
2.5005
2.5000
2.4995
2.4990
2.4985
2.5010
2.5005
2.5000
2.4995
3 TYPICAL PARTS
–40°C
–40
–60
125°C
25°C
25°C
–80
125°C
–100
–120
–140
–160
–180
–200
–40°C
2.4990
2.4985
2.4980
50
0.1
1
10
–50 –25
0
25
75 100 125 150
8
12
14
0
2
4
6
10
OUTPUT CURRENT (mA)
TEMPERATURE (°C)
INPUT VOLTAGE (V)
6652 G01
6652 G03
6652 G02
2ꢀ5V Supply Current
vs Input Voltage
2ꢀ5V Shutdown Current
vs Input Voltage
2ꢀ5V Load Regulation (Sinking)
1000
900
800
700
600
500
400
300
200
100
0
700
600
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
500
400
125°C
25°C
125°C
125°C
25°C
200
100
0
–40°C
25°C
–40°C
–40°C
0
4
6
8
10
12
14
0.1
1
10
2
0
4
6
8
10
12
14
2
INPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
INPUT VOLTAGE (V)
6652 G05
6652 G04
6652 G06
2ꢀ5V Minimum VIN-VOUT
Differential (Sourcing)
2ꢀ5V Minimum VOUT-VIN
Differential (Sinking)
10
10
1
1
25°C
0.1
0.01
25°C
125°C, –40°C
125°C
–40°C
0.1
0.001
0.01
0.1
1
0.001
0.01
0.1
1
OUTPUT-INPUT VOLTAGE (V)
INPUT-OUTPUT VOLTAGE (V)
6652 G10
6652 G09
6652fb
5
LTC6652
TYPICAL PERFORMANCE CHARACTERISTICS
Characteristic curves are similar for most
LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ
Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ
2ꢀ5V Low Frequency 0ꢀ1Hz to
10Hz Transient Noise
2ꢀ5V Output Voltage Noise
Spectrum
600
500
400
300
200
100
0
TIME (1 SECOND/DIV)
0.01
0.1
1
10
FREQUENCY (kHz)
6652 G12
6652 G11
Stability with Output Capacitance
(LTC6652-2ꢀ5% LTC6652-3%
LTC6652-3ꢀ3% LTC6652-4ꢀ906%
LTC6652-5)
Typical VOUT Distribution for
LTC6652-2ꢀ5
180
160
140
120
80
10μF
1μF
1004 UNITS
LTC6652A LIMITS
0.1μF
10nF
REGION OF
MARGINAL STABILITY
60
1nF
100pF
40
20
0
NO CAP
2.4985
2.4995
2.5005
2.5015
–5
0
5
OUTPUT VOLTAGE (V)
LOAD CURRENT (mA)
6652 G15
6652 G14
6652fb
6
LTC6652
TYPICAL PERFORMANCE CHARACTERISTICS
Characteristic curves are similar for most
LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ
Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ
5V Output Voltage
Temperature Drift
5V Supply Current
vs Input Voltage
5V Line Regulation
5.005
5.003
5.000
4.998
4.995
5.002
5.001
5.000
4.999
4.998
1000
900
800
700
600
500
400
300
200
100
0
3 TYPICAL PARTS
25°C
125°C
–40°C
125°C
25°C
–40°C
50
0
2
4
6
8
10
12
14
–50 –25
0
25
75 100 125 150
0
4
6
8
10
12
14
2
TEMPERATURE (°C)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
6652 G25
6652 G26
6652 G27
5V Shutdown Current
vs Input Voltage
5V Minimum VIN to VOUT
Differential (Sourcing)
5V Low Frequency 0ꢀ1Hz to 10Hz
Transient Noise
10
1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
125°C
25°C
0.1
0.01
–40°C
–40°C
125°C
25°C
10
12
INPUT VOLTAGE (V)
0.001
0.01
0.1
1
0
4
6
8
14
TIME (1 SECOND/DIV)
2
INPUT-OUTPUT VOLTAGE (V)
6652 G30
6652 G31
6652 G29
5V Start-Up Response Without
Output Capacitor
5V Start-Up Response with Output
Capacitor
5V Output Voltage Noise Spectrum
1000
800
600
400
200
0
V
V
IN
IN
2V/DIV
2V/DIV
V
V
OUT
2V/DIV
OUT
2V/DIV
6652 G33
6652 G34
100μs/DIV
100μs/DIV
C
= 0μF
C
= 1μF
OUT
OUT
0.01
0.1
1
10
FREQUENCY (kHz)
6652 G32
6652fb
7
LTC6652
TYPICAL PERFORMANCE CHARACTERISTICS
Characteristic curves are similar for most
LTC6652sꢀ Curves from the LTC6652-1ꢀ25% LTC6652-2ꢀ5 and the LTC6652-5 represent the extremes and typical of the voltage optionsꢀ
Characteristic curves for other output voltages fall between these curves and can be estimated based on their outputꢀ
Power Supply Rejection Ratio
vs Frequency
SHDN Input Voltage Thresholds
Output Impedance vs Frequency
vs VIN
100
0
–10
–20
–30
2.5
2.0
1.5
1.0
0.5
0
C
OUT
= 0μF
C
OUT
= 0μF
V
TH(UP)
10
1
C
OUT
= 1μF
–40
–50
V
TH(DN)
C
OUT
= 1μF
C
OUT
= 10μF
–60
–70
C
OUT
= 10μF
–80
–90
0.1
–100
8
12
14
0.01
0.1
1
10
100
1000
0.01
0.1
1
10
100
2
4
6
10
FREQUENCY (kHz)
FREQUENCY (kHz)
V
IN
(V)
6652 G13
6652 G08
6652 G07
PIN FUNCTIONS
DNC (Pin 1): Do Not Connect.
GND (Pin 4): Device Ground.
(Pin 6): Output Voltage. An output capacitor is not
required.Forsomeapplications,acapacitorbetween0.1μF
to 10μF can be beneficial. See the graphs in the Typical
Performance Characteristics section for further details.
V (Pin 2): Power Supply. The minimum supply input is
V
OUT
IN
OUT
V
+300mVor2.7V;whicheverishigher.Themaximum
supply is 13.2V. Bypassing V with a 0.1μF capacitor to
GND will improve PSRR.
IN
SHDN (Pin 3): Shutdown Input. This active low input
GND (Pins 5%7%8): Internal function. Ground these pins.
powers down the device to <2μA. For normal operation
tie this pin to V .
IN
6652fb
8
LTC6652
BLOCK DIAGRAM
V
IN
2
+
–
V
OUT
SHDN
BANDGAP
3
6
GND
4
6652 BD
APPLICATIONS INFORMATION
Bypass and Load Capacitors
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.
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
acapacitiveload. Forapplicationswhereanoutputcapaci-
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
anyloadcurrentareacceptable. Forloadsthatsinkcurrent
orlightloadsthatsourcecurrent,a0.1μFto10μFcapacitor
has stable operation. For heavier loads that source current
a 0.5μF to 10μF capacitor range is recommended.
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.
100Ω
2, 3
6
V
IN
LTC6652-2.5
3V
C
IN
C
The transient response for a 0.5V step on V with and
OUT
1μF
IN
0.5V
V
GEN
0.1μF
without an output capacitor is shown in Figures 2 and 3,
4, 5, 7, 8
6652 F01
respectively.
Figure 1ꢀ Transient Load Test Circuit
6652fb
9
LTC6652
APPLICATIONS INFORMATION
3.5V
5mA
0mA
V
IN
I
3V
OUT
V
OUT
500mV/DIV
V
OUT
200mV/DIV
6652 F05
6652 F02
C
OUT
= 0μF
250μs/DIV
C
= 0μF
500μs/DIV
OUT
Figure 2ꢀ Transient Response Without Output Capacitor
Figure 5ꢀ LTC6652-2ꢀ5 Sinking
Current Without Output Capacitor
0mA
3.5V
I
OUT
V
IN
–5mA
3V
V
OUT
500mV/DIV
V
OUT
200mV/DIV
6652 F03
6652 F06
C
= 1μF
500μs/DIV
C
OUT
= 1μF
250μs/DIV
OUT
Figure 6ꢀ LTC6652-2ꢀ5 Sourcing Current
with Output Capacitor
Figure 3ꢀ Transient Response with 1μF Output Capacitor
5mA
0mA
I
I
OUT
OUT
0mA
–5mA
V
OUT
V
OUT
50mV/DIV
200mV/DIV
6652 F07
6652 F04
C
OUT
= 1μF
250μs/DIV
C
= 0μF
250μs/DIV
OUT
Figure 7ꢀ LTC6652-2ꢀ5 Sinking
Current with Output Capacitor
Figure 4ꢀ LTC6652-2ꢀ5 Sourcing
Current Without Output Capacitor
6652fb
10
LTC6652
APPLICATIONS INFORMATION
2.8V b V b 13.2V
IN
C1
1μF
R1
20k
V
IN
2V/DIV
V
IN
LTC6652-2.5
SHDN
V
OUT
V
OUT
GND
V
TO μC
6652 F10
OUT
C2
1μF
2N7002
1V/DIV
Figure 10ꢀ Open-Drain Shutdown Circuit
6652 F08
C
= 0μF
100μs/DIV
OUT
Figure 8ꢀ Start-Up Response Without Output Capacitor
SHDN
1V/DIV
V
IN
2V/DIV
V
OUT
1V/DIV
V
OUT
1V/DIV
6652 F11
I
= 5mA
1ms/DIV
LOAD
6652 F09
Figure 11ꢀ Shutdown Response with 5mA Load
C
= 1μF
100μs/DIV
OUT
Figure 9ꢀ Start-Up Response with 1μF Output Capacitor
The trip thresholds on SHDN have some dependence
on the voltage applied to V as shown in the Typical
IN
InFigure8,ripplemomentarilyappearsjustaftertheleading
edge of powering on. This brief one time event is caused
bycalibrationcircuitryduringinitialization.Whenanoutput
capacitor is used, the ripple is virtually undetectable as
shown in Figure 9.
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
Shutdown Mode
Long-term drift cannot be extrapolated from acceler-
atedhightemperaturetestingꢀThiserroneoustechnique
gives drift numbers that are wildly optimisticꢀ The only
way long-term drift can be determined is to measure it
overthetimeintervalofinterestꢀTheLTC6652long-term
drift data was collected on more than 100 parts that were
solderedintoPCboardssimilartoa“realworld”application.
The boards were then placed into a constant temperature
ShutdownmodeisenabledbytyingSHDNlowwhichplaces
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 V and
IN
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.
oven with T = 35°C, their outputs were scanned regularly
A
and measured with an 8.5 digit DVM. Long-term drift is
shown below in Figure 12.
6652fb
11
LTC6652
APPLICATIONS INFORMATION
80
35
30
25
20
15
10
5
LTC6652-2.5 MS8 PACKAGE
3 TYPICAL PARTS
125°C TO 25°C
–40°C TO 25°C
T
= 35oC
60
40
A
20
0
–20
–40
0
0
300
600
900
1200
1500
–250
–150
–50
50
150
HOURS
DISTRIBUTION (ppm)
6652 F12
6652 F13
Figure 12ꢀ Long Term Drift
Figure 13ꢀ 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,
Thedifferentexpansionandcontractionratesofthemateri-
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 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 0.003ꢀ as shown in Figure
15. While there can be up to 0.016ꢀ of output voltage
shift, the overall drift of the LTC6652 after IR reflow does
not vary significantly.
i.e., for the LT6652-2.5, P = 10.7V • 5.5mA = 58.85mW.
D
ThethermalresistanceoftheMS8packageis200°C/Wand
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.
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.
Power Dissipation
Power dissipation in the LTC6652 is dependent on V ,
IN
load current, and package. The LTC6652 package has
a thermal resistance, or θ , of 200°C/W. A curve that
JA
The capacitors should be mounted close to the package.
illustrates allowed power dissipation vs temperature for
The GND and V
traces should be as short as possible
this package is shown in Figure 16.
OUT
to minimize I • R drops. Excessive trace resistance directly
impacts load regulation.
The power dissipation of the LTC6652-2.5V as a function
of input voltage is shown in Figure 17. The top curve
showspowerdissipationwitha5mAloadandthebottom
6652fb
12
LTC6652
APPLICATIONS INFORMATION
curve shows power dissipation with no load.
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.
When operated within its specified limits of V = 13.2V
IN
andsourcing5mA,theLTC6652-2.5consumesjustunder
60mW at room temperature. At 125°C the quiescent cur-
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
300
380s
T
= 260°C
P
RAMP
DOWN
T
= 217°C
L
225
150
75
T
= 200°C
S(MAX)
t
T
= 190°C
P
S
30s
T = 150°C
t
L
RAMP TO
150°C
130s
40s
120s
4
0
0
20
40
60
140
0
2
6
8
10
80 100 120
MINUTES
TEMPERATURE (°C)
6652 F16
6652 F14
Figure 14ꢀ Lead-Free Reflow Profile
Figure 16ꢀ Maximum Recommended Dissipation for LTC6652
10
0.06
T
= 25°C
A
0.05
0.04
0.03
0.02
0.01
0
8
6
4
2
0
5mA LOAD
NO LOAD
–0.014 –0.006
0.002
0.010
0.018
2
4
6
8
14
10
12
OUTPUT VOLTAGE SHIFT DUE TO IR REFLOW (ꢀ)
V
IN
(V)
6652 F17
6652 F15
Figure 17ꢀ Typical Power Dissipation of the LTC6652
Figure 15ꢀ Output Voltage Shift Due to IR Reflow
6652fb
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
R1
MMBT5551
V
OUT
V
V
OUT
LTC6652-2.5
GND
IN
V
IN
SHDN
SHDN
C1
0.1μF
BZX84C18
C2
OPTIONAL
6652 TA02
V
V
LTC6652-2.5
GND
OUT
OUT
BZX84C18
C2
OPTIONAL
C1
0.1μF
6652 TA03
Negative Rail Circuit
Boosted Output Current
+
V
r (V
+ 1.8V)
OUT
R1
2207
C1
1μF
2, 3, 6
LTC6652-2.5
2N2905
V
SHDN
IN
6652 TA06
4, 5, 7, 8
100Ω
–3.5V
V
OUT
–2.5V
1μF
V
OUT
LTC6652-2.5
GND
C2
1μF
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)
0.52
(.0205)
REF
0.65
(.0256)
BSC
0.42 ± 0.038
(.0165 ± .0015)
TYP
8
7 6 5
RECOMMENDED SOLDER PAD LAYOUT
3.00 ± 0.102
(.118 ± .004)
(NOTE 4)
4.90 ± 0.152
(.193 ± .006)
DETAIL “A”
0.254
(.010)
0° – 6° TYP
GAUGE PLANE
1
2
3
4
0.53 ± 0.152
(.021 ± .006)
1.10
(.043)
MAX
0.86
(.034)
REF
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.22 – 0.38
0.1016 ± 0.0508
(.009 – .015)
(.004 ± .002)
0.65
(.0256)
BSC
TYP
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 representa-
tion 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
REF
DATA
VDAC
V
CC
GND
V
IN
R1
50k
V
OUT
LTC6652
REF
A/D
LTC1605
SHDN
V1
16
C1
0.1μF
V2
V3
V4
D
OUT
C2
C
OUT
10μF
1μF
GND
GND
6652 TA05
RELATED PARTS
PART NUMBER DESCRIPTION
COMMENTS
LT1460
LT1461
LT1790
LT6650
LT6660
Micropower Series References
Micropower Series Low Dropout
Micropower Precision Series References
0.075ꢀ Max, 10ppm/°C Max, 20mA Output Current
0.04ꢀ Max, 3ppm/°C Max, 50mA Output Current
0.05ꢀ Max, 10ppm/°C Max, 60μA Supply, SOT23 Package
0.5ꢀ Max, 5.6μA Supply, SOT23 Package
Micropower Reference with Buffer Amplifier
Tiny Micropower Series Reference
0.2ꢀ Max, 20ppm/°C Max, 20mA Output Current, 2mm × 2mm DFN
6652fb
LT 1208 REV B • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
© LINEAR TECHNOLOGY CORPORATION 2007
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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