LM4140BCM-2.5 [NSC]
High Precision Low Noise Low Dropout Voltage; 高精密，低噪声低压差
| 型号： | LM4140BCM-2.5 |
| 厂家： | 
National Semiconductor |
| 描述： | High Precision Low Noise Low Dropout Voltage |
| 文件： | 总15页 (文件大小：442K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
July 2000
LM4140
High Precision Low Noise Low Dropout Voltage
Reference
General Description
The LM4140 series of precision references are designed to
combine high accuracy, low drift and noise with low power
dissipation in a small package.
Features
n High initial accuracy: 0.1%
n Ultra low noise
n Low Temperature Coefficient: 3 ppm/˚C (A grade)
n Low voltage operation: 1.8V
n SO-8 package
The LM4140 is the industry’s first reference with output volt-
age options lower than the bandgap voltage.
@
The key to the advance performance of the LM4140 is the
use of EEPROM registers and CMOS DACs for temperature
coefficient curvature correction and trimming of the output
voltage accuracy of the device during the final production
testing.
n Low dropout voltage: 20 mV (typ) 1mA
n Supply Current: 230 µA (typ), ≤ 1 µA disable mode
n Enable pin
n Output voltage options: 1.024V, 1.250V, 2.048V, 2.500V,
and 4.096V
The major advantage of this method is the much higher reso-
lution available with DACs than is available economically
with most methods utilized by other bandgap references.
n Custom voltages from 0.5V to 4.5V
n Temperature range (0˚C to 70˚C)
The low input and dropout voltage, low supply current and
output drive capability of the LM4140 makes this product an
ideal choice for battery powered and portable applications.
Applications Summary
n Portable, battery powered equipment
n Instrumentation and test equipment
n Automotive
n Industrial process control
n Data acquisition systems
n Medical equipment
The LM4140 is available in three grades (A, B, C) with 0.1%
initial accuracy and 3, 6 and 10 ppm/˚C temperature coeffi-
cients. For even lower Tempco, contact National Semicon-
ductor.
The device performance is specified over the temperature
range (0˚C to +70˚C) and is available in compact 8-pin SO
package.
n Precision scales
n Servo systems
n Battery charging
For other output voltage options from 0.5V to 4.5V, con-
tact National Semiconductor.
Typical Application
Typical Temperature Coefficient
(Sample of 5 Parts)
DS101079-1
C
, Output bypass capacitor. See text for selection detail.
OUT
DS101079-23
Refer to the Ordering Information Table in this Data Sheet for Specific Part
Number
© 2000 National Semiconductor Corporation
DS101079
www.national.com
Ordering Information Temperature Range (0˚C to 70˚C)
Initial Output Voltage Accuracy
LM4140 Supplied as 95 Units,
LM4140 Supplied as 2500
Units, Tape and Reel
@
25˚C
Tape and Reel
and Temperature Coefficient
LM4140ACM-1.0
LM4140ACM-1.2
LM4140ACM-2.0
LM4140ACM-2.5
LM4140ACM-4.1
LM4140BCM-1.0
LM4140BCM-1.2
LM4140BCM-2.0
LM4140BCM-2.5
LM4140BCM-4.1
LM4140CCM-1.0
LM4140CCM-1.2
LM4140CCM-2.0
LM4140CCM-2.5
LM4140CCM-4.1
LM4140ACMX-1.0
LM4140ACMX-1.2
LM4140ACMX-2.0
LM4140ACMX-2.5
LM4140ACMX-4.1
LM4140BCMX-1.0
LM4140BCMX-1.2
LM4140BCMX-2.0
LM4140BCMX-2.5
LM4140BCMX-4.1
LM4140CCMX-1.0
LM4140CCMX-1.2
LM4140CCMX-2.0
LM4140CCMX-2.5
LM4140CCMX-4.1
0.1%, 3 ppm/˚C max (A grade)
0.1%, 6 ppm/˚C max (B grade)
0.1%, 10 ppm/˚C max (C grade)
Connection Diagram
8-Lead Surface Mount (M)
DS101079-2
Top View
See NS Package Number M08A
Pin Functions
Vref (Pin 6):
Reference Output. Capable of sourcing up to 8mA.
Positive Supply.
Input (Pin 2):
Ground (Pins 1, 4, 7, 8):
Negative Supply or Ground Connection. These pins must be
connected to ground.
Enable (Pin 3):
NC (Pin 5):
Pulled to input for normal operation. Forcing this pin to ground will
turn-off the output.
This pin must be left open.
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2
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Lead Temperature:
Soldering, (10 sec.)
+260˚C
Operating Range (Note 1)
Maximum Voltage on any Input pin
Output Short-Circuit Duration
−0.3V to 5.6V
Indefinite
Storage Temperature Range
Ambient Temperature Range
Junction Temperature Range
−65˚C to +150˚C
0˚C to 70˚C
Power Dissipation (TA = 25˚C)
(Note 2)
0˚C to 80˚C
345mW
ESD Susceptibility (Note 3)
Human Body Model
Machine Model
2 kV
200V
LM4140
Electrical Charateristics
Unless otherwise specified, VIN = 3.0V for the LM4140-1.024 and LM4140-1.250, VIN = 5.0V for all other voltage options, VEN
= VIN. COUT = 1µF (Note 4), ILOAD = 1mA, TA = TJ = 25˚C. Limits with standard typeface are for TA = 25˚C, and limits in
boldface type apply over 0˚C to 70˚C temperature range.
Min
(Note 6)
Typ
(Note 5)
Max
(Note 6)
Symbol
Parameter
Conditions
Units
Output Voltage Initial
Accuracy (Note 7)
LM4140B-1.024
LM4140B-1.250
LM4140B-2.048
LM4140B-2.500
LM4140B-4.096
±
±
0.1
0.1
VREF
%
LM4140C-1.024
LM4140C-1.250
LM4140C-2.048
LM4140C-2.500
LM4140C-4.096
TCVREF/˚C
Temperature Coefficient:
A Grade
B Grade
0˚C ≤ TA ≤ + 70˚C
ppm/˚C
3
6
10
C Grade
Line Regulation
1.024V and 1.250V options
1.8V ≤ VIN ≤ 5.5V
50
20
300
∆VREF/∆VIN
ppm/V
350
All other voltage options
Vref + 200mV ≤ VIN
≤
200
5.5V
250
Load Regulation
1 mA ≤ ILOAD ≤ 8mA
All other voltage options
1
5
20
150
35
∆VREF/∆ILOAD
ppm/mA
4.096V Option
150
∆VREF
∆VREF
Long-Term Stability
1000 Hrs
60
20
ppm
ppm
Thermal Hysteresis (Note
8)
0˚C ≤ TA ≤ + 70˚C
3
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LM4140
Electrical Charateristics (Continued)
Unless otherwise specified, VIN = 3.0V for the LM4140-1.024 and LM4140-1.250, VIN = 5.0V for all other voltage options, VEN
= VIN. COUT = 1µF (Note 4), ILOAD = 1mA, TA = TJ = 25˚C. Limits with standard typeface are for TA = 25˚C, and limits in
boldface type apply over 0˚C to 70˚C temperature range.
Min
(Note 6)
Typ
(Note 5)
Max
(Note 6)
Symbol
Parameter
LM4140-1.024,
Conditions
Units
Operating
Voltage
IL = 1 mA to 8 mA
1.8
5.5
V
LM4140-1.250
Dropout Voltage (Note 9)
LM4140-2.048,
LM4140-2.500
IL = 1 mA
20
160
20
40
45
IL = 8 mA
235
400
VIN-VREF
mV
LM4140-4.096
IL = 1 mA
40
45
IL = 8 mA
195
2.2
270
490
VN
Output Noise Voltage
(Note 10)
0.1 Hz to 10 Hz
ILOAD = 0 mA
µVPP
IS(ON)
Supply Current
All other voltage options
230
265
.01
2
320
375
350
400
1
µA
4.096V Option
<
IS(OFF)
VH
Supply Current
VEnable 0.4V
µA
V
Logic High Input Voltage
Logic High Input Current
Logic Low Input Voltage
Logic Low Input Current
Short Circuit Current
0.8VIN
IH
nA
V
VL
0.4
IL
1
nA
mA
ISC
8.5
20
35
40
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is in-
tended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see Electrical Characteristics. The guar-
anteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 2: Without PCB copper enhancements. The maximum power dissipation must be de-rated at elevated temperatures and is limited by T
(maximum junction
JMAX
temperature), θ
(junction to ambient thermal resistance) and T (ambient temperature). The maximum power dissipation at any temperature is: PDiss
= (T
MAX JMAX
J-A
A
− T )/θ
up to the value listed in the Absolute Maximum Ratings. The θ
for the SO-8 package is 160˚C/W.
J-A
A
J-A
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged di-
rectly into each pin.
Note 4: For proper operation, a 1µF capacitor is required between the output pin and the GND pin of the device. (See Application Section for details)
Note 5: Typical numbers are at 25˚C and represent the most likely parametric norm.
Note 6: Limits are 100% production tested at 25˚C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control
(SQC) methods. The limits are used to calculate National’s Average Outgoing Quality Level (AOQL).
Note 7: High temperature and mechanical stress associated with PCB assembly can have significant impact on the initial accuracy of the LM4140 and may create
significant shifts in V
. See Application Hints section regarding accuracy and PCB layout consideration.
REF
Note 8: Thermal hysteresis is defined as the changes in +25˚C output voltage before and after the cycling of the device from 0˚C to 70˚C.
Note 9: Dropout voltage is defined as the minimum input to output differential voltage at which the output voltage drops by 0.5% below the value measured with V
IN
= 3.0V for the LM4140-1.024 and LM4140-1.250, V = 5.0V for all other voltage options.
IN
Note 10: The output noise is based on 1.024V option. Output noise is linearly proportional to V
.
REF
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4
LM4140 Typical Performance Characteristics Unless otherwise specified, TA = 25˚C, No Load,
COUT = 1µF, VIN = 3.0V for LM4140-1.024 and LM4140-1.250, and 5V for all other voltage options. VIN = VEN
.
Power Up/Down Ground Current Enable Response
DS101079-5
DS101079-6
*
The 1µF output capacitor is actively discharged to ground. See ON/OFF Operation section for more details.
Line Transient Response
Load Transient Response
DS101079-8
DS101079-7
5
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LM4140 Typical Performance Characteristics Unless otherwise specified, TA = 25˚C, No Load,
COUT = 1µF, VIN = 3.0V for LM4140-1.024 and LM4140-1.250, and 5V for all other voltage options. VIN = VEN. (Continued)
Output Impedance
Power Supply Rejection Ratio
DS101079-10
DS101079-9
Dropout Voltage vs Load Current
Output Voltage Change vs Sink Current (ISINK)
DS101079-11
DS101079-12
Note: 1.024V and 1.250V options require 1.8V supply.
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6
LM4140 Typical Performance Characteristics Unless otherwise specified, TA = 25˚C, No Load,
COUT = 1µF, VIN = 3.0V for LM4140-1.024 and LM4140-1.250, and 5V for all other voltage options. VIN = VEN. (Continued)
Total Current (IS(OFF)) vs Supply Voltage
Total Current (IS(ON)) vs Supply Voltage
DS101079-13
DS101079-14
Spectral Noise Density (0.1Hz to 10Hz)
Spectral Noise Density (10Hz to 100kHz)
DS101079-31
DS101079-32
Ground Current vs Load Current
Long Term Drift
DS101079-38
DS101079-39
7
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LM4140 Typical Performance Characteristics Unless otherwise specified, TA = 25˚C, No Load,
COUT = 1µF, VIN = 3.0V for LM4140-1.024 and LM4140-1.250, and 5V for all other voltage options. VIN = VEN. (Continued)
Load Regulation vs Temperature
Output Voltage vs Load Current
DS101079-41
DS101079-40
Line Regulation vs Temperature
IQ vs Temperature
DS101079-42
DS101079-43
Short Circuit Current vs Temperature
Dropout Voltage vs Load Current (VOUT) = 2.0V
DS101079-44
DS101079-45
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8
Application Hints
Input Capacitors
Although not always required, an input capacitor is recom-
mended. A supply bypass capacitor on the input assures that
the reference is working from a source with low impedance,
which improves stability. A bypass capacitor can also im-
prove transient response by providing a reservoir of stored
energy that the reference can utilize in case where the load
current demand suddenly increases. The value used for CIN
may be used without limit. Refer to the typical application
section for examples of input capacitors.
Output Capacitors
The LM4140 requires a 1µF (nominally) output capacitor for
loop stability (compensation) as well as transient response.
During the sudden changes in load current demand, the out-
put capacitor must source or sink current during the time it
takes the control loop of the LM4140 to respond.
DS101079-30
FIGURE 3. 10 µF ESR Range
Tantalum Capacitors
This capacitor must be selected to meet the requirements of
minimum capacitance and equivalent series resistance
(ESR) range.
Surface-mountable solid tantalum capacitors offer a good
combination of small physical size for the capacitance value,
and ESR in the range needed for by the LM4140. The results
of testing the LM4140 stability with surface mount solid tan-
talum capacitors show good stability with values in the range
of 0.1µF. However, optimum performance is achieved with a
1µF capacitor.
In general, the capacitor value must be at least 0.2µF (over
the actual ambient operating temperature), and the ESR
must be within the range indicated in Figure 1, Figure 2 and
Figure 3.
Tantalum capacitors that have been verified as suitable for
use with the LM4140 are shown in Table 1.
TABLE 1. Surface-Mount Tantalum Capacitor Selection
Guide
1µF Surface-Mount Tantalums
Manufacturer
Kemet
Part Number
T491A105M010AS
NRU105N10
NEC
Siemens
Nichicon
Sprague
B45196-E3105-K
F931C105MA
293D105X0016A2T
DS101079-28
2.2µF Surface-Mount Tantalums
FIGURE 1. 0.22 µF ESR Range
Kemet
NEC
T491A225M010AS
NRU225M06
Siemens
Nichicon
Sprague
B45196/2.2/10/10
F930J225MA
293D225X0010A2T
Aluminum Electrolytic Capacitors
Although probably not a good choice for a production design,
because of relatively large physical size, an aluminium elec-
trolytic capacitor can be used in the design prototype for an
LM4140 reference. A 1µF capacitor meeting the ESR condi-
tions can be used. If the operating temperature drops below
0˚C, the reference may not remain stable, as the ESR of the
aluminium electrolytic capacitor will increase, and may ex-
ceed the limits indicated in the figures.
DS101079-29
Multilayer Ceramic Capacitors
FIGURE 2. 1 µF ESR Range
Surface-mountable multilayer ceramic capacitors may be an
attractive choice because of their relatively small physical
size and excellent RF characteristics.
9
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LM4140 input voltage. This high-level voltage may exceed
the LM4140 input voltage, but must remain within the Abso-
lute Maximum Rating for the enable pin.
Application Hints (Continued)
However, they sometimes have an ESR values lower than
the minimum required by the LM4140, and relatively large
capacitance change with temperature. The manufacturer’s
datasheet for the capacitor should be consulted before se-
lecting a value. Test results of LM4140 stability using multi-
layer ceramic capacitors show that a minimum of 0.2µF is
usually needed.
Output Accuracy
Like all references, either series or shunt, the after assembly
accuracy is made up of primarily three components: initial
accuracy itself, thermal hysteresis and effects of the PCB as-
sembly stress.
Multilayer ceramic capacitors that have been verified as suit-
able for use with the LM4140 are shown in Table 2.
LM4140 provides an excellent output initial accuracy of 0.1%
and temperature coefficient of 6ppm/˚C (B Grade).
For best accuracy and precision, the LM4140 junction tem-
perature should not exceed 70˚C.
TABLE 2. Surface-Mount Ceramic Capacitors Selection
Guide
The thermal hysteresis curve on this datasheet are perfor-
mance characteristics of three typical parts selected at ran-
dom from a sample of 40 parts.
2.2µF Surface-Mount Ceramic
Manufacturer
Tokin
Part Number
1E225ZY5U-C203
GRM42-6Y5V225Z16
Parts are mounted in a socket to minimize the effect of
PCB’s mechnical expansion and contraction. Readings are
taken at 25˚C following multiple temperature cycles to 0˚C
and 70˚C. The labels on the X axis of the graph indicates the
device temperature cycle prior to measurement at 25˚C.
Murata
4.7µF Surface-Mount Ceramic
Tokin
1E475ZY5U-C304
Reverse Current Path
The P-channel Pass transistor used in the LM4140 has an
inherent diode connected between the VIN and VREF pins
(see diagram below).
DS101079-3
Forcing the output to voltages higher than the input, or pull-
ing VIN below voltage stored on the output capacitor by more
than a Vbe, will forward bias this diode and current will flow
from the VREF terminal to VIN. No damage to the LM4140 will
occur under these conditions as long as the current flowing
into the output pin does not exceed 50mA.
DS101079-33
FIGURE 4. Typical Thermal Hysteresis
The mechanical stress due to the PCB’s mechanical and
thermal stress can cause an output voltage shift more than
the true thermal coefficient of the device. References in sur-
face mount packages are more susceptible to these stresses
because of the small amount of plastic molding which sup-
port the leads.
ON/OFF Operation
The LM4140 is designed to quickly reduce both VREF and IQ
to zero when turned-off. VREF is restored in less than 200µs
when turned-on. During the turn-off, the charge across the
output capacitor is discharged to ground through internal cir-
cuitry.
Following the recommendations on PCB Layout Consider-
ation section can minimize the mechanical stress on the de-
vice.
The LM4140 is turned-off by pulling the enable input low, and
turned-on by driving the input high. If this feature is not to be
used, the enable pin should be tied to the VIN to keep the ref-
erence on at all times (the enable pin must not be left float-
ing).
PCB Layout Consideration
The simplest ways to reduce the stress related shifts are:
1. Mounting the device near the edges or the corners of the
board where mechanical stress is at its minimum. The
center of the board generally has the highest mechani-
cal and thermal expansion stress.
To ensure proper operation, the signal source used to drive
the enable pin must be able to swing above and below the
specified high and low voltage thresholds which guarantee
an ON or OFF state (see Electrical Characteristics).
2. Mechanical isolation of the device by creating an island
by cutting a U shape slot on the PCB for mounting the
device. This approach would also provide some thermal
isolation from the rest of the circuit.
The ON/OFF signal may come from either a totem-pole out-
put, or an open-collector output with pull-up resistor to the
Figure 5 is a recommended printed board layout with a slot
cut on three sides of the circuit layout to serve as a strain
relief.
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10
Application Hints (Continued)
DS101079-34
DS101079-35
FIGURE 5. Suggested PCB Layout with Slot
11
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Typical Application Circuits
Boosted Output Current
Boosted Ouput Current with Current Limiter
DS101079-15
DS101079-22
Complimentary Outputs
Voltage Reference with Force and Sense Output
DS101079-20
DS101079-19
*
Low Noise Op Amp such as OP-27
Precision Programmable Current Source
Precision DAC Reference
DS101079-36
DS101079-21
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12
Typical Application Circuits (Continued)
Strain Gauge Conditioner for 350Ω Bridge
DS101079-37
DS101079-26
FIGURE 6.
13
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Typical Application Circuits (Continued)
DS101079-27
FIGURE 7.
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14
SO-8 Package Type M
NS Package Number M08A
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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
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Corporation
Americas
Tel: 1-800-272-9959
Fax: 1-800-737-7018
Email: support@nsc.com
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National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
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