OBSOLETE
LM3814, LM3815
www.ti.com
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
LM3814/LM3815 Fast Current Gauge IC with Ultra Low Loss Sense Element and PWM
Output
Check for Samples: LM3814, LM3815
FEATURES
DESCRIPTION
•
•
The LM3814/LM3815 Current Gauges provide easy
to use precision current measurement with virtually
zero insertion loss (typically 0.004Ω). The LM3814 is
used for high-side sensing and the LM3815 is used
for low-side sensing.
1
2
•
•
•
•
•
No External Sense Element Eequired
PWM Output Indicates the Current Magnitude
and Direction
PWM Output Can be Interfaced with
Microprocessors
Precision ΔΣ Current-Sense Technique
Low Temperature Sensitivity
Internal Filtering Rejects False Trips
Internal Power-On-Reset (POR)
APPLICATIONS
•
•
•
•
Battery Charge/Discharge Gauge
Motion Control Diagnostics
Power Supply Load Monitoring and
Management
Resettable Smart Fuse
KEY SPECIFICATIONS
•
•
•
•
•
Ultra Low Insertion Loss (typical) 0.004 Ω
Supply Range 2 to 5.25 V
Accuracy at Room Temperature (includes
accuracy of the internal sense element)
(LM3814-1.0, LM3815-1.0) ±3.5 %
Low Quiescent Current in Shutdown Mode
(typical) 2.5 µA
Sampling Interval 6 msec
A Delta Sigma analog to digital converter is
incorporated to precisely measure the current and to
provide a current averaging function. Current is
averaged over 6 msec time periods in order to
provide immunity to current spikes. The ICs have a
pulse-width modulated (PWM) output which indicates
the current magnitude and direction. The shutdown
pin can be used to inhibit false triggering during startup, or to enter a low quiescent current mode.
The LM3814 and LM3815 are factory-set in two
different current options. The sense range is −1A to
+1A or −7A to +7A. The user specifies a particular
part number to match the current range for a given
application. The sampling interval for these parts is
6ms. If larger sampling interval is desired for better
accuracy, please refer to the data sheets for the part
numbers LM3812 and LM3813.
CONNECTION DIAGRAMS
Figure 1. Top View
LM3814 for High-Side Sensing
Figure 2. Top View
LM3815 for Low-Side Sensing
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 1999–2013, Texas Instruments Incorporated
OBSOLETE
LM3814, LM3815
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
www.ti.com
ORDERING INFORMATION
(1)
(2)
(3)
Order No. (1)
Sense
Range
Sampling
Interval (2)
Sensing Method
Package
Number (3)
Package Type
Supplied As:
LM3814M-1.0
±1A
6 ms
High-side
M08A
SO-8
95 units in Rails
LM3814MX-1.0
±1A
6 ms
High-side
M08A
SO-8
2.5k units on
Tape and Reel
LM3814M-7.0
±7A
6 ms
High-side
M08A
SO-8
95 units in Rails
LM3814MX-7.0
±7A
6 ms
High-side
M08A
SO-8
2.5k units on
Tape and Reel
LM3815M-1.0
±1A
6 ms
Low-side
M08A
SO-8
95 units in Rails
LM3815MX-1.0
±1A
6 ms
Low-side
M08A
SO-8
2.5k units on
Tape and Reel
LM3815M-7.0
±7A
6 ms
Low-side
M08A
SO-8
95 units in Rails
LM3815MX-7.0
±7A
6 ms
Low-side
M08A
SO-8
2.5k units on
Tape and Reel
Suffix M indicates that the part is available in Surface Mount package. Suffix X indicates that the part is available in 2.5k units on Tape
and Reel.
Current is sampled over a fixed interval. The average current during this interval is indicated by the duty cycle of the PWM output during
next interval.
The Package code M08A is internal to TI and indicates an 8-lead surface mount package, SO-8.
PIN DESCRIPTIONS (HIGH-SIDE, LM3814)
Pin
Name
Function
1
SENSE+, VDD
High side of internal current sense, also supply voltage.
2
SENSE−
Low side of internal current sense.
3
FLTR+
Filter input — provides anti-aliasing for delta sigma modulator.
4
FLTR−
Filter input.
5
SD
Shutdown pin. Connected to VDD through a pull up resistor for normal operation. When low, the
IC goes into a low current mode (typically 3 µA).
6
PWM
PWM output indicates the current magnitude and direction.
7
GND
Ground
8
GND
Ground
PIN DESCRIPTIONS (LOW-SIDE, LM3815)
Pin
2
Name
Function
1
SENSE+, GND
High side of internal current sense, also ground.
2
SENSE−
Low side of internal current sense.
3
FLTR+
Filter input – provides anti-aliasing for delta sigma modulator.
4
FLTR−
Filter input.
5
SD
Shutdown pin. Connected to VDD through a pull up resistor for normal operation. When low, the
IC goes into a low current mode (typically 3 µA).
6
PWM
PWM output indicates the current magnitude and direction.
7
GND
Ground
8
VDD
VDD (supply)
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
OBSOLETE
LM3814, LM3815
www.ti.com
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
ABSOLUTE MAXIMUM RATINGS (1) (2)
Absolute Maximum Supply Voltage
5.5V
(3)
Power Dissipation
ESD Susceptibility (4)
1.5 kV
Sense Current (peak, for 200 msec)
(5)
10A
Sink Current for PWM pin
1 mA
Voltage on Pin 5
5.25V
Maximum Junction Temperature
150°C
−65°C to +150°C
Storage Temperature
Lead Temperature (Soldering, 10 sec)
(1)
(2)
(3)
(4)
(5)
260°C
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but do not ensure specific performance limits. For ensured specifications and test
conditions, see Electrical Characteristics. The ensured specifications apply only for the test conditions listed. Some performance
characteristics may degrade when the device is not operated under the listed test conditions.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and
specifications.
At elevated temperatures, devices must be derated based on package thermal resistance. The device in the surface-mount package
must be derated at θJA= 150°C/W (typically), junction-to-ambient.
The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.
The absolute maximum peak and continuous currents specified are not tested. These specifications are dependent on the θJA, which is
150°C/W for the SO8 package.
OPERATING RATINGS (1)
Input Voltage
2.0V to 5.25V
Sense Current (continuous) (2)
7A
Junction Temperature Range
−40°C to +125°C
(1)
(2)
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but do not ensure specific performance limits. For ensured specifications and test
conditions, see Electrical Characteristics. The ensured specifications apply only for the test conditions listed. Some performance
characteristics may degrade when the device is not operated under the listed test conditions.
The absolute maximum peak and continuous currents specified are not tested. These specifications are dependent on the θJA, which is
150°C/W for the SO8 package.
ELECTRICAL CHARACTERISTICS LM3814-1.0, LM3815-1.0
VDD = 5.0V for the following specifications. Supply bypass capacitor is 1µF and filter capacitor is 0.1µF.
Symbol
IACC
en
(1)
(2)
(3)
Parameter
Average Current Accuracy
Conditions
(3)
at 0.9A current
Effective Output Noise (rms)
Typ (1)
Limit (2)
Units
0.868 / 0.850
A (min)
0.932 / 0.950
A (max)
0.9
12
A
mA
Typical numbers are at 25°C and represent the most likely parametric norm. Specifications in standard type face are for TJ= 25°C and
those with boldface type apply over full operating temperature ranges.
Limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlation using Statistical
Quality Control (SQC) methods. The limits are used to calculate TI's Averaging Outgoing Quality Level (AOQL).
There is a variation in accuracy over time due to thermal effects. Please refer to the PWM OUTPUT AND CURRENT ACCURACY
section for more information.
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
3
OBSOLETE
LM3814, LM3815
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
www.ti.com
LM3814-7.0, LM3815-7.0
VDD = 5.0V for the following specifications. Supply bypass capacitor is 1µF and filter capacitor is 0.1µF.
Symbol
IACC
Average Current Accuracy
en
(1)
(2)
(3)
(4)
Parameter
Conditions
(3)
at 2.5A current
(4)
Effective Output Noise (rms)
Typ (1)
Limit (2)
Units
2.350 / 2.288
A (min)
2.650 / 2.712
A (max)
2.5
A
120
mA
Typical numbers are at 25°C and represent the most likely parametric norm. Specifications in standard type face are for TJ= 25°C and
those with boldface type apply over full operating temperature ranges.
Limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlation using Statistical
Quality Control (SQC) methods. The limits are used to calculate TI's Averaging Outgoing Quality Level (AOQL).
There is a variation in accuracy over time due to thermal effects. Please refer to the PWM OUTPUT AND CURRENT ACCURACY
section for more information.
The PWM accuracy for LM3814-7.0 and LM3815-7.0 depends on the amount of copper area under pins 1 and 2, and the layout. Please
refer to the PWM OUTPUT AND CURRENT ACCURACY section for more information.
COMMON DEVICE PARAMETERS
Unless otherwise specified, VDD = 5.0V for the following specifications. Supply bypass capacitor is 1µF and filter capacitor is
0.1µF.
Symbol
IQ1
Parameter
Quiescent Current
IQ2
Quiescent Current
DRES
PWM Resolution
tS
Sampling Time
fP
Conditions
Normal Mode, SD = high
Shutdown Mode, SD = low
Typ (1)
Threshold Low Level for SD
1.3
(1)
(2)
(3)
4
Insertion Loss
µA (max)
µA
%
ms
4
ms (min)
10
ms (max)
160
VTL
PI
10
µA
6
1.2
Logic Low Level for PWM
µA (max)
2.5
Threshold High Level for SD
VOL
160
0.8
Frequency of PWM Waveform
Logic High Level for PWM
Units
100
VTH
VOH
Limit (2)
Load current = 1mA, 2V ≤ VDD ≤ 5.25V
Sink current = 1mA, 2V ≤ VDD ≤ 5.25V
ISENSE = 1A (3)
Hz
100
Hz (min)
250
Hz (max)
V
1.8
V (min)
0.7
V (max)
VDD − 0.2
V
V (min)
0.2
V (max)
V
VDD − 0.05
0.04
0.004
V
Ω
Typical numbers are at 25°C and represent the most likely parametric norm. Specifications in standard type face are for TJ= 25°C and
those with boldface type apply over full operating temperature ranges.
Limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlation using Statistical
Quality Control (SQC) methods. The limits are used to calculate TI's Averaging Outgoing Quality Level (AOQL).
The tolerance of the internal lead frame resistor is corrected internally. The temperature coefficient of this resistor is 2600 ppm/°C.
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
OBSOLETE
LM3814, LM3815
www.ti.com
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
TYPICAL PERFORMANCE CHARACTERISTICS
Supply bypass capacitor is 0.1µF and filter capacitor is 0.1µF.
Measured Current vs Actual Current (LM3814-1.0 and
LM3815-1.0)
Measured Current vs Actual Current (LM3814-7.0 and
LM3815-7.0)
Figure 3.
Figure 4.
PWM Frequency vs Supply Voltage
PWM Frequency vs Temperature
Figure 5.
Figure 6.
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
5
OBSOLETE
LM3814, LM3815
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
www.ti.com
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Supply bypass capacitor is 0.1µF and filter capacitor is 0.1µF.
6
Operating Current vs Supply Voltage
Shutdown Current vs Supply Voltage
Figure 7.
Figure 8.
Operating Current vs Temperature
Shutdown Current vs Temperature
Figure 9.
Figure 10.
Current vs Duty Cycle
Accuracy vs Supply Voltage
Figure 11.
Figure 12.
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
OBSOLETE
LM3814, LM3815
www.ti.com
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Supply bypass capacitor is 0.1µF and filter capacitor is 0.1µF.
Accuracy vs Temperature (LM3814-1.0 and LM3815-1.0)
Accuracy vs Temperature (LM3814-7.0 and LM3815-7.0)
Figure 13.
Figure 14.
Error vs Current (LM3814-1.0 and LM3815-1.0)
Error vs Current (LM3814-7.0 and LM3815-7.0)
Figure 15.
Figure 16.
(1)
These curves represent a statistical average such that the noise is insignificant.
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
7
OBSOLETE
LM3814, LM3815
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
www.ti.com
TYPICAL APPLICATION CIRCUITS
In the application circuits, the 0.1µF ceramic capacitor between pins 1 and 8 is used for bypassing, and the
0.1µF ceramic capacitor between pins 3 and 4 is used for filtering. Shutdown (SD) is tied to VDD through a 10kΩ
resistor.
Figure 17. High Side Sense
Figure 18. Low Side Sense
8
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
OBSOLETE
LM3814, LM3815
www.ti.com
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
ITOTAL = 2.2(D1−0.5)IMAX + 2.2(D2−0.5)IMAX where D1 is the duty cycle of PWM1 and D2 is the duty cycle of PWM2.
Please refer to the PRODUCT OPERATION section for more information.
Figure 19. Paralleling LM3814 for Higher Load Current
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
9
OBSOLETE
LM3814, LM3815
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
www.ti.com
Figure 20. High Voltage Operation — VIN Greater Than 5.25V (High Side Sense) (PWM output is referred
to Pin 7)
Figure 21. High Voltage Operation — VIN Greater Than 5.25V (Low Side Sense)
10
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
OBSOLETE
LM3814, LM3815
www.ti.com
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
PRODUCT OPERATION
The current is sampled by the delta-sigma modulator, as illustrated in Figure 22. The pulse density output of the
delta-sigma modulator is digitally filtered. The digital output is then compared to the output of a digital ramp
generator. This produces a PWM output. The duty cycle of the PWM output is proportional to the amount of
current flowing. A duty cycle of 50% indicates zero current flow. If the current is flowing in positive direction, the
duty cycle will be greater than 50%. Conversely, the duty cycle will be less than 50% for currents flowing in the
negative direction. A duty cycle of 95.5% (4.5%) indicates the current is at IMAX (−IMAX). The IC can sense
currents from −IMAX to +IMAX. Options for IMAX are 1A or 10A. The sense current is given by:
ISENSE = 2.2 (D−0.5)(IMAX)
where
•
•
D is the duty cycle of the PWM waveform
IMAX is the full scale current (1A or 10A)
(1)
Similarly, the duty cycle is given by:
D = [ISENSE/(2.2 IMAX)] + 0.5
(2)
For quick reference, see the Conversion Tables in Table 1 and Table 2.
The user should note that, while the LM3814-7.0/ LM3815-7.0 will read 10A full scale, it is rated for 10A
operation for a duration of no more than 200 msec, and 7A operation continuously.
In this IC, the current is averaged over 6 msec time slots. Hence, momentary current surges of less than 6 msec
are tolerated.
This is a sampled data system which requires an anti-aliasing filter, provided by the filter capacitor.
The delta-sigma modulator converts the sensed current to the digital domain. This allows digital filtering, and
provides immunity to current and noise spikes. This type of filtering would be difficult or impossible to accomplish
on an IC with analog components.
When ordering, the user has to specify whether the part is being used for low-side or high-side sense. The user
also needs to specify the full scale value. See the Ordering Information table for details.
Figure 22. Functional block diagram of LM3814 and LM3815
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
11
OBSOLETE
LM3814, LM3815
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
www.ti.com
PWM OUTPUT AND CURRENT ACCURACY
OFFSET
The PWM output is quantized to 128 levels. Therefore, the duty cycle can change only in increments of 1/128.
There is a one-half (0.5) quantization cycle delay in the output of the PWM circuitry. That is to say that instead of
a duty cycle of N/128, the duty cycle actually is (N+½)/128.
The quantization error can be corrected for if a more precise result is desired. To correct for this error, simply
subtract 1/256 from the measured duty cycle.
The extra half cycle delay will show up as a DC offset of ½ bit if it is not corrected for. An offset of ½ bit is 8
times larger than for precision mode parts, and results in approximately 8.8 mA for a 1 Amp part is 88 mA for a 7
Amp part.
JITTER
In addition to quantization, the duty cycle will contain some jitter. The jitter is quite small (for example, the
standard deviation of jitter is only 0.1% for the LM3814/15-1.0). Statistically the jitter can cause an error in a
current sample. Because the jitter is a random variable, the mean and standard deviation are used. The mean, or
average value, of the jitter is zero. The standard deviation (0.1%) can be used to define the peak error caused
from jitter.
The "crest factor" has often been used to define the maximum error caused by jitter. The crest factor defines a
limit within which 99.7% of the samples fall. The crest factor is defined as ±0.3% error in the duty cycle.
Since the jitter is a random variable, averaging multiple outputs will reduce the effective jitter. Obeying statistical
laws, the jitter is reduced by the square root of the number of readings that are averaged. For example, if four
readings of the duty cycle are averaged, the resulting jitter (and crest factor) are reduced by a factor of two.
JITTER AND NOISE
Jitter in the PWM output appears as noise in the current measurement. The Electrical Characteristics show noise
measured in current RMS (root mean square). Arbitrarily one could specify PWM jitter, as opposed to noise. In
either case the effect results in a random error in an individual current measurement.
Noise, just like jitter, can be reduced by averaging many readings. The RMS value of the noise corresponds to
one standard deviation. The "crest factor" can be calculated in terms of current, and is equal to ±3 sigma (RMS
value of the noise).
Noise will also be reduced by averaging multiple readings, and follows the statistical laws of a random variable.
ACCURACY OF 7A VERSIONS
The graph of Figure 23 shows two possible responses to a 7A current step. The flat response shows basically a
7A level with some noise. This is what is possible with a good thick trace and a good thermal connection to the
IC on the sense pins.
The second trace that asymptotically approaches a higher value shows what can happen under extremely poor
thermal conditions. Here a very small wire connects the IC to the current source. The very small wire does not
allow heat in the sense resistor to dissipate. Hence, as the sense resistor heats up, a temperature difference
between the sense element and the die gets larger, and an error develops. Eventually the temperature difference
reaches steady state, which accounts for the under-damped exponential response.
12
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
OBSOLETE
LM3814, LM3815
www.ti.com
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
Figure 23. Transient Response to 7 Amp Step Current
ACCURACY VERSUS NOISE
The graph shown in Figure 24 illustrates the typical response of ±1 Ampere current gauges. In this graph, the
horizontal axis indicates time, and the vertical axis indicates measured current (the PWM duty cycle has been
converted to current). The graph was generated for an actual current of 500 mA.
The difference between successive readings manifests itself as jitter in the PWM output or noise in the current
measurement (when duty cycle of the PWM output is converted to current).
The accuracy of the measurement depends on the noise in the current waveform. The accuracy can be improved
by averaging several outputs. Although there is variation in successive readings, a very accurate measurement
can be obtained by averaging the readings. For example, on averaging the readings shown in this example, the
average current measurement is 497.5 mA (Figure 24). This value is very close to the actual value of 500 mA.
Moreover, the accuracy depends on the number of readings that are averaged.
Figure 24. Typical Response of LM3814-1.0/LM3815-1.0
Look-Up Tables
The following tables show how to convert the duty cycle of the PWM output to a current value, and vice versa.
The quantization error of ½ bit is not shown in these tables. Please see the PWM OUTPUT AND CURRENT
ACCURACY section for more details.
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
13
OBSOLETE
LM3814, LM3815
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
www.ti.com
Table 1. CURRENT TO DUTY CYCLE CONVERSION TABLE
(1)
Sense Current
(Amps) (1)
Duty Cycle
(%)
Sense Current
(Amps) (1)
Duty Cycle
(%)
1.00
95.5
-1.00
4.5
0.95
93.2
-0.95
6.8
0.90
90.9
-0.90
9.1
0.85
88.6
-0.85
11.4
0.80
86.4
-0.80
13.6
0.75
84.1
-0.75
15.9
0.70
81.8
-0.70
18.2
0.65
79.5
-0.65
20.5
0.60
77.3
-0.60
22.7
0.55
75.0
-0.55
25.0
0.50
72.7
-0.50
27.3
0.45
70.5
-0.45
29.5
0.40
68.2
-0.40
31.8
0.35
65.9
-0.35
34.1
0.30
63.6
-0.30
36.4
0.25
61.4
-0.25
38.6
0.20
59.1
-0.20
40.9
0.15
56.8
-0.15
43.2
0.10
54.5
-0.10
45.5
0.05
52.3
-0.05
47.7
0.00
50.0
-0.00
50.0
Maximum Sense Current = 1.0 Amps for LM3814-1.0 and LM3815-1.0
The sense current should be multiplied by 10 for LM3814-7.0 and LM3815-7.0.
Table 2. DUTY CYCLE TO CURRENT CONVERSION TABLE
14
Duty Cycle
(%)
Sense Current
(Amps)
Duty Cycle
(%)
Sense Current
(Amps)
95.5
0.990
50.0
-0.000
92.5
0.935
47.5
-0.055
90.0
0.880
45.0
-0.110
87.5
0.825
42.5
-0.165
85.0
0.770
40.0
-0.220
82.5
0.715
37.5
-0.275
80.0
0.660
35.0
-0.330
77.5
0.605
32.5
-0.385
75.0
0.550
30.0
-0.440
72.5
0.495
27.5
-0.495
70.0
0.440
25.0
-0.550
67.5
0.385
22.5
-0.605
65.0
0.330
20.0
-0.660
62.5
0.275
17.5
-0.715
60.0
0.220
15.0
-0.770
57.5
0.165
12.5
-0.825
55.0
0.110
10.0
-0.880
52.5
0.055
7.5
-0.935
50.0
0.000
5.0
-0.990
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
OBSOLETE
LM3814, LM3815
www.ti.com
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
TIMING DIAGRAM
Duty cycle of the PWM waveform during any sampling interval indicates the current magnitude (average) and
direction during the previous sampling interval.
Figure 25. Typical Timing Diagram for Mostly Positive Current
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
15
OBSOLETE
LM3814, LM3815
SNVS045D – JANUARY 1999 – REVISED APRIL 2013
www.ti.com
REVISION HISTORY
Changes from Revision C (April 2013) to Revision D
•
16
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 15
Submit Documentation Feedback
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: LM3814 LM3815
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other
changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest
issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and
complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale
supplied at the time of order acknowledgment.
TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms
and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary
to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily
performed.
TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and
applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or
other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information
published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or
endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the
third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration
and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered
documentation. Information of third parties may be subject to additional restrictions.
Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service
voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice.
TI is not responsible or liable for any such statements.
Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements
concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support
that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which
anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause
harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use
of any TI components in safety-critical applications.
In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to
help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and
requirements. Nonetheless, such components are subject to these terms.
No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties
have executed a special agreement specifically governing such use.
Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in
military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components
which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and
regulatory requirements in connection with such use.
TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of
non-designated products, TI will not be responsible for any failure to meet ISO/TS16949.
Products
Applications
Audio
www.ti.com/audio
Automotive and Transportation
www.ti.com/automotive
Amplifiers
amplifier.ti.com
Communications and Telecom
www.ti.com/communications
Data Converters
dataconverter.ti.com
Computers and Peripherals
www.ti.com/computers
DLP® Products
www.dlp.com
Consumer Electronics
www.ti.com/consumer-apps
DSP
dsp.ti.com
Energy and Lighting
www.ti.com/energy
Clocks and Timers
www.ti.com/clocks
Industrial
www.ti.com/industrial
Interface
interface.ti.com
Medical
www.ti.com/medical
Logic
logic.ti.com
Security
www.ti.com/security
Power Mgmt
power.ti.com
Space, Avionics and Defense
www.ti.com/space-avionics-defense
Microcontrollers
microcontroller.ti.com
Video and Imaging
www.ti.com/video
RFID
www.ti-rfid.com
OMAP Applications Processors
www.ti.com/omap
TI E2E Community
e2e.ti.com
Wireless Connectivity
www.ti.com/wirelessconnectivity
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2013, Texas Instruments Incorporated
工商网监
湘ICP备2023018690号
