Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.NET

X  

LM12454 Datasheet(PDF) 26 Page - Texas Instruments

Part # LM12454
Description  LM12454/LM12458/LM12H458 12-Bit Sign Data Acquisition System with Self-Calibration
Download  45 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  TI1 [Texas Instruments]
Direct Link  http://www.ti.com
Logo TI1 - Texas Instruments

LM12454 Datasheet(HTML) 26 Page - Texas Instruments

Back Button LM12454_14 Datasheet HTML 22Page - Texas Instruments LM12454_14 Datasheet HTML 23Page - Texas Instruments LM12454_14 Datasheet HTML 24Page - Texas Instruments LM12454_14 Datasheet HTML 25Page - Texas Instruments LM12454_14 Datasheet HTML 26Page - Texas Instruments LM12454_14 Datasheet HTML 27Page - Texas Instruments LM12454_14 Datasheet HTML 28Page - Texas Instruments LM12454_14 Datasheet HTML 29Page - Texas Instruments LM12454_14 Datasheet HTML 30Page - Texas Instruments Next Button
Zoom Inzoom in Zoom Outzoom out
 26 / 45 page
background image
LM12454, LM12458, LM12H458
SNAS079A – MAY 2004 – REVISED FEBRUARY 2006
www.ti.com
Two different calibration modes are available; one compensates for offset voltage, or zero error, while the other
corrects both offset error and the ADC's linearity error.
When correcting offset only, the offset error is measured once and a correction coefficient is created. During the
full calibration, the offset error is measured eight times, averaged, and a correction coefficient is created. After
completion of either calibration mode, the offset correction coefficient is stored in an internal offset correction
register.
The LM12(H)454/8's overall linearity correction is achieved by correcting the internal DAC's capacitor mismatch.
Each capacitor is compared eight times against all remaining smaller value capacitors and any errors are
averaged. A correction coefficient is then created and stored in one of the thirteen internal linearity correction
registers. An internal state machine, using patterns stored in an internal 16 x 8-bit ROM, executes each
calibration algorithm.
Once calibrated, an internal arithmetic logic unit (ALU) uses the offset correction coefficient and the 13 linearity
correction coefficients to reduce the conversion's offset error and linearity error, in the background, during the 12-
bit + sign conversion. The 8-bit + sign conversion and comparison modes use only the offset coefficient. The 8-
bit + sign mode performs a conversion in less than half the time used by the 12-bit + sign conversion mode.
The LM12(H)454/8's “watchdog” mode is used to monitor a single-ended or differential signal's amplitude. Each
sampled signal has two limits. An interrupt can be generated if the input signal is above or below either of the
two limits. This allows interrupts to be generated when analog voltage inputs are “inside the window” or,
alternatively, “outside the window”. After a “watchdog” mode interrupt, the processor can then request a
conversion on the input signal and read the signal's magnitude.
The analog input multiplexer can be configured for any combination of single-ended or fully differential operation.
Each input is referenced to ground when a multiplexer channel operates in the single-ended mode. Fully
differential analog input channels are formed by pairing any two channels together.
The LM12454's multiplexer outputs and S/H inputs (MUXOUT+, MUXOUT
− and S/H IN+, S/H IN−) provide the
option for additional analog signal processing. Fixed-gain amplifiers, programmable-gain amplifiers, filters, and
other processing circuits can operate on the signal applied to the selected multiplexer channel(s). If external
processing is not used, connect MUXOUT+ to S/H IN+ and MUXOUT
− to S/H IN−.
The LM12(H)454/8's internal S/H is designed to operate at its minimum acquisition time (1.13
μs, 12 bits) when
the source impedance, RS, is ≤ 60Ω (fCLK ≤ 8 MHz). When 60Ω < RS ≤ 4.17 kΩ, the internal S/H's acquisition
time can be increased to a maximum of 4.88
μs (12 bits, fCLK = 8 MHz). See Section 2.1 (Instruction RAM “00”)
Bits 12–15 for more information.
An internal 2.5V bandgap reference output is available at pin 44. This voltage can be used as the ADC reference
for ratiometric conversion or as a virtual ground for front-end analog conditioning circuits. The VREFOUT pin should
be bypassed to ground with a 100
μF capacitor.
Microprocessor overhead is reduced through the use of the internal conversion FIFO. Thirty-two consecutive
conversions can be completed and stored in the FIFO without any microprocessor intervention. The
microprocessor can, at any time, interrogate the FIFO and retrieve its contents. It can also wait for the
LM12(H)454/8 to issue an interrupt when the FIFO is full or after any number (
≤32) of conversions have been
stored.
Conversion sequencing, internal timer interval, multiplexer configuration, and many other operations are
programmed and set in the Instruction RAM.
A diagnostic mode is available that allows verification of the LM12(H)458's operation. The diagnostic mode is
disabled in the LM12454. This mode internally connects the voltages present at the VREFOUT, VREF+, VREF−, and
GND pins to the internal VIN+ and VIN− S/H inputs. This mode is activated by setting the Diagnostic bit (Bit 11) in
the Configuration register to a “1”. More information concerning this mode of operation can be found in Section
2.2.
26
Submit Documentation Feedback
Copyright © 2004–2006, Texas Instruments Incorporated
Product Folder Links: LM12454 LM12458 LM12H458


Similar Part No. - LM12454_14

ManufacturerPart #DatasheetDescription
logo
National Semiconductor ...
LM12454CIV NSC-LM12454CIV Datasheet
991Kb / 43P
   12-Bit Sign Data Acquisition System with Self-Calibration
LM12454CIV NSC-LM12454CIV Datasheet
1Mb / 36P
   12-Bit Sign Data Acquisition System with Self-Calibration
LM12454 NSC-LM12454_06 Datasheet
1Mb / 36P
   12-Bit Sign Data Acquisition System with Self-Calibration
More results

Similar Description - LM12454_14

ManufacturerPart #DatasheetDescription
logo
National Semiconductor ...
LM12454 NSC-LM12454 Datasheet
991Kb / 43P
   12-Bit Sign Data Acquisition System with Self-Calibration
LM12454 NSC-LM12454_06 Datasheet
1Mb / 36P
   12-Bit Sign Data Acquisition System with Self-Calibration
logo
Texas Instruments
LM12L458 TI1-LM12L458_16 Datasheet
803Kb / 38P
[Old version datasheet]   12-Bit Sign Data Acquisition System with Self-Calibration
logo
National Semiconductor ...
LM12L458 NSC-LM12L458 Datasheet
695Kb / 36P
   12-Bit Sign Data Acquisition System with Self-Calibration
LM12L458 NSC-LM12L458_06 Datasheet
884Kb / 29P
   12-Bit Sign Data Acquisition System with Self-Calibration
logo
Texas Instruments
LM12454 TI1-LM12454 Datasheet
1Mb / 43P
[Old version datasheet]   12-Bit Sign Data Acquisition System
logo
National Semiconductor ...
LM12434 NSC-LM12434 Datasheet
1Mb / 80P
   Sign Data Acquisition System with Serial I/O and Self-Calibration
logo
Micro Linear Corporatio...
ML2200 MICRO-LINEAR-ML2200 Datasheet
1Mb / 28P
   12-Bit Plus Sign Data Acquisition Peripheral
logo
Sipex Corporation
SP8121 SIPEX-SP8121 Datasheet
168Kb / 13P
   Monolithic, 12-Bit Data Acquisition System
SP8481 SIPEX-SP8481 Datasheet
208Kb / 12P
   Monolithic, 12-Bit Data Acquisition System
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.NET
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com