LTC2484CDD#PBF Linear Technology, LTC2484CDD#PBF Datasheet - Page 39

• Manufacturer Part Number: LTC2484CDD#PBF
• Description: IC ADC 24BIT 10-DFN
• Manufacturer: Linear Technology

Specifications of LTC2484CDD#PBF

• Number Of Bits: 24
• Sampling Rate (per Second): 6.8
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 480µW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 10-WFDFN Exposed Pad
• Number Of Elements: 1
• Resolution: 24Bit
• Architecture: Delta-Sigma
• Sample Rate: 0.0075KSPS
• Input Polarity: Bipolar
• Input Type: Voltage
• Rated Input Volt: ±2.75V
• Differential Input: Yes
• Power Supply Requirement: Single
• Single Supply Voltage (typ): 3.3/5V
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (typ): Not RequiredV
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Integral Nonlinearity Error: 10ppm of Vref
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 10
• Package Type: DFN EP
• Input Signal Type: Differential
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
/*** read _ LTC2484() ************************************************************
This is the function that actually does all the work of talking to the LTC2484.
The spi _ read() function performs an 8 bit bidirectional transfer on the SPI bus.
Data changes state on falling clock edges and is valid on rising edges, as
determined by the setup _ spi() line in the initialize() function.
A good starting point when porting to other processors is to write your own
spi _ write function. Note that each processor has its own way of configuring
the SPI port, and different compilers may or may not have built-in functions
for the SPI port. Also, since the state of the LTC2484’s SDO line indicates
when a conversion is complete you need to be able to read the state of this line
through the processor’s serial data input. Most processors will let you read
this pin as if it were a general purpose I/O line, but there may be some that
don’t.
When in doubt, you can always write a “bit bang” function for troubleshooting
purposes.
The “fourbytes” structure allows byte access to the 32 bit return value:
struct fourbytes
Also note that the lower 4 bits are the configuration word from the previous
conversion. The 4 LSBs are cleared so that
they don’t affect any subsequent mathematical operations. While you can do a
right shift by 4, there is no point if you are going to convert to floating point
numbers - just adjust your scaling constants appropriately.
*******************************************************************************/
signed int32 read _ LTC2484(char config)
// Now is the time to switch any multiplexers because the conversion is finished
// and you have the whole data output time for things to settle.
// Clear configuration bits and subtract offset. This results in
// a 2’s complement 32 bit integer with the LTC2484’s MSB in the 2^20 position
{
int8 te0;
int8 te1;
int8 te2;
int8 te3;
};
{
union
output _ low(CS);
while(input(PIN _ C4)) {}
adc _ code.by.te3 = 0;
adc _ code.by.te2 = spi _ read(config);
adc _ code.by.te1 = spi _ read(0);
adc _ code.by.te0 = spi _ read(0);
output _ high(CS);
adc _ code.by.te0 = adc _ code.by.te0 & 0xF0;
adc _ code.bits32 = adc _ code.bits32 - 0x00200000;
return adc _ code.bits32;
} // End of read _ LTC2484()
{
signed int32 bits32;
struct fourbytes by;
} adc _ code;
//
// The make32() function in this compiler will
// also work, but a union of 4 bytes and a 32 bit int
// is probably more portable.
// Define structure of four consecutive bytes
// To allow byte access to a 32 bit int or float.
// adc _ code.by.te1
// Wait for end of conversion. The longest
// adc _ code.by.te2
// adc _ code.bits32
// adc _ code.by.te0
// Enable LTC2484 SPI interface
// you will ever wait is one whole conversion period
// adc _ code.by.te3
// Set upper byte to zero.
// to act as SPI master!! (compiler
// and processor specific.)
// Disable LTC2484 SPI interface
// Read first byte, send config byte
// Read 2nd byte, send speed bit
// Read 3rd byte. ‘0’ argument is necessary
byte 1
byte 2
byte 0
all 32 bits
byte 3
LTC2484
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