LTC2495_15 Datasheet, PDF (12/34 Pages) Linear Technology – 16-Bit 8-/16-Channel ADC with PGA, Easy Drive and I2C Interface

LTC2495
FUNCTIONAL Block Diagram
TEMP
SENSOR
V_CC
GND
REF⁺
REF^–
MUXOUTP ADCINP
CH0
CH1
•
•
MUX
•
CH15
COM
–+
DIFFERENTIAL
3RD ORDER
∆Σ MODULATOR
MUXOUTN ADCINN
AUTOCALIBRATION
AND CONTROL
INTERNAL
OSCILLATOR
f_O
(INT/EXT)
I²C
SDA
2-WIRE
INTERFACE
SCL
DECIMATING FIR
ADDRESS
2495 BD
Applications Information
CONVERTER OPERATION
Converter Operation Cycle
The LTC2495 is a multichannel, low power, delta-sigma,
analog-to-digital converter with a 2-wire, I²C interface. Its
operation is made up of four states (see Figure 1). The con-
verter operating cycle begins with the conversion, followed
by the sleep state, and ends with the data input/output cycle.
POWER-ON RESET
DEFAULT CONFIGURATION:
IN⁺ = CH0, IN^– = CH1
50Hz/60Hz REJECTION
1x OUTPUT, GAIN = 1
CONVERSION
Initially, at power-up, the LTC2495 performs a conversion.
Once the conversion is complete, the device enters the
sleep state. While in the sleep state, power consumption
is reduced by two orders of magnitude. The part remains
in the sleep state as long it is not addressed for a read/
write operation. The conversion result is held indefinitely
in a static shift register while the part is in the sleep state.
SLEEP
NO
ACKNOWLEDGE
YES
The device will not acknowledge an external request during
the conversion state. After a conversion is finished, the
device is ready to accept a read/write request. Once the
LTC2495 is addressed for a read operation, the device be-
gins outputting the conversion result under the control of
the serial clock (SCL). There is no latency in the conversion
result. The data output is 24 bits long and contains a 16-bit
plus sign conversion result. Data is updated on the falling
edges of SCL allowing the user to reliably latch data on
the rising edge of SCL. A new conversion is initiated by
DATA OUTPUT/INPUT
NO
STOP
OR READ
24 BITS
YES
2495 F01
Figure 1. State Transition Table
2495fe
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For more information www.linear.com/LTC2495