LTC2499_15 Datasheet, PDF (11/34 Pages) Linear Technology – 24-Bit 8-/16-Channel ADC with Easy Drive Input Current Cancellation and I2C Interface

LTC2499
pin functions
COM (Pin 7): The Common Negative Input (IN^–) for All
Single-Ended Multiplexer Configurations. The voltage on
CH0-CH15 and COM pins can have any value between
GND – 0.3V to V_CC + 0.3V. Within these limits, the two
selected inputs (IN⁺ and IN^– ) provide a bipolar input range
(V_IN = IN⁺ – IN^– ) from –0.5 • V_REF to 0.5 • V_REF. Outside
this input range, the converter produces unique overrange
and underrange output codes.
CH0 to CH15 (Pin 8-Pin 23): Analog Inputs. May be pro-
grammed for single-ended or differential mode.
MUXOUTP (Pin 24): Positive Multiplexer Output. Connect
to the input of external buffer/amplifier or short directly
to ADCINP.
ADCINP (Pin 25): Positive ADC Input. Connect to the
output of a buffer/amplifier driven by MUXOUTP or short
directly to MUXOUTP.
ADCINN (Pin 26): Negative ADC Input. Connect to the
output of a buffer/amplifier driven by MUXOUTN or short
directly to MUXOUTN
MUXOUTN (Pin 27): Negative Multiplexer Output. Con-
nect to the input of an external buffer/amplifier or short
directly to ADCINN.
V_CC (Pin 28): Positive Supply Voltage. Bypass to GND with
a 10µF tantalum capacitor in parallel with a 0.1µF ceramic
capacitor as close to the part as possible.
REF⁺, REF^– (Pin 29, Pin 30): Differential Reference Input.
The voltage on these pins can have any value between
GND and V_CC as long as the reference positive input, REF⁺,
remains more positive than the negative reference input,
REF^–, by at least 0.1V. The differential voltage (V_REF = REF⁺
– REF^–) sets the full-scale range for all input channels.
When performing an on-chip measurement, the minimum
value of REF = 2V.
f_O (Pin 35): Frequency Control Pin. Digital input that
controls the internal conversion clock rate. When f_O is
connected to GND, the converter uses its internal oscil-
lator running at 307.2kHz. The conversion clock may also
be overridden by driving the f_O pin with an external clock
in order to change the output rate and the digital filter
rejection null.
CA0, CA1, CA2 (Pins 36, 37, 38): Chip Address Control
Pins. These pins are configured as a three-state (LOW,
HIGH, floating) address control bits for the device I²C
address.
Exposed Pad (Pin 39): Ground. This pin is ground and
must be soldered to the PCB ground plane. For prototyping
purposes, this pin may remain floating.
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
DECIMATING FIR
ADDRESS
I²C
2-WIRE
INTERFACE
2499 BD
For more information www.linear.com/LTC2499
f_O
(INT/EXT)
SDA
SCL
2499fe
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