LTC2498 Linear Technology, LTC2498 Datasheet - Page 10

• Manufacturer Part Number: LTC2498
• Description: 24-Bit 8-/16-Channel ADC
• Manufacturer: Linear Technology

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LTC2498
TYPICAL PERFORMANCE CHARACTERISTICS
PIN FUNCTIONS
GND (Pins 1, 3, 4, 5, 6, 31, 32, 33): Ground. Multiple
ground pins internally connected for optimum ground cur-
rent fl ow and V
pins to a common ground plane through a low impedance
connection. All eight pins must be connected to ground
for proper operation.
NC (Pin 2): No Connection, this pin can be left fl oating
or tied to GND.
COM (Pin 7): The common negative input (IN
single-ended multiplexer confi gurations. The voltage on
CH0 to CH15 and COM pins can have any value between
GND – 0.3V to V
selected inputs (IN
(V
this input range, the converter produces unique over-range
and under-range output codes.
CH0 to CH15 (Pins 8 to 23): Analog Inputs. May be pro-
grammed for single-ended or differential mode.
MUXOUTP (Pin 24): Positive Multiplexer Output. Used
to drive an external buffer/amplifi er or can be shorted
directly to ADCINP .
ADCINP (Pin 25): Positive ADC Input. Tie to the output
of a buffer/amplifi er driven by MUXOUTP or tie directly
to MUXOUTP .
10
IN
= IN
+
– IN
–
CC
) from –0.5 • V
–100
–140
–120
CC
–60
–20
–40
–80
decoupling. Connect each one of these
+
0
and IN
+ 0.3V. Within these limits, the two
0
PSRR vs Frequency at V
(2x Speed Mode)
V
REF
REF
IN
IN
F
T
O
A
CC
+
–
20
= GND
= 25°C
+
–
= GND
= GND
= 4.1V DC ±1.4V
= 2.5V
= GND
40 60
–
) provide a bipolar input range
FREQUENCY AT V
80
REF
100
to 0.5 • V
120
140
CC
(Hz)
160
CC
180
REF
200
2498 G37
. Outside
–
) for all
220
ADCINN (Pin 26): Negative ADC Input. Tie to the output
of a buffer/amplifi er driven by MUXOUTN or tie directly
to MUXOUTN.
MUXOUTN (Pin 27): Negative Multiplexer Output. Used
to drive an external buffer/amplifi er or can be shorted
directly to ADCINN.
V
a 10μF tantalum capacitor in parallel with a 0.1μF ceramic
capacitor as close to the part as possible.
REF
The voltage on these pins can have any value between
GND and V
remains more positive than the negative reference input,
REF
– REF
When performing an on-chip temperature measurement,
the minimum value of REF = 2V.
SDI (Pin 34): Serial Data Input. This pin is used to select the
line frequency rejection mode, 1x or 2x mode, temperature
sensor, as well as the input channel. The serial data input
is applied under control of the serial clock (SCK) during
the data output/input operation. The fi rst conversion fol-
lowing a new input or mode change is valid.
CC
–100
–120
–140
–20
–40
–60
–80
(Pin 28): Positive Supply Voltage. Bypass to GND with
–
+
30600
0
, by at least 0.1V. The differential voltage (REF = REF
(Pin 29), REF
–
PSRR vs Frequency at V
(2x Speed Mode)
V
REF
REF
IN
IN
F
T
) sets the full-scale range for all input channels.
O
CC
A
+
–
= GND
= 25°C
+
–
= GND
= GND
= 4.1V DC ±0.7V
= 2.5V
= GND
CC
30650
FREQUENCY AT V
as long as the reference positive input, REF
–
30700
(Pin 30): Differential Reference Input.
CC
(Hz)
30750
CC
2498 G38
30800
2498fc
+
+
,