LTC2498 Linear Technology, LTC2498 Datasheet - Page 11

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

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PIN FUNCTIONS
F
controls the internal conversion clock rate. When F
connected to V
oscillator running at 307.2kHz. The conversion clock may
also be overridden by driving the F
clock in order to change the output rate and the digital
fi lter rejection null.
CS (Pin 36): Active LOW Chip Select. A LOW on this pin
enables the digital input/output and wakes up the ADC.
Following each conversion, the ADC automatically enters
the Sleep mode and remains in this low power state as
long as CS is HIGH. A LOW-to-HIGH transition on CS
during the Data Output aborts the data transfer and starts
a new conversion.
FUNCTIONAL BLOCK DIAGRAM
O
(Pin 35): Frequency Control Pin. Digital input that
GND
V
CC
CC
or GND, the converter uses its internal
CH15
REF
REF
COM
CH0
CH1
+
–
•
•
•
SENSOR
TEMP
MUX
MUXOUTP
MUXOUTN
O
pin with an external
ADCINP
ADCINN
Figure 1. Functional Block Diagram
ΔΣ MODULATOR
–
DIFFERENTIAL
3RD ORDER
+
O
is
SDO (Pin 37): Three-State Digital Output. During the data
output period, this pin is used as the serial data output.
When the chip select pin is HIGH, the SDO pin is in a high
impedance state. During the conversion and sleep periods,
this pin is used as the conversion status output. When
the conversion is in progress this pin is HIGH; once the
conversion is complete SDO goes low. The conversion
status is monitored by pulling CS LOW.
SCK (Pin 38): Bidirectional, Digital I/O, Clock Pin. In Internal
Serial Clock Operation mode, SCK is generated internally
and is seen as an output on the SCK pin . In External Serial
Clock Operation mode, the digital I/O clock is externally
applied to the SCK pin. The Serial Clock operation mode
is determined by the logic level applied to the SCK pin at
power up and during the most recent falling edge of CS.
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 fl oating.
AUTOCALIBRATION
DECIMATING FIR
AND CONTROL
ADDRESS
OSCILLATOR
INTERFACE
INTERNAL
SERIAL
2498 BD
F
(INT/EXT)
SDI
SCK
SDO
CS
O
LTC2498
11
2498fc