Datasheet LTC2983 (Analog Devices) - 9

LTC2983
PIN FUNCTIONS GND (Pins 1, 3, 5, 7, 9, 12, 15, 44):
Ground. Connect cycle is in progress. This pin goes HIGH at the conclusion each of these pins to a common ground plane through a of the start-up state or conversion cycle. low impedance connection. All eight pins must be grounded
SCK (Pin 38):
Serial Clock Pin. Data is shifted out of the for proper operation. device on the falling edge of SCK and latched by the device
VDD (Pins 2, 4, 6, 8, 45):
Analog Power Supply. Tie all on the rising edge. five pins together and bypass as close as possible to the
SDO (Pin 39):
Serial Data Out. During the data output state, device, to ground with a 0.1μF capacitor. this pin is used as the serial data output. When the chip
VREF_BYP( Pin 11):
Internal Reference Power. This is an select pin is HIGH, the SDO pin is in a high impedance state. internal supply pin, do not load this pin with external
SDI (Pin 40):
Serial Data Input. Used to program the device. circuitry. Decouple with a 0.1µF capacitor to GND. Data is latched on the rising edge of SCK.
VREFOUT (Pin 13):
Reference Output Voltage. Short to
CS (Pin 41):
Active Low Chip Select. A low on this pin VREFP. A minimum 1μF capacitor to ground is required. enables the digital input/output. A HIGH on this pin Do not load this pin with external circuitry. places SDO in a high impedance state. A falling edge on
VREFP (Pin 14):
Positive Reference Input. Tie to VREFOUT. CS marks the beginning of a SPI transaction and a rising
CH1 to CH20 (Pin 16 to Pin 35):
Analog Inputs. May be edge marks the end. programmed for single-ended, differential, or ratiometric
RESET (Pin 42):
Active Low Reset. While this pin is LOW, operation. The voltage on these pins can have any value the device is forced into the reset state. Once this pin is between GND – 50mV and VDD – 0.3V. Unused pins can returned HIGH, the device initiates its start-up sequence. be grounded or left floating.
LDO (Pin 43):
2.5V LDO Output. Bypass with a 10µF
COM (Pin 36):
Analog Input. The common negative input capacitor to GND. This is an internal supply pin, do not for all single-ended configurations. The voltage on this load this pin with external circuitry. pin can have any value between GND – 50mV and VDD –
Q3, Q2, Q1 (Pins 46, 47, 48):
External Bypass Pins for 0.3V. This pin is typically tied to ground for temperature –200mV integrated Charge Pump. Tie a 10µF X7R capaci- measurements. tor between Q1 and Q2 close to each pin. Tie a 10µF X5R
INTERRUPT (Pin 37):
This pin outputs a LOW when the capacitor from Q3 to Ground. These are internal supply device is busy either during start-up or while a conversion pins, do not make additional connections. 2983fc For more information www.linear.com/LTC2983 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Complete System Electrical Characteristics Pin Configuration ADC Electrical Characteristics Reference Electrical Characteristics Digital Inputs and Digital Outputs Typical Performance Characteristics Pin Functions Block Diagram Test Circuits Timing Diagram Overview Applications Information Thermocouple Measurements Diode Measurements RTD Measurements Thermistor Measurements Direct ADC Measurements Supplemental Information Fault Protection and Anti-Aliasing 2- and 3-Cycle Conversion Modes Running Conversions Consecutively on Multiple Channels MUX Configuration Delay Global Configuration Register Custom Thermocouples Custom RTDs Custom Thermistors Package Description Revision History Typical Application Related Parts