LTC2452 pin FuncTionsSCK (Pin 1): Serial Clock Input. SCK synchronizes the IN– (Pin 5), IN+ (Pin 6): Differential Analog Input. serial data output. While digital data is available (the ADC CS (Pin 7): Chip Select (Active LOW) Digital Input. A LOW is not in CONVERT state) and CS is LOW (ADC is not in on this pin enables the SDO digital output. A HIGH on this SLEEP state) a new data bit is produced at the SDO output pin places the SDO output pin in a high impedance state. pin following every falling edge applied to the SCK pin. SDO (Pin 8): Three-State Serial Data Output. SDO is used GND (Pin 2): Ground. Connect to a ground plane through for serial data output during the DATA OUTPUT state and a low impedance connection. can be used to monitor the conversion status. REF (Pin 3): Reference Input. The voltage on REF can have Exposed Pad (Pin 9): Ground. Must be soldered to PCB any value between 2.5V and VCC. The reference voltage ground. For prototyping purposes, this pad may remain sets the full-scale range. floating. VCC (Pin 4): Positive Supply Voltage. Bypass to GND (Pin 2) with a 10µF capacitor in parallel with a low-series- inductance 0.1µF capacitor located as close to the LTC2452 as possible. block DiagraM 3 4 REF VCC CS 7 IN+ SPI 16-BIT SDO ΔΣ 6 INTERFACE 8 A/D CONVERTER SCK 1 DECIMATING – SINC FILTER IN– 16-BIT ΔΣ 5 A/D CONVERTER INTERNAL OSCILLATOR 2, 9 GND 2452 BD Figure 1. Functional Block DiagramapplicaTions inForMaTionCONVERTER OPERATION The operating cycle begins with the CONVERT state, is followed by the SLEEP state, and ends with the DATA OUT- Converter Operation Cycle PUT state (see Figure 2). The 3-wire interface consists of The LTC2452 is a low power, fully differential, delta-sigma serial data output (SDO), serial clock input (SCK), and the analog-to-digital converter with a simple 3-wire SPI in- active low chip select input (CS). terface (see Figure 1). Its operation is composed of three The CONVERT state duration is determined by the LTC2452 successive states: CONVERT, SLEEP and DATA OUTPUT. conversion time (nominally 16.6 milliseconds). Once 2452fd 6 For more information www.linear.com/LTC2452