Datasheet

Threshold High

Threshold Low

INTB

Rp Data

LDC1000

SNOSCX2 –SEPTEMBER 2013

www.ti.com

Each assertion of chip select bar (CSB) starts a new register access. The R/Wb bit in the command field

configures the direction of the access; a value of 0 indicates a write operation and a value of 1 indicates a read

operation. All output data is driven on the falling edge of the serial clock (SCLK), and all input data is sampled on

the rising edge of the serial clock (SCLK). Data is written into the register on the rising edge of the 16th clock. It

is required to deassert CSB after the 16th clock; if CSB is deasserted before the 16th clock, no data write will

occur.

Extended SPI Transactions

A transaction may be extended to multiple registers by keeping the CSB asserted beyond the stated 16 clocks.

In this mode, the register addresses increment automatically. CSB must be asserted during 8*(1+N) clock cycles

of SCLK, where N is the amount of bytes to write or read during the transaction.

During an extended read access, SDO outputs the register contents every 8 clock cycles after the initial 8 clocks

of the command field. During an extended write access, the data is written to the registers every 8 clock cycles

after the initial 8 clocks of the command field.

Extended transactions can be used to read 16-bits of Proximity data and 24-bits of frequency data all in one SPI

transaction by initiating a read from register 0x21.

INTB Pin Modes

The INTB pin is a configurable output pin which can be used to drive an interrupt on an MCU. The LDC1000

provides three different modes on INTB Pin:

1. Comparator Mode

2. Wake-Up Mode

3. DRDY Mode

LDC1000 has a build-in High and Low trigger threshold registers which can be as a comparator with

programmable hysteresis or a special mode which can be used to wake-up an MCU. These modes are explained

in detail below.

Comparator Mode

In the Comparator mode, the INTB pin is asserted or de-asserted when the proximity register value increases

above Threshold High or decreases below Threshold Low registers respectively. In this mode, the LDC1000

essentially behaves as a proximity switch with programmable hysteresis.

Figure 18. Behavior of INTB Pin in Comparator Mode

Product Folder Links: LDC1000