LTC1860CS8 datasheet(11/16 Pages) LINER

11 / 16 page

LTC1860/LTC1861

18601fa

APPLICATIONS INFORMATION

LTC1860 OPERATION

Operating Sequence

The LTC1860 conversion cycle begins with the rising edge

of CONV. After a period equal to tCONV, the conversion is

ﬁnished. If CONV is left high after this time, the LTC1860

goes into sleep mode drawing only leakage current. On the

falling edge of CONV, the LTC1860 goes into sample mode

and SDO is enabled. SCK synchronizes the data transfer

with each bit being transmitted from SDO on the falling

SCK edge. The receiving system should capture the data

from SDO on the rising edge of SCK. After completing the

data transfer, if further SCK clocks are applied with CONV

low, SDO will output zeros indeﬁnitely. See Figure 1.

Analog Inputs

The LTC1860 has a unipolar differential analog input. The

converter will measure the voltage between the “IN+”

and “IN–” inputs. A zero code will occur when IN+ minus

IN– equals zero. Full scale occurs when IN+ minus IN–

equals VREF minus 1LSB. See Figure 2. Both the “IN+” and

“IN–” inputs are sampled at the same time, so common

mode noise on the inputs is rejected by the ADC. If “IN–”

is grounded and VREF is tied to VCC, a rail-to-rail input

span will result on “IN+” as shown in Figure 3.

Reference Input

The voltage on the reference input of the LTC1860 (and the

LTC1861 MSOP package) deﬁnes the full-scale range of

the A/D converter. These ADCs can operate with reference

voltages from VCC to 1V.

Figure 1. LTC1860 Operating Sequence

Figure 3. LTC1860 with Rail-to-Rail Input Span

Figure 2. LTC1860 Transfer Curve

CONV

tCONV

SCK

SDO

B11 B10

B0*

Hi-Z

SLEEP MODE

tSMPL

tsuCONV

*AFTER COMPLETING THE DATA TRANSFER, IF FURTHER

VIN*

*VIN = IN

+ – IN–

0 0 0 0 0 0 0 0 0 0 0 1

0 0 0 0 0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1 0

•

1860 F02

VREF

IN+

IN–

GND

VCC

SCK

SDO

CONV

LTC1860

1860 F03

VIN = 0V TO VCC

VCC

1 F

SERIAL DATA LINK TO

ASIC, PLD, MPU, DSP

OR SHIFT REGISTERS

LTC1860CS8 Datasheet(PDF) 11 Page - Linear Technology

LTC1860CS8 Datasheet(HTML) 11 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Datasheet Download

Link URL