Datasheet LTC1863L, LTC1867L (Analog Devices) - 10

LTC1863L/LTC1867L
APPLICATIONS INFORMATION Table 2. Channel Configuration (When COM = 1, CH7/COM Pin
LT®1468: 90MHz, 22V/µs 16-bit accurate amplifier
Is Used as COMMON)
LT1469: Dual LT1468
CHANNEL CONFIGURATION SD OS S1 S0 COM “+” “–”
LT1490A/LT1491A: Dual/quad micropower amplifiers, 1 0 0 0 1 CH0 CH7/COM 50µA/amplifier max, 500µV offset, common mode range 1 0 0 1 1 CH2 CH7/COM extends 44V above V– independent of V+, 3V, 5V and 1 0 1 0 1 CH4 CH7/COM ±15V supplies. 1 0 1 1 1 CH6 CH7/COM 1 1 0 0 1 CH1 CH7/COM LT1568: Very low noise, active RC filter building block, 1 1 0 1 1 CH3 CH7/COM cutoff frequency up to 10MHz, 2.7V to ±5V supplies. 1 1 1 0 1 CH5 CH7/COM LT1638/LT1639: Dual/quad 1.2MHz, 0.4V/µs amplifiers, 230µA per amplifier, 3V, 5V and ±15V supplies.
Driving the Analog Inputs
LT1881/LT1882: Dual and quad, 200pA bias current, rail- The analog inputs of the LTC1863L/LTC1867L are easy to-rail output op amps, up to ±15V supplies. to drive. Each of the analog inputs can be used as a sin- gle-ended input relative to the GND pin (CH0-GND, CH1- LTC1992-2: Gain of 2 ful y differential input/output GND, etc) or in pairs (CH0 and CH1, CH2 and CH3, CH4 amplifier/driver, 2.5mV offset, CLOAD stable, 2.7V to ±5V and CH5, CH6 and CH7) for differential inputs. In addi- supplies. tion, CH7 can act as a COM pin for both single-ended LT1995: 30MHz, 1000V/µs gain selectable amplifier, pin and differential modes if the COM bit in the input word is configurable as a difference amplifier, inverting and non- high. Regardless of the MUX configuration, the “+” and inverting amplifier, ±2.5V to ±15V supplies. “–” inputs are sampled at the same instant. Any unwanted signal that is common mode to both inputs will be reduced LTC6912: Dual programmable gain amplifiers with SPI by the common mode rejection of the sample-and-hold serial interface, 2mV offset, 2.7V to ±5V supplies. circuit. The inputs draw only one small current spike LTC6915: Zero drift, instrumentation amplifier with SPI while charging the sample-and-hold capacitors during programmable gain, 125dB CMRR, 0.1% gain accuracy, the acquire mode. In conversion mode, the analog inputs 10µV offset. draw only a small leakage current. If the source impedance of the driving circuit is low then the LTC1863L/LTC1867L
Input Filtering
inputs can be driven directly. More acquisition time should The noise and the distortion of the input amplifier and be allowed for a higher impedance source. other circuitry must be considered since they will add The following list is a summary of the op amps that are to the LTC1863L/LTC1867L noise and distortion. Noisy suitable for driving the LTC1863L/LTC1867L. input circuitry should be filtered prior to the analog inputs to minimize noise. A simple 1-pole RC filter is sufficient 1000pF 50Ω ANALOG 50Ω CH0 INPUT CH0 LTC1863L/ DIFFERENTIAL 2000pF LTC1863L/ LTC1867L ANALOG 1000pF LTC1867L INPUTS 50Ω GND CH1 1000pF REFCOMP REFCOMP 10µF 10µF 1863L7L F01a 1863L7L F01b
Figure 1a. Optional RC Input Filtering for Single-Ended Input Figure 1b. Optional RC Input Filtering for Differential Inputs
1863l7lfe 10 For more information www.linear.com/LTC1863L Document Outline Description Absolute Maximum Ratings Pin Configuration Typical Performance Characteristics Pin Functions Package Description Related Parts