LTC2442 Datasheet, PDF (1/32 Pages) Linear Technology – 24-Bit High Speed 4-Channel Delta-Sigma ADC with Integrated Amplifi er

FEATURES
■ _{1ppm Linearity with No Missing Codes}
■ _{Integrated Amplifier for Direct Sensor Digitization}
■ _{2 Differential or 4 Single-Ended Input Channels}
■ _{Up to 8kHz Output Rate}
■ _{Up to 4kHz Multiplexing Rate}
■ _{Selectable Speed/Resolution}
2µV_RMS Noise at 1.76kHz Output Rate
220nV_RMS Noise at 13.8Hz Output Rate with
Simultaneous 50Hz/60Hz Rejection
■ _{Guaranteed Modulator Stability and Lock-Up}
Immunity for any Input and Reference Conditions
■ _{<5µV Offset (4.5V < VCC < 5.5V, –40°C to 85°C)}
■ _{Differential Input and Differential Reference with GND}
to V_CC Common Mode Range
■ _{No Latency Mode, Each Conversion is Accurate Even}
After a New Channel is Selected
■ _{Internal Oscillator—No External Components}
■ _{36-Lead SSOP Package}
U
APPLICATIO S
■ _{Auto Ranging 6-Digit DVMs}
■ _{High Speed Multiplexing}
■ _{Weight Scales}
■ _{Direct Temperature Measurement}
■ _{High Speed Data Acquisition}
LTC2442
24-Bit High Speed
4-Channel ΔΣ ADC
with Integrated Amplifier
DESCRIPTIO
The LTC^®2442 is an ultra high precision, variable speed,
24-bit ΔΣ^TM ADC with integrated amplifier. The amplifier
can be configured as a buffer for easy input drive of high
impedance sensors. 1 part-per-million (ppm) linearity is
achievable when the amplifier is configured in unity gain.
External resistors can be used to set a gain for increased
resolution of low level input signals. The positive and
negative amplifier supply pins may be tied directly to V_CC
(4.5V to 5.5V) and GND or biased above V_CC and below
GND for rail-to-rail input signals.
The proprietary ΔΣ architecture ensures stable DC ac-
curacy through continuous transparent calibration. Ten
speed/resolution combinations from 6.9Hz/220nV_RMS to
3.5kHz/25µV_RMS can be selected with no latency or shift
in DC accuracy. Additionally, a 2X speed mode can be
selected enabling output rates up to 7kHz (8kHz with an
external oscillator) with one cycle latency.
Any combination of single-ended (up to 4 inputs) or dif-
ferential (up to 2 inputs) can be selected with a common
mode input range from ground to V_CC. While operating in
the 1X speed mode the first conversion following a new
speed/resolution or channel selection is valid.
, LTC and LT are registered trademarks of Linear Technology Corporation.
No Latency ∆Σ is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6140950, 6169506, 6411242, 6639526.
TYPICAL APPLICATIO
High Precision Data Acquisition System
0.1µF
4.5V TO 15V 4.5V TO 5.5V
HIGH Z
2-CHANNEL
DIFFERENTIAL/
4-CHANNEL
SINGLE ENDED
CH0
CH1
CH2 AUTO-CAL
CH3
COM
V⁺ VREF⁺ V_CC
F_O
–
SDI
+
VARIABLE SPEED/
SCK
RESOLUTION
SDO
+
DIFFERENTIAL
24-BIT ∆Σ ADC
CS
–
0.1µF
V^{– V}REF^– GND _LTC2442
2442 TA01
–15V TO 0V
= EXTERNAL OSCILLATOR
= INTERNAL OSCILLATOR
(SIMULTANEOUS 50Hz/60Hz
REJECTION AT 6.9Hz OUTPUT RATE)
4-WIRE
SPI INTERFACE
LTC2442 Integral Non-Linearity
5
4
V_INCM = 2.048V
V_REF = 4.096V
3 ^VVC+C_==5V5V
2 ^{V– = 0V}
1
0
–1
–2
–3
–4
–5
–2.048
–1.024
0
1.024
V_IN DIFFERENTIAL (V)
2.048
2442 TA02
2442f
1