LTC2424_09 Datasheet, PDF (1/36 Pages) Linear Technology – 4-/8-Channel 20-Bit mPower No Latency DSTM ADCs

LTC2424/LTC2428
4-/8-Channel 20-Bit µPower
No Latency ∆Σ^TM ADCs
FEATURES
s _{Pin Compatible 4-/8-Channel 20-Bit ADCs}
s _{8ppm INL, No Missing Codes at 20 Bits}
s _{4ppm Full-Scale Error and 0.5ppm Offset}
s _{1.2ppm Noise}
s _{Digital Filter Settles in a Single Cycle. Each}
Conversion is Accurate, Even After Changing
Channels
s _{Fast Mode: 16-Bit Noise, 12-Bit TUE at 100sps}
s _{Internal Oscillator—No External Components}
Required
s _{110dB Min, 50Hz/60Hz Notch Filter}
s _{Reference Input Voltage: 0.1V to VCC}
s _{Live Zero—Extended Input Range Accommodates}
12.5% Overrange and Underrange
s _{Single Supply 2.7V to 5.5V Operation}
s _{Low Supply Current (200µA) and Auto Shutdown}
s _{Can Be Interchanged with 24-Bit LTC2404/LTC2408}
U ^{if ZSSET Pin is Grounded}
APPLICATIO S
s _{Weight Scales}
s _{Direct Temperature Measurement}
s _{Gas Analyzers}
s _{Strain-Gage Transducers}
s _{Instrumentation}
s _{Data Acquisition}
s _{Industrial Process Control}
s _{4-Digit DVMs}
DESCRIPTIO
The LTC^®2424/LTC2428 are 4-/8-channel 2.7V to 5.5V
micropower 20-bit A/D converters with an integrated
oscillator, 8ppm INL and 1.2ppm RMS noise. They use
delta-sigma technology and provide single cycle digital
filter settling time (no latency delay) for multiplexed
applications. The first conversion after the channel is
changed is always valid. Through a single pin the LTC2424/
LTC2428 can be configured for better than 110dB rejec-
tion at 50Hz or 60Hz ±2%, or can be driven by an external
oscillator for a user defined rejection frequency in the
range 1Hz to 800Hz. The internal oscillator requires no
external frequency setting components.
The converters accept any external reference voltage from
0.1V to V_CC. With their extended input conversion range of
–12.5% V_REF to 112.5% V_REF (V_REF = FS_SET – ZS_SET) the
LTC2424/LTC2428 smoothly resolve the offset and
overrange problems of preceding sensors or signal con-
ditioning circuits.
The LTC2424/LTC2428 communicate through a flexible
4-wire digital interface which is compatible with SPI and
MICROWIRE^TM protocols.
, LTC and LT are registered trademarks of Linear Technology Corporation.
No Latency ∆Σ is a trademark of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
TYPICAL APPLICATIO
ANALOG
INPUTS
–0.12V_REF TO
1.12V_REF
0.1V TO V_CC
7
4
3
2, 8
9 CH0
MUXOUT
10 CH1
11 CH2
12 CH3
4-/8-CHANNEL
13 CH4*
MUX
14 CH5*
15 CH6*
17 CH7*
5 ZS_SET
ADCIN FS_SET V_CC
+
20-BIT
∆Σ ADC
–
CSADC ²³
CSMUX ²⁰
SCK ²⁵
CLK ¹⁹
D_IN ²¹
SDO ²⁴
LTC2424/LTC2428
GND
26
F_O
1, 6, 16, 18, 22, 27, 28
24248 TA01
*THESE PINS ARE NO CONNECTS ON THE LTC2404
2.7V TO 5.5V
1µF
SERIAL DATA LINK
MICROWIRE AND
SPI COMPATABLE
MPU
V_CC
= INTERNAL OSC/50Hz REJECTION
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/60Hz REJECTION
Total Unadjusted Error (3V Supply)
10
V_CC = 3V
8 V_REF = 2.5V
6
4
2
0
–2
–4
–6
T_A = –55°C, –45°C, 25°C, 90°C
–8
–10
0
0.5
1.0
1.5
2.0
2.5
INPUT VOLTAGE (V)
24248 G01
1