1
LTC2404/LTC2408
4-/8-Channel 24-Bit µPower
No Latency ∆Σ
TM
ADCs
The LTC
®
2404/LTC2408 are 4-/8-channel 2.7V to 5.5V
micropower 24-bit A/D converters with an integrated
oscillator, 4ppm INL and 0.3ppm 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 LTC2404/
LTC2408 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 120Hz. 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
the
LTC2404/LTC2408
smoothly resolve the offset and overrange problems of
preceding sensors or signal conditioning circuits.
The
LTC2404/LTC2408
communicate through a flexible
4-wire digital interface which is compatible with SPI and
MICROWIRE
TM
protocols.
■
Pin Compatible 4-/8-Channel 24-Bit ADCs
■
Single Conversion Digital Filter Settling Time
Simplifies Multiplexing
■
4ppm INL, No Missing Codes
■
4ppm Full-Scale Error
■
0.5ppm Offset
■
0.3ppm Noise
■
Internal Oscillator—No External Components
Required
■
110dB Min, 50Hz/60Hz Notch Filter
■
Reference Input Voltage: 0.1V to V
CC
■
Live Zero—Extended Input Range Accommodates
12.5% Overrange and Underrange
■
Single Supply 2.7V to 5.5V Operation
■
Low Supply Current (200µA) and Auto Shutdown
Total Unadjusted Error vs Output Code
, 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.
■
Weight Scales
■
Direct Temperature Measurement
■
Gas Analyzers
■
Strain Gauge Transducers
■
Instrumentation
■
Data Acquisition
■
Industrial Process Control
■
6-Digit DVMs
ANALOG
INPUTS
–0.12V
REF
TO
1.12V
REF
2404/08 TA01
CH0
CH1
CH2
CH3
CH4*
CH5*
CH6*
CH7*
9
10
11
12
13
14
15
17
4-/8-CHANNEL
MUX
*THESE PINS ARE NO CONNECTS ON THE LTC2404
GND
1, 5, 6, 16, 18, 22, 27, 28
MPU
SERIAL DATA LINK
MICROWIRE AND
SPI COMPATABLE
23
20
19
25
21
24
CSADC
CSMUX
SCK
CLK
D
IN
SDO
26
F
O
24-BIT
∆Σ ADC
LTC2404/LTC2408
0.1V TO V
CC
ADCINMUXOUT
7 4 3 2, 8
1µF
2.7V TO 5.5V
V
REF
V
CC
= INTERNAL OSC/50Hz REJECTION
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/60Hz REJECTION
V
CC
OUTPUT CODE (DECIMAL)
0 8,338,608 16,777,215
LINEARITY ERROR (ppm)
2404/08 TA02
10
8
6
4
2
0
–2
–4
–6
–8
–10
V
DD
= 5V
V
REF
= 5V
T
A
= 25°C
F
O
= LOW
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
