LTM2893/LTM2893-1
100MHz Isolated ADC
Serial Interface
FEATURES
DESCRIPTION
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Isolate5 Interface: 6ꢀꢀꢀ4
for 1 Minute
The LTM®2893 is a high speed isolated μModule
(micromodule)SPIinterfacewithADCcontrolsignals.The
LTM2893 is optimized for isolating 1Msps high resolution
18-bitSARADCs,suchastheLTC2338andsimilarfamilies,
and can interface with most general purpose ADCs. The
LTM2893-1 is optimized for isolating the LTC2348 and
similarfamiliesofsimultaneoussamplingADCsthatrequire
writing configuration settings into the ADC. LTM2893
isolates the conversion start, sampling signal, with very
low aperture jitter (30ps) and low latency (20ns).
ꢃMꢂ
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CꢂA (IEC/UL) Approve5V File #299632
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1ꢀꢀMHz ꢂPI-Compatible I/O
Configurable ꢂPI Wor5 Length 8 to 32 dits
Low Jitter Conversion ꢂtart (3ꢀps
Supports Simultaneously Sampled ADCs
Read Only (LTM2893), Read/Write (LTM2893-1)
Three Isolated Multiplexer Select Signals
1.71V to 5.5V I/O Voltages
3V to 5.5V Supply Voltages
High Common Mode Transient Immunity
15mm × 6.25mm BGA Package
)
ꢃMꢂ
The interface enables fast throughput with no cycle
latency, which makes the LTM2893 ideally suited for a
wide variety of applications. The LTM2893 has a high
speed SPI-compatible serial port that supports 1.71V to
5.5V logic and is configurableforADCswith 8to32bit SPI
word lengths. It also isolates three select signals (SA, SB,
SC) for controlling analog multiplexers or gain settings.
APPLICATIONS
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Remote Sensing
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High Speed Data Acquisition
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Industrial Process Control
Test and Measurement Equipment
The isolation barrier tolerates large voltage ground
variations between the logic interface and the isolated
side of the LTM2893. Uninterrupted communication is
maintainedduringvoltagetransientsgreaterthan50kV/µs.
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TYPICAL APPLICATION
LTC2328-18 ADC Isolation AIN = 1ꢀ02ꢁ4V ꢂNꢃ = ꢄ95d
3.3Vi
5Vi
LTC6655-2.048
+15Vi
V
V
3.3V
IN
OUT_F
1µF
5V
5Vi
3.3Vi
SHDN
V
OUT_S
2.2µF
V
L
V
V
V
L2
CC
CC2
0.1µF
10µF
LTM2893
500Ω
6.8nF
MASTER
FPGA
10V
47µF
+
IN
OV
CNV
BUSY
V
REFIN
DD
INPUT
DD
CNV
BUSY
SS
SCK
MISOA
CNV2
BUSY2
SS2
SCK2
MISOA2
REFBUF
CNV
BUSY
CNV2
BUSY2
LT1468
OUT
20Ω
3.3nF
20Ω
+
–
IN
–
IN
SPI
INTERFACE
LTC2328-18
SPI
INTERFACE
SCK
SDO
RDL
CHAIN
IN
BUFFER
INPUT
RETURN
SA
SB
SC
SA2
SB2
SC2
VDDLBYP
1µF
SELECT
SELECT2
2.2µF
–15Vi
28931 TA01a
Rev C
1
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