LTM2893/LTM2893-1
100MHz Isolated ADC
Serial Interface
FEATURES
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DESCRIPTION
The
LTM
®
2893
is a high speed isolated μModule
(micromodule) SPI interface with ADC control signals. The
LTM2893 is optimized for isolating 1Msps high resolution
18-bit SAR ADCs, such as the LTC2338 and similar families,
and can interface with most general purpose ADCs. The
LTM2893-1 is optimized for isolating the LTC2348 and
similar families of simultaneous sampling ADCs that require
writing configuration settings into the ADC. LTM2893
isolates the conversion start, sampling signal, with very
low aperture jitter (30ps) and low latency (20ns).
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 configurable for ADCs with 8 to 32 bit SPI
word lengths. It also isolates three select signals (SA, SB,
SC) for controlling analog multiplexers or gain settings.
The isolation barrier tolerates large voltage ground
variations between the logic interface and the isolated
side of the LTM2893. Uninterrupted communication is
maintained during voltage transients greater than 50kV/µs.
Isolated Interface: 6000V
RMS
for 1 Minute
UL-CSA Recognition Pending
100MHz SPI-Compatible I/O
Configurable SPI Word Length 8 to 32 Bits
Low Jitter Conversion Start (30ps
RMS
)
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
APPLICATIONS
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Remote Sensing
High Speed Data Acquisition
Industrial Process Control
Test and Measurement Equipment
L,
LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks
and SoftSpan is a trademark of Analog Devices, Inc. All other trademarks are the property of
their respective owners.
TYPICAL APPLICATION
LTC2328-18 ADC Isolation A
IN
= ±10.24V, SNR = 95dB
3.3Vi
3.3V
5V
V
L
MASTER
FPGA
LTM2893
CNV
BUSY
SS
SCK
MISOA
SA
SB
SC
ISOLATION BARRIER
CNV
BUSY
SPI
INTERFACE
BUFFER
SELECT
CNV2
BUSY2
SPI
INTERFACE
CNV2
BUSY2
SS2
SCK2
MISOA2
SA2
SB2
SC2
OV
DD
CNV
BUSY
SCK
SDO
RDL
CHAIN
V
DD
REFIN
REFBUF
IN
+
LTC2328-18
IN
–
VDDLBYP
2.2µF
–15Vi
V
CC
5Vi
V
CC2
3.3Vi
V
L2
0.1µF
10µF
47µF
20
3.3nF
20
1µF
IN
+
OUT LT1468
IN
–
6.8nF
500
±10V
INPUT
5Vi
LTC6655-2.048
V
IN
V
OUT_F
2.2µF
+15Vi
1µF
SHDN
V
OUT_S
SELECT2
INPUT
RETURN
28931 TA01a
28931fb
For more information
www.linear.com/LTM2893
1
LTM2893/LTM2893-1
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
1
ON
Supply Voltages
V
L
to GND ................................................ –0.3V to 6V
V
CC
to GND .............................................. –0.3V to 6V
Isolated Supply Voltages
V
L2
to GND2 ............................................ –0.3V to 6V
V
CC2
to GND2 .......................................... –0.3V to 6V
Logic Signals
ON, CNV, BUSY, SA, SB, SC,
SS, CSC,
MISOA, MISOB,
SCK, MOSI ........................... GND – 0.3V to V
L
+ 0.3V
FAULT
........................................... GND – 0.3V to 6.3V
Isolated Signals
MISOA2, MISOB2, ON2, BUSY2,
BUSYS, MOSI2, CNV2, SCK2,
SS2,
SA2, SB2, SC2 ..................GND2 – 0.3V to V
L2
+ 0.3V
Operating Temperature Range (Note 11)
LTM2893C ............................................... 0°C to 70°C
LTM2893I ............................................–40°C to 85°C
LTM2893H ......................................... –40°C to 125°C
Storage Temperature Range .............. –55°C to 125°C
Maximum Internal Operating Temperature ....... 125°C
Peak Solder Reflow Temperature ...................... 260°C
2
SS
3
MOSI
4
SCK
5
BUSY
GND
SB
6
CNV
FAULT
SC
A
V
L
MISOA MISOB
CSC
GND
GND
SA
B
V
CC
C
D
E
F
G
H
J
K
L
M
V
CC2
GND2 GND2
SA2
SB2
SC2
N
V
L2
MISOA2 MISOB2 V
L2
GND2 BUSYS
P
ON2
SS2
MOSI2 SCK2 BUSY2 CNV2
R
BGA PACKAGE
36-PIN (15mm
×
6.25mm
×
2.06mm)
T
JMAX
= 125°C,
θ
JA
= 36°C/W,
θ
JCTOP
= 27.5°C/W,
θ
JCBOTTOM
= 17.5°C/W
θ
JB
= 19.1°C/W, WEIGHT = 0.36g
ORDER INFORMATION
PART NUMBER
LTM2893CY#PBF
LTM2893IY#PBF
LTM2893HY#PBF
LTM2893CY-1#PBF
LTM2893IY-1#PBF
LTM2893HY-1#PBF
BGA
BGA
PACKAGE
TYPE
http://www.linear.com/product/LTM2893#orderinfo
PART MARKING
DEVICE
LTM2893Y
FINISH CODE
e1
MSL
RATING
3
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
BALL FINISH
SAC305 (RoHS)
SAC305 (RoHS)
LTM2893Y-1
e1
3
–40°C to 85°C
–40°C to 125°C
• Device temperature grade is indicated by a label on the shipping container.
• Pad or ball finish code is per IPC/JEDEC J-STD-609.
• Terminal Finish Part Marking:
www.linear.com/leadfree
• This product is not recommended for second side reflow. For more information, go
to
www.linear.com/BGA-assy
• Recommended BGA PCB Assembly and Manufacturing
Procedures:
www.linear.com/BGA-assy
• BGA Package and Tray Drawings:
www.linear.com/packaging
• This product is moisture sensitive. For more information, go to:
www.linear.com/BGA-assy
2
28931fb
For more information
www.linear.com/LTM2893
LTM2893/LTM2893-1
The
l
denotes the specifications which apply over the full specified
operating temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
L
= 3.3V, GND = 0V, V
CC2
= 5V, V
L2
= 3.3V, GND2
= 0V unless otherwise noted. (Note 9)
SYMBOL PARAMETER
Power Supplies
V
CC
I
CC
Operating Supply Range
Operating Supply Current
Operating Supply Current 1Msps, ADC
Conversion Rate
V
CC2
I
CC2
Isolated Operating Supply Range
Isolated Operating Supply Current
Isolated Operating Supply Current, 1Msps ADC
Conversion Rate
V
L
I
L
Logic Interface Supply Range
Logic Interface Supply Current
Logic Interface Supply Current, 1Msps
Conversion Rate
V
L2
I
L2
Isolated Interface Supply Range
Isolated Interface Supply Current
Isolated Interface Supply Current, 1Msps ADC
Conversion Rate
Digital Inputs and Digital Outputs (Logic Side)
V
IH
V
IL
High Level Input Voltage
Low Level Input Voltage
Digital Input Current (MOSI, SCK, CNV)
1.71V ≤ V
L
≤ 5.5V
1.71V ≤ V
L
≤ 5.5V
V
IN
= 0V to V
L
l
l
l
l
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
3.0
TYP
MAX
5.5
UNITS
V
mA
mA
V
mA
mA
V
µA
mA
V
µA
mA
Idle
20pF Loads, SCK = 100MHz
l
l
l
9
12
3.0
9
12
1.71
2
1.71
2.5
12
15
5.5
12
15
5.5
±200
5
5.5
±200
5
Idle
20pF Loads, SCK2 = 100MHz
l
l
l
Inputs and Outputs Static at GND or V
L
SCK = 100MHz, 20pF Load
l
l
l
Inputs and Outputs Static at GND2 or V
L2
SCK2 = 100MHz, 20pF Load
l
l
0.8 • V
L
0.2 • V
L
±1
±60
5
V
L
– 0.2
0.2
±1
–80
80
V
V
µA
µA
pF
V
V
µA
mA
mA
V
0.2 • V
L2
±60
±10
5
V
µA
µA
pF
V
0.2
–80
80
±15
±4
±4
V
mA
mA
kV
kV
kV
28931fb
Digital Input Current (SS,
CSC,
SA, SB, SC, ON) V
IN
= 0V to V
L
Digital Input Capacitance
Note 2
V
OH
V
OL
I
OZ
High Level Output Voltage
Low Level Output Voltage
High-Z Output Leakage Current MISOA, MISOB
Output Source Current (Short-Circuit)
Output Sink Current (Short-Circuit)
Digital Inputs and Digital Outputs (Isolated Side)
V
IH
V
IL
High Level Input Voltage
Low Level Input Voltage
Digital Input Current (ON2, BUSY2, BUSYS)
Digital Input Current (MISOA2, MISOB2)
Digital Input Capacitance
V
OH
V
OL
High Level Output Voltage
Low Level Output Voltage
Output Source Current (Short-Circuit)
Output Sink Current (Short-Circuit)
ESD Performance (Note 7)
Isolation Barrier
Logic Side I/O Pins
Isolated Side I/O Pins
From GND, V
L
, or V
CC
to GND2, V
L2
, or V
CC2
With Respect to GND, V
L
, or V
CC
With Respect to GND2, V
L2
, or V
CC2
1.71V ≤ V
L2
≤ 5.5V
1.71V ≤ V
L2
≤ 5.5V
V
IN
= 0V to V
L2
, ON2 = VL2
V
IN
= 0V to V
L2
Note 2
I
OUT
= –500µA, 1.71V ≤ V
L2
≤ 5.5V
I
OUT
= 500µA, 1.71V ≤ V
L2
≤ 5.5V
V
OUT
= 0V (Note 2)
V
OUT
= V
L2
(Note 2)
I
OUT
= –500µA, 1.71V ≤ V
L
≤ 5.5V
I
OUT
= 500µA, 1.71V ≤ V
L
≤ 5.5V
SS
= V
L
V
OUT
= 0V (Note 2)
V
OUT
= V
L
(Note 2)
l
l
l
l
l
l
l
0.8 • V
L2
l
l
V
L2
– 0.2
For more information
www.linear.com/LTM2893
3
LTM2893/LTM2893-1
The
l
denotes the specifications which apply over the full specified
operating temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
L
= 3.3V, GND = 0V, V
CC2
= 5V, V
L2
= 3.3V, GND2
= 0V unless otherwise noted. (Note 9)
SYMBOL
t
CNVH
t
BUSYLH
t
DCNV
t
CNV2H
PARAMETER
CNV Pulse Width
CNV↑ to BUSY↑ Delay
CNV↑ to CNV2↑ Delay (Aperture Delay)
CNV2 Pulse Width
CNV to CNV2 Rising Edge Jitter RMS
Minimum Low Time for CNV
SPI Timing
t
QUIET
t
SCK
t
SCKH
t
SCKL
t
SCK2
t
SCK2H
t
SCK2L
t
HDMISO2
t
DMISO
t
SUMISO2
t
HMISO
SCK or
SS↑
Space to CNV↑
SCK Input Period
SCK Input High Time
SCK Input Low Time
SCK2 Output Period
SCK2 Output High Time
SCK2 Output Low Time
MISOA2, MISOB2 Data Hold Time from
SCK2↑
LTM2893
LTM2893-1, Configuration Register = 0x9F
SCK2 Frequency 100MHz LTM2893 (Note 3)
SCK2 Frequency 100MHz LTM2893-1 (Note 3)
(Note 2)
(Note 2)
SCK2 Frequency 100MHz (Notes 3, 8)
(Note 2)
(Note 2)
(Note 2)
l
l
l
l
l
l
l
l
l
l
l
l
l
l
SWITCHING CHARACTERISTICS
Conversion Start
CONDITIONS
l
l
l
MIN
20
TYP
MAX
UNITS
ns
40
12
20
35
30
100
20
320
10
10
4
4
9.5
4
4
1
5
7.5
8
9.5
10
10.8
1185
21
33
52
80
ns
ns
ns
ns
ps
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
(Config. SCK2 Frequency ≥ 40MHz)
(Config. SCK2 Frequency ≤ 33MHz)
(Note 7)
l
l
MISOA, MISOB Data Valid Delay from SCK↑ C
L
= 20pF, V
L
= 5.5V (Note 2)
SCK2 Frequency = 100MHz or 66MHz or from C
L
= 20pF, V
L
= 2.5V (Note 2)
SCK↓ SCK2 Frequency ≤ 50MHz
C
L
= 20pF, V
L
= 1.71V (Note 2)
MISOA2, MISOB2, Setup Time to SCK2↑
(Note 2)
MISOA, MISOB Data Remains Valid Delay
C
L
= 20pF (Note 2)
from SCK↑
SCK2 Frequency = 100MHz or 66MHz or from
SCK↓ SCK2 Frequency ≤ 50MHz
MISOA, MISOB Data Valid Delay from
SS↓
SS↓
Delay to SCK↑
BUSY↓ Delay to SCK↑
BUSY2↓ Delay to
SS2↓
SCK2 Frequency 100MHz
SCK2 Frequency 100MHz
SCK2 Frequency 100MHz (Note 8) LTM2893-1
SCK2 Frequency 100MHz
CRCENA Bit = 0
CRCENA Bit = 1
LTM2893-1 or Configuration Port Write (Note 2)
LTM2893-1 or Configuration Port Write (Note 2)
LTM2893-1
SS2↓
Delay to SCK2↑
Bus Relinquish Time After
SS↑
Last SCK↑ to
SS↑
Last SCK2↑ to
SS2↑
SS↑
to
SS↓
Space
C
L
= 20pF
SCK2 Frequency 100MHz (Note 8), LTM2893-1
SS
= 0V, SCK2 Frequency 100MHz
(Notes 9, 10)
MISOA, MISOB Data Valid Delay from BUSY↓
SS
= 0V, LTM2893
1.8
2
t
DMISOSSF
t
SSFSCK
t
BUSYFSCKR
t
BUSY2FSS2F
t
SS2FSCK2
t
DIS
t
SCKSSDIS
t
SCK2SSDIS
l
l
l
l
l
l
l
l
l
l
10
10
20
15
15
15
20
8
60
225
35
100
33
35
1185
1185
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
t
BUSY2FBUSYF
BUSY2↓ to BUSY↓
t
SUMOSI
t
HDMOSI
t
SS2FMOSI2
MOSI Setup to SCK↑
MOSI Hold Time to SCK↑
SS2↓
to MOSI2 Valid
l
l
l
1.5
1
8
ns
28931fb
4
For more information
www.linear.com/LTM2893
LTM2893/LTM2893-1
The
l
denotes the specifications which apply over the full specified
operating temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
L
= 3.3V, GND = 0V, V
CC2
= 5V, V
L2
= 3.3V, GND2
= 0V unless otherwise noted. (Note 9)
SYMBOL
t
DMOSI2
t
HMOSI2
PARAMETER
MOSI2 Data Valid Delay from SCK2↓
CONDITIONS
LTM2893-1 C
L
= 20pF, V
L
= 5.5V (Note 2)
C
L
= 20pF, V
L
= 2.5V (Note 2)
C
L
= 20pF, V
L
= 1.71V (Note 2)
LTM2893-1 (Note 2)
Note 7, C
L
= 20pF
Note 7, C
L
= 20pF
SCK2 Frequency 100MHz
SCK2 Frequency 100MHz
CRCENA = 0
CRCENA = 1
C
L
= 20pF, 1.71V ≤ (V
L
and V
L2
) ≤ 5.5V
C
L
= 20pF, 1.71V ≤ (V
L
and V
L2
) ≤ 5.5V
l
l
l
l
l
l
l
l
SWITCHING CHARACTERISTICS
MIN
TYP
1.5
MAX
4.0
4.0
4.5
UNITS
ns
ns
ns
ns
ps
ps
MOSI2 Data Remains Valid from SCK2↓
BUSY, MISOA, MISOB Rise/Fall Time
CNV2,
SS2,
MOSI2, SCK2 Rise/Fall Time
0.5
500
500
20
20
60
320
40
80
10
150
20
1185
1185
Configuration Port
t
CSCFSCK
t
CSCRSCK
t
CSCSPACE
CSC↓
Delay to SCK↑
SCK↑ to
CSC↑
CSC↑
Delay to
CSC↓
ns
ns
ns
ns
ns
ns
Select Signals (SA, SB, SC, SA2, SB2, and SC2)
Propagation Delay
Rise/Fall Time
ISOLATION CHARACTERISTICS
SYMBOL
V
ISO
PARAMETER
Rated Dielectric Insulation Voltage
(Notes 4, 5, 6)
Common Mode Transient Immunity
1 Second
T
A
= 25°C.
MIN
6000
7200
50
100
TYP
MAX
UNITS
V
RMS
V
RMS
kV/µs
CONDITIONS
1 Minute, Derived from 1 Second
(Note 2) V
CC
= V
L
= ON = 5V to GND, V
CC2
= V
L2
= ON2 = 5V to GND2, 1000V in 20ns Transient
Between GND and GND2
(Note 2)
V
PD
= 1830V
PEAK
(Note 4)
IEC 60112 (Note 2)
IEC 60112 (Note 2)
(Note 2)
(Notes 2, 4)
(Notes 2, 4)
(Note 2)
V
IORM
Maximum Working Insulation Voltage
Partial Discharge
1000
690
5
600
0.017
0.2
1
5
3
9.2
V
PEAK
, V
DC
V
RMS
pC
V
RMS
mm
mm
TΩ
pF
mm
CTI
DTI
Comparative Tracking Index
Depth of Erosion
Distance Through Insulation
Input to Output Resistance
Input to Output Capacitance
Creepage Distance
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Guaranteed by design, not production tested.
Note 3:
Guaranteed by other measured parameters and is not directly tested.
Note 4:
Device considered a 2-terminal device. Measurement between
groups of pins A1 through C6 shorted together and pins N1 through R6
shorted together.
Note 5:
The rated dielectric insulation voltage should not be interpreted as
a continuous voltage rating.
Note 6:
In accordance with UL1577, each device is proof tested for the
6000V
RMS
rating by applying an RMS voltage multiplied by an acceleration
factor of 1.2 for one second.
Note 7:
Evaluated by Design, not production tested.
Note 8:
See Table 5 for minimum and maximum timing specifications
affected by the selection of SCK2 frequencies in the configuration register.
Note 9:
All currents into device pins are positive; all currents out of device
are negative. All voltages are referenced to their corresponding ground
unless otherwise specified.
Note 10:
See Table 2 for delay requirements between falling edge of BUSY
and SCK for large word lengths.
Note 11:
Continuous operation above specified maximum operating
junction temperature may result in device degradation or failure.
28931fb
For more information
www.linear.com/LTM2893
5
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