LTM2895
100MHz Isolated
DAC SPI Serial Interface
FEATURES
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DESCRIPTION
The
LTM
®
2895
is a high speed isolated µModule
®
(micro-
module) SPI interface with DAC control signals designed
to isolate LTC’s family of general purpose DACs and to
isolate general purpose SPI interfaces. The LTM2895
works with DACs and general purpose devices that have
a mode (0, 0) SPI interface.
The interface enables fast data throughput, which makes
the LTM2895 ideally suited for a wide variety of applica-
tions. The high speed SPI-compatible serial port supports
1.71V to 5.5V logic supplies. The LTM2895 is targeted at
generic SPI and digital-to-analog converter applications.
The isolation barrier tolerates large voltage ground varia-
tions between the logic interface and the isolated side of
the LTM2895. Uninterrupted communication is maintained
during voltage transients greater than 50kV/µs.
All registered trademarks and trademarks are the property of their respective owners.
Isolated Interface: 6000V
RMS
for 1 Minute
CSA (IEC/UL) Approved, File #255632
100MHz SPI-Compatible I/O
Configurable SPI Word-Length: 8 to 32 Bits
Supports Two Isolated Chip Selects
Falling Edge Sensitive Low Jitter
LOAD
Three Isolated Control or Multiplexer 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 Interface Control
Industrial Process Control and Automation
Test and Measurement Equipment
Breaking Ground Loops
TYPICAL APPLICATION
LTC2642-16 DAC Isolation
3.3V
5V
i
8V
i
LT6654-5
V
IN
V
OUT
GND
V
DD
10k
V
L
V
CC
V
CC2
V
L2
5V
i
100k
LOAD2
SS2
SSB2
SCK2
MOSI2
MISO2
SA2
SB2
SC2
GND2
2895TA01
10µF
I
NV
LTC2642-16
V
OUT
CLR
GND
GND
GND
CONFIGURATION REGISTERS: WRITE 0x30H AND 0x83H
SETS SCK2 TO 33MHz AND WORDLENGTH TO 16-BIT
V
i
= ISOLATED VOLTAGE SUPPLY
For more information
www.linear.com/LTM2895
+
SCK
D
IN
–
ON
SYSINT
FLTINT
LOAD
CS
P
CS2
SCK
MOSI
MISO
CLR
ON
BUSY
FAULT
LOAD
SS
SSB
SCK
MOSI
MISO
SA
SB
SC
ON2
LTM2895
ISOLATION BARRIER
V
DD
REF
RFB
27pF
8V
i
LT1468
–8V
i
OUT
CS
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1
LTM2895
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltages
V
L
– GND .................................................−0.3V to 6V
V
CC
– GND ...............................................−0.3V to 6V
Isolated Supply Voltages
V
L2
– GND2 .............................................−0.3V to 6V
V
CC2
– GND2............................................−0.3V to 6V
Logic Signals
ON,
LOAD,
BUSY, SA, SB, SC,
SS, SSB
SCK, MOSI, MISO ................ GND – 0.3V to V
L
+ 0.3V
FAULT
............................................... GND – 0.3V to 6.3V
Isolated Signals
SS2, SSB2,
MISO2, ON2,
LOAD2,
SCK2
SA2, SB2, SC2, MOSI2 .....GND2 – 0.3V to V
L2
+ 0.3V
Operating Temperature Range (Note 10)
LTM2895C ............................................... 0°C to 70°C
LTM2895I ............................................–40°C to 85°C
LTM2895H .........................................−40°C to 125°C
Storage Temperature Range .................. –55°C to 125°C
Maximum Internal Operating Temperature............ 125°C
Peak Body Reflow Temperature ............................ 260°C
PIN CONFIGURATION
TOP VIEW
6
LOAD
FAULT
GND
SSB
GND
MISO
V
L
SC
SB
SA
GND
GND
V
CC
SC2
SB2
SA2
GND2
DNC
GND2
SSB2
LOAD2
DNC
SCK2
5
BUSY
4
SCK
3
MOSI
GND2 MOSI2
SS2
ON2
2
SS
GND2 MISO2
V
CC2
V
L2
1
ON
A
B
C
D
E
F
G
H
J
K
L
M
N
P
R
BGA PACKAGE
36-LEAD (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
LTM2895CY#PBF
LTM2895IY#PBF
LTM2895HY#PBF
BGA
PACKAGE
TYPE
http://www.linear.com/product/LTM2895#orderinfo
PART MARKING*
BALL FINISH
SAC305 (RoHS)
DEVICE
LTM2895Y
FINISH CODE
e1
MSL
RATING
3
TEMPERATURE RANGE
(SEE NOTE 2)
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
• 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
• 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
2
2895fa
For more information
www.linear.com/LTM2895
LTM2895
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, Max
DAC Conversion Rate
V
CC2
I
CC2
Isolated Operating Supply Range
Isolated Operating Supply Current
Isolated Operating Supply Current, Max
DAC Conversion Rate
V
L
I
L
Logic Interface Supply Range
Logic Interface Supply Current
Logic Interface Supply Current, Max
Conversion Rate
V
L2
I
L2
Isolated Interface Supply Range
Isolated Interface Supply Current
Isolated Interface Supply Current, Max
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,
LOAD)
Digital Input Current (SS,
SSB,
SA, SB, SC, ON)
Digital Input Capacitance
V
OH
V
OL
High Level Output Voltage
Low Level Output Voltage
High-Z Output Leakage Current MISO
Output Source Current (Short-Circuit)
MISO, BUSY
Output Sink Current (Short-Circuit)
MISO, BUSY,
FAULT
Digital Inputs and Digital Outputs (Isolated Side)
V
IH
V
IL
High Level Input Voltage
Low Level Input Voltage
Digital Input Current (ON2)
Digital Input Current (MISO2)
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)
1.71V ≤ V
L2
≤ 5.5V
1.71V ≤ V
L2
≤ 5.5V
V
IN
= 0V to V
L2
V
IN
= 0V to V
L2
(Note 7)
I
OUT
=
−500μA,
1.71V ≤ V
L2
≤ 5.5V
I
OUT
= 500μA, 1.71V ≤ V
L2
≤ 5.5V
V
OUT
= 0V (Note 7)
V
OUT
= V
L2
(Note 7)
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ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
3.0
TYP
MAX
5.5
UNITS
V
mA
mA
V
mA
mA
V
µA
mA
V
µA
mA
Idle
l
9
12
3.0
9
12
1.71
3.3
2
1.71
3.3
2
12
15
5.5
12
15
5.5
±200
5
5.5
±200
5
32-Bit Write/1μs, 20pF Loads, SCK = 50MHz
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Idle
l
32-Bit Write/1μs, 20pF Loads, SCK = 50MHz
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Inputs and Outputs Static at GND or V
L
l
32-Bit Write/1μs, 20pF Loads, SCK = 50MHz
l
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Inputs and Outputs Static at GND2 or V
L2
l
32-Bit Write/1μs, 20pF Loads, SCK = 50MHz
l
1.71V ≤ V
L
≤ 5.5V
1.71V ≤ V
L
≤ 5.5V
V
IN
= 0V to V
L
,
SS
= V
L
V
IN
= 0V to V
L
(Note 7)
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 7)
V
OUT
= V
L
(Note 7)
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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
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0.8 • V
L2
0.2 • V
L2
±60
±10
5
V
L2
–
0.2
0.2
−80
80
V
V
μA
µA
pF
V
V
mA
mA
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For more information
www.linear.com/LTM2895
3
LTM2895
ESD PERFORMANCE
SYMBOL
PARAMETER
Isolation Barrier
Logic Side I/O Pins
Isolated Side I/O Pins
(Note 7)
CONDITIONS
From GND, V
L
, or V
CC
to GND2, V
L2
, or V
CC2
GND, V
L
, V
CC
GND2, V
L2
, V
CC2
MIN
TYP
±15
±4
±4
MAX
UNITS
kV
kV
kV
The
l
denotes specifications that apply over the full specified operating
temperature range, otherwise specifications are at T
A
= 25°C, C
L
= 20pF, V
CC
= 5V, V
L
= 3.3V, GND = 0V, V
CC2
= 5V, V
L2
= 3.3V,
GND2 = 0V; unless otherwise noted.
SYMBOL
t
LOADL
t
DLYLOAD2
t
PWLOAD2
PARAMETER
LOAD
Low Pulse Width
LOAD↓
to
LOAD2↓
Delay (Aperture Delay)
LOAD2
Low Pulse Width
LOAD
to
LOAD2
Falling Edge Jitter RMS
LOAD
High Time
SPI Timing
t
SCK
t
SCKH
t
SCKL
t
SUMOSI
t
HMOSI
t
DLYSSLOAD
t
DMISO
t
DMISO
t
HMISO
t
HMISO
t
DMISOSSF
t
SCK2L
t
SUMISO2
t
HMISO2
t
HMOSI2
t
DMOSI2
t
SSFSCK
SCK Input Period
SCK Input High Time
SCK Input Low Time
MOSI Setup Time to SCK↑
MOSI Hold Time to SCK↑
SS
or
SSB
Delay to
LOAD↓
Quiet Time
MISO Data Valid Delay from SCK↑, SCK2
Selection > 50MHz
MISO Data Valid Delay from SCK↓, SCK2
Selection ≤ 50MHz
MISO Data Remains Valid Delay from SCK↑
MISO Data Remains Valid Delay from SCK↓
MISO Data Valid Delay from
SS↓
SCK2 Low Time
MISO2 Data Setup Time to SCK2↑
MISO2 Data Hold Time from SCK2↑
MOSI2 Data Remains Valid Delay from SCK2↓
MOSI2 Data Valid Delay from SCK2↓
SCK2 Frequency 50MHz (Notes 2, 8)
(Note 7)
(Note 7)
(Note 7)
V
L2
= 5.5V (Note 2)
V
L2
= 2.5V (Note 2)
V
L2
= 1.71V (Note 2)
SCK2 Frequency 50MHz (Note 8)
V
L
= 5.5V (Note 2)
V
L
= 2.5V (Note 2)
V
L
= 1.71V (Note 2)
V
L
= 5.5V (Note 2)
V
L
= 2.5V (Note 2)
V
L
= 1.71V (Note 2)
SCK2 ≥ 50MHz (Note 2)
SCK2 < 50MHz (Note 2)
SCK2 Frequency 50MHz (Note 8)
SCK2 Frequency 50MHz
SCK2 Frequency 50MHz
(Note 2)
(Note 2)
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SWITCHING CHARACTERISTICS
CONDITIONS
l
l
MIN
20
12
20
35
TYP
21
MAX
33
52
80
UNITS
ns
ns
ns
ns
ps
ns
(SCK2 Frequency ≥ 40MHz)
(SCK2 Frequency ≤ 33MHz)
(Note 7)
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l
30
l
100
20
9
9
1.5
1
100
5
7.5
8
9.5
7.5
8
9.5
2300
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
5
1.8
1.8
9.5
9.1
1.5
1
1
1.5
2
3.5
20
2300
ns
ns
ns
ns
ns
ns
ns
ns
ns
SS↓
or
SSB↓
Delay to SCK↑
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2895fa
For more information
www.linear.com/LTM2895
LTM2895
The
l
denotes specifications that apply over the full specified operating
temperature range, otherwise specifications are at T
A
= 25°C, C
L
= 20pF, V
CC
= 5V, V
L
= 3.3V, GND = 0V, V
CC2
= 5V, V
L2
= 3.3V,
GND2 = 0V; unless otherwise noted.
SYMBOL
t
DIS
t
SCKSSDIS
t
DLYSS2
t
SCKRSCK2F
t
DLYSCKMOSI2
t
SSSPACE
t
SS2FSCK2
t
SCK2SS2DIS
PARAMETER
Bus Relinquish Time After
SS↑
last SCK↑ to
SS↑
or
SSB↑
Delay from
SS
to
SS2
or
SSB
to
SSB2
Delay SCK↑ to SCK2↓
Delay SCK↑ to MOSI2 Valid
(Note 2)
SCK2 Frequency 50MHz
SCK2 Frequency 50MHz
(Note 7)
(Note 7)
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SWITCHING CHARACTERISTICS
CONDITIONS
l
MIN
l
TYP
MAX
35
2300
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
SCK2 Frequency 50MHz (Note 8)
SSB
to
SSB2
with DAC 2nd Channel
SCK2 Frequency 50MHz
25
22
22
24
1.5
60
45
32
500
500
t
DLYMOSI2SCK2
Setup MOSI2 to SCK2↑
SS↑
or
SSB↑
Space to
SS↓
or
SSB↓
SS2↓
or
SSB2↓
Delay to SCK2↑
Last SCK2↑ to
SS2↑
or
SSB2↑
MISO Rise/Fall Time
LOAD2, SS2, SSB2,
MOSI2, SCK2 Rise/Fall
Time
Select Signals
SA, SB, SC Propagation Delay
SA2, SB2, SC2 Rise/Fall Time
ps
ps
1.71V ≤ V
L
≤ 5.5V
1.71V ≤ V
L2
≤ 5.5V
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40
80
10
150
20
ns
ns
ISOLATION CHARACTERISTICS
SYMBOL
V
ISO
PARAMETER
Rated Dielectric Insulation Voltage
(Notes 4, 5, 6)
Common Mode Transient Immunity
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
1 Second
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 7)
(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
2895fa
For more information
www.linear.com/LTM2895
5
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