1
dc1791afa
DEMO MANUAL DC1791A
Description
LTM2887
SPI/Digital or I
2
C µModule Isolator
with Dual Adjustable 5V Regulators
Demonstration circuit 1791A is a serial peripheral interface
bus (SPI) or inter-IC bus (I
2
C) µModule isolator with dual
adjustable 5V regulators featuring the
LTM
®
2887
. The demo
circuit features an EMI optimized circuit configuration and
printed circuit board layout. All components are integrated
into the µModule isolator. The demo circuit operates
from a single external supply on V
CC
. The part generates
L
, LT, LTC, LTM, µModule, Linear Technology and the Linear logo are registered trademarks of
Linear Technology Corporation. All other trademarks are the property of their respective owners.
perForMAnce sUMMArY
operAting principles
output voltages on V
CC2
and V
L2
which may be adjusted
by external programming resistors. It communicates all
necessary signaling across the isolation barrier through
LTC’s isolator µModule technology.
Design files for this circuit board are available at
http://www.linear.com/demo
(T
A
= 25°C)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
Input Supply Range
LTM2887-3
3.0
3.3
3.6
V
LTM2887-5
4.5
5.0
5.5
V
V
CC2
Regulated Output Voltage
4.75
5
5.25
V
Adjustable Output Voltage Range
0.6
5.5
V
Internal Current Limit
∆V
CC2
= –5%
110
mA
V
L2
Regulated Output Voltage
4.75
5
5.25
V
Adjustable Output Voltage Range
1.62
5.5
V
Internal Current Limit
∆V
L2
= –5%
110
mA
f
MAX
Maximum Data Rate
DI1
→
O1, Ix
→
DOx, CL = 15pF
20
MHz
LTM2887-S, Bidirectional Communication
LTM2887-S, Unidirectional Communication
4
8
MHz
MHz
LTM2883-I
400
kHz
V
IORM
Maximum Working Insulation Voltage
GND to GND2
560
V
DC
400
V
RMS
Common Mode Transient Immunity
30
kV/µs
The LTM2887 contains an isolated DC/DC conversion
system with multiple LDOs to deliver power to the two
output voltage rails from V
CC
. Isolation is maintained by
the separation of GND and GND2 where significant operat-
ing voltages and transients can exist without affecting the
operation of the LTM2887. The logic side ON pin enables
or shuts down the LTM2887. All logic side signals are
referenced to the logic supply pin V
L
. The LTM2887 is
available in two data bus configurations, SPI (–S) or I
2
C
(–I), and with two input voltage ranges, 3.0 to 3.6 volts
(–3) or 4.5 to 5.5 volts (–5).
