UG-400 Datasheet, PDF (8/20 Pages) Analog Devices – Plug and play system evaluation

UG-400
Hardware User Guide
ISOLATED I²C
The isolated I²C port is implemented using the ADuM1250 I²C
isolator and the ADuM5000 isoPower isolated dc-to-dc converter.
The ADuM1250 connects to TWI1 of the ADSP-BF548 and is
capable of functioning at a maximum frequency of 1 MHz.
Figure 7 shows a circuit diagram of the implementation of the
ADuM1250 and ADuM5000 on the ezLINX hardware.
The VDD1 pin (Pin 1)) of the ADuM1250 and the VDD1 pins
(Pin 1 and Pin 7) of the ADuM5000 are powered by 3.3 V. The
ADuM5000 generates an isolated 3.3 V, which is used to supply
power to the VDD2 pin (Pin 8) of the ADuM1250.
A 3-pin screw terminal connector, J22, is used for easy access to
the SDA (Pin 1 of J22), SCL (Pin 2 of J22), and I2C_ISO_GND
(Pin 3 of J22) signals.
The ADuM5000 contains isoPower technology that uses high
frequency switching elements to transfer power through the
transformer. Special care must be taken during PCB layout to
meet emissions standards. See the AN-0971 Application Note,
Recommendations for Control of Radiated Emissions with
isoPower Devices, for board layout recommendations.
3.3V
I2C_ISO_3.3V
SDA1
SCL1
3.3V
GND
U18
1
VDD1
2
3 ^SDA1
SCL1
4
GND1
ADuM1250
C172
0.01uF
GND
8
VDD2
7
SDA2 ₆
SCL2
5
GND2
I2C_ISO_GND
R73
120R
R74
120R
I2C_ISO_3.3V
I2C_ISO_GND
J22
1
2
3
SCREW_3
C173
0.01uF
I2C_ISO_GND
3.3V
U19
1
7 ^VDD1
VDD1
6
RCSEL
4
5 ^RCIN
RCOUT
GND
3.3V
2
8 ^GND1
GND1
ADuM5000
I2C_ISO_3.3V
10
VISO ₁₆
VISO
13
VSEL
3
NC1 ₁₁
NC2 ₁₂
NC3 ₁₄
NC4
9
GNDISO ₁₅
GNDISO
I2C_ISO_GND
I2C_ISO_3.3V
C168
10uF
C167
0.1uF
C166
0.1uF
C171
10uF
C170
0.1uF
C169
0.1uF
GND
I2C_ISO_GND
Figure 7. ADuM1250 and ADuM5000 Isolated I²C Implementation
Rev. 0 | Page 8 of 20