Evm Schematic And Pcb; Figure 6-1. Iso1644Dwevm Schematic - Texas Instruments ISO1644DWEVM User Manual

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6 EVM Schematic and PCB

The ISO1644DW isolated I
be configured for use with an ISO1642DW or ISO1643DW. Each signal line (SDAx, SCLx) is configured with a
3.3-kΩ pullup resistor (R1 to R4) to the corresponding power supply (VCCx). These resistors may be replaced
with 0805 resistors of other values per the application requirements. For insight on calculating appropriate pullup
2
resistor values for I C buses, please refer to the
ISO164x devices are designed to sink different amounts of current on side 1 and side 2, be careful to
choose resistors that keep I
R1 to R4.
Signal pins may be tied directly to ground using the header pins (J1 on side 1; J2 on side 2) to simulate a
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device pulling the I C line low. While not being actively driven low, the lines will be pulled up through the included
pullup resistors. Signal lines should not be tied directly to a supply voltage without a pullup resistor to
limit input current. These jumpers also provide input /output signal access, including for oscilloscope probes, to
each pin.
Ensure that SDAx and SCLx signal lines are not tied directly to VCCx. A current-limiting pullup resistor
is required, and populated by default, to limit current in the cases where the device pins drive a
low-voltage.
Figure 6-1 shows the schematic diagram for this EVM, and
board (PCB) layout.
VCC1 TP1 TP2 TP3 TP4
J1
1 2
3 4
GND1
5 6
7 8
9 10
11 12
13 14
GND1
SLLU329 – JUNE 2021
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2
C EVM comes with an ISO1644DW installed in place of U1. This EVM can also
I2C Bus Pullup Resistor Calculation
and I within the recommended operating range if replacing resistors
OL1 OL2
VCC1
C1 C2 C3
DNP
10uF 1µF 100nF
GND1
TP5 TP6 TP7 TP8
VCC1 VCC1
GND1 R1 R2
1
3.3k 3.3k
6
3
4
5
7
2
8
GND1

Figure 6-1. ISO1644DWEVM Schematic

Copyright © 2021 Texas Instruments Incorporated
Note
Note
Figure 6-2 and Figure 6-3
VCC2
C6 C5
DNP
100nF 1µF
GND2
VCC2 VCC2
U1
R3 R4
16
VCC1 VCC2
3.3k 3.3k
11
SCL1 SCL2
14
SDA1 SDA2
13
INA OUTA
12
INB OUTB
10
OUTC INC
9
GND1 GND2
15
GND1 GND2
ISO1644DWR
GND2
ISO1644DWEVM Reinforced Isolated I
EVM Schematic and PCB
application report.
show the printed circuit
C4
10uF
TP9 TP10 TP11 TP12 TP13 TP14 TP15 TP16 VCC2
GND2
GND2
2
C With GPIOs Evaluation Module
J2
1 2
3 4
5 6
7 8
9 10
11 12
13 14
GND2
5