Datasheet

Test Outputs
25-Pin Male
DSUB
External BUF22821
Analog Power Supply
T1
V Supply
(V Power Supply)
DUT
SD
I C Interface
2
I C A0 Address
Jumper
2
TP1
Test Point
Header
J1
BUF22821
www.ti.com BUF22821EVM-USB Hardware Setup
2.1 Theory of Operation for BUF22821 Hardware
Figure 3 shows the BUF22821 test board hardware setup. The functionality of the PCB is such that it
provides connections to the I
2
C™ and general-purpose inputs/outputs (GPIOs) on the USB_DIG_Platform
board. It also provides connection points for external connections of the shunt voltage, bus voltage, and
ground.
Figure 3. BUF22821EVM-USB Board Block Diagram
2.2 Signal Definitions of J1 (25-Pin Male DSUB)
Table 3 shows the various signals connected to J1 on the BUF22821 test board.
Table 3. J1 Signal Definition for BUF22821EVM-USB
Pin No on U1 Signal BUF22821 Pin
1 N/C No connection
2 N/C No connection
3 N/C No connection
4 N/C No connection
5 N/C No connection
6 N/C No connection
7 N/C No connection
8 N/C No connection
9 I2C_SCK No connection
10 I2C_SDA2 No connection
11 N/C No connection
12 I2C_SCK_ISO
I
2
C clock signal (SCL) channel 1; can be
disconnected using a switch
13 I2C_SDA_ISO
I
2
C data signal (SDA) channel 1; can be
disconnected using a switch
14 N/C No connection
15 N/C No connection
16 N/C No connection
17 V
DUT
Switched 3-V/5-V power
(1)
18 V
CC
No connection
19 N/C No connection
20 N/C No connection
21 GND Common ground connection
22 SPI_SCK No connection
23 SPI_CS1 No connection
24 SPI_DOUT1 No connection
25 SPI_DIN1 No connection
(1)
When power is switched off, digital I/O is also switched off.
5
SBOU117–September 2011 BUF22821EVM-USB Evaluation Board and Software Tutorial
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