Quick Start Guide
Table 3-5. VOD Output Settings available in Pin Mode
VOD GAIN RELATIVE TO VID = 1.2 V
PP
SW3 (6-5-4), (3-2-1)
VODA[1:0]
Output
SW5 (6-5-4), (3-2-1)
Level
Input (V
PP
)
VODB[1:0]
(V
PP
)
6
5
4
3
2
1
1
0, 0
ON
OFF
OFF
ON
OFF
OFF
1.2
0.65
2
0, R
ON
OFF
OFF
OFF
ON
OFF
1.2
0.71
3
0, F
ON
OFF
OFF
OFF
OFF
ON
1.2
0.77
4
R, F
OFF
ON
OFF
OFF
OFF
OFF
1.2
0.83
5
F, R
OFF
OFF
OFF
OFF
ON
OFF
1.2
0.90
6
1, 0
OFF
OFF
ON
ON
OFF
OFF
1.2
1.00
NOTE:
The DS125BR820 channels are designed to be linear, ideal for small to moderate levels
of input attenuation or when TX FIR transparency is critical to system operation. There
are two additional levels of VOD available in SMBus modes. Refer to the DS125BR820
datasheet for more information.
7. SMBus slave mode – Set the EQ, VOD, VOD_DB level:
•
Set ENSMB = 1 (1 k
Ω
to VIH) by setting SW2 (3-2-1) = (OFF-OFF-
ON
).
•
Set SW4 switches 1 and 2 to the
ON
position so the SMBUS signals are connected.
•
Set SW3 switches 1 through 6 to the OFF position so they do not connect to the SDA and SCL
line.
•
Set SW1 and SW5 to configure the AD[3:0] pins. AD[3:0]=0000 sets device slave address (+ write
bit) = 0xB0.
•
Connect SDA, SCL and GND to J17.
•
All EQ, VOD, and VOD_DB levels can be set via SMBus registers in accordance to the register
map in the DS125BR820 datasheet.
8. SMBus master mode – Set the EQ, VOD, VOD_DB level:
•
Load a pre-programmed EEPROM in the J18 EEPROM slot. Note that the DS125BR820 can only
support EEPROM sizes ranging from 2K (256 Bytes) to 8K (1024 bytes). The EEPROM must also
be capable of an operating frequency up to 1 MHz.
•
Set ENSMB = FLOAT by setting SW2 (3-2-1) = (OFF-OFF-OFF).
•
Set SW4 switches 1 and 2 to the
ON
position so the SMBUS signals are connected.
•
Set SW3 switches 1 through 6 to the OFF position so they do not connect to the SDA and SCL
line.
•
Set SW1 and SW5 to configure the AD[3:0] pins. AD[3:0]=0000 sets device slave address (+ write
bit) = 0xB0.
•
Set SW6 and SW10 in accordance to the desired EEPROM load behavior:
–
To start loading EEPROM at power up, set SW6 pin 3 to
ON
(pull to GND).
–
To control the start manually, set SW6 pin 1 to
ON
(pull to VDD) and push the SW10 button for
the high-to-low transition to start loading EEPROM.
•
After a successful EEPROM load, the ALL_DONE pin on the DS125BR820 goes low and LED –
D1 turns off. Afterwards, the DS125BR820 releases control of the SDA/SCL line and all EQ, VOD,
and VOD_DB levels become controllable via SMBus slave registers in accordance to the SMBus
register map in the DS125BR820 datasheet.
11
SNLU166 – August 2014
DS125BR820EVM Configuration Overview
Copyright © 2014, Texas Instruments Incorporated