Datasheet
Switch Connection Overview
www.ti.com
3 Switch Connection Overview
Table 2. Connection and Control Description
Component Name Function
IN_B2+, IN_B2-,
IN_B3+, IN_B3-,
J1 to J8 High-speed differential inputs
IN_A0+, IN_A0-,
IN_A1+, IN_A1-,
OUT_B2+, OUT_B2-,
OUT_B3+, OUT_B3-,
J9 to J16 High-speed differential outputs
OUT_A0+, OUT_A0-,
OUT_A1+, OUT_A1-,
J19 VIN or VDD DC Power - VIN or VDD to DS125BR401SQ
J20 VIN or VDD Jumper – VIN or VDD to VIH power
Optional SMBUS access pins.
J17 SDA, SCL
See the datasheet for additional information on SMBUS.
J18 EEPROM Optional socket for EEPROM
EQB[1:0] or PIN MODE – EQ control for channel B inputs
SW1
AD[3:2] SMBUS MODE – AD[3:2] device address bits
ENSMB = LOW – PIN MODE
ENSMB = HIGH – SMBUS (slave mode)
SW2 ENSMB
ENSMB = FLOAT – SMBUS (master mode – load configuration from
EEPROM)
SW3 DEMA[1:0] PIN MODE – DE control for channel A outputs
SW4 SDA/SCL “ON” position connects SDA and SCL lines to the device pin.
DEMB[1:0] or PIN MODE – DE control for channel B outputs
SW5
AD[1:0] SMBUS MODE – AD[1:0] device address bits
SD_TH – Signal detect threshold level (FLOAT = Default level)
SW6 SD_TH and LPBK - RES
LPBK function for BR401 only (FLOAT = Normal operation)
VDD_SEL and VDD_SEL – Enable or disable the internal 3.3V to 2.5V regulator.
SW7
RESET RESET – Enable or disable the device (LOW – enable)
SW8 EQA[1:0] PIN MODE – EQ control for channel A inputs
INPUT_EN – Enable or disable the internal 50 ohm to VDD terminations
MODE – Tie 1kΩ to GND = GEN 1,2 and SAS 1,2
INPUT_EN and
SW9 Float = Auto Mode Select (for PCIe and SAS-3)
MODE
Tie 20kΩ to GND = SAS-3 and GEN-3 without De-emphasis
Tie 1kΩ to VDD = SAS-3 and GEN-3 with De-emphasis
ENSMB = FLOAT – SMBUS (master mode – load configuration from
EEPROM)
SW6: SD_TH becomes the READ_EN pin.
To start the loading at power up, set SW6 pin 3 to “ON” position (pull to
SW10 READ_EN
GND).
To manually control the start, set SW6 pin 1 to “ON” position (pull to VDD)
and push the SW10 button for the high to low transition to start the loading.
When the loading is complete the LED – D1 light should turn OFF.
6
DS125BR401EVM Evaluation Kit SNLU121–November 2012
Submit Documentation Feedback
Copyright © 2012, Texas Instruments Incorporated