SNLS491B July   2014  – February 2015 DS125BR820

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Electrical Characteristics — Serial Bus Interface DC Specifications
    7. 6.7 Serial Bus Interface Timing Specifications
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
      1. 7.2.1 Functional Datapath Blocks
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
      1. 7.4.1 Pin Control Mode:
      2. 7.4.2 Slave SMBus Mode:
      3. 7.4.3 SMBus Master Mode
    5. 7.5 Signal Conditioning Settings
    6. 7.6 Programming
      1. 7.6.1 EEPROM Register Map for Single Device
    7. 7.7 Register Maps
      1. 7.7.1 Transfer Of Data Via The SMBus
      2. 7.7.2 SMBus Transactions
      3. 7.7.3 Writing a Register
      4. 7.7.4 Reading a Register
      5. 7.7.5 Detailed Register Map
  8. 8 Applications and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Signal Integrity in 40G-CR4/KR4/SAS/SATA/PCIe Applications
      2. 8.1.2 Signal Integrity in 40G-SR4/LR4 Applications
      3. 8.1.3 Rx Detect Functionality in 40G-CR4/KR4/SAS/SATA Applications
    2. 8.2 Typical Applications
      1. 8.2.1 Generic High Speed Repeater
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Performance Plots
      2. 8.2.2 Front Port Applications (40G-CR4/SR4/LR4)
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Performance Plots
      3. 8.2.3 PCIe Board Applications (PCIe Gen-3)
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Design Procedure
        3. 8.2.3.3 Application Performance Plots
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Trademarks
    2. 11.2 Electrostatic Discharge Caution
    3. 11.3 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

5 Pin Configuration and Functions

54-Pin WQFN
Package NJY
Top View
terminals.gif
A.

NOTE:

Above 54-lead WQFN graphic is a TOP VIEW, looking down through the package.

Pin Functions(1)

PIN I/O, TYPE PIN DESCRIPTION
NAME NO.
DIFFERENTIAL HIGH SPEED I/O
INB_0+, INB_0- ,
INB_1+, INB_1-,
INB_2+, INB_2-,
INB_3+, INB_3-		 1, 2
3, 4
5, 6
7, 8		 I, CML Inverting and non-inverting CML differential inputs to the equalizer.
On-chip 50 Ω termination resistor connects INB_n+ to VDD and INB_n- to VDD depending on the state of RXDET. See Table 2.
AC coupling required on high-speed I/O
OUTB_0+, OUTB_0-,
OUTB_1+, OUTB_1-,
OUTB_2+, OUTB_2-,
OUTB_3+, OUTB_3-		 45, 44
43, 42
40. 39
38, 37		 O, CML Inverting and non-inverting 50 Ω driver outputs. Compatible with AC coupled CML inputs.
AC coupling required on high-speed I/O
INA_0+, INA_0- ,
INA_1+, INA_1-,
INA_2+, INA_2-,
INA_3+, INA_3-		 10, 11
12, 13
15, 16
17, 18		 I, CML Inverting and non-inverting CML differential inputs to the equalizer.
On-chip 50 Ω termination resistor connects INA_n+ to VDD and INA_n- to VDD depending on the state of RXDET. See Table 2.
AC coupling required on high-speed I/O
OUTA_0+, OUTA_0-,
OUTA_1+, OUTA_1-,
OUTA_2+, OUTA_2-,
OUTA_3+, OUTA_3-		 35, 34
33, 32
31, 30
29, 28		 O, CML Inverting and non-inverting 50 Ω driver outputs. Compatible with AC coupled CML inputs.
AC coupling required on high-speed I/O
CONTROL PINS — SHARED (LVCMOS)
ENSMB 48 I, 4-LEVEL,
LVCMOS		 System Management Bus (SMBus) Enable Pin
Tie 1 kΩ to VDD = Register Access SMBus Slave Mode
FLOAT = Read External EEPROM (SMBus Master Mode)
Tie 1 kΩ to GND = Pin Mode
ENSMB = 1 (SMBus SLAVE MODE)
SCL 50 I, LVCMOS,
O, OPEN Drain		 In SMBus Slave Mode, this pin is the SMBus clock I/O. Clock input or open drain output.
External 2 kΩ to 5 kΩ pull-up resistor to VDD or VIN recommended as per SMBus interface standards(2)
SDA 49 I, LVCMOS,
O, OPEN Drain		 In both SMBus Modes, this pin is the SMBus data I/O. Data input or open drain output.
External 2 kΩ to 5 kΩ pull-up resistor to VDD or VIN recommended as per SMBus interface standards(2)
AD0-AD3 54, 53, 47, 46 I, LVCMOS SMBus Slave Address Inputs. In both SMBus Modes, these pins are the user set SMBus slave address inputs.
External 1 kΩ pull-up or pull-down recommended.
Note: In Pin Mode, AD2 must be tied via external 1 kΩ to GND.
RESERVED2 21 I, 4-LEVEL,
LVCMOS 		Reserved
For applications requiring Signal Detect status register read-back:
● Leave Pin 21 floating.
● Write Reg 0x08[2] = 1 if Pin 21 is floating.
Otherwise, tie Pin 21 via external 1 kΩ to GND (External 1 kΩ to VDD is also acceptable).
RESERVED3 19 I, 4-LEVEL,
LVCMOS 		Reserved
This input may be left floating, tied via 1 kΩ to VDD, or tied via 1 kΩ to GND.
ENSMB = Float (SMBus MASTER MODE)
SCL 50 I, LVCMOS,
O, OPEN Drain		 Clock output when loading EEPROM configuration, reverting to SMBus clock input when EEPROM load is complete (ALL_DONE = 0).
External 2 kΩ to 5 kΩ pull-up resistor to VDD or VIN recommended as per SMBus interface standards(2)
SDA 49 I, LVCMOS,
O, OPEN Drain		 In both SMBus Modes, this pin is the SMBus data I/O. Data input or open drain output.
External 2 kΩ to 5 kΩ pull-up resistor to VDD or VIN recommended as per SMBus interface standards(2)
AD0-AD3 54, 53, 47, 46 I, LVCMOS SMBus Slave Address Inputs. In both SMBus Modes, these pins are the user set SMBus slave address inputs.
External 1 kΩ pull-up or pull-down recommended.
Note: In Pin Mode, AD2 must be tied via external 1 kΩ to GND.
READ_EN 26 I, LVCMOS A logic low on this pin starts the load from the external EEPROM(3).
Once EEPROM load is complete (ALL_DONE = 0), this pin functionality remains as READ_EN. It does not revert to an SD_TH input.
RESERVED2 21 I, 4-LEVEL,
LVCMOS 		Reserved
For applications requiring Signal Detect status register read-back:
● Leave Pin 21 floating.
● Write Reg 0x08[2] = 1 if Pin 21 is floating.
Otherwise, tie Pin 21 via external 1 kΩ to GND (External 1 kΩ to VDD is also acceptable).
RESERVED3 19 I, 4-LEVEL,
LVCMOS 		Reserved
This input may be left floating, tied via 1 kΩ to VDD, or tied via 1 kΩ to GND.
ENSMB = 0 (PIN MODE)
EQA
EQB		 20
46		 I, 4-LEVEL,
LVCMOS 		EQA and EQB pins control the level of equalization for the A-channels and B-channels, respectively. The pins are defined as EQA and EQB only when ENSMB is de-asserted (low). Each of the four A-channels have the same level unless controlled by the SMBus control registers. Likewise, each of the four B-channels have the same level unless controlled by the SMBus control registers.
When the device operates in Slave or Master Mode, the SMBus registers independently control each lane, and the EQB pin is converted to an AD3 input. See Table 4.
VODB0
VODB1		 53
54		 I, 4-LEVEL,
LVCMOS		 VODB[1:0] controls the output amplitude of the B-channels. The pins are defined as VODB[1:0] only when ENSMB is de-asserted (low). Each of the four B-channels have the same level unless controlled by the SMBus control registers. When the device operates in Slave or Master Mode, the SMBus registers provide independent control of each lane, and VODB[1:0] pins are converted to AD0, AD1 inputs. See Table 5.
VODA0
VODA1		 49
50		 I, 4-LEVEL,
LVCMOS 		VODA[1:0] controls the output amplitude of the A-channels. The pins are defined as VODA[1:0] only when ENSMB is de-asserted (low). Each of the four A-channels have the same level unless controlled by the SMBus control registers. When the device operates in Slave or Master Mode, the SMBus registers provide independent control of each lane and the VODA[1:0] pins are converted to SCL and SDA. See Table 5.
AD2 47 I, LVCMOS Reserved in Pin Mode (ENSMB = 0)
This input must be tied via external 1 kΩ to GND.
SD_TH 26 I, 4-LEVEL,
LVCMOS 		Controls the internal Signal Detect Status Threshold value when in Pin Mode and SMBus Slave Mode. This pin is to be used for system debugging only. See Table 3 for more information.
For final designs, input can be left floating, tied via 1 kΩ to VDD, or tied via 1 kΩ to GND.
RESERVED2 21 I, 4-LEVEL,
LVCMOS 		Reserved
Tie via external 1 kΩ to GND (External 1 kΩ to VDD is also acceptable).
RESERVED3 19 I, 4-LEVEL,
LVCMOS 		Reserved
This input must be tied via external 1 kΩ to GND.
CONTROL PINS — BOTH PIN AND SMBUS MODES (LVCMOS)
RXDET 22 I, 4-LEVEL,
LVCMOS 		The RXDET pin controls the input enable function. Depending on the input level, a 50 Ω or >50 kΩ termination to the power rail is enabled. Pull up pin to VDD (2.5 V mode) or VIN (3.3 V mode) through 1 kΩ resistor to provide a 50 Ω termination to the power rail for normal operation.
See Table 2.
RESERVED1 23 I, 4-LEVEL,
LVCMOS 		Reserved
This input must be left floating.
VDD_SEL 25 I, FLOAT Controls the internal regulator
Float = 2.5 V mode
Tie to GND = 3.3 V mode
PWDN 52 I, LVCMOS Tie High = Low power - Power Down
Tie to GND = Normal Operation
See Table 2.
ALL_DONE 27 O, LVCMOS Valid Register Load Status Output
HIGH = External EEPROM load failed or incomplete
LOW = External EEPROM load passed
POWER
VIN 24 Power In 3.3 V mode, feed 3.3 V to VIN
In 2.5 V mode, leave floating.
VDD 9, 14, 36, 41, 51 Power Power Supply for CML and Analog Pins
2.5 V mode, connect to 2.5 V
3.3 V mode, connect 0.1 µF cap to each VDD Pin and GND
See Power Supply Recommendations for proper power supply decoupling .
GND DAP Power Ground pad (DAP - die attach pad).
(1) LVCMOS inputs without the “Float” conditions must be driven to a logic low or high at all times or operation is not ensured.
Input edge rate for LVCMOS/FLOAT inputs must be faster than 50 ns from 10–90%.
For 3.3 V mode operation, VIN pin input = 3.3 V and the logic "1" or "high" reference for the 4-level input is 3.3 V.
For 2.5 V mode operation, VDD pin output= 2.5 V and the logic "1" or "high" reference for the 4-level input is 2.5 V.
(2) SCL and SDA pins can be tied either to 3.3 V or 2.5 V, regardless of whether the device is operating in 2.5 V mode or 3.3 V mode.
(3) When READ_EN is low, the device attempts to load EEPROM. If EEPROM cannot be loaded successfully, for example due to an invalid or blank hex file, the DS125BR820 hangs indefinitely in an unknown state. ALL_DONE pin remains high in this situation.