LTC5100 Datasheet, PDF (35/52 Pages) Linear Technology – 3.3V, 3.2Gbps VCSEL Driver

LTC5100
REGISTER DEFI ITIO S
Table 8. Register: SYS_CONFIG—System Configuration (I²C Command Code 0x10)
REGISTER
.BITFIELD
RESET VALUE
BIT
(BIN)
FUNCTION AND VALUES
.Reserved
15:8
.Cml_en
7
.Md_polarity
6
0
Current Mode Logic Enable
0: Floating Differential Input Termination: 100Ω Across IN⁺ and IN^–
1: CML Compatible Input Termination: 50Ω from IN⁺ to V_DD(HS) and from IN^– to V_DD(HS)
0
Monitor Diode Polarity
0: Cathode Connected to the MD Pin, Sinking Current from the Pin
1: Anode Connected to the MD Pin, Sourcing Current Into the Pin
.Ext_temp_en
5
0
External Temperature Enable
Selects the Source of Temperature Measurements for Temperature Compensation.
0: Internal Temperature Sensor
1: Externally Supplied Through the Serial Interface
.Power_down_en 4
1
Power Down Enable
Allow Power Reduction When the Transmitter is Disabled.
0: No Power Reduction When the Transmitter is Disabled.
1: Reduce Power Consumption When Transmitter is Disabled by Turning Off the High Speed Amplifiers.
.Apc_en
3
0
Automatic Power Control Enable
Select the Means of Controlling the Laser Bias Current.
0: Constant Current Control
1: Automatic Power Control Using Feedback from the Monitor Diode
.En_polarity
2
0
EN Pin Polarity
Set the Input Polarity of the EN Pin.
0: Active Low: A Logic Low Input Level Enables the Transmitter.
1: Active High: A Logic High Input Level Enables the Transmitter.
Note: In order to Enable the Transmitter, Both the EN Pin and Soft_en Bit Must be Asserted.
.Soft_en
1
0
Soft Transmitter Enable
Enables Transmitter Through the Serial Interface.
0: Disable the Transmitter
1: Enable the Transmitter (if the EN Pin is Active)
Note: In order to Enable the Transmitter, Both the EN Pin and Soft_en Bit Must be Asserted.
.Operating_mode 0
0
Digital Operating Control Mode
Select Whether the LTC5100 Operates Autonomously or Under External Control.
0: Standalone Operation: Configuration Parameters are Loaded from an External EEPROM at Power Up.
1: Externally Controlled Operation: Configuration Parameters are Set by an External Microprocessor or
Test Computer.
sn5100 5100fs
35