DS1874T+ Maxim Integrated Products, DS1874T+ Datasheet - Page 23

• Manufacturer Part Number: DS1874T+
• Description: IC CTLR SFP+ ANLG LDD 28-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Laser Diode Controllerr

Specifications of DS1874T+

• Number Of Channels: 1
• Voltage - Supply: 2.85 V ~ 3.9 V
• Current - Supply: 2.5mA
• Operating Temperature: -40°C ~ 95°C
• Package / Case: 28-WFQFN Exposed Pad
• Mounting Type: Surface Mount
• Number Of Outputs: 5
• Duty Cycle (max): 50 %
• Output Voltage: 0 V to 3.9 V
• Mounting Style: SMD/SMT
• Switching Frequency: 0 KHz to 400 KHz
• Operating Supply Voltage: 2.85 V to 3.9 V
• Supply Current: 2.5 mA to 10 mA
• Maximum Operating Temperature: + 95 C
• Fall Time: 300 ns
• Minimum Operating Temperature: - 40 C
• Rise Time: 300 ns
• Synchronous Pin: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 90-1874T+000

after the CSELOUT has been set to 1. Each operation
consists of 16-bit transfers (15-bit address/data, 1-bit
RWN). All data transfers are MSB first.
Write Mode (RWN = 0): The master generates 16 clock
cycles at SCLOUT in total. It outputs 16 bits (MSB first)
to the SDAOUT line at the falling edge of the clock. The
master closes the transmission by setting the
CSELOUT to 0.
Read Mode (RWN = 1): The master generates 16 clock
cycles at SCLOUT in total. It outputs 8 bits (MSB first)
to the SDAOUT line at the falling edge of the clock. The
SDAOUT line is released after the RWN bit has been
transmitted. The slave outputs 8 bits of data (MSB first)
at the rising edge of the clock. The master samples
SDAOUT at the falling edge of SCLOUT. The master
closes the transmission by setting the CSELOUT to 0.
Figure 15. 3-Wire Timing
CSELOUT
CSELOUT
SDAOUT
SDAOUT
SCLOUT
SCLOUT
15:9
BIT
7:0
8
WRITE MODE
READ MODE
SFP+ Controller with Digital LDD Interface
t
t
Address
L
L
NAME
RWN
A6
A6
Data
______________________________________________________________________________________
0
0
A5
A5
7-bit internal register address
0: write; 1: read
8-bit read or write data
1
1
t
t
DS
DS
A4
A4
2
2
DESCRIPTION
A3
A3
t
t
3
3
DH
DH
A2
A2
4
4
A1
A1
5
5
A0
A0
6
6
RWN
RWN
7
7
Figure 15 shows the 3-wire interface timing. Figure 16
shows the 3-wire state machine. See the 3-Wire Digital
Interface Specification table for more information.
The majority of the communication between the two
devices consists of bias adjustments for the APC loop.
After each temperature conversion, the laser modula-
tion setting must be updated. Status registers TXSTAT1
and TXSTAT2 are read between temperature updates
at a regular interval: t
Monitoring Characteristics table). The results are stored
in TXSTAT1 and TXSTAT2 (Table 02h, FCh–FDh).
The MAX3798/MAX3799 are manually controllable
using four registers in the DS1874: 3WCTRL,
ADDRESS, WRITE, and READ. Commands can be
manually issued while the DS1874 is in normal opera-
tion mode. It is also possible to suspend normal 3-wire
commands so that only manual operation commands
are sent (3WCTRL, Table 02h, Register F8h).
D7
8
8
D7
DS1874 and MAX3798/MAX3799
D6
9
9
D6
D5
10
10
D5
D4
3-Wire Interface Timing
11
11
D4
D3
12
12
RR
D3
D2
(see the Analog Voltage
13
13
Communication
D2
Normal Operation
Manual Operation
D1
14
14
D1
D0
15
15
D0
t
t
T
T
23