DS1874 datasheet(29/88 Pages) MAXIM

29 / 88 page

SFP+ Controller with Digital LDD Interface

______________________________________________________________________________________

Table 05h is empty by default. It can be configured to

contain the alarm- and warning-enable bytes from Table

01h, Registers F8h–FFh with the MASK bit enabled

(Table 02h, Register 89h). In this case Table 01h is

empty.

Table 06h contains a temperature-indexed LUT that

allows the APC set point to change as a function of

temperature to compensate for tracking error (TE). The

APC LUT has 36 entries that determine the APC setting

in 4°C windows between -40°C and +100°C.

Table 07h contains a temperature-indexed LUT for con-

trol of DAC1. The LUT has 36 entries that determine the

DAC setting in 4°C windows between -40°C and +100°C.

Table 08h contains a temperature-indexed LUT for con-

trol of DAC2. The LUT has 36 entries that determine the

DAC setting in 4°C windows between -40°C and +100°C.

Auxiliary Memory (device A0h) contains 256 bytes of

EE memory accessible from address 00h–FFh. It is

selected with the device address of A0h.

See the

plete details of each byte’s function, as well as for

read/write permissions for each byte.

Shadowed EEPROM

Many NV memory locations (listed within the

Descriptions section) are actually shadowed EEPROM

that are controlled by the SEEB bit in Table 02h,

The DS1874 incorporates shadowed-EEPROM memory

locations for key memory addresses that can be written

many times. By default the shadowed-EEPROM bit,

SEEB, is not set and these locations act as ordinary

EEPROM. By setting SEEB, these locations function like

SRAM cells, which allow an infinite number of write

cycles without concern of wearing out the EEPROM.

Setting SEEB also eliminates the requirement for the

EEPROM write time, tWR. Because changes made with

SEEB enabled do not affect the EEPROM, these

changes are not retained through power cycles. The

power-on value is the last value written with SEEB dis-

abled. This function can be used to limit the number of

EEPROM writes during calibration or to change the

monitor thresholds periodically during normal operation

helping to reduce the number of times EEPROM is writ-

ten. Figure 19 indicates which locations are shadowed

EEPROM.

EEPROM

(256 BYTES)

FFh

I2C ADDRESS A0h

00h

ALARM-

ENABLE ROW

(8 BYTES)

PASSWORD ENTRY

(PWE) (4 BYTES)

TABLE-SELECT

BYTE

FFh

80h

F8h

TABLE 01h

EEPROM

(120 BYTES)

F7h

7Fh

00h

LOWER

MEMORY

3W CONFIG

FFh

80h

F8h

TABLE 02h

NONLOOKUP

TABLE CONTROL

AND

CONFIGURATION

REGISTERS

E7h

80h

TABLE 04h

MOD

LOOKUP TABLE

(72 BYTES)

C7h

F8h

TABLE 05h

ALARM-ENABLE ROW

(8 BYTES) FFh

80h TABLE 06h

TRACKING ERROR

LOOKUP TABLE

(36 BYTES) A3h

80h

TABLE 07h

DAC1 LUT

A3h

80h

TABLE 08h

DAC2 LUT

A3h

NOTE 1: IF ASEL = 0, THEN THE MAIN DEVICE I2C SLAVE ADDRESS IS A2h.

IF ASEL = 1, THEN THE MAIN DEVICE I2C SLAVE ADDRESS IS DETERMINED BY THE VALUE IN

TABLE 02h, REGISTER 8Ch.

NOTE 2: TABLE 00h DOES NOT EXIST.

NOTE 3: ALARM-ENABLE ROW CAN BE CONFIGURED TO EXIST AT TABLE 01h OR TABLE 05h USING THE

MASK BIT IN TABLE 02h, REGISTER 89h.

Figure 19. Memory Map

DS1874 Datasheet(PDF) 29 Page - Maxim Integrated Products

DS1874 Datasheet(HTML) 29 Page - Maxim Integrated Products

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88

Datasheet Download

Link URL